Valence and inner hole responses via the {sup 208}Pb({rvec d},t){sup 207}Pb reaction at E{sub d}=200thinspMeV and form factor dependence

Journal Article · Thu Oct 01 00:00:00 EDT 1998 · Physical Review, C

DOI:https://doi.org/10.1103/PhysRevC.58.2192· OSTI ID:659343

Langevin-Joliot, H; Van de Wiele, J; Jourdan, F; Guillot, J; Rosier, L H; Willis, A; Djalali, C; Morlet, M ^[1]; Gerlic, E ^[2]; Djalali, C ^[3]; Tomasi-Gustafsson, E ^[4]; Blasi, N; Micheletti, S ^[5]; van der Werf, S Y ^[6]

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1. Institut de Physique Nucleaire, IN2P3-CNRS, BP No. 1-91406 Orsay (France)
2. Institut de Physique Nucleaire, IN2P3-CNRS, 43 Bd du 11 Novembre, 69622 Lyon-Villeurbanne (France)
3. Department of Physics and Astronomy, University of South Carolina, Columbia, South Carolina 29208 (United States)
4. DAPNIA-SPhN and Laboratoire National Saturne, CEN-Saclay, F 91191, Gif sur Yvette (France)
5. INFN and University of Milan, Physics Department, Via Celoria 16, 20133 Milan (Italy)
6. Kernfysisch Versneller Instituut, 9747 AA Groningen (The Netherlands)

The study of the {sup 208}Pb({rvec d},t){sup 207}Pb reaction at E{sub d}=200thinspMeV has been extended up to typically E{sub x}=40thinspMeV in {sup 207}Pb using a polarized beam with both vector and tensor components. Two-step pickup reactions involving low multipolarity collective transitions have been evaluated for the first time via systematic coupled channel calculations, allowing a new approach of the background determination. The ({rvec d},t) observables corresponding to the overlapping 1h{sub 11/2}, 1g{sub 7/2}, and 1g{sub 9/2} inner hole responses have been analyzed up to E{sub x}=25thinspMeV via a least squares fit procedure. Necessary input values were deduced for hole states of interest from finite range distorted wave (DWBA) calculations. The optical parameters and the range function were those successfully used in a previous survey of valence state observables. The highest j transitions are enhanced in the reaction and analyzing powers exhibit strongly characteristic features for j{sub {minus}}=l{minus}1/2 versus j{sub +}=l+1/2 states. We have calculated for the first time the separation energy dependence of nlj transition observables, taking into account the form factor modifications induced by the hole coupling with surface vibrations. The calculations have been performed in the framework of the quasiparticle-phonon model (QPM). This analysis (QPMFF) predicts a large variation of differential cross sections with excitation energy of the hole fragments, while angular distribution shapes remain quite stable. The strength distributions resulting of the QPMFF analysis and of a standard analysis using DWBA observables calculated at the centroid energies are systematically compared. As a general rule, the QPMFF analysis increases the strength concentration toward lower excitation energy. The corresponding 1h{sub 11/2}, 1g{sub 7/2}, and the tentative 1g{sub 9/2} strength distributions are compared and discussed with the available theoretical calculations. In particular, the narrower spreading widths deduced via the QPMFF analysis are quite well predicted by the calculation of spectral functions in a modified mean field. The 1i{sub 13/2} and 1h{sub 9/2} valence strength distributions are revisited along this new approach and found to be in fair agreement with the fragmentation predicted by the QPM, which is not the case of inner hole strength distributions. {copyright} {ital 1998} {ital The American Physical Society}

• OSTI ID: 659343
• Journal Information: Physical Review, C, Vol. 58, Issue 4; Other Information: PBD: Oct 1998
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
DWBA
LEAD 208 TARGET
LEAD 207
DEUTERON REACTIONS
NUCLEAR REACTIONS
FORM FACTORS
QUASIPARTICLE-PHONON MODEL
TRANSFER REACTIONS
COUPLED CHANNEL THEORY