Gamow-Teller transitions toP32studied through theS32(d,He2)reaction atEd=170MeV

Abstract

The S-32(d,He-2)P-32 charge-exchange reaction has been studied at forward angles and at an incident energy of E-d=170 MeV. The two protons in the S-1(0)(pp) state (indicated as He-2) were both momentum analyzed and detected by the same spectrometer and detector. High resolution He-2 spectra have been obtained allowing identification of many levels in the residual nucleus with high precision. The (d,He-2) reaction selectively excites spin-isospin-flip transitions, and at vanishing momentum transfer these are largely governed by the Gamow-Teller transition operator for the beta(+) direction. In the case of the self-conjugate nucleus S-32, the (d,He-2) probe is calibrated against the elementary (p,n) probe going into the mirror beta(-) direction. The deduced results are compared with those obtained from (p,p(')) and (e,e(')) reactions, which excite the same levels in the isospin multiplet. Angular distributions of cross sections for the (d,He-2) reaction are presented and compared with DWBA calculations. A level-by-level comparison with shell-model calculations using the USD interaction has been performed, and the structure of the l-forbidden ground state transition is discussed. From the comparison with (p,p(')), (e,e(')), and (p,n) data the isospin-analog J(pi)=1(+) levels in the triplet of the A=32 nuclei are deduced.