Conical liquid noble gas apparatus for neutrino physics.

Introduction

Coherent elastic neutrino-nucleus scattering (CENS) is a recently demonstrated novel process of neutrino interaction. It provides numerous avenues to advance our sensitivity to new physics beyond the Standard Model and enables a miniaturization of otherwise massive neutrino detectors, opening up the possibility of technological applications.

Project Proposal

The development of an innovative single-phase noble liquid time projection chamber (TPC) to detect CENS is proposed. Two distinct ideas are combined to maximize the potential of the technique:

1. The signal will be amplified through electroluminescence (EL).
2. The TPC will be shaped as a conical frustum.

Technical Details

Single-phase EL is unaffected by charge trapping, which is the major deterrent of dual-phase noble liquid TPCs for CENS searches at shallow depths. However, it requires extremely high electric fields. Such fields can be reached by using very thin wires of m-scale diameter. This is an impediment to producing large amplification regions.

Common TPC shapes are thus limited in size and target mass. The conical shape allows for maximizing the mass by drifting all charges towards a small amplification region at the smaller circle of the cone. This scheme allows for good coverage with few sensors.

Implementation

COLINA, a conical TPC capable of holding 50 kg of LXe, will be developed and deployed at the largest spallation neutrino source, the European Spallation Source. Simulations point to a conservative energy threshold as low as 0.525 keVnr.

The detector will allow for operation with different noble gases. The increase in density of liquid-phase, compared to gaseous-phase, results in a large CENS rate with rather small detectors. In fact, COLINA will produce the largest CENS statistics in all the considered isotopes, Xe, Kr, and Ar, and will do so in unexplored energy regions for the process, where the physics relevance is maximal.