Structure of excited states Seen in double beta decay investigated with the 148Nd(3He, nγ)150Sm and 98Mo(3He, nγ)100Ru two proton stripping reactions.

Abstract

ENGLISH ABSTRACT: The two proton transfer reaction (3He, nγ) has been measured on two targets 98Mo and 148Nd. High resolution data were taken using the neutron time of flight method and a wall of six NE102A plastic scintillator trigger detectors. These were operated in coincidence with the AFRODITE HPGe detector array to detect the γ-rays that originates from 100Ru and 150Sm. Thus made it possible to investigate the validity of the BCS proton pair stripping approximations. That is assumed in the nuclear matrix element calculations of the QRPA based models, for decays to the ground states of the candidate 0νββ nuclei. A strong proton pair stripping L = 0 transition to the I π = 0+2 spin state of 100Ru has been observed, while non were found for the case of 150Sm due to technical problems. This indicate a breakdown of the BCS proton pairing description in the ground state of 100Ru. In addition the low-lying spin members (I π = 2+1 , 4+1 , 6+1 and 8+1 ) of the yrast bands of both nuclei are clearly visible. Their population are attributed to the single neutron fusion evaporation channels.

AFRIKAANSE OPSOMMING: Die twee proton direkte oordrag reaksie (3He, nγ) was uitgevoer op die 98Mo soveel as op die 148Nd teiken kerne. Hoe resolusie γ-stralings meetings was waargeneem met die AFRODITE spektrometer in kominasie met die NE102A plastiek sintillator detektore. Waar die laas genoemde detektore gebruik was om die neutrone op te neem deur middel van die vlieg tyd metode. Hierdie metode het dit moontlike gemaak om die geldigeheid van die BCS proton paar oordrag benadering, wat in die QRPA modelle vir die grond toestand oorgegange wat vir die 0νββ kandidaat kerne van 100Ru en 150Sm aanvaar word te ondersoek. n Sterk proton paar L = 0 oordrag na die opgewekte Iπ = 0+2 vlak van 100Ru was wargeneem, maar geen soortgelyke oorgang was gewas waargeneem vir die 150Sm kern, as gevolge van tegniese redes. Die 100Ru waarneeming stel voor n afbreek van die BCS proton paar oordrag aanname. Verder die opgewekte toestande (I π = 2+1 , 4+1 , 6+1 en 8+1 ) van beide kerne was duidelike waargeneem tydens die meetings, dit word toegeskrywe aan kern saammesmelting.