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7 results on '"Greenfield MB"'

1. Direct proton decay from the Gamow-Teller resonance in 208Bi

Author

Akimune, H, Daito, I, Fujita, Y, Fujiwara, M, Greenfield, MB, Harakeh, M N, Inomata, T, Janecke, J, Katori, K, Nakayama, S, Sakai, H, Sakemi, Y, Tanaka, M, and Yosoi, M

Subjects
STATES, ISOBARIC ANALOG, HE-3,T REACTION, Nuclear Theory, STRENGTH, SCATTERING, TRANSITIONS, CHARGE-EXCHANGE, Nuclear Experiment, INTERMEDIATE ENERGIES
Abstract

Spin-isospin excitations in Bi-208 have been investigated using the Pb-208(He-3,t)Bi-208 reaction at and near theta approximate to 0 degrees at E(He-3)=450 MeV. The microscopic structure of the Gamow-Teller resonance (GTR), the isobaric analog state (IAS), and the spin-flip dipole (Delta L = 1) resonance (SDR) in Bi-208 has been studied by observing their direct proton decays to the low-lying neutron-hole states in Pb-207. Decay protons were measured at backward angles in coincidence with tritons detected at and near 0 degrees. The total branching ratio for proton decay from the GTR is determined to be only 4.9+/-1.3%. The total branching ratio for proton decay from the SDR amounts to 14.1+/-4.2%. The deduced total widths as well as the total and partial proton escape widths of the GTR and IAS are found to be in reasonable agreement with recent theoretical estimates obtained in the framework of the continuum Tamm-Dancoff approximation.

Published
1995

2. Gamow-Teller strength distributions in 48Sc by the 48Ca(p,n) and 48Ti(n,p) reactions and two-neutrino double-beta decay nuclear matrix elements.

Author

Yako K, Sasano M, Miki K, Sakai H, Dozono M, Frekers D, Greenfield MB, Hatanaka K, Ihara E, Kato M, Kawabata T, Kuboki H, Maeda Y, Matsubara H, Muto K, Noji S, Okamura H, Okabe TH, Sakaguchi S, Sakemi Y, Sasamoto Y, Sekiguchi K, Shimizu Y, Suda K, Tameshige Y, Tamii A, Uesaka T, Wakasa T, and Zheng H

Abstract

The double-differential cross sections for the 48Ca(p,n) and 48Ti(n,p) reactions were measured at 300 MeV. A multipole decomposition technique was applied to the spectra to extract the Gamow-Teller (GT) components. The integrated GT strengths up to an excitation energy of 30 MeV in 48Sc are 15.3+/-2.2 and 2.8+/-0.3 in the (p,n) and (n,p) spectra, respectively. In the (n,p) spectra additional GT strengths were found above 8 MeV where shell models within the fp shell-model space predict almost no GT strengths, suggesting that the present shell-model description of the nuclear matrix element of the two-neutrino double-beta decay is incomplete.

Published
2009
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3. Dipole excitation of alpha clusters in (6)Li and (7)Li.

Author

Nakayama S, Yamagata T, Akimune H, Daito I, Fujimura H, Fujita Y, Fujiwara M, Fushimi K, Greenfield MB, Kohri H, Koori N, Takahisa K, Tamii A, Tanaka M, and Toyokawa H

Abstract

Dipole excitations in highly excited energy regions of (6)He and (7)He nuclei were investigated via the ((7)Li,(7)Be) reaction with an incident energy of 65A MeV at forward scattering angles. The resonances at Q approximately equal to -30 MeV observed commonly for both (6)Li and (7)Li targets were found to be excited via both spin-flip and spin-nonflip transitions with DeltaL = 1. Based on the observed excitation energy, width, and cross section of each resonance, the relevant resonances are inferred to be analogs of the dipole resonances of alpha clusters in the (6)Li and (7)Li nuclei.

Published
2001
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