A first principle method to simulate the spectral response of CdZnTe-based X- and gamma-ray detectors

Bettelli, Manuele; Amadé, Nicola Sarzi; Calestani, Davide; Garavelli, Bruno; Pozzi, P.; Macera, D.; Zanotti, L.; Gonano, Carlo Andrea; Veale, Matthew C.; Zappettini, A.

doi:10.1016/j.nima.2020.163663

Cited by 14 publications

(14 citation statements)

References 36 publications

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“…the output pulses from charge sensitive preamplifiers) are the result of photoelectric interactions of 662 keV photons from a 137 Cs source. The simulated pulses come from a custom procedure organized into three main blocks: (i) radiation-semiconductor interaction with Monte Carlo methods (Geant4) (Agostinelli et al, 2003), (ii) electric and weighting field calculation by the finite element method (FEM) with COMSOL Multiphysics and (iii) calculation of the charge carrier transport and pulse formation in a MATLAB environment (Bettelli et al, 2020). The charge carrier transport properties used in the simulation are typical of Redlen CZT materials for low-flux applications (LF-CZT materials): e of 1100 cm 2 V À1 s À1 and e of 11 ms for electrons and h of 88 cm 2 V À1 s À1 and h of 0.2 ms for holes (Thomas et al, 2017).…”

Section: Figurementioning

confidence: 99%

“…5 also shows the presence of three different cathode pulses that can be attributed to the effects of charge sharing among cathode strips. If a 137 Cs photon is fully absorbed near the cathode side of the CZT detector, the size (FWHM) of the electron cloud, after drifting through the entire thickness of the crystal, can be estimated to about 350 mm (range of the photoelectrons, diffusion and repulsion) (Bettelli et al, 2020;Kim et al, 2011Kim et al, , 2014Bolotnikov et al, 2007). In particular, the pulse from cathode 7 (brown pulse) is an example of mixed inducedcollected-charge pulses, owing to the effects of both charge sharing and weighting potential cross talk.…”

Section: Induced-charge Pulses With Positive-and Negativesaturation Lmentioning

confidence: 99%

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Recent advances in the development of high-resolution 3D cadmium–zinc–telluride drift strip detectors

et al. 2020

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In the last two decades, great efforts have been made in the development of 3D cadmium–zinc–telluride (CZT) detectors operating at room temperature for gamma-ray spectroscopic imaging. This work presents the spectroscopic performance of new high-resolution CZT drift strip detectors, recently developed at IMEM-CNR of Parma (Italy) in collaboration with due2lab (Italy). The detectors (19.4 mm × 19.4 mm × 6 mm) are organized into collecting anode strips (pitch of 1.6 mm) and drift strips (pitch of 0.4 mm) which are negatively biased to optimize electron charge collection. The cathode is divided into strips orthogonal to the anode strips with a pitch of 2 mm. Dedicated pulse processing analysis was performed on a wide range of collected and induced charge pulse shapes using custom 32-channel digital readout electronics. Excellent room-temperature energy resolution (1.3% FWHM at 662 keV) was achieved using the detectors without any spectral corrections. Further improvements (0.8% FWHM at 662 keV) were also obtained through a novel correction technique based on the analysis of collected-induced charge pulses from anode and drift strips. These activities are in the framework of two Italian research projects on the development of spectroscopic gamma-ray imagers (10–1000 keV) for astrophysical and medical applications.

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Section: Figurementioning

confidence: 99%

Section: Induced-charge Pulses With Positive-and Negativesaturation Lmentioning

confidence: 99%

Recent advances in the development of high-resolution 3D cadmium–zinc–telluride drift strip detectors

et al. 2020

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“…By increasing the energy, the extent of Compton scattering grows, hence the enhancement is more evident. First of all, it should be emphasized that these results prove and confirm the accuracy of the simulation tool used to produce the response function R [ 31 ]. Secondly, this approach effectively takes advantage of all the information contained in the measured spectra to reconstruct and enhance even the weakest photopeaks without prior assumptions about the incident radiation.…”

Section: Discussionmentioning

confidence: 59%

“…The response function

of both detectors was obtained using the simulation tool described in [ 31 ], which considers each step of the signal generation process, from the radiation–matter interaction to the charge transport to the signal induction on contacts. We tested the algorithm on four different radioactive sources:

and

with the drift strip detector;

and

with the single pixel detector.…”

Section: Methodsmentioning

confidence: 99%

Gamma-Ray Spectral Unfolding of CdZnTe-Based Detectors Using a Genetic Algorithm

Amadé

Bettelli

Zambelli³

et al. 2020

Sensors

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The analysis of γ-ray spectra can be an arduous task, especially in the case of room temperature semiconductor detectors, where several distortions and instrumental artifacts conceal the true spectral shape. We developed a genetic algorithm to perform the unfolding of γ-spectra in order to restore the true energy distribution of the incoming radiation. We successfully validated our approach on experimental spectra of four radionuclides (241Am, 57Co, 137Cs and 133Ba) acquired with two CdZnTe-based detectors with different contact geometries (single pixel and drift strip). The unfolded spectra consist of δ-like peaks in correspondence with the radiation emissions of each radioisotope.

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“…Figure 1 shows the simulated evolution of the electron charge cloud size (FWHM) in a CZT detector vs. the drift distance, which is generated by photoelectrons in the energy range of 25–662 keV. The simulation involves the physical processes of Coulomb repulsion and charge diffusion [ 26 ]. It consists of three main procedures: (i) the radiation–semiconductor interaction with Monte Carlo methods (Geant4), (ii) electric and weighting field calculation by the finite element method (FEM) with COMSOL Multiphysics, and (iii) the calculation of the charge carrier transport and pulse formation in a MATLAB environment.…”

Section: Charge-sharing Cross-talk Phenomena and Correction Techniquesmentioning

confidence: 99%

Energy Recovery of Multiple Charge Sharing Events in Room Temperature Semiconductor Pixel Detectors

Buttacavoli

Gerardi

Principato

et al. 2021

Sensors

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Multiple coincidence events from charge-sharing and fluorescent cross-talk are typical drawbacks in room-temperature semiconductor pixel detectors. The mitigation of these distortions in the measured energy spectra, using charge-sharing discrimination (CSD) and charge-sharing addition (CSA) techniques, is always a trade-off between counting efficiency and energy resolution. The energy recovery of multiple coincidence events is still challenging due to the presence of charge losses after CSA. In this work, we will present original techniques able to correct charge losses after CSA even when multiple pixels are involved. Sub-millimeter cadmium–zinc–telluride (CdZnTe or CZT) pixel detectors were investigated with both uncollimated radiation sources and collimated synchrotron X rays, at energies below and above the K-shell absorption energy of the CZT material. These activities are in the framework of an international collaboration on the development of energy-resolved photon counting (ERPC) systems for spectroscopic X-ray imaging up to 150 keV.

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A first principle method to simulate the spectral response of CdZnTe-based X- and gamma-ray detectors

Cited by 14 publications

References 36 publications

Recent advances in the development of high-resolution 3D cadmium–zinc–telluride drift strip detectors

Recent advances in the development of high-resolution 3D cadmium–zinc–telluride drift strip detectors

Gamma-Ray Spectral Unfolding of CdZnTe-Based Detectors Using a Genetic Algorithm

Energy Recovery of Multiple Charge Sharing Events in Room Temperature Semiconductor Pixel Detectors

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