Systematics of isospin character of transitions to the21+and31

Abstract

DiII'erential cross sections for exciting the 2&+ and 3& states of ' ' ' Zr with 70-MeV Li ions have been measured. Calculations of the cross sections have been performed using a deformed optical model potential (DOMP) with OMP deduced from fits to the elastic data, as well as a folding model with an e6'ective nucleon-nucleon interaction with a Yukawa form factor obtained from fits to the elastic data and transition densities obtained from open-shell random phase approximation (RPA) calculations. The DOMP fits to the data yield values of M"/M~which are in good agreement with those predicted using the RPA. For the 2&+ states, we find M"/M~increases from less than N/Z to greater than N/Z in going from Zr to Zr. However, for the 3, states M"/M~remains less than N/Z for all cases, a result which is in disagreement with previous works. The folding model, with the RPA transition densities, provides good agreement with the 2&+ measurements, but underpredicts the cross sections for the 3& states. A reanalysis of the earlier data from excitation of these states by (a, a') reactions removes much of the apparent discrepancies between those measurements and other measurements, including the ones reported here. The localization of the Li interaction is also discussed.PACS number(s): 21.10.Hw, 27.60. +j

Lifetime of the31−state and octupole collectivity inZrHören1, Auble2, Satchler3 et al. 1993Phys. Rev. CSelf Cite171190View full textAdd to dashboardCite

“…[ (rather than the value 0.12 e b used therein) would lead to a ratio of neutron to proton multipole transition matrix elements of M"/M &0.9 if the Li scattering data were analyzed using the DOMP. We have reanalyzed those data using the DOMP and our new value of 8(E3)t and find M"/M~= 0.51 which is considerably smaller than the value 1.22 obtained from QRPA calculations [5]. A small adjustment in the octupole-octupole strength used in the QRPA calculation can result in B(E3))=0.18 e b with M"/M~r emaining about the same, i.e.…”

“…We have performed two folding model calculations of the inelastic cross section for exciting the 3& state with 70-MeV Li ions using the effective nucleon-nucleon interaction given in Ref. [5]. In one calculation, we scaled the RPA transition densities [5] in accordance with our deduced 8 (E3)f. As expected, the calculated cross sections were in much better agreement with the data than was found to be the case in Ref.…”

“…It was found that to fit inelastic Li data for the 3& state using the deformed optical model potential (DOMP) with this reported B(E3)1' [1,2] would require *Present address: Lawrence Berkeley Laboratory, Berkeley, CA 94720. [5] M"/M (0.5, where M"and M are the neutron and proton multipole transition matrix elements, respectively.…”

“…On the other hand, it might imply that the interpretation of the parameters (deformation lengths) deduced from a DOMP analysis of the inelastic data is incorrect [5]. It has been noted in Ref.…”

“…It has been noted in Ref. [5] that there was an inconsistency between DOMP and folding model calculations of the inelastic cross sections for 3 The target and stopper foils were carefully aligned by optical means with an accuracy of &0. 2'.…”