Lifetime measurements in 36Ar

Complete text of publication follows. The systematic study of the sd-shell nuclei were continued in the framework of a cooperation project between the Laboratories of the Helsinki University and ATOMKI. The goal of the studies was the 36Ar nucleus. Experimental data for 36Ar is lacking, the few known lifetimes of excited states are only poorly determined. There are great discrepancies in the previously reported lifetime values, especially for the short-living states (τ<100 fs). The present study was undertaken in order to clear the apparent discrepancy in the reported mean lifetime values,and to be able to further test the modern shell model in this mass region. The 35Cl(p, γ)36Ar radiative capture reaction was used for the measurements. In these reaction studies, the 1.2 to 2.0MeV proton beam with a typical intensity of 10μA was supplied by the 5 MV Van de Graaff accelerator of ATOMKI. The 35Cl target was implanted into thick Ta backing. The gamma-decay of four resonances were studies and their branching ratios were determined [1]. For the lifetime measurements the Doppler shift attenuation (DSA) method was applied using computer simulations with Monte Carlo method and experimental stopping power values. The evaluation of the lifetime values is in progress. In order to reduce the 19F(p,αγ)16O background the preparation of new set of implanted targets is under way in Helsinki