(See Energy Level Diagrams for 20Ne)
Shell model: (CR70A, DE71AA, RA71M, ZO71B, AB72E, AR72Q, AS72A, BO72M, BR72O, JA72S, KA72C, KA72J, KH72, KR72C, KU72G, LE72I, LE72Q, MA72C, NI72E, RE72B, SA72E, VO72D, WH72A, CO73K, DH73, EL73, EN73A, GI73A, HA73F, HE73N, IC73, IR73A, MA73W, MC73B, MC73I, ME73C, PA73G, PU73A, SM73C, SV73, YA73, AY74A, KH74B, KR74C, BA75I, DR75, GI75, GR75H, HA75W, HA75Z, MP75, MU75C, TA75H, NG76, PO76, SC76J, SH76D, CA77C, FE77B, HA77S, MA77J, NE77B, RO77, SH77C).
Collective and deformed models: (CR70A, FL70A, RA71M, BO72M, DE72U, HA72II, HI72J, HO72F, HO72P, JA72S, KU72G, TE72A, VO72D, CA73C, CU73, DE73L, EL73, GO73J, HO73N, HO73U, HO73V, IC73, IR73A, KO73E, KR73D, LA73T, MC73I, MI73M, NG73A, NO73B, RE73E, SE73I, ST73R, SV73, VA73O, YA73, AR74C, KR74C, MA74F, MP74, NO74I, RI74B, SC74M, TA74, AB75, BU75L, DR75, GR75H, HA75W, HE75A, HE75E, HO75M, MA75K, NE75B, TA75H, BA76D, CH76O, JA76C, KE76, MA76U, NO76G, PA76A, SH76D, ST76D, UL76, CA77C, FE77B, HO77M, KA77N, MA77J, PA77A, RO77L, ST77J, TH77A).
Cluster and α-particle models: (AB71A, AR71T, RI71G, SA71J, WO71F, AR72E, AR72Q, BA72S, FR72C, GO72J, GR72O, HI72J, HO72P, IK72A, KA72C, KA72J, LA72F, LI72J, NE72B, VO72D, AR73R, CH73E, CU73, HO73N, HO73U, IC73, KR73D, LA73T, MA73EE, SU73B, VA73K, YA73, AB74, GO74I, MO74, YA74B, AR75J, BU75A, BU75L, HA75Z, HE75A, HE75E, IK75, MA75K, NE75B, BA76D, BA76G, FU76I, KI76C, SA76O, FL77D, FU77E, HE77D, HO77L, HO77M, KA77N, RO77L, ST77J, TO77E).
Astrophysical questions: (CL72D, KO72J, AR73O, AR73Q, AU73C, CA73O, CO73EE, HO73DD, RA73F, AR74H, AR74J, PA74F, BA75V, EN75B, IB75A, LA75B, MA75BB, PE75B, RA75C, RO75G, TA75I, TR75D, WO75C, GI76C, NO76L, RO76D, RU76, SI76G, AR77A, BU77H, CA77N, DW77A, KI77, PA77C, VO77).
Electromagnetic transitions: (DE71AA, AB72E, AS72A, BE72U, BO72M, DE72U, HA72II, HI72J, LE72Q, LO72H, MA72E, TR72B, CA73C, CU73, EL73, GO73J, HA73R, HA73BB, HA73MM, HO73V, LE73M, PU73A, ST73R, UN73, AB74, HA74Q, HA74W, KH74B, MA74F, MC74G, NO74I, SC74M, BU75A, BU75L, MA75K, NA75M, NA75N, TA75H, BA76D, FU76I, SC76J, VO76C, HO77M, KN77E, MA77J, NE77B, RO77, SC77A).
Special levels: (AR72E, BE72U, FO72G, HA72LL, HI72J, JA72S, KH72, LE72I, MA72C, MA72E, NI72E, SA72, TE72A, CH73E, CU73, DH73, EN73A, HO73U, IR73A, JU73E, KO73M, MA73EE, MC73B, MI73M, NO73B, PU73A, SU73B, UN73, YA73, AR74C, GO74I, GO74V, HA74Q, IT74, KH74B, KR74C, MA74V, MO74, AR75J, BA75I, BU75A, BU75L, HA75Z, MA75B, MA75EE, MI75B, NA75M, NE75B, BA76D, SA76J, SC76J, CA77C, FU77E, HA77S, NE77B, SC77A, SH77C, ST77J).
Applied work: (CH76U).
Other topics: (FU69H, RA71M, ZO71B, AB72E, BR72O, EL72, FR72C, GR72B, GR72K, JA72S, KA72J, KH72, KR72A, KR72C, LA72F, MU72E, NI72E, PA72N, PL72A, RE72B, SA72, SA72E, SH72L, TE72A, BE73BB, CA73I, CO73K, CU73, EL73, ER73D, FO73I, GI73A, GO73J, GR73C, GR73M, HA73F, HA73Q, HE73N, HO73N, KE73A, KO73J, KO73M, KR73F, LA73T, MA73W, MA73FF, ME73N, MI73M, NG73, NG73A, PA73G, RA73H, SE73H, SE73I, SU73B, SV73, UL73C, UN73, VA73, VA73K, AB74, AR74C, AY74A, CO74N, GO74I, HA74K, MA74V, MP74, NG74, RE74, SC74F, TI74A, TI74B, WO74C, ZU74, BA75I, GI75, HE75E, MA75B, MA75EE, MI75A, MU75C, SO75, CH76T, HA76E, MA76B, SA76J, SM76A, ST76D, UL76, FL77D, HE77D, PA77A, SH77C, SH77I).
Ground-state properties: (RU71F, SH71I, AB72E, AS72A, BR72O, CA72P, GR72K, GR72O, KR72A, KR72C, LE72Q, NI72E, OL72A, SC72O, YO72C, AR73R, CA73C, CU73, ER73D, FO73I, GO73J, GR73M, HO73V, KO73J, LE73M, MA73W, MC73B, ME73N, NG73, PA73G, PU73A, RE73E, SC73J, SV73, UN73, VA73, AB74, AR74C, CO74N, DE74T, EN74A, KH74B, KR74C, MA74F, MC74G, MP74, RE74, RI74B, SC74M, SH74K, TI74A, AL75G, BU75A, HO75M, LE75B, MA75K, MI75A, MP75, CH76D, FU76H, KE76, PO76, ST76D, AN77B, AN77F, KN77E, MP77, PA77A, SU77J, TH77A).
B(E2)(↑)[0 → 1.63] = 0.032 ± 0.003 e2 · b2 (SC77H);
= 0.037 ± 0.003 e2 · b2 (OL74);
= 0.028 ± 0.004 e2 · b2 (SI73K);
|M|2 = 23.0 ± 1.9 W.u. (OL74).
The total reaction cross section has been measured for E(10B) = 3.7 to 7.3 MeV (HI76C), and the elastic excitation function has been studied for 8 to 30 MeV (DI75F). Excitation functions for reactions (a) and (b) have been measured for Ec.m. = 3 to 10 MeV: large resonant structures are observed in most channels of reaction (b) (MA77AA): see (EN78). See also 10B in (79AJ01).
At E(14N) = 25 and 35 MeV angular distributions of the α-particles to 20Ne*(0, 1.63, 4.25, 4.97, 5.62, 5.78, 7.00, 7.17, 7.42, 7.83, 8.45, 8.78, 9.03 + 9.12, 9.99, 10.26, 10.61) have been measured by (MA74R, LE75J). The average behavior of the cross section is generally well described by a statistical mechanism but the reaction mechanism is not purely statistical (LE75J). For excitation functions see (VO72A, LE75J, MA77N, MA77V): see also (EN78). See also (ST73S) and (KL75A; theor.).
At E(16O) = 19.5, 24.3, 31.5, 35.9 and 42 MeV angular distributions have been measured for the 6Li ions corresponding to transitions to 20Ne*(0, 1.63, 4.25, 4.97, 5.62 + 5.78, 6.7 - 7.2). Hauser-Feshbach calculations are generally in good agreement with the data (LO76A). Differential cross sections at 7° have been measured at E(16O) = 45.6 MeV for many states of 20Ne with Ex < 10.62 MeV (FO74A). For fusion cross sections see (MO77G). See also (ST74H, EN78).
This reaction has been studied at E(16O) = 60 MeV (SC72C) and at E(11B) = 114 MeV (ST73Q): a number of states of 20Ne are populated but they are not excited strongly at either energy. See also (SC73K).
At E(9Be) = 16, 20 and 24 MeV, angular distributions have been measured for 20Ne*(7.4, 9.3, 11.0, 12.2) (EL77A).
At E(12C) = 45 MeV the population of states of 20Ne with Ex = 8.46, 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 states in italics 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 (KL74, KL76A). See also (MI73, ME74, HI77), (BR73N, FO73D, FO73J, FO74J, KL77B), (KL75A, KL75D; theor.) and 22Na in (EN78). For reaction (b) see (HI77).
Particle group and γ-ray energy measurements have been made for many states of 20Ne: see Table 20.21 (in PDF or PS). Angular correlation and γ-ray branching measurements [see Table 20.19 (in PDF or PS)] lead to the Jπ assignments shown in Table 20.21 (in PDF or PS), which also show level assignments to rotational bands. Angular distributions have been reported at E(12C) = 5.6 to 28.3 MeV [see (72AJ02)] and at E(12C) = 4.9 to 9.8 MeV (MA73M: α1 → α3, α4+5, α6, α7), 8.5 to 12.5 MeV (GA77A, GA77C: α0, α3), 13 to 22 MeV (ER76A, ER77C: α0 → α3, α6), 13 to 24 MeV (VO77A: α0 → α11), 15 MeV (BA76AA: α to 20Ne states with Ex < 8 MeV), 36.6, 36.8 and 37.4 MeV (FO76E: α0), 37 MeV (EB76: α0), 37 MeV (ME75A: see Table 20.21 (in PDF or PS)), 37, 41, 45, 48 and 51 MeV (GR75G: α to 20Ne*(7.42, 7.83, 9.04)), 38 MeV (FO76I: α0, α6), 45 MeV (GR75G: α to many states of 20Ne with Ex < 13.4 MeV) and 50 MeV (PA77B: α-particles to 20Ne*(0, 1.63, 4.25, 5.62, 5.78, 7.42, 7.83, 8.45). Both compound nucleus and direct reaction mechanisms appear to contribute to this reaction in the range E(12C) = 36 to 51 MeV. Strong fluctuations in the yield require the presence of narrow compound nuclear levels while the selective population of particular states indicates the presence of a strong direct component. Hauser-Feshbach theory predicts lower cross sections for low-J states than are experimentally observed (GR75G).
Studies of yields of particular α-groups are also reported for E(12C) = 8 to 16 MeV (GA77A, GA77C: α0, α3), 11 to 13 MeV (VO73C, VO74D: α to 20Ne*(6.72, 7.2)), 11.6 to 16 MeV (ER77C: α1, α6), 13 to 24 MeV (VO77A: α0 → α6, α11) and 25 to 27.1 MeV (CO72L: α0 → α3, α11); only the yields of α1, α2, α6 and α11 show strong fluctuations above E(12C) = 20 MeV.
The yields of α-particle groups corresponding to 20Ne states with Ex < 17.5 MeV have been studied in the range E(12C) = 32 to 51 MeV by (FO74F, GR74E, SH74B, GR75G, FO77, PA77B). Many strong structures are observed which are interpreted in terms of states in the compound nucleus, 24Mg: see (EN78). See also (BA76J, BA76AA, EB76, ER76A, FO76E, FO76I, ER77A, HI77C, KE77, MA77H, VA77A).
See also (FI72D, CO73Q, FE73A, KL74B, NA76G, ER77A), (BR73N, FO73D, FO73J, GO73T, SC73Y, ST73S, FO74H, FO74J), (AR73J, MA73M, TR73J, FO75B, DA77B; astrophys. considerations) and (SC73R, SI76H, DE77K, MA77W; theor.).
Angular distributions of the 6Li ions to 20Ne*(0, 1.63, 4.25, 4.97, 5.62 + 5.78, 6.7 - 7.2) have been measured at E(14N) = 30 and 36 MeV (LO76A), 52 and 60 MeV (MA71I), 52 and 78 MeV (HA74L: additionally 20Ne*(8.45 - 9.03)), and at E(14N) = 76.1 MeV and E(12C) = 67.2 MeV (BE73H: not 20Ne*(4.97) but additionally 20Ne*(8.45 - 9.03, 10.26 - 11.02, 11.95 + 12.13, 13.33, 13.92, 16.67, 17.38)). The angular distributions are symmetric about 90° and compound nucleus formation appears to be dominant (BE73H, HA74L). In the work of (BE73H) states which are particularly strongly populated are 20Ne*(16.67, 17.38, 18.11, 19.16, 19.6). The excitation functions for many states of 20Ne with Ex < 10 MeV have been measured by (VO75) for E(14N) = 20 to 60 MeV and by (MO77G) for E(14N) = 30 to 90 MeV. In addition, see (ST76C) and 26Al in (EN78). See also (ZE75), (BA71RR, BR73N, FO73D, SC73K, SC73Y, ST74H) and (KL74F, KL75A, KL75D, KL76A; theor.).
At E(18O) = 80 MeV, the population of 20Ne*(0, 1.63, 4.25, 4.97, 8.78, 11.95) is observed (BA74C).
Yield curves have been measured for E(6Li) = 4.1 to 6.3 MeV for the protons to 19F*(2.78) and for the d0 and α0 groups (RI68M) and at 5 to 9.2 MeV for the p0, p1, d0, d1+2, α0, α1+2 and α3+4 groups (LE77B): no structure is apparent.
Observed resonances in the yield of capture γ-rays over the range Eα = 0.8 to 10 MeV are displayed in Table 20.22 (in PDF or PS). Information on the character of the radiative decay is shown in Table 20.19 (in PDF or PS). For τm, see Table 20.20 (in PDF or PS).
The Jπ = 5- state at Ex = 8.45 MeV [Eα = 4.65 MeV] decays by an E2 transition [|M|2 = 26 ± 6 W.u.] to the 3- state at Ex = 5.62 MeV (RO71O). The Jπ = 6+ state at Ex = 8.78 MeV [Eα = 5.06 MeV] decays by an E2 transition [|M|2 = 20.4 ± 2.4 W.u.] to the 4+ state at Ex = 4.25 MeV (DI71, RO71F). See also (RO71R). The Jπ = 8+ state at Ex = 11.95 MeV decays by an E2 transition to the Ex = 8.78 MeV [Jπ = 6+] state which then decays via the 4+ and 2+ members of the ground-state rotational band. The transition probability of the 8+ → 6+ transition is 7.5 ± 2.5 W.u. which establishes 20Ne*(11.95) as the 8+ member of the ground-state band. The experimental E2 transition probabilities in the ground-state band deviate strongly from those predicted by the pure rotational model but agree reasonably well with simple shell-model predictions (AL72C). The T = 0 isospin impurity of 20Ne*(10.27) [2+; 1] is quite large: see (FI77E) for a discussion of this point and for CVC predictions of the weak magnetism form factors from the radiative widths for the transitions to 20Ne*(1.63, 7.42) [see Table 20.19 (in PDF or PS)]. See also (WA77H), (AL73E, HA74W) and (GA73H; theor.).
Excitation functions have been measured over a wide energy range for elastically and inelastically scattered α-particles, and γ-rays from the decay of 16O*(6.13, 6.92, 7.12): see Table 20.20 (in PDF or PS) in (72AJ02) for the earlier work and (HA73KK: 4.6 MeV and 14.1 to 17.1 MeV; α0, α1+2; the latter in the higher energy range), (ST77I: 6.9 to 10.2 MeV; α0, α2γ), (MA77C: 9.2 to 9.7 MeV; γ6.13), (CE75A: 12.8 to 14.8 MeV; α0), (BI75F: 14.0 to 18.1 MeV; α0, α1+2, α3, α4) and (BU72U: 22.75 to 28.40 MeV). See also (BE74L) and 16O in (77AJ02).
A number of anomalies are observed: they are displayed in Table 20.23 (in PDF or PS). Identifying various of the observed states as members of different rotational bands is discussed by (HA72K, HA73KK). The reduced α-widths in the first Kπ = 0+, 2- and 0- bands are small, indicating that the bands could be described in terms of the spherical shell model. The reduced widths within bands are found to decrease sharply with increasing spin (HA72K, HA73KK).
For reaction (b) see (72AJ02). For spallation reactions involving the emission of 6Li, 7Li, 7Be, 8Be and 9Be ions see (RU72A, JE74, RA74C). See also (AL73E) and (HO72G, HO72P, SU72B, AR73R, EB73, HO73W, IC73, CA74E, FR74C, KA74F, TA74C, WA74D, BA75A, CU75, KO75B, KU75G, MA75K, NE75B, TA75F, CU76F, HE76J, JA76C, LE76K, PA76D, AB77, AN77C, BA77L, FL77B, IK77, OH77C; theor.).
Deuteron groups have been observed to many states of 20Ne: see Table 20.24 (in PDF or PS). Angular distributions have been measured at a number of energies for E(6Li) = 5.5 to 25.8 MeV [see (72AJ02)] and at 32 MeV (GO73M, GO73N; abstracts; to most states shown in Table 20.24 (in PDF or PS) with Ex < 12.2 MeV), (GU77: d to 20Ne*(0, 1.63, 4.25, 4.97, 5.62, 7.00)) and at 35.3 to 45 MeV (AR75M, AR75O, AR76H: see Table 20.24 (in PDF or PS)). (GU77) report that the forward peaks of the deuterons to 20Ne*(4.97, 5.62) [Jπ = 2- and 4-] cannot be explained solely in terms of zero-range coupled-channel Born approximation α-transfer. The α-particle spectroscopic strengths for the ground state Kπ = 0+ states have been studied by (FO73C, AN75J). (FO73C) find 0.22 and 0.15 for the α reduced widths for 20Ne*(8.78, 11.95) in agreement with their assignments as the 6+ and 8+ members of the Kπ = 0+1 band. See also (PA72E, BE77K). (dγ) coincidences are being studied by (SU77I; abstract).
A number of 20Ne states have been studied in this reaction: see Table 20.24 (in PDF or PS) (CO76C) and P.D. Parker, private communication. Angular distributions have been reported at E(7Li) = 15 to 30.3 MeV [see (72AJ02)] and at 38 MeV (CO76C). Correlations between the tritons and the α-particles to 16O have been studied for a number of states of 20Ne at E(7Li) = 20 and 24 MeV: it is suggested that the reaction mechanism is mainly direct (PA74G). See also (SI77C). See also (BA72P, CA72A, PA72E, ST73F, SA77C), (BA71RR, GA72P, BR73N, FO73J, OG73, GO75Y) and (KU72D, KU72E, AR73R, IC73, MC73G, DO74L, NE74F, BI75H; theor.).
In reaction (a) at E(16O) = 58.3 MeV, 20Ne*(0, 1.63, 4.25 + 4.97) are strongly populated (WI74D). See also 24Mg in (EN78). For fusion studies see (KO76J, SW76F, WE76I, CH77F) and for other yield measurements see (EY76, SW77A) and 28Si in (EN78). See also (SC75D).
Angular distributions in reaction (b) have been studied at E(16O) = 27.1 to 37.1 MeV (HU77A; g.s.), 30.2, 30.7, 31.2 and 32.1 MeV (VI76A, BR77N; g.s.) and 46.4 MeV (JA76O; g.s.), at E(12C) = 56 MeV (MA76C: to 20Ne*(0, 1.63, 4.25, 5.8, 7.2, 8.8, 10.34, ~ 12)) and at 78 MeV (SA77, SA77C, SA77D, SA77J). At E(12C) = 56 MeV the strongest groups are those to the 6+ and 5- states 20Ne*(8.78, 10.26) (MA76C). See also (WO72A). At E(12C) = 78 MeV, 8Be - α correlations have led to a number of Jπ determinations and to measurements of Γα0/Γ: see Table 20.24 (in PDF or PS) (P.D. Parker, private communication). For yield measurements see (JA76O, VI76A, BR77N, FL77E, HU77A) and 28Si in (EN78). See also (PA72F, ME74B) and (YO73F, KR74J, BA75M, BU76L; theor.).
At E(13C) = 105 MeV the cross sections for formation of the Kπ = 0+ states 20Ne*(0, 1.63, 4.25, 8.78, 11.95) are in excellent agreement with shell-model predictions. 20Ne*(10.26, 17.38, 21.1), as well as the 4+, 6+ and 8+ states above, are strongly populated (PI76H).
At E(14N) = 155 MeV states with high angular momentum appear to be preferentially excited (NA76O).
Angular distributions have been reported at E(16O) = 23.9 MeV (SP74; g.s.), 44.3 - 54.5 MeV (SI72C, SI73; to 20Ne*(0, 1.63, 4.25)), 51.5 MeV (RO74B; to 20Ne*(0, 1.63, 4.3, 5.6 - 6.1, 8.5 - 8.9)) and 95.2 MeV (MO77H; to 20Ne*(0, 1.63)). At 55.5 MeV (ER73F, ER74; prelim.), 20Ne*(0, 1.63, 4.25, 4.97, 7.00) are populated. For yield measurements see (SI72C, PE73G, ER74, RO74B, SP74, KO77J) and 32S in (EN78). In particular the fusion cross section shows evidence of periodic structure between Ec.m. = 14 and 28 MeV, as predicted by the optical model (KO77J): a resonance (Γ ≤ 1 MeV) at Ec.m. = 26.5 MeV is suggested to be an α-exchange resonance. Polarization measurements are reported by (PO77). See also (ST73H, ST73S) and (AR72D, AR73K; theor.).
Angular distributions are reported at E(18O) = 28 and 32 MeV (BA71JJ).
At E(19F) = 36 MeV (GA73J) and E(16O) = 46, 58 and 68 MeV (PO75) angular distributions involving 20Ne*(0, 1.63) are reported. (PO75) have also studied 20Ne*(4.25): the strong population of the 4+ state may indicate evidence for a two-step process. See also (LO76C; theor.).
For reaction (a) see 19Ne. The ground state excitation energy for reaction (b) has been measured for E(3He) = 7.0 to 10.0 MeV: it shows a resonance corresponding to 20Ne*(28.). This resonance is also observed in the 16O(α, α) elastic scattering. It is interpreted in terms of a quasi-molecular α-particle cluster model (CO69S).
Angular distributions have been measured at Eα = 9.8 to 12.3 MeV by (HA67K: n1, n2, n4+5). The neutron decay of the lowest T = 3/2 state in 21Ne to 20Ne*(1.63) has been studied by (MC76J). The total neutron yield has been measured for Eα = 1.0 to 5.3 MeV by (BA73E). The astrophysical import of this reaction is discussed by (CL73C, FO75B). See also 21Ne in (EN78).
Neutron groups have been observed to a number of 20Ne states: see Table 20.25 (in PDF or PS) (AD69, GU70I, EV77). Angular distributions have been measured at E(3He) = 2.8 to 7.3 MeV (see (72AJ02)) and at 18 (EV77) and 18.3 MeV (PE75A).
At E(12C) = 46 MeV angular distributions to 20Ne*(0, 1.63, 4.25) have been studied: the 2p spectroscopic factors are 0.58, 0.24 and 0.20, respectively (CO75M).
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 displayed 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 (SE67B). See also (AV73).
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 (KU67I). 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 (KU72H). (MA76A) have determined the upper limits to the strengths of the transitions to various states of 20Ne from the 0+ and 2+ T = 2 states: these are displayed in Table 20.19 (in PDF or PS). No evidence is found for an isotensor transition amplitude (MA76A).
The elastic scattering has been studied in the range Ep = 500 to 2000 keV by (DE54D, PE54B, BA55A, WE55, DE56C, BE63G). Parameters for the observed resonances are exhibited in Tables 20.27 (in PDF or PS) and 20.28 (in PDF or PS) taken mainly form (BA55A). Some unresolved structure is observed at Ep = 900, 1092 and 1137 keV, in addition to a broad structure near Ep = 1700 keV (WE55). A sharp anomaly is observed in the elastic scattering at Ep = 4.096 ± 0.003 MeV (BL67F), 4.090 ± 0.005 MeV (KU67I). It is an s-wave resonance corresponding to the 0+; T = 2 state at Ex=16.73 MeV (BL67F, KU67I). There is no indication of this resonance in the p3, p4 or p5 yields (KU67I). The amplitude of the T = 1 or T = 0 impurity in this state is ~ 1.5% (BL67F). In the range Ep = 5.65 to 6.21 MeV, a single anomaly is seen in the elastic scattering at Ep = 5.879 ± 0.007 MeV. The interference patterns show that the scattering is d-wave, corresponding to the excitation of the 2+; T = 2 state at Ex = 18.43 MeV (KU72H). The 5.88 MeV anomaly also appears in the p1, p3, p4 and p5 yields (KU72H). The parameters of these two T = 2 states are shown in Table 20.27 (in PDF or PS). The elastic scattering has also been studied for Ep = 4.2 to 7.5 MeV by (TH67J). The total reaction cross section is reported for Ep = 24.9 to 46.3 MeV by (MC74F: 8 energies in that range).
Resonances for inelastic scattering involving 19F*(0.11) (Jπ = 1/2-) and 19F*(0.197) (Jπ = 5/2+) [p1 and p2] are listed in Table 20.29 (in PDF or PS) (BA55, BE63G). In general the resonances observed are identical with those reported from other 19F + p reactions, although the relative intensities differ greatly. The p2 scattering has been measured at Ep = 5.6 to 6.3 MeV (TH67J), and at Ep = 3.5 to 7.0 MeV the yields of p2, p3, p4 and p5 show structures (BE73T; prelim.). The analyzing power has been measured for the p0, p2 and p5 groups with polarized protons in the range 4 to 10 MeV: strong structures are observed for p0 (EN75, EN76B; prelim. work; and R. Kaita, private communication). See also (72AJ02, HA74Q) and 19F.
Yield measurements have been reported for Ep = 4.23 to 11 MeV: see (72AJ02) and (KU72H: 5.78 to 5.96 MeV; σt, n0, n1+2). Observed resonances are displayed in Table 20.30 (in PDF or PS). A narrow anomaly is reported in the n0 and n1+2 yields at Ep = 5.879 ± 0.007 MeV, corresponding to the 2+; T = 2 state of 20Ne at 18.43 MeV (KU72H). See also 19Ne.
Many resonances occur in this reaction. They are displayed in Tables 20.31 (in PDF or PS), 20.32 (in PDF or PS) and 20.33 (in PDF or PS) depending on whether they are observed in the α0 yield [Table 20.31 (in PDF or PS)], in the α1 [or απ] yield to 16O*(6.05) [Table 20.32 (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 20.33 (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 discussed below.
A listing of the earlier yield studies is given in (72AJ02). A detailed discussion of the evidence leading to many of the Jπ assignments shown in Table 20.33 (in PDF or PS) is given in (59AJ76). Recent measurements are reported by (CA74L: Ep = 0.6 to 1.8 MeV; α0 → α4), (HE72E: 1.3 to 2.2 MeV; γ6.13, γ6.92, γ7.12) and (KU72H: 5.65 to 6.20 MeV; α0 → α5, α7 → α9). The width of the forbidden decay of the 1+ state at 13.17 MeV [see Table 20.33 (in PDF or PS)] by α0, Γγ0 < / ~ 7 x 10-6 eV (KR74I; prelim. results). Anomalies are observed in α0, α1, α2, α4 and α8 but not in α3, α5, α7 and α9 corresponding to the formation of the 2+; T = 2 state at 18.43 MeV [Ep = 5.88 MeV] (KU72H). The analyzing power for α0, α1+2, α3 and α4 have been measured for Ep = 4 to 10 MeV: strong structures are observed (EN75, EN76B; prelim. results; and R. Kaita, private communication). See also (HA74Q, LO74F, CA76S), (GA76B; theor.), (CL77C; astrophys.) and 16O in (77AJ02).
The excitation curves show strong resonant behavior (cross sections up to 1.5 mb/sr) for Ex = 15.3 to 18.7 MeV, over which region 28 angular distributions have been measured. Twelve states with Jπ ≤ 4+ have been observed. The strongly populated states are in better agreement with those reported in the (p, α1) yield to 16O*(6.05) [Jπ = 0+] than those reported in the (p, α0) yield (GO69I, GO71S). It is suggested that most of the observed states are of 8p - 4h and 12p - 8h configurations (GO71S). [(GO69I, GO71S) are preliminary reports.]
Levels of 20Ne derived from reported neutron groups are displayed in Table 20.34 (in PDF or PS). Angular distributions have been measured at Ed = 0.5 to 6.1 MeV: see (72AJ02) and at Ed-bar = 8 MeV (BE76R: n1, n6). The branching ratio for the γ-decay of the lowest 1+; T = 1 state [20Ne*(11.23)] to the ground state to 20Ne*(1.63) is 0.53 ± 0.07 (KU73B: Ed = 5.5 MeV). See also (LE75C; applied) and (72AJ02).
Levels of 20Ne observed in this reaction are displayed in Table 20.35 (in PDF or PS). Deuteron angular distributions have been measured at E(3He) = 9.5 and 10.0 MeV (SI65D), 13.0 MeV (JA63), 16 MeV (VE74C, SE76I), 18 MeV (BE75A, FO76C) and 21 MeV (OB73). Spectroscopic factors obtained by (OB73, BE75A, FO76C, SE76I) are shown in Table 20.35 (in PDF or PS). The angular distribution of the deuterons to 20Ne*(4.25) is explained in terms of inelastic effects (VE74C). See also (SI65D) and (SU77J; theor.).
At Eα = 28.5 MeV angular distributions are reported for the tritons to 20Ne*(0, 1.63, 4.25, 4.97, 5.62 + 5.78, 7.00 + 7.17 + 7.19) (HA67O; DWBA). The distributions of the tritons to 20Ne*(0, 1.63, 4.25) [Jπ = 0+, 2+ and 4+, respectively] have been reanalyzed in terms of the collective-model coupled-channels Born-approximation theory: C2S for these three states are 0.08, 0.16 and 0.0 (CCBA) [the DWBA results are nearly the same]. Agreement with the values obtained in the (d, n) and (3He, d) reactions is poor (OB74). Angular distributions have also been reported at Eα = 18.5 and 28.4 MeV: see (72AJ02).
Angular distributions have been studied at E(7Li) = 34 MeV for the transitions to 20Ne*(0, 1.63, 4.25, 4.97 (partial), 5.62, 5.78, 6.72, 7.1, 7.42). The spectroscopic factors, C2S, for 20Ne*(0, 1.63, 4.25, 5.78, 6.72, 7.42) are 0.36, 0.54, 0.06, 0.20 and 0.22, respectively, in good agreement with those reported in the (d, n) and (3He, d) reactions (WI75F).
The decay is principally to 20Ne*(1.63) with a half-life of 11.00 ± 0.02 sec: see reaction 1 in 20F and Table 20.36 (in PDF or PS) for the branching to various 20Ne states. The 0.02% branching to 20Ne*(4.97) [Jπ = 2-] is consistent with the assignment Jπ = 2+ to the ground state of 20F (GA69E), as are measurements of the β - γ circularly polarized correlation (FR61A, MA65B). When the β - γ correlation is described by W(θ) = 1 + pcos2θ, p has a value slightly different from zero and it varies linearly with E: dp/dE = +0.09 ± 0.05% MeV-1 (MC77A). (TR77E) report dp/dE = +0.05 ± 0.07% MeV-1 and (RO77N) find +0.02 ± 0.02 MeV-1. The β-decay asymmetry, (ft)+/(ft)- = 1.044 ± 0.010 (AL75I), 1.025 ± 0.013 (GE76B): see also reaction 58 and (ST74I). (RO77N) find, by comparison with 20Na, a vanishing second class current: the ratio of the second-class axial matrix element to the main first-class one is 1.1 ± 1.5 and a first-class second-forbidden axial contribution is 40 ± 8.
The energy of the γ-ray from 20Ne*(1.63) is 1634.8 ± 0.6 keV (VA67E), 1632.6 ± 0.8 keV (AL66C), 1633.7 ± 0.3 keV (SP68), 1633.6 ± 0.3 keV (OP72). The γ-ray from the (4.97 → 1.63) transition has Eγ = 3334.3 ± 0.7 keV, ΔEx = 3334.6 ± 0.7 keV, and using the Ex for 20Ne*(1.63) shown in Table 20.18 (in PDF or PS), Ex for 20Ne*(4.97) = 4968.4 ± 0.8 keV (GA69E).
Bremsstrahlung measurements show peaks in the neutron yield (reaction (a)) at 17.8, 18.8, 19.1, 20.1, (22.0), (23.0) and (24.8) MeV [numbers in parentheses refer to relatively weak and broad structures]. The giant dipole resonance is centered at ~ 20 MeV and the integral cross section to 28 MeV exhausts half of the dipole sum rule (WO75). The cross section for (γ, Tn) using monoenergetic photons shows a structure at 18 MeV and some fluctuations atop the broad giant dipole resonance, σmax ~ 7 mb. The double photoneutron cross section, σ(γ, 2n), is dominated by a single peak at ~ 20.5 MeV, σmax ~ 1.1 mb (VE74D). See also (72AJ02, BR75H, WO75, DA77E) and (RO73W, SC75E; theor.). For reaction (c) see (DO62B, FI63D, HO69Q) and (SC75Z; theor.). For reaction (d) see (HA59K) and reaction 47.
Form factors for many of the excited states of 20Ne with Ex < 8 MeV have been reported: see (SI73K; Ee = 77.0, 81.3, 102.4, 110.5, 114.4 MeV) and (MI72E; 200 and 250 MeV). The monopole matrix elements for the 0+ → 0+ transitions are 7.4 ± 2.0 and 6.9 ± 1.4 fm2 for 20Ne*(6.72, 7.19) (MI72E) while (SI73K) calculate Γπ = 3.9 x 10-5 eV for 20Ne*(6.72). B(E2)(↑) is 0.028 ± 0.004 e2 · b2 for the transition to 20Ne*(1.63). The transitions to 20Ne*(4.25, 7.83) correspond to 23 ± 5 W.u. and 0.77 ± 0.25 W.u. (SI73K). (MI72E) report B(E2)(↑) = 0.13 ± 0.03 and 0.83 ± 0.13 W.u. for the transitions to 20Ne*(7.42, 7.83).
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 at an Ex = 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 ((BE71N), and W.L. Bendel, private communication). See also (CH75U, SZ75).
A study of reaction (b) at Ee = 30 MeV shows strong resonances (assuming ground-state transitions) at Ex = 17.70, 18.87, 19.87 and 21.02 MeV, respectively, as well as some weaker structures (DO62B).
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 (SK75A).
Angular distributions of elastically scattered protons and of a number of inelastic groups have been measured for Ep = 2.15 to 41.8 MeV: see (72AJ02) for the earlier work and (MA69AA: 3.66 to 5.90 MeV; p0, p1), (SW76, SW76E: 24.5 MeV; p to 20Ne*(0, 1.63, 4.25, 4.97, 5.62, 5.78, 6.72, 7.00, 7.17 + 7.19, 7.42, 7.83, 8.45, 8.69, 8.78, 9.03, 9.12, 9.31 + 0.02, 9.51)), (DE73L, DE74Q: 30 MeV; p0, p1, p2) and (CO77N: 35.2 MeV; p0). The Ep = 24.5 and 30 MeV angular distributions for the 0+, 2+ and 4+ members of the ground-state Kπ = 0+ band are well fitted using coupled-channels calculations and deformation parameters of β2 = +0.47 ± 0.04 and β4 = +0.28 ± 0.05. When the 6+ state is included [20Ne*(8.78)], the fit is improved if β6 = -0.10 is included (DE73L, DE74Q, SW76, SW76E). The state at Ex = 9.31 ± 0.02 MeV is suggested to have Jπ = (4+) and to be the 4+ member of the Kπ = 0+ band based on 20Ne*(6.72): β2 = 0.15 (SW76E): see, however, Table 20.35 (in PDF or PS).
For p - γ angular correlations see (72AJ02). See also (MA69AA). For polarization measurements see (DE72F, SW76, PL77B) and 21Na in (EN78). For yield measurements see (HI72B, SW76E) and 21Na in (EN78). For reaction (b) see (EP71B). See also (QU70C). For a study of spallation see (PA74C). See also (AS72A, AM76A, ES76; theor.). For reaction (c) see (KA64D; theor.).
Angular distributions have been reported at Ed = 10.95 to 11.8 MeV and at 52 MeV [see (72AJ02)], at Ed-bar = 10.0 to 12.0 MeV (DA75C; d1), 11.6 MeV (BR73H; d0) and 11.66 MeV (DA75C; d2) and at Ed = 40 MeV (EP74A; d1 and d2). See 22Na in (EN78) for polarization and yield measurements. See also (SI71G; theor.).
Angular distributions have been measured at E(3He) = 10 to 35 MeV [see (72AJ02)] and at 68 MeV (DE74G: 3He to 20Ne*(0, 1.63, 4.25)). The angular distributions at E(3He) = 68 MeV are well fitted by a coupled channels calculation with β2 = 0.47 and β4 = 0.17 (DE74G). See also (MA75P, MA76U; theor.).
Angular distributions have been measured to low-lying states of 20Ne at Eα = 3.8 to 155 MeV: see (72AJ02) and (AB75C, DA75B: α0; 3.8 to 8 MeV), (EN77: α0; 20.2 - 23.0 MeV), (CO75C: α0; 26.6, 27.2 and 27.8 MeV), (RE72D: α0, α1, α2; 104 MeV) and (KN76E: α1 and α to 20Ne*(18.1 - 28.2); 155 MeV). A coupled-channel analysis of the work at Eα = 104 MeV leads to β2 = +0.35 ± 0.01, β4 = +0.11 ± 0.01, Q20 = +0.46 ± 0.02 b and Q40 = +0.026 ± 0.002 b2 (RE72D). At Eα = 155 MeV (KN76E) find that the strength concentrated in the giant quadrupole resonance exhausts more than 30% of the isoscalar energy weighted sum rule. See also (MO75, YO76C). Yield measurements are reported by (BA74W: Eα = 10.25 to 14.82 MeV; most α-groups to 20Ne* states with Ex < 8 MeV) and by (AB75C, CO75C, CO75Q, DA75B). See also (HA74W, HA76T) and (FE71E, MA72T, RE72C, SH72B, RE73E, FE74, MA74F, GI75C, BE76BB, MA76J, MA76U, KN77E; theor.).
The elastic angular distribution has been measured at E(7Li) = 36 MeV (CO76C).
Elastic angular distributions have been obtained at E(12C) = 22.2, 27.2, 32.3, 37.3 and 42.7 MeV [see (VA74E)] and at E(20Ne) = 65.7 MeV (DO75D). For a fusion study, see (CO77P). See also (PR77C) and (VA76G, OS77A; theor.).
Angular distributions have been studied at E(20Ne) = 50 MeV (ST76I) and 94.8 MeV (MO77H) involving 16Og.s. and 20Ne*(0, 1.63, 4.25): qualitative agreement is found with the assumption of an α-cluster exchange process dominating at backward angles (ST76I). See also (ZI75A).
The static quadrupole moment of 20Ne*(1.63), Q20 = +0.94 ± 0.38 b (SC69D).
20Na has a half-life of 446 ± 3 msec: see reaction 1 in 20Na. It decays to a number of states of 20Ne, principally 20Ne*(1.63): see Table 20.37 (in PDF or PS). The ratio of the mirror decays 20Na β+/→ 20Ne*(1.63) and 20F β-/→ 20Ne*(1.63), (ft)+/(ft)- = 1.026 ± 0.024 (TO73C), 1.033 ± 0.022 (IN76C). (RO77S) obtain a correlation W+(θ) = 1+ cos2θ[(-4.0 ± 0.7) x 10-3E + (1.3 ± 0.9) x 10-4E2](p/E)2: assuming the validity of CVC this leads to a vanishing second-class current. See also reaction 45. The β - α angular correlation involving the allowed transition to 20Ne*(7.42) is consistent with the predictions of the CVC theory (FR77D). See also (TO72A, IN73, AL74, RO75A, RO77J) and (WI71P, EM72, WI72L, LA73, WI74, WI75D, CA77F, OK77C, WI77; theor.).
Angular distributions have been measured for the first four deuteron groups at Ep = 14.1 MeV (HE72C) and 20 MeV (HO70R). (HE72C) report spectroscopic factors of 0.50 and 0.14 for 20Ne*(1.63, 4.97): the other two distributions do not show direct reaction features.
The T = 1 states observed in this reaction, and the analog states observed in 20F in the (d, 3He) reaction, are displayed in Table 20.16 (in PDF or PS). The spectroscopic factors of analog states are consistent to within 20% for states excited by a single l-transfer. T = 0 states are displayed in Table 20.38 (in PDF or PS) (MI74J).
Angular distributions have been reported at Ep = 26.9, 35.1 and 42.4 MeV (FA71B: t0, t1, t2, t3, t4+5, t6) and at 43.7 MeV (CE64B). At the higher energy the distributions of the tritons to the ground state of 20Ne and to the first 0+; T = 2 state [Ex = 16.722 ± 0.025 MeV (HA69H)] have been fitted by L = 0 and the tritons to 20Ne*(18.5) by L = 2. The latter is the first 2+; T = 2 state (CE74B). 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 (MC70A). The ratios of the cross section for formation of the analog states 20Ne*(10.27)/20F*(0) and 20Ne*(12.25 ± 0.03)/20F*(1.85) are 2.00 ± 0.20 and 1.40 ± 0.15, respectively, at Ep = 45 MeV (HA69F). See also (GO71R).
At Ep = 40 MeV angular distributions of the tritons to 20Ne*(4.97, 5.62, 7.00) [Jπ = 2-, 3- and 4-, respectively] have been measured. Coupled-channels calculations reproduce the distributions to the 2- and 3- states, but the distribution to the 4- states cannot be explained entirely in terms of multistep inelastic processes (CH75M). See also (VO74E).
The first five states of 20Ne have been observed in this reaction, and angular distributions have been measured at Ep = 10.0 and 45.5 MeV: see (72AJ02).
At E(3He) = 40.7 MeV, angular distributions have been measured to 20Ne*(0, 1.63, 4.25) and analyzed using zero-range DWBA (OH72A).
For reaction (a) see (CL73C; astrophys.). For reaction (b) see (LI70G, ST75F). See also (BA75C), (RO75S) and (PA75D, CH77A; theor.). At Eα = 90 MeV 20Ne states at Ex = 0, 1.63 ± 0.035, 4.25 ± 0.06, 5.70 ± 0.06, 6.72 ± 0.05 and 11.41 ± 0.05 MeV are populated: the ground states Sα (DWIA) = 1.3 ± 0.2 (SH76A).
Angular distributions have been studied involving 20Ne*(0, 1.63, 4.25) at Ed = 28 MeV (CO72I), 35 MeV (CO76I; also 20Ne*(5.62, 5.78)), 54.3 MeV (TA77J; also 20Ne*(5.62 + 5.78)) and 80 MeV (DJ74; also 20Ne*(5.62)). Using zero-range DWBA, (CO76I) report Sα = 0.21, 0.19, 0.87, 0.26, 0.04 for 20Ne*(0, 1.63, 4.25, 5.62, 5.78). See also (FO73D, FO73J, FO74J).
Angular distributions involving 7Beg.s. and 7Be*0.43 and 20Ne*(0, 1.63, 4.25) have been measured at E(3He) = 25.5 MeV (PI76D) and 70 MeV (ST76H; also 20Ne*(4.97, 5.62)). Spectroscopic factors from a FRDWBA analysis of the 25.5 MeV data give 1.0, 15.4 and 3.5 [from 7Beg.s. data] and 1.0, 23.4 and 4.3 [from 7Be*0.43 data] for 20Ne*(0, 1.63, 4.25). The absolute spectroscopic factors for 20Neg.s. are 0.67 [7Beg.s.] and 0.63 [7Be*0.43] (PI76C, PI76D). See also (BR73N).