HEMT-based 1K front-end electronics for the heat and ionization Ge CryoCube of the future RICOCHET CE$\nu$NS experiment

TL;DR

This paper discusses the development of ultra-low noise HEMT-based front-end electronics for a 1K cryogenic Ge detector array in the RICOCHET CEνNS experiment, aiming for precise low-energy measurements.

Contribution

It introduces a novel HEMT-based front-end electronics design optimized for ultra-low noise performance at 1K for the RICOCHET experiment's Ge detector array.

Findings

Achieved predicted baseline resolutions of 10 eV heat and 20 eVee RMS.

Demonstrated high dynamic range up to 10 MeV for energy detection.

Optimized HEMT design with low dissipation of 15 μW per channel.

Abstract

The RICOCHET reactor neutrino observatory is planned to be installed at the Laue Langevin Institute (ILL) starting mid-2022. Its scientific goal is to perform a low-energy and high precision measurement of the coherent elastic neutrino-nucleus scattering (CE$\nu$NS) spectrum in order to explore exotic physics scenarios. RICOCHET will host two cryogenic detector arrays: the CryoCube (Ge target) and the Q-ARRAY (Zn target), operated at 10 mK. The 1 kg Ge CryoCube will consist of 27 Ge crystals instrumented with NTD-Ge thermal sensors and charge collection electrodes for a simultaneous heat and ionization readout to reject the electromagnetic backgrounds (gamma, beta, x-rays). We present the status of its front-end electronics. The first stage of amplification is made of High Electron Mobility Transistor (HEMT) developed by CNRS/C2N laboratory, optimized to achieve ultra-low noise performance at 1K with a dissipation as low as 15 $\mu$W per channel. Our noise model predicts that 10 eV heat and 20 eVee RMS baseline resolutions are feasible with a high dynamic range for the deposited energy (up to 10 MeV) thanks to loop amplification schemes. Such resolutions are mandatory to have a high discrimination power between nuclear and electron recoils at the lowest energies.