Study of the N=50 shell closure close to 78Ni

Abstract

The PARRNe (Production d'Atomes Radioactifs Riches en Neutrons) experimental program has been part of the recent R&D efforts for the design of the SPIRAL2 project at GANIL. The PARRNe2 set-up installed at IPNOrsay allows the use of the Tandem as a deuteron driver in order to produce mass separated fission fragment beams. The measured fission fragment yields proved to be high enough to undertake a series of β-decay experiments dedicated at studying the structure of proton-deficient nuclei close to N=50. We report here on two such experiments, the first being dedicated at the observation of the decay of 83 Ga→ 83 Ge (Z=32, N=51), 84 Ga→ 84 Ge (Z=32, N=52) and the second of the decay of 81 Zn→ 81 Ga (Z=31, N=50) allowing for the fist time the identification of a few γ lines with transitions in the daughter nuclei thus providing the material for a preliminary glimpse of their structure.

Progress in ISOL target–ion source systems

“…No serious damage was detected so far when operating a standard ISOLDE TISS for more than a week with sulfur addition. t r = 0.065 s and t f = 5.9 s (plus a small slow component: a = 0.988 and t s = 50 s) 3 . This shows that the faster effusion of SnS versus Sn does not outweigh the slower diffusion due to the lower target temperature.…”

“…ISOL beams of zinc isotopes ranging from 57 Zn [1] to 81 Zn [2][3][4] have been produced and used for decay spectroscopy experiments. An important breakthrough towards pure ISOL beams had been achieved with the use of the resonance ionization laser ion source (RILIS) [5][6][7].…”

“…Thus, for Zn ionization with the RILIS, the most serious background will be Rb and, to less degree also Ga and Sr. In the mentioned decay spectroscopy experiments either selective detection methods (beta-delayed neutrons in [2]) and/ or an identification via the time behaviour or ''laser on"/ ''laser off" differences respectively and a removal of longlived background by a tape system [3,4] were employed. However, new applications of RIBs include direct precision mass measurements with a Penning trap and experiments with post-accelerated beams like e.g.…”

Ucx target developments for the ALTO and the SPIRAL 2 projects

“…The PARRNe set up has already enabled R&D studies on UC x targets for the SPIRAL 2 project, using the 26 MeV/1 mA deuteron beam, delivered by the Tandem, to produce fast neutrons [2]. Physics experiments were also performed [3]. An electron accelerator connected with the PARRNe separator is being constructed [4].…”

“…UCx target 14 mm diam., 100 mm length, density 3.6 g/cm 3 obtain a homogeneous temperature of the target for a long duration (3 months). Some temperature measurements are done in different places to know the spatial distribution of temperature in the target.…”