Cryogenic Current Comparators for Larger Beamlines
The new version of a cryogenic current comparator with eXtended dimensions (CCC-XD) for the beam monitoring of charged particles, which is currently in the optimization cycle, is presented herein. The CCC-XD is designed for a nondestructive, highly sensitive monitoring of a few nA beam intensities for 150-mm beamline diameters at the Facility for Antiproton and Ion Research at GSI (Helmholtz Center of Heavy Ion Research). The new CCC comprises a combined superconducting pickup loop, a magnetic shield, and a ferrite core with superconducting quantum interference device based readout. Compared to the previous CCC currently running at CERN, the niobium shield exhibits enlarged geometric dimensions, which results in a more effective suppression of magnetic stray fields from the beamline environment. First results of laboratory measurements as well as simulations of the electrical behavior are presented in this paper. The CCC-XD system—in combination with a newly developed cryostat—will be ready for testing in the beamline of CRYRING at GSI in 2018.
Influence of Mechanical Deformations on the Performance of a Coaxial Shield for a Cryogenic Current Comparator
This article studies the impact of mechanical deformations on the performance of a coaxial-type cryogenic current comparator (CCC). Such deformations may become a concern as the size of the CCC increases (e.g., when used as a diagnostic device in a particle accelerator facility involving beamlines with a large diameter). In addition to static deformations, this article also discusses the effect of mechanical vibrations on the CCC performance.
Fundamental Limits on Squid Technology
In the last few years, the flux noise energy of the dc Superconducting Quantum Interference Device (SQUID) (Jaklevic et al., 1964) has been lowered by about four orders of magnitude. The most sensitive SQUID yet made is close to the limits set by fundamental quantum processes. The purpose of this article is to review these developments, and, in particular, to discuss at some length the limiting quantum processes in both single junctions and SQUIDs.