(p,d) Reaction onN=ZNuclei in the2s−1dShell

Abstract

An investigation of the (p,d) reaction on N=Z nuclei in the 2s-ld shell has been made to obtain spectroscopic information and to study the l n = 2 /-dependence for the (p,d) reaction. The experiments were performed with 24 Mg, 28 Si, 32 S, 36 Ar, and 40 Ca as target nuclei, and virtually all of the 2s-ld shell hole strength was observed. Deuteron angular distributions for strongly excited levels in 23 Mg, 27 Si, 31 S, 36 Ar, and 39 Ca were measured for laboratory angles from 10° to 155°, and spectroscopic factors were obtained using distorted-wave Born-approximation (DWBA) calculations. The / dependence for the pickup of an l" = 2 neutron appears mostly in the forward angles of the angular distributions and seems to follow systematic trends through the 2s-ld shell, thus suggesting spin assignments for levels in 31 S, 38 Ar, and 39 Ca. Appreciable configuration mixing is found to exist in the ground-state wave functions of all the nuclei investigated. Of particular interest are the l n = 1 levels excited in the ^Mg^^J^Mg and 28 Si (p,d) 27 Si reactions, which could arise from the removal of either Ip-or 2j?>-shell neutrons. The ground states of 36 Ar and 40 Ca are observed to contain appreciable mixing with the fy% shell, and evidence exists for a small [2p2 2 admixture in the 40 Ca ground state. The level orders of the residual nuclei and the DWBA spectroscopic factors are discussed in terms of the strong-coupling rotational model and Nilsson-model wave functions. Evidence for strong rotational band mixing is apparent in many cases. (p,d)REACTION ON N = Z NUCLEI

One-neutron knockout reactions on proton-rich nuclei withN=16

“…In focus mode the beam is dispersed in the focal plane. The shape of the 34 Ar momentum distribution is nicely reproduced by a superposition of error functions. The theoretical momentum distributions were then folded with this curve to take into account the broadening induced by the S800 optics setting.…”

“…An exotic multicomponent beam consisting of the N =16 isotones 32 S, 33 Cl, and 34 Ar was obtained by fragmentation of a 150 MeV/ nucleon 36 Ar primary beam provided by the Coupled Cyclotron Facility at the National Superconducting Cyclotron Laboratory (NSCL). The fragmentation target (1034 mg/ cm 2 9 Be) was located at the midacceptance target position of the large-acceptance A1900 fragment separator [16].…”

“…As a result, the momentum distribution in the S800 focal plane is broader than in the normally used "dispersion matched" mode. The momentum profile of the 34 Ar projectiles is shown in Fig. 3(b).…”

“…IV. Ar knockout residues (a) and the 34 Ar "unreacted" beam (b). In focus mode the beam is dispersed in the focal plane.…”

“…In this paper we report the study of proton-rich nuclei with Z = 16, 17, and 18 using the one-neutron knockout reactions 9 Be͑ 32 S, 31 S+␥͒X, 9 Be͑ 33 Cl, 32 Cl+ ␥͒X, and 9 Be͑ 34 Ar, 33 Ar+ ␥͒X in inverse kinematics. These cases have higher neutron-separation energies, 15.04, 15.74, and 17.07 MeV, respectively, than those studied before.…”