(See Energy Level Diagrams for 20Ne)
Shell model: (1978WI1B, 1982BR08, 1982FL04, 1982RA1N, 1982SH30, 1983BR29, 1983DR04, 1983DR03, 1984JA15, 1984PA04, 1984RA13, 1985AN16, 1985HA15, 1985HU08, 1985MI23, 1985MU10, 1986CH28, 1986COZZ, 1986HU1G, 1986WA1R, 1987PR01).
Collective, deformed and rotational models: (1981OK02, 1982BR08, 1982RA1N, 1982RO06, 1982SC20, 1983DR04, 1983DR03, 1983LO05, 1983MA29, 1983MA68, 1983SC08, 1983VA16, 1983WA04, 1984DR01, 1984GR29, 1984KA11, 1984LO05, 1984PA04, 1984PR09, 1984RI01, 1984SA37, 1984SC41, 1985HA15, 1985LE1H, 1985OM01, 1985RO1G, 1985ST23, 1985WA08, 1986BA3P, 1986BE1D, 1986CEZW, 1986LE16, 1986SN1B, 1986STZT, 1986SU01, 1987MI07, 1987ZH1B).
Cluster and α-particle models: (1982AO06, 1982LE1P, 1982SU1B, 1983BI1F, 1983FU1D, 1983PI03, 1983MA68, 1984KA11, 1984SE20, 1984ZH07, 1985VO1E, 1986AB1H, 1986CO15, 1986GR1Q, 1986KA17, 1986KAZP, 1986LE06, 1986MAZC, 1986SU01).
Special states: (1978WI1B, 1981OK02, 1982AO06, 1982BR08, 1982FL04, 1982RA1N, 1982SC20, 1982SH30, 1982VA1E, 1983AD1D, 1983AR07, 1983BA50, 1983BI1C, 1983BR29, 1983LO05, 1983MA23, 1983VA21, 1983WA04, 1984AD1E, 1984AM03, 1984BY02, 1984DR01, 1984GR29, 1984HA14, 1984IA1A, 1984KA11, 1984RA13, 1984SA37, 1984SC01, 1984SC41, 1984SE20, 1984ZH07, 1985AD1A, 1985HA18, 1985HA1K, 1985HA15, 1985HU08, 1985LI19, 1985MI10, 1985MU10, 1985OM01, 1985RO1G, 1985VO1E, 1985WA08, 1986AN10, 1986AN07, 1986BA3P, 1986CA27, 1986CEZW, 1986CH28, 1986GR1Q, 1986HU1G, 1986KA17, 1986MAZC, 1986STZT, 1986SU01, 1986WI1P, 1987HA08, 1987IA1B, 1987KA18, 1987MI07, 1987PR01, 1987YA03).
Electromagnetic transitions and giant resonances: (1978WI1B, 1981OK02, 1982BR24, 1982RO06, 1983BA50, 1983BR29, 1983BR1P, 1983LO05, 1983VA16, 1984DR01, 1984HA14, 1984KA11, 1984LO05, 1984NA21, 1984SC01, 1984WE13, 1985AL21, 1985VE04, 1985WI17, 1986AN10, 1986CA15, 1986CA27, 1986CH28, 1986KA17, 1986KA2G, 1986KAZP, 1986SU01).
Astrophysical questions: (1981WA1Q, 1982CA1A, 1982HI1E, 1982NO1D, 1982WO1A, 1983AL23, 1983HA1P, 1983SI1B, 1983WE1A, 1984BA34, 1984CO1H, 1984TR1C, 1985AR1A, 1985DW1A, 1985NO1H, 1986MA1E, 1986TH1E, 1986TR1C, 1987BO1B, 1987CU1A, 1987MA1R, 1987ME1B, 1987MU1B, 1987PR1A).
Complex reactions involving 20Ne: (1982FA1D, 1982HO10, 1982KA33, 1982VI01, 1983BA2J, 1983DE26, 1983FR1G, 1983GA01, 1983HU1E, 1983IS1E, 1983JA05, 1983LE1F, 1983ME1R, 1983RA1E, 1983RO1H, 1983SC1M, 1983TO1H, 1983WE1C, 1983WI1A, 1984BE22, 1984DE1Q, 1984FI17, 1984GR08, 1984HO23, 1984KA1J, 1984NA12, 1984TS03, 1985AG1A, 1985BE40, 1985GAZT, 1985HA1N, 1985HO05, 1985KA1E, 1985KA1G, 1985KAZQ, 1985MC03, 1985MO08, 1985OS05, 1985SA40, 1985ST20, 1986AI1A, 1986BA1E, 1986BE2M, 1986BL06, 1986CH2G, 1986GR1A, 1986GR1B, 1986HA1B, 1986HE1A, 1986IK03, 1986MA19, 1986ME06, 1986PL02, 1986PO06, 1986SA2N, 1986SA30, 1986SC28, 1986SC29, 1986SH07, 1986SH1F, 1986SO10, 1986TR1B, 1986VA10, 1986VA18, 1986VA23, 1986WE1C, 1987FA09, 1987KO15, 1987NI04, 1987RI03, 1987RO10).
Pion and kaon capture and reactions: (1982BE1M, 1982BI08, 1982LE1P, 1982NA10, 1982OL03, 1982WO1E, 1983BA22, 1983CO08, 1983GE12, 1983GM1A, 1983MA16, 1983RA1J, 1984EF03, 1984EL1D, 1985AI1C, 1985AZ1A, 1985BI01, 1985CU1F, 1985SE21, 1986AN40, 1986BA3E, 1986LE06, 1986LE22, 1986RO03, 1986TK1C, 1987GI01, 1987SC03, 1987TE01).
Other topics: (1978WI1B, 1980KR24, 1981BL1K, 1981CL05, 1982BR08, 1982DR1E, 1982FL04, 1982GO1U, 1982VA1E, 1982VE02, 1983AR07, 1983AR1J, 1983BI1C, 1983BR29, 1983BR1P, 1983FU1D, 1983GR26, 1983IS03, 1983LO05, 1983MA23, 1983SH32, 1983VA21, 1984AM03, 1984JA15, 1984JE02, 1984KA11, 1984LO05, 1984SC41, 1985AD1A, 1985AL21, 1985AN28, 1985IV1B, 1985KA01, 1985LI19, 1985MI10, 1985MU10, 1985ST19, 1985VE04, 1986SA02, 1986TA1A, 1987HA08, 1987PR01).
Ground state of 20Ne: (1978WI1B, 1980KR24, 1982BR24, 1982FL04, 1982LO13, 1982OL03, 1982SC20, 1982ZE1A, 1983ANZQ, 1983AR07, 1983AR1J, 1983BA50, 1983BR1P, 1983DR03, 1983MA68, 1983SP04, 1983TO1L, 1983VA16, 1984AN1B, 1984BR25, 1984DR01, 1984HA14, 1984JA15, 1984KA11, 1984LO05, 1984OK04, 1984SP06, 1984WE04, 1985AN16, 1985AN28, 1985CL1A, 1985HA18, 1985HU09, 1985KR1G, 1985MI23, 1985SP06, 1986CA27, 1986LE16, 1986RO03, 1986SA02, 1986TA1X, 1987AB03).
g1.63 = +0.54 ± 0.04 (1975HO15)
Q4.25 = 0.022 ± 0.003 e2 · b2 (1978GR06)
Isotopic abundance: (90.51 ± 0.09)% (1984DE53).
Excitation functions have been measured for E(10B) = 6 to 30 MeV (reaction (a)) and 6 to 20 MeV (reaction (b)). Large resonant structures are observed in reaction (b), particularly at Ex ≈ 38 MeV (α0) and 38.6 MeV (α to 16O*(7.0, 10.3, 16.2(u)), Γ ≈ 0.6 MeV. See also (1983KAZF) and (1978AJ03).
At E(16O) = 19.5 to 42 MeV angular distributions for the 6Li ions corresponding to transitions to 20Ne*(0, 1.63, 4.25, 4.97, 5.62 + 5.79, 6.7 - 7.2) are in good agreement with Hauser-Feshbach calculations. See also (1978AJ03, 1985ST1B).
At E(11B) = 115 MeV, angular distributions are reported to 20Ne*(7.16, 8.78, 10.26, 11.95, 15.4). 20Ne*(8.78, 15.4, 17.3, 21.0 ± 0.07, 22.78 ± 0.06) are particularly strongly populated. It is suggested that these five states have Jπ = 6+, 7-, (8+), 9- and 9-: see (1983AJ01).
At E(9Be) = 16 and 24 MeV, angular distributions have been measured for 20Ne*(7.3 ± 0.4, 9.2 ± 0.4, 10.9 ± 0.3, 12.2 ± 0.3, 15.7 ± 0.3): see (1983AJ01).
At E(12C) = 45 MeV the population of states of 20Ne with Ex = 8.45, 8.78, 9.03, 10.61, 10.67, 10.99, 11.01, 11.66, 11.94, 12.14, 12.39, 12.58, 12.73, 13.05, 13.17, 13.34 [7-], 13.69, 13.91, 14.29, 14.36, 14.81, 15.17 [6+], 15.38 [7-], 15.71 [(7, 8)], 15.89 [(7)], 16.16, 16.22, 16.51 [(8)], 16.73, 17.39 [9-], 18.18 and 18.32 MeV is reported. [Values in brackets are Jπ suggested on basis of Hauser-Feshbach calculations. The underlined states are well resolved: the authors indicate ± 20 keV for such states.] The relative intensities of the groups to 20Ne*(17.39, 15.38) [Jπ = 9-, 7-] argue against the existence of a superband: see (1978AJ03). See also (1983AJ01).
Double and triple (α, α, γ) correlations and γ-ray branching measurements [see Table 20.14 (in PDF or PS)] lead to the Jπ assignments shown in Table 20.16 (in PDF or PS). See Table 20.15 (in PDF or PS) for assignments to rotational bands. Angular distributions have been reported at E(12C) = 4.9 to 51 MeV [see (1978AJ03, 1983AJ01)] and at 10.0 and 10.5 MeV (1982DA28; α0), 11.38 to 13.23 MeV (1985BA43; α0), 21 to 30 MeV (1984DH02, 1983FOZV; α0), 29.5 to 30.5 MeV (1982KA17; many states) and 35.6 to 41.2 MeV (1984LE19; many states). At E(12C) = 38 to 64 MeV, 20Ne*(7.17, 7.83, 8.54, 8.78, 9.03, 11.95, 12.13, 12.59, 13.90) are strongly populated and decay to 16Og.s. (1987RA02). For γ-decay measurements see (1987FI01), Table 20.16 (in PDF or PS) and (1978AJ03).
The yields of various groups of α-particles and their relevance to states of 24Mg, and fusion cross sections, have been studied by many groups: see (1978AJ03, 1983AJ01) for the earlier work and (1982DA28, 1982KA17, 1982SA27, 1983FOZV, 1984AR20, 1984DH02, 1984LE19, 1985BA43, 1986WU01).
See also (1982BLZT, 1983SH1Z, 1984HU1E, 1985XI1E, 1986TR08), (1981DA13, 1982CO1X, 1983SI1L, 1984CU1B), (1986SZ02; applied), (1982BA1D, 1982SA1A, 1984FO1A, 1985AR1A, 1986TH1E; astrophysics) and (1982HO05, 1982MO1V, 1982SU06, 1983AH1A, 1984DA1B, 1986FA12; theor.).
Angular distributions of the 6Li ions to many states of 20Ne below 17.5 MeV have been reported for E(14N) = 30 to 78 MeV and E(12C) = 67.2 MeV. At the latter energy 20Ne*(16.67, 17.38, 18.11, 19.16, 19.6) are particularly strongly populated: see (1978AJ03). For reaction (b) to 20Neg.s. see (1984AR20, 1986WU01). See also (1982HO1E, 1985ST1B, 1986AR04) and 6Li in (1988AJ01).
For cross sections see (1986CU02).
See reaction 8.
For yields of 1.63 MeV γ-rays see (1982DE39).
Observed resonances in the yield of capture γ-rays over the range Eα = 0.8 to 10 MeV are displayed in Table 20.17 (in PDF or PS). For a discussion of 20Ne*(11.28) [Jπ = 1+; T = 1] whose excitation is parity forbidden see (1983FI02). See also (1984BU01). Total cross sections have been measured in the range Ec.m. = 1.7 to 2.35 MeV. Assuming that S does not vary with energy over that interval, the astrophysical factor for non-resonant capture to 20Neg.s. is 0.26 ± 0.07 MeV · b. An estimate of 0.7 ± 0.3 MeV · b for S at 300 keV is deduced (1987HA24). See also Table 20.17 (in PDF or PS). For other papers on astrophysical considerations see (1982BA1D, 1982SA1A, 1984LA18, 1984NO1B, 1984TR1C, 1985AR1A, 1985TA1A, 1986DE27, 1986FI15, 1986KH1J). See also (1981KH1H, 1983BA50, 1983DE32, 1983LA25, 1984LA18, 1985BA2W, 1985BA1Q, 1986DE27; theor.).
Excitation functions have been measured over a wide range of energies for elastically and inelastically scattered α-particles and γ-rays from the decay of 16O*(6.13, 6.92, 7.13) [see (1978AJ03, 1983AJ01)] and (1986LE23; 1.8 to 4.8 MeV; α0), (1985JA17; 2.0 to 3.6 MeV; α0), (1983CA1F, 1985CA09; 9.2 to 13.5 MeV; α0), (1984LA1N, 1986LAZZ; 10.8 to 18 MeV; α1; prelim.) and (1979BI10, 1984RI06; 14.6 to 20.4 MeV; α0 → α5). See also (1983FR14, 1985ISZU) and 16O in (1986AJ04).
A number of anomalies are observed: see Table 20.18 (in PDF or PS). Kπ parameter assignments derived from this and other work are displayed in Table 20.15 (in PDF or PS) (1984RI07). See also (1983MI22). For reaction (b) see 12C in (1985AJ01). For cross sections of relevance to astrophysics for both reactions see (1985DY05; Eα = 10 to 26 MeV). For other channels see (1983AJ01). See also (1981BU27, 1983SA07, 1984BUZO, 1984SA28), (1984RE14), (1982WA1K, 1985ME1N; applications) and (1981SH1A, 1982AO06, 1982LE23, 1982SC16, 1983AO03, 1983BI1F, 1983BR1V, 1983CS02, 1983HO1D, 1983HO1F, 1983MA29, 1983MA68, 1983SM1B, 1983WA04, 1984BY02, 1984GO04, 1984OK04, 1984PR09, 1984SE20, 1984SU02, 1985MI11, 1985WA08, 1986ALZZ, 1986CEZW, 1986DE31, 1986HO33, 1986MA35, 1986SH07, 1986SU06, 1987HO1B, 1987PR01, 1987WA1B; theor.).
Deuteron groups have been observed to many states of 20Ne: see Table 20.19 (in PDF or PS). Angular distributions have been measured for E(6Li) = 5.5 to 75.4 MeV: see (1978AJ03, 1983AJ01). See also (1984MO08). Angular correlations [(d, α0) to 16Og.s.] have been measured at E(6Li) = 60, 75 and 95 MeV (1982AR20). See also (1986BE1D) and (1980GR1L, 1982ES1A, 1982GY02, 1983COZV, 1983OS03, 1983SU11, 1984GR29, 1986GR1R; theor.).
Angular distributions in reaction (a) have been measured for E(16O) = 27.1 to 46.4 MeV and for E(12C) = 22.7 to 78 MeV [see (1978AJ03, 1985AJ01)] as well as at E(12C) = 109 MeV (1984MU04, 1985MU14; 20Ne*(1.63, 4.25, 5.79, 7.16, 8.78, 10.26, 11.95, 12.59, 15.34, 15.87, 17.30, 21.08, 22.87); σ(θ) at several angles; EFR-DWBA analysis). Γα0/Γ are displayed in Table 20.19 (in PDF or PS): see (1983AJ01) and (1983SH26). Preliminary evidence for 10+ strength at Ex ≈ 28 MeV is reported by (1986ALZN). See also (1983DEZW). For reaction (b) see (1978AJ03) and (1986CA19). For reaction (c) and for a discussion of 24Mg states reached in this reaction see (1983SH26, 1984MU04). See also (1985BE37, 1987SU03) and (1986BE19; theor.).
At E(13C) = 105 MeV angular distributions to 20Ne*(1.63, 4.25, 8.78, 11.95, 15.34, 21.0) have been studied by (1979BR03): the first four states are the 2+, 4+, 6+ and 8+ members of the 0+1 band; the two higher states [Jπ = 7-, 9-] belong to the 0- band whose band head is 20Ne*(5.79). In addition distributions are reported to 20Ne*(12.59, 15.9, 17.3) [Jπ = 6+, 8+, 8+] (1979BR03). See also (1985MU14). For fusion cross sections see (1986PA10).
Angular distributions have been reported to a number of states of 20Ne at E(16O) = 23.9 to 95.2 MeV [see (1978AJ03, 1983AJ01)] and recently at E(16O) = 26, 28 and 30 MeV (1986CA24). (1983ME13) have studied the quasi-elastic spectrum at E(16O) = 50, 60, 68 and 72 MeV. For excitation functions see (1986CA24; 20Ne*(0, 1.63)). See also (1982KO1C, 1984ME10, 1985ST1B) and (1982KO1D, 1984AP03, 1984KO13; theor.).
The excitation function for α0 shows a resonance corresponding to 20Ne*(28.): see (1978AJ03). At E(pol. 3He) = 33 MeV Ay measurements have been reported for the elastic scattering [reaction (a)] (1983LE03) and for many α-groups [see 16O in (1986AJ04)] (1982KA12). For the earlier work and for other channels see (1983AJ01). See also (1985HA11, 1987CO07; theor.).
At E = 115 MeV the 8+ state at Ex = 11.95 MeV is particularly strongly populated in both reactions: see (1983AJ01).
Angular distributions have been measured for E(3He) = 2.8 to 18.3 MeV. States of 20Ne observed in this reaction are displayed in Table 20.23 (in PDF or PS) of (1983AJ01). These include a state at Ex = 16.730 ± 0.006 MeV, Γ < 20 keV: Jπ = 0+, T = 2.
Over the range Ep = 2.9 to 12.8 MeV, the γ0 and γ1 yields are dominated by the E1 giant resonance (Γ ≈ 6 MeV) with the γ1 giant resonance displaced upward in energy. Strong well-correlated structure is observed with a characteristic Γ ≈ 175 keV. Angular distributions taken over the energy range do not vary greatly with energy. They are incompatible with γ0 and γ1 coming from the same levels in 20Ne. The 90° γ0 yield for Epol. p and Ep = 3.5 to 10 MeV has been measured: the results are interpreted in terms of four primary doorway states at Ex = 16.7, 17.8, 19.1 and 20.2 MeV. See also (1985WAZV; Epol. p = 5.9 to 10.3 MeV; E2 strength; prelim.). See also (1986OUZZ).
The yield curve for 11.2 MeV γ-rays [from the decay of 20Ne*(11.23), Jπ = 1+, T = 1, to the ground state] displays a resonance at Ep = 4.090 ± 0.005 MeV [20Ne*(16.73)]. The 11.2 MeV γ-rays are isotropic which is consistent with the presumed 0+ character of this lowest T = 2 state in 20Ne: ΓpΓγ/Γ ≈ 0.5 eV. Since Γp/Γ (from the elastic scattering) is ≈ 0.1, Γγ ≈ 5 eV. For Ep = 5.65 to 6.21 MeV, the γ0 and γ1 yields are not resonant but the yield of 10.6 MeV γ-rays is resonant at 5.879 ± 0.007 MeV [Γc.m. = 9.5 ± 3 keV, Γp0Γγ/Γ ≈ 0.05 eV; Γγ ≈ 0.3 eV]. The 10.6 MeV γ-ray is due to the cascade decay of 20Ne*(18.43), Jπ = 2+; T = 2 via 20Ne*(12.22) to the 2+ state at 1.63 MeV. For the upper limits to the strengths of the transitions to various states of 20Ne from the 0+ and 2+ T = 2 states, see (1983AJ01). Resonances observed in this capture reaction are displayed in Table 20.20 (in PDF or PS). For references see (1978AJ03, 1983AJ01). See also (1987RO25; astrophysics).
The elastic scattering has been studied in the range Ep = 0.5 to 7.5 MeV and 24.9 to 46.3 MeV [see (1978AJ03)] and at Ep = 1.5 to 3.5 MeV (1985OU01, 1986OUZZ, 1986OU01). The observed anomalies are displayed in Table 20.21 (in PDF or PS).
Resonances for inelastic scattering [p1 and p2] are listed in Table 20.22 (in PDF or PS). In general the resonances observed are identical with those reported from other 19F + p reactions, although the relative intensities differ greatly. Cross sections for production of 110 and 197 keV γ-rays are reported for Ep = 0.5 to 4.3 MeV by (1986CHYY). See also (1983LE28; astrophysics) and (1986BA88). For reaction (c) see (1986KA1U; applied) and 18F.
Many resonances occur in this reaction. They are displayed in Tables 20.23 (in PDF or PS), 20.24 (in PDF or PS) and 20.25 (in PDF or PS) depending on whether they are observed in the α0 yield [Table 20.23 (in PDF or PS)], in the α1 [or απ] yield to 16O*(6.05) [Table 20.24 (in PDF or PS)] or in the α2, α3 and α4 yields [or in the yield of the γ-rays from 16O*(6.13, 6.92, 7.12) [Table 20.25 (in PDF or PS)]]. Resonances for α0 and α1 are required to have even J, even π or odd J, odd π, while the α2, α3 and α4 resonances are all odd-even or even-odd, with the exception of the T = 2 resonance.
Listings of the earlier yield studies are given in (1972AJ02, 1978AJ03, 1983AJ01). A detailed discussion of the evidence leading to many of the Jπ assignments is given in (1959AJ76). For values of θ2 see Table 20.28 (in PDF or PS) in (1978AJ03). Recent measurements are reported by (1985OU01; 1.15 to 2.1 MeV; α0 → α3) and (1984IN04; 4.15 to 13 MeV; α0 → α5). In the latter work there are no marked correlations between the different channels.
Longitudinally and transversely polarized protons with Epol. p ≈ 0.67 MeV have been used to study 20Ne*(13.48) [Jπ = 1+; T = 1] via a parity (and isospin) forbidden α-transition. The state is not excited. The upper limits for the process, and their significance in the determination of fπ, the weak pion-nucleon coupling constant, are discussed by (1983KN01, 1986KN1C). See also (1983AJ01, 1984KN1A).
The ΔEx between the 1+ and 1-, T = 1 states 20Ne*(11.26, 11.27) is 11.1 ± 0.7 keV (1983FI02). Γγ/Γα = 0.88 ± 0.05 for 20Ne*(12.22) [2+; T = 1] (1984CA08). Using (2J + 1) ΓαΓγ/Γ = 1.41 ± 0.23 eV (1980FI01), Γα = 0.32 ± 0.06 eV for 20Ne*(12.22) (1984CA08). The Γγ/Γ of 20Ne*(12.22) implies B(M1) = 0.07 W.u. for the transition from 20Ne*(18.43) [2+; T = 2]. This is much weaker than other isovector M1 transitions in 20Ne and a factor of five lower than predicted by shell model calculations: see (1984CA08).
The decay is primarily to 20Ne*(1.63) with a half-life of 11.00 ± 0.02 sec: see reaction 1 in 20F. Besides the principal decay to 20Ne*(1.63) [log f0t = 4.97], 20F also decays to 20Ne*(4.97) [Jπ = 2-] with a branching ratio of (0.0082 ± 0.0006)% (1987AL06) [log f0t = 7.20 ± 0.03; D.E. Alburger and E.K. Warburton, private communication]. The upper limit for the ground-state decay is 0.001% [log f0t > 10.5]. For other values and earlier references see Table 20.36 (in PDF or PS) in (1978AJ03). The energy of the γ-ray from 20Ne*(1.63) is 1633.602 ± 0.015 keV. Eγ for the 4.97 → 1.63 transition is 3332.54 (19) keV which gives Ex = 4966.51 (20) keV based on Ex = 1633.674 (15) keV for the first excited state. The shape of the β-spectrum is not inconsistent with the predictions of CVC. β-γ correlation measurements lead to an upper limit for the second-class current contribution to the correlation which is consistent with zero. For references see (1983AJ01); for the earlier work see (1978AJ03). See also (1985BR29, 1985GR1A) and (1983KA32, 1985YA1J; theor.).
The photoneutron cross section (bremsstrahlung photons) shows peaks at Ex = 17.78 ± 0.05, 19.00 ± 0.05, 20.15 ± 0.15 [main peak of the GDR], 22.6 ± 0.3, 24.9 ± 0.5 and 27.5 MeV [the latter three states are broad]: the integrated cross section to 28.5 MeV is 58 ± 6 MeV · mb [exhausting ≈ 20% of the dipole sum]. The cross section for (γ, Tn) using monoenergetic photons shows a structure at 18 MeV and some fluctuations atop the broad giant resonance, σmax ≈ 7 mb. The double photo-neutron cross section, σ(γ, 2n), is dominated by a single peak at ≈ 20.5 MeV, σmax ≈ 1.1 mb. For references see (1978AJ03, 1983AJ01). The significance of reaction (c) to astrophysics is discussed by (1982SA1A, 1984FO1A).
The 20Ne charge radius, < r2 > 1/2 = 3.004 ± 0.025 fm. Form factors for many excited states of 20Ne with Ex < 8 MeV have been reported: see (1978AJ03).
At Ee = 39 and 56 MeV, the 180° inelastic scattering is dominated by the transition to a Jπ = 1+, T = 1 state at Ex = 11.22 ± 0.05 MeV with Γγ0 = 11.2+2.1-1.8 eV. A subsidiary peak is observed corresponding to a state 0.35 ± 0.03 MeV higher [if Jπ = 1+ or 2+, Γγ0 = 0.65 ± 0.18 or 0.40 ± 0.13 eV]. A number of small peaks are also reported corresponding to Ex ≈ 12.0, 12.9, 13.9, 15.8, 16.9, 18.0 and 19.0 MeV. Prominent electric dipole peaks are reported at Ex = 17.7, 19.1, 20.2 and 23 MeV, in addition to weaker structures between 12.5 and 15 MeV; and prominent electric-quadrupole peaks are observed at Ex = 13.0, 13.7, 14.5, 15.0, 15.4 and 16.2 MeV and there is a broad quadrupole excitation between 16 and 25 MeV. The GDR cross scetion integrated from 11 to 25 MeV contains about 65% of the dipole EWSR while over 90% of the isoscalar quadrupole EWSR is exhausted by the strength in the region 10 - 25 MeV.
For 11 < Ex < 24 MeV only two isovector M2 transitions appear: These are to 20Ne*(11.62, 12.10) with B(M2, k)(↑) = 64 ± 13 and 56 ± 13 μ2N fm2 [orbital contributions are non-negligible]. The M1 transition to 20Ne*(11.26) is also observed but that to 20Ne*(13.48) is not: it is < 0.2 μ2N (1985RA08). For reaction (b) see (1978AJ03).
Reaction (c) has been studied in order to obtain the (γ, α0) cross section in the giant resonance region: the cross section at 90° for Ex = 15 to 24 MeV is dominated by an E1 resonance [1-; T = 1, with an admixture of T = 0 which permits the α0 decay] at Ex = 20 MeV; lesser E1 structures are reported at Ex = 16.7, 17.1, 21 and 22 MeV. A relatively strong 2+; T = 0 resonance appears at Ex = 18.5 MeV, and evidence is reported for increasing E2 strength below 16 MeV. For references see (1978AJ03). See also (1987DE43) and (1978WI1B, 1982RU05, 1983BR1P, 1983KN05, 1984AM03, 1984AM07, 1985LE1H, 1985LE14, 1985ST23, 1986BR1X, 1986KA17, 1986SH16, 1986TA1W, 1986VA12, 1987VA12; theor.).
Angular distributions of elastically scattered protons and of a number of inelastic groups have been measured for Ep = 2.15 to 65 MeV [see (1978AJ03, 1983AJ01)] and at Epol. p = 0.8 GeV (1984BL14; to 20Ne*(0, 1.63, 4.25, 8.7(u); also Ay). The latter work confirms the large hexadecapole deformation of 20Ne. At Ep = 201 MeV, probable 1+ states at Ex = 11.25 ± 0.01, 13.51 ± 0.03 and 15.72 ± 0.05 MeV are reported by (1987WI03): There does not appear to be any quenching of the M1 strength. In addition 2- states are observed at 11.58 and 12.08 MeV with B(M2) = 64 ± 13 and 56 ± 13 μ2N as is a state of unknown Jπ at Ex ≈ 17 MeV (1987WI03). See also the earlier work in (1978AJ03). For reaction (b) see (1984CA09; Ep = 101.5 MeV). See also (1983CE1A, 1986BA2U), (1986BA88) and (1982SC20, 1983SM04, 1984AM03, 1984AM07, 1985KN04; theor.).
For a study of antiproton interactions see (1986BA22).
Angular distributions have been measured at Eα = 3.8 to 155 MeV [see (1978AJ03, 1983AJ01)] and at 54.1 MeV (1987AB03; g.s.). See also (1986BU1L; Eα = 50.5 MeV). For a spallation study see (1984AN1H); for cross sections of astrophysical interest see (1984SE02). For reaction (b) see (1983AJ01). See also (1984SA28, 1986TR08), (1982VO04, 1983CH1B) and (1982JA07, 1982WA13, 1984BU1R, 1984SR01, 1985UM01, 1986GA1N, 1986KA17; theor.).
Angular distributions have been studied at E(7Li) = 36, 68 and 89 MeV: see (1983AJ01).
For pion production see (1985FR13).
Elastic angular distributions have been measured at E(10B) = 65.9 and E(11B) = 115 MeV: see (1983AJ01).
Elastic angular distributions have been obtained at E(12C) = 22.2 to 42.7 MeV and 77.4 MeV and at E(20Ne) = 65.9, 74 and 75.2 MeV [see (1978AJ03, 1983AJ01)] as well as at E(20Ne) = 72.6, 74.0 and 75.2 MeV (1982SH29). For yield, fusion, total reaction cross section and fragmentation studies see (1982KO29, 1982MO15, 1982SH29, 1984AN1H, 1984KO12, 1985FL1B, 1985OS05, 1986BL1K, 1987KO12) and (1983AJ01). For pion production see (1982AN1H, 1983AN1L). For reaction (b) see (1983AJ01), (1984RA10, 1987SI06) and 12C in (1985AJ01). See also (1985MU18), (1983HE1B, 1984FR1A, 1984HA53, 1984NA1D, 1984ST1B, 1985BE1A, 1985CU1A, 1985ST1B, 1986IK03, 1986ST1J, 1987LA05, 1987SC1D) and (1982LO13, 1983CI08, 1983TO1L, 1984HA43, 1984IN03, 1984MAZT, 1984SH1T, 1985CH11, 1985GA1G, 1985GU1J, 1985HU04, 1985KO1J, 1986GA1F, 1986GI03, 1986HA13, 1986HE1A; theor.).
Angular distributions have been studied at E(20Ne) = 50 and 94.8 MeV involving 16Og.s. and 20Ne*(0, 1.63, 4.25) [see (1983AJ01)], at E(16O) = 25.6 to 44.5 MeV (1984GA22; elastic; also to 20Ne*(1.63) at 31.3, 33.3 and 44.5 MeV)) and at E(20Ne) = 66.8, 115, 137 and 156 MeV (1983SH25; elastic). Yield and fusion cross section measurements are reported by (1982SC13, 1982SH1N, 1983BR1R, 1983SH25, 1984GA22) and in (1983AJ01). See also (1983DU13, 1986BA69, 1986ST1J, 1987SC1D) and (1983KO31, 1983MA29, 1984NI1D, 1985CH11, 1985GU1J, 1985IC01, 1985KO43, 1985KO38, 1986GA1F, 1986HE1A, 1986KO1C, 1986TA1A; theor.).
Elastic angular distributions are reported at E(20Ne) = 68, 117, 140 and 156 MeV (1983SH25). For yield and fusion measurements see (1983PO09, 1983SH25) and (1983AJ01). See also (1983RA1J, 1987SC1D) and (1983AB1G, 1983GO13, 1983SI01, 1984TO02, 1985GA1T, 1985IV1C, 1985IV1B, 1987BA1V; theor.).
Elastic angular distributions for reaction (a) have been measured at E(20Ne) = 50, 60, 80, 90 and 100 MeV [see (1983AJ01)] and at 40 MeV (1983NA04; Sα for the system 20Ne + 24Mg = 0.08 ± 0.02). For yield and fusion cross sections see (1982GR1T, 1983AL01, 1984CHZU [also reaction (b)], 1984LE06) and (1983AJ01). See also (1983BI13, 1983DU13, 1984FR1A, 1986BL08) and (1982LO13, 1983OH1C, 1985NI1C, 1987BA01; theor.).
Elastic angular distributions are reported at E(20Ne) = 55.7, 63, 125 and 151 MeV (1983NG01). For yield, fusion and evaporation residue studies see (1982MO15, 1983MO13, 1983NG01, 1985MO08, 1986GRZK, 1987JA06) and (1983AJ01). See also (1983BI13, 1983HE1B, 1984FR1A, 1984HA53, 1985ST1B, 1985TU01) and (1982LO13, 1983CI08, 1983GO13, 1983OH1B, 1984BI06, 1985HU04; theor.).
Angular distributions have been studied at E(20Ne) = 44.1 to 70.4 MeV and at 151 MeV: see (1983AJ01). For an evaporation residue study see (1982MO15). For yield and fusion measurements see (1983AJ01). The breakup of 20Ne at E(20Ne) = 92, 149 and 213 MeV involves 20Ne*(5.79, 6.73, 7.16, 8.78, 10.26, 11.95) (1986SH30). See also (1983BI13, 1983HE1B, 1984FR1A) and (1982ST08, 1983SI01, 1984GU09, 1984SH2D, 1985AN16, 1985GU08; theor.).
20Na has a half-life of 447.9 ± 2.3 msec: see reaction 1 in 20Na. It decays to a number of states of 20Ne, principally 20Ne*(1.63): see Table 20.26 (in PDF or PS). The ratio of the mirror decays 20Na β+/→ 20Ne*(1.63) and 20F β-/→ 20Ne*(1.63), (ft)+/(ft)- = 1.03 ± 0.02. β-γ correlation measurements, as in the decay of 20F, lead to an upper limit for the second-class contribution to the correlation which is consistent with zero: see (1983AJ01). β-ν-α triple correlation coefficient measurements for the transitions via the α-unstable 2+ states shown in Table 20.26 (in PDF or PS) lead to values of the isospin mixing amplitudes [and to a determination of the vector weak coupling constant] (1983CL01). See also (1987ROZZ) and (1983HA1V, 1985BR29, 1985GR1A, 1985HA1T).
The T = 1 states observed in this reaction, and ther analog states observed in 20F in the (d, 3He) reaction, are displayed in Table 20.16 (in PDF or PS) of (1978AJ03). T = 0 states are presented in Table 20.38 (in PDF or PS) of (1978AJ03).
Angular distributions have been reported at Ep = 26.9 to 43.7 MeV: see (1978AJ03, 1983AJ01). The angular distributions of the tritons to the ground state of 20Ne and to the first 0+, T = 2 state [Ex = 16.722 ± 0.025 MeV] have been fitted by L = 0 and the tritons to 20Ne*(18.4) by L = 2. The latter is the first 2+, T = 2 state. The 0+, T = 2 state [20Ne*(16.73)] decays by α0[(-6 ± 5)%], α1 + α2[(35 ± 12)%], α3 + α4[(29 ± 12)%], p0 + p1 + p2[(14 ± 9)%] and p3 + p4 + p5[(13 ± 8)%] [measured branching ratios in percent are given in the brackets] to final states in 16O and 19F. See (1978AJ03) for references and additional information.
Angular distributions have been measured at Ep = 10.0 and 45.5 MeV: see (1972AJ02). For astrophysical considerations see (1982SA1A, 1984FO1A, 1985AR1A) and (1983AJ01). See also (1985RH1A) and (1986TU1B; applied).
Angular distributions have been studied to many states of 20Ne at Ed = 28 to 80 MeV [see (1978AJ03, 1983AJ01)] and at Ed = 54.2 MeV (1984UM04; to 20Ne*(0, 1.63, 4.25, 5.62)). Table 20.35 (in PDF or PS) in (1983AJ01) displays the observed states and Sα obtained from several analyses. For newer values of Sα see (1984UM04, 1986OE01). See also (1984PA18, 1986PAZJ; theor.).