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Taddeucci, T. N.; Rapaport, J.; Bainum, D.E.; Goodman, C.D.; Foster, C.C.; Gaarde, C.; Larsen, J.S.; Goulding, C.A.; Hören, D.J.; Masterson, T.; Sugarbaker, E.

doi:10.1103/physrevc.25.1094

Cited by 60 publications

(55 citation statements)

References 23 publications

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“…An alternative calibration, which does not require knowledge of absolute cross sections, can be done internally within the spectrum with an empirical GTto-F strength ratio. 15 B{GT) values derived from both calibrations are in agreement, with estimated uncertainties of ± 15%, except at low E x where statistical uncertainties dominate.…”

supporting

confidence: 73%

Gamow-Teller Strength Function inGe71via the (p, n) Reaction at M

et al. 1985

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The Gamow-Teller strength function in 71 Ge has been measured by use of the reaction 71 Ga(/?,/2 ) at E p = 120 and 200 MeV. While a significant fraction of the total strength is associated with excited states located below particle-emission threshold, the first excited state exhibits little strength. Excited-state contributions to the total solar-neutrino capture rate for a 71 Ga detector are about 14 solar neutrino units for the neutrino spectrum of the standard solar model and about 3-4 solar neutrino units for representative nonstandard solar models.PACS numbers: 25.40. Ep, 23.40.Hc, 27.50. + e, 96.60.Kx The discrepancy between the solar-neutrino capture rate observed in the 37 C1 experiment 1 and that predicted by the standard solar model 2 (SSM) has been a problem for almost two decades. The 37 C1 detector is sensitive only to neutrino energies above 814 keV, resulting in a response which is primarily dependent on the higher-energy (0-14 MeV) 8 B neutrinos. 3 Solar-neutrino capture via the reaction 71 Ga(v e , e~) ll Ge has a threshold 4 of only 233 keV and has been proposed 5 as a way to determine whether the 37 C1 discrepancy is caused by an inadequacy in our understanding of the solar interior (astrophysics) or by neutrino oscillations or decay (neutrino propagation). The flux of low-energy (0-420 keV) neutrinos arising from the reaction p +p -> 2 H + e + + v is relatively insensitive to the solar model, but neutrino oscillations would for some range of neutrino masses reduce solar electron-neutrino fluxes by factors which depend upon neutrino energy. 4,6 The neutrino-capture cross section to the ground state (g.s.) of 71 Ge can be calculated reliably by use of the ft value for 71 Ge(/3 + ) 71 Ga. On the basis of betadecay systematics in the neighboring mass region, Bahcall 7 estimated small contributions to the total capture cross section from low-lying excited states in 71 Ge. It follows that 63% of the capture events on 71 Ga would come from p+p neutrinos if the SSM flux is assumed. Transitions to highly excited states would enhance the overall response of the Ga detector but thereby dilute its relative sensitivity to p +p neutrinos. Since electron capture (EC) half-lives cannot be measured for the excited states and theoretical calculations 8,9 are model dependent, we have utilized the established relationship 10 between /3-decay Gamow-Teller transition strength B(GT) and (p,n) zero-degree differential cross section cr(0°) for E P ~~ 100-200 MeV to mea-

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supporting

confidence: 73%

Gamow-Teller Strength Function inGe71via the (p, n) Reaction at M

et al. 1985

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“…(20). The ratios based on the SP84 amplitudes agree well with values extracted (21) from the (p, n) reaction below -200 MeV. Figure 2 shows the density dependence of the central parts of the G-matrix interaction based on the Bonn potential (GBJ) at q = 0, for Tp = 175 and 425 MeV.…”

Section: Effective Interactionssupporting

confidence: 72%

“…This is frequently done using an approximate distorted-wave expression (18) for the chargeexchange cross section at 0°, where B(F) and B(GT) are the squared Fermi and Gamow-Teller matrix elements (21); V,(O) is the interaction strength at zero momentum transfer; k,(,$) is the momentum of the incident (scattered) particle; is a distortion factor (18) a large extent which type of mode ( S = I or S = 0) should dominate the spectrum at a given incident energy and is also a quantity that may be compared with the free NN interaction; this is done in Fig. I .…”

Section: Isovector Excitations At Small Momentum Transfersmentioning

confidence: 99%

Nucleon charge-exchange reactions at intermediate energies

Love¹,

Klein²,

Franey³

et al. 1987

Can. J. Phys.

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The nucleon charge-exchange reaction is investigated as a probe of isovector modes of nuclear excitation at both small and large momentum transfer. The calculated and extracted properties of the isovector nucleon-nucleon interaction are discussed and illustrated with an emphasis on incident energies in excess of 100 MeV. Particular emphasis is placed on spin observables and the roles played by different parts of the nucleon-nucleon coupling in their determination. Recent measurements of transverse polarization transfer at 0' in the charge-exchange continuum are compared with distorted wave impulse approximation calculations using random-phase approximation transition densities.La reaction d'tchange de charge des nuclCons est Ctudite, dans le but d'explorer les modes isovectoriels d'excitation nuclkaire, pour les grands aussi bien que pour les faibles transferts d'irnpulsion. Les propriktks calculCes et extraites de 'l'interaction isovectorielle entre nuclCons sont discutkes et illustrCes en rnettant l'acccnt sur les energies suptrieures a 100 MeV. On insiste particuli2rement sur les observables de spin et sur les rbles joues dans leur determination par differentes parties du couplage nuclCon-nuclCon. Des rnesures rCcentes de transfert de polarisation transversale a 0" dans le continuum d'Cchange de charge sont cornparees avec des calculs faits dans I'approximation d'irnpulsion avec distorsion de l'onde, en utilisanf les densites de transition de I'approxirnation de phase alkatoire.Can. J. Phys. 65, 536 (1987) IntroductionThe study of charge-exchange nucleon-nucleus scattering at incident energies above 100 MeV has been extremely important for understanding isovector modes of excitation of the nucleus. Detailed theoretical investigations (1 -5) of (p, n) and (p, p') data indicate that the reaction mechanisms operative at these bombarding energies and for energy losses up to several tens of MeV are predominantly single step in nature. Moreover, it has been established (6, 7) that the nucleon (N) charge-exchange reaction. at intermediate energies preferentially excites nuclear spin-isospin modes. In a singlescattering picture, this means that the charge-exchange process is mediated primarily by the spin-isospin dependent part of the effective nucleon-nucleon (NN) interaction. Both t-matrix (7) and G-matrix (8,9) types of interactions provide good descriptions of experimental cross sections for those isovector spinflip excitations whose relevant aspects of nuclear structure are known (10-12). Thus, we may regard the strength and momentum-transfer profile of the spin-isospin dependent NN force to be used in medium-energy charge-exchange scattering as being known and focus primary attention on the nuclear response being probed.In Sect. 2, we consider the dynamic and symmetry properties of recently developed t-matrix and G-matrix interactions, and we illustrate the roles these properties play in probing the nuclear response. We consider isovector excitations at small momentum transfer in Sect. 3 and compare measure...

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“…Here k; and k& are the initial and final projectile momenta, respectively, J, =-V,(q =0) is the volume integral of the central (C) part of the effective projectile-target nucleon interaction, and N, is a distortion factor which summarizes the distortion and absorption effects in the scattering process in a single constant. Extensive tests [15) have verified the proportionality relation given in Eq. (1).…”

Section: Theoretical Developmentmentioning

confidence: 71%

Heavy-ion charge-exchange reactions and the measurement of Gamow-Teller strength

et al. 1992

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The applicability of intermediate-energy heavy-ion charge-exchange reactions for measuring GamowTeller strength in nuclei is studied. A strong absorption model for such reactions is developed. Within the framework of this model, we define a sensitivity function which determines the important region of the target transition density in momentum space. It is found that the L =0 cross section provides a relatively mode1-independent measure of Gamow-Teller strength. An understanding of the large L =2 cross sections observed in heavy-ion-induced reactions is achieved. Specific application is made to the (' C, ' B) reaction at E/A =70 MeV.PACS number(s): 25.70.Hi

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Energy dependence of the ratio of isovector effective interaction strengths|JστJτ|

Cited by 60 publications

References 23 publications

Gamow-Teller Strength Function inGe71via the (p, n) Reaction at M

Gamow-Teller Strength Function inGe71via the (p, n) Reaction at M

Nucleon charge-exchange reactions at intermediate energies

Heavy-ion charge-exchange reactions and the measurement of Gamow-Teller strength

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