
^{14}C (1991AJ01)(See Energy Level Diagrams for ^{14}C) GENERAL: See also (1986AJ01), 2 [Electromagnetic Transitions in A = 1315] (in PDF or PS) and 14.3 [Table of Energy Levels] (in PDF or PS) here. Nuclear models: (1985KW02, 1985MI23, 1986GU1F, 1987KI1C, 1988FL1A, 1988WO04, 1989PO1K, 1989SI1D, 1989WO1E). Special states: (1985BA75, 1985GO1A, 1986AN07, 1987BL15, 1987BL18, 1987KI1C, 1989AM01, 1989RA17). Electromagnetic transitions and giant resonances: (1984VA06, 1985GO1A, 1986ER1A, 1987HO1L, 1987KI1C, 1987RA01, 1989AM01, 1989RA16, 1989SP01). Astrophysical questions: (1982WO1A, 1986CO1R, 1986HA2D, 1987HA1E, 1987MA1X, 1987MA2C, 1988AP1A, 1988AP1B, 1988BE1B, 1989BO1M, 1989GU1L, 1989KA1K, 1989ME1C, 1989ST1D, 1989WH1B, 1990OE1C, 1990TH1C). Applied work: (1985BA2G, 1985GO1R, 1986CI1B, 1986CS1B, 1986DO1M, 1986EF1A, 1986HO1L, 1986KI1J, 1986KO2A, 1986SR1B, 1986SU1H, 1987AR1N, 1987BA2M, 1987BA2N, 1987BO1U, 1987CU1E, 1987DU1G, 1987GA1E, 1987GO1W, 1987HE1F, 1987HE1G, 1987HO1J, 1987JA1G, 1987KI1I, 1987KO1T, 1987KR1O, 1987KU1C, 1987LO1E, 1987MA2E, 1987NA1N, 1987NA1O, 1987OE1A, 1987OS1F, 1987PO1K, 1987RE1H, 1987SE1D, 1987SL1A, 1987TA1K, 1987VA1S, 1988DO1D, 1988EL1C, 1988JU1B, 1988PU1A, 1988SU1E, 1989LO14, 1989MU1A, 1990DO1C, 1990SA1J). Complex reactions involving ^{14}C: (1985AL28, 1985BA2G, 1985BE40, 1985BR1F, 1985HO21, 1985KA1E, 1985KA1G, 1985KAZQ, 1985KU24, 1985KW03, 1985PO12, 1985PO11, 1985PO14, 1985SI19, 1985VI01, 1986BA26, 1986BI1A, 1986CS1A, 1986DE32, 1986HA1B, 1986IR01, 1986ME06, 1986PA1N, 1986PI11, 1986PO06, 1986PO15, 1986PR1B, 1986SO10, 1986UT01, 1987BA38, 1987BL04, 1987BUZP, 1987BU07, 1987GU04, 1987HE1H, 1987IV01, 1987NA01, 1987PO1F, 1987PO1L, 1987PR1E, 1987RI03, 1987RU1C, 1987RU1D, 1987SH04, 1987SN01, 1987VI02, 1987YA16, 1988BA01, 1988BE56, 1988BL11, 1988CA06, 1988IV1C, 1988JO1B, 1988PR1B, 1988RU01, 1988SA19, 1988SA35, 1988SA1X, 1988SH29, 1989BA92, 1989BR34, 1989BU06, 1989BU05, 1989BU1H, 1989BU1I, 1989CI03, 1989CI1C, 1989FL1A, 1989GIZV, 1989GRZQ, 1989GU1B, 1989HO16, 1989KI13, 1989MA21, 1989MA43, 1989PO1I, 1989PO18, 1989PR02, 1989PR06, 1989PR1F, 1989SA1L, 1989SA10, 1989SA45, 1989SH37, 1989TE02, 1989YO02, 1990AR1E, 1990BU09, 1990BU13, 1990HU02, 1990OG01, 1990SH01, 1990WE01, 1990YA02). Muon and neutrino capture and reactions (See also reaction 32 in (1986AJ01).): (1985KO39, 1989MU1G, 1990KO10). Pion and kaon capture and reactions (See also reactions 15, 23, 31 and 32.): (1985AL15, 1985BA1A, 1985CH1G, 1985KO1Y, 1985TU1B, 1986BA1C, 1986BE1P, 1986BO1N, 1986CE04, 1986DY02, 1986ER1A, 1986FE1A, 1986FO06, 1986GE06, 1986GI06, 1986MA1C, 1986SI11, 1986SU18, 1986WU1D, 1987BA2F, 1987BL15, 1987DOZY, 1987GI1C, 1987JO1B, 1987KA39, 1987KO1Q, 1987MI02, 1987ROZY, 1988BA2D, 1988BA2R, 1988HA37, 1988KO1V, 1988LE1G, 1988MI1K, 1988OH04, 1988OS1A, 1988PA06, 1988RO1M, 1988TI06, 1988YU04, 1989CH31, 1989DI1B, 1989DO1K, 1989JO07, 1989LE11, 1989SI1B, 1989SI1D, 1990HAZV). Hypernuclei: (1984ZH1B, 1986AN1R, 1986DA1B, 1986FE1A, 1986KO1A, 1986MA1C, 1986WU1D, 1987MI38, 1987PO1H, 1988MA1G, 1989BA92, 1989BA93, 1989DO1K, 1989GE10). Other topics: (1985AN28, 1985MA56, 1986AN07, 1987AJ1A, 1988FL1A, 1989AJ1A, 1989DE1O, 1989PO05, 1990YA01). Ground state of ^{14}C: (1985AN28, 1985GO1A, 1985MI23, 1986HE26, 1987BL18, 1987KI1C, 1987SA15, 1987VA26, 1988VA03, 1988WO04, 1988WRZZ, 1989AN12, 1989GOZQ, 1989SA10, 1989TA01, 1989WO1E).
Adopted values from (1987RA01, 1989RA16):
Q_{0} = 0.137(9) b.
The adopted value of the halflife is 5730 ± 40 y: see (1976AJ04). Using Q_{m}, log ft = 9.04 (1971GO40). For discussions of the lifetime of ^{14}C see (1959AJ76, 1970AJ04, 1976AJ04). See also (1988YA10, 1988WRZZ, 1989DO1B, 1989PO1K, 1989SA1P, 1989WO1E; theor.). For the internal bremsstrahlung spectrum see (1988RA37).
For E(^{7}Li) = 2.3 to 5.8 MeV, the cross section for emission of α_{0}, α_{1} and α_{2+3+4} is found to increase monotonically with energy. There is a report of several broad structures in the 0^{°} yield of α_{0} and α_{1} for E(^{7}Li) = 2 to 20 MeV: it is suggested that they are due to a forwarddirection cluster transfer process: see (1976AJ04) for references. For other work see (1970AJ04, 1986AJ01). For reaction (a) see also (1987SC11).
Observed proton groups are displayed in 14.5 (in PDF or PS). See also ^{15}N.
Angular distributions have been measured at E(^{7}Li) = 5.6 to 6.2 MeV for the deuterons to ^{14}C*(0, 6.09, 6.59 + 6.73, 6.90 + 7.01, 7.34, 8.32). Gamma rays with E_{γ} = 6094.5 ± 3.2, 6728.1 ± 1.4 and 7011.7 ± 5.2 keV have been reported: see (1981AJ01) for references. For τ_{m} and E_{γ} measurements see 14.4 (in PDF or PS) in (1986AJ01) and 14.4 (in PDF or PS) here (1981KO08) [see this reference for an extensive study of electromagnetic transitions in ^{14}C and ^{14}N].
For possible resonant structure in (a) see (1976AJ04). For reaction (b) see (1981AJ01, 1986AJ01). See also (1990HA46).
Angular distributions of p_{0} have been measured at E_{α} = 1.43 to 31.2 MeV: see (1976AJ04, 1981AJ01, 1986AJ01). At E_{α} = 118.1 MeV angular distributions have been studied [DWBA analysis] to ^{14}C*(6.09, 6.59, 6.73, 7.01, 8.32, 9.80, 10.43[u], 10.74, 11.38[u], 11.7[u], 14.67, 14.87, 15.20, 16.43, 16.72, 17.30, 21.40 [u?]). It is suggested that one of the states at 11.7 MeV has J^{π} = 4^{} and the other J^{π} = (1, 2, 3)^{}, and that the state at 16.43 has J^{π} = 6^{} (1987AN04). At E_{α} = 48 MeV an angular distribution is reported to a state at E_{x} = 23.288 ± 0.015 MeV with Γ_{lab} = 70 ± 3 keV. The sharpness of the state suggests that J is large, and that perhaps it is a 7^{} state (1988BR26, and J.D. Brown, private communication). A search has been made for an 8^{} state up to 26 MeV (at 20°): the upper limit for its strength is 0.2 that for the 23.29 MeV state (J.D. Brown, private communication). See also ^{15}N, (1989BR1J) and (1988CA26; astrophys.).
Below E_{x} = 10.4 MeV, ^{14}C*(6.09, 6.73, 6.90 + 7.01, 7.34, 8.32, 9.78) are observed in both reactions at E(Li) = 34 MeV (1984CL08): the states observed at higher excitation energies are displayed in 14.6 (in PDF or PS). The intensities of the ^{3}He and α groups in the two reactions are significantly different. Comparison of the angular distributions in reaction (a) and in the analog reaction ^{11}B(^{6}Li, t)^{14}N, as well as other data, leads to the assignment of analog pairs: see reaction 11 in ^{14}N. It is suggested that ^{14}C*(11.73) and not ^{14}C*(11.67) is populated in the inelastic pion scattering (1984CL08). For the earlier work on reaction (b), see (1976AJ04).
Observed proton groups are displayed in 14.7 (in PDF or PS). Angular distributions have been measured at E_{t} = 5.5 to 23 MeV [see (1981AJ01)] and at 33 MeV (1986COZO; prelim.; to ^{14}C*(6.09, 6.6[u], 7.01, 8.31, 10.5[u], 14.87, 16.43). For other results see (1986AJ01). See also ^{15}N.
At E_{α} = 65 MeV angular distributions have been measured to ^{14}C*(0, 6.73 ± 0.02, 8.40 ± 0.14, 10.69 ± 0.05, 11.69 ± 0.06[u], 14.84 ± 0.4). The two most strongly populated states (or groups of states) are ^{14}C*(6.73, 10.69). J^{π} = 1^{} and (6^{+}, 5^{}) are favored for ^{14}C*(11.69, 14.84). For the latter 4^{+} is considered to be very unlikely: see (1986AJ01). See also (1981AJ01) for the earlier work.
See (1986BA16, 1986EL1C, 1986RO1Q).
See ^{18}O in (1987AJ02).
The thermal capture cross section is 1.37 ± 0.04 mb (1982MU14). The decay is primarily to ^{14}C*(0, 6.59) [(84.0 ± 2.3)%, (8.5 ± 0.5)%, (8.5 ± 0.5)%] with weaker branches to ^{14}C*(6.09, 6.90) [(2.5 ± 0.5)%, (4.9 ± 1)%]. Gamma rays with E_{γ} = 8173.92, 6092.4 ± 0.2, 2082.6 ± 0.3, 1586.8 ± 0.2, 1273.9 ± 0.2, 808.9 ± 0.2 and 495.4 ± 0.3 keV have been observed: E_{x} = 6093.8 ± 0.2, 6589.4 ± 0.2 and 6902.6 ± 0.2 keV are reported for ^{14}C*(6.09, 6.59, 6.90). The neutron capture yield for E_{n} = 95 to 235 keV shows a resonance at E_{n} = 152 ± 1 keV, Γ_{lab} = 5 ± 1 keV: see 14.8 (in PDF or PS) in (1981AJ01). A revised value of Γ_{γ} is 2.4 ± 0.9 eV [see R.L. Macklin quoted in (1990RA03)]. A recent remeasurement of the on and offresonance capture determines the following Γ_{γ} (in meV) for the listed transitions: 8.32 → g.s. = 34^{+13}_{6}; 8.32 → 6.09 = 151^{+76}_{33}; 8.32 → 6.73 = 30^{+30}_{13}. Thus the total radition width for ^{14}C*(8.32) is 215^{+84}_{35} meV. The offresonance capture cross section is 20 ± 9 μb (1990RA03). The decrease by an order of magnitude in the Γ_{γ} of ^{14}C*(8.32) has an important bearing on nucleosynthesis and appears to significantly reduce the production of A ≥ 14 nuclei in the nonstandard Big Bang (1990RA03). Angular distributions of cross sections and A_{y} and the 90° γ_{0} cross sections have been measured in the range E_{pol. n} = 5.6 to 17 MeV. M1 resonances are indicated at E_{n} ≈ 9.2 and 10.1 MeV (Γ ≈ 200 keV) [E_{x} = 16.7 and 17.5 MeV]. σ(E2) is less than 2% of the total capture cross section for E_{n} = 5.6 to 17 MeV (1985WR01). See also (1988MA1U, 1989DE28; astrophysics) and (1985WE06, 1986HO1N, 1987LY01, 1988HO06, 1988HO1E, 1988RA10; theor.).
The coherent scattering length (thermal, bound) is 6.19 ± 0.09 fm, σ_{scatt} = 4.16 ± 0.13 b (1979KO26) [see, however, (1986AJ01)]. a_{j=1} = 5.5 ± 0.1 fm; a_{j=0} = 6.6 ± 0.4 fm: see (1987LY01). The total cross section has been measured from 0.1 to 23 MeV: see (1988MCZT, 1981AJ01). The results of an Rmatrix analysis based on σ (θ) for neutrons scattered to ^{13}C*(0, 3.09, 3.68, 3.85) for 4.5 ≤ E_{n} ≤ 11 MeV and on some other work are shown in 14.8 (in PDF or PS) (1989RE01). The cross section for reaction (b) has been studied for E_{n} = 7.5 to 14.8 MeV: see unpublished work quoted in (1987RE01). Double differential cross sections have been studied at 4.55 ≤ E_{n} ≤ 10.99 MeV: evidence is found for the excitation of ^{14}C states [E_{x} = 15.8  18.4 MeV] which decay to ^{12}C_{g.s.} via ^{13}C*(7.55) [J^{π} = 5/2^{}] (1987RE01).
For reaction (a) see ^{13}B and (1989SOZY). For reaction (b) see (1988MCZT). For reaction (c) see (1989RE01).
At E_{p} = 185 and 200 MeV the angular distributions of π^{+} and π^{} to the ground states of ^{14}C and ^{14}O are very different: see (1986AJ01). Angular distributions and A_{y} measurements have been reported at E_{pol. p} = 200 MeV by (1987KO01, 1989KO21) to ^{14}C*(0, 6.09, 6.9[u], 7.34, 8.32, 9.8[u], 10.4[u], 10.7[u], 11.7[u], (13.0, 13.6), 14.87[u], 18.5 [broad], 23.2). The latter state has an energy of 23.2 ± 0.1 MeV and Γ ≲ 85 keV: it is not clear whether this is the same state as that reported in the ^{11}B(α, p)^{14}C reaction at 23.29 MeV (Dr. S. Vigdor, private communication). A_{y} ≈ 0 at all angles for this state (1987KO01, 1989KO21). Assuming that the π^{±} groups to ^{14}C*(6.9) and ^{14}O*(6.3) correspond to single states, and that the first populates ^{14}C*(6.73) [J^{π} = 3^{}], then ^{14}O*(6.27) is assigned J^{π} = 3^{} also. A similar comparison of ^{14}C*(14.87) with ^{14}O*(14.15), and with ^{14}N*(16.91) [J^{π} = 5^{}; 1] suggests J^{π} = 5^{} for these ^{14}C and ^{14}O states (1989KO21). (1988HU04) report differential cross sections at E_{p} = 250, 354 and 489 MeV to ^{14}C*(0, 6.09, 6.7[u], 7.34, 8.32, 9.80[u], 10.5[u], 11.7[u], 14.87, 23.2) and to previously unreported states at E_{x} = 13.50 and 14.05 MeV: The (p, π^{+}) reactions show an enhancement of the σ(θ) near the invariant mass of the δ_{1232}, in contrast with the (p, π^{}) reactions. A broad structure near E_{x} = 25 MeV is also observed (1988HU06) [see also for a continuum study]. (R.D. Bent and G.M. Huber, private communication) report that, from their measurements, E_{x} = 23.2 ± 0.6 MeV and Γ_{c.m.} < 200 keV. The assignment of J^{π} = 5^{} to ^{14}N*(14.87) [see Fig. 2 of (1988HU04)] is tentative. The uncertainties in the E_{x} = 13.50 and 14.05 MeV states are ± 100 keV and their Γ_{c.m.} are < 200 keV. I am greatly indebted to Drs. Bent and Huber for their comments. See also reaction 5 in ^{14}O, (1986JA1H, 1988HU11) and (1987KU06; theor.).
Observed proton groups are displayed in 14.10 (in PDF or PS) of (1986AJ01). Recent measurements of proton groups, using a spectrograph, give E_{x} = 6094.05 ± 0.11, 6589.58 ± 0.39, 6731.58 ± 0.11, 6902.24 ± 0.18, 7011.4 ± 0.8 and 7342.65 ± 0.32 keV (1990PI05). Angular distributions have been measured at a number of deuteron energies up to 17.7 MeV: see (1981AJ01, 1986AJ01). Gamma rays are exhibited in 14.4 (in PDF or PS): studies of these, of the angular distributions analyzed by DWBA, and of pγ correlations lead to the following J^{π} assignments [see reaction 14 in (1970AJ04) for a full discussion of the evidence and a listing of the relevant references]. ^{14}C*(6.09) is 1^{} (decay is E1); ^{14}C*(6.59) is 0^{+} (internal pairs only); ^{14}C*(6.73) is 3^{} (γ_{0} is E3; l_{n} = 2); ^{14}C*(6.90) is 0^{} (no γ_{0}; 0.81 MeV cascade via 6.09 is predominantly dipole; γ_{0.8} + γ_{6.1} correlation is only consistent with J = 0, and plane polarization leads to negative parity); ^{14}C*(7.34) is 2^{} (strength of cascade decay and angular correlation results). For a study of the pair decay of ^{14}C*(6.90) [J^{π} = 0^{}] see (1986PA23). See also ^{15}N, (1987AB04) and (1985ME1E; applied). In reaction (b) at E_{t} = 38 MeV angular distributions have been studied to ^{14}C*(0, 6.09, 6.6[u], 7.0[u], 7.34, 8.32, 9.8, 10.4[u]) (1988SI08).
(1988WO10) [and see ^{5}He, reaction 9 in (1988AJ01)].
At E(^{7}Li) = 34 MeV angular distributions have been studied to ^{14}C*(0, 6.09, 6.73, 7.34): S = 1.70, 0.43, 0.59, 0.55 (1987CO16). See also (1986AJ01).
See (1986AJ01). See also (1987GR1K) and (1987TH04; theor.).
^{14}B decays primarily to ^{14}C*(6.09, 6.73): see 14.2 (in PDF or PS). The halflife is 13.8 ± 1.0 ms: see ^{14}B.
The cross sections for reactions (a) and (b) have been measured with monochromatic photons to E_{γ} = 36 MeV (and the (γ, Tn) cross section has been derived) by (1985PY01). A sharp state is observed [with σ ≈ 3 mb] at E_{x} = 11.25 ± 0.05 MeV (1985PY01) [also observed in the (γ, n_{0}) work of (1985KU01) and showing a pronounced E1M1 interference], sitting on a 1 mb tail of the GDR. The integrated value of the cross section is 1.1 ± 0.1 MeV · mb, yielding Γ_{γ0} = 12 ± 1 eV. Most of the M1 strength of the ^{12}C core is concentrated at 11.3 MeV (1985PY01). While other states on ^{14}C affect the (γ, n) cross section at higher energies there is no evidence of pigmy resonances. The next major peak is at 15.5 MeV (σ ≈ 9.1 mb), whose decay is by neutrons to ^{12}C_{g.s.}. Above 17.5 MeV the neutron decay becomes more complex (1985PY01). Reaction (b) has little strength below 23.3 MeV. Above that energy, states of ^{14}C (T_{>}) can decay to ^{13}C*(15.1) [T = 3/2], which subsequently decays by neutron emission (1985PY01). See also the (γ, n_{0}) work of (1985KU01), (1988DI02) and (1985GO1A, 1987GO09, 1987KI1C; theor.).
The charge radius of ^{14}C, r_{r.m.s.} = 2.56 ± 0.05 fm (1973KL12). At E_{e} = 37  60 MeV (θ = 180°) inelastic groups are reported to ^{14}C*(7.01, 7.34, 8.32, 9.80, 10.5, 11.31 ± 0.02, 12.96, 14.67) with the 11.3 MeV state [1^{+}, Γ = 207 ± 13 keV, Γ_{γ0} = 6.8 ± 1.4 eV] dominant (1977CR02). At E_{e} = 81.9 to 268.9 MeV (θ = 180°) (1989PL05, 1984PL02) find the dominant strength to be to 4 states at 11.7, 17.3 and 24.4 MeV [± 0.1 MeV]. The first two of these are T = 1 states reported in the (π, π) reaction below, the third is suggested to have T = 2 (and to be unresolved from a 2^{} state). The M4 form factors account for 41% and 37% of the T = 1 and T = 2 singleparticle (e, e') cross section, respectively. The observed transitions to the T = 1 states exhaust 33  45% of the total isovector transition strength and 1  15% of the isoscalar transition strength. Magnetic electron scattering is most sensitive to isovector transitions (1984PL02). The population of ^{14}C*(6.1, 6.7, 7.0, 8.3, 9.84 ± 0.05, 10.50 ± 0.05, 12.2 ± 0.1, 12.9 ± 0.1, 13.6 ± 0.1, 14.0 ± 0.1, 14.9 ± 0.1, 15.2 ± 0.1, 16.5 ± 0.1, 22.1 ± 0.1) is also reported (1989PL05, 1984PL02). See also (1987DE43, 1986HI06, 1989AJ1A) and (1986LI1C, 1987GO08, 1987KI1C, 1987LI30, 1988CL03, 1988HO1E, 1990CL02, 1990GA1M; theor.).
Elastic angular distributions have been measured at E_{π±} = 50 MeV (1985MI16), 65 and 80 MeV (1983BL11) and 164 MeV (1986HA2E). At E_{π±} = 164 MeV, the differential cross sections for the transition to ^{14}C*(7.01) [J^{π} = 2^{+}_{1}] are nearly the same for π^{+} and π^{}. Angular distributions have also been studied to the 2^{+}_{2} state, ^{14}C*(8.32), and to an unresolved group at E_{x} = 10.4 MeV [the latter results are consistent with J^{π} = 3^{} distribution] (1988HA14) [see for discussion of B(E2)]. In earlier work at E_{π±} = 164 MeV angular distributions had been obtained to states at E_{x} = 6.7, 11.7, 15.2, 17.3 MeV [± 0.1 MeV] with J^{π} = 3^{}, 4^{}, 4^{}, 4^{}. In addition a broad structure (Γ ≈ 1.7 MeV) had been observed near 24.5 MeV. It may include a narrower peak at 24.4 MeV (1985HO07): see also the Erratum (1990HO1C). The population of ^{14}C*(6.1, 12.6) has also been reported: see (1986AJ01). See also (1989AJ1A).
At E_{p} = 497 MeV ^{14}C*(11.7, 17.3) [J^{π} = 4^{}] are populated (1989CRZX; prelim.). Elastic angular distributions are reported at E_{p} = 35 and 40.1 MeV (1990YA01). See also (1981AJ01, 1986AJ01) [the work quoted in (1986AJ01) has not been published.]
Elastic angular distributions have been studied at E(^{3}He) = 4.5 to 18 MeV [see (1976AJ04)], at 22 MeV (1988AD1B; prelim.) and 72 MeV (1988DE34, 1989ER05) and at 39.6 MeV (1987BUZR; prelim.). See also (1989DE1Q, 1989GA1I) and (1986ZE04; theor.).
Elastic angular distributions have been studied at E_{α} = 22, 24 and 28 MeV [see (1976AJ04)] and at E_{α} = 35.5 MeV (1984PE24). At the latter energy many inelastic groups have also been studied: see 14.9 (in PDF or PS) (1984PE24). See also ^{18}O in (1987AJ02) and (1985UM01; theor.).
Elastic angular distributions have been obtained at E(^{6}Li) = 93 MeV (1986BR33, 1987DE02, 1988DE47, 1989DE34) and 210 MeV (1987WI09; forward angles).
The elastic scattering for reaction (a) has been studied at E(^{14}C) = 20 to 40.3 MeV (1986STZY; prelim.) and 31 to 56 MeV (1985KO04); that for reaction (b) has been studied at E(^{13}C) = 20 to 27.5 MeV (1988BI11) [see also reaction 50 in ^{13}C]; and that for reaction (c) is reported at E(^{14}C) = 31 to 56 MeV: see (1986AJ01). For the earlier work see (1976AJ04). For yield and fusion studies see (1986AJ01) and (1986STZY). The yields of γrays from ^{14}C*(6.73) [J^{π} = 3^{}] have been measured for E(^{14}C) = 25 to 70 MeV: see (1986AJ01). See also (1990VO1E) and (1986BA69; theor.).
See (1986BA69; theor.).
The elastic scattering has been studied in reaction (a) at E(^{16}O) = 20, 25 and 30 MeV [see (1981AJ01)] and at E(^{14}C) = 20 to 43 MeV (1986STZY; prelim.); that for reaction (c) has been studied for E(^{14}C) = 20 to 30 MeV (1986STZY). The αbreakup in reaction (c) is being investigated at E(^{18}O) = 33.5 to 64 MeV (1988AL1F; prelim.). For excitation functions see (1986AJ04) and (1986STZY). See also (1989CI1C) and (1986BA69; theor.).
Differential cross sections to ^{14}C_{g.s.} have been measured at E_{γ} = 173 MeV (1985RO05, 1987RO23), at 200 MeV (1985CO15), at 230, 260 MeV and 320 MeV (1986TE01, 1990GH01) and at 320 and 400 MeV (1990DI1D; prelim.). The transitions to the 2^{+} states at 7.01 + 8.32[u] and 10.7 MeV have been studied by (1987SU17) [see for B(M1)]. See also (1985BE1K, 1987HU01, 1987YA1J), (1986WI10, 1988TI06, 1990ER03; theor.) and the "GENERAL" section.
The photon spectrum from stopped pions is dominated by peaks corresponding to ^{14}C*(6.7 + 6.9 + 7.0[u], 8.32, 10.7) and branching ratios have been obtained for these and the g.s. transition. That to ^{14}C*(6.7 + 6.9 + 7.0) is (6.22 ± 0.40)% (absolute branching ratio per stopped pion) (1986PE05). For the earlier work see (1981AJ01). See also the "GENERAL" section.
The p_{0} angular distribution has been measured at E_{n} = 14 MeV: see (1981AJ01). At E_{n} = 60 MeV the strongest transitions are to ^{14}C*(7.0 + 8.3, 11.3, 15.4) and to the giant resonanace peak, centered at ≈ 20.4 MeV, and angular distributions have been studied to these groups: see (1986AJ01). For cross sections of astrophysical interest see ^{15}N. A study of Podd and leftright asymmetries with polarized thermal neutrons is reported by (1988AN19). See also (1986BO1K, 1988EL1C; applied).
Angular distributions have been measured at E_{pol. d} = 70 MeV to ^{14}C*(7.0[u], 8.3). The ground state is very weakly populated (1986MO27). See also (1988HE1I).
At E_{t} = 33.4 MeV ^{14}C*(0, 6.09, 6.73, 7.34, 8.32) are populated (1988CL04).
See (1986GO1B; prelim.; E(^{14}N) = 150 MeV).
See (1981AJ01), ^{15}N and (1988GOZM; theor.).
The parameters of ^{14}C states observed in this reaction are displayed in 14.9 (in PDF or PS) of (1976AJ04).
At E(^{6}Li) = 93 MeV ^{14}C*(0, 7.01, 8.32, 10.45) are populated, the first two of these strongly: see (1981AJ01).
