FLEROV LABORATORY of NUCLEAR REACTIONS

Seminar of physics sectors

Date and Time: Wednesday, 9 November 2016, at 3.30 pm

Venue: Conference hall, Flerov Laboratory of Nuclear Reactions

Seminar topic: «Effect of shell closure N=50 and N=82 on the structure of very neutron-rich nuclei. Measurements of neutron emission probabilities and half lives of nuclei at astrophysical r-process path»

Speaker: D. Testov

Abstract:

The report discusses the role of neutron excess in the β-decay of neutron-rich nuclei far from stability in the regions where the neutron decay channel becomes especially strong. To perform investigation of such nuclei we designed and built a devoted multi-detector system. It consists, first of all, of high-effective 4π neutron array TETRA which contains 80 counters of ³He constructed at JINR Dubna. Application of such a powerful neuron detector to study β-decay properties is essential. The system is also equipped with a 4π β-detector and a detector HPGe of γ-rays to enable coincidence between β-γ and neutron radiation detected simultaneously. Neutron-rich nuclei of interest were synthesized using the ISOL method. Experiments were carried out in collaboration with JINR (Dubna) at the accelerator complex ALTO IPN (Orsay, France). It is discussed the results of a few experimental campaigns conducted to investigate β-decay properties of neutron rich nuclei in the vicinity of the neutron closed shells N=50, N=82. It was measured half-lives of ^80,82,83,84Ga, ^123-125Ag, ^92-100Rb and probabilities of β-delayed neutron emission. We were the first ones to observe the structure of 81,82Ge via β-neutron gated γ-spectra and detection channel the absolute intensities of β-decay were proposed. For the first time the β-delayed neutron emission was observed for ¹²⁶Cd.