Front-end ASIC for spectroscopic readout of virtual Frisch-grid CZT bar sensors

Abstract

Compact multi-channel radiation detectors rely on low noise front-end application specific integrated circuits (ASICs) to achieve high spectral resolution. Here, a new ASIC developed to readout virtual Frisch-grid cadmium zinc telluride (VFG CZT) detectors for gamma ray spectroscopy is presented.Corresponding to each ionizing event in the detector, the ASIC measures the amplitude and timing at the anode, the cathode and four pad sense electrodes associated with each sensor in a detector array. The ASIC is comprised of 52 channels of which there are 4 cathode channels and 48 channels which can be configured as either anode channels with a baseline of 250 mV or pad sense channels to process induced signals with a baseline of 1.2 V. With a static * Corresponding author power dissipation of 3 mW, each channel performs low-noise charge amplification, high-order shaping, peak and timing detection along with analog storage and multiplexing. The overall channel linearity was better than ± 1 % with timing resolution down to 700 ps for charges greater than 8 fC in the 3 MeV range. With a 4 x 4 array of 6 x 6 x 20 mm 3 virtual Frisch-grid bar sensors connected and biased, an electronic resolution of ≈ 270 a rms for charges up to 100 fC in the 3.2 MeV range was measured. Spectral measurements obtained with the 3D correction technique demonstrated resolutions of 1.8 % FWHM at 238 keV and 0.9 % FWHM at 662 keV.

AMEGO: Exploring the Extreme Multimessenger Universe

“…The module is read out by a single low-noise custom ASIC designed for the Frisch-grid detector 34 that is connected to the anode (bottom) side of the module. The top board of the module distributes an external 2500 V high-voltage source to bias the detectors.…”

Development of the ComPair gamma-ray telescope prototype

“…The crate is read out by a custom low-noise ASIC called the advanced virtual Frisch-Grid 2 (AVG2). 20 An Altera Arria GX FPGA then handles the data recording and ASIC controls. In ComPair, there are a total of 9 crates arranged in a 3 × 3 array, shown in Fig.…”

“…The CZT subsystem has undergone rigorous testing with its performance reported numerous times. 16,19,20 The CsI calorimeter's response to muons at around sea level using all channels. Note that (b) treats each interaction in the calorimeter as an independent event.…”

Subsystem Development for the All-Sky Medium Energy Gamma-ray Observatory (AMEGO) prototype

“…The bars are arranged in a 4 × 4 module and connected to a readout ASIC (the AVG2 [8]) and FPGA module which controls readout. An individual module is 2.5 cm × 2.5 cm, the ComPair…”