A Low-Power, Portable Radiation Detection System for High Count Rate, Long-Term Monitoring

This article presents a standalone gamma radiation detection system designed to support high count rates while preserving spectral fidelity and low-power, long-term operation. The system incorporates a detector based on a scintillator and photomultiplier tube (PMT), a detector power supply (DPS), and a custom system-on-chip (SoC) implementing a multichannel analyzer (MCA) for processing the detector signal. The MCA contains two on-chip resources to prevent spectral degradation over high and varying count rates. The first, based on an array of current mirrors, subtracts an error-inducing, count rate-dependent current from the signal path in slower scintillators such as CsI. The second resource utilizes a baseline restoration circuit to do the same for fast scintillators such as LaBr. Meanwhile, the DPS establishes the necessary bias voltages for the PMT using a separate low-power regulator chip without corrupting the signal. Both chips were fabricated, tested, and integrated onto a portable, handheld device that consumes 11 mW while detecting gamma rays at 30 000 counts per second (cps). The device can operate for over eight days when powered by two CR2477 button cell batteries.