
^{12}C (1980AJ01)(See Energy Level Diagrams for ^{12}C) GENERAL: See also (1975AJ02) and Table 12.7 [Table of Energy Levels] (in PDF or PS). Shell model: (1974BO1P, 1975BI05, 1975BO27, 1975FR06, 1975GI1C, 1975MU13, 1975WA30, 1976BA24, 1977CA02, 1977CA08, 1977GR02, 1977JA14, 1978FU13, 1978MU04, 1978SV01, 1979LO1F). Collective and deformed models: (1974BO1P, 1975BO27, 1975KI21, 1975LE14, 1975MC15, 1975SO07, 1976GL1C, 1976PA25, 1977CA08, 1977TH03, 1977UE01, 1977VI03, 1979MA1J). Cluster and alpha particle models: (1974AG06, 1975AB1E, 1975BA16, 1975HO1E, 1975IN04, 1975KA29, 1975KR1D, 1975KU1N, 1975NE1B, 1975RO1B, 1975WA30, 1976CA05, 1976FL1B, 1976FU1G, 1976HA09, 1976HO1F, 1976HO1A, 1976KA14, 1976KI16, 1976SA1F, 1976VA21, 1977AG03, 1977BA76, 1977BE49, 1977FU1E, 1977HO1E, 1977HO1F, 1977KA1U, 1977KA1Q, 1977KH02, 1977MY1A, 1977MY1B, 1977NA13, 1977SA19, 1977SA1C, 1977TA1J, 1977TA1K, 1977UE01, 1977UE1B, 1978AR1H, 1978DZ01, 1978HO1E, 1978HU09, 1978IS04, 1978MA1U, 1978OG1A, 1978OS01, 1978UE1B, 1979GO1P, 1979HE1G, 1979KA1P). Special levels: (1974BO1P, 1975BA16, 1975HO1E, 1975IM02, 1975MC16, 1975NA21, 1975NG1A, 1976BA24, 1976FU1G, 1976GA16, 1976GL09, 1976GO1J, 1976HA09, 1976HO1A, 1976IR1B, 1976KI01, 1976VA21, 1977BA76, 1977CA08, 1977GR02, 1977GR24, 1977JA14, 1977KA1Q, 1977KN03, 1977MO1Q, 1977SA17, 1977TA1J, 1977UE01, 1977UE1B, 1978AR1H, 1978BA31, 1978BE56, 1978GO1K, 1978HO1E, 1978HU09, 1978LA1D, 1978MC04, 1978MI04, 1978RO17, 1978SH04, 1979DU1E, 1979HA1E, 1979PO03). Electromagnetic transitions: (1974BO1P, 1974HA1C, 1975BE24, 1975BI05, 1975BO27, 1975DO1D, 1975KA29, 1975MC16, 1976KI01, 1976VO1C, 1977AG03, 1977BE49, 1977DE15, 1977DO06, 1977FU1E, 1977GR02, 1977GR24, 1977KA1Q, 1977MA1Y, 1977MY1B, 1977YO1D, 1978AR1H, 1978FU13, 1978GO1K, 1978KI08, 1978MU04, 1978MY1B, 1978UE1B, 1979MO07, 1979MO1U, 1979MO1X, 1979PO03). Giant resonances: (1974HA1C, 1975CO1E, 1975DO10, 1975GE1K, 1975GO22, 1975MC15, 1976BE1P, 1976KO1G, 1976MS01, 1977DE15, 1977GO1F, 1977KN03, 1977MA2E, 1977SA1Q, 1979DE1T, 1979GO1Q). Special reactions: (1975AB1D, 1975AL04, 1975AR14, 1975FA1D, 1975GR13, 1975HU14, 1975KO1F, 1975ME1F, 1975PE03, 1975RE08, 1976AB04, 1976BA08, 1976BE1K, 1976BO1N, 1976BU16, 1976CH28, 1976DA1G, 1976EG02, 1976FR05, 1976HE1H, 1976HI05, 1976HI01, 1976HO1D, 1976LE12, 1976LE1F, 1977AR06, 1977BU07, 1977CE1B, 1977FE1B, 1977GE08, 1977GO07, 1977HA18, 1977HO27, 1977JA1J, 1977KA1P, 1977KO1Y, 1977KU1D, 1977LI1J, 1977MA1U, 1977MA1W, 1977NA03, 1977PR05, 1977RE08, 1977SH1D, 1977ST1J, 1977ST1G, 1977TO1G, 1977UD1A, 1977VA02, 1977YA1B, 1978AB08, 1978BA24, 1978BH03, 1978BI03, 1978BI08, 1978DI04, 1978FU1H, 1978GE1F, 1978GE1C, 1978GO1N, 1978GR1F, 1978HE1J, 1978HE1C, 1978KO01, 1978LE15, 1978OB01, 1978TU06, 1978VO1D, 1978VO1A, 1978WE1D, 1978WI1G, 1979AL1H, 1979CH06, 1979DU1E, 1979DY01, 1979GA04, 1979GO11, 1979HA1E, 1979PO10, 1979SC08, 1979SI1A, 1979SI09, 1979WA1H, 1979WE06). Applied topics: (1975BE1U, 1975GA1E, 1976EC1B, 1976LE1Q, 1976SC1G, 1977BE2F, 1977FI1A, 1977MO1B, AN78E, 1978HE1K, 1978KE1E, 1978LE1P, 1978NA21, 1978TR1E, 1979AN1L, 1979EN1D, 1979GR1E, 1981JA1H). Muon and neutrino capture and reactions: (1974EN10, 1974KO1H, 1974WA1C, 1975BA40, 1975BA56, 1975CH22, 1975DO1F, 1975DO10, 1975DO1D, 1975FE1B, 1975GE1E, 1975IM02, 1975KI2A, 1976DA1H, 1976DO1J, 1976HO1G, 1976SU03, 1977BA1P, 1977BO2C, 1977BR1K, 1977CA1M, 1977DO06, 1977HW01, 1977LE1K, 1977MU1A, 1977PO1B, 1977PR1B, 1977WA1F, 1977WA1G, 1978BA1G, 1978BA57, 1978BR1C, 1978DE15, 1978GU05, 1978HW1A, 1978KO31, 1978MU04, 1978PA06, 1978PA1F, 1978SE1B, 1978WU01, 1979BE1N, 1979DE01, 1979DO1C, 1979FI1E, 1979PA1J, 1979PR1D, 1979RO03, 1979RO1H, 1979TR05, 1979VE1D). Pion capture and pion reactions (See also reactions 39 and46.): (1973BA1M, 1974AR1E, 1974AZ1B, 1974AZ1C, 1974BO1D, 1974BO1Y, 1974CA1K, 1974GR1K, 1974LU1D, 1974SP1A, 1974ST1K, 1975AB12, 1975AL1E, 1975AM03, 1975AN1L, 1975AZ1C, 1975AZ1D, 1975BA14, 1975BA1L, 1975BA54, 1975BA1G, 1975BA66, 1975BA1P, 1975BA57, 1975BA1W, 1975BH03, 1975BO1B, 1975BR1H, 1975BR1D, 1975BR1K, 1975BU1E, 1975BU1A, 1975BU1G, 1975CA17, 1975CA31, 1975CE03, 1975CO06, 1975CO1G, 1975DR02, 1975DU06, 1975DU1A, 1975EI1A, 1975EI1B, 1975ER08, 1975FU07, 1975GA08, 1975GI09, 1975GI13, 1975HE06, 1975HU1D, 1975HU13, 1975IN1B, 1975JU02, 1975KA03, 1975KA1G, 1975KI1E, 1975KO1F, 1975KO25, 1975KU02, 1975LO1F, 1975MA1M, 1975NA08, 1975NA16, 1975NI1B, 1975PA1D, 1975PE1C, 1975RA1N, 1975RO11, 1975RO1G, 1975SC1V, 1975SC1N, 1975SH1D, 1975SH17, 1975SI10, 1975SI18, 1975SI1E, 1975ST1G, 1975TA1C, 1975TO10, 1975VA1D, 1975VE05, 1975VO1D, 1975WA1H, 1975WA1J, 1976AL1J, 1976AL1K, 1976AS1B, 1976AZ1A, 1976BA1V, 1976BA1X, 1976BA47, 1976BA1R, 1976BA2A, 1976BE39, 1976BE1K, 1976BO1P, 1976BO1K, 1976BR1M, 1976BR1N, 1976BU1F, 1976BU1D, 1976CA01, 1976CA23, 1976CA1H, 1976CH1G, 1976CH1H, 1976CO10, 1976CO13, 1976DO1D, 1976DO06, 1976DR1D, 1976DU1B, 1976DU1F, 1976ED1A, 1976EI1B, 1976EN02, 1976FR14, 1976FU1E, 1976GI1E, 1976GU17, 1976IV03, 1976KA02, 1976KI1E, 1976KI1H, 1976KI07, 1976LE02, 1976LE1P, 1976LI24, 1976LI26, 1976LO1C, 1976MA1U, 1976MA48, 1976MI14, 1976NA16, 1976NI02, 1976OS03, 1976PI1B, 1976PI12, 1976RO14, 1976SR1A, 1976TA1E, 1976TH09, 1976TR1A, 1976VA1F, 1976WA10, 1976WA07, 1977AB09, 1977AH04, 1977AL15, 1977AL1C, 1977AL1V, 1977AN1H, 1977AN1J, 1977AN1K, 1977AP1A, 1977AP1B, 1977AR1F, 1977AR1J, 1977AU1G, 1977AU1H, 1977BA60, 1977BA2H, 1977BA51, 1977BA1Q, 1977BA2G, 1977BA2Q, 1977BA2R, 1977BA73, 1977BA2V, 1977BE1W, 1977BE2K, 1977BE69, 1977BE35, 1977BO05, 1977BO1X, 1977BO1E, 1977BO1Y, 1976BR1L, 1977BU25, 1977BU1K, 1977BU1L, 1977CH1N, 1977CO1N, 1977DI03, 1977DI1B, 1977DO06, 1977DR1E, 1977DY02, 1977EI1A, 1977ER1A, 1977ER1B, 1977FR09, 1977FU11, 1977FY1A, 1977GE04, 1977GE1D, 1977GI06, 1977GI14, 1977GR1G, 1977HA1U, 1977HA1V, 1977HI1E, 1977HO1B, 1977JA1G, 1977KA1N, 1977KI1L, 1977KO25, 1977KU1G, 1977LE1H, 1977LE1G, 1977LI11, 1977MA1R, 1977MA1M, 1977MA2C, 1977MA35, 1977MC1E, 1977MO12, 1977NA02, 1977NA1K, 1977NA1L, 1977NA1M, 1977OH1B, 1977PI1D, 1977PI02, 1977PI1E, 1977PI09, 1977PR1G, 1977RA1A, 1977RO21, 1977RO25, 1977SC1F, 1977SE13, 1977SH14, 1977SI01, 1977SM06, 1977SP1B, 1977ST09, 1977ST1G, 1977TH1F, 1977VI1A, 1977WA1H, 1977WE1J, 1977WI1E, 1978AL1N, 1978AM01, 1978AN1E, 1978AN2B, 1978AN1F, 1978AN1G, 1978AN1H, 1978AR08, 1978AR18, 1978AZ1C, 1978AZ1D, 1978AZ02, 1978BA50, 1978BA1Y, 1978BA1T, 1978BE1N, 1978BE64, 1978BE1X, 1978BE27, 1978BH01, 1978BL1B, 1978BO01, 1978BO1P, 1978BO25, 1978BO26, 1978BR1J, 1978BR1K, 1978BU1J, 1978BU1L, 1978CH1V, 1978CO02, 1978CO16, 1978DO07, 1978DY01, 1978EI1A, 1978EP01, 1978EP02, 1978ER1C, 1978FU04, 1978FU09, 1978GA1D, 1978GA11, 1978GI01, 1978GI05, 1978GI14, 1978HA34, 1978HA1V, 1978HA37, 1978HI03, 1978JA09, 1978JA1G, 1978JO03, 1978JO09, 1978KI08, 1978KL06, 1978KO34, 1978KW1A, 1978LA1L, 1978LA08, 1978LI1E, 1978MA1T, 1978MA1J, 1978ME05, 1978ME1F, 1978MI02, 1978MO01, 1978MO25, 1978MO23, 1978NA1N, 1978PA14, 1978PE1D, 1978PE11, 1978PE12, 1978RO1J, 1978RO16, 1978RO1H, 1978SC1G, 1978SC1H, 1978SE07, 1978SI1E, 1978SI1D, 1978SP06, 1978TA1L, 1978TH1C, 1978TH1D, 1978VL1B, 1978WA1B, 1978WE1H, 1978WO11, 1978YO1D, 1978YO02, 1979AL1T, 1979AL1U, 1979AM1D, 1979AN1J, 1979AN1K, 1979AR1H, 1979AR1K, 1979BA04, 1979BA16, 1979BA2G, 1979BA1M, 1979BA2H, 1979BE1N, 1979BL1H, 1979BO1W, 1979BO1B, 1979BO1Y, 1979BO1U, 1979BO12, 1979BO2C, 1979BO2D, 1979BO2E, 1979BR1F, 1979BU1K, 1979BU1D, 1979CE1A, 1979CH1P, 1979CH06, 1979CH05, 1979CH1U, 1979CH1V, 1979CH1W, 1979CO1L, 1979CO1M, 1979CO1H, 1979CO1N, 1979CR1E, 1979DA1J, 1979DA1L, 1979DE06, 1979DE1U, 1979DI1A, 1979DY02, 1979EI1A, 1979EL1E, 1979EN1E, 1979GA08, 1979GU01, 1979GY1A, 1979GY1B, 1979HA07, 1979HO1F, 1979HU02, 1979JA1K, 1979KL1D, 1979KL1E, 1979KL1F, 1979KL1G, 1979KN1E, 1979KU1J, 1979LA02, 1979LA1M, 1979LU1C, 1979MA07, 1979MA1P, 1979MA2H, 1979MA2J, 1979MI1F, 1979MI1G, 1979MI06, 1979MO1V, 1979MO1W, 1979NA1M, 1979NA1N, 1979NA1P, 1979NA1E, 1979OH1A, 1979OH1C, 1979PE1G, 1979PI1G, 1979PR1D, 1979RE1A, 1979SA1P, 1979SC02, 1979SC1J, 1979SH1M, 1979SH1N, 1979SH1P, 1979SH1Q, 1979SI1F, 1979SO1D, 1979ST02, 1979ST1K, 1979ST1N, 1979TA1J, 1979WA1J, 1979WI1A, 1979WI1J, 1979WU07, 1979ZI1C). Reactions involving antiprotons: (1977RO23, 1977WE1E, 1978YO02). Kaon capture and reactions involving kaons and other mesons: (1974BO1Y, 1975DU1A, 1975PN1A, 1975PO1C, 1975TA1C, 1975VA1C, 1976AR1K, 1976BO1P, 1976BO1K, 1976BR1G, 1976DE1D, 1976EI1A, 1976KI1E, 1976KI1G, 1977BO2C, 1977CO04, 1977DO11, 1977JU1C, 1977PO1A, 1977TH1D, 1978AL04, 1978AT01, 1978BA1W, 1978BO1P, 1978BR1G, 1978DA1A, 1978EP02, 1978HE02, 1978KW1A, 1978PO1A, 1978SC1G, 1978TH1E, 1979BE2G, 1979BE2H, 1979BO12, 1979DA1K, 1979DO05, 1979GA1D, 1979KI1C, 1979MA2F, 1979MA2G, 1979PO1D, 1979WA1J). Other topics: (1974BO1Y, 1974ZU1A, 1975BE48, 1975BL1E, 1975CA1N, 1975FA03, 1975FR06, 1975GA1G, 1975HO1E, 1975KO1C, 1975LE1E, 1975MU13, 1975PN1A, 1975PO1C, 1975SC1M, 1975SO04, 1975SO07, 1976BR1G, 1976DA1E, 1976ES1A, 1976GL09, 1976HA09, 1976IR1B, 1976KH04, 1976KI01, 1976KI16, 1976LO1D, 1976MA04, 1976SA16, 1976ST13, 1976VA1C, 1977BO2C, 1977CA02, 1977DE16, 1977JE04, 1977KI1K, 1977MO1Q, 1977NA13, 1977PO1A, 1977SA17, 1978BA31, 1978BI14, 1978DA1A, 1978HA1U, 1978KW1A, 1978LA1D, 1978LI1D, 1978MC04, 1978ON01, 1978OS01, 1978OS1B, 1978PO1A, 1978RO17, 1978SH04, 1978UL02, 1979CH06, 1979DA1K, 1979GA1D, 1979HE1F, 1979HE1G, 1979KI1C, 1979MA2F, 1979OS02, 1979QU1A). Ground state of ^{12}C: (1974DE1E, 1974EN10, 1975BE31, 1975CA1N, 1975FR05, 1975FR06, 1975KA29, 1975KU1N, 1975LE05, 1975LE1E, 1975MA50, 1975MU13, 1976BE1G, 1976FU06, 1976GA16, 1976GI11, 1976KI16, 1976SR1A, 1977AN21, 1977BE49, 1977FI12, 1977GR08, 1977JE04, 1977MA35, 1977MA1Y, 1977MY1A, 1977NO07, 1977PA25, 1977SA17, 1977TH03, 1978AN07, 1978BE56, 1978BI14, 1978GO1K, 1978HE1D, 1978MU04, 1978NA07, 1978NE03, 1978ON01, 1978RO17, 1978SM02, 1978SV01, 1978TA09, 1978UE1B, 1978UL02, 1978ZA1D, 1979GO1P, 1979PO03, 1979TA1K).
See also (1979BE1N) and reaction 44.
For E(^{6}Li) = 1.2 to 2.8 MeV, population ratios of ^{7}Be*(0.43), ^{7}Li*(0.48) and ^{10}B*(0.72) (reactions (e), (f) and (c)) remain approximately constant. Simple tunneling or compound nucleus models are not compatible with the data and a direct interaction through longrange tails is suggested (1962MC12). Absolute reaction cross sections at E(^{6}Li) = 2.1 MeV are in reasonable agreement with estimates based on barrier penetration. A strong preference for αemission suggests that the favored mechanism involves interacting clusters (1963HU02). The α_{0} yield shows a broad peak at E(^{6}Li) ≈ 10 MeV (1970FR06: E(^{6}Li) = 4 to 24 MeV). The yield of ^{6}Li + ^{6}Li → 3α (reaction (g)) for E(^{6}Li) = 4 to 20 MeV is dominated by a broad resonance (Γ = 5 MeV) at the Coulomb barrier which is consistent with the formation of a quasimolecular state ^{6}Li + ^{6}Li with τ ≈ 10^{21} sec (1970FR06). A multiparameter coincidence study of reaction (g) for E(^{6}Li) = 2 to 13 MeV shows the importance of direct interactions: the data were fitted assuming an (α + d) cluster structure for ^{6}Li and an interaction potential acting only between the two deuterons (1971GA21, 1972GA32). The cross section for reaction (g) rises rapidly for E(^{6}Li) = 1.0 to 5.5 MeV. Thermonuclear reaction rates have been calculated for kT values of 10 to 1000 keV (1978NO1E). Cross sections for reaction (e) are reported at E(^{6}Li) = 1.6, 3.5 and 5.0 MeV (1977RU06). See also (1975NO1C, 1976FI1F), ^{7}Li, ^{7}Be, ^{8}Be and ^{10}B in (1979AJ01), ^{11}B and ^{11}C here and (1975AJ02).
The elastic scattering (reaction (b)) follows the Mott formula at low energies [≲ 4.0 MeV] (1966PI02: E(^{6}Li) = 3.2 to 7.0 MeV). A broad structure is observed in the excitation functions [θ_{c.m.} = 60° and 90°] at E(^{6}Li) ≈ 13 MeV (1973GR34) and ≈ 26 MeV [Γ ≈ 7 MeV] (1971FO08: θ_{c.m.} = 90°; E(^{6}Li) to 34 MeV). The elastic scattering appears to be dominated by absorption (1971FO08). Excitation functions for the transitions to ^{6}Li*_{3.56} + ^{6}Li*_{3.56} have been measured for E(^{6}Li) = 28.0 to 33.0 MeV (1970NA02: θ_{c.m.} = 90°) and 28.0 to 36.0 MeV (1973WH02, 1974WH01, 1974WH02; θ_{c.m.} = 88°) [also ratio of ^{6}Li*_{3.56} + ^{6}Li*_{3.56} to formation of ^{6}He_{g.s.} + ^{6}Be_{g.s.} at E(^{6}Li) = 28, 32, 34 and 36 MeV]. The latter results have been compared with calculations using microscopic DWBA analysis. See also ^{6}He and ^{6}Li in (1979AJ01).
See (1975AJ02).
Excitation functions and angular distribution studies have been carried out by (1972BL17: E(^{3}He) = 1.0 to 6.0 MeV; γ_{0}, γ_{1}, γ_{2}), (1972LI29: 1.5 to 11 MeV; γ_{0}, γ_{1}, γ_{2}, γ_{3}), (1964BL12: 2 to 4.5 MeV; γ_{0}, γ_{1}) and (1974SH01: 3 to 21 MeV (γ_{2}), to 24 MeV (γ_{0}), to 26 MeV (γ_{1}, γ_{3})). Observed resonances are shown in Table 12.9 (in PDF or PS). ^{12}C*(28.2) appears to be formed by s and dwave capture. The γ_{0} and γ_{2} transitions to the 0^{+} states ^{12}C*(0, 7.7) are strong and show a similar energy dependence. A strong nonresonant contribution is necessary to account for the γ_{1} yield (1972BL17). The resonance structure reported by (1974SH01) appears to confirm the role of 3p3h configurations for ^{12}C excitations somewhat above the giant resonance region. The γ_{3} yield is relatively unstructured (1972LI29, 1974SH01: to E(^{3}He) = 26 MeV). See also (1975AJ02).
Excitation functions for neutrons [and production cross sections for ^{11}C] have been measured for E(^{3}He) = 1.2 to 10 MeV for several neutron groups: see (1968AJ02, 1975AJ02) for a listing of the earlier references. No sharp structure is observed but there is some suggestion from angular distribution data and excitation functions at forward angles for a broad structure (Γ ≈ 350 keV) at E(^{3}He) ≈ 2 MeV: E_{x} = 27.8 MeV (1963DU12, 1965DI06). The total cross section for ^{11}C production shows a broad maximum, σ = 113 mb at E(^{3}He) = 4.3 MeV (1966HA21). Polarization measurements have been carried out for E(^{3}He) = 2.1 to 3.9 MeV (1971TH15: n_{0}, n_{1}, n_{2+3}: the shapes of the measured angular distributions for n_{0} and n_{1} show very gradual changes with energy. It is suggested that a significant direct interaction contribution is present (1971TH15). Excitation functions and angular distributions for protons (reaction (b)) have been measured for E(^{3}He) = 1.0 to 10.2 MeV for a number of proton groups: see (1968AJ02, 1975AJ02) for a listing of the earlier references and (1977LI1F: 3 to 6 MeV). No pronounced structures are reported. Polarization measurements have been carried out at E(^{3}He) = 14 MeV (1977IR01; P_{0}, p_{1}). For reaction (c) see (1974MO23; to E(^{3}He) = 31 MeV). See also (1974LO1B) and ^{11}B, ^{11}C.
Analyzing powers have been measured at E(pol. ^{3}He) = 33.3 MeV for nine proton groups (1976KA23). The cross section for ground state tritons (reaction (b)) increases monotonically for E(^{3}He) = 2.5 to 4.2 MeV (1969OR01: θ = 40°) and then shows a broad maximum at E(^{3}He) ≈ 4.5 MeV (1967EA01: θ = 20°). See also (1976UE01) for continuum measurements. See also (1974LO1B) and ^{9}B, ^{10}B in (1979AJ01).
The elastic scattering excitation function decreases monotonically for E(^{3}He) = 4.0 to 9.0 MeV (1967EA01: θ = 45°) and 15.0 to 21.0 MeV (1972MC01: θ_{c.m.} = 90°). At θ_{c.m.} = 111° a slight rise is observed for E(^{3}He) = 19 to 21 MeV (1972MC01). Polarization measurements have been reported at E(^{3}He) = 18 (1972MC01), 31.4 (1971EN03) and 32.8 MeV (1975BU11; polarized ^{3}He). See also (1976RO1L) and ^{9}Be in (1979AJ01).
Excitation functions for the α_{0} group for E(^{3}He) = 2 to 10 MeV show evidence of a complex structure at ≈ 4 MeV [E_{x} ≈ 29.3 MeV] (1978BI15: see also for σ_{t} and α_{0} in the range 2 → 10 MeV). Analyzing powers have been measured at E(pol. ^{3}He) = 33.3 MeV for the groups to ^{8}Be*(16.9, 17.6, 19.2) (1976KA23). See also (1974SA1K: 1.3 → 3.2 MeV) and (1976RO1L). Reaction (b) has been studied for E(^{3}He) = 2.9 to 10 MeV (1975RO09, 1977GO16). See also (1979BA27), (1975AJ02) and ^{8}Be in (1979AJ01).
Excitation functions measured for E(^{3}He) = 4 to 10 MeV show some fluctuations: see (1975AJ02). See also ^{6}Li in (1979AJ01).
Neutron groups have been observed to ^{12}C*(0, 4.4, 7.7, 9.6, (10.1), (10.8)). Angular distributions of neutron groups have been measured at many energies in the range E_{α} = 1.75 to 23 MeV: see (1968AJ02, 1975AJ02) for references. The mean life of ^{12}C*(4.4) [J^{π} = 2^{+}] is 57^{+23}_{17} fsec, Γ_{γ} = 11.5^{+5}_{3.2} meV (1966WA10). ^{12}C*(7.7) decays predominantly into ^{8}Be + α: J^{π} = 0^{+}. See also Table 12.8 (in PDF or PS), (1978LO1C), (1974LO1B), (1978MC1F; applied work) and ^{13}C in (1981AJ01).
At E(^{9}Be) = 26 MeV, θ_{lab} = 10°, the population of ^{12}C*(0, 4.4, 7.7, 9.6, 10.8, 11.8) is reported: the strongest transition is to ^{12}C*(9.6) (1975VE10). See also (1975AJ02).
At E(^{9}Be) = 26 MeV, θ = 10°, strong transitions are observed to ^{12}C*(4.4, 7.7, 9.6) (1975VE10).
At E(^{3}He) = 13 MeV neutron groups are observed to ^{12}C*(0, 4.4, 7.7, 16.1, 17.8) and to excited states at E_{x} = 23.53 ± 0.04 [Γ < 0.4 MeV] and 27.611 ± 0.020 MeV. The latter is formed with a 0° cross section of ≈ 200 μb/sr and is taken to be the first 0^{+}, T = 2 state of ^{12}C (1974GO23).
The (d, γγ) excitation function [via the J^{π} = 1^{+}, T = 1 state at E_{x} = 15.1 MeV] has been measured for E_{d} = 2.655 to 2.91 MeV. The nonresonant yield of 15 MeV γrays is due to direct capture process or to a very broad resonance: no sharp resonances are observed corresponding to the T = 2 state reported in reaction 4 [Γ_{d0}Γ_{γ}/Γ ≲ 0.2 eV] (1970BL09, 1974HA1G). See also (1975AJ02).
The thintarget excitation function in the forward direction in the range E_{d} = 0.3 to 4.6 MeV shows some indication of a broad resonance near E_{d} = 0.9 MeV. Above E_{d} = 2.4 MeV, the cross section increases rapidly to 210 mb/sr at 3.8 MeV, and then remains constant to 4.6 MeV (1954BU06, 1955MA76). Excitation functions have also been measured for E_{d} = 3.2 to 9.0 MeV: see (1975AJ02). The branching ratios at 90° for the transitions to the ground states of ^{11}C and ^{11}B[n_{0}/p_{0}] have been measured for E_{d} = 1.0 to 2.0 MeV by (1973BR24). Polarization measurements have been carried out for E_{d} = 1.20 to 4.0 MeV: see (1975AJ02). See also (1969WO09), (1974LO1B), (1977YO1F; applied) and ^{11}C.
Yields of protons have been measured for E_{d} = 0.14 to 12 MeV: see (1968AJ02, 1975AJ02). No clear resonance structure is observed. There is some indication that a broad resonance, corresponding to ^{12}C*(27.1) affects the p_{1} and p_{3} yields (1964BR1A). Upper limits for the partial widths (p_{0} → p_{3}) of the T = 2 state reported in reaction 4 are given by (1970BL09). Polarization studies have been carried out for E_{d} = 1.15 to 21 MeV: see (1968AJ02, 1975AJ02). See also ^{11}B.
The yield of elastically scattered deuterons has been measured for E_{d} = 1.0 to 2.0 MeV: resonances at E_{d} = 1.0 and 1.9 MeV are suggested by (1969LO01). Excitation functions for the deuterons to ^{10}B*(1.74, 2.16) [J^{π}; T = 0^{+}; 1 and 1^{+}; 0, respectively] have been measured at several angles for E_{d} = 4.2 to 16 MeV: they are characterized by rather broad, slowly varying structures. The ratio σ_{1.74}/σ_{2.15} varies from 0.69 ± 0.04% at E_{d} = 6.5 MeV to 0.16 ± 0.04% at E_{d} = 12.0 MeV corresponding, respectively, to isospin impurities of ≈ 2% and ≈ 0.5% (1974ST01). No resonance structure is observed in the elastic yield for E_{d} = 14.0 to 15.5 MeV (1974BU06). Polarization measurements are reported at E_{d} = 12.5 MeV (1975ZA08) and at 15 MeV (1974BU06). See also (1977IZ01; theor.) and ^{10}B in (1979AJ01).
For polarization measurements at E_{d} = 15 MeV involving ^{9}Be*(0, 2.43) and ^{9}B*(0, 2.36) see (1974LU06). See also ^{9}Be and ^{9}B in (1979AJ01).
Excitation functions have been measured for the α_{0} and α_{1} groups for E_{d} = 0.4 to 12 MeV [see (1968AJ02, 1975AJ02)] and for E_{d} = 2.5 to 4.5 MeV (1975VA04; α_{0}) and 0.8 to 9.0 MeV (1978BU04: α_{0}). Maxima in the α_{0} yields are reported at E_{d} = 1, 2, 4.5 and (6) MeV. The first is attributed to an swave resonance corresponding to a state with E_{x} ≈ 26.0 MeV, Γ ≈ 0.5 MeV (1968FR07). The resonance structures at ≈ 2.0 and 4.5 MeV (Γ ≳ 1 MeV) may both involve the isoscalar giant resonance: E_{x} ≈ 28 MeV, Γ ≈ 4 MeV (1978BU04). No evidence for the T = 2 state was found in the α_{0} and α_{1} yield curves taken in 2 keV steps for 27.35 < E_{x} < 27.65 MeV (1970BL09). For yields of the α particles to ^{8}Be*(17.6, 18.1) see (1970CA12) [also discussed in ^{8}Be (1959AJ76)]. Reaction (b) has been studied for E_{d} = 2.7 to 5.0 MeV: see (1975RO09, 1975VA04, 1977GO16) and at E_{d} = 0.36 MeV (1977NO10). The latter work suggests that a 3^{} and a 4^{+} state in ^{12}C contribute dominantly to the sequential decay. See also (1976GR1F) and (1979SE04; theor.).
See (1975AJ02) and ^{6}Li in (1979AJ01).
Proton groups observed by (1958MO99, 1959AL1A, 1962BR10) are displayed in Table 12.10 (in PDF or PS). Angular distributions of many of these groups have been measured for E(^{3}He) = 1.4 to 14 MeV: see (1968AJ02). From studies of ^{10}B(^{3}He, pα)^{8}Be it is determined that ^{12}C*(7.7, 9.6, 10.8, 14.1, 16.1) have natural parity π = (1)^{J}, and that ^{12}C*(11.8, 12.7, 13.4), which decay only to ^{8}Be*(2.9) and not to the ground state, have unnatural parity: see Tables 12.8 (in PDF or PS) and 12.10 (in PDF or PS) and (1968AJ02). ^{12}C*(12.7) decays also by γemission. The charge dependent matrix element connecting ^{12}C*(12.7, 15.1) is 110 ± 30 keV (1976AD03, 1977AD02): see also reactions 22, 44, 50, 73, 74 and 86. ^{12}C*(16.11, 16.58) show decay to both ^{8}Be*(0, 2.9). The consequent assignment of natural parity is consistent with J^{π} = 2^{+} for the former but not with J^{π} = 2^{} for the latter. For ^{12}C*(16.11) observed values of Γ_{α0}/Γ are 0.05  0.12; the decay to 3α occurs rarely if at all (1966WA16). Table 12.8 (in PDF or PS) summarizes the decay parameters of some of the excited states of ^{12}C. Reactions (c) and (d) have been studied by (1970BO39). The latter, at E(^{3}He) = 11 MeV, appears to proceed via a state in ^{12}C at E_{x} = 20.5 ± 0.1 MeV, which is suggested to be J^{π} = 3^{+}, T = 1. The relative intensities of the decays of ^{12}C states with 20 < E_{x} < 25 MeV via channels (c) and (d) is estimated. The α_{0} decay is very small, consistent with the expected population of T = 1 states (1970BO39). See also (1975NA1C), (1975MA21), (1976EP1A; astrophys.), ^{8}Be in (1979AJ01) and ^{13}N in (1981AJ01).
Angular distributions of d_{0} and d_{1} have been measured at E_{α} = 15.1 to 25.2 MeV (1975VA19). The relative populations of ^{12}C*(12.71, 15.11) [both 1^{+}; the latter isospin forbidden] leads to values of ≲ 260 keV (1975SP04), 285 ± 30 keV (1977LI02) for the charge dependent matrix element between these two states: see also reactions 21, 44, 50, 73, 74 and 86. See also (1976GU1B, 1976LE1K). (1978ZE03; theor.) and (1975AJ02).
At E(^{6}Li) = 4.9 MeV angular distributions have been obtained for the αparticles to ^{12}C*(0, 4.4, 7.7, 9.6). The population of ^{12}C*(11.8, 12.7) is also reported (1966MC05), as is that of ^{12}C*(15.11) [T = 1] (1964CA18: E(^{6}Li) = 3.8 MeV): the intensity ratio α_{15.1}/α_{12.7} = 3 ± 2%.
See (1975SE03, 1975SE04) and ^{11}B.
Angular distributions involving ^{12}C*_{4.4} + ^{12}C_{g.s.} and ^{12}C*_{4.4} + ^{12}C*_{4.4} have been measured at E(^{14}N) = 22.5 and 30 MeV (1969IS01) and 73.9 and 93.6 MeV (1977MO1A). See also (1973ST1A).
Angular distributions involving ^{14}N_{g.s.} + ^{12}C_{g.s.} and ^{14}N_{g.s.} + ^{12}C*_{4.4} have been measured at E(^{16}O) = 30 and 32.5 MeV and also at 26 MeV for the double ground state transition (1969IS01).
In view of the complexity of the available information on these three reactions, we will first summarize the recent experimental results and then review the evidence for the parameters of ^{12}C states observed as resonances. (a) In the range 4 MeV < E_{p} < 14.5 MeV σ(γ_{0}) is dominated by the giant dipole resonance at E_{p} = 7.2 MeV (E_{x} = 22.6 MeV, Γ_{c.m.} = 3.2 MeV), while the giant resonance in γ_{1} occurs at E_{p} ≈ 10.3 MeV (E_{x} = 25.4 MeV, Γ_{c.m.} ≈ 6.5 MeV): see (1964AL20). A study of the giant dipole resonance region with polarized protons (E_{p} = 6 to 14 MeV) sets new limits on the configuration mixing in the γ_{0} giant resonance (1972GL01). The E2 strength is found to be centered near E_{p} = 12 MeV: it exhausts ≳ 30% of the isoscalar E2 sum rule (1976MAZG, 1976MAZL). The analysis of γ_{1} is more complicated: the asymmetry results are consistent either with a single J^{π} = 2^{} state or with interference of pairs of states such as (1^{}, 3^{}), (2^{}, 3^{}) and (1^{}, 2^{}) (1972GL01). See also (1979AR1G). Measurements of differential cross sections at 90° (E_{p} = 13 to 22 MeV), of angular distributions (E_{p} = 7 and 14 to 21 MeV), and of total cross sections (E_{p} = 14 to 21 MeV) have been reported by (1972BR26). The 90° yield of γ_{0}, γ_{1}, γ_{2} and γ_{3} [to ^{12}C*(0, 4.4, 7.7, 9.6)] has been studied by (1977SN01): the γ_{2} yield shows a peak at E_{p} ≈ 14.3 MeV with a cross section ≈ 2.3% that of γ_{0} [in γ_{0} yield, E_{res} = 15.0 MeV (1977SN01), 14.8 MeV (1969KE02)] and perhaps as well a low intensity structure at E_{p} = 11.8 MeV. The γ_{3} yield exhibits two asymmetric peaks at E_{p} = 12.5 and 13.8 MeV (Γ ≈ 0.7 and 2.5 MeV) and a weaker structure at ≈ 9.8 MeV (1977SN01). The (pγγ) process [via ^{12}C*(15.1)] has been studied in the vicinity of the first two T = 2 states; only a nonresonant yield is observed: (2J + 1)Γ_{γ}Γ_{p}/Γ < 0.25 eV and < 1.5 eV, respectively for ^{12}C*(27.4, 28.6) (1977NA1F). At E_{p} = 40, 60 and 80 MeV, radiative capture is observed to a state, or a narrow group of states, at E_{x} = 19.2 ± 0.6 MeV (1979KO05). Work on other resonances is reported below. (b) Excitation functions have been measured for E_{p} = 3.0 to 8.0 MeV (1975BO1H), 6.53 to 7.32 MeV (1977OH1A; α_{0}, α_{1}) and 6.0 to 18.0 MeV (1977BU07; α_{0}). A wide resonancelike structure centered at E_{p} = 13 MeV [^{12}C*(28)] with Γ ≈ 6 MeV is reported by (1977BU07): the angular distributions of α_{0} show prominent back peaking. See also (1978BU1D). Polarization measurements are reported for E_{p} = 2.62 to 2.66 MeV (1975MA49: α_{0}). (c) This reaction has been studied for E_{p} = 35.4 keV to 10.5 MeV. The total cross section has been measured for E_{p} = 35.4 to 1500 keV: it shows the 163 keV resonance and a broad peak centered at about 600 keV (σ_{max} ≈ 0.9 b; read from Fig. 3). The 163 keV resonance has σ_{R} = 54 ± 6 mb and Γ^{R}_{c.m.} = 5.2^{+0.5}_{0.3} keV, E_{res}(c.m.) = 149.8 ± 0.2 keV [E_{x} = 16.1067 (5)]. The astrophysical Sfactor and the reaction rate <σν> have been calculated. The values of <σν> obtained in this work suggest that the ^{11}B(p, 3α) reaction may be a poorer candidate for CTR than previously thought (1979DA03). At higher energy the reaction proceeds predominantly by sequential twobody decays via ^{8}Be*(0, 2.9): see in ^{8}Be (1979AJ01), ^{12}C [reaction 25] in (1975AJ02) and (1974KA1J, 1975KR1E, 1975VA04, 1977FU09, 1977GR10, 1977OH1A). Contributions from ^{12}C*(23.0, 23.6, 25.4) are also reported (1975VA04). See also (1976BO08, 1977AV01: spallation), (1977MC1C, 1977TR1E, 1978ZI1A: applications), (1974LO1B, 1976GL1E, 1979BL1J, 1979SN1A) and (1976GA1K, 1977GA1H, 1978GA13, 1979RA1J; theor.). The parameters of the observed resonances are displayed in Table 12.11 (in PDF or PS). The following summarizes the information on the lowlying resonances: for a full list of references see (1968AJ02). E_{p} = 0.16 MeV: [^{12}C*(16.11)]. This is the J^{π} = 2^{+}; T = 1 analog of the first excited states of ^{12}B and ^{12}N. The γdecay is to ^{12}C*(0, 4.4, 9.6), and also ^{12}C*(12.71) [see Table 12.8 (in PDF or PS)]: the angular distribution of γ_{3}, together with the known αdecay of ^{12}C*(9.6), fix J^{π} = 3^{} for the latter (1961CA13). A new measurement of the (p, γ) and (p, α) resonant cross sections yields 125 ± 16 μb and 38.5 ± 3.2 mb, respectively, based on Γ_{c.m.} = 6.7 keV. Γ_{γ} and Γ_{p} for ^{12}C*(16.11) are then 21.7 ± 3.3 eV and 21.7 ± 1.8 eV, respectively (1974AN19). (1977AD02) report Γ_{γ0} = 0.75, Γ_{γ1} = 16.2, and Γ_{γ7} = 0.24 eV: see, however, Table 12.8 (in PDF or PS). E_{p} = 0.67 MeV: [^{12}C*(16.58)]. The proton width [Γ_{p} ≈ 150 keV] indicates swave protons and therefore J^{π} = 1^{} or 2^{}. This is supported by the near isotropy of the two resonant exit channels, α_{1} and γ_{1}. The α_{1} cross section indicates 2J + 1 ≥ 5: therefore J^{π} = 2^{}. [This is consistent with the results of an α  α correlation study via ^{8}Be*(2.9) (1972TR07).] The γ_{1} E1 transition has M^{2} ≈ 0.1 W.u., suggesting T = 1 (1957DE11, 1965SE06). E_{p} = 1.4 MeV: [^{12}C*(17.23)]. (2J + 1)Γ_{γ0} ≥ 115 eV. This indicates J^{π} = 1^{}, with T = 1 most probable (1965SE06). J^{π} = 1^{} is also required to account for the interference at lower energies in α_{0} and γ_{0} [see (1957DE11)] and is consistent with the α  α correlation results of (1972TR07). Two solutions for Γ_{p} are possible; the larger (chosen for Table 12.11 (in PDF or PS)) is favored by elastic scattering data (1965SE06). See, however, (1975KR1E). E_{p} = 2.0 MeV: [^{12}C*(17.8)]. The resonance in the yield of α_{0} requires natural parity, the small αwidths suggest T = 1. For J^{π} = 1^{} or 3^{} the small γwidths would be surprising; J^{π} = 2^{+} would lead to a larger anomaly than is observed. J^{π} is then 0^{+}, T = 1 (1965SE06). E_{p} = 2.37 MeV: [^{12}C*(18.13)]. Seen as a resonance in the yield of 15.1 MeV γrays: σ_{R} = 0.77 ± 0.15 μb, Γ_{c.m.} = 600 ± 100 keV, (2J + 1)Γ_{γ} ≥ 2.8 ± 0.6 eV. The results are consistent with J^{π} = 1^{+}, T = 0, but interference with a nonresonant background excludes a definite assignment (1972SU08). E_{p} = 2.62 MeV: [^{12}C*(18.35)]. The resonance for α_{0} requires natural parity; the presence of a large P_{4} term in the angular distribution requires J ≥ 2 and l_{p} ≥ 2. The assignment J^{π} = 3^{} is consistent with the data (1965SE06, 1972CH35, 1972VO01, 1974GO21). E_{p} = 2.66 MeV: [^{12}C*(18.40)] is not seen here: see ^{11}B(p, p). E_{p} = 3.12 MeV: [^{12}C*(18.80)]. The angular distribution of γ_{0} indicates E2 radiation, J^{π} = 2^{+}. This assignment is supported by the angular correlation in the cascade γ_{1} and by the behavior of σ(α_{0}); T = 1 is suggested by the small Γ_{α} (1965SE06). The structure near E_{p} = 3.5  3.7 MeV [^{12}C*(19.2, 19.4)] seems to require at least two levels. The large Γ_{γ0} requires that one be J^{π} = 1^{}, T = 1 and interference terms in σ(α_{0}) require the other to have even spin and even parity: J^{π} = 2^{+}; T = 0 is favored (1963SY01, 1965SE06). Resonances at E_{p} = 4.93 and 5.11 MeV, seen in σ(γ_{1}) (1955BA22) also appear in σ(α_{1}), but not in σ(α_{0}). Angular distributions suggest J^{π} = 2^{+} or 3^{} for the latter [^{12}C*(20.64)]; the strength of γ_{1} and absence of γ_{0} favors J^{π} = 3^{}, T = 1 (1963SY01). The first seven T = 1 states in ^{12}B and ^{12}C have been identified by comparing reduced proton widths obtained for this reaction and reduced widths obtained from the (d, p) and (d, n) reactions: see Table 12.12 (in PDF or PS) (1971MO14, 1974AN19). See also (1977AD02).
Excitation functions have been reported for E_{p} = 2.6 to 11.5 MeV. They are characterized by numerous peaks: see Table 12.13 (in PDF or PS). The positions of these appear to correspond with ^{11}B(p, α)^{8}Be and with some of the (γ, n) and (γ, p) structure, suggesting that resonances, and not fluctuations, are involved. Angular distributions do not change as rapidly as might be expected from the pronounced structure in the excitation function (1965OV01). Polarization transfer coefficients for n_{0}bar have been measured for E_{pbar} = 7.3 to 14.8 MeV (1976LI08) and 16.3, 21.3 and 26.5 MeV (1976HI11). The lower energy work shows a strong peak at E_{pbar} = 9 MeV (1976LI08). (1976HI11) find that the results are not in agreement with direct reaction theory calculations using a chargeexchange effective interaction which includes both central and tensor forces. See also (1974MA07; theor.) and (1975AJ02). See also ^{11}C, (1977ME1C), (1977YO1G, 1979OV1A; applications), (1976WA1B) and (1977GA1H, 1978DE37; theor.).
Anomalies and maxima observed in the excitation functions of p_{0} and p_{1} are displayed in Table 12.13 (in PDF or PS). Recent studies are reported at E_{p} = 1.8 to 3.1 MeV (1975MA49, 1976MA64; p_{0}), E_{pbar} = 1.9 to 3.0 MeV (1977MA37; p_{0}), E_{p} = 3.0 to 5.2 MeV (1977RI01; p_{0}), 3 to 8 MeV (1975BO1H: prelim.; p_{0} → p_{3}), 7.5 to 10.5 MeV (1975VA04; p_{0}, p_{1}) and 19.2 to 47.4 MeV (1978NA03; σ_{t}). Polarization measurements have been carried out at a number of energies for E_{p} = 1.9 to 155 MeV: see (1975AJ02). (1977MO09) have observed polarization transfer in order to study the spinflip process at E_{pbar} = 32 MeV: the cross section is lower than that predicted by DWBA. See also (1975MA1H, 1976PH01, 1977PH02; theor.). For reactions (c) and (d) see ^{10}Be, ^{10}B in (1979AJ01).
Reported neutron groups are displayed in Table 12.14 (in PDF or PS). Angular distributions have been studied in the range 0.5 < E_{d} < 11.8 MeV: see (1968AJ02, 1975AJ02) for a listing of the references. See (1971MU18) for a discussion of the problems involved in comparing spectroscopic factors obtained in this reaction and in the (^{3}He, d) reaction [reaction 31]. Angular correlation studies involving ^{12}C*(4.4, 15.1) have been carried out at many energies in the range 0.7 < E_{d} < 6.3 MeV. In the range E_{d} = 1.0 to 5.5 MeV, two slow neutron thresholds are observed at 1.627 ± 0.004 MeV (E_{x} = 15.109 ± 0.005 MeV) and near 4.1 MeV (broad; E_{x} = 17.2 MeV) (1955MA76). At the lower threshold, 15.1 MeV γrays are observed: E_{d} = 1.633 ± 0.003 MeV, Γ < 2 keV (1958KA31) [E_{x} = 15.110 ± 0.003 MeV]. A study of the angular distributions and energy spectra of αparticles from the decay of ^{12}C states shows that the 12.71 and 11.83 MeV states decay sequentially via ^{8}Be; the former via ^{8}Be*(2.9), the latter 90% via ^{8}Be*(2.9) and 10% via ^{8}Be(0). There is some evidence that the 10.84 MeV state decays primarily to ^{8}Be(0). J^{π} = 3^{} for the 9.64 MeV state is favored on the basis of the angular distribution of the αparticles to ^{8}Be(0). There is no evidence for direct 3α decay of ^{12}C levels in the range E_{x} = 9 to 13 MeV, nor does ^{12}C*(10.3) appear to participate in this reaction (1965OL01). See also (1978GR07) and ^{13}C in (1981AJ01).
Observed deuteron groups are displayed in Table 12.14 (in PDF or PS). Angular distributions have been measured at E(^{3}He) = 5.1 to 44 MeV [see (1975AJ02)] and at E(^{3}He) = 23.2 MeV (1977KA1R: d to ^{12}C*(12.71, 15.11)). ^{13}N*(15.1) [T = 3/2] has been observed to decay to ^{12}C*(9.6, 10.8) with branching ratios of (9.6 ± 1.4)% and (16.4 ± 3.6)% respectively (1979AD01). See also ^{13}N in (1981AJ01).
Angular distributions have been measured at five energies in the range E_{α} = 15.1 to 46 MeV [see (1975AJ02)], at E_{α} = 25.1 MeV (1974DM01: t_{0}, t_{1}) and at 120 MeV (1979CH1R). The (t_{1}, γ) angular correlations have been measured for E_{α} = 21.2 to 25.0 MeV (1972EL09). See also (1976GU1B, 1976LE1K) and (1978ZE03; theor.).
See (1968ST12).
Angular distributions have been measured for the ground state transition at E(^{14}N) = 41, 77 and 113 MeV: they show damping of the oscillations with increasing energy (1971LI11).
Angular distributions have been measured at E(^{16}O) = 27, 30, 32.5, 35 and 60 MeV for the transitions ^{15}N_{g.s.} + ^{12}C_{g.s.}, ^{15}N*_{6.3} + ^{12}C_{g.s.}, ^{15}N_{g.s.} + ^{12}C*_{4.4} and ^{15}N_{g.s.} + ^{12}C*_{9.6} (the latter at E = 60 MeV only) (1972SC03): at the highest energy the ratio θ^{2}/θ^{2}_{g.s.} for the transition ^{11}B_{g.s.} + p → ^{12}C is 0.12 and 0.05, respectively for ^{12}C*(4.4, 9.6). See also (1975SC35) and (1974FL1A, 1975OS01, 1976DE08, 1977GO1D, 1977WE1H; theor.).
The decay is mainly to ^{12}C_{g.s.}; branching ratios to ^{12}C*(0, 4.4, 7.7, 10.3) are displayed in Table 12.15 (in PDF or PS). All the observed transitions are allowed. The halflife is 20.20 ± 0.02 msec (1978AL01). See also Table 12.2 (in PDF or PS) of (1968AJ02). ^{12}C*(7.7) is of particular interest for helium burning processes in stars [see (1968AJ02)]. The fact that the βdecay is allowed indicates J^{π} = 0^{+}, 1^{+} or 2^{+}; it decays primarily by αemission eliminating J^{π} = 1^{+}, and requiring 0^{+}. (1973BA73) have measured the Q of the αdecay of ^{12}C*(7.7) to be 379.6 ± 2.0 keV. When this result is combined with the Q determined from accurate measurements of the E_{x} of ^{12}C*(7.7), the "best" value is Q = 380.1 ± 1.1 keV. This value, together with previously measured values of Γ_{π}, Γ_{π}/Γ and Γ_{rad}/Γ lead to Γ_{rad} = 3.41 ± 1.12 meV and to a mean lifetime for the destruction of helium by the [ααα] process of 2.59 x 10^{8}ρ^{2}T^{3}_{9}exp(4.411/T^{9}) sec^{1} (1973BA73). See, however, Table 12.8 (in PDF or PS). A search for transitions to ^{12}C*(12.7) has been unsuccessful (1967AL03). (1978LE02) have measured the alignment correlation term which leads to α_{}(E_{0}) = (1 ± 2)%/MeV; (1978BR01) find α_{} = +(0.24 ± 0.44)%/MeV. The shapes of the βspectra of ^{12}B and ^{12}N have both been analyzed [see reaction 69]. The values for α_{}  α_{+} are all now in agreement with the predictions of CVC and with the absence of second class currents: see, e.g., (1977KA24, 1977SU1F, 1977WU01, 1978MO02, 1979KO12). See also (1975MI1F, 1975ST1H, 1975SU01, 1976SU1C), (1973MIYZ, 1974AD1B, 1976BE1E, 1977GA1E, 1977RI08, 1977TE1B, 1978CA1H, 1978WE1J, 1979DO1A) and (1975BE24, 1975DO10, 1975DO1D, 1975IM02, 1975KU20, 1975MO1F, 1975RH1A, 1975WI1E, 1976CA29, 1976KH05, 1976MO1G, 1976SU09, 1976YO1D, 1977AZ02, 1977BE2A, 1977CA1M, 1977HW01, 1977KU1E, 1977MA2D, 1977OK1A, 1977WA1F, 1977YA1D, 1977YO1D, 1978BE1V, 1978BE58, 1978KU1A, 1978MO02, 1978PA06, 1978SE1B, 1978SZ07, 1979DE15, 1979PR1D, 1979SZ02; theor.).
Resonance scattering and absorption by ^{12}C*(15.11) have been studied by many groups: see Table 12.15 (in PDF or PS) in (1968AJ02) and (1970AH02, 1976ME25). The partial widths are displayed in Table 12.8 (in PDF or PS). Elastic scattering to ^{12}C*(4.4, 16.1, 17.2) has also been observed. The E_{x} of ^{12}C*(4.4) is 4439.4 ± 1.6 keV (1977WE1C). Rayleigh scattering has been studied at θ = 1.02° for E_{γ} = 0.4 to 3 MeV by (1978KA1P) and nuclear Thomson scattering for E_{γ} = 5.5 to 7.2 MeV (1977BE32: θ = 140°). At higher energies elastic scattering studies show the giant resonance peak at ≈ 24 MeV. A considerable tail is visible, extending to > 40 MeV (1959PE32). See also (1975RO1N, 1976VE06, 1977CR1C, 1977HA1W, 1979KA1Q), (1975BR1F), (1975AJ02) and reaction 38.
The total absorption, mainly (γ, n) + (γ, p), is dominated by the giant resonance peak at 23.2 MeV, Γ = 3.2 MeV [σ_{max} = 21 mb (1975AH06)] and by a smaller structure at 25.6 MeV, Γ ≈ 2 MeV [σ_{max} ≈ 13 mb (1975AH06)]: see (1968AJ02, 1975AJ02) for a detailed listing of the earlier references and results. The attenuation coefficient of 6.42 MeV γrays has been measured by (1975MO27). The (γ, n) cross section shows a giant resonance centered at about 22.5 MeV, Γ ≈ 3 MeV (σ_{max} ≈ 8 mb), a secondary maximum at 25.5 MeV, Γ ≈ 2 MeV, and a long tail: see (1966FU02, 1966LO04, 1975KN10), (1975BE1F, 1976BE1H) and (1968AJ02). The (γ, n_{0}) cross section has been measured at 90° for 21 < E_{x} < 40 MeV and compared with the (γ, p_{0}) cross section (1968WU01): the isospin mixing averages about 2% in intensity and shows structure at the giant resonance. Angular distributions of n_{0} measured over the giant resonance region indicate that the main excitation mechanism is of a 1p_{3/2} → 1d_{5/2} E1 single particle character. No significant E2 strength is observed (1968RA21). See also (1975AJ02), ^{11}C and (1975SC05). The production cross section of ^{11}C by 30 MeV electrons is 11.92 ± 0.15 μb: this corresponds to an electric dipole (γ, n) integrated cross section to 30 MeV of 41.0 ± 0.6 MeV · mb (1978KL03). Pair production by 6.6 MeV γrays in carbon has been studied by (1976RO1N). The cross section for reaction (b) has been measured for E_{γ} = 35 to 130 MeV. The (γ, 2n) cross section is very much smaller than that for (γ, n): the highest value is 0.15% of the maximum value for reaction (a) in the energy range E_{γ} = 20 to 140 MeV (1970KA37). The ^{10}C production cross section has been measured for E_{bs} = 100 to 800 MeV (1977JO02). See also (1975NO10, 1975WO04, 1977BA3D, 1977HI12), (1974BU1A, 1975BE60, 1977DA1B, 1979BO1U), (1976WA1J; applications) and (1975WO07, 1976HE12, 1977GR08, 1977WU02, 1978KA1Q; theor.).
The photoproton cross section exhibits two broad peaks, the giant resonance peak at 22.5 MeV, Γ = 3.2 MeV, σ_{max} = 13.1 ± 0.8 mb and a 2 MeV broad peak at 25.2 MeV, σ_{max} = 5.6 ± 0.3 mb: see (1976CA21) and Table 12.19 (in PDF or PS) in (1968AJ02). While the E1 component dominates in the GDR, a 2% E2 contribution may possibly be present (1976CA21). In contrast with the giant resonance peak in the (γ, n) cross section, the (γ, p) cross section shows a strong peak in the center of the broad giant resonance peak. Above 24.5 MeV the ground state (γ, p) and (γ, n) excitation functions have the same shape up to at least 36 MeV (E.G. Fuller, private communication). There is agreement between the (γ, p) results and those from the inverse reaction ^{11}B(p, γ_{0})^{12}C [see reaction 27] when the population of ^{11}B*(4.4, 5.0) is taken into account. See also (1975AJ02). The fraction of transitions to the ground and excited states of ^{11}B have been determined at several energies in the range E_{bs} = 24.5 to 42 MeV: most of the transitions are to ^{11}B_{g.s.} and the excited state transitions appear to originate from localized E_{x} regions (1970ME17). The cross sections for (γ, p_{0}) and (γ, p_{0} + p_{1}) have been measured at E_{γ} = 60, 80 and 100 MeV (1976MA34). See also ^{11}B and (1978KI03). (1978BA50) have studied the momentum distribution of π^{+} and π^{} for E_{γ} = 300 to 850 MeV and (1978AR08) have measured the cross section for π^{} production in the range 510 to 750 MeV. The cross section for π^{+} production, summed over ^{12}B states, has been measured for E_{bs} to 175 MeV (1979MI06). See also the "Pion capture and pion reactions" section here, (1976BE39, 1979BO1W, 1979PA06, 1979SH1N) and (1975AJ02). See also (1975TO10, 1976KU1C, 1977AL33, 1977AL1P, 1977KI1J, 1979AL1T), (1976GA02) and (1975AN1H, 1975BI05, 1975FU07, 1976HE12, 1977FI12, 1977NE2A, 1978FI10, 1978FU09, 1978WO11; theor.).
Cross sections and angular distributions of the deuterons corresponding to transitions to ^{10}B_{g.s.} and/or low excited states have been measured at E_{γ} ≈ 40 MeV: the results are consistent with E2. There is some evidence also for the excitation of higher states of ^{10}B via nonE2 transitions (1973SK1A). For E_{bs} = 90 MeV, the ratio of yields of deuterons to protons is ≈ 2%, for particle energies 15 to 30 MeV. For higher particle energies, the ratio decreases (1962CH1B). For reaction (b) see (1975AJ02).
The yield of tritons has been measured for E_{γ} = 35 to 50 MeV by (1967KR05). For reaction (b) see (1970TA1F).
The cross section exhibits broad peaks at about 18 MeV and ≈ 29 MeV; a pronounced minimum occurs at 20.5 MeV: to what extent the peaks have fine structure is not clear: see (1964TO1A) and (1968AJ02). For E_{γ} < 22 MeV, transitions are mainly to ^{8}Be_{g.s.} and ^{8}Be*(2.9) with the g.s. transition dominating for E_{γ} ≲ 14 MeV. For E_{γ} > 26.4 MeV, ^{8}Be (T = 1) levels near 17 MeV are strongly excited (1955GO59). Alpha energy distributions show surprisingly strong E1 contributions below E_{γ} ≈ 17 MeV (1955GO59, 1964TO1A). See also (1976TU05, 1979FL1G) and (1978DZ01, 1978MY1B; theor.).
The yield of 0.48 MeV γrays from the decay of ^{7}Be, formed in reaction (b), shows a resonance at E_{γ} ≈ 29.5 MeV, σ = 0.9 ± 0.2 mb (1969OW01). For work on the γinduced spallation of ^{12}C see (1968AJ02, 1975AJ02) and (1976TU05).
The nuclear charge radius of ^{12}C, R_{rms} = 2.472 ± 0.002 fm (1979CA1G). Other values include R_{rms} = 2.445 ± 0.015 fm (Fermi model), 2.453 ± 0.008 fm (shell model) (1972JA10), 2.462 ± 0.022 fm (1973FE13), 2.45 ± 0.04 fm (1979DO1M). See also (1975AJ02). Elastic scattering has been studied up to 4 GeV: see (1968AJ02, 1975AJ02). ^{12}C states observed in inelastic scattering are displayed in Table 12.16 (in PDF or PS). The variation of the form factor F(q^{2}) with momentum transfer yields unambiguous assignments of J^{π} = 2^{+}, 0^{+} and 3^{} for ^{12}C*(4.4, 7.7, 9.6): see (1975AJ02) and (1978CR1A, 1979CR1D, 1979FL1F). The isospin mixing between the 1^{+} states ^{12}C*(12.7, 15.1) has been measured by (1974CE01): β = 0.19 ± 0.01 or 0.05 ± 0.01. See also reactions 21, 22, 50, 73, 74 and 86. A study at E_{e} = 57 to 215 MeV (θ = 180°) of the transverse form factors squared of the 2^{+} states ^{12}C*(4.4, 16.1) indicates appreciable contributions of nuclear convection currents to the T = 0 state at low momentum transfer and spin magnetization contributions to the T = 1 state at higher q (1978FL09). Longitudinal and transverse form factors of ^{12}C*(16.1) have been studied by (1978FR03) at E_{e} = 32.8 to 62.2 MeV. The ground state branching ratio for ^{12}C*(17.76) is < 10^{9} (1979CR1D). Inelastic scattering of the giant resonance has been studied by many groups: see (1968AJ02) and Table 12.16 (in PDF or PS). The longitudinal form factors show ^{12}C*(16.1, 18.6, 20.0, 21.6, 22.0, 23.8, 25.5) while the transverse form factors show ^{12}C*(15.1, 16.1, 16.6, 18.1, 19.3, 19.6, 20.6, 22.7, (25.5)) (1970AN1C, 1970TO13, 1971YA03, 1972AN03). ^{12}C*(19.3) may be the expected giant magnetic quadrupole state, J^{π} = 2^{}: see (1975AJ02). See also (1978FA1F, 1979FL1F). See also (1975BE1T, 1975LA23, 1975LU1B, 1976BU1H, 1976VL01, 1977HA1W, 1978DE32, 1979FL1E), (1974DE1E, 1975FA1A, 1975HU1D, 1977RI1H, 1979LI06, 1979BE2E) and (1974UB1A, 1974WA1C, 1975AB1E, 1975BE12, 1975BO27, 1975DO10, 1975DO1D, 1975FR05, 1975IN04, 1975KI21, 1975LA1G, 1975LE14, 1975OK1A, 1975WA30, 1975WE1A, 1976BU1B, 1976BU1G, 1976BH1B, 1976GU11, 1976KA07, 1976RA28, 1976TA1F, 1977AG03, 1977AH04, 1977BR37, 1977DE16, 1977FU1M, 1977FU1E, 1977GR02, 1977GR24, 1977GU1D, 1977RI1H, 1977VI03, 1977WA1F, 1977WA1G, 1978AL04, 1978BU1K, 1978DO1D, 1978DU12, 1978FU13, 1978GU13, 1978HO1E, 1978KO32, 1978MA1U, 1978MU04, 1978RI1C, 1978SE1B, 1978UE1B, 1979AM02, 1979CA1H, 1979FR1C, 1979GO1Q, 1979IN06, 1979KA1P, 1979KN1E, 1979PE1G, 1979PO03, 1979SA20, 1979SE06; theor.).
Electron spectra in the region of large energy loss show a broad peak which is ascribed to quasielastic processes involving ejection of single nucleons from bound shells: see (1968AJ02). Studies of e'  p coincidences for E_{e} = 497 to 700 MeV reveal peaks corresponding to ejection of 1p and 1s protons: the energy of the two peaks [Γ = 6.9 ± 0.1 and 19.8 ± 0.5 MeV] are 15.5 ± 0.1 and 36.9 ± 0.3 MeV (1976NA17: 700 MeV; DWIA). By studying the missing energy spectrum at E_{e} = 497 MeV (1976MO17) the population of ^{11}B*(2.14, 5.0) [as well as of ^{11}B_{g.s.} (1974BE12)] is reported. See also (1975AJ02) and (1977ZI1B). The deep inelastic response function has been studied by (1978MO19: E_{e} = 160 to 520 MeV, θ = 60° and 130°): a pronounced transverse strength is found in the region between the quasielastic and the N peaks. For reaction (b) see (1975WO04) and (1975AJ02). For reaction (c) see (1977SH14) and ^{12}B. For reaction (d) see (1976HE13). For both see also the "Pion capture and pion reactions" section here. See also (1977KN04, 1979FI1D, 1979FR1B, 1979PA1G, 1979PA1K, 1979SC1E, 1979SH1N, 1979ZI1D) and (1974JA1N, 1975AN1K, 1975DI1G, 1975DZ04, 1975GO33, 1975KA40, 1975RO18, 1975WO07, 1976BE60, 1976GO08, 1976NA03, 1976TA1G, 1977BE67, 1977FI12, 1977HA23, 1977KA1T, 1977MC1F, 1977NE2A, 1978FU04, 1978HA36, 1978KE1F, 1978NA20, 1978TA1D, 1979BE2F, 1979BO07, 1979FI1C, 1979KL1C; theor.).
Angular distributions of the scattering (primarily elastic at forward angles) have been measured at E_{π} = 29 MeV (1978JO09; π^{}), 29.2 and 49.5 MeV (1979GY1B; π^{}), 50 MeV (1977DY02, 1978MO25, 1979DY02; π^{+}), 120 to 280 MeV (1970BI1A; π^{}), 125 MeV (1979NA04; π^{+}), 162 MeV (1978MO23; π^{+}) and 150, 162, 226 MeV (1977PI02, 1977PI09, 1979CH05; π^{+} and π^{}). Inelastic distributions to ^{12}C*(4.4, 9.6) are reported by (1977DY02; E_{π+} = 50 MeV), (1970BI1A; E_{π} = 120 to 280 MeV; also to ^{12}C*(15.0)), (1979CH05; also to 7.7; E_{π+} = E_{π} = 162 MeV), (1978TH1C; E_{π} = 162 MeV) and (1978MO23; E_{π+} = 162 MeV; also to 19.3). Observation of 4.4 MeV γrays at E_{π} = 73 MeV leads to a cross section ratio (π^{}/π^{+}) of 1.23 ± 0.22. The cross section is 14.5 ± 3.0 mb for π^{+} (1970HI10). At E_{π+} = 148 MeV, ^{12}C*(7.6, 15.1) are also populated (1978PE11). See also (1977GR1G, 1979MO1R). (Comparison of π^{+} and π^{} inelastic scattering at E_{π} = 180 MeV shows structures at E_{x} ≈ 19.2  19.7 MeV which may be due in part to an isospinmixed 4^{} doublet (1979CO1N). Angular distributions have been reported at E_{π+} = 100 to 300 MeV for ^{12}C*(4.4, 7.7, 9.6, 19.3) (1979AL1U). Preliminary values for the isospin mixing of ^{12}C*(12.71, 15.11) and ^{12}C*(18.4, 19.4) are 125 ± 35 and 250 ± 50 keV, respectively (1979BO2D, 1979MO1W; prelim.; E_{π} = 116, 180 MeV). See also (1979CO1L).) The absorption cross section at E_{π+} = 125 MeV is 161 ± 28 mb (1979NA04). The emission of 2 photons in the capture of stopped pions, i.e. (π^{}, γγ), occurs at a rate of ≈ (1.3 ± 0.3) x 10^{5}/capture (1979DE06). See also (1977RO21, 1979MA2J). For the (π^{+}, π^{+}p) reaction see (1978CO02). For reaction (c) see (1973AS1A). See also the "Pion capture and pion reactions" section here.
Elastic and inelastic scattering to ^{12}C*(4.4, 7.7, 9.6, 10.3, 10.8, 11.8) have been studied at many energies up to 350 MeV: see (1968AJ02) and Table 12.19 (in PDF or PS) in (1975AJ02). Recent angular distribution measurements have been reported at E_{n} = 1.5 to 4.0 MeV (1975HO1G, 1978SM1D; n_{0}, natural C), 8.0 to 14.5 MeV (1978HA1P; n_{0}, n_{1}), 8.97 to 14.93 MeV (1976GL11; n_{0}, n_{1}), 14.2 MeV (1978ME12; n_{0}, n_{1}), 14.2 MeV (1978DR03; n_{1}γ) and 14.6 MeV (1975KO27; n_{0}). Angular correlations (n_{1}, γ_{4.4}) have been studied at E_{n} = 13.9 to 15 MeV: see (1975AJ02). For a brief discussion of studies of the spinflip probability for the transition to ^{12}C*(4.4) see (1975AJ02). See also ^{13}C in (1976AJ04, 1981AJ01). At E_{n} = 14.4 MeV reaction (b) involves ^{12}C*(9.6, 10.8, 11.8, 12.7): see (1975AJ02, 1976CO1N). For reaction (c) see (1978RI02). See also (1975AN1J, 1975AN1G, 1975HO1F, 1975JE01, 1975PO08, 1976HA1N, 1977WH1B), (1976MC1E, 1976WA1B, 1978FU1G) and (1976CA13, 1976TH10, 1977NO07, 1978AD1A; theor.).
Angular distributions of elastically and inelastically scattered protons have been measured at many energies up to E_{p} = 1040 MeV: see Tables 12.22 (in PDF or PS) in (1968AJ02), 12.20 (in PDF or PS) in (1975AJ02) and 12.17 (in PDF or PS) here. Table 12.18 (in PDF or PS) displays the information on excited states of ^{12}C. The newly reported value of E_{x} = 7654.00 ± 0.20 keV leads to a Qvalue for the decay of this state into 3α of 379.31 ± 0.21 keV (1976NO02) and J. Nolen, private communication): this implies an increase of 9%, at a stellar temperature of 10^{8}° K, in the 3α reaction rate calculated by (1975FO19). A summary of the information on the decays of this and other excited states of ^{12}C is shown in Table 12.8 (in PDF or PS). The spinflip probability (SFP) for the transition to ^{12}C*(4.4) has been measured for E_{p} = 15.9 to 37.6 MeV: two bumps appear at ≈ 20 and ≈ 29 MeV. It is suggested that the lower one is due to a substructure of the E1 giant dipole resonance while the upper one results from the E2 giant quadrupole resonance (1975DE32). See also the studies listed in (1975AJ02). SFP has also been measured for ^{12}C*(12.71) at E_{p} = 42 MeV (1977MO18) and for ^{12}C*(12.7, 15.1) for E_{p} = 23.5 to 27 MeV (1978HO1H). The relative population of ^{12}C*(12.7, 15.1) has been measured at E_{p} = 800 MeV, θ = 5.8°: it is roughly 1 : 2 (1978BO1Q). The angular distributions of the proton groups to ^{12}C*(4.4, 12.7, 15.1) for E_{p} = 22.5 to 45 MeV have been analyzed by (1975GE15) to obtain the structures of the giant resonances. It is suggested that the E2 strength is fragmented, with the major concentration, corresponding to the isoscalar E2 resonance, near 28 MeV, and subsidiary strength near 32 and 42 MeV, the latter possibly a part of the isovector quadrupole resonance. See also the structures reported by (1977BU19) and displayed in Table 12.18 (in PDF or PS). For polarization measurements see ^{13}N in (1976AJ04, 1981AJ01). See also (1975KA2D, 1976FR05, 1977BR33, 1977DY1C, 1977SP1D, 1979BL1G, 1979BU1D), (1975IG1A, 1976SL2A, 1977AL1U, 1977SP1B, 1978AL1G, 1978ER1C,1978IG1B, 1979LI06), (1976CR1D; astrophys.), (1978GO1E; applied) and (1974SA1G, 1974SC1E, 1975AH1C, 1975AH03, 1975AH1E, 1975BR14, 1975CL1D, 1975DU1A, 1975FR13, 1975GU11, 1975MA23, 1975NA07, 1975SC1T, 1975ST1M, 1975VI09, 1976AB05, 1976BU01, 1976HO1E, 1976KO1G, 1977AH04, 1977AL15, 1977AL19, 1977GU1D, 1977GU1E, 1977KH02, 1977KO1T, 1977NE06, 1977PH02, 1977SU1E, 1977VI03, 1977WE1K, 1978BE64, 1978BE1Y, 1978BE66, 1978CO1J, 1978FA04, 1978GU12, 1978KO32, 1978LE06, 1978MA34, 1978RA20, 1979AB01, 1979AM02, 1979BO03, 1979DY1E, 1979JA1L, 1979PE1G; theor.).
The (p, 2p) reaction has been studied at energies up to 1 GeV: see (1975AJ02) for the earlier work, ^{11}B and (1976BH02, 1977KO08, 1977NA16, 1977NA29, 1978KO30). See also (1978CH1K, 1979KR1A). For reaction (b) see (1975AJ02), (1976HO19) and ^{13}N in (1981AJ01). For reaction (c) see ^{10}B in (1979AJ01), (1977GR04) and ^{13}N in (1981AJ01). See also (1978AZ1B). For reactions (d, e) see (1976GR1H, 1977GR04). At E_{p} = 56.5 MeV reaction (f) proceeds primarily by sequential αdecay: initially ^{12}C*(19.7 ± 0.5, 21.1 ± 0.3, 22.2 ± 0.5, 26.3 ± 0.5) are formed. These states, which must therefore have natural parity and a significant T = 0 admixture, subsequently decay to ^{8}Be_{g.s.} [^{12}C*(22.2, 26.0)] or ^{8}Be*(2.9) [^{12}C*(19.7, 21.1, 26.3)] (1969EP01). At E_{p} = 100 MeV reactions (f) and (g) to ^{8}Be_{g.s.} have been studied by (1977CO07, 1977RO02): <S_{α}> = 0.59 ± 0.05 and 0.56 ± 0.12, respectively. For reaction (f) see also ^{8}Be and (1978CH1H, 1978DE1J, 1978LA11). For pion production see (1978PE12). See also (1977BA85, 1977WA05, 1978AZ02), (1975RO1B, 1977MC1F, 1977RO1E, 1975SC1V, 1978CH1C) and (1974JA1N, 1975BA1H, 1975EI1B, 1975FR06, 1975SA01, 1976BI11, 1976KO08, 1976LE02, 1977JA1F, 1977KO1P, 1978BA1C, 1978GO1L, 1978HA35, 1978TA1H, 1978WO1A, 1978WR01, 1979CH06, 1979FA1B, 1979FU1J, 1979GU1F, 1979LA02, 1979MA20; theor.).
The angular distribution of elastically and inelastically scattered deuterons has been studied at many energies up to E_{d} = 650 MeV: see (1968AJ02), Table 12.22 (in PDF or PS) in (1975AJ02) and Table 12.17 (in PDF or PS) here. E_{x} of ^{12}C*(4.4) is 4440.5 ± 1.1 keV (1974JO14). The isospin mixing of ^{12}C*(12.7, 15.1) [J^{π} = 1^{+}; T = 0 and T = 1] gives a mean charge dependent matrix element of 324 ± 33 keV (1977LI02: E_{d} = 24.1 to 28.8 MeV). See also (1976CO1Q), (1975AJ02) and reactions 21, 22, 44, 73, 74 and 86. The quadrupole deformation parameter is calculated to be β_{2} = 0.48 ± 0.02 independent of incident energy [E_{d} = 60.6, 77.3, 90.0 MeV] (1975AS06; coupled channels analysis). (1971DU09) report β_{2} = 0.47 ± 0.05 and β_{3} = 0.35 ± 0.06 for ^{12}C*(4.4, 9.6) [E_{d} = 80 MeV]. In addition to the wellknown states of ^{12}C, (1975AS06) report the population of states with E_{x} = 18.3 ± 0.3, 20.6 ± 0.3 and 21.9 ± 0.3 MeV [broad], of a broad maximum at ≈ 27 MeV, and possibly also of states at E_{x} = 10.8 ± 0.2 and 11.8 ± 0.2 MeV. (1977CH1L) report two structures at E_{x} = 26 ± 1 and 29 ± 1 MeV, with Γ = 2 ± 1 and 4 ± 1 MeV, and determine L = 3 in the excitation of ^{12}C*(18.4). Reaction (b) has been studied in a kinematically complete experiment at E_{d} = 5.00 to 5.50, 9.20 and 9.85 MeV by (1973SA03) and also at E_{d} = 5.1 to 6.5 MeV [see the discussion in (1975AJ02)]. See also ^{13}C and ^{13}N in (1976AJ04). For pion production see (1977BR33, 1978PE12). See also ^{14}N in (1976AJ04, (1981AJ01). See also (1975KI1G, 1979AZ1B), (1974AD1B, 1975SC1V) and (1974CH58, 1975GU10, 1975MA23, 1976CH03, 1977DM1A, 1977KU07, 1977VA03, 1978GH03, 1978HA1Q, 1978MA34, 1978NI1A, 1978ZE03, 1979CH06, 1979LA02; theor.). For reaction (c) see (1979HE06).
Angular distributions of elastically scattered tritons have been determined at E_{t} = 1.0 to 20.04 MeV: see (1975AJ02).
Angular distributions of ^{3}He ions have been measured in the range E(^{3}He) = 2 to 217 MeV: see (1968AJ02), Table 12.22 (in PDF or PS) in (1975AJ02) and Table 12.17 (in PDF or PS) here. Parameters of observed ^{3}He groups are displayed in Table 12.19 (in PDF or PS). Angular distributions of the ^{3}He groups to ^{12}C*(15.11, 16.11, 16.58, 19.56) have been compared with those for the tritons to ^{12}N*(0, 0.96, 1.19, 4.25) in the analog (^{3}He, t) reaction: the correspondence is excellent and suggests strongly that these are T = 1 isobaric analog states (1969BA06: E(^{3}He) = 49.8 MeV). See also Tables 12.12 (in PDF or PS) and 12.19 (in PDF or PS). The states reported by (1977BU03) at E(^{3}He) = 130 MeV [see Table 12.19 (in PDF or PS)]: ^{12}C*(4.4, 15.2, 18.4, 18.9, 21.3, 23.5, 25.9, 28.8) are all stated to correspond to E2 transitions: their strengths add up to 46% of the EWSR (energyweighted sum rule). The quadrupole deformation parameter β_{2} = 0.30 can account for both the elastic and inelastic data providing that the ratio of the s.o. and central deformation β_{s.o.}/β_{cent} is energy dependent (E(^{3}He) = 20.5  33 MeV) (1977KA25). See also (1975AJ02). For pion production see (1976WA10). See also ^{15}O in (1976AJ04, 1981AJ01), (1975AU01), (1976RO1L, 1978BE1H) and (1974CH58, 1975KU1K, 1975MA23, 1977DM1A, 1977GE1E, 1977KU07, 1978ZE03; theor.).
Angular distributions have been measured at many energies up to 1.37 GeV: see Tables 12.24 (in PDF or PS) in (1968AJ02), 12.22 (in PDF or PS) in (1975AJ02) and 12.17 (in PDF or PS) here. Parameters of observed states of ^{12}C are displayed in Table 12.19 (in PDF or PS). J^{π} assignments have also been suggested for ^{12}C states with 9.6 ≤ E_{x} ≤ 39.3 MeV on the basis of their decay into 3αparticles: see (1973JA02; E_{α} = 90 MeV). The quadrupole deformation, β_{2}, is 0.29 ± 0.02 (1971SP08), 0.30 ± 0.02 (1976PA05), 0.4 (1977BU19), 0.46 (1973SM03); β_{3} = 0.24 (1973SM03), 0.23 (1977BU19). Angular correlation measurements (α_{1}γ_{4.4}) have been carried out for E_{α} = 10.2 to 104 MeV: see (1975AJ02, 1978AL20, 1978RI03). See also (1976AL23, 1976GU1B). The relative population of magnetic substates has been studied by (1970HA15, 1972BU09). Alphaalpha correlations from ^{12}C*(14.1) to ^{8}Be_{g.s.} lead to an assignment of J^{π} = 4^{+} for that state (1977MC07). See also (1978RI03). At E_{α} = 104 MeV, the sum of the E2 strength in the dominant decay channels [α_{0} + α_{1} + p_{0}] for 20 < E_{x} < 30 MeV exhausts less than 15% of the EWSR (energyweighted sum rule) (1978RI03). At E_{α} = 150 MeV, the observed isoscalar E2 strength is (6 ± 2)% of EWSR (1976KN05). See also (1976KI1K). The yields of the 12.71 and 15.11 γrays have been measured for E_{α} = 22 to 27 MeV: strong structures are observed [see ^{16}O]. The yield of γ_{15.1} is 1 to 20% of that for γ_{12.7} (1975SP04). Measurements of the radiative widths for ^{12}C*(7.7, 9.6) are reported in Table 12.8 (in PDF or PS) (1974CH32, 1976MA46). Reaction (b) has been studied for E_{α} up to 700 MeV: see (1975AJ02). See also (1977YA1A, 1979DO04). For pion production see (1976WA10, 1977BR33, 1978PE12). For reaction (c) see (1976WO11). See also (1974YO1B, 1976YU01, 1978FR1L, 1978SH1H, 1979AR05), (1975GR41, 1975SC1V, 1976OG1A, 1976SI1E, 1977HA1P, 1977MA2E, 1977ST1G, 1978BE1H, 1978MO29) and (1974CH58, 1975CO1H, 1975GO02, 1975KU1K, 1975MA23, 1975RU10, 1975ST10, 1976AV05, 1976BA1N, 1976CU07, 1976HU07, 1976ME20, 1976PA25, 1976SA1E, 1977AL01, 1977BA12, 1977CL1D, 1977DM1A, 1977GE1E, 1977HO1H, 1977SA1P, 1977SA19, 1977TU1E, 1977VI06, 1977VI1C, 1977ZE01, 1977ZE1C, 1977ZE1D, 1978AH03, 1978FR1F, 1978FR1H, 1978SU01, 1978SU1G, 1978YO1F, 1978ZE03, 1979CH06, 1979DY1F, 1979LA02, 1979MO07; theor.).
The elastic scattering in reaction (a) has been studied at E(^{6}Li) = 4.5 to 40 MeV [see (1975AJ02)], at 4.5 to 13 MeV (1976PO02), 50.6 MeV (1976CH27) and 59.8 MeV (1975BI06; also to ^{12}C*(4.4, 7.7)), and at E(pol. ^{6}Li) = 20 and 22.8 MeV (1976WE10). See also (1977SC1B: E(^{6}Li) = 100 MeV) and (1976WE10, 1978DR07, 1978MA13) in ^{18}F (1978AJ03, 1983AJ01). (1974BI04: E(^{6}Li) = 36.4 and 40 MeV) have measured the inelastic angular distributions to ^{12}C*(4.4, 7.7, 9.6, 10.8, 11.8, 12.7, 13.4, 14.1) and have calculated deformation parameters under various assumptions. For the αdecay of ^{16}O states see (1977CU1B). The elastic scattering in reaction (b) has been studied at E(^{7}Li) = 4.5 to 36 MeV [see (1975AJ02)], at 4.5 to 13 MeV (1976PO02), 36 MeV (1976CO23) and at 89 MeV (1979BR04; also to ^{12}C*(4.4); β^{2}_{2} = 0.51 ± 0.02). See also (1978DR07) in ^{19}F (1983AJ01). See also (1971SC21, 1975GR41, 1976OG1A, 1978FI1E) and (1975TH1C, 1976AM01, 1976ST22, 1977KU07, 1978MA1B, 1978ME14, 1978NO08, 1978PE1C, 1979BE59; theor.).
Elastic scattering angular distributions have been obtained at E(^{9}Be) = 14, 20 and 26 MeV (1979JA04, 1979UN01), 39.7 and 43.8 MeV (1979MA21; also to ^{12}C*(4.4)) and at E(^{12}C) = 12, 15, 18 and 21 MeV (1970BA49). For excitation function measurements see (1978MA44); for fusion cross sections see (1978CH02). See also (1976EC1A, 1977IG1D, 1977PE1B), (1976OG1A, 1978TA1B) and (1978PA1B; theor.).
Elastic angular distributions for reaction (a) have been measured at E(^{10}B) = 18 MeV (1968VO1A, 1969VO10) and 100 MeV (1975NA15, 1977TO02; also to ^{12}C*(4.4, 9.6)). Elastic angular distributions in reaction (b) have been studied at E(^{12}C) = 15, 17, 20 and 24 MeV (1974BO15), 16, 18, 22 and 24 MeV (1975DU11) and 87 MeV (1971LI11) and at E(^{11}B) = 28 MeV (1968VO1A, 1969VO07, 1969VO10; also to ^{12}C*(4.4) as well as to several ^{11}B states). See (1978FR20) for differential cross section measurements in the range E(^{11}B) = 18.8 to 34.1 MeV and (1976ST12, 1977HI02) for fusion cross section measurements. See also (1973BR1C, 1975AJ02), (1976AR1H, 1978RO1D; astrophys.) and (1975RE04, 1978AV1A, 1978VA1A; theor.).
Angular distributions have been measured at E(^{12}C) = 10 to 20 MeV (1977HI1D, 1977KO1Q, 1977KO1W, 1978ER1D: g.s.), 10 to 37.6 MeV (1973EM03, 1975EM01: g.s. + g.s., g.s. + 4.4, 4.4 + 4.4), 17.6 to 27.5 MeV (1977CI01: g.s.), 40 to 60 MeV (1973WI09: g.s. + g.s., g.s. + 4.4), 30 to 50 MeV (1978CO20: g.s.), 70 MeV (1971KO11, 1975KO1E: g.s., 4.4, 4.4 + 4.4, 9.6), 70.7 to 126.7 MeV (1976WI14, 1977ST1Q, 1979ST10: g.s., 4.4, ((4.4 + 4.4) + 9.6)), 87 MeV (1971LI11: g.s.), 98.2 MeV (1977ST1Q: 7.65, 9.64, 14.07), and 114 and 174 MeV (1973AN22: g.s., 4.4, 7.7, 9.6, 14.1, 19.6). The relative population of elastic and inelastic channels is very energy dependent: see, e.g., (1975AJ02) and (1975EM02, 1977BR18, 1977CI01, 1977CO05, 1977CO1P, 1977KO1Q, 1977KO1V, 1977KO1X, 1978CA1K, 1978CO20, 1978ER1D, 1978JA1D, 1979CL06). Total cross sections at 1.55 and 2.89 GeV/c/A are reported by (1978JA16). See also (1976SP07, 1978CO1L, 1978KO1L, 1978SA05, 1979CO1J, 1979HA1P, 1979HE1E, 1979NA02) and (1974FO1F, 1978RO1D, 1978RO1L; astrophys.) and (1974VE05, 1975FR13, 1976AR14, 1976CU03, 1976CU07, 1976MA45, 1976ZI01, 1977AB1B, 1977BA3E, 1977CH11, 1977CI1C, 1977CL1D, 1977FI1C, 1977FR1H, 1977FR12, 1977FR1L, 1977KI1L, 1977LO1H, 1977PA28, 1977PA1H, 1977RO1K, 1977SA09, 1977SA10, 1977WA1Q, 1978AB1C, 1978AR1H, 1978AV1A, 1978BE1R, 1978BI1G, 1978CH10, 1978DA1G, 1978FI1G, 1978FR1F, 1978FR1H, 1978FR1N, 1978KO14, 1978SC1G, 1978SC1E, 1978TA13, 1978TA1P, 1978TA1B, 1978TA19, 1978TA1T, 1978TO12, 1978VA1G, 1978VA1A, 1978WI05, 1979AB02, 1979CH06, 1979CO06, 1979GO1P, 1979HA07, 1979HE1H, 1979KO11, 1979LA1L, 1979MO1J, 1979NA03, 1979PH01, 1979PI03, 1979TA02, 1979TA1K; theor.).
Angular distributions for reaction (a) have been studied at E(^{12}C) = 15, 19, 20 → 36 and 87 MeV [see (1975AJ02)] and at E(^{12}C) = 20.0 to 35.5 MeV (1978CH29: g.s. and 4.4  the latter from 30 MeV) and E(^{13}C) = 12 MeV (1976WE28, 1977GU07: g.s.) and 36 MeV (1976WE21: g.s.). Elastic angular distributions in reaction (b) are reported at E(^{12}C) = 12 to 20 MeV (1972BO68). For yield measurements see (1975AJ02) and (1976ST12, 1976WE28, 1977GE1G, 1978CH29, 1978LE1N). See also (1974GO1L, 1975VO1B, 1977WI1C), (1978RO1D; astrophys.) and (1975DE09, 1977IM1A, 1977TR1A, 1978AV1A, 1978CH30, 1978IM1A, 1978PA1B, 1978TA1B; theor.).
Angular distributions have been measured at E(^{14}N) = 21 to 88 MeV [see (1975AJ02)], 37 to 58.3 MeV (1978CO20: g.s.) and at 53 MeV (1976ZE04: g.s.), 65, 84 and 88 MeV (1971KO11, 1975KO1E: g.s., 4.4, 9.6) and 155 MeV (1975NA11, 1975NA15, 1977TO02: g.s., 4.4, 9.6). See also (1977MO1A) and ^{14}N in (1976AJ04). For fusion cross sections see (1976ST12, 1977KO1V, 1977SW02, 1978CO20, 1979GO09, 1979GO11). Reaction (b) has been studied for E(^{15}N) = 31.5 to 47 MeV (1978CO20). See also (1977PH1C). See also (1978DA1E), (1975VO1B, 1976LE1F, 1978TS04), (1978RO1D; astrophys.) and (1975DE09, 1975MO23, 1975RA33, 1976AM01, 1977BA3E, 1977MA11, 1978AV1A, 1978CU1C, 1978CU1E, 1978CU06, 1978FR1N, 1978HO13, 1978KA14, 1978VA1A, 1979NA03; theor.).
Angular distributions have been measured at E(^{16}O) = 20 to 168 MeV [see (1971AJ02, 1975AJ02, 1977AJ02)] and at E(^{16}O) = 17.29 to 23.14 MeV (1976CH13), 30.8 to 33.9 MeV (1978SC06), 31.7 to 52.7 MeV (1978JA1H; also ^{12}C*(4.4) from 46 MeV), 46 MeV (1976SP01; also involves various states in ^{16}O), 52.0 MeV (1977SH16; also excited ^{16}O states), 55.3, 56.7, 65.8 MeV (1978KA13; also excited ^{16}O states), 59.6 to 61.2 MeV (1978SH01; not g.s.: ^{12}C*(4.4)), 65 and 80 MeV (1973GU12; also ^{12}C*(4.4) and excited ^{16}O states), 84 MeV (1978BO11; only ^{12}C*(4.4)), 80 to 122 MeV (1977CO20), and at 315 MeV (1979DO01; not g.s.: ^{12}C*(4.4, 14.1, 25.3  26.7)), and at E(^{12}C) = 65 MeV (1978BO11; also ^{12}C*(4.4)) and 76.8 MeV (1977MO1A, 1977MO1H). See also (1978MA1R) and ^{16}O in (1977AJ02, 1982AJ01). (1979DO01) present evidence for the excitation of giant resonances in a number of nuclei including ^{12}C: ^{12}C*(25.3  26.7) (Γ ≈ 4 MeV) contain 25^{+15}_{10}% of the E2 strength. (1978BO11) have measured the mstate populations in the transition to ^{12}C*(4.4) at E(^{12}C) = 65 MeV and E(^{16}O) = 84 MeV. See also (1977DE1P). For reaction (b) see (1974WI05, 1979FU02, 1979SC10). See also (1975AJ02). For fusion cross section measurements see (1976CU04, 1976EY01, 1976FR20, 1976SP03, 1977BR38, 1977KO1V, 1977NA23, 1978CH15, 1978FE04, 1978TA11, 1979KO03). For other yield measurements see (1975SH24, 1976CH13, 1976SP01, 1977CO20, 1977TA03, 1978JA04, 1978KA13, 1978MA22, 1978MA32, 1978SC06, 1978SH01, 1979FR1L, 1979FU02, 1979JA1J, 1979TA05). See also (1978MA1R). A number of resonances are observed. See also ^{28}Si in (1978EN06). See also (1977QU1A, 1978CI06, 1978CL1E, 1978KA1L, 1978LA1J, 1979GA1H), (1976CU04, 1978RO1D; astrophys.), (1973BR1C, 1975GR41, 1975VO1B, 1978KO1L, 1978LE1T, 1978TS04, 1979CH07) and (1974SA1M, 1974VE05, 1975CH08, 1975VE12, 1976BA52, 1976CH1M, 1976YO01, 1977BA28, 1977BA3E, 1977CH11, 1977CL1D, 1977FR12, 1977JA1E, 1977MA1V, 1977MA1X, 1977MO1J, 1977PA1G, 1977RO1N, 1978AB1C, 1978AV1A, 1978BA53, 1978BI1G, 1978FR1N, 1978GO07, 1978MA28, 1978MA22, 1978MA50, 1978TA16, 1978TA1B, 1978VA1A, 1979KR07, 1979NA03, 1979ST1L, 1979TA07, 1979TA1K, 1979TA12; theor.)
The elastic scattering angular distributions have been measured at E(^{17}O) = 30.5 and 33.8 MeV (1978CH03) and 35 MeV (1967GO1A) and at E(^{18}O) = 32.3 and 35 MeV (1978CH03), 35 MeV (1967GO1A) and 47.5, 55 and 57.5 MeV (1976WE05). Fusion cross sections have been measured for E(^{17}O) = 16.9 to 33.8 MeV (1976EY01) and 34 to 80 MeV (1978HE18) and for E(^{18}O) = 17.5 to 35.0 MeV (1976EY01), 50 MeV (1978HE18) and 100 MeV (1978CO07). See also (1976SP07, 1978CH03, 1978FR05, 1979CH07, 1979GA1H: yieldmeasurements), (1974GO1L, 1978LE1T, 1978TS04) and (1977BA3E, 1978BI1G, 1978PA1B, 1978VA1A, 1979KR07, 1979NA03, 1979PA1B; theor.).
Elastic scattering angular distributions have been measured at E(^{19}F) = 40, 60 and 68.8 MeV (1968VO1A, 1969VO10, 1972SC03). See also (1976SP07, 1977KO38: fusion cross section at E(^{19}F) = 92 MeV), (1973BR1C, 1975GR41, 1975VO1B) and (1977BA3E, 1978BI1G, 1978HO13, 1978VA1A, 1979NA03; theor.).
Elastic angular distributions for reaction (a) have been measured at E(^{12}C) = 37 MeV (1974VA18) and E(^{20}Ne) = 65.7 MeV (1975DO06, 1978DO01). For yield measurements see (1977CO1Q, 1977PR1F, 1978DO01, 1979FO1K). See also (1977SC1G), (1978RO1L; astrophys.) and (1976VA12, 1977OS02, 1978VO06; theor.).
See (1978CL1E, 1979DA1H). See also (1978TA1B, 1979TA1K; theor.).
The angular distribution of the transition to ^{12}C*(4.4) has been measured at E(^{12}C) = 82 MeV (1977BE42). See also (1977SC1G) and (1978VA1A; theor.).
Elastic angular distributions have been studied at E(^{12}C) = 19 to 36 MeV (1977CH25), 24, 27 and 30 MeV (1977EC04), 40.2 MeV (1975RA33), 49.3, 70 and 83.5 MeV (1971KO11) and 186.4 MeV (1977DE23) and at E(^{28}Si) = 58.3 to 116.7 MeV (1978CL02, 1979OS01). For yield measurements see (1978BA02, 1978CL02, 1979KU1H). See also (1978TA1B) and (1977ZI1C, 1979TA1K; theor.).
Elastic angular distributions are reported at E(^{12}C) = 35.8 MeV (1978GE14) and E(^{32}S) = 73.3 to 128.3 MeV (1979OS01: back angles).
The elastic scattering in reactions (a), (c) and (d) has been studied at E(^{12}C) = 51.0, 49.9 and 49.9 MeV, respectively (1979RE03). See also (1979OS01). For reaction (b) see (1978BA26; theor.). For yield measurements see (1978RE06, 1979KU02, 1979RE03).
The decay is mainly to the ground state via an allowed transition. Branching ratios to other states of ^{12}C are displayed in Table 12.20 (in PDF or PS). The halflife of ^{12}N is 11.000 ± 0.016 msec (1978AL01). See also the earlier values in Table 12.28 (in PDF or PS) of (1968AJ02). Since transitions to ^{12}C*(0, 4.4) are allowed J^{π}(^{12}N) = 1^{+}. A recent measurement of the ratio of the branching ratios ^{12}N/^{12}B for the decays to ^{12}C*(4.4) is R = 1.56 ± 0.05 (1978AL01). This leads to the following values for the mirror asymmetries of ^{12}B and ^{12}N for decay to ^{12}C*(0, 4.4): δ_{4.4} = +0.044 ± 0.034, δ_{g.s.} = +0.129 ± 0.008 (1978AL01). See also (1975AJ02) for earlier measurements. These values in turn lead to second class current (SCC) contributions δ_{0}^{SCC} = 0.006 ± 0.038 and δ_{1}^{SCC} = 0.047 ± 0.037, which are consistent with zero (1978AL01). The shapes of the βspectra of ^{12}B and ^{12}N have been analyzed to give the following values for α_{}  α_{+}: (+0.98 ± 0.09)%/MeV (1977KA24), (+0.86 ± 0.24)%/MeV (1977WU01) and (+0.302 ± 0.062)%/MeV (1977SU1F). (1978BR18) find α_{+} = 0.273 ± 0.039%/MeV in agreement with the results of (1977SU1F: 0.277 ± 0.052%/MeV), These measurements are in agreement with CVC and with the absence of second class induced tensor currents. See also (1976CA29, 1978MO02, 1979KO12; theor.). See also (1975SU01, 1976SU1C, 1977DE11), (1973MIYZ, 1974AD1B, 1976BE1E, 1977GA1E, 1977RI08, 1977TE1B, 1978CA1H, 1978LE02, 1978RA2A, 1978WE1J, 1979DO1A) and (1975BE24, 1975DO10, 1975DO1D, 1975KU20, 1975MO1F, 1975RH1A, 1975WI1E, 1976KH05, 1976MO1G, 1976SU09, 1976YO1D, 1977BE2A, 1977HW01, 1977KU1E, 1977OK1A, 1977WA1F, 1977YA1D, 1978BE1V, 1978BE58, 1978KU1A, 1978MO02, 1978SE1B, 1978SZ07, 1979DE15, 1979SZ02; theor.).
The decay of the giant resonance in ^{13}C takes place predominantly to ^{12}C*(15.1, 16.1) [and their analogues in ^{12}B]. Below E_{γ} = 21 MeV transitions to ^{12}C*(0, 4.4) are dominant (1975PA09). See also (1976CR1C, 1977WO04), (1977MA06; theor.), (1975AJ02) and ^{13}C in (1981AJ01).
At E_{π+} = 34 MeV the population of ^{12}C*(4.4) is more than 10 times that of ^{12}C_{g.s.} (1978DO1F). See also (1975HU1D; theor.).
Angular distributions of the d_{0} and d_{1} groups to ^{12}C*(0, 4.4) have been measured at E_{p} = 8, 12, 17, 50 and 54.9 MeV [see (1975AJ02)], 16.7 and 17.7 MeV (1977GU14) and 200 to 500 MeV (1979KA1R). See also (1978BA1R, 1978IG1A; prelim.: 650 and 800 MeV) and (1979CA1A). Angular distributions have also been measured for the groups to ^{12}C*(12.7, 15.1, 16.1) at E_{p} = 50 MeV (1970SC02) and 54.9 MeV (1968TA08). ^{12}C*(14.1) is not excited, consistent with J^{π} = 4^{+} (1970SC02, 1974PA01). At E_{p} = 62 MeV, (1974PA01) report the excitation of states with E_{x} = 15112 ± 5, 16110 ± 5 [< 20], 17760 ± 20 [80 ± 20], 18800 ± 40 [80 ± 30], 21500 ± 100 [< 200] and 22550 ± 50 [< 200] keV [the numbers shown in brackets are Γ_{c.m.}, in keV]: l_{n} = 1 for all states except ^{12}C*(21.5) and (22.55) for which l_{p} = (1) and ≠ 1, respectively. Spectroscopic factors are derived by (1968TA08, 1970SC02, 1974PA01): see (1977AD02). In a kinematically complete experiment at E_{p} = 7.9 to 12.5 MeV, it is found that sequential decay via states in ^{13}C and ^{13}N is strongly involved in reaction (b). Near E_{p} = 12.5 MeV there is some indication of sequential decay via singlet deuteron formation (1971OT02). See also (1975AJ02), ^{13}C, ^{13}N, ^{14}N in (1981AJ01) and (1978MA34; theor.).
Angular distributions have been studied at E_{d} = 0.41 to 28 MeV [see (1975AJ02)] and at E_{dbar} = 13 MeV (1978DA17: t_{0}, t_{1}, t_{2}), E_{d} = 24.1, 26.2 and 27.5 MeV (1977LI02: t to ^{12}C*(12.71, 15.11, 16.11) and E_{dbar} = 29 MeV (1979CO08: t to ^{12}C*(0, 4.4, 12.71, 15.11, 16.11); see also ^{13}C(d, ^{3}He) in ^{12}B). (1977LI02) find an isospin mixing parameter, β, of 0.07 ± 0.03 for the two 1^{+} states ^{12}C*(12.71, 15.11) and a chargedependent matrix element of 180 ± 80 keV (1977LI02), 120 ± 30 keV (1979CO08); both are lower than the value previously obtained in this reaction, 250 ± 50 keV (1972BR27). If the j = 1/2 component is excluded, which appears to be unwarranted, the charge dependent matrix element is 140 ± 40 keV (1979CO08). See also reactions 21, 22, 44, 50, 74 and 86. See also ^{15}N in (1981AJ01) and (1975ZA06, 1977AD02).
Angular distributions have been measured at many energies up to E(^{3}He) = 45 MeV [see (1968AJ02, 1975AJ02)] and at 18 and 20 MeV (1977AD07; α_{0}, α_{1}) and 29.2 MeV (1976FU1F; α_{1}). Angular correlations of αparticles and 4.4 MeV γrays have been studied at E(^{3}He) = 4.5 MeV (1962HO13) and 29.2 MeV (1976FU1F) and for αγ_{15.1} at 9.4 and 11.2 MeV (1969TA09). A study of reaction (b) leads to Γ_{α}/Γ for ^{12}C*(15.11) = 4.1 ± 0.9%; together with the other parameters for the decay of the state (see Table 12.8 (in PDF or PS)) this leads to Γ_{α} = 1.8 ± 0.3 eV. If this isospin forbidden αwidth is the result of the mixing between the 1^{+} states ^{12}C*(12.71, 15.11) [T = 0 and 1, respectively] via a charge dependent interaction, the matrix element is 340 ± 60 keV (1974BA42). See also reactions 21, 22, 44, 50, 73 and 86. For the decay of ^{12}C*(12.7, 15.1) see Table 12.8 (in PDF or PS) (1970RE09). See also (1976ST1B, 1978SM1B) and (1977TA06; theor.).
At E(^{7}Li) = 34 MeV angular distributions have been observed for the reactions to ^{12}C*(0, 4.4) + ^{7}Li*(g.s., 0.48) and ^{8}Li*(0, 0.95) in all combinations. While ^{12}C*(0, 4.4) are dominant in the two spectra, ^{12}C*(7.7, 9.6) and, in reaction (a) at E(^{6}Li) = 36 MeV, ^{12}C*(12.7) are also populated (1973SC26).
See (1979KO1R).
Angular distributions for reaction (a) have been measured at E(^{16}O) = 13 and 14 MeV (1976DU04), 14, 17 and 20 MeV (1968KN1A, 1971BA68) and 41.7 and 46.0 MeV (1973DE21). See also (1975SE03). Angular distributions for reaction (b) are reported at E(^{17}O) = 29.8 and 32.3 MeV (1977CH22, 1978CH16) while reaction (c) has been studied at E(^{18}O) = 15, 20 and 24 MeV (1971BA68, 1971KN05) and 31.0 MeV (1978CH16). In all cases the ^{12}C_{g.s.} is involved as well as various states in the residual nucleus: see ^{13}C in (1981AJ01), ^{17}O in (1982AJ01) and ^{18}O in (1978AJ03, 1983AJ01) and ^{19}O in (1978AJ03, 1983AJ01). See also (1978PA1D, 1978SC1E; theor.).
Angular distributions have been measured at E_{p} = 14.5, 18.5 and 39.8 MeV: see (1975AJ02). At E_{p} = 54 MeV angular distributions are reported to two states at E_{x} = 27.57 ± 0.03 and 29.63 ± 0.05 MeV [Γ_{c.m.} ≲ 200 keV]: their identification as the first T = 2 states is supported by the similar angular distributions to the first two T = 2 states in ^{12}B, reached in the (p, ^{3}He) reaction [see reaction 20 in ^{12}B]. The lower T = 2 state is well fitted by L = 0; the angular distribution to ^{12}C*(29.63) is rather featureless. It is suggested that its shape is somewhat more consistent with L = 0 than with L = 2 (1976AS01). [(1976BA24) has suggested that the second T = 2 state in A = 12 may have J^{π} = 0^{+}.] It is not excluded that the group to ^{12}C*(29.63) may be due to unresolved states (1976AS01). (1976AS01) report Γ_{p}/Γ ≈ 0.3 ± 0.1 and Γ_{α1}/Γ < 0.1 for the first T = 2 state and Γ_{p}/Γ = 0.8 ± 0.2, Γ_{p0}/Γ ≈ 0.4 and Γ_{α}/Γ ≈ 0.2 for ^{12}C*(29.63). (1978RO08) report E_{x} = 27595.0 ± 2.4 keV, Γ ≤ 30 keV for the first T = 2 state and calculate the decay properties for two values of total width, 0 and 30 keV. Branching ratios for the decays to ^{8}Be(0) + α; ^{11}B*(0, 2.12, 4.45, 5.02, 6.74 + 6.79) + p; and ^{10}B(0) + d are, respectively, 10.5 ± 3.0, 3.0 ± 2.2, 8.0 ± 2.3, 0 ± 3.3, 8.4 ± 3.2, 8 ± 5, and 2.8 ± 2.0% (1979FR04).
Angular distributions leading to the ground states in reaction (a) have been measured at E(^{16}O) = 20, 25 and 30 MeV (1973SC24, 1975SC35) and 32 MeV (1968GO01: see (1975SC35)). For reaction (b) see (1972EY01). See also (1978KA23; theor.).
See ^{13}C, ^{14}N in (1976AJ04) and (1979ME1E; theor.).
Angular distributions of the t_{0} group have been measured at E_{n} = 14  15 MeV: see (1968AJ02). At E_{n} = 18.2 MeV reaction (b) takes place predominantly via sequential decay processes involving ^{12}C*(9.6, 10.8, 11.8) (1976TU04). See also ^{15}N in (1981AJ01).
See (1971WE05). See also (1976DO12; theor.).
Angular distributions have been studied at E_{p} = 7.53 to 44.6 MeV [see (1975AJ02)], at 50 MeV (1970SC02: to g.s., 4.4, 12.7, 14.1, 15.1, 16.1) and at 51.9 MeV (1976YO03: to 15.1, 16.1). The results of (1970SC02) strongly indicate J^{π} = 4^{+} for ^{12}C*(14.1). At the highest energy (1976YO03) have measured the angular distributions to the first two T = 1 states in ^{12}C and to the analog states in ^{12}N, in the (p, t) reaction. See also ^{15}O in (1981AJ01).
Observed αparticle groups are shown in Table 12.19 (in PDF or PS). Angular distributions have been measured at energies up to 28.5 MeV [see (1968AJ02, 1975AJ02)] and at E_{d} = 2.70 to 2.76 MeV (1977KO33: α_{0}, α_{1}, α_{2}), 15 MeV (1976LU1A: α_{0}, α_{1}, α_{2}) and 40 MeV (1976VA07: α_{0}, α_{1} and α to ^{12}C*(12.71, 14.08, 19.5, 20.6, 22.5)). Analysis of the angular distributions with a onestep, ZRDWBA, leads to J^{π} = (1, 2, 3)^{+}, (2, 3)^{+} and (2, 3)^{+}, respectively for ^{12}C*(19.5, 20.6, 22.5) (1976VA07: spectroscopic factors calculated for all observed transitions). For a comparison of the relative strengths of ^{12}C*(12.7, 15.1) at E_{d} = 40 MeV see (1974VA15). See also reactions 21, 22, 44, 50, 73 and 74. For reaction (b) see (1972FA07). See also ^{16}O in (1977AJ02), (1975OL1A; applications) and (1978BE1H).
See ^{16}O in (1977AJ02).
At E_{α} = 42 MeV angular distributions of ^{6}Li ions corresponding to transitions to ^{12}C*(0, 4.4) have been measured by (1964ZA1A). For reaction (b) see ^{16}O in (1977AJ02).
See (1965SH1A).
See (1976PA22). See also (1977SP06) and ^{15}N in (1981AJ01).
Angular distributions of α_{0} and α_{1} have been measured for E_{p} up to 18 MeV [see (1968AJ02)], at E_{p} = 2.99 to 5.14 MeV (1977JA11) and at six energies in the range E_{p} = 19.85 to 43.35 MeV (1971GU23). At E_{p} = 43.7 MeV the angular distributions to the 0^{+} states ^{12}C*(0, 7.65, 17.76) are fitted by L = 1, and L = 3 is consistent with the distributions to ^{12}C*(14.1, 16.1) [J^{π} = 4^{+} and 2^{+}, respectively] (1972MA21). The lifetime of ^{12}C*(4.4) τ_{m} = 65 ± 9 fsec (1970CO09). The energy of the second excited state of ^{12}C is 7654.2 ± 1.6 keV. The weighted average of this and previous values leads to E_{x} = 7654.6 ± 1.1 keV, a value which leads to a sharply reduced rate for the (ααα) process (1973MC01). See also (1966YO1A), (1977RO1H; astrophys.), (1975KU1L; theor.) and (1979ZY02) in ^{16}O in (1982AJ01).
At E_{α} = 42 MeV angular distributions have been obtained for all four of the transitions: ^{12}C_{g.s.} + ^{7}Li*(g.s., 0.48) and ^{12}C*_{4.4} + ^{7}Li*(g.s., 0.48) (1968MI05).
See (1975AJ02) and (1975SK06) in ^{16}O (1977AJ02).
For reaction (a) see (1968AJ02). Reaction (b) appears to proceed primarily via excited states of ^{13}N and ^{16}O to ^{12}C*(4.4): see (1971EP03: E_{p} = 46.8 MeV) and (1973BO1D: E_{p} = 50 MeV). See also (1975AJ02) for unpublished measurements and (1976GO1E; theor.).
Angular distributions have been measured at E_{d} = 12.7, 13.6 and 14.6 MeV (1974GA30, 1975GO09; g.s.), E_{dbar} = 16 MeV (1976JA1G; g.s.), E_{d} = 35 MeV (1975BE01, 1976NA19; g.s., 4.4), 50, 65 and 80 MeV (1978BE1T: g.s., 4.4, 14.1: ZRDWBA) and 80 MeV (1978OE02; to g.s., 4.4, 7.7, 9.6, 14.1, and broad (or unresolved) structures at 14.1 ± 2.6, 19.5 ± 1.5 MeV: ZRDWBA and FRDWBA). (1978BE1T, 1978OE02) report relative S_{α}. The relative S_{α} are strongly influenced by the choice of bound state parameters: see (1978BE1T), and compare with (1978OE02). Earlier studies at E_{d} = 14.6, 19.5, 28 and 55 MeV are listed in (1975AJ02). See also (1973FO1A, 1978BE1H), (1977KU1H, 1978TA1F; theor.) and ^{18}F in (1978AJ03).
Angular distributions have been studied at E(^{3}He) = 25.5 MeV (D. Pisano, Yale Ph.D. thesis [P.D. Parker, private communication]: ^{12}C*(0, 4.4) + ^{7}Be*(0, 0.4)), 30 MeV (1970DE12: (^{12}C*(0, 4.4, 9.6) + ^{7}Be*(0, 0.4), ^{12}C*(7.7) + ^{7}Be_{g.s.}) and at 70 MeV (1976ST11: ^{12}C*(0, 4.4) and ^{7}Be*(0, 4.4); S_{α} are calculated). In the latter experiment ^{12}C*(7.7, 9.6) are observed but they are weakly populated (1976ST11). (1975AU01) report the extraction of S_{α}, the αparticle pickup spectroscopic factor, using a FRDWBA analysis [E(^{3}He) = 26 MeV]. See also (1975AJ02).
At E_{α} = 90 MeV angular distributions involving ^{12}C*(0, 4.4) (reaction (a)) have been analyzed by PWIA and DWBA by (1976SH02): S_{α} = 2.9 ± 0.5 and 0.70 ± 0.23, respectively. At E_{α} = 65 MeV angular distributions involving ^{8}Be_{g.s.} (reaction (b)) and ^{12}C*(0, 4.4, 7.7, 9.6, 14.1) have been measured by (1974WO1C, 1976WO11) [the ground state distributions have also been studied for E_{α} = 55 to 72.5 MeV]: S_{α} = 0.25, 1.07, 0.05, 1.40 for ^{12}C*(0, 4.4, 7.7, 14.1). See also (1975AJ02) for earlier work, (1975HA1P, 1975IG1A, 1979BEZV) and (1977CH02; theor.).
See (1975SE03) and ^{17}O in (1977AJ02). See also (1973BR1C).
Angular distributions have been measured at E(^{16}O) = 23.9 MeV (1974SP06: g.s. + g.s.) and 51.5 MeV (1974RO04: ^{12}C*(0, 4.4) and various ^{20}Ne states). At E_{c.m.} = 17.5 MeV (reaction (a)) and 17 MeV (reactions (b) and (c)) angular distributions involving ^{12}C_{g.s.} (reaction (a)), ^{12}C_{g.s.} and ^{12}C*(0, 4.4) (reactions (b) and (c)) as well as a number of states in ^{20}Ne, ^{21}Ne and ^{22}Ne have been studied by (1977KA26). See reaction 25 in ^{20}Ne (1978AJ03) for additional work. See also (1978BO1R; theor.).
See (1967DE03).
The decay of the lowest T = 2 state of ^{16}O to ^{12}C*(0, 4.4) has been studied by (1973KO02). See also ^{16}O in (1977AJ02).
See (1975AJ02).
See reaction 38 in ^{20}Ne (1978AJ03).
Ground state angular distributions have been measured at E_{d} = 9 to 14.5 MeV (1964DA1B, 1967DE03, 1967DE14).
See (1967DE14).
See ^{20}F in (1978AJ03).
See (1973GA14).
See (1975AJ02) and (1978DA1F).
Angular distributions have been reported at E_{α} = 22.8 to 25.4 MeV (1978SO10) and 90 MeV (1979BEZV, 1978BE1U, 1977BE2G). See also ^{16}O in (1982AJ01).
See (1972MA36: E(^{16}O) = 42 MeV). See also (1975AJ02).
See (1979BEZV).
