A Tetramethylsilane TPC with Cherenkov light readout and 3D reconstruction

TL;DR

This paper presents the development and calibration of a liquid TPC using Tetramethylsilane with Cherenkov light readout, demonstrating its potential for rare event detection and radiation measurement.

Contribution

It introduces a novel TMS-based liquid TPC with combined charge and Cherenkov light readout, including calibration methods and performance metrics.

Findings

Measured most-probable energy loss for MIPs: 0.60±0.01 MeV/cm

Achieved electron lifetime of approximately 43 μs

Demonstrated prompt Cherenkov detection for fast signals

Abstract

We describe the construction and calibration of a multi-channel liquid time projection chamber filled with Tetramethylsilane (TMS). Its charge readout system consists of 8 wires each in the $X$ and $Y$ directions. The chamber is also equipped with a Cherenkov light readout system consisting of a 5-inch photomultiplier tube (PMT) coupled to the liquid volume through a viewport. The energy scale of the detector is calibrated using positron-electron pairs produced by 4.4 MeV gamma rays emitted from an AmBe source, using an external trigger on the positron annihilation gammas. The external trigger is then reconfigured to tag cosmic ray muons passing through the active TMS volume, which are used to measure the stopping power in TMS and the electron lifetime in the detector. We find a most-probable energy loss from minimum ionising particles (MIPs) of $\Delta_p/ds$ = (0.60$\pm$0.01) MeV/cm. We also derive an electron lifetime of 43$^{+680}_{-21}~\mu$s by measuring the most-probable energy loss as a function of drift time. For both fast electron and muon signals, the PMT detects prompt Cherenkov light, demonstrating the possibility of random triggering. The room-temperature organic target medium, together with the self-triggering capabilities and long electron lifetimes reported in this work, make this an attractive technology to further explore for rare event detectors or other applications in the area of radiation measurements.