Non-perturbative measurement of low-intensity charged particle beams

Abstract

Non-perturbative measurements of low-intensity charged particle beams are particularly challenging to 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 rings at CERN, an absolute measurement of the beam intensity is essential to monitor the operation efficiency. Superconducting quantum interference device (SQUID) based cryogenic current comparators (CCC) have been used for measuring slow charged beams in the nA range, showing a very good current resolution. But these were unable to measure fast bunched beams, due to the slew-rate limitation of SQUID devices and presented a strong susceptibility to external perturbations. Here, we present a CCC system developed for the AD machine, which was optimised in terms of its current resolution, system stability, ability to cope with short bunched beams, and immunity to mechanical vibrations. This paper presents the monitor design and the first results from measurements with a low energy antiproton beam obtained in the AD in 2015. These are the first CCC beam current measurements ever performed in a synchrotron machine with both coasting and short bunched beams. It is shown that the system is able to stably measure the AD beam throughout the entire cycle, with a current resolution of .

Beam Diagnostics for Low Energy Antiprotons

“…3 [16]. These are the first CCC beam current measurements performed in a synchrotron using both, coasting and short-bunched beams.…”

Numerical analysis of a folded superconducting coaxial shield for cryogenic current comparators

“…Ring shield CCCs are commonly applied in diagnostic devices of particle beams in accelerator facilities [9][10][11][12]. shielding configuration exhibits an interleaved comb-like meander structure along the axial direction, as depicted in Figures 12 and 13.…”

“…In this work, we investigate the performance of a folded coaxial shield (depicted in Figures 1b and 1c), which is, to the best of our knowledge, studied here for the first time. This shield configuration is compared to the ring structure (depicted in Figure 1a) found in several CCCs dedicated to the diagnostics of particle beams in accelerator facilities [9][10][11][12]. In this comparison, the shields geometries are constrained by the radius of the beam tube and the cross-sectional area of the CCC pickup core.…”

Coreless SQUID-based cryogenic current comparator for non-destructive intensity diagnostics of charged particle beams

“…However, recent experiments have shown that even the white noise is limited by dissipative effects in the core material. Moreover, a tight coupling of the input coil comes along with a large susceptibility to disturbances as well as huge demands on the dynamic range and current slew-rate of the beam monitor [9].…”