Gamow-Teller strength in the continuum and quenching problem

✍ Scribed by H. Sakai; T. Wakasa; H. Okamura; T. Nonaka; T. Ohnishi; K. Yako; K. Sekiguchi; S. Fujita; Y. Satou; H. Otsu; T. Uesaka; S. Ishida; N. Sakamoto; M.B. Greenfield; K. Hatanaka

• Book ID: 104337238
• Publisher: Elsevier Science
• Year: 1999
• Tongue: English
• Weight: 525 KB
• Volume: 649
• Category: Article
• ISSN: 0375-9474
• DOI: 10.1016/s0375-9474(99)00069-x

✦ Synopsis

Differential cross sections at 01~b = 0.0 ° 12,3 ° and a complete set of polarization transfer observables at 01~b = 0.0 ° are measured for the 9°Zr(p, n) reaction at Tp = 295 MeV. A multipole decomposition (MD) technique is applied to the cross sections to extract partial cross sections cr L with L=0, 1, 2, and 3 contributions. A significant amount of CrL-~ is found in the highly excited continuum region, After subtracting the estimated iso-w~ctor spin-monopole strength froln aL=O, the Gamow-Teller (GT) strength B(GT) is deduced to be S q = Z B(GT) = 28 + 1.6 :t: 5.4. The total spin transfer E(0 °) which is independent of the nuclear reaction mechanisms such as the effectiw~ nucleon-imcleon inter~ctioll or distortions is derived from the complete set of polarization transfer observables. It is close to unily up to 50 MeV excitation indicating the strong spin-flip character of the continumn. By using the relation between the polarization transfer observables the fractions of natural-parity and unnatural-parity transitions are also obtained and the dominant(. of unnatural-parity transitions in the continuum is found. These results are consistenl with those derived from the MD analysis. The S:~ -S,~+ value is 27.1 and this is 9(}¢X: o[ Ikeda's sum rule value of 3(N -Z)=30. Consequently it is concluded that the quenching of the GT strength is small att¢t the quenching mechanism due to the __kN admixture' seems to play' a minor role.