(See Energy Level Diagrams for 20Ne)
Shell model: (1959BR1E, 1960SO1A, 1960TA1C, 1962TA14, 1963FL1A, 1963KE1B, 1963LE1C, 1963SA07, 1964BA1J, 1964BA1K, 1964IN03, 1964KE06, 1964MO1E, 1964PA1D, 1964TA1D, 1965BA1J, 1965DA1D, 1965DE1H, 1965YU1A, 1965ZA1B, 1966BA2E, 1966BA2H, 1966BA2C, 1966BO17, 1966IN01, 1966LO07, 1966RI1F, 1966ZA1E, 1967BA1W, 1967BA1K, 1967BA1V, 1967BO09, 1967EN01, 1967FE01, 1967FL13, 1967GU05, 1967HA1M, 1967LA1H, 1967MU02, 1967PA1P, 1967PA10, 1967PA12, 1967PI1B, 1967ST02, 1967ST1N, 1967ST25, 1967ST26, 1967ST1L, 1967SV1A, 1968AN1G, 1968AR02, 1968BA1L, 1969BO1Y, 1968CO11, 1968DR1B, 1968EL1C, 1968GU1E, 1968GU1C, 1968GU1G, 1968HA17, 1968HA26, 1968HA1P, 1968HE1H, 1968HI1H, 1968MO1G, 1968SA1J, 1968SA10, 1968ST06, 1968WO1A, 1969AB05, 1969AK02, 1969BA2G, 1969BA2J, 1969BA2K, 1969BE1V, 1969CO1M, 1969FA06, 1969FO1E, 1969FO04, 1969GU1E, 1969HA1Z, 1969HA45, 1969JA10, 1969KE1B, 1969KU1H, 1969LA26, 1969LE1Q, 1969MA1T, 1969PA13, 1969SA19, 1969SA1F, 1969SA1A, 1969SV1A, 1969TE04, 1969WO1G, 1969WO06, 1970AN27, 1970AR21, 1970AS1F, 1970BO1J, 1970CA24, 1970EI06, 1970FA1F, 1970FR14, 1970GI1F, 1970GI11, 1970HA49, 1970KH01, 1970KR1D, 1970KU16, 1970MC1J, 1970MC23, 1970NG01, 1970PA15, 1970PA27, 1970RO1B, 1970RU1A, 1970ST1D, 1970SV1B, 1970TE1A, 1970TU01, 1970WA39, 1970WO12, 1971AR05, 1971AR25, 1971AR1R, 1971BO29, 1971FA08, 1971FO19, 1971GU08, 1971GU1N, 1971HA1U, 1971HO23, 1971JE02, 1971KE10, 1971LA13, 1971MA22, 1971RA16, 1971SC01, 1971ST01, 1971WI01, 1971WO13, 1971ZO03, 1972LE1L, 1972RE03).
Collective and deformed models: (1959BE1A, 1960BE1A, 1962TA14, 1963FL1A, 1963KE1B, 1963LE1C, 1964BA1J, 1964BA1K, 1964KE06, 1966AB04, 1966BO17, 1967BA1V, 1967BE1V, 1967DA1G, 1967FE01, 1967KE1H, 1967KR1E, 1967LA1G, 1967PA12, 1967PA1M, 1967RI1B, 1967ST25, 1967ST1L, 1968CO11, 1968HO1G, 1968RI1M, 1968SA10, 1968ST06, 1968UN1A, 1969AB05, 1969AK02, 1969BA2G, 1969BE1V, 1969DA14, 1969HA45, 1969LE1Q, 1969VO1E, 1969WO06, 1970FA1F, 1970FR14, 1970GO1Q, 1970KH01, 1970NG01, 1970PA15, 1970RI1C, 1970SV1B, 1970VO01, 1971AR1R, 1971BO29, 1971CH22, 1971DE1R, 1971HO19, 1971HO23, 1971KE10, 1971MI02, 1971PI02, 1971ST01, 1971ZO03, 1971ZO01, 1972AB1C, 1972LE1L).
Cluster and α-particle models: (1959BE1A, 1960BE1A, 1960SH1A, 1962BO23, 1962VA1D, 1964MA1G, 1965IN1A, 1965NE1C, 1966HA33, 1966KA1A, 1968AB1B, 1968PI1A, 1968TA1G, 1969AB1B, 1969BA2E, 1969BA2L, 1969CH1P, 1969HI1B, 1969SM1A, 1969WE1J, 1970BA2B, 1970BA2H, 1970BR35, 1970EI06, 1971CH22, 1971FR06, 1971HA44, 1971KH06, 1971MC1F, 1972AB1C).
Electromagnetic transitions: (1965GR1H, 1965NE1C, 1965ST22, 1967GU1D, 1967HS1A, 1967KA06, 1967KU1E, 1968AN1G, 1968EL1C, 1968GU1G, 1968HA17, 1969AB05, 1969AK02, 1969BE1V, 1969CU07, 1969FO1E, 1969HA1Y, 1969HA1Z, 1969HA1F, 1969HI1B, 1969JA10, 1969LA26, 1970AN27, 1970HA49, 1971AR05, 1971AR25, 1971FO19, 1971GU1N, 1971HA44).
Special levels:(1960SH1A, 1961BA1D, 1961TR1B, 1964BA1J, 1964BA1K, 1964EN1A, 1964MI16, 1964TA1D, 1966BA42, 1966BO17, 1966BR1H, 1966LO07, 1966ZA1E, 1967EN01, 1968AN1G, 1968AR02, 1968HA1P, 1968SA1J, 1969AK02, 1969BO1Z, 1969HA1Y, 1969HA1G, 1969HA1F, 1969JA10, 1969ST1J, 1969TE04, 1969WO06, 1970AN27, 1970AR21, BA70W, 1970GO1Q, 1970HO17, 1970RO1B, 1970RU1A, 1970TE1A, 1971AR1R, 1971BO1F, 1971FA08, 1971GU08, 1971LE30, 1971SE1C, 1971ST36).
Pion and kaon capture and reactions: (1970GA1K).
Other topics:(1960EV1A, 1960SO1A, 1961BA1D, 1962CH12, 1963DA1C, 1963EV01, 1964AB1A, 1964BR1H, 1964EN1A, 1964IN03, 1964KA1A, 1964MO1E, 1965DE1H, 1965YO1A, 1966DA1E, 1966GI1A, 1966IN01, 1966SU1D, 1966YO1B, 1967AB03, 1967BA1W, 1967BR1G, 1967FL13, 1967GU05, 1967GU1D, 1967KA06, 1967KE1H, 1967PA1P, 1967ST02, 1967ST1N, 1967ST25, 1967ST26, 1968DA1P, 1968DR1B, 1968DW1A, 1968FL1C, 1968GU1E, 1968GU1C, 1968GU1G, 1968HE1H, 1968MO1G, 1968PA1Q, 1968SA10, 1968TA1G, 1968WO1A, 1969BA2G, 1969BA2J, 1969BA2K, 1969BO1Z, 1969DE15, 1969KE1B, 1969LA26, 1969MA1T, 1969RU04, 1969SH1E, 1969SO08, 1969WO06, 1970BO1J, 1970DA13, 1970FO1K, 1970GM1A, 1970GO1R, 1970PA15, 1970RU1A, 1970RU1B, 1970ST19, 1970TU01, 1970VO01, 1971FA13, 1971FO04, 1971FR1B, 1971GO36, 1971HA14, 1971HO19, 1971HO23, 1971JE02, 1971LA13, 1971MI02, 1971SC01, 1971SE1C, 1971ST01, 1971ZO03, 1972LE1L, 1972RE03).
See also (1967BA1V, 1967GU1D, 1967LA1G, 1967SH14, 1967ST26, 1968EL1C, 1968RI1M, 1969BA2J, 1969CO1M, 1969FO1E, 1969FO04, 1969FU11, 1969HI1B, 1969KE1B, 1969LA26, 1969SA19, 1969SA1F, 1970GO1R, 1970KH01, 1970RU1B, 1970ST19, 1970TU01, 1970VO01, 1971AR25, 1971BO29, 1971FO19, 1971GU1N, 1971LA13, 1971RA16, 1971SC01, 1971ST01, 1971TE1C, 1971WI01, 1971ZO03, 1972LE1L).
B(E2)(0+ → 2+) = 0.048 ± 0.007 e2 · b2 (1970NA07).
Particle group and γ-ray energy measurements have been made for many states of 20Ne: see Table 20.16 (in PDF or PS) (1961AL12, 1964PE02, 1966KU03, 1967KU04, 1970PA08, 1971HA26, 1971MI09, 1971MI1J, 1971PA1C, 1971SC12). Angular correlation (1961GO12, 1962KU03, 1964KU03, 1966KU03, 1967KU04, 1967SM04, 1971SC12) and γ-ray branching measurements [see Table 20.17 (in PDF or PS)] (1964BR18, 1967BR22, 1967SM04, 1971HA26) lead to the Jπ assignments shown in Table 20.16 (in PDF or PS), which also show level assignments to rotational bands. See also (1962BR35, 1964AL15, 1966BR1T).
At E(12C) = 22.0 to 35.0 MeV the α-spectra are dominated by the group corresponding to the 2+ state at Ex = 7.83 MeV. Both 20Ne*(7.83) and 20Ne*(7.20) [Jπ = 0+] are much more strongly excited than the 0+ and 2+ states at Ex = 6.72 and 7.42 MeV. At E(12C) = 25 and 27 MeV, the distributions of the α-particles to 20Ne*(7.83) is barely oscillatory and is strongly forward peaked, indicating a direct interaction, while the distributions to 20Ne*(7.42) are compound nuclear in character. This is consistent with the hypothesis that 20Ne*(7.20, 7.83) are quartet states of the configuration (220) [two sd-shell α-particles outside a 12C core], populated via a "semi-direct" mechanism that proceeds through the formation of doorway states in the incident channel (1971MI09). See also (1970AR21, 1971MI1J, 1971MI11). At E(12C) = 50 MeV, compound nucleus formation dominates (1971HA1D). Angular distributions are also reported at E(12C) = 5.6 to 6.2 MeV (1963AL07; α0 → α3, α4+5), 10.6 to 12.4 MeV (1963KU05; α0), 12.5 MeV (1961PO13; α0, α1), ≈ 20.0 to ≈ 28.4 MeV (1964BO35; α0), 20.3 to 25.6 MeV (1964AL17, 1964VO03; α0, α1), 21.5 to 28.3 MeV (1964BO35; α1) and 50 MeV (1970PA08, 1971PA1C; α0, α5, α10). See also (1972NO01; theor.).
(1969PA22) have studied the yield of this reaction to permit predictions of the cross section in the energy region of interest in stellar carbon burning. The importance of this reaction for astrophysical work is discussed by (1969AR1F). See also 24Mg in (1973ENVA).
At E(14N) = 52 and 60 MeV the reaction appears to proceed via the direct transfer of eight nucleons. Angular distributions have been reported for the 6Li ions corresponding to 20Ne*(0, 1.63, 4.25, 4.97, 5.62, 7.01) (1971MA23). Assignment of observed states to rotational bands is discussed by (1971MA23, 1971NA17).
Observed resonances in the yield of capture γ-rays over the range Eα = 0.8 to 10 MeV are displayed in Table 20.19 (in PDF or PS) (1964PE05, 1965VA14, 1967LI07, 1969GR03, 1972AL05, 1971DI08, 1971RO13, 1971RO33, 1971TO06, 1971TO1C). Information on the character of the radiative decay is shown in Table 20.17 (in PDF or PS).
No resonances have been observed below Eα = 1 MeV: for Eres < 0.85 MeV, (2J + 1)ΓαΓγ/Γ ≤ 0.044 eV, and (2J + 1)ΓαΓγ1/Γ ≤ 0.031 eV; for Eres < 1.00 MeV, ωγ ≤ 0.036 eV and ωγ1 ≤ 0.024 eV (1971TO06, 1971TO1C). The astrophysical implications of this reaction are discussed in (1970TO1F, 1971TO06, 1971TO1C). See also (1957BU1B) and (1965ME10, 1967WI1B).
The Jπ = 5- states 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 (1971RO33). 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 (1971DI08, 1971RO13). 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 (1972AL05).
Excitation functions have been measured over a wide energy range for elastically 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). See also (1964BO1E, 1965CA02) and (1963DA1D). Angular distributions of various α-particle groups are reported for Eα = 5.0 to 104 MeV: see Table 16.27 (in PDF or PS) in (1971AJ02).
A number of anomalies are observed in the elastic scattering. Phase shift analyses lead to the results shown in Table 20.21 (in PDF or PS) (1953CA44, 1960MC09, 1964PE05, 1965MC02, 1967HU06, 1967ME10, 1969JO18, 1971BE17, 1972HA07, 1971TA05). At higher energies, a prominent 2 MeV wide resonance is observed corresponding to 20Ne*(28.) with Jπ = 8+ (1969CO19, 1970CO13). In the range Eα = 37 to 51 MeV, the cross section for elastic scattering appears to decrease monotonically (1965VA11). Identifying various of the observed states as members of different rotational bands is discussed by (1967HU06, 1972HA07): see also Table 20.15 (in PDF or PS). The Jπ = 6+, 8+ and 7+ states at Ex = 8.78, 11.95 and 13.33 MeV are probable members of the lowest rotational bands with Kπ = 0+ and Kπ = 2+. The known reduced widths in both bands are small, indicating that the bands should be describable in terms of the spherical shell model. The reduced widths within each band are found to decrease sharply with increasing spin (1972HA07). See also (1963NO1C, 1968CE1B, 1969AG06) and (1968SH1G, 1969PI02, 1971MC03; theor.).
Reaction (b) can be described in terms of both sequential and one-step knockout processes. A state at Ex ≈ 24 MeV in 20Ne may be involved (1968PA12). Reaction (c) to 12C*(0, 4.4) has been studied for Eα = 35.5 to 41.9 MeV. The results are qualitatively consistent with the statistical theory of compound nuclear reactions, with an average width of 1.1 MeV for the compound states (1965BR13). See also (1971GO1U). For spallation reactions see (1968JA1J, 1969JU03).
Deuteron groups have been observed to all 20Ne states below 7.2 MeV (1968HE08, 1968RO1K, 1969GO18). (1969BE1X) report the strong excitation of 20Ne*(8.78, 10.30, 12.64, 13.96, 14.35, 15.34) while 20Ne*(11.95), the 8+ member of the ground state rotational band is comparitively weakly populated. Angular distributions have been measured at E(6Li) = 5.50, 5.70 and 6.22 MeV (1968GR22; α0, α1 - the latter is isotropic), 20.0 MeV (1968HE08: all states below Ex = 7 MeV), 25.8 MeV (1969GO18, 1970OG1A: Ex = 0, 1.6, 4.3, 5.8, 7.2, 8.8, 10.3, 12.7, 15.6). The reaction proceeds to a large extent by compound nucleus formation. Even at E(6Li) = 34 MeV, a large compound nuclear contribution is reported (1971HA1D). This is consistent also with d1-γ angular correlation work at E(6Li) = 15 MeV (1971BA24).
The lifetime of 20Ne*(1.63), τm, is 1.27 ± 0.24 psec, as determined in this reaction and in reaction 14 (1969TH01). See also (1968OG1A) and (1965ZE1B, 1969CH1K, 1969CH1Q, 1969JA08, 1969SM1A, 1970DO07; theor.).
At E(7Li) = 16 MeV, this reaction excites only those rotational states which are allowed by the selection rules in the SU3 scheme. The reaction appears to proceed mainly by a direct stripping mechanism. Relative maximum cross sections for formation of 20Ne*(0, 1.63, 4.25, 5.62, 5.79) are 100, 272, 171, 39, 82 while the unresolved 20Ne*(7.17, 7.20) states are formed with a relative cross section of 486 (1968MI01). Angular distributions are also reported at E(7Li) = 15.0 MeV (1970MI1E, 1970NE18; t0 → t2), 20.0 MeV (1970NE18; t2) and 30.3 MeV (1969GO18, 1970OG1A: same states as in reaction 13). Angular correlation work [t1-γ and t2-γ at E(7Li) = 13, 14 MeV] shows some indication of competition between an α-particle transfer process and either multistep or compound nuclear processes (1971BA24). See also (1968OG1A, 1971HA1D) and (1969DA14, 1970DO07, 1971AR1R; theor.).
The ground state excitation function 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 (1969CO19). See also (1965WA1D).
Neutron groups have been observed to a number of 20Ne states: see Table 20.22 (in PDF or PS) (1969AD02, 1970GU08). In particular the first T = 1 state in 20Ne is reported at Ex = 10.25 ± 0.05 MeV (Jπ = 2+) (1970GU08) and the first T = 2 state is found at Ex = 16.730 ± 0.006 MeV (Jπ = 0+) (1969AD02). See also (1969BA1Z).
Angular distributions have been measured at E(3He) = 2.80 to 4.64 MeV (1971DI12), 3.1 MeV (1970GU08), 4 MeV (1970TA08) and 5.70 and 7.33 MeV (1969AD02). See also (1964DI1C, 1967AD01, 1967BE1W) and (1969TO1E; theor.).
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 (1967SE02). See also (1959GE34, 1960BR35, 1964TA05, 1965TA1E, 1966ME1H, 1966PA1K).
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 (1967KU06). For Ep = 5.65 to 6.21 MeV, the γ0, γ1, γ2, γ3, γ4 and γ5 yields are not resonant but the yield of 10.6 MeV γ-rays is resonant at 5.878 ± 0.005 MeV [Γlab = 11 ± 3 keV; ΓpΓγ/Γ ≈ 0.055 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*(12.25), to the 2+ state at 1.63 MeV (1968LA1H). See also (1968HA1T, 1968HA1U, 1969HA1Y).
These and other resonances observed at lower energies are displayed in Table 20.23 (in PDF or PS) (1954SI07, 1955FA1A, 1960KA18, 1961ET01, 1961GO21, 1962KE03, 1963BE19). 20Ne*(13.48) (Ep = 0.67 MeV) decays predominantly to 20Ne*(1.63). [See Table 20.17 (in PDF or PS) for branching ratios.] The radiation is M1 and the angular distribution of the 11.9 MeV γ-rays is approx. isotropic: Jπ = 1+ (1955FA1A, 1960KA18, 1961GO21). 20Ne*(13.88) [Ep = 1.09 MeV] decays predominantly to 20Ne*(4.97) (1961GO21). See also (1959AJ76) and (1969HO1W; theor.). For astrophysical considerations see (1969BA71).
The elastic scattering has been studied in the range Ep = 500 to 2000 keV by (1954DE1A, 1954PE1A, 1955BA1C, 1955WE1A, 1956DE33, 1963BE19). Parameters for the observed resonances are exhibited in Tables 20.24 (in PDF or PS) and 20.25 (in PDF or PS) taken mainly from (1955BA1C). Some unresolved structure is observed at Ep = 900, 1092 and 1137 keV, in addition to a broad structure near Ep = 1700 keV (1955WE1A). A sharp anomaly is observed in the elastic scattering at Ep = 4.096 ± 0.003 MeV (1967BL19), 4.090 ± 0.005 MeV (1967KU06). It is an s-wave resonance corresponding to the 0+; T = 2 state at Ex = 16.73 MeV (1967BL19, 1967KU06). There is no indication of this resonance in the p3, p4 or p5 yields (1967KU06). The amplitude of the T = 1 or T = 0 impurity in this state is ≈ 1.5% (1967BL19). In the range Ep = 5.65 to 6.21 MeV, a single anomaly is seen in the elastic scattering at Ep = 5.880 ± 0.005 MeV. The interference patterns show that the scattering is d-wave, corresponding to the excitation of the Jπ = 2+; T = 2 state at Ex = 18.43 MeV (1968LA1H). The parameters of these two T = 2 states are shown in Table 20.24 (in PDF or PS). The elastic scattering has also been studied for Ep = 4.2 to 7.5 MeV by (1967TH06), and the polarization has been determined at Ep = 10.2 MeV by (1961RO05). The total reaction cross section is reported for Ep = 24.6 to 46.0 MeV by (1969MC1A).
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 20.26 (in PDF or PS) (1955BA94, 1963BE19). See also (1958RA15). 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 (1967TH06). For a spallation study, see (1969EP1B). See also (1959TR1A, 1969LE08), (1969HA1Y, 1969MC1C, 1969TE1A), (1963MI1D, 1966AM1B, 1967AF01; theor.), (1959AJ76) and 19F.
For Ep ≈ 1 to 3 MeV, five α-particle groups are reported. All show resonance effects with relative intensities varying greatly with bombarding energy. The long range group (α0) leaves 16O in the ground state (Jπ = 0+); the next longest (απ) results in the formation of the Jπ = 0+ nuclear pair-emitting state at 6.05 MeV, while the three remaining groups (α1, α2, α3) lead to γ-ray emitting states at 6.13 (Jπ = 3-), 6.92 (Jπ = 2+) and 7.12 MeV (Jπ = 1-). At Ep > 3 MeV, excitation of higher 16O levels occurs: see 16O. Resonances for α0 and απ (Tables 20.27 (in PDF or PS) and 20.28 (in PDF or PS)) are generally identical and different from those for α1, α2, α3 (Table 20.29 (in PDF or PS)). The resonances for α0 and απ are required to have even J, even π of odd J, odd π while the α1, α2, α3 resonances, insofar as their assignments are known, are all odd-even or even-odd.
Recent studies of the α0 yield and of angular distributions have been carried out by (1959BR67: Ep = 0.40 to 0.72 MeV), (1964BR12: Ep = 2.0 to 3.3 MeV), (1966MO25: Ep = 2.24 to 3.35 MeV), (1963WA12: Ep = 3.3 to 12.2 MeV), (1965WA08: Ep = 4.0 to 12.0 MeV), (1960BR35: Ep = 4.2 to 8.8 MeV), (1968LA1H: Ep ≈ 5.9 MeV), and (1959OG15: Ep = 12.9 to 14.1 MeV). See also (1969LE08). Resonances observed in the lower energy range are displayed in Table 20.27 (in PDF or PS) (1957CL42, 1958IS10, 1958IS11, 1958RA15, 1959BR67, 1964BR12, 1968LA1H). Among these is a resonance at Ep = 5.880 ± 0.005 MeV, Γlab = 11 ± 3 keV which corresponds to the Jπ = 2+; T = 2 state at Ex = 18.43 MeV: the α1 and α2 channels also display it (1968LA1H). See also (1968HA1T, 1969HA1Y, 1969MC1C). (1965WA08) find that over the range Ep = 4.0 to 12.0 MeV, direct interaction mechanisms are predominant although compound nuclear contributions cannot be ignored at certain energies. The continuing structure in the α0 yield at the higher energies has been interpreted by (1964TE1F) in terms of fluctuations with a coherence energy Γ = 160 keV. See also (1966MO25).
Resonances in the 19F(p, απ)16O yield have been investigated by (1950CH53, 1951PH1A, 1954DE36, 1958IS11, 1958RA15): see Table 20.28 (in PDF or PS). Resonance locations and absolute reduced widths appear to correspond closely to those for (p, α0), although some exceptions occur. In the work of (1958RA15) only 6 of the 23 (p, α0) resonances have no clear counterpart in σ(p, απ). For resonances at Ep = 1.35, 1.72, 1.88 and 2.33 MeV, θ2α0 = θ2απ within about 10%; at Ep = 2.17 MeV, a large difference occurs, possibly to be ascribed to superposition of several resonances (1958RA15). Below Ep = 1.3 MeV, several fairly large differences occur (1958IS11).
Recent yield measurements of α-groups to excited states of 16O and of the de-excitation γ-rays are reported by (1965AS07: Ep = 0.9 to 2.6 MeV; α1, α2, α3), (1969OS1B: Ep = 1.9 to 4.2 MeV; σt for 6.13, 6.92, 7.12, 8.87 γ), (1963WA12: Ep = 10 to 12 MeV; α1+2, α3+4) and (1971GO1U: Ep = 2 to 6.2 MeV; α0, α1, α2, α3, α4). See also (1961AS02). Resonances are displayed in Table 20.29 (in PDF or PS) (1950AR1A, 1950BA1A, 1950CH1A, 1952WI1A, 1955BA94, 1955HU1A, 1955KI28, 1959BO14, 1959KU79, 1959LI51, 1960HU11, 1962KE03, 1962RY01, 1963BE19, 1964SE1A, 1965AS07, 1966MA60, 1967KU06). Anomalies are observed in the α0, α1, α2, α3 and α4 yields at Ep = 4.09 and 5.88 MeV, corresponding to the T = 2 state at Ex = 16.73 and 18.43 MeV. [P. Gorodetzky, private communication.] See also (1967KU06).
The total cross section has been measured for Ep = 5.1 to 6.5 MeV by (1960TE03). For spallation measurements see (1963VA1C). See also (1959TR1A, 1960GO12, 1961ET01, 1968KO05, 1970WI13, 1971GU23) and (1963MI1D; theor.). For astrophysical considerations, see (1969BA71). See also 16O in (1971AJ02) and (1959AJ76).
Yield measurements are reported for Ep = 4.23 to 4.93 MeV (1959GI47; σt), 4.23 to 6.01 MeV (1968RI08; σt), 4.4 to 6.1 MeV (1969BL02; γ1, γ2), 4.9 to 11.0 MeV (1963JE04; σt) and 6.2 to 6.9 MeV (1962FR09; n0, n1+2, n3, n4). See also (1965VA1E, 1968LA1H). Observed resonances are displayed in Table 20.30 (in PDF or PS) (1952WI1A, 1963JE04, 1968RI08). A narrow anomaly is reported in the n0 and n1 yield at Ep = 5.879 ± 0.004 MeV corresponding to a state at Ex = 18.427 MeV in 20Ne, presumed to be the second T = 2 state in 20Ne (1968AD1C). See also (1959AJ76) and 19Ne.
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 (1969GO1B, 1971GO1U). It is suggested that most of the observed states are of 8p-4h and 12p-8h configurations (1971GO1U).
Levels of 20Ne derived from reported neutron groups are listed in Table 20.31 (in PDF or PS) (1958MO02, 1963FE1B, 1964SA09, 1966RI05, 1968LA03, 1969RI01); those derived from threshold measurements are displayed in Table 20.32 (in PDF or PS) (1960BU07). Gamma-ray measurements have been reported by (1960KR02, 1960RA23, 1965PE01) and angular correlation measurements by (1964SA09, 1966RI05). For a survey of the earlier work see (1959AJ76).
Angular distributions have been measured at Ed = 0.5 to 0.7 MeV (1964SA09; n to 20Ne*(10.31)), 1.0 MeV (1966RI05; n to 20Ne*(10.31, 11.03)), 1.0 to 1.3 MeV (1962FI02; n0, n1), 1.0 to 2.5 MeV (1966WA17; n0, n1), 2.17 MeV (1958MO02; n0 → n4), 2.5 and 3.0 MeV (1963FE1B; n0, n1 and n to 20Ne*(5.80, 6.75, 8.76)), 2.51 to 3.31 MeV (1964SI09; n0 → n3, n4+5, n6), 2.98 MeV (1968LA03: see Table 20.31 (in PDF or PS)), 3.06 to 6.07 MeV (1967BA40; n0, n1), 3.57 MeV (1961BE10; n0 → n3, n4+5, n6) and 5.10 MeV (1969RI01: see Table 20.31 (in PDF or PS)). See (1959AJ76) for earlier references. See also (1963FE01, 1964AL14, 1964JO04, 1965BA1K), (1966WE1B) and (1966AR1D, 1966IN01, 1968WA1M, 1970BO1K; theor.).
At E(3He) = 9.5 to 10.0 MeV, angular distributions have been measured for the deuterons corresponding to 20Ne*(0, 1.63, 4.25, 4.97, 5.62, 5.79, 6.72, 7.01, 7.17 + 7.20, 7.42). The distributions to 20Ne*(0, 1.63, 5.79, 6.72, 7.42) have been fitted with l = 0, 2, 1, 0 and 2, respectively. Spectroscopic factors were also obtained. The results are consistent with the description of the states in terms of rotational bands (1965SI18). Angular distributions are also reported at E(3He) = 13.0 MeV (1963JA01; d0, d1).
Gamma-ray measurements lead to Ex = 1635.3 ± 1.8, 4249 ± 2.5, 4968 ± 3, 5623 ± 3 and 7174 ± 4 keV and to τm = 1500+900-400, 150 ± 25 and 2800+2400-900 fsec, respectively, for 20Ne*(1.63, 4.25, 4.97) (1969AN08, 1969AN1J: see also Table 20.18 (in PDF or PS)). See also (1964HE1D, 1966AR1D, 1966IN01, 1970BO1K; theor.).
At Eα = 28.5 MeV, angular distributions are reported for the tritons to 20Ne*(0, 1.63, 4.25, 4.97, 5.62 + 5.79, 7.02 + 7.17 + 7.20). All are typical of stripping reactions except that for 20Ne*(4.97). The distributions have been analyzed by DWBA. 20Ne*(6.72) is very weakly populated (1967HA23). Angular distributions have also been reported at Eα = 18.5 MeV (1963JA01; t0, t1) and 28.4 MeV (1965KA14; t0, t1, t2, t3, t4+5). See also (1964EL1B; theor.).
The decay is principally to 20Ne*(1.63) with a half-life of 11.03 ± 0.06 sec: see Table 20.5 (in PDF or PS) for a listing of half-life measurements and Table 20.33 (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 (1969GA05), as are measurements of the β-γ circularly polarized correlation (1961FR02, 1965MA28).
Eβ-(max) = 5.419 ± 0.013 MeV (1954WO23), 5.416 ± 0.015 MeV (1959AL06). The energy of the subsequent γ-ray is 1634.8 ± 0.6 keV (1967VA08), 1632.6 ± 0.8 keV (1966AL12). The γ-ray from the (4.97 → 1.63) transition has Eγ = 3334.3 ± 0.7 keV. When recoil-corrected, ΔE = 3334.6 ± 0.7 keV, and using the Ex for 20Ne*(1.63) shown in Table 20.15 (in PDF or PS), Ex for 20Ne*(4.97) = 4968.4 ± 0.8 keV (1969GA05). See also (1960SC01, 1961OK1A, 1968SP01, 1971TO1K), (1959AJ76) and (1967YA04, 1968KR10, 1969BL1D, 1969SU12, 1970AN27, 1970MC23, 1970YA01, 1971LI1H, 1971WI18, 1971YA04; theor.).
The 20Ne charge radius, rrms = 3.116 ± 0.025 fm (using a Born approx.) (1971MO15).
At Ee = 39 and 56 MeV, the 180° inelastic scattering is dominated by the transitiion 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 Ex = 11.58 ± 0.03 MeV [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 (1971BE18). See also (1963BA19, 1963GO04) and (1971FO19, 1971HO20; theor.). 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 [Γ = 0.50, 0.58, 0.54 and 0.49 MeV, respectively], as well as some weaker structures (1962DO1A). See also (1961DO08) and (1970PA1H; theor.).
Angular distributions have been measured at Ep = 2.15 and 2.72 MeV (1961SO02; p1, γ1), 3.65 to 4.35 MeV (1963HU1D; p0, p1), 4.95 to 5.50 MeV (1959OD08; p0, p1), 5.20 to 6.23 MeV (1962HU12; p0, p1), 6.86 to 7.15 MeV (1969MC14; p0), 7.75 to 14.2 MeV (1960OD01; p0, p1), 17.4 MeV (1962SC12; p1, p2, p3, and p to states with Ex = 5.63 ± 0.07, 7.45 ± 0.08, 7.85 ± 0.08, 9.20 ± 0.09, 10.0 ± 0.1 MeV), 18.03 MeV (1969LE1P; p0), 24.5 MeV (1969DE15; p0, p1, p2, p to 20Ne*(8.78)) and 41.8 MeV (1970FA17; p0). A large hexadecapole deformation, β4, is needed to reproduce both the shapes and the intensities of the angular distributions to the 2+, 4+ and 6+ members of the ground state rotational band [20Ne*(1.63, 4.25, 8.78)] (1969DE15). Polarization measurements have been carried out at Ep = 3.8 to 5.1 MeV (1967BE25; p0), 8.0 MeV (1961RO13; p0), 14.5 MeV (1966RO1R; p0) and 24.5 MeV (1970BA2F, 1971BA1T; p0, p1, p2, p3).
Angular distributions are reported at Ed = 10.95 MeV (1960TA08; d0), 11.6 MeV (1965JA13; d0, d1, d2, d4+5), 11.8 MeV (1966JA1J; d0, d1) and 52 MeV (1968HI09, 1968HI1B; d0, d1, d2, d4+5, and d to 20Ne*(7.2, 10.5)). The second excited state has Ex = 4.250 ± 0.008 MeV (1960FR04). See also (1960EL09, 1966WE04, 1968ME1E, 1971DU12; theor.).
The elastic scattering has been studied at Et = 1.80 and 2.00 MeV (1969HE08).
Angular distributions of elastically scattered 3He particles have been measured at E(3He) = 10 and 15 MeV (1969BA62), 15 MeV (1969ZU02), 17.83 MeV (1971KE11), 28 MeV (1960CA1C) and 35 MeV (1969AR08, 1969AR10). See also (1960CA10, 1962AG01). At E(3He) = 17.83 MeV, angular distributions of the 3He's corresponding to 20Ne*(1.63, 4.25) [Jπ = 2+ and 4+, respectively] have been analyzed by a coupled channels calculation. For 20Ne*(1.63), β2 is in the range 0.42 to 0.48; for 20Ne*(4.25), β4 < 0.05 (1971KE11). See also (1964VE1A, 1968HO1C; theor.).
Angular distributions have been measured at Eα = 12.7 to 15.2 MeV (1967IV02, 1970BU25, 1970IV04; α0, α1, α2, α3, α4+5), 16.8 MeV (1970FR1F; α0, α1, α2), 18.0 MeV (1958SE51, 1966LU02; α0, α1 ), 20.2 to 23.3 MeV (1970AG08, 1970FE09, 1970PI1G; α0, α1), 20.5 to 23.2 MeV (1971TA20; α0), 20.9 to 24.0 MeV (1966SE1G, 1967GH1A; α0, α1, α2), 21.6 MeV (1968TA1Q; α0), 22 MeV (1962EI04; α0, α1, α2, α3, α4+5), 22.5 MeV (1970LA20; α0, α1), 27.3 MeV (1964KO02, 1965KO07, 1965KO1A, 1967KO1J; α0, α1, α2. α3, α4+5), 31.8 MeV (1959MC1A; α0, α1, α2), 33.0 MeV (1967RE1B, 1968RE1F; α0 → α5 and α to 20Ne*(7.17)), 44 MeV (1968FA1A; α0), 50.9 MeV (1965SP02, 1965SP1E, 1967RE1B, 1968RE1F; α0, α1, α2, α3, α4, α5, α to 20Ne*(7.17)), 80.8 MeV (1967RE1B, 1968RE1F; α0, α1, α2, α3, α4+5) and 104 MeV (1969HA14, 1970SP01, 1971RE09; α0, α1, α2). At Eα = 104 MeV the quadrupole and hexadecapole deformation lengths have been determined (1969HA14, 1970SP01, 1971RE09). The γ-decay of several 20Ne states is reported by (1962EI04): see Table 20.17 (in PDF or PS). See also (1963CR01, 1963MI1C, 1968SP04) and (1959BL31, 1961EI1A, 1962HU1A, 1964GR1L, 1964VE1A, 1965FA1D, 1965SA1G, 1967RA1E, 1971GO28, 1971OB1A; theor.).
The static quadrupole moment of 20Ne*(1.63) has been determined to be Q0 = +0.94 ± 0.38 b (1969SC08).
20Na decays to a number of states of 20Ne: see Table 20.34 (in PDF or PS) (1967PO11, 1967SU05, 1964MA44). The half-life of 20Na is τ1/2 = 446 ± 3 msec [see 20Na]. The ratio of the mirror decays 20Na → 20Ne*(1.63) and 20F → 20Ne*(1.63), (ft)+/(ft)- = 1.054 ± 0.023. If this number is directly interpreted in terms of second-class currents, the induced tensor coupling constant gIT = (1.5 ± 0.6) × 10-3 (1970WI05, 1971WI07).
The line shapes of the α-spectra from the decay of 20Ne*(7.42, 10.26) are fitted by Gamow-Teller and by Fermi decay theory. The former indicates some evidence for longitudinal nuclear alignment of β-recoils (1971MA09). See also (1970OA01, 1971TO1K, 1971TO1L) and (1971HO1D, 1971LI1H; theor.).
At Ep = 20 MeV, the angular distribution of the deuterons to 20Ne*(1.63) [very strongly populated] is characterized by ln = = 2 while that of the d2 group (to 20Ne*(4.25)) is suggestive of a weak ln = = 2 component. All of the observed ln = 1 pick up strength is associated with 20Ne*(4.97) (1970HO1R). See also (1969HE1T).
Angular distributions have been reported at Ep = 26.9, 35.1 and 42.4 MeV (1971FA07; t0, t1, t2, t3, t4+5, t6) and at 43.7 MeV (1964CE05). 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 (1969HA38)] 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 (1964CE05). 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 (1970MC04). The ratios of the cross section for formation of the analog states 20Ne*(10.26)/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 (1969HA19). See also (1970OL1B) and (1969TO1E; theor.).
Angular distributions have been obtained at Eα = 42 MeV for the transitions to 20Ne*(0, 1.63, 4.25) (1970AR1H).
Alpha-particle groups have been observed to the ground state and to 20Ne states with Ex = 1.634 ± 0.004 MeV (1953DO04), 1.635 ± 0.006, 4.248 ± 0.006, 4.969 ± 0.006 and 5.631 ± 0.006 MeV (1957BU36). An attempt has been made to see if 20Ne*(4.97) could consist of unresolved states: the result was negative (1965ME10). Angular distributions have been measured at Ep = 10.0 MeV (1963WA10; α0 → α3) and at 45.5 MeV (1969KO09; α0).
The cross over transitions from 20Ne*(4.25, 4.97) are ≤ 9% and ≤ 4%, respectively, of the cascade transition via 20Ne*(1.63) (1959KR66, 1960KR02): see Table 20.17 (in PDF or PS). See also (1960RA23). The lifetime, τm, of 20Ne*(1.63) = 0.76 ± 0.33 psec (1956DE22): see also Table 20.18 (in PDF or PS). See also (1959AJ76) and (1961AD01).
At E(3He) = 40.7 MeV, the ground state angular distribution has been measured by (1969OH1B).
At Ed = 55 MeV, 20Ne*(0, 1.63, 4.25) [Jπ = 0+, 2+, and 4+, respectively] and 20Ne*(4.97, 5.62) [Jπ = 2- and 3-, respectively] are strongly populated, while 20Ne*(5.79) is weakly populated, as predicted by the SU3 model. The results are similar to those from 16O(7Li, t)20Ne (reaction 14) (1971MC04).