Isospin symmetry of T{sub z}={+-}3/2{yields}{+-}1/2 Gamow-Teller transitions in A=41 nuclei

Journal Article · Mon Nov 01 04:00:00 EST 2004 · Physical Review. C, Nuclear Physics

DOI:https://doi.org/10.1103/PhysRevC.70.054311· OSTI ID:20695729

Fujita, Y; Shimbara, Y; Adachi, T; Fujita, H ^[1]; Berg, G P.A. ^[2]; Brown, B A ^[3]; Hatanaka, K; Kamiya, J; Nakanishi, K; Sakemi, Y; Shimizu, Y; Tameshige, Y; Wakasa, T ^[2]; Sasaki, S ^[4]; Uchida, M; Yosoi, M ^[5]

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1. Department of Physics, Osaka University, Toyonaka, Osaka 560-0043 (Japan)
2. Research Center for Nuclear Physics, Osaka University, Ibaraki, Osaka 567-0047 (Japan)
3. NSCL and Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824 (United States)
4. Shizuoka Institute of Technology, Fukuroi, Shizuoka 437-8555 (Japan)
5. Department of Physics, Kyoto University, Kyoto 606-8502 (Japan)

Under the assumption that isospin T is a good quantum number, isobaric analog states and various analogous transitions are expected in isobars with mass number A. The strengths of T{sub z}={+-}3/2{yields}{+-}1/2 analogous Gamow-Teller (GT) transitions and analogous M1 transitions within the A=41 isobar quartet are compared in detail. The T{sub z}=+3/2{yields}+1/2 GT transitions from the J{sup {pi}}=3/2{sup +} ground state of {sup 41}K leading to excited J{sup {pi}}=1/2{sup +}, 3/2{sup +}, and 5/2{sup +} states in {sup 41}Ca were measured using the ({sup 3}He,t) charge-exchange reaction. With a high energy resolution of 35 keV, many fragmented states were observed, and the GT strength distribution was determined up to 10 MeV excitation energy (E{sub x}). The main part of the strength was concentrated in the E{sub x}=4-6 MeV region. A shell-model calculation could reproduce the concentration, but not so well details of the strength distribution. The obtained distribution was further compared with two results of {sup 41}Ti {beta} decay studying the analogous T{sub z}=-3/2{yields}-1/2 GT strengths. They reported contradicting distributions. One-to-one correspondences of analogous transitions and analog states were assigned up to E{sub x}=6 MeV in the comparison with one of these {sup 41}Ti {beta}-decay results. Combining the spectroscopic information of the analog states in {sup 41}Ca and {sup 41}Sc, the most probable J{sup {pi}} values were deduced for each pair of analog states. It was found that 5/2{sup +} states carry the main part of the observed GT strength, while much less GT strength was carried by 1/2{sup +} and 3/2{sup +} states. The gross features of the GT strength distributions for each J were similar for the isospin analogous T{sub z}={+-}3/2{yields}{+-}1/2 transitions, but the details were somewhat different. From the difference of the distributions, isospin-asymmetry matrix elements of {approx_equal}8 keV were deduced. The Coulomb displacement energy, which is sensitive to the configuration of states, showed a sudden increase of about 50 keV at the excitation energy of 3.8 MeV. The strengths of several M1 transitions to the IAS in {sup 41}Ca were compared with the strengths of analogous GT transitions. It was found that ratios of the M1 and GT transition strengths were similar, suggesting that the contributions of the l{tau} term in M1 transitions are small.

• OSTI ID: 20695729
• Journal Information: Physical Review. C, Nuclear Physics, Journal Name: Physical Review. C, Nuclear Physics Journal Issue: 5 Vol. 70; ISSN 0556-2813; ISSN PRVCAN
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ASYMMETRY
BETA DECAY
CALCIUM 41
CHARGE-EXCHANGE REACTIONS
COMPARATIVE EVALUATIONS
DISTRIBUTION
ENERGY RESOLUTION
EXCITATION
GAMOW-TELLER RULES
GROUND STATES
HELIUM 3
HELIUM 3 REACTIONS
ISOBARIC ANALOGS
ISOSPIN
KEV RANGE
M1-TRANSITIONS
MATRIX ELEMENTS
MEV RANGE
OSCILLATOR STRENGTHS
PARITY
POTASSIUM 41
SCANDIUM 41
SHELL MODELS
SPIN
SYMMETRY
TITANIUM 41