(See Energy Level Diagrams for 20Ne)
Electromagnetic transitions: (MC76M, MA77LL, GO78E, GR78B, HA78J, RO78K, SC78F, SI78A, TO78B, FU79D, FU79N, KA79N, SI79H, BR80E, KO80R, CO81H, KH81B, KN81B, MC81B, SC81H, HA82C, HA82D, HA82G, LA82, RI82B).
Special states: (BA77RR, FO77G, SC77M, SH77M, AL78R, GO78E, GR78B, HO78D, KA78I, MA78S, MC78D, PE78B, PI78B, PI78G, RA78I, RO78K, SC78F, SI78A, TA78U, TO78B, ZA78C, DA79M, FU79D, FU79N, IN79D, KA79N, KO79A, MI79J, SI79H, WI79N, BI80, BR80N, CA80D, FO80A, FU80I, KL80A, KO80Z, CO81H, ER81D, RA81M, SC81H, WI81B, WI81L, AO82A, KI82, MI82A).
Astrophysical questions: (AL77S, FR77G, BU78G, CL78G, DI78D, DW78A, ME78F, OR78, PO78B, TR78, WO78F, CH79I, DI79C, GA79I, LA79F, LE79M, MA79C, ME79C, RA79H, SI79B, BH80A, CO80S, FR80B, MO80N, SC80L, WI81C, AU81C, DU81C, SH81I, WE81I, WO81C).
Applied topics: (KU79K).
Complex reactions involving 20Ne: (CA78K, HE78J, KA78C, OB78A, SA78K, SH78M, VO78, WI78B, YO78A, AL79H, BE79W, CE79A, DA79L, GA79, GA79H, GO79J, HA79A, HE79I, KN79H, MC79D, MO79V, NA79L, SA79H, ST79M, SY79, TA79I, AK80B, CH80E, EV80, GR80D, NA80C, RA80J, CE81D, EG81B, GR81B, HI81B, LO81F, MA81G, NA81C, SC81, TA81, ME82A, SU82, TA82).
Pion and kaon capture and reactions: (BA77XX, NO77F, ST77V, YE77B, AN78I, AT78, BE78P, YU78, AK79, AL79E, BA79S, BE79W, HA79A, JA79F, KN79C, MI79C, NA79L, NA79N, SA79H, TA79I, TR79H, OT80, ST80G, TR80, AN81G, AS81, GY81A, MA81F, BI82B, MU82, OS82, RA82).
Other topics: (BO77R, GR77H, SA77W, SH77M, AN78D, FI78D, MA78S, MC78D, RA78K, RO78P, SA78A, TA78Q, BE79A, BO79W, BR79J, CH79G, CO79C, CO79D, EL79B, GO79T, HA79P, HA79V, HE79, KA79N, ST79R, WI79N, WU79A, BR80N, DI80B, KO80Z, RO80B, TE80, ZO80, AR81, CA81H, ER81D, IS82, KI82).
Ground state of 20Ne: (MC76M, BO77R, HA77W, MA77LL, ZA77C, AN78B, AR78A, CH78Z, FI78D, GO78E, HE78K, RO78P, SM78D, SV78, SW78, TA78Q, ZA78B, BO79W, BR79J, CH79G, HA79P, HA79V, IN79D, KA79N, MA79, SI79H, WU79A, BR80E, BR80I, DI80B, LE80T, MO80H, TE80, AR81, HA81Q, SC81H, DE82G).
Q4.25 = 0.022 ± 0.003 e2 · b2 (GR78B);
weighted mean = -0.01 ± 0.14 (SP82).
Excitation functions for reactions (a) and (b) have been measured for Ec.m. = 3 to 10 MeV: large resonant structures are observed in reaction (b). Particularly pronounced structures [~ 0.6 MeV] corresponding to Ex ~ 38 MeV (α0) and 38.6 MeV (α to 16O*(7.0, 10.3, 16.2 [u]) are reported (MA78A). The elastic excitation function has also been studied for E(10B) = 8 to 30 MeV by (DI75F). See also (78AJ03), 10B in (79AJ01) and 16O in (82AJ01).
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 (LE75J, MA74R). The average behavior of the cross section is generally well described by a statistical mechanism but the reaction mechanism is not purely statistical (LE75J). Angular distributions are also reported at E(14N) = 23.5 MeV (DU78B: α0, α1, α2, α4+5). For experiments relating to the compound nucleus see (78AJ03) and (MA77FF, DU78B, DU78J, WU78C, BA81Y). See also (KL76B, HO78N).
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). See also (MO77Y) and (78AJ03).
At E(11B) = 115 MeV, angular distributions are reported to 20Ne*(7.17, 8.78, 10.25, 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- (BR79B, RA79C). See also (78AJ03).
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). It is suggested that 20Ne*(7.3, 9.2, 12.2, 15.7) correspond to the 0+ + 2+, 4+, 6+ and 8+ members of the Kπ = 0+3 band (SU81).
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 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 (KL76A). At E(10B) = 20.0 and 20.5 MeV angular distributions are reported to the 2+ states 20Ne*(7.42, 7.83). 20Ne*(7.83) is more strongly populated than 20Ne*(7.42), and it, and 20Ne*(7.19), have integrated cross sections which deviate from the (2J + 1) "rule" by a factor of about two (FO78). See also (78AJ03) and (KL76B, HO78N).
Double and triple (α, α, γ) correlations and γ-ray branching measurements [see Table 20.18 (in PDF or PS)] lead to the Jπ assignments shown in Table 20.19 (in PDF or PS), which also shows level assignments to rotational bands. Angular distributions have been reported at E(12C) = 4.9 to 51 MeV [see (78AJ03)] and at E(12C) = 6.3 to 6.6 MeV (IS80A; α0, α1), 10 MeV (BE81GG; α0), 12 MeV (BE81GG; α1), 19.3 MeV (AN80; α0) and 33 to 40 MeV (FO82; α0). τm for 20Ne*(4.25) is 95 ± 13 fsec (SP82) [see also for g-value, the "Ground state of 20Ne" section here].
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 (78AJ03) for the earlier work and (CI77C, CO77U, PA77J, TR78E, DE79B, AN80, CO80B, ER80E, IS80A, KO80, BE81GG, FO82). See also (MA78GG), (SC78B, GO79W), (RO78B, RO78O, BE81GG, IB82; astrophys.) and (AB77E, BR78B, MA78II, TO78C, GA80F, NO81A, SU81D; 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. Compound nucleus formation appears to be dominant. In the latter work (BE73H) 20Ne*(16.67, 17.38, 18.11, 19.16, 19.6) are particularly strongly populated. For complete references see (78AJ03). See also (ST77Q) and (KL76B, HO78N).
Yield curves for E(6Li) = 4.1 to 9.2 MeV do not show any structure: see (78AJ03).
Observed resonances in the yield of capture γ-rays over the range Eα = 0.8 to 10 MeV are displayed in Table 20.20 (in PDF or PS). Information on the character of the radiative decay is shown in Table 20.18 (in PDF or PS). 20Ne*(11.261) [Jπ = 1+; T = 1] is not observed: Γα < 3 x 10-5 eV, leading to |< 1+VPNC1- >| < 1.2 eV (FI80B). 20Ne*(12.25) is the 3-; T = 1 analog of 20F*(1.97) (FI80). See also (78AJ03, NO79E), (IB82; astrophys.) and (DU82; theor.).
Excitation functions have been measured over a wide range for elastically and inelastically scattered α-particles, and γ-rays from the decay of 16O*(6.13, 6.92, 7.12): see (78AJ03) and (GA81O; 9.5 to 9.8 MeV; α1), (BI79; 14.6 to 20.4 MeV; α0 → α5), (AR79E; 17.5 to 22.7 MeV; α0) and (CO78I; 27 to 33.6 MeV; α0).
A number of anomalies are observed: they are displayed in Table 20.21 (in PDF or PS): see, in particular, (HA72K, HA73KK, BI79). (AR79E) report structures in the range Ex = 18.7 - 22.9 MeV which are similar to those observed in 16O(6Li, d)20Ne* → α + 16Og.s.. The excitation function for α0 at 178.1° shows a very strong structure at Eα ~ 29.5 MeV as does the excitation function for deuterons to 18F*(1.13) [Jπ = 5+] (CO78I, CO79O): this anomalous scattering is correlated with a large variation in the degree of forward peaking of the (α, d) process.
For reaction (b) see (80AJ01). For spallation reactions see (78AJ03) and (VI79, GO80C, RE80A, GO81B). See also (BE81Y), (RA79H; astrophys.), (ST77U, FI82) and (PA76I, BA77OO, BA77RR, IK77B, TO77L, FL78D, KA78I, NO78B, TA78U, TH78E, TO78B, AR79E, LE79A, LE79D, VE79C, VE79E, BA80KK, FL80C, FU80G, LE80T, TO80D, AO81B, FI81B, GY81, WI81B, AO82A, BI82C, FL82, LA82C; theor.).
Deuteron groups have been observed to many states of 20Ne: see Table 20.22 (in PDF or PS). Angular distributions have been measured for E(6Li) = 5.5 to 45 MeV [see (78AJ03)] and at 20 and 38 MeV (AN79; d0, d1, d2), 32 MeV (AN79; to all states shown in Table 20.23 (in PDF or PS) with Ex < 12.2 MeV, except 20Ne*(10.7)), 42 MeV (BE78U; d0, d1) and 75.4 MeV (TA81P, TA81F; d to 20Ne*(0, 1.63, 4.25, 5.78, 7.17, 8.78, 10.26, 11.95); Sα = 1.0, 0.96, 1.0, < 0.93, 0.49, 0.98, 0.88, 0.65, respectively; 20Ne*(12.59, 13.90, 15.34, 17.30) were also populated. Reaction processes are discussed by (AN79). See also reaction 14 (AR79E) and (ES79; d - γ involving 20Ne*(1.63, 4.25)). For excitation functions see (HO78). See also (MA80J), (ST77U, FU79R, AN80F) and (GY81, LE81G, MA81W, XE81, SE82B; theor.).
States observed in this reaction are displayed in Table 20.22 (in PDF or PS). Angular distributions are reported at E(7Li) = 15 to 38 MeV [see (78AJ03)] and at 50 and 68 MeV (BR79B; to 20Ne*(1.63, 4.25, 7.17, 8.78, 10.25, 15.4; see also for C2S). See also (78AJ03).
Angular distributions in reaction (a) have been measured for E(16O) = 27.1 to 46.4 MeV [see (78AJ03)] and 28.5 to 35.2 MeV (VI79A; g.s.), 43.2 to 53.0 MeV (JA79N; g.s.) and 43.9 MeV (EB79; g.s.), and at E(12C) = 56 MeV (MA76C), 22.7 to 32.4 MeV (HU80A; g.s.) and 78 MeV (SA79K; see Table 20.23 (in PDF or PS)). Γα0/Γ measurements derived from 8Be - α correlations are listed in Table 20.22 (in PDF or PS) (SA79K). For reaction (b) see (78AJ03). For yield and cross-section measurements see (BR77W, CH78L, DI78, KA78E, TA78E, EB79, FL79G, JA79N, KO79B, VI79A, HA80H, HU80A, SI80J). See also (GO79W, RA81K) and (SA81H; 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 (BR79B): the first four states are the 2+, 4+, 6+ and 8+ members of the 0+ 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*(12.56, 15.9, 17.3) [Jπ = 6+, 8+, 8+] (BR79B). See also (FO77G, 78AJ03).
Angular distributions have been reported at E(16O) = 23.9 to 51.5 MeV [see (78AJ03)] and at 35 MeV (KA77AA; 20Ne*(0, 1.63)), 68 and 90 MeV (PO77D, PO79F; 20Ne*(0, 1.63, 4.25, 7.16, 8.45, 8.78, 10.26, 11.95)) and 95.2 MeV (MO77Y, MO79Z; 20Ne*(0, 1.63)). (PO79F, PO81) report that 20Ne*(7.17, 8.45, 8.78) are strongly aligned and polarized along an axis perpendicular to the reaction plane. See also (PO77D) and (BO80I; theor.). For partial fusion excitation functions see (FE78B, TS78A, KO79M). See also (78AJ03, FI78A, GO79W, BR81L) and (KR81C, KO82; theor.).
For reaction (a) see 19Ne. The excitation function for α0 [E(3He) = 7.0 to 10.0 MeV] shows a resonance corresponding to 20Ne*(28.): see (78AJ03). Polarization measurements are reported at E(pol. 3He) = 33 MeV for the t0 group [reaction (b)], the 3He groups to 17O*(0, 0.87) [reaction (c)] and the α-groups to 16O*(12.97, 13.26) [reaction (d)] (BA81C, KA81D, LE81F). See also (RO81C).
At E = 115 MeV the 8+ state at Ex = 11.95 MeV is particularly strongly populated in both reactions. 20Ne*(1.63, 4.25, 7.16, 8.78, 10.3, 15.3, 15.9, 17.3, 21.1) are also observed (GO79R).
At E(11B) = 114 MeV, 20Ne*(4.25, 8.9, 10.39, 15.43) are relatively strongly populated: see (78AJ03).
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 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 (SE67B). 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 (CA80F).
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 20.18 (in PDF or PS). No evidence is found for an isotensor transition amplitude (MA76A). Resonances observed in this capture reaction are displayed in Table 20.24 (in PDF or PS). See also (HA79K) and (SC78F, SC80M; theor.).
Resonances for inelastic scattering [p1 and p2] are listed in Table 20.26 (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. For reduced widths see Table 20.28 (in PDF or PS) in (78AJ03). See also (KE81E; thick target yields; Ep = 1.75 to 2.75 MeV), (CU80D, FI82) and (PH77C; theor.).
Many resonances occur in this reaction. They are displayed in Tables 20.28 (in PDF or PS), 20.29 (in PDF or PS) and 20.30 (in PDF or PS) depending on whether they are observed in the α0 yield [Table 20.28 (in PDF or PS)], in the α1 [or απ] yield to 16O*(6.05) [Table 20.29 (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 20.30 (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 (72AJ02, 78AJ03). A detailed discussion of the evidence leading to many of the Jπ assignments is given in (59AJ76). For values of θ2 see Table 20.28 (in PDF or PS) in (78AJ03). Recent measurements are reported by (DE78I, CU80D; 0.70 to 2.68 MeV; α0, απ, α2, α3, α4), (DI80; 0.4 to 2.0 MeV; α0, αγ) and (ST77; 12.4 to 18.0 MeV; α0). In the latter work resonant structures with Γ ~ 0.5 to 1 MeV are reported at Ep = 13.0, 14.3, 15.3, 16.5, (17.5), corresponding to 20Ne*(25.2, 26.4, 27.4, 28.5, (29.5)) (ST77).
Longitudinally polarized protons with Epol. p ~ 0.67 MeV have been used to study 20Ne*(13.48) [Jπ = 1+; T = 1]: the maximum of the analyzing power was found to be (6.6 ± 2.4) x 10-3. The parity mixing of the 670 keV resonance appears to be caused by the T = 0 continuum as well as by the 1- state at Ex = 13.46 MeV (OH81). 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). See also (SU79F, TR79B, KE81E), (ZI78, DI80; applications) and (GA77G, BI80; theor.).
Levels of 20Ne observed in this reaction are displayed in Table 20.32 (in PDF or PS). Deuteron angular distributions have been studied at E(3He) = 9.5 to 21 MeV: see (78AJ03). See also (GR79M, MU80H; theor.).
Angular distributions have been measured at Eα = 18.5 and 28.5 MeV [see (72AJ02, 78AJ03)] and at 25.0 MeV (LE78H; t0, t1, t2). The distributions of the tritons to 20Ne*(0, 1.63, 4.25) have been analyzed by (OB74): C2S = 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). See also (BA79W).
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. 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 0.0090 ± 0.0004% [log f0t = 7.16 ± 0.02; however the transition is first-forbidden] (AL81E). The upper limit for the ground-state decay is 0.001% [log f0t > 10.5] (CA78C). For other values see Table 20.36 (in PDF or PS) in (78AJ03). The energy of the γ-ray from 20Ne*(1.63) is 1633.602 ± 0.015 keV (WA81L). 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 (AL81E). The shape of the β-spectrum has been measured by (CA78C) and compared with predictions of the CVC theory: the results are 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 (DU78F, TR78F). For the earlier work see (78AJ03). See also (QU82), (BE76GG, DE77N, CA78B) and (KI76P, OK77E, BE78BB, CA78B, HO81C, KA81N; 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] (AL81A). 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 photoneutron cross section, σ(γ, 2n), is dominated by a single peak at ~ 20.5 MeV, σmax ~ 1.1 mb (VE74D). For reactions (c) and (d) see (78AJ03) and reaction 45. See also (FL80C; theor.).
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). 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 (SZ78A; Ee = 59.5 to 119.7 MeV): the GDR cross section 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 reaction (b) see (78AJ03).
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 (78AJ03)] and at Ep = 4.5 to 7.9 MeV (FE81C; p0), 35.2 MeV (FA80A; p0) and Epol. p = 65 MeV (SA79P; p0).
Angular distributions at Ep = 24.5 and 30 MeV 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: see (78AJ03).
Angular distributions have been measured at Eα = 3.8 to 155 MeV [see (78AJ03)], at 21.7 to 23.7 MeV (PE82C) and at 25.8, 27.0 and 31.1 MeV (CO78J; α0). A coupled-channel analysis of angular distributions 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 (KN79I).
For yield measurements see (78AJ03) and (DA81H). For reaction (b) see (78AJ03) and (WA80B; 140 MeV: Sα = 0.202 ± 0.029). See also (AN81I), (RA79H; astrophys.), (MA77UU, SP80D, ST80H) and (AN78I, YO78D, CO79N, GO79T, BU82C; theor.).
Elastic angular distributions have been obtained at E(12C) = 22.2 to 42.7 MeV [see (78AJ03)] and 77.4 MeV (MO79Z) and at E(20Ne) = 65.9 MeV (DO78) and 74 and 75.2 MeV (FO79M, SH79P; back angles). See also (RI80A, SH80K). For yield and fusion measurements see (DO78, FO79M, SA79M, SH79P, CO80T, HU80G, RI80A, SK80, TS80, DE81R, SH81J, DE82F). See also (VA81B; theor.). For pion production see (NA79N). For reaction (b) see (OS81G, DE82F). See also (MA80S, ST81J), (RO78O, RO81U; astrophys.), (GO79W, SC81I) and (TR78J, VO78B, VO78F, OH80, AB81A, AN81C, RA82B; theor.).
Angular distributions have been studied at E(20Ne) = 50 MeV (ST76I) and 94.8 MeV (MO77Y, MO79Z) involving 16Og.s. and 20Ne*(0, 1.63, 4.25). Yield and fusion measurements are reported by (GA78E, SH78I, GA79A, GA79G, KO79T, RE79D, DI80A, GA80C, GA81C). For pion production see (GA81E). See also (VA79K, BR81L) and (JA79F, LE79A, OH80, AN81C, SM82B; theor.).
See (SI79I; theor.).
Elastic angular distributions are reported at E(20Ne) = 44.1 to 70.4 MeV (VA79I), 54 and 60.5 MeV (VA78B; also to 20Ne*(1.63)) and 151 MeV (VA80G). For yield and fusion measurements see (TR78A, VA78B, VA79I, VA80G, KO81M). See also (UD79, MA80Y; theor.).
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 20.33 (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). 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 (DU78F, TR81). See also (CL81B), (DE77N, GA77I, 78AJ03, RA78F) and (BE78BB, CA78B, OK80, HO81C; theor.).
Angular distributions have been measured for d0 → d3 at Ep = 14.1 and 20 MeV: see (78AJ03).
The T = 1 states observed in this reaction, and the analog states observed in 20F in the (d, 3He) reaction, are displayed in Table 20.15 (in PDF or PS). T = 0 states are presented in Table 20.34 (in PDF or PS).
Angular distributions have been reported at Ep = 26.9 to 43.7 MeV [see (78AJ03)] and at Ep = 23 MeV (AN80J; t0). 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 (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. 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).
At Ep = 40 MeV angular distributions of the tritons to 20Ne(4.97, 5.62, 7.00) [Jπ = 2-, 3-, 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).
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).
Angular distributions have been studied to many states of 20Ne at Ed = 28 and 35 MeV [see (78AJ03)] and at Ed = 28 MeV (FO78H), 54.25 MeV (YA80), 55 MeV (VE81A) and at 80 MeV (OE79A, OE80): see Table 20.35 (in PDF or PS). See also (BE78W) and (TA78; theor.).