TPC-like readout for thermal neutron detection using a GEM-detector

TL;DR

This paper introduces a novel TPC-like readout scheme for GEM detectors that achieves sub-200 um spatial resolution in thermal neutron detection by tracking secondary ions produced in a Boron-10 converter.

Contribution

It presents a new TPC-based readout method for GEM detectors that significantly improves spatial resolution in thermal neutron detection.

Findings

Achieved 100 um spatial resolution at 4.7 Å neutrons.

Used a 2 um Boron-10 converter cathode for neutron capture.

Implemented a 2D readout with 400 um pitch using APV25 chips.

Abstract

Spatial resolution of less than 200 um is challenging for thermal neutron detection. A novel readout scheme based on the time-projection-chamber (TPC) concept is used in a gaseous electron multiplier (GEM) detector. Thermal neutrons are captured in a single 2 um thick Boron-10 converter cathode and secondary Helium and Lithium ions are produced with a combined energy of 2.8 MeV. These ions have sufficient energy to form straight tracks of several mm length. With a time resolving 2-dimensional readout of 400 um pitch in both directions, based on APV25 chips, the ions are tracked and their respective origin in the cathode converter foil is reconstructed. Using an Ar-CO2 93:7% gas mixture, a resolution of 100 um (FWHM 235 um) has been observed with a triple GEM-detector setup at the Garching neutron source (FRMII) for neutrons of 4.7 Angstrom.