Level structure of 92Rh: Implications for the Two-proton Decay of 94mAg

The 21+ isomer in 94Ag has recently been reported to have a two-proton decay branch to 92Rh. We have populated 92Rh through the 40Ca(58Ni,alphapn) reaction at 240 MeV, and have performed detailed spectroscopic measurements of the levels, finding new states and measuring angular distributions of gamma rays. We find no evidence for the states reported to be populated by the two-proton decay of 94Agm. The calculated Q-value for the two-proton decay implies that this process directly feeds low-lying yrast, or near-yrast, states in 92Rh, which is very difficult to reconcile with our observations. Several scenarios for the population of 92Rh are discussed, none of which appears to be satisfactory

''Neutron Shell'': a high efficiency array of neutron detectors for g-ray spectroscopic studies with Gammasphere

Abstract A shell of neutron detectors was designed, constructed, and employed in g-ray spectroscopy with Gammasphere. It consists of up to 35 tapered regular hexagons that replace the same number of forward Ge-detector modules in Gammasphere. The shell was designed for high detection efficiency and very good neutron-g discrimination. The simultaneous use of time-of-flight, and two methods of pulse shape discrimination between neutrons and g rays is described. Techniques for spectroscopy with efficient detection of two neutrons are discussed.

Prompt Proton Decay in the Vicinity of 56Ni

A new decay mode, the so called prompt proton decay, was discovered in 1998. It has since proven to be an important decay mechanism for several neutron deficient nuclei in the A similar to 60 region. To measure with high accuracy the energies and angular distributions of these protons, a state-of-the-art charged particle detector - LuWuSiA - was developed. It was first utilized during a fusion-evaporation reaction experiment performed at Argonne National Laboratory, U.S.A. In this contribution, the characteristics of the prompt proton decay are discussed along with the special features of LuWuSiA as well as a revisit to the prompt proton decay in Cu-58

Comprehensive Gamma-ray Spectroscopy of Rotational Bands in the N=Z+1 Nucleus 61Zn

The Zn-61(30)31 nucleus has been studied via the combined data of two fusion-evaporation reaction experiments using a Ar-36 beam and a Si-28 target foil. The experimental setups involved the Ge array GAMMASPHERE and neutron and charged particle detectors placed around the target position. The resulting level scheme comprises about 120 excited states connected via some 180 gamma-ray transitions. In total, seven rotational structures were identified up to I similar to 25 or higher and compared with predictions from cranked Nilsson-Strutinsky calculations

Thorough Gamma-ray and Particle Decay Investigations of 58Ni

The combined data from three fusion-evaporation reaction experiments have been utilized to investigate the semi-magic nucleus Ni-58(28)30. To detect gamma rays in coincidence with evaporated particles, the Ge-detector array Gammasphere was used in conjunction with the charged-particle detectors Microball and LuWuSiA (the Lund Washington University Silicon Array), and a neutron detector array. The results yield a significantly extended level scheme of Ni-58 comprising some 340 gamma-ray transitions and include a total of at least 14 discrete particle decays into excited states of the daughter nuclei Fe-54 and Co-57. The level scheme is compared with large-scale shell-model calculations and cranked Nilsson-Strutinsky calculations

Extensive γ-ray spectroscopy of normally and superdeformed structures in 61 29 Cu 32

Cu. In addition to the Ge array GAMMASPHERE, neutron and charged-particle detectors placed around the target position were used for high-performance particle spectroscopy. The constructed level scheme includes more than 160 energy levels and 320 γ-ray transitions belonging to both normally deformed as well as superdeformed rotational structures. The multipolarities have been determined for the γ-ray transitions and as a result spin-parity assignments are given for nearly all energy levels. Experimental results in the normally deformed region are compared with predictions from large-scale shell model calculations