Many-body cascade calculation of final state interactions in 12C nonmesonic weak decay

I. GONZALEZ; C. BARBERO; A. DEPPMAN; S. DUARTE; F. KRMPOTIC; O. RODRIGUEZ

JOURNAL OF PHYSICS G. NUCLEAR PHYSICS

IOP PUBLISHING LTD

Año: 2011 vol. 38 p. 1 - 16

0305-4616

We study the nonmesonic weak decay (NMWD) N → nN of 12C hypernucleus induced by one nucleon N = n, p. The whole process is described by two coupled models: one for the primary NMWD of hyperon in the nuclear environment, and the other taking into account the final state interactions (FSI) of the two outgoing nucleons within the residual nucleus. The NMWD dynamics is represented by the one-meson-exchange potential with usual parametrization, while the independent-particle shell model is used as the nuclear structure framework. The FSI are accounted for by a time-dependent multicollisional Monte Carlo cascade scheme, implemented within the CRISP code (Collaboration Rio-S˜ao Paulo), which describes in a phenomenological way both the nucleon–nucleon scattering inside the nucleus and the escaping of nucleons from the nuclear surface. An evaporation phase is included to cool down the cascade residual nucleus as well. We analyze the singlenucleon kinetic energy spectra, and the two-nucleon coincidence spectra as a function of both: (i) the sum of the kinetic energies and (ii) the opening angle. The theoretical results are compared with recent data from KEK and FINUDA experiments, obtaining fairly good agreement for inclusive and exclusive kinetic energy spectra. Further theoretical improvements are required to explain angular distributions.N → nN of 12C hypernucleus induced by one nucleon N = n, p. The whole process is described by two coupled models: one for the primary NMWD of hyperon in the nuclear environment, and the other taking into account the final state interactions (FSI) of the two outgoing nucleons within the residual nucleus. The NMWD dynamics is represented by the one-meson-exchange potential with usual parametrization, while the independent-particle shell model is used as the nuclear structure framework. The FSI are accounted for by a time-dependent multicollisional Monte Carlo cascade scheme, implemented within the CRISP code (Collaboration Rio-S˜ao Paulo), which describes in a phenomenological way both the nucleon–nucleon scattering inside the nucleus and the escaping of nucleons from the nuclear surface. An evaporation phase is included to cool down the cascade residual nucleus as well. We analyze the singlenucleon kinetic energy spectra, and the two-nucleon coincidence spectra as a function of both: (i) the sum of the kinetic energies and (ii) the opening angle. The theoretical results are compared with recent data from KEK and FINUDA experiments, obtaining fairly good agreement for inclusive and exclusive kinetic energy spectra. Further theoretical improvements are required to explain angular distributions.