Using the SIPHRA ASIC with an SiPM array and scintillators for gamma spectroscopy

SIPHRA is a low-power (30 mW) application specific integrated circuit (ASIC) recently developed by IDEAS, Norway for readout of photomultiplier tubes (PMTs) and silicon photomultipliers (SiPMs). The ASIC has 16 input channels and one summing channel. Each channel can be used for timing and pulse height spectroscopy with a programmable shaping time of 200 ns, 400 ns, 800 ns, or 1600 ns. The current mode input stage (CMIS) is designed for large negative charge (-6 nC, -8 nC, -4 nC, and -0.4 nC), depending on the programmable attenuation. The ASIC contains a 12-bit ADC for pulse-height digitization. SIPHRA's performance has been tested using a 4 × 4 array of 6 mm Jseries SiPMs from SensL and a number of scintillator crystals (BGO, LYSO, LaBr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> :Ce and CeBr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> ). The LaBr3:Ce detector has shown energy resolution (FWHM) of 3.4% at 662 keV and 2.5% at 1274 keV. In further measurements with a light emitting diode, the SiPMs have demonstrated the same energy resolution as obtained using discrete readout electronics.