A novel current mode operating beam counter based on not preamplified HPDs

TL;DR

This paper introduces a new current mode beam counter using proximity focused HPDs without preamplifiers, capable of monitoring antiproton beams with high precision and stability in a magnetic field.

Contribution

The novel beam counter operates parasitically in current mode with high dynamic range and stability, even in stray magnetic fields, and is calibrated through two independent methods.

Findings

Operates effectively in stray magnetic fields of the ATHENA magnet.

Achieves gain variation from zero to thousands with 0.1% precision.

Demonstrates linearity and stability up to 100 nC charge response.

Abstract

A novel system to monitor the intensity and the stability of a bunched beam of $\simeq 1.2\times 10^{7}$ antiprotons ($\bar{p}$s) with a length of $\simeq$ 250 ns (FWHM) and to measure its trapping efficiency in a Penning trap is described. This system operates parasitically detecting the pions from the annihilation of part of the beam in a degrader. Six plastic scintillators have been coupled from one side to six proximity focused HPDs without preamplifiers and operating in current mode. This device works in the stray field of the ATHENA magnet with no loss of efficiency; the gain can be varied from zero to a few thousands with a precision better than 0.1% and the dynamic range is larger than 8 orders of magnitude. Linearity and stability have been measured up to charge responses of 100 nC, corresponding to the beam completely dumped. The beam counter has been calibrated in two different and independent ways giving consistent results.