Systematic study of nuclear β decay

Homma, Hiroyuki; Bender, E.; Hirsch, Martin; Muto, K.; Klapdor‐Kleingrothaus, H. V.; Oda, Takuya

doi:10.1103/physrevc.54.2972

Cited by 145 publications

(225 citation statements)

References 26 publications

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“…Then, we study the sensitivity of the matrix elements M GT 2ν to the nuclear deformation and to the pp strength, which is known to be a suppression mechanism. In the case of HF we reproduce simultaneously this information using coupling strengths χ ph GT = 0.1 MeV and κ pp GT = 6/A MeV, while in the case of WS we find that the parametrization of Homma [3], χ ph GT = 5.2/A 0.7 MeV and κ pp GT = 0.58/A 0.7 MeV, reproduces better the experiment. As an example, we show in Fig.…”

mentioning

confidence: 59%

Effect of deformation on two-neutrino double beta decay matrix elements

Álvarez-Rodríguez

Sarriguren

Guerra

et al. 2006

Progress in Particle and Nuclear Physics

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We study the effect of deformation on the two-neutrino double beta decay for ground state to ground state transitions in all the nuclei whose half-lives have been measured. Our theoretical framework is a deformed QRPA based in Woods-Saxon or Hartree-Fock mean fields. We are able to reproduce at the same time the main characteristics of the two single beta branches, as well as the double beta matrix elements. We find a suppression of the double beta matrix element with respect to the spherical case when the parent and daughter nuclei have different deformations.It has been observed that the matrix elements M 2ν in all the measured 2ν ββ cases for the 0 + → 0 + transition are quenched with respect to those predicted from pure quasiparticle transitions. The physical mechanisms responsible for this reduction have been a subject of great interest. In this work, we study the effect of the parent and daughter deformations on the M 2ν matrix elements.We use a deformaed quasiparticle random phase approximation (pnQRPA) to describe simultaneously the energy distributions of the single β Gamow-Teller (GT) strength and the matrix element M 2ν of all the double beta emitters whose half-lives have been measured: 48 Ca, 76 Ge, 82 Se, 96 Zr, 100 Mo, 116 Cd, 128 Te, 130 Te, 136 Xe, and 150 Nd. The formalism includes a deformed quasiparticle basis and residual spin-isospin separable interactions in both particle-hole (ph) and particle-particle (pp) channels. We consider two different deformed mean fields: a phenomenological Woods-Saxon (WS) potential and a selfconsistent Hartree-Fock (HF) with Skyrme interactions [1]. While the deformation in the HF calculation is obtained selfconsistently, in the WS case it is an input parameter taken to reproduce the experimental quadrupole moments.We describe the 2ν ββ process as two successive GT transitions via intermediate 1 + states,1

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mentioning

confidence: 59%

Effect of deformation on two-neutrino double beta decay matrix elements

Álvarez-Rodríguez

Sarriguren

Guerra

et al. 2006

Progress in Particle and Nuclear Physics

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“…As we shall see in the next section, the strengths from Ref. [8] reproduce well the data when using the WS potential, but one needs a somewhat smaller value of GT ph to reproduce the GT resonance with the HF mean field. We introduce the proton-neutron QRPA phonon operator for GT excitations in even-even nuclei,…”

Section: Brief Description Of the Theorymentioning

confidence: 71%

“…This fitting procedure was systematically carried out in Ref. [8], where the strengths GT ph and GT pp were considered to be smooth functions of the mass number A. The result found using a Nilsson potential as the deformed mean field was GT ph = 5.2/ A 0.7 MeV and GT pp = 0.58/ A 0.7 MeV.…”

Section: Brief Description Of the Theorymentioning

confidence: 99%

“…[6], where a Nilsson potential was used to generate single-particle orbitals. Subsequent extensions including Woods-Saxon type potentials [7], residual interactions in the particle-particle channel [8], selfconsistent deformed Hartree-Fock (HF) mean fields with consistent residual interactions [9], and self-consistent approaches in spherical neutron-rich nuclei [10], can also be found in the literature. In Refs.…”

Section: Introductionmentioning

confidence: 99%

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Deformed quasiparticle random phase approximation formalism for single- and two-neutrino doubleβdecay

et al. 2004

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We use a deformed quasiparticle random phase approximation formalism to describe simultaneously the energy distributions of the single ␤ Gamow-Teller strength and the two-neutrino double ␤ decay matrix elements. Calculations are performed in a series of double ␤ decay partners with A = 48, 76, 82, 96, 100, 116, 128, 130, 136, and 150, using deformed Woods-Saxon potentials and deformed Skyrme Hartree-Fock mean fields. The formalism includes a quasiparticle deformed basis and residual spin-isospin forces in the particlehole and particle-particle channels. We discuss the sensitivity of the parent and daughter Gamow-Teller strength distributions in single ␤ decay, as well as the sensitivity of the double ␤ decay matrix elements to the deformed mean field and to the residual interactions. Nuclear deformation is found to be a mechanism of suppression of the two-neutrino double ␤ decay. The double ␤ decay matrix elements are found to have maximum values for about equal deformations of parent and daughter nuclei. They decrease rapidly when differences in deformations increase. We remark on the importance of a proper simultaneous description of both double ␤ decay and single Gamow-Teller strength distributions. Finally, we conclude that for further progress in the field, it would be useful to improve and complete the experimental information on the studied Gamow-Teller strengths and nuclear deformations.

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“…This implies that the particle-particle interaction in the protonneutron channel is in principle undetermined. Therefore the 054308-2 coupling constant κ GT pp is fitted to the phenomenology, as for example to reproduce half-lives as is usually done [17,18].…”

Section: Theoretical Frameworkmentioning

confidence: 99%

Gamow-Teller strength distributions in Xe isotopes

Moreno

Álvarez-Rodríguez²,

Sarriguren³

et al. 2006

Phys. Rev. C

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The energy distributions of the Gamow-Teller (GT) strength are studied for even-even Xe isotopes with mass numbers from 124 to 142. A self-consistent microscopic formalism is used to generate the single-particle basis, using a deformed Skyrme Hartree-Fock mean field with pairing correlations in the BCS approximation. The GT transitions are obtained within a quasiparticle random phase approximation approach using a residual spin-isospin interaction in the particle-hole (ph) and particle-particle (pp) channels. We then discuss the pairing BCS treatment and the determination of the ph and pp residual interaction coupling constants. We study the GT + and GT − strength distributions for the equilibrium nuclear shapes, which comprise essential information for studies of charge-exchange reactions and double-β processes involving these isotopes.

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Systematic study of nuclear β decay

Cited by 145 publications

References 26 publications

Effect of deformation on two-neutrino double beta decay matrix elements

Effect of deformation on two-neutrino double beta decay matrix elements

Deformed quasiparticle random phase approximation formalism for single- and two-neutrino doubleβdecay

Gamow-Teller strength distributions in Xe isotopes

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