CERN, Geneva, Switzerland
The University of Liverpool, Liverpool, United Kingdom
HIJ, Jena, Germany
IOQ, Jena, Germany
GSI, Darmstadt, Germany
Cockcroft Institute, Warrington, Cheshire, United Kingdom
Non-perturbative measurement of low-intensity charged particle beams is particularly challenging for beam diagnostics due to the low amplitude of the induced electromagnetic fields. In the low-energy Antiproton Decelerator (AD) and the future Extra Low ENergy Antiproton (ELENA) rings at CERN, an absolute measurement of the beam intensity is essential to monitor operational efficiency and provide important calibration data for all AD experiments. Cryogenic Current Comparators (CCC) based on Superconducting QUantum Interference Device (SQUID) have in the past been used for the measurement of beams in the nA range, showing a very good current resolution. However these were unable to provide a measurement of short bunched beams, due to the slew-rate limitation of SQUID devices and their strong susceptibility to external perturbations. Here, we present the measurements and results obtained during 2016 with a CCC system developed for the Antiproton Decelerator, which has been optimized to overcome these earlier limitations in terms of current resolution, system stability, the ability to cope with short bunched beams, and immunity to mechanical vibrations.
FSU Jena, Jena, Germany
HIJ, Jena, Germany
GSI, Darmstadt, Germany
IPHT, Jena, Germany
IOQ, Jena, Germany
Supracon AG, Jena, Germany
A new Cryogenic Current Comparator with eXtended Dimensions (CCC-XD) is currently under development for a non-destructive, highly sensitive monitoring of nA-intensities of beams for larger beamline diameters planned for the new FAIR accelerator facility at GSI. The CCC consists of a superconducting coil which is read out by a Superconducting Quantum Interference Device (SQUID), a flux concentrator and a superconducting shield. The new flux concentrator comprises of a specially designed, highly permeable core made of nanocrystalline material in order to assure a low-noise operation and a high system bandwidth of up to 200 kHz. The superconducting shielding of niobium has extended geometric dimensions and will suppress disturbing magnetic fields of the beamline environment effectively. New SQUID sensors with sub-μm-Josephson junctions enable extreme low-noise signals and high disturbance-suppression. The CCC-XD system and the new dedicated cryostat will be ready for testing in the CRYRING at GSI in 2017. Results from electrical measurements with the components of the new CCC-XD Setup will be presented in this work.
GSI, Darmstadt, Germany
HIJ, Jena, Germany
IOQ, Jena, Germany
FSU Jena, Jena, Germany
After successful tests with the GSI-CCC prototype, measuring beam intensities down to 2nA at a bandwidth of 10 kHz, a new advanced Cryogenic Current Comparator system with extended geometry (CCC-XD) is under development. This system will be installed in the upcoming Cryring facility for further optimization, beam diagnostics and as an additional instrument for physics experiments. After the test phase in Cryring it is foreseen to build four additional CCC units for FAIR, where they will be installed in the HEBT lines and in the Collector Ring (CR). A universal cryostat has been designed to cope with the various boundary conditions at FAIR and at the same time to allow for uncomplicated access to the inner components. To realize this compact cryostat, the size of the superconducting magnetic shielding has to be minimized as well, without affecting its field attenuation properties. Hence detailed FEM simulations were performed to optimize the attenuation factor by variation of geometrical parameters of the shield. The beam tests results with the GSI-CCC prototype, and the developments for FAIR, as well as the results of simulation for magnetic shield optimization will be presented.