Cryo OnlineMultidetector for Physics And Chemistry of Transactinides
Photo: G. Otto / GSI
The Cryo OnlineMultidetector for Physics And Chemistry of Transactinides (COMPACT) is a gas chromatography setup suitable for investigations of the interaction strength of short-lived single radioactive species with different bulk materials. Its rectangular chromatography channel is formed by two arrays (32 cm long and 1 cm wide), comprising 32 PIN diodes suitable for registering α particles and fission fragments emitted from species that decay inside the channel. The surface of the silicon PIN diodes is covered by a thin layer of adsorbent material, e.g., SiO2 or Au. The array can be operated in an isothermal chromatography regime at a constant temperature (e.g., room temperature).
Alternatively, a negative temperature gradient can be applied through a liquid nitrogen cryostat at the end of the channel (thermochromatography regime).
A combination of several COMPACT detectors with different adsorbents and in a wide temperature range allows comparative studies of elements of different volatilities/reactivities in one experiment. A high detection efficiency for α decay (~80%) and spontaneous fission (~100%) and a low detector rate in COMPACT behind the TASCA separator make possible highly sensitive experiments with volatile transactinide species at an one-atom-at-the-time level.