Gamow-Teller strength in the continuum and quenching problem

H. Sakai, Tomotsugu 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

Research output: Contribution to journalArticle

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Abstract

Differential cross sections at θ lab = 0.0° 12.3° and a complete set of polarization transfer observables at θ lab = 0.0° are measured for the 90 Zr(p, n) reaction at T p = 295 MeV. A multipole decomposition (MD) technique is applied to the cross sections to extract partial cross sections σ L with L=0, 1, 2, and 3 contributions. A significant amount of σ L =0 is found in the highly excited continuum region. After subtracting the estimated iso-vector spin-monopole strength from σ L =0, the Gamow-Teller (GT) strength B(GT) is deduced to be S β- = ∑ B(GT) = 28 ± 1.6 ± 5.4. The total spin transfer ∑(0°) which is independent of the nuclear reaction mechanisms such as the effective nncleon-nucleon interaction or distortions is derived from the complete set of polarization transfer observables. It is close to unity up to 50 MeV excitation indicating the strong spin-flip character of the continuum. By using the relation between the polarization transfer observables the fractions of natural-parity and unnatural-parity transitions are also obtained and the dominance of unnatural-parity transitions in the continuum is found. These results are consistent with those derived from the MD analysis. The S β- - S β+ value is 27.1 and this is 90% of Ikeda's sum rule value of 3(N - Z)=30. Consequently it is concluded that the quenching of the GT strength is small and the quenching mechanism due to the ΔN admixture seems to play a minor role.

Original languageEnglish
Pages (from-to)251-259
Number of pages9
JournalNuclear Physics A
Volume649
Issue number1-4
DOIs
Publication statusPublished - Mar 29 1999
Externally publishedYes

Fingerprint

quenching
continuums
parity
multipoles
cross sections
polarization
decomposition
admixtures
nuclear reactions
monopoles
sum rules
unity
excitation
interactions

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics

Cite this

Sakai, H., Wakasa, T., Okamura, H., Nonaka, T., Ohnishi, T., Yako, K., ... Hatanaka, K. (1999). Gamow-Teller strength in the continuum and quenching problem. Nuclear Physics A, 649(1-4), 251-259. https://doi.org/10.1016/S0375-9474(99)00069-X

Gamow-Teller strength in the continuum and quenching problem. / Sakai, H.; Wakasa, Tomotsugu; Okamura, H.; Nonaka, T.; Ohnishi, T.; Yako, K.; Sekiguchi, K.; Fujita, S.; Satou, Y.; Otsu, H.; Uesaka, T.; Ishida, S.; Sakamoto, N.; Greenfield, M. B.; Hatanaka, K.

In: Nuclear Physics A, Vol. 649, No. 1-4, 29.03.1999, p. 251-259.

Research output: Contribution to journalArticle

Sakai, H, Wakasa, T, Okamura, H, Nonaka, T, Ohnishi, T, Yako, K, Sekiguchi, K, Fujita, S, Satou, Y, Otsu, H, Uesaka, T, Ishida, S, Sakamoto, N, Greenfield, MB & Hatanaka, K 1999, 'Gamow-Teller strength in the continuum and quenching problem', Nuclear Physics A, vol. 649, no. 1-4, pp. 251-259. https://doi.org/10.1016/S0375-9474(99)00069-X
Sakai H, Wakasa T, Okamura H, Nonaka T, Ohnishi T, Yako K et al. Gamow-Teller strength in the continuum and quenching problem. Nuclear Physics A. 1999 Mar 29;649(1-4):251-259. https://doi.org/10.1016/S0375-9474(99)00069-X
Sakai, H. ; Wakasa, Tomotsugu ; Okamura, H. ; Nonaka, T. ; Ohnishi, T. ; Yako, K. ; Sekiguchi, K. ; Fujita, S. ; Satou, Y. ; Otsu, H. ; Uesaka, T. ; Ishida, S. ; Sakamoto, N. ; Greenfield, M. B. ; Hatanaka, K. / Gamow-Teller strength in the continuum and quenching problem. In: Nuclear Physics A. 1999 ; Vol. 649, No. 1-4. pp. 251-259.
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T1 - Gamow-Teller strength in the continuum and quenching problem

AU - Sakai, H.

AU - Wakasa, Tomotsugu

AU - Okamura, H.

AU - Nonaka, T.

AU - Ohnishi, T.

AU - Yako, K.

AU - Sekiguchi, K.

AU - Fujita, S.

AU - Satou, Y.

AU - Otsu, H.

AU - Uesaka, T.

AU - Ishida, S.

AU - Sakamoto, N.

AU - Greenfield, M. B.

AU - Hatanaka, K.

PY - 1999/3/29

Y1 - 1999/3/29

N2 - Differential cross sections at θ lab = 0.0° 12.3° and a complete set of polarization transfer observables at θ lab = 0.0° are measured for the 90 Zr(p, n) reaction at T p = 295 MeV. A multipole decomposition (MD) technique is applied to the cross sections to extract partial cross sections σ L with L=0, 1, 2, and 3 contributions. A significant amount of σ L =0 is found in the highly excited continuum region. After subtracting the estimated iso-vector spin-monopole strength from σ L =0, the Gamow-Teller (GT) strength B(GT) is deduced to be S β- = ∑ B(GT) = 28 ± 1.6 ± 5.4. The total spin transfer ∑(0°) which is independent of the nuclear reaction mechanisms such as the effective nncleon-nucleon interaction or distortions is derived from the complete set of polarization transfer observables. It is close to unity up to 50 MeV excitation indicating the strong spin-flip character of the continuum. By using the relation between the polarization transfer observables the fractions of natural-parity and unnatural-parity transitions are also obtained and the dominance of unnatural-parity transitions in the continuum is found. These results are consistent with those derived from the MD analysis. The S β- - S β+ value is 27.1 and this is 90% of Ikeda's sum rule value of 3(N - Z)=30. Consequently it is concluded that the quenching of the GT strength is small and the quenching mechanism due to the ΔN admixture seems to play a minor role.

AB - Differential cross sections at θ lab = 0.0° 12.3° and a complete set of polarization transfer observables at θ lab = 0.0° are measured for the 90 Zr(p, n) reaction at T p = 295 MeV. A multipole decomposition (MD) technique is applied to the cross sections to extract partial cross sections σ L with L=0, 1, 2, and 3 contributions. A significant amount of σ L =0 is found in the highly excited continuum region. After subtracting the estimated iso-vector spin-monopole strength from σ L =0, the Gamow-Teller (GT) strength B(GT) is deduced to be S β- = ∑ B(GT) = 28 ± 1.6 ± 5.4. The total spin transfer ∑(0°) which is independent of the nuclear reaction mechanisms such as the effective nncleon-nucleon interaction or distortions is derived from the complete set of polarization transfer observables. It is close to unity up to 50 MeV excitation indicating the strong spin-flip character of the continuum. By using the relation between the polarization transfer observables the fractions of natural-parity and unnatural-parity transitions are also obtained and the dominance of unnatural-parity transitions in the continuum is found. These results are consistent with those derived from the MD analysis. The S β- - S β+ value is 27.1 and this is 90% of Ikeda's sum rule value of 3(N - Z)=30. Consequently it is concluded that the quenching of the GT strength is small and the quenching mechanism due to the ΔN admixture seems to play a minor role.

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JF - Nuclear Physics A

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