A GAS TARGET SYSTEM FOR CONTINUOUS PRODUCTION AND RAPID ISOLATION OF THE SHORT-LIVED RADIOISOTOPE 35Ar

摘要

This paper contains a detailed description of the design and operation of a continuous flow gas target system used for the production and isolation of 35Ar. Vaporous CC14 is used as the target material for the reaction 35Cl(p,n) 35Ar. In subsequent stages the 35Ar is separated from the carrier gas CC14 and transported to a shielded region where the decay 35Ar(β+) 35 Cl is studied.[1]nThe major interest in this mirror decay is to determine accurately the weakninteraction vector coupling constant for comparison with the values obtainednfrom decays between members of J=0+ , T=1 isobaric triplets [2] . The experimental quantities needed are (l) the 35 Cl(p,n) 35 Ar threshold energy;(2) the 35 Ar half life;(3) the ratios of the three positon branches and (4) the spatial asymmetry of positons emitted from nuclear spin polarized 35 Ar. The last quantity (4) was measured in the U.S.A. by Calaprice et al. [[3]] • The first two can be adequately measured from solid targets of KC1 [1,4J . The branching ratios are measured byncomparing the relative intensities of the 511 keVγ-rays from positon annihilationnand the 1220 and 1762 keV y rays from the excited state branches (figure 1).