Selective Excitation of One-, Two-, and Three-Nucleon Configurations in Transfer Reactions Induced by Heavy Ions

Spectroscopy of Exotic Nuclei Using Heavy-Ion Transfer Reactions

“…3(a) exhibits excited states at 0.23, 2.10, and 4.79 MeV (±150 keV), although the latter two are somewhat ambiguous because of the close proximity of U C excited states at 1.995 and 4.794 MeV. The selectivity of the reaction appears to be similar to that 16 of ( 7 Li, 7 Be) and quite different from that of the (t, 3 He) reaction, 17 which established excited states at 88, 241, and 420 keV. Although the detailed mechanism of these rearrangement reactions is poorly understood at present, it appears that the heavy-ion case preferentially excites high-spin states.…”

“…The reliability of detection was further improved by comparing events in the independent TOF-versus-(AE) 1 identification; this comparison almost completely eliminated spurious identifications in either AE measurement. 3 All the parameters were stored on magnetic tape event by event for off-line analysis.…”

“…The accuracy of the method, including the calibration of the magnetic field of the spectrometer, was checked by using other reactions of known Q value, e.g., ( n B, 13 The low cross section for 3n transfer follows the trend of high-energy heavy-ion reactions of favoring the transfer of bound clusters. 3 However the selectivity of the reaction shows that some correlation is still present. For example, in 31 Si only two states are populated in the first 4 MeV of excitation: the ground state, which has the dominant structure (s 1/2 ) 2 d 3/2 in both the simple and the extended shell-model calculations, 10 and a state at 3.15 MeV of dominant structure (s 1/2 ) 2 / 7/2 .…”

“…The two most popular theories explain this second band as one with less pairing than in the ground state. The Coriolis antipairing models of Kumar, 1 Krumlinde, 2 and Faessler et al 3 propose a reduction in the pairing strength between many or all neutrons because of the Coriolis interaction, while the rotation-alignment model of Stephens and Simon 4 requires pairing collapse between only one pair of…”

Spin and parity determinations of excited 15N based on polarized and unpolarized 12C(7Li,α)15N reaction data at Elab=34MeV

“…Early three-particle transfer reaction studies with 12 C and 16 O as targets showed tremendous selectivity in the states populated in the final nuclei 15 N and 19 F, respectively [1][2][3]. The lack of definite spin and parity assignments for levels at high excitation energies have impeded the further development of a simple triton cluster model [4,5] used to describe some of the strongly lower energy populated states in 15 N and 19 F. The present work is intended to provide new information on the three-particle cluster structure of 15 N. We determine cross sections, angular distributions and vector analyzing powers for the 12 C( 7 Li, a) 15 N reaction by using a 34 MeV polarized 7 Li beam.…”