The electronics of the energy plane of the NEXT-White detector

TL;DR

This paper details the design and implementation of low-radioactivity, high-precision electronics for the PMT energy plane of the NEXT-White detector, achieving high energy resolution and stable baseline handling.

Contribution

It introduces a novel digital baseline restoration method for AC-coupled PMT readout in a low-background detector environment.

Findings

Achieved energy resolution below 1%.

Demonstrated linearity better than 0.4%.

Noise levels below 0.4 mV.

Abstract

This paper describes the electronics of NEXT-White (NEW) detector PMT plane, a high pressure xenon TPC with electroluminescent amplification (HPXe-EL) currently operating at the Laboratorio Subterra\'aneo de Canfranc (LSC) in Huesca, Spain. In NEXT-White the energy of the event is measured by a plane of photomultipliers (PMTs) located behind a transparent cathode. The PMTs are Hamamatsu R11410-10 chosen due to their low radioactivity. The electronics have been designed and implemented to fulfill strict requirements: an overall energy resolution below 1% and a radiopurity budget of 20 mBq unit-1 in the chain of 214Bi . All the components and materials have been carefully screened to assure a low radioactivity level and at the same time meet the required front-end electronics specifications. In order to reduce low frequency noise effects and enhance detector safety a grounded cathode connection has been used for the PMTs. This implies an AC-coupled readout and baseline variations in the PMT signals. A detailed description of the electronics and a novel approach based on a digital baseline restoration to obtain a linear response and handle AC coupling effects is presented. The final PMT channel design has been characterized with linearity better than 0.4% and noise below 0.4mV .