Advances Toward and Beyond the Proton Drip line with Recoil-Isomer Tagging

摘要

This paper reviews the past, present and future status of recoil-isomer tagging at the University of Jyvaskyla. The main focus of this research has been to access isomeric states at and beyond the mass ≈ 140 proton drip line. Recoil-isomer tagging was first used at the University of Jyvaskyla in 1998 to establish the prompt rotational band built upon a K~π = 8– isomeric state in 138Gd. Since that time a series of experiments have been performed which have studied isomeric states in the N = 77 isotones _65~140Eu77, _65~142Tb77 and _67~144Ho_77, and in the N = 74 K-isomer chain, _64~138Gd74 and _66~140 Dy74. These experiments have revealed valuable first information about deformations, single-particle excitation energies and hindrance factors in nuclei at and beyond the proton drip line where little or no information previously existed.The results of the most-recent experiments were discussed. These experiments established new isomeric states in Dy77, Pm75, and Gd73 and a further two isomers which are currently unplaced. The paper concludes with a discussion of the future prospects for this research including the increased efficiency of the recoil-isomer tagging technique with a new Multi-Wire Proportional Counter (MWPC) detector which was designed and built at the University of Manchester. The first results from this new setup were shown.