LABORATORI NAZIONALI DI LEGNARO
Nuclei with a large N/Z ratio in this area of the table of isotopes are of great interest to test nuclear models and provide information about single particle states. During the last two decades there has been a substantial effort directed to gathering information about the region around the neutron-rich 132Sn [1-3], the most exotic doubly-magic nucleus presently at reach. The 132Sn isotope is itself a very interesting case [4]. The simplest excited levels correspond with particle-hole states where a particle is excited across the energy gap of the closed shell. The identification of the multiplets, which arise from those particle-hole states, provides information on the nuclear two-body elements. This isotope has been studied in detail through the beta-decay of 132In [5]. Nevertheless, a lot of the expected particle-hole multiplet states remained unidentified. We have used fast-timing and gamma spectroscopy to investigate 132Sn. The experiment was carried out at the ISOLDE facility, where the excited states of 132Sn were populated in the beta-decay of In isomers, produced in a UCx target unit equipped with a neutron converter. The In isomers were ionized using the ISOLDE Resonance Ionization Laser Ion Source (RILIS), which for the first time allowed isomer-selective ionization of indium. The measurements took place at the new ISOLDE Decay Station (IDS), equipped with four highly efficient clover-type Ge detectors, along with a compact fast-timing setup consisting of two LaBr3(Ce) detectors and a fast beta detector. The setup incorporated a tape transport system to remove longer-lived activities. In this work we report on the excited structure of 132Sn, populated in the beta-decay of 132In, and also, owing to the RILIS isomer selectivity, separately from the beta-n decay of the 133In 1/2- isomer and 133In 9/2+ the ground state. We present preliminary results with a new level-scheme, which have been enlarged with 13 new levels and more than 40 new γ-transitions. These results are completed with new measurements of the lifetimes of 132Sn excited states.

DATA: 27-06-2019