Cryogenic Design and Thermal Analysis of the CURIE CryoTrap

Abstract

The decay rates of electron capture (EC) radioisotopes, such as 7Be, are demonstrativelysusceptible to alteration with change to the electron orbital structure [1] [2] [3] [4]. The Cryogenic Ultra-high vacuum Radioactive Isotope Experiment (CURIE) Project aims to isolate the various charge states of the low-Z radioisotope 7Be stably to perform novel half-life measurements. To achieve this, the system must be cooled to 4K to reach extreme high vacuum (XHV) conditions in excess of 10E−15 mbar and to ensure single ion resolution detection. The cryogenic design which achieves this is presented here. The design consists of the actively cooled 45K radiation shield, and the 4K stage which houses the Penning trap. The 4K stage is brought to XHV and maintained at these pressures through the design of a rotary “cryovalve”. This thesis details the entire apparatus, the heat loads incident on both stages through simulation, and outlines an experimental method for testing the “cryovalve”.