Electronics for the STEREO experiment

Victor Hélaine

doi:10.1088/1742-6596/888/1/012095

Abstract

The STEREO experiment, aiming to probe short baseline neutrino oscillations by precisely measuring reactor anti-neutrino spectrum, is currently under installation. It is located at short distance from the compact research reactor core of the Institut Laue-Langevin, Grenoble, France. Dedicated electronics, hosted in a single µTCA crate, were designed for this experiment. In this article, the electronics requirements, architecture and the performances achieved are described. It is shown how intrinsic Pulse Shape Discrimination properties of the liquid scintillator are preserved and how custom adaptable logic is used to improve the muon veto efficiency.

Highlights

The goal of the STEREO experiment is to probe the existence of light sterile neutrinos by precisely measuring the electron anti-neutrino energy spectrum at short distance (10 m) from the compact reactor core of the Institut Laue-Langevin (ILL)
Correlated background is produced by either spallation neutrons from muons or by fast neutrons from the reactor or neighbouring beam lines, with a prompt signal from neutron thermalisation and a delayed capture signal
Electronics concept The STEREO electronics are hosted in a μTCA crate, for compactness, modularity and versatility. It performs triggering in two stages with various selectable conditions, processing, readout and on-line calibration of the 68 photomultipliers (PMTs) – 48 for the detector and 20 for the veto – whose 100 to 200 ns signals are continuously digitised at 250 MSamples/s

Summary

Introduction

The goal of the STEREO experiment is to probe the existence of light sterile neutrinos by precisely measuring the electron anti-neutrino (νe) energy spectrum at short distance (10 m) from the compact reactor core of the Institut Laue-Langevin (ILL) (see [1, 2]). Electronics concept The STEREO electronics (see [5] for a full description) are hosted in a μTCA crate, for compactness, modularity and versatility (see Fig 1) It performs triggering in two stages with various selectable conditions, processing, readout and on-line calibration of the 68 photomultipliers (PMTs) – 48 for the detector and 20 for the veto – whose 100 to 200 ns signals are continuously digitised at 250 MSamples/s. For detector performance monitoring, on-line calibration by LED synchronised with the data acquisition is allowed These electronics have been designed to handle at least 1 kHz mean trigger rate. The ADC non-linearity has been measured using LEDs to be less than 1 % up to 1500 photo-electrons (PE), corresponding to 8 MeV νe Both single PE calibration and physics run can be performed thanks to FE8 pre-amplifiers two selectable gains (respectively ×20 and ×1).

PSD projection

Findings

Conclusion