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

Abstract

A novel system to monitor the intensity and the stability of a bunched beam of ≃ 1.2 × 10 7 antiprotons (ps) with a length of ≃ 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.

Temporally Controlled Modulation of Antihydrogen Production and the Temperature Scaling of Antiproton-Positron Recombination

“…The ATHENA antihydrogen apparatus [13], located at the Antiproton Decelerator (AD) facility at CERN, consisted of several modular components, including p and mixing traps (both held at 15 K in a 3 T solenoid field), the e accumulator [14], a Si vertex detector [15,16], external detectors [17] and the associated control systems.…”

Particle Physics Aspects of Antihydrogen Studies with ALPHA at CERN

“…We are currently investigating the possibility of a new beam detector based on a CVD diamond film, with even smaller thickness and improved spatial resolution. The antiproton beam intensity is measured with a scintillator coupled to a hybrid photodiode, a system similar to that discussed in [36].…”

The ATHENA antihydrogen apparatus

“…The external beam detectors monitor annihilation on the degraders (Fig.2). They consist of two types of modules, Front and Barrel, both made from 1 cm thick Bicron BC408 plastic scintillators [12]. The two Front detectors are (195 × 100) mm 2 each and the two Barrel detectors are (800 × 195) mm 2 each.…”

“…We used two different models of HPD's built by DEP [16] namely model PP0350F for the Front and model PP0350D the for the Barrel detector. A detailed description of their characteristics can be found elsewhere [12].…”

“…The half life of 24 Na * is 15 h. We dumped the antiproton beam in an aluminum target (made of four foils with a thickness of 110 µm, glued together) located at the entrance of the ATHENA beam pipe. Using the induced activity, measured off-line with a calibrated germanium detector, an average beam intensity per shot of (1.20 ± 0.19) × 10 7p was obtained [12]. As an independent measure of beam intensity, the number of antiprotons in the AD ring was measured before extraction by a low noise Schottky pickup probe [19,20].…”