P. Mutti

New isomer in 96Y marking the onset of deformation at N = 57

The level scheme of 96Y was significantly extended and a new 201 ns isomer was located at 1655 keV excitation energy, with spin-parity assignment of 5± or 6−. The isomer decays to spherical low-spin structure by transitions with large hindrance and is fed by a short cascade which resembles the beginning of a rotational band. This is in analogy with the feeding and decay pattern of the 4− isomer in 98Y, here confirmed, by lifetime analysis, as a bandhead of a rotational structure with sizable deformation. It is suggested that the new isomer in 96Y arises from a shape change between deformed and spherical configurations, which indicates the appearance of deformation already at N = 57 in the yttrium chain. The experimental findings for 96Y are strengthened by theoretical calculations based on the complex Excited Vampir model.

Lifetime Measurements in Neutron-rich Xe Isotopes - Evolution of Quadrupole Collectivity Beyond

Picosecond lifetimes of excited states in neutron-rich Xe isotopes were measured at the Institut Laue- nLangevin via

^{132}

gamma

Sn

-ray spectroscopy of fission fragments from neutron-induced fission of 235U and 241Pu ntargets. The data collected with the recently installed fast timing array FATIMA in combination with nthe EXOGAM Ge array were analysed using the new generalized centroid difference method. Our naim is to study the quadrupole and octupole collectivity, arising in the mass region beyond the doubly nmagic 132Sn, by means of transition probabilities. These can be calculated from the directly measured nlifetimes.

First results of the (n,γ) EXILL campaigns at the Institut Laue Langevin using EXOGAM and FATIMA

At the PF1B cold neutron beam line at the Institut Laue Langevin the EXILL array consisting of EXOGAM, GASP and LOHENGRIN detectors was used to perform (n,γ) measurements under very high coincidence rates. About ten different reactions were then measured in autumn 2012. In spring 2013 the EXOGAM array was combined with 16 LaBr3(Ce) scintillators in the FATIMA@EXILL campaign for the measurement of lifetimes using the generalised centroid difference method. We report on the properties of both set-ups and present first results on Pt isotopes from both campaigns.