S.I. Hayakawa

A comparative study of the 13C(p, p′)13C and 13C(p, n)13N reactions at Ep = 35 MeV☆

Abstract Differential cross sections were measured at Ep = 35 MeV for the 13C(p, n) and 13C(p, p′) reactions leading to the four low-lying states in the mirror nuclei 13N and 13C. In addition, the analyzing powers were measured for the 13C(p, p′) reaction. The data are generally well accounted for by DWBA calculations except for the 13 C(p, p′) 13 C (3.09 MeV , 1 2 + ) reaction, for which the calculations cannot even reproduce the qualitative features of the data. A comparison of the (p, n) and the (p, p′) results suggests that the isoscalar part of the 13 C ( g.s. , 1 2 − ) → 13 C (3.09 MeV , 1 2 + ) transition is not correctly described by currently available shell-model wave functions.

Structure of 14c studied by the 14c(p,d)13c reaction

Abstract Cross sections for the neutron pickup reaction 14 C(p, d) 13 C were measured at E p = 35.0 MeV for the states below E = 10 MeV, and at E p = 40.1 MeV for the states between E x = 11 and 18 MeV. Obtained angular distributions were compared with exact finite-range DWBA calculations to extract spectroscopic factors. Second-order DWBA calculations were also made in some cases. Almost full 0p 1 2 strength was found, while the observed 0p 3 2 strength was 80% of the simple sum-rule limit. The main part of the remaining strength was found in the 0d 5 2 orbit, and, in a lesser degree, in the 1s 1 2 and 0d 3 2 orbits. Small fractions of the 0f 5 2 and Og 9 2 strengths were also necessary to explain the angular-distribution shapes and the cross-section magnitudes of the predominantly multistep transitions to the 5− 2 and 5+ 2 states.

Hexadecapole strength in the region of the low-energy octupole resonance in 90Zr

Abstract The level structure of 90 Zr has been studied in the region of the low-energy octupole resonance ( E x = 5−9 MeV) by inelastic scattering of 65 MeV protons. The spectra were found to be highly structured; many states with different multi-polarities are excited. A large number of L = 4 states were found exhausting 5.8% of the E4 energy weighted sum rule.

M1 states in 58Ni observed by proton inelastic scattering at 65 MeV

Abstract Inelastic proton scattering at 65 MeV was used to study 1 + states in 58 Ni. A new 1 + state was found at an excitation of 5.166 MeV. The angular distributions for the 1 + states at 2.903 and 5.166 MeV were well reproduced by a DWBA calculation under the assumptions of pure v( p 3 2 f 5 2 ) and v( p 3 2 p 1 2 ) configurations, respectively. The angular distribution for the previously suggested 1 + state at 7.721 MeV was not well discribed by the DWBA calculation with the isoscalar ( f 7 2 −1 f 5 2 ) wave function. The shape of the angular distribution for the 10.672 MeV, 1 + state was well reproduced by the DWBA calculation with the isovector ( f 7 2 −1 f 5 2 ) wave function.

Neutron particle-hole multiplet states in 90Zr studied by proton inelastic scattering

Abstract The ν(g9/2)−1(d5/2) multiplet states in 90Zr have been identified using proton inelastic scattering at 65 MeV. The measured angular distributions were compared with microscopic DWBA calculations using simple shell-model wave functions. Remarkable agreement has been obtained for all the unnatural parity states of Jπ = 3+, 5+ and 7+.

Population of 6− and 5− states in 26Al by the (α, d) reaction

Abstract A number of 6 − and 5 − states in 26 Al were studied in the region of excitation energy 5–15 MeV with the 24 Mg(α, d) 26 Al reaction at E α = 63.7 MeV. The data were analyzed within the framework of zero-range DWBA theory for a macroscopic deuteron-cluster transfer as well as for a microscopic two-nucleon transfer, and compared with our previous results on the 25 Mg( 3 He, d) 26 Al reaction. Several 6 − and 5 − states are newly proposed. Five 6 − states previously assigned as T = 1 were weakly observed in the present (α, d) reaction, which should excite only T = 0 states. The isospin breaking (α, d) transition to the 6 − 1 , T = 1 state was found to be an order of magnitude larger than a second-order exact-finite-range DWBA calculation for the successive transfer processes of ( α - 3 He-d) and ( α -t-d).

The 16O(p,p′) reaction at 35 MeV

Abstract The 16O( p , p ′ ) reaction was studied with a 35 MeV polarized proton beam. The cross sections and analyzing powers for excited states in 16O up to and including the 2−, T = 1 state at 12.97 MeV were measured and compared with DWBA calculations. Both density-independent and densitydependent effective interactions were used in the calculations. Transition densities calculated using shell-model amplitudes and Woods-Saxon single-particle wave functions give poor accounts of the data. The use of macroscopic transition densities obtained from electron scattering data give a much better description of the data, especially when used in combination with the densitydependent interaction.

Excitation of spin- and isospin-flip states with the (d, ds=0) reaction*

The (d, d s =0 ) reaction has been studied for the first time at E d = 56 MeV and 70 MeV. It is demonstrated that the reaction is a useful tool for the study of the inelastic excitation of the spin- and isospin-flip mode. Several states in 12 C with T = 1 and S = 1 are strongly excited. The differential cross sections and vector analyzing powers are reasonably reproduced by the distorted-wave Born-approximation calculation.

Mg25(3He,d)26Al to high spin states

Proton stripping with the 55.2 MeV /sup 25/Mg(/sup 3/He,d)/sup 26/Al reaction has been used to populate 6/sup -/ states known from other reactions or by analogy to the states excited in /sup 26/Mg by electron scattering. Spectroscopic factors are, in general, in good agreement with those obtained in a lower resolution study of the /sup 25/Mg(..cap alpha..,t)/sup 26/Al reaction, when similar reaction distorted-wave Born approximation calculations are made. More high-lying states are found in the (/sup 3/He,d) study than in the (..cap alpha..,t) work. The differences between scattering and single-proton stripping excitation of the simple stretched states are confirmed.

Mg 25 ( 3 He,d ) 26 Al to high spin states

Proton stripping with the 55.2 MeV /sup 25/Mg(/sup 3/He,d)/sup 26/Al reaction has been used to populate 6/sup -/ states known from other reactions or by analogy to the states excited in /sup 26/Mg by electron scattering. Spectroscopic factors are, in general, in good agreement with those obtained in a lower resolution study of the /sup 25/Mg(..cap alpha..,t)/sup 26/Al reaction, when similar reaction distorted-wave Born approximation calculations are made. More high-lying states are found in the (/sup 3/He,d) study than in the (..cap alpha..,t) work. The differences between scattering and single-proton stripping excitation of the simple stretched states are confirmed.