Gamma Spectroscopy with SiPM & Redpitaya

Abstract: in this article, we present the design of a gamma spectrometer based on a Cesium Iodide (CsI(Tl)) scintillator coupled to a silicon photomultiplier (SiPM). The signal produced by the SiPM is pre-amplified and then sent to a shaping amplifier to form a low-noise Gaussian pulse. The signal is acquired by a Red Pitaya board and processed using the multichannel analyzer application. Gamma spectra are displayed using the dedicated Interspec application.

Introduction

The project proposed in this work consists of a gamma spectrometer based on a CsI(Tl) scintillator coupled to a solid-state photomultiplier (SiPM). The image below shows the setup, including the “dark box” that houses the detector and the preamplifier. The signals displayed on the oscilloscope are the pulse produced by the SiPM and the preamplified pulse.

Detail of the “dark box” with the detector and the amplifier.

Test source positioned above the detector.

Detail of the scintillator wrapped in opaque, reflective tape.

Detail of the “shaper amplifier”.

The amplified signal is then acquired by the Red Pitaya board and processed using the multichannel analyzer application (Alpha Spectroscopy with Red Pitaya). The result is shown in the following graph, displaying the gamma spectrum of the Cesium-133 source.

The acquired signal can be exported in a standard format and read by the Interspec program, which enables detailed analysis of the gamma spectrum.

Spectrum γ Cs-133

Spectrum γ Am-241

Spectrum γ Na-22

Spectrum γ Th-232

Conclusions

The gamma spectrometer described in this article has proven to be an efficient instrument suitable for measuring low-intensity sources with relatively good energy resolution.

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