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.
Cryogenic Current Comparator for Storage Rings and Accelerators
A Cryogenic Current Comparator (CCC) was developed for a non-destructive, highly sensitive monitoring of nA beams at the planned FAIR accelerator facility at GSI. The sensor part of the CCC was optimized for lowest possible noise-limited current resolution in combination with a high system bandwidth of about 200 kHz. It is foreseen to install the CCC inside the CRYRING, which will act as a well-suited test bench for further optimization of the CCC performance and the cryostat. In the meantime until the completion of CRYRING a CCC has been installed and will be tested in the antiproton storage ring (Antiproton Decelerator AD) at CERN. The pulse shape in the AD requires dedicated optimization of the sensor time response. The beam current will increase rapidly during injection from 0 to 12 μA. Since the slew rate of the overall system is limited by the CCC pickup coil, the input signal has to be low-pass filtered to not exceed the slew rate of the CCC system and to ensure a stable operation. For this purpose different low-pass configurations had been tested. In this contribution we present results of the CCC sensor for AD, CRYRING and FAIR, respectively.
A cryogenic current-measuring device with nano-ampere resolution at the storage ring TARN II
Abstract In cooler-ring experiments, an accurate and non-destructive current measurement is essential for determining the reaction cross sections. The lowest current which can be measured by the DC current transformer commonly used so far is some μA. In order to measure a low-beam current from nA to μA, we made a cryogenic current-measuring device using a superconducting quantum interference devices (SQUID), and measured the circulating ion current at the cooler ring TARN II. This paper gives the design and performance of the device.