The beam test facility at Jefferson Lab for the precise energy measurement of future calorimeter concepts

TL;DR

This work presents the Jefferson Lab Hall D Pair Spectrometer as a beam-test facility for precise energy measurement of future calorimeter concepts. It leverages real-lepton beams in the $3-6\,\mathrm{GeV}/c$ range to study light collection, signal processing, and front-end electronics across PbWO$_4$ crystals with PMT and SiPM readouts, as well as SciGlass radiators. The PS enables energy tagging with an estimated precision of $<0.6\%$, and the authors report on the performance of numerous calorimeter prototypes, including detailed characterizations of linearity and threshold effects, as well as multi-module shower reconstruction. The results inform calorimeter design for current and future NP experiments, including environments with strong magnetic fields where SiPMs are favored, and establish PS-based beam testing as a valuable platform for calorimeter R&D.

Abstract

In experimental nuclear physics (NP), high-precision electromagnetic calorimetry typically requires a good energy resolution and linear photosensor response on the level of (1-2)% over a full dynamic range of the detector. The beam of secondary leptons at the Jefferson Lab experimental complex, provided by the Hall D pair spectrometer (PS), is an optimal facility for studies aiming to understand the impact of light collection and signal processing on calorimetry energy resolution under real experimental conditions. The light emission and collection processes depend on radiator component quality and type, while signal processing depends on photosensor type and front-end electronics design. Various calorimeter tower components and detector assemblies for current and future NP experiments were tested within the lepton momentum range of (3-6) GeV/c using PS. The energy resolution of the PS itself is estimated to be better than approximately 0.6%.

Figures (7)

• Figure 1: Pair Spectrometer in Hall D.
• Figure 2: Pair Spectrometer test stand for calorimeter radiators.
• Figure 3: Energy distributions for the PbWO$_4$ modules with the SiPM readout.
• Figure 4: JLab prototype with SiPM readout.
• Figure 5: CRYTUR prototype with SiPM readout.