
^{20}Ne (1998TI06)(See Energy Level Diagrams for ^{20}Ne) GENERAL: See 3 [Electromagnetic Transitions in A = 20] (in PDF or PS), 20.16 [General Table] (in PDF or PS), 20.17 [Table of Energy Levels] (in PDF or PS) and 20.18 [Radiative decays in ^{20}Ne] (in PDF or PS).
μ_{1.63} = 1.08 ± 0.08 nm (1989RA17). B(E2)(↑) [0 → 1.63] = 0.0330 ± 0.0015 e^{2} · b^{2} (1978GR06). See also (1987RA01). Intrinsic hexadecapole moment: Q_{4.25} = 0.022 ± 0.003 e^{2} · b^{2} (1978GR06). μ_{4.25} = 0.52 ± 0.60 nm (1989RA17). Isotopic abundance: (90.51 ± 0.09)% (1984DE53).
Observation of ^{20}Ne in this reaction and measurement of the cross section was reported by (1990BEYY).
Excitation functions have been measured for E(^{10}B) = 6 to 30 MeV (reaction (a)) and 6 to 20 MeV (reaction (b)). Large resonant structures are observed in reaction (b), particularly at E_{x} ≈ 38 MeV (α_{0}) and 38.6 MeV (α to ^{16}O* (7.0, 10.3, 16.2 (u)), Γ ≈ 0.6 MeV. See also (1983KAZF) and (1978AJ03). More recently, cross sections for fusion of ^{10}B + ^{10}B were measured for E(^{10}B) = 1.5  5 MeV/nucleon, and evidence for fissionlike decay of ^{20}Ne was observed (1989SZ01). Mass distributions from the sequential decay of the compound nucleus measured at E(^{10}B) ≈ 110 MeV show no evidence for nuclear structure effects (1993SZ02).
Angular distributions of αparticles to many states of ^{20}Ne below E_{x} = 10.7 MeV have been measured at E(^{14}N) = 23.5 to 35 MeV. See also (1978AJ03, 1983AJ01). Numerical calculations of differential cross sections using CWBA and DWBA are reported by (1990OS1B).
At E(^{16}O) = 19.5 to 42 MeV angular distributions for the ^{6}Li ions corresponding to transitions to ^{20}Ne*(0, 1.63, 4.25, 4.97, 5.62 + 5.79, 6.7  7.2) are in good agreement with HauserFeshbach calculations. See also (1978AJ03, 1985ST1B).
At E(^{11}B) = 115 MeV, angular distributions are reported to ^{20}Ne*(7.16, 8.78, 10.26, 11.95, 15.4). ^{20}Ne*(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 J^{π} = 6^{+}, 7^{}, (8^{+}), 9^{}, and 9^{}: see (1983AJ01).
At E(^{9}Be) = 16 and 24 MeV, angular distributions have been measured for ^{20}Ne*(7.3 ± 0.4, 9.2 ± 0.4, 10.9 ± 0.3, 12.2 ± 0.3, 15.7 ± 0.3): see (1983AJ01).
At E(^{12}C) = 45 MeV the population of states of ^{20}Ne with E_{x} = 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 (1976KL03). [Values in brackets are J^{π} suggested on basis of HauserFeshbach calculations. The underlined states are well resolved: the authors indicate ± 20 keV for such states.] The relative intensities of the groups to ^{20}Ne*(17.39, 15.38) [J^{π} = 9^{}, 7^{}] argue against the existence of a superband: see (1978AJ03). See also (1983AJ01).
Double and triple (α, α, γ) correlations and γray branching measurements [see 20.18 (in PDF or PS)] lead to the J^{π} assignments shown in 20.19 (in PDF or PS). See 20.20 (in PDF or PS) for assignments to rotational bands. Angular distributions for many states have been reported at E(^{12}C) = 4.9 to 51 MeV [see (1978AJ03, 1983AJ01, 1987AJ02)], at 5.2 to 5.8 MeV (1988BA12; α_{0}), and at 69.5 MeV (1985XI1B). At E(^{12}C) = 38 to 64 MeV, ^{20}Ne*(7.17, 7.83, 8.54, 8.78, 9.03, 11.95, 12.13, 12.59, 13.90) are strongly populated and subsequently decay to ^{16}O_{g.s.} (1987RA02). Alpha decay of the J^{π} = 6^{+} level at E_{x} = 15.16 MeV and the J^{π} = 8^{+} level at E_{x} = 18.54 MeV to the first excited state of ^{16}O was studied by (1992LA01). See 20.19 (in PDF or PS). For γdecay measurements see (1987FI01), 20.19 (in PDF or PS) and (1978AJ03). Resonant characteristics of statistical fluctuations in ^{12}C(^{12}C, α)^{20}Ne leading to the 12 lowest ^{20}Ne states were studied by (1993GA02). The yields of various groups of αparticles and their relevance to states of ^{24}Mg, and fusion cross sections, have been studied by many groups: see (1978AJ03, 1983AJ01, 1987AJ02). SubCoulomb cross sections calculated in a statistical framework are discussed in (1990KH05). A review of the state of theory and experiments on ^{12}C + ^{12}C reactions with formation of molecular states is presented in (1987DA1L). See also (1987ER1B, 1988GO1G, 1988DE18, 1991SZ02).
Angular distributions of the ^{6}Li ions to many states of ^{20}Ne below 17.5 MeV have been reported for E(^{14}N) = 30 to 78 MeV and E(^{12}C) = 67.2 MeV. At the latter energy ^{20}Ne*(16.67, 17.38, 18.11, 19.16, 19.6) are particularly strongly populated: see (1978AJ03). For reaction (b) to ^{20}Ne_{g.s.} see the angular correlation measurements at E(^{14}N) = 30  42 MeV reported by (1988AR24, 1994ZU03), and see the review of (1987GO12). An analysis of differential cross sections and angular correlation functions within a compound nuclear model is described in (1994BE55). Earlier work is cited in (1987AJ02). See also (1988BEYB, 1989BEXN, 1992ARZX).
Reaction (a) was studied at 150 MeV in a search for highspin αcluster resonances in ^{20}Ne. A broad 10^{+} resonance was located at 27.5 MeV (1988AL07). See also (1988CAZV, 1994RA04). Excitation functions in the range E_{cm} = 25.7  38.6 MeV were measured by (1993ES01). See also the comment (1993ZH21) and reply (1993ES03) on the work. Excitation functions for reaction (a) leading to members of the ^{20}Ne ground state rotational band were measured for E_{cm} = 22  29 MeV by (1995SU06). A triple coincidence measurement of reaction (b) through the ^{20}Ne 6^{+} level at E_{x} = 8.78 MeV was reported by (1989WUZZ). α  α coincidence measurements by (1994KU18) at E_{cm} = 26.9 MeV were used to study the connection of highly deformed isomeric states in ^{28}Si, ^{24}Mg and ^{20}Ne.
This reaction was studied with the use of molecular orbital theory (1988DI08).
For cross sections see (1986CU02).
See reaction 9.
For yields of 1.63 MeV γrays see (1982DE39).
Spectra were measured for E(^{20}Ne) = 150 MeV/nucleon (1992EGZZ).
Observed resonances in the yield of capture γrays over the range E_{α} = 0.8 to 10 MeV are displayed in 20.21 (in PDF or PS). For a discussion of ^{20}Ne*(11.26) [J^{π} = 1^{+}; T = 1], to which excitation by this reaction is parity forbidden, see (1983FI02). See also (1984BU01). Total cross sections have been measured in the range E_{cm} = 1.7 to 2.35 MeV. Assuming that S does not vary with energy over that interval, the astrophysical factor for nonresonant capture to ^{20}Ne_{g.s.} is 0.26 ± 0.07 MeV · b. An estimate of 0.7 ± 0.3 MeV · b for S at 300 keV is deduced (1987HA24). A comment (1988BA26) on this work summarizes the status of theoretical descriptions of ^{16}O(α, γ)^{20}Ne and discusses the (1987HA24) result in the light of a microscopic calculation. See also 20.21 (in PDF or PS). For other papers on astrophysical considerations see (1985CA41, 1988CA26, 1990BL1K, 1991RA1C). For earlier work, see (1987AJ02). A microscopic description of the α + ^{16}O system in a multicluster model is discussed in (1994DU09). An anharmonic oscillating model description is presented in (1993CSZU).
For reaction (a) see (1990KOZG). For reaction (b) see (1986KA36). A theoretical study of clustering in Yrast states is described in (1995KA53).
Excitation functions have been measured over a wide range of energies for elastically and inelastically scattered αparticles and γrays from the decay of ^{16}O*(6.13, 6.92, 7.13) [see (1978AJ03, 1983AJ01)] and (1986LE23; 1.8 to 4.8 MeV; α_{0}), (1985JA17; 2.0 to 3.6 MeV; α_{0}), (1983CA1F, 1985CA09; 9.2 to 13.5 MeV; α_{0}), (1992LA01; 10.2 to 18 MeV; α_{1}) and (1979BI10, 1984RI06; 14.6 to 20.4 MeV; α_{0} → α_{5}). See also (1983FR14, 1985ISZU) and ^{16}O in (1993TI07). A number of anomalies are observed: see 20.22 (in PDF or PS). K^{π} parameter assignments derived from this and other work are displayed in 20.20 (in PDF or PS) (1984RI07). See also (1983MI22, 1990WE14, 1992AR18). Backscattering cross section measurements and other applicationrelated studies are reported in (1990LE06, 1991LE33, 1992DE10, 1993CH48, 1993SO19). For reaction (b) see ^{12}C in (1985AJ01). In theoretical work related to ^{16}O(α, α)^{16}O, studies have been reported for: optical potentials in the range E_{α} = 0  150 MeV (1993AB02, 1995MI13), phase equivalent complex potentials (1996BA26), quadrupole resonances (1993BY03), a singlefolding potential model (1993LI25, 1993YA08), an Rmatrix analysis of elastic cross sections in the range E_{α} = 2  9 MeV (1994SH35), the orthogonality condition model (1987SA55), Yrast structure change of ^{20}Ne (1987KA24), microscopic cluster theory (1987TA1C), coreplusalpha states in terms of vibron models (1988CS01), distribution of αparticle strength (1988LE05), α cluster formation in the clusterorbital shell model (1990HA38), the microscopic complex effective interaction for α  ^{16}O (1991YA08), and the generatorcoordinate description (1987RE04, 1992KR12).
Deuteron groups have been observed to many states of ^{20}Ne: see 20.23 (in PDF or PS). Angular distributions have been measured for E(^{6}Li) = 5.5 to 75.4 MeV: see (1978AJ03, 1983AJ01, 1984MO08). Measurements of angular diestribution at E(^{6}Li) = 22 MeV provided data that were used to determine the ratios of αparticle widths in ^{19}Ne relative to ^{20}Ne (1995MA28) and to obtain alpha spectroscopic factors for ^{20}Ne states up to E_{x} = 6 MeV (1996MA07). Angular correlations [(d, α_{0}) to ^{16}O_{g.s.}] have been measured at E(^{6}Li) = 60, 75, and 95 MeV (1982AR20, 1988ARZU). An experimental study of the competition between evaporation and direct transfer is described in (1995XE01). See also references cited in (1987AJ02). In theoretical work published since the previous review, HauserFeshbach theory was applied to this reaction by (1987AR13), and angular distributions were analyzed with DWBA formalism by (1992RA22). See also (1994OS05).
States observed in this reaction are displayed in 20.23 (in PDF or PS). Angular distributions have been measured at E(^{7}Li) = 15 to 68 MeV: see (1978AJ03, 1983AJ01). See also (1986CO15). The reaction ^{7}Li(^{16}O, t)^{20}Ne was used in a lifetime measurement by (1995YU05). Theoretical work related to this reaction includes studies on: the form of the α particle potential in direct αtransfer reactions (1986GR29, 1988GR1I), a Hauser Feshbach theory application (1987AR13), the optical potential (1989BE51), clustering phenomena and shell effects (1988RA1G), DWBA analysis (1992RA22).
See (1985CU1A).
Angular distributions in reaction (a) have been measured for E(^{16}O) = 27.1 to 53.0 MeV and for E(^{12}C) = 22.7 to 78 MeV [see (1978AJ03, 1983AJ01)] as well as at E(^{12}C) = 109 MeV (1984MU04, 1985MU14; ^{20}Ne*(1.63, 4.25, 5.79, 7.16, 8.78, 10.26, 11.95, 12.59, 15.34, 15.87, 17.30, 21.08, 22.87); σ(θ) at several angles; EFRDWBA analysis). See also (1988CAZV). Γ_{α0}/Γ are displayed in 20.23 (in PDF or PS): see (1983AJ01, 1987AJ02) and (1983SH26). Spectroscopic factors were extracted in a direct reaction study reported by (1989OS02). Evidence for 10^{+} strength at E_{x} = 27.5 MeV is reported by (1988AL07). See also (1983DEZW). For discussion of ^{28}Si states reached in this reaction see (1993ES01, 1993ES03, 1993ZH21). See also the discussion of instrumentation development for ^{8}Be detection reported in (1991SU15). For reaction (b) see (1978AJ03) and (1986CA19). For reaction (c) and for a discussion of ^{24}Mg states reached in this reaction see (1983SH26, 1984MU04). See also (1985BE37, 1986BE19, 1987SU03).
At E(^{13}C) = 105 MeV angular distributions to ^{20}Ne*(1.63, 4.25, 8.78, 11.95, 15.34, 21.0) have been studied by (1979BR03): the first four states are the 2^{+}, 4^{+}, 6^{+}, and 8^{+} members of the 0^{+}_{1} band; the two higher states [J^{π} = 7^{}, 9^{}] belong to the 0^{} band for which the band head is ^{20}Ne*(5.79). In addition, distributions are reported to ^{20}Ne*(12.59, 15.9, 17.3) [J^{π} = 6^{+}, 8^{+}, 8^{+}] (1979BR03). See also (1985MU14). Spectroscopic factors were extracted in a direct reaction study reported by (1989OS02). For fusion cross sections see (1986PA10).
Angular distributions have been reported to a number of states of ^{20}Ne at E(^{16}O) = 23.9 to 95.2 MeV [see (1978AJ03, 1983AJ01)] and at E(^{16}O) = 26, 28, and 30 MeV (1986CA24). (1983ME13) have studied the quasielastic spectrum at E(^{16}O) = 50, 60, 68, and 72 MeV. Measurements of the energy dependence for E(^{16}O) = 51  66 MeV were performed by (1996FR09). For excitation functions see (1986CA24; ^{20}Ne*(0, 1.63)). See also (1982KO1C, 1984ME10, 1985ST1B, 1982KO1D, 1984AP03, 1984KO13). Studies of the directreaction mechanism for this reaction have been carried out by (1988GA1L, 1988GA19, 1989OS02, 1990OS03). See also (1988AU03) and references cited in (1987AJ02).
The excitation function for α_{0} shows a resonance corresponding to ^{20}Ne*(28.): see (1978AJ03). Measurements of A_{y} at E(^{3}He) = 33 MeV, have been reported for the elastic scattering [reaction (a)] (1983LE03) and for many αgroups [see ^{16}O in (1993TI07)] (1982KA12). For the earlier work and for other channels see (1983AJ01, 1987AJ02).
Neutron emission from this reaction was measured for E_{α} = 5.15 and 5.49 MeV by (1987SM09). Excitation functions were measured at astrophysical energies and Sfactor curves were determined by (1995KU1H). See also work cited in (1978AJ03). In a recent theoretical study, the threecluster generator coordinate method was applied to calculation of the low energy cross section by (1993DE32).
At E = 115 MeV the 8^{+} state at E_{x} = 11.95 MeV is strongly populated in both reactions: see (1983AJ01).
Angular distributions have been measured for E(^{3}He) = 2.8 to 18.3 MeV. States of ^{20}Ne observed in this reaction are displayed in 20.23 (in PDF or PS) of (1983AJ01). These include a state at E_{x} = 16.7329 ± 0.0027 MeV, Γ_{cm} = 2.0 ± 0.5 keV: J^{π} = 0^{+}, T = 2. Differential cross sections were measured at E(^{3}He) = 30 MeV by (1995FUZT).
The previous review (1987AJ02), observed that over the range E_{p} = 2.9 to 12.8 MeV, the γ_{0} and γ_{1} yields are dominated by the E1 giant resonance (Γ ≈ 6 MeV) with the γ_{1} giant resonance displaced upward in energy. Strong wellcorrelated structures are observed with characteristic widths Γ ≈ 175 keV. Angular distributions taken over the energy range do not vary greatly with energy. They are incompatible with γ_{0} and γ_{1} coming from the same levels in ^{20}Ne. The 90° γ_{0} yield for E_{p} = 3.5 to 10 MeV has been measured: the results are interpreted in terms of four primary doorway states at E_{x} = 16.7, 17.8, 19.1 and 20.2 MeV. See also (1985WAZV; E_{p} = 5.9 to 10.3 MeV; E2 strength; prelim.). See also (1986OUZZ). More recently, polarized and unpolarized angular distributions were measured for E_{p} = 16.1  23.0 MeV (1988KU08). Data for (p, γ_{1}) were also presented and a doorway state calculation was discussed. Cross section and analyzing powers for (p, γ_{0}γ_{1}) were measured in the range E_{p} = 3.5  13.3 MeV by (1988WA13) in a study of the E2 strength in ^{20}Ne. See also the review of giant resonance work in (1988HA12). The yield curve for 11.2 MeV γrays [from the decay of ^{20}Ne*(11.26), J^{π} = 1^{+}, T = 1, to the ground state] displays a resonance at E_{p} = 4.090 ± 0.005 MeV [^{20}Ne*(16.73)]. The 11.2 MeV γrays are isotropic which is consistent with the presumed 0^{+} character of this lowest T = 2 state in ^{20}Ne: Γ_{p}Γ_{γ}/Γ ≈ 0.5 eV. Since Γ_{p}/Γ (from the elastic scattering) is ≈ 0.1, Γ_{γ} ≈ 5 eV. For E_{p} = 5.65 to 6.21 MeV, the γ_{0} and γ_{1} yields are not resonant but the yield of 10.6 MeV γrays is resonant at 5.879 ± 0.007 MeV [Γ_{cm} = 9.5 ± 3 keV, Γ_{p0}Γ_{γ}/Γ ≈ 0.05 eV; Γ_{γ} ≈ 0.3 eV]. The 10.6 MeV γray is due to the cascade decay of ^{20}Ne*(18.43), J^{π} = 2^{+}, T = 2 via ^{20}Ne*(12.22) to the 2^{+} state at 1.63 MeV. For the upper limits to the strengths of the transitions to various states of ^{20}Ne from the 0^{+} and 2^{+} T = 2 states, see (1983AJ01). Internal pair conversion of the GDR at E_{x} ≈ 18 MeV was observed by (1989MOZY). Resonances observed in the capture reaction are displayed in 20.24 (in PDF or PS). For references see (1978AJ03, 1983AJ01). See also the astrophysicsrelated work in (1987RO25, 1988CA26). A study of absolute thicktarget yields for elemental analysis at E_{p} = 7, 9 MeV is reported in (1987RA23).
The elastic scattering has been studied in the range E_{p} = 0.5 to 7.5 MeV and 24.9 to 46.3 MeV [see (1978AJ03)] and at E_{p} = 1.5 to 3.5 MeV (1985OU01, 1986OUZZ, 1986OU01). See also the measurements for E_{p} = 0.85  1.01 MeV at θ_{ lab} = 165° by (1989KN01), and the work reported in (1994CO12) in which a ^{19}F radioactive beam was used in scattering off polyethelyne targets. The observed anomalies are displayed in 20.25 (in PDF or PS). Resonances for inelastic scattering [p_{1} and p_{2}] are listed in 20.26 (in PDF or PS). In general the resonances observed are identical with those reported from other ^{19}F + p reactions, although the relative intensities differ greatly. Cross sections for production of 110 and 197 keV γrays are reported for E_{p} = 0.5 to 4.3 MeV by (1986CHYY). See also (1983LE28; astrophysics) and (1986BA88). For reaction (b) see (1986KA1U; applied) and ^{18}F.
Observed resonances are displayed in 20.30 (in PDF or PS) of (1978AJ03). See also (1984BA1R, 1985CA41). The transfer polarization coefficient for E_{p} = 120, 160 MeV at θ = 0° was measured by (1990HUZY). Total cross sections for production of ^{19}Ne measured by the activation method are reported by (1990WA10).
Many resonances occur in this reaction. They are displayed in 20.27 (in PDF or PS), 20.29 (in PDF or PS), and 20.28 (in PDF or PS) depending on whether they are observed in the α_{0} yield [20.23], in the α_{1} [or α_{π}] yield to ^{16}O*(6.05) [20.24] or in the α_{2}, α_{3}, and α_{4} yields [or in the yield of the γrays from ^{16}O*(6.13, 6.92, 7.12) [20.25]]. See also Tables 2 and 3 in (1993DA23) which list a number of new resonances for E_{p} = 0.3  3.0 MeV. Resonances for α_{0} and α_{1} are required to have even J, even π or odd J, odd π, while the α_{2}, α_{3}, and α_{4} resonances are all oddeven or evenodd, with the exception of the T = 2 resonance. Listings of the earlier yield studies are given in (1972AJ02, 1978AJ03, 1983AJ01). A detailed discussion of the evidence leading to many of the J^{π} assignments is given in (1959AJ76). For values of θ^{2} see 20.28 (in PDF or PS) in (1978AJ03). Other measurements are reported by (1985OU01; 1.5 to 2.1 MeV; α_{0} → α_{3}) and (1984IN04; 4.15 to 13 MeV; α_{0} → α_{5}). In the latter work there are no marked correlations between the different channels. Longitudinally and transversely polarized protons with E_{p} ≈ 0.67 MeV have been used to study ^{20}Ne*(13.48) [J^{π} = 1^{+}; T = 1] via a parity (and isospin) forbidden αtransition. The state is not excited. The upper limits for the process, and their significance in the determination of f_{π}, the weak pionnucleon coupling constant, are discussed by (1983KN01, 1986KN1C, 1990KN01). See also (1983AJ01, 1984KN1A). Internal pair conversion for ^{19}F(p, α_{π}) of the 18 MeV GDR in ^{20}Ne was studied by (1989MOZY) at E_{p} = 5.2 MeV. A DWBA analysis for energies below the Coulomb barrier is used to determine the astrophysical Sfactor in (1991HE16). See also (1993YA18). Applicationrelated work is reported in (1987EV01, 1989MC04, 1989MC03, 1989TA1N). See also the earlier work cited in (1987AJ02).
Levels of ^{20}Ne derived from this reaction are displayed in 20.31 (in PDF or PS) in (1972AJ02) and 20.34 (in PDF or PS) in (1978AJ03). See also (1983LIZW).
Levels of ^{20}Ne observed in this reaction are displayed in 20.35 (in PDF or PS) in (1978AJ03) and 20.32 (in PDF or PS) in (1983AJ01). Deuteron angular distributions have been studied at E(^{3}He) = 9.5 to 21 MeV: see (1978AJ03). A more recent measurement of differential cross sections at E(^{3}He) = 22.3 MeV and DWBA analysis was reported by (1994ARZY). The excitation energy difference (ΔE_{x}) between the 1^{+} and 1^{}, T = 1 states ^{20}Ne*(11.26, 11.27) is 11.1 ± 0.7 keV (1983FI02). Γ_{γ}/Γ_{α} = 0.88 ± 0.05 for ^{20}Ne*(12.22) [2^{+}; T = 1] (1984CA08). Using (2J + 1)Γ_{α}Γ_{γ}/Γ = 1.41 ± 0.23 eV (1980FI01), Γ_{α} = 0.32 ± 0.06 eV for ^{20}Ne*(12.22) (1984CA08). The value of Γ_{γ}/Γ of ^{20}Ne*(12.22) implies B(M1) = 0.07 W.u. for the transition from ^{20}Ne*(18.43) [2^{+}; T = 2]. This is much weaker than other isovector M1 transitions in ^{20}Ne and a factor of five lower than predicted by shell model calculations: see (1984CA08). In recent work at E(^{3}He) = 25 MeV, differential cross sections were measured (1994VE04) for ^{20}Ne levels at E_{x} = 0, 1.634 MeV. DWBA calculations were carried out and absolute values of C^{2}S were extracted and compared with shell model calculations.
Angular distributions have been measured at E_{α} = 18.5 and 28.5 MeV: see (1978AJ03, 1983AJ01). The double differential cross section was measured at E_{α} = 30.3 MeV in a study of the reaction mechanism involving excitation of the 0^{+}, 2^{+} and 4^{+} states at E_{x} = 0, 1.63, 4.25 MeV (1995IG03).
Angular distributions have been studied at E(^{7}Li) = 34 MeV to a number of states of ^{20}Ne. C^{2}S values are consistent with those reported in the (d, n) and (^{3}He, d) reactions: see (1978AJ03).
The decay is primarily to ^{20}Ne*(1.63) with a halflife of 11.163 ± 0.008 s (1992WA04): see reaction 1 in ^{20}F. Besides the principal decay to ^{20}Ne*(1.63) [log f_{0}t = 4.97], ^{20}F also decays to ^{20}Ne*(4.97) [J^{π} = 2^{}] with a branching ratio of (0.0082 ± 0.0006)% (1987AL06) [log f_{0}t = 7.20 ± 0.03; D.E.Alburger and E.K.Warburton, see (1987AJ02)]. The upper limit for the groundstate decay is 0.001% [log f_{0}t > 10.5]. For other values and earlier references see 20.36 (in PDF or PS) in (1978AJ03). The energy of the γray from ^{20}Ne*(1.63) is 1633.602 ± 0.015 keV. E_{γ} for the 4.97 → 1.63 transition is 3332.54 ± 0.19 keV which gives E_{x} = 4966.51 ± 0.20 keV based on E_{x} = 1633.674 ± 0.015 keV for the first excited state. The shape of the βspectrum is in good agreement with the predictions of CVC (1983AJ01, 1987AJ02, 1989HE11). βγ angular correlations reported by (1988RO10) are close to the expectations based on CVC theory. For earlier work see (1978AJ03, 1983AJ01, 1987AJ02). The ^{20}F(β^{})^{20}Ne decay is thought to play a part in heavy element nucleosynthesis (1988AP1A). See also (1989MA1U, 1989TA26).
The photoneutron cross section (bremsstrahlung photons) shows peaks at E_{x} = 17.78 ± 0.05, 19.00 ± 0.05, 20.15 ± 0.15 [main peak of the GDR], 22.6 ± 0.3, 24.9 ± 0.5 and 27.5 MeV [the latter three states are broad]: the integrated cross section to 28.5 MeV is 58 ± 6 MeV · mb [exhausting ≈ 20% of the dipole sum]. The cross section for (γ, tot) using monoenergetic photons shows a structure at 18 MeV and some fluctuations atop the broad giant dipole resonance, σ_{max} ≈ 7 mb. The double photoneutron cross section, σ(γ, 2n), is dominated by a single peak at E_{γ} ≈ 20.5 MeV, σ_{max} ≈ 1.1 mb. For references see (1978AJ03, 1983AJ01) and see the atlas of photoneutron cross sections with monoenergetic photons (1988DI02). The significance of reaction (c) to astrophysics is discussed by (1982SA1A, 1984FO1A).
The first 1^{+}; T = 1 state in ^{20}Ne is measured at E_{x} = 11262.3 ± 1.9 keV. The branchings to ^{20}Ne*(0, 1.63) are (84 ± 5) and (16 ± 5)%, respectively (1983BE19). See also (1984BE26).
The ^{20}Ne charge radius, < r^{2} >_{1/2} = 3.004 ± 0.025 fm. Form factors for many excited states of ^{20}Ne with E_{x} < 8 MeV have been reported: see (1978AJ03). At E_{e} = 39 and 56 MeV, the 180° inelastic scattering is dominated by the transition to a J^{π} = 1^{+}, T = 1 state at E_{x} = 11.22 ± 0.05 MeV with Γ_{γ0} = 11.2^{+2.1}_{1.8} eV. A subsidiary peak is observed corresponding to a state 0.35 ± 0.03 MeV higher [if J^{π} = 1^{+} or 2^{+}, Γ_{γ0} = 0.65 ± 0.18 or 0.40 ± 0.13 eV]. A number of small peaks are also reported corresponding to E_{x} ≈ 12.0, 12.9, 13.9, 15.8, 16.9, 18.0 and 19.0 MeV. Prominent electric dipole peaks are reported at E_{x} = 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 E_{x} = 13.0, 13.7, 14.5, 15.0, 15.4 and 16.2 MeV and there is broad quadrupole excitation between 16 and 25 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 11 < E_{x} < 24 MeV only two isovector M2 transitions appear: these are to ^{20}Ne*(11.62, 12.10) with B(M2, k)(↑) = 64 ± 13 and 56 ± 13 μ^{2}_{N}fm^{2} [orbital contributions are nonnegligible]. The M1 transition to ^{20}Ne*(11.26) is also observed but that to ^{20}Ne*(13.48) is not: it is < 0.2 μ^{2}_{N} (1985RA08). For reaction (b) see (1978AJ03). Reaction (c) has been studied in order to obtain the (γ, α_{0}) cross section in the giant resonance region: the cross section at 90° for E_{x} = 15 to 24 MeV is dominated by an E1 resonance [1^{}; T = 1, with an admixture of T = 0 which permits the α_{0} decay] at E_{x} = 20 MeV; lesser E1 structures are reported at E_{x} = 16.7, 17.1, 21 and 22 MeV. A relatively strong 2^{+}; T = 0 resonance appears at E_{x} = 18.5 MeV, and evidence is reported for increasing E2 strength below 16 MeV. For references to the early work see (1978AJ03, 1987AJ02). For more recent work see the reviews on nuclear dipole excitations (1987BE1G) and status of the shell model (1988BR1P). Other more recent theoretical work includes studies of large basis space effects in electron scattering form factors (1990AM01), correlated charge form factors and densities for sd shell nuclei (1990MA63), electron scattering multipoles for symplectic shell model application (1992RO08), mass number dependence of the difference between electron and muonscattering charge radii (1989AN12), electron scattering from ^{20}Ne in a microscopic boson model (1988KU07, 1988KU22, 1988KU17), and studies of (e, e'γ) reactions and electromagnetic currents in rotational nuclei (1990GA09). See also (1988BR1D, 1988ZH1F, 1990MO1J).
Inelastic pion scattering experiments at T_{π} = 120 MeV and 180 MeV indicate a broad 2^{+} member of the K^{π} = 0^{+}_{4} band in ^{20}Ne (1989BU14, 1995BU01). They report E_{x} = 9.00 ± 0.18 MeV, Γ = 0.8 MeV, B(E2(↑)) = 40.9 ± 2.0 e^{2}fm^{4}. Several other states in the first four K^{π} = 0^{+} bands were studied by (1995BU01). See 20.30 (in PDF or PS). For reaction (b), spectra have been measured and analyzed for initial pion momenta of 6.2 GeV/c (1991AM1B, 1992KI31).
An evaluation of neutroninduced reaction cross sections of ^{20}Ne for E_{n} = 1  30 MeV is presented in (1991RE10). See also (1993DE32) and earlier work cited in (1978AJ03).
Angular distributions of elastically scattered protons and of a number of inelastic groups have been measured for E_{p} = 2.15 to 65 MeV [see (1978AJ03, 1983AJ01)] and at E_{p} = 0.8 GeV (1984BL14, 1988BL13; to ^{20}Ne*(0, 1.63, 4.25, 8.7) (u); also A_{y}). The latter work confirms the large hexadecapole deformation of ^{20}Ne. At E_{p} = 201 MeV, probable 1^{+} states at E_{x} = 11.25 ± 0.01, 13.51 ± 0.03 and 15.72 ± 0.05 MeV are reported by (1987WI03): There does not appear to be any quenching of the M1 strength. In addition 2^{} states are observed at 11.58 and 12.08 MeV with B(M2) = 64 ± 13 and 56 ± 13 μ^{2}_{N} as is a state of unknown J^{π} at E_{x} ≈ 17 MeV (1987WI03). See also (1988CR1B), the measurements at E_{p} = 6.4  7.7 MeV (1992WI13), measurements at E_{p} = 60  180 MeV (1993PLZY), and the earlier work cited in (1978AJ03). For reaction (b) see (1984CA09, E_{p} = 101.5 MeV), (1992WI13, E_{p} = 6.4  7.7 MeV), and the earlier experimental and theoretical work cited in (1987AJ02). See also (1993MU28). Theoretical work reported since the previous compilation includes relativistic DWBA calculations on inelastic scattering at E_{p} = 200  800 MeV (1988JO02), a largebasisspace microscopicmodel analysis of 800MeV inelastic scattering (1991AM1A), studies with a coalescence model of hypernuclear formation and mesonic atom production (1989WA14) in high energy collisions (1988WA16, 1989SA58), analysis of 800MeV inelastic scattering with the Dirac formalism (1990PH01, 1990PH02, 1992DE31). See also the microscopic threecluster study of 21nucleon systems presented in (1993DE32).
Experimental data on multiplicity, correlations, and inclusive spectra of mesons and other particles produced in p + ^{20}Ne reactions at E_{p} = 300 GeV are presented in (1992YU1A) and compared with model predictions.
For references to work on antiproton interactions see 20.16 (in PDF or PS) and "GENERAL section" here.
Angular distributions of deuterons have been reported at E_{d} = 10.0 to 52 MeV [see (1978AJ03, 1983AJ01)] and at E_{d} = 52 MeV (1987NU01). Differential cross sections for elastic and inelastic scattering of tritons (reaction (b)) were measured at E_{t} = 33.4 MeV by (1992HA12) and analyzed by the coupled channels method. Potential parameters, deformation lengths and multipole moments were deduced. See also the calculations for these data described in (1992HA18) in which spin, parity and band assignments are discussed. The calculations suggest the assignments of K^{π} = 2^{}, 2^{} and 0^{} respectively to the J^{π} = 2^{}, 3^{}, 3^{} states at E_{x} = 4.97, 5.62 and 5.79 MeV. See also (1978AJ03, 1987AJ02).
Angular distributions have been measured at E(^{3}He) = 10 to 35 MeV and at 68 MeV: see (1978AJ03). See references cited in (1978AJ03). More recently differential cross section for elastic and inelastic scattering of ^{3}He were measured at E(^{3}He) = 33.4 MeV by (1992HA12) and analyzed by the coupled channels method. Comparisons were made with triton scattering. Calculations for these data were described in (1992HA18) in which spin, parity and band assignments are discussed. Elastic scattering measurements at E(^{3}He) = 30 and 45 MeV are described in (1992NAZQ).
Angular distributions have been measured at E_{α} = 3.8  155 MeV [see references cited in (1978AJ03)]. More recently measurements were made at E_{α} = 54.1 MeV (1987AB03), E_{α} = 50 MeV (1991FR02) and at E_{α} = 3.8  11 MeV (1991AB05). Inelastic cross sections were measured at E_{α} = 5.6  11.0 MeV (1992DA10), E_{α} = 50 MeV (1991FR02), and E_{α} = 50.5 MeV (1987BU27). For reaction (b) see references cited in (1983AJ01, 1987AJ02) and the measurements at E_{α} = 155 MeV of cross sections and decay branching ratios for several excited states of ^{20}Ne up to the giant quadrupole resonance by (1987SU09). Theoretical studies related to these reactions include: α + ^{20}Ne structures of ^{24}Mg in a microscopic threecluster (α + α + ^{16}O) model (1987DE40), distributions of αparticle strengths in light nuclei (1988LE05), target clustering and exchange effects in internuclear interactions (1988LE06), stationarystate currents in nuclear reactions (1988MA30), a DWIA analysis of ^{20}Ne(α, 2α)^{16}O at E_{α} = 140 MeV (1988SH05), distortion effects in a microscopic ^{16}O + 2α description of ^{24}Mg (1989DE32), evidence for a parity dependence in the α + ^{20}Ne interactions (1989MI12), an ldependent representation of a Majorana potential (1990CO38), a strongabsorption model analysis of α scattering (1992RA21), a calculation of quasimolecular states in ^{20}Ne(α, α) (1992GR15), optical model analysis of ^{20}Ne(α, α) at E_{α} = 22.9 MeV (1993AOZZ).
Angular distributions have been studied at E(^{7}Li) = 36, 68, and 89 MeV: see (1983AJ01).
For pion production see (1985FR13).
Elastic angular distributions have been measured at E(^{10}B) = 65.9 and E(^{11}B) = 115 MeV: see (1983AJ01).
Elastic angular distributions have been obtained at E(^{12}C) = 22.2 to 77.4 MeV and at E(^{20}Ne) = 65.9, 74 and 75.2 MeV [see (1978AJ03, 1983AJ01)] as well as at E(^{20}Ne) = 72.6, 74.0 and 75.2 MeV (1982SH29). Elastic and inelastic scattering differential cross sections at E(^{20}Ne) = 390 MeV were measured by (1993BO28). For yield, fusion, total reaction cross section and fragmentation studies see the references cited in (1987AJ02). More recently fragmentation studies at E(^{20}Ne) = 540  1096 MeV/nucleon were reported by (1990WE14) and at E(^{20}Ne) = 400, 800 MeV/nucleon by (1988DU01). See also (1987AN20, 1994FU01). For pion production and for reaction (b) see references cited in (1987AJ02). Theoretical studies carried out since the previous compilation include: resonances, heavyion radioactivity and new predictions for medium mass collective systems (1989CI1C), cascade model study of Λ particle productions in central collisions of light nuclei (1988IW02), comparison of quantized ATDHF and GCM theory applied to the ^{12}C + ^{20}Ne system (1990SL01).
Angular distributions have been studied at E(^{20}Ne) = 50 and 94.8 MeV involving ^{16}O_{g.s.} and ^{20}Ne*(0, 1.63, 4.25) [see (1983AJ01)], at E(^{16}O) = 25.6 to 44.5 MeV (elastic; also to ^{20}Ne*(1.63) at 31.3, 33.3 and 44.5 MeV)) and at E(^{20}Ne) = 66.8, 115, 137 and 156 MeV (elastic) [see (1987AJ02) for references]. Yield and fusion cross section measurements have also been reported in several references cited in (1987AJ02). Excitation functions at θ_{cm} = 90° for E_{cm} = 21.5  31.2 MeV were measured by (1988HE06) and at θ_{lab} = 13° for E_{cm} = 22.8 to 38.6 MeV by (1989SA14). Measurements at projectile energies of 3.6 MeV/nucleon are reported in (1987AN20), and at 4.2 and 4.5 GeV/nucleon by (1988BO46, 1988BE2A). Theoretical studies related to this reaction reported since the previous review include: calculation within the framework of the cascade model (1988IW02), molecular orbital theory for elastic and inelastic scattering (1989HE1I), derivation of the parityindependent interaction for ^{16}O + ^{20}Ne (1989GA1L), optical model analysis of resonant structure in ^{16}O + ^{20}Ne (1991GA14), and local representation of a deep parity and Ldependent ^{16}O + ^{20}Ne potential (1993AI02).
Elastic angular distributions are reported at E(^{20}Ne) = 68, 117, 140, and 156 MeV (1983SH25). For yield and fusion measurements see references cited in (1983AJ01, 1987AJ02). Highspin shape isomers for sdshell nuclei were studied at E_{cm} near 1.6 times the Coulomb barrier for ^{20}Ne + ^{20}Ne by (1993BAZZ). Studies of the average number of interacting protons in ^{20}Ne + ^{20}Ne collisions of 36 GeV/nucleon were reported by (1987AN20). Theoretical work related to the reaction includes: a study of mesonic atom production by a coalescence model (1989WA14), a formulation of the mesonic atom production probability with a coalescence model (1989SA58), hypernucleus production by heavy ions by a coalescence process (1989BA92, 1989WA14, 1989BA93).
Elastic angular distributions for reaction (a) have been measured at E(^{20}Ne) = 50, 60, 80, 90, and 100 MeV [see (1983AJ01)] at 40 MeV (1983NA04; S_{α} for the system ^{20}Ne + ^{24}Mg = 0.08 ± 0.02) and at E_{lab} = 55, 80 and 160 MeV/nucleon (1987BE38). For yield and fusion cross sections for reactions (a) and (b) see references cited in (1987AJ02). See also the review of high energy gamma production in heavy ion collisions (1989NI1D).
Elastic angular distributions are reported at E(^{20}Ne) = 55.7, 63, 125, and 151 MeV (1983NG01). For yield, fusion and evaporation residue studies see references cited in (1987AJ02) and the study at E(^{20}Ne) = 217, 194 and 384 MeV (1988GR12, 1989BA17, 1990BA18). A search for incomplete deep inelastic collisions at E(^{20}Ne) = 216 MeV is reported by (1988ZH12). Neutral pion production was studied at E(^{20}Ne) = 4 GeV by (1988JU02, 1989FO07, 1989FO1G). A description of those data by the cooperative model is discussed in (1989GH01). See also the calculation of total reaction cross sections presented in (1988JO02).
See (1983DU13).
Angular distributions have been studied at E(^{20}Ne) = 44.1 to 70.4 MeV and at 151 MeV: see (1983AJ01). For an evaporation residue study see (1982MO15). For yield and fusion measurements see (1983AJ01). The breakup of ^{20}Ne at E(^{20}Ne) = 92, 149 and 213 MeV involves ^{20}Ne*(5.79, 6.73, 7.16, 8.78, 10.26, 11.95) (1986SH30). See also the references cited in (1987AJ02) and see the Monte Carlo simulation method calculation for nuclear transfer (1988CH28), and the study of alpha clustering and shell effects related to this reaction (1989PU1C).
^{20}Na has a halflife of 447.9 ± 2.3 ms: see reaction 1 in ^{20}Na. It decays to a number of states of ^{20}Ne, principally ^{20}Ne*(1.63): see 20.31 (in PDF or PS). The ratio of the mirror decays ^{20}Na(β^{+})^{20}Ne*(1.63) and ^{20}F(β^{})^{20}Ne*(1.63), (ft)^{+}/(ft)^{} = 1.03 ± 0.02. β  γ correlation measurements, as in the decay of ^{20}F, lead to an upper limit for the secondclass contribution to the correlation which is consistent with zero: see (1983AJ01). A more recent measurement (1988RO10) concluded that the β  γ angular correlations in A = 20 are close to and may be in agreement with conserved vector current theory. β  ν  α triple correlation coefficient measurements for the transitions via the αunstable 2^{+} states shown in 20.31 (in PDF or PS) lead to values of the isospin mixing amplitudes [and to a determination of the vector weak coupling constant] (1983CL01, 1989CL02). See also references cited in (1987AJ02) and the measurements of (1992KUZO, 1992KUZQ).
A general expression of the polarized spectral function for the (e, e'n) transitions is used by (1994CA27) to model this reaction.
See (1978AJ03).
The T = 1 states observed in this reaction, and the analog states observed in ^{20}F in the (d, ^{3}He) reaction, are displayed in 20.16 (in PDF or PS of (1978AJ03). T = 0 states are presented in 20.38 (in PDF or PS) of 1978AJ03).
Angular distributions have been reported at E_{p} = 26.9 to 43.7 MeV: see (1978AJ03, 1983AJ01). The angular distributions of the tritons to the ground state of ^{20}Ne and to the first 0^{+}, T = 2 state [E_{x} = 16.7329 ± 0.0027 MeV] have been fitted by L = 0 and the tritons to ^{20}Ne*(18.4) by L = 2. The latter is the first 2^{+}, T = 2 state. The 0^{+}, T = 2 state [^{20}Ne*(16.73)] decays by α_{0}[(6 ± 5)%], α_{1} + α_{2}[(35 ± 12)%], α_{3} + α_{4}[(29 ± 12)%], p_{0+} p_{1+} p_{2}[(14 ± 9)%] and p_{3+} p_{4+} p_{5}[(13 ± 8)%] [measured branching ratios in percent are given in the brackets] to the final states in ^{16}O and ^{19}F. See (1978AJ03) for references and additional information.
Angular distributions have been measured at E_{p} = 10.0 and 45.5 MeV: see (1972AJ02). High resolution measurement at E_{p} = 1.08  4.15 MeV were carried out in a study of 94 resonances in ^{24}Mg by (1987VA24) at E_{p} = 6.25  6.55 MeV. A study of ^{24}Mg resonances excited by protons in the range E_{p} = 6.25  6.55 MeV is described in (1990MI24, 1991MI24). Detailedbalance tests of time reversal invariance are reported in (1994DR01, 1993MI19, 1993MI25). Parity nonconservation experiments are discussed in (1995MI28). See also (1987PA06, 1989KA06) which describe analyzing power measurements for this reaction. Measurements of the cross section at E_{p} ≤ 350 keV were carried out by (1989GO1N). Astrophysical implications are discussed. See also references to earlier work cited in (1987AJ02).
See (1978AJ03).
Cross sections for this reaction were calculated by (1987KA30) in a study of molecular structure of highlyexcited states.
Production cross sections for ^{20}Ne were measured at E_{n} = 5.20, 7.00, 16.20 and 19.05 MeV (1990LA09). Cross sections were calculated with preequilibrium emission and constanttemperature evaporation models by (1993KH09).
See (1984CA09). See also 1978AJ03).
Angular distributions have been studied to many states of ^{20}Ne at E_{d} = 28 to 80 MeV [see (1978AJ03, 1983AJ01)] and at E_{d} = 54.2 MeV (1984UM04; to ^{20}Ne*(0, 1.63, 4.25, 5.62)). 20.35 (in PDF or PS) in (1983AJ01) displays the observed states and S_{α} obtained from several analyses. For newer values of S_{α} see (1984UM04, 1986OE01). See also (1984PA18, 1986PAZJ). Measurements at several different incident energies were reported by (1988RA27, 1988RA20). Data were analyzed with finiterange DWBA calculations, and spectroscopic factors were obtained with different potentials. Comparisons with spectroscopic factors from ^{24}Mg(^{3}He, ^{7}Be)^{20}Ne were made.
Angular distributions have been studied at E(^{3}He) = 25.5 and 70 MeV: see (1978AJ03). See also (1983AJ01) and (1986RA15). Measurements at E(^{3}He) = 41 MeV were reported by (1988RA20, 1988RA27). Data were analyzed with finiterange DWBA calculations and spectroscopic factors were obtained with different potentials. Comparisons with spectroscopic factors from ^{24}Mg(d, ^{6}Li)^{20}Ne were made.
See (1983AJ01).
The angular distribution for the ground state transition has been measured at E(^{12}C) = 40 MeV (1982LI16) and at E_{cm} = 25.2 MeV (1990LE12). Coupledchannels calculations were used to study the back angle anomaly. The backward angle yield in the inverse reaction was studied at E(^{24}Mg) = 90  126 MeV by (1990GL01). See also (1983AJ01, 1989OB1C).
Excitation functions were measured at θ_{cm} = 90°, E_{cm} = 25  34 MeV by (1989LE19). Data were compared with calculations involving the coupling to higher orders between elastic and αtransfer channels. Differential cross sections were measured at E(^{16}O) = 71.4 MeV by (1995FUZW). The effect of the dynamic αtransfer polarization potential is discussed in (1989FI03).
See (1983AJ01).
This reaction was studied at E_{cm} = 31.57 MeV by (1989PO1J).
