Fragmentation and splitting of Gamow-Teller resonances in Sn([sup 3]He,[ital t])Sb charge-exchange reactions, [ital A]=112--124
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1120 (United States)
- Kernfysisch Versneller Instituut, Zernikelaan 25, 9747 AA Groningen (Netherlands)
- Indiana University Cyclotron Facility, Bloomington, Indiana 47405 (United States)
- University of Notre Dame, Notre Dame, Indiana 46556 (United States)
- Research Center for Nuclear Physics, Osaka University, Osaka 567 (Japan)
Fragmentation and splitting of the Gamow-Teller (GT) strength has been observed in a systematic study of the ([sup 3]He,[ital t]) charge-exchange reaction at [ital E]([sup 3]He)=200 MeV over the entire range of stable Sn isotopes. Triton energy spectra were observed with a high-resolution magnetic spectrometer at angles near [theta]=0[degree] where [Delta][ital L]=0 transitions are enhanced. Excitation energies, widths, 0[degree] cross sections, and strengths [ital B](GT) were determined. A theoretically predicted configuration splitting of the main GT component into two components, expected to be dominant near [ital A]=118 at the onset of the filling of the 1[ital h][sub 11/2] neutron orbital, could not be observed. This may be due to the fact that the total widths of the resonances of 5--6 MeV exceed the predicted splitting. A comparison of the 0[degree] cross sections for the transitions to the GT resonances and the isobaric analog states leads to strengths [ital B](GT) for the main Gamow-Teller components of typically 65% of the sum-rule value of 3([ital N][minus][ital Z]). Three to four additional Gamow-Teller fragments were observed in all final nuclei at lower excitation energies. The excellent energy resolution of the experiment made it possible to observe a pronounced fine structure in these low-lying resonances which is believed to be due to coupling to two-particle--two-hole doorway states. Also seen with all target nuclei was a systematic sequence of strong [ital J][sup [pi]]=1[sup +] states near the ground states in all Sb isotopes ([ital E][sub [ital x]]=0 to 220 keV). In addition, strong [Delta][ital L]=1 resonances were observed in all nuclei at excitation energies of typically 20 MeV. Furthermore, nonresonant background from quasifree charge exchange was observed. An average of [similar to]85% of all excess neutrons seems to contribute to this background in approximate agreement with results from ([ital e],[ital e][prime][ital p]) experiments.
- OSTI ID:
- 6852125
- Journal Information:
- Physical Review, C (Nuclear Physics); (United States), Vol. 51:2; ISSN 0556-2813
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
HELIUM 3 REACTIONS
CHARGE-EXCHANGE REACTIONS
GAMOW-TELLER RULES
TIN ISOTOPES
ANTIMONY ISOTOPES
CROSS SECTIONS
ENERGY SPECTRA
EXCITATION
GROUND STATES
MAGNETIC SPECTROMETERS
NUCLEAR FRAGMENTATION
SUM RULES
TRITONS
WIDTH
CHARGED PARTICLES
CHARGED-PARTICLE REACTIONS
DIMENSIONS
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EQUATIONS
ISOTOPES
MEASURING INSTRUMENTS
NUCLEAR REACTIONS
SPECTRA
SPECTROMETERS
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