Nuclear Structure properties significant to neutrinoless double beta decay of 124^{124}Sn

International audienceThe decay rate of neutrinoless double beta process is expected to give the first direct measure of the neutrino mass, if the corresponding nuclear matrix element can be reliably calculated [1]. A major complication in extracting the neutrino mass from the half-life of this decay is the uncertainty in the nuclear matrix element. There are certain experimental observable that may be placed to constrain the calculations of the matrix element [2]. One of the main ingredients in calculating the nuclear matrix element is the wave functions of the initial and final states, which are usually calculated based on different nuclear models [1, 2]. Single-nucleon transfer reactions can be used to probe the occupancy and vacancy of valence orbitals which can help to characterize the ground-state wave functions. The precise measurement of both neutron addition and removal cross-sections can be used to determine the occupation of valence orbits relevant to 0ν2β-decay, following the Macfarlane and French sum rules [3]. The method consists of requiring a normalization such that for a given orbit characterized by total angular momentum j, the sum of the measured occupancy and vacancy on the same target add up to the degeneracy of the orbit 2j+1. It has been shown that such measurements allowed for a detailed description of the energy and vacancy of the valence orbitals of 76Ge and 76Se, where 76Ge is a candidate for 0ν2βdecay. The results indicated that the Fermi surface is much more diffuse than in theoretical calculations [4]. Similar measurements have been recently performed on 130Te and 130Xe [5]. Both 76Ge and 130Te are subject of research for 0ν2β-decay programs known as GERDA, Majorana (for 76Ge) and CUORE (for 130Te). The present work is aimed to study neutron pickup and stripping transfer cross-sections on one of the 0ν2β-decay candidate 124Sn and its daughter 124Te. This nucleus is the focus of neutrino-less double beta decay study, at the upcoming underground India based Neutrino Observatory (INO). This information will be useful for constraining calculations of the nuclear matrix element for the 0ν2β-decay of 124Sn

Neutron transfer reactions to constrain Matrix element of neutrinoless double beta decay of 124^{124}Sn

International audienceNeutrinoless double beta decay (NDBD) is expected to give the first direct measure of the effective neutrino mass.The uncertainty in the latter will be dominated by that in the relevant nuclear matrix element (NME) [1]. Of the various observables that could be used to constrain the NME, the occupancy and vacancy of ground state wavefunctions of the parent and daughter nuclei involved in NDBD, are important ingredients [1, 2]. Single-nucleon transfer reaction cross-sections can be used for this purpose, making use of the Macfarlane and French sum rules [3

Occupation probabilities of valence orbitals relevant to neutrinoless double β\beta decay of 124^{124}Sn

International audienceNeutron transfer reaction measurements, relevant to the neutrinoless double β decay candidate Sn124 and its daughter Te124, have been performed. Precise measurements of both neutron addition [(d,p),(He4,He3)] and removal [(p,d),(He3,He4)] cross sections have been used to determine the occupation of valence orbitals pertinent to neutrinoless double β decay in these two nuclei. This information could be used to constrain calculations of the nuclear matrix element for the neutrinoless double β decay of Sn124. The change in the ground-state neutron vacancies in proceeding from Sn124 to Te124 is mainly found in the d3/2,5/2 and h11/2 orbitals. The occupancies of states near the Fermi level are in reasonable agreement with shell model calculations