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The anti-Compton phoswich (ACP) detector, which is composed of multiple scintillators with one photomultiplier tube, takes into account the Compton suppression function and portability, and therefore, a discussion on how to design its shape to improve the performance of the detector has become necessary. Based on an ACP detector using a well-typed LaBr3:Ce/NaI:Tl composite scintillator that has been developed in the laboratory in early work, this study uses GEANT4 to simulate and study the influence of the change in the shape and size of the secondary scintillator on the performance of the detector, such as the Compton suppression ratio, the energy resolution, and the full-energy peak (FEP) loss. In the course of the study, we mainly investigate the variation of the performance of the detector in two ways. First, the inclination angle of the truncated cone is gradually changed to compare its FEP address and Compton suppression ratio. Second, the case of the well-shaped and annular-shaped secondary scintillators is compared, respectively, to find out their impact on energy resolution and FEP address. The final results show that, compared with the ACP detector using a φ75 × 90 mm2 LaBr3:Ce/NaI:Tl cylindrical composite scintillator, a truncated cone-shaped composite scintillator of 0.8 inclination may have an equivalent 137% light yield (137% signal-to-noise ratio), a Compton suppression ratio of 89.62% (at 662 keV), 89.98% FWHM energy resolution, and a volume reduction of 36.74%, which means that the weight of the detector is reduced by 2.107 kg. [ABSTRACT FROM AUTHOR]

Obtaining directional information is required in many applications such as nuclear homeland security, contamination mapping after a nuclear incident and radiological events, or during the decontamination work. However, many directional radiation detectors are based on directional shielding, made of lead or tungsten collimators, introducing two main drawbacks. The first is the size and weight, making those detectors too heavy and irrelevant for utilization in handheld devices, drone mapping, or space applications. The second drawback is the limited field of view (FOV), which requires multiple detectors to cover the whole required FOV or machinery to rotate the detector’s narrow FOV detector. We propose a novel $4\pi $ directional detector based on a segmented hollow cubic detector, which uses the Compton effect interactions with no heavy collimators. The symmetrical cubical design provides both higher efficiency and $4\pi $ detection ability. Instead of the traditional two types of detectors (scatterer and absorber) structure, we use the same type of detector, based on Gd3Al2Ga3O12 (GAGG) (Ce) scintillator coupled to silicon photomultiplier. An additional advantage of the proposed detector is obtained by locating the photon sensors inside the detector, behind the scintillators, which improves the radiation hardness required for space applications. Furthermore, such an arrangement flattens the temperature variation across the detector, providing better gain stability. The main advantage of the proposed detector is an efficient $4\pi $ radiation detection for high-energy gamma rays without the use of heavy collimators. [ABSTRACT FROM AUTHOR]

An entrance window surrounded phoswich design of GAGG:Ce/CsI:Tl has been implemented for a low-background and Compton-suppressed detector. Not as the common phoswich detector does, the GAGG:Ce scintillator with the well-type CsI:Tl scintillator entrance window surrounded makes the efficient large-angle Compton suppression. This design also makes results measured by the phoswich detector have no degradation compared with the single GAGG:Ce detector. The Compton continuum and other backgrounds are reduced by identifying the gamma-ray energy depositions in different scintillators using the real-time rise time discrimination (RTD) method. The background rate is suppressed approximately 74%. The peak-to-total (P/T) ratio at 137Cs and 60Co point sources are 0.769 and 0.561, respectively. The Compton suppression is highly efficient at all the energy range of Compton continuums. The reduction of the Compton continuum and other backgrounds and the improvement of the P/T ratio will greatly expand the application range of the GAGG:Ce detector in low-intensity measurements. [ABSTRACT FROM AUTHOR]

A highly segmented muon spin rotation/relaxation/resonance (μ SR) spectrometer with over 2500 channels has been proposed in the construction of Phase II of the China Spallation Neutron Source (CSNS). Plastic scintillators are chosen as the detector material due to their high sensitivity to charged particles and good flexibility to various geometries. Gamma-ray sources are commonly used to calibrate the light yield of plastic scintillators. Accordingly, a derivative method has been developed to efficiently locate the Compton edge in gamma-ray spectra. In this method, the minimum and width of the derivative data are regarded as the position of the Compton edge and an estimation of energy resolution, respectively. Both experiments and simulations demonstrate the good reliability of this method for Compton edge positioning and energy resolution characterization. The derived Compton edge shows a systematic shift to the right of its real location. The relative shift is proportional to the energy resolution with a factor of ∼ 0.13. The assumed energy resolution should be corrected by a factor of ∼ 1.19 which is confirmed by inorganic scintillator measurements. In the measurement of plastic scintillators, the assumed Compton edge and energy resolution can well reproduce the energy response spectra for different types of gamma-ray sources. [ABSTRACT FROM AUTHOR]

As one of the detectors with superior performances, the Compton continuum in the spectra of the Cerium-doped Lanthanum 3-Bromide (LaBr 3 :Ce) detector should be suppressed for better performances. A compacted LaBr 3 :Ce/NaI:Tl phoswich detector has been designed to reduce the Compton continuum and improve the peak-to-total (P/T) ratio of the photopeaks. The LaBr 3 :Ce scintillator is surrounded by a well-type NaI:Tl scintillator and is coupled to a single photomultiplier tube (PMT). The Compton continuum is reduced by identifying the gamma-ray energy depositions in different scintillators using the real-time rise time discrimination (RTD) method. A Geant4 code with actual geometry was performed to simulate the suppressed and unsuppressed spectra. The peak efficiency of total energy at 1332 keV and 662 keV is 1.58% and 2.75%, the peak to total ratio at 137Cs point source and 60Co point source are 0.545 and 0.367, respectively. The reduction of the Compton continuum and the improvement of the P/T ratio will greatly expand the application range of the LaBr 3 : Ce detector in low-intensity measurements. [ABSTRACT FROM AUTHOR]

In the study of this paper, based on the symmetry of regular icosahedron, a spherical detector system for 4 π field-of-view (FOV) gamma imaging was proposed based on 80 GAGG (Ce:GAGG, Gd3Al2Ga3O12) scintillator pixels. The spherical detector system combines both coded aperture (CA) and Compton imaging (CI) modalities. The detector system was simulated precisely with an experimental test of one representative GAGG pixel. Several radionuclides with characteristic energy ranging from 59.5 keV to 1.33 MeV were imaged under the far-field situation. Both imaging modes realize the 4 π view while the coded aperture method achieves a higher image quality for radioactive sources with lower energy and the Compton method performs conversely. The imaging system can localize a 10 mCi 137Cs point source at 10 m within 1 s in the two modes and the Compton imaging mode reaches a high detection efficiency of up to 200 cps/ μ Sv/h for 137Cs. And the angular estimation full-width-at-half-maximum (FWHM) was approximately 5.2°for coded aperture mode and 14°for Compton mode. The angular resolution was evaluated to be better than 30°. The high intrinsic imaging sensitivity and reasonable imaging quality make this detector system design attractive for far-field radiation imaging. [ABSTRACT FROM AUTHOR]

Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) is mainly designed to detect Gamma-Ray Bursts associated with gravitational wave events. The lanthanum bromide (LaBr 3) scintillator with two types of doping (5% Ce 3 + only, 5% Ce 3 + co-doped with 1.5% Sr 2 +) are used in the Gamma-Ray Detectors (GRDs) of GECAM. Here, by analyzing the on-ground calibration data, we find different characteristics of these two doping types of LaBr 3 scintillator, including the Energy-Channel (E-C) relation, photon non-proportional response, energy resolution, as well as the electron non-proportional response which is derived from photon response and Monte Carlo simulation with Bayesian inference method. The results also show that the photon scintillation light yield and energy resolution can be improved by co-doping Sr 2 + in LaBr 3 :Ce 3 + scintillator, owing to a direct inhibitory effect on the electron non-proportional response. By taking the electron non-proportional response into account, we find that the simulated spectrum is in good agreement with the measured one, including Compton structure, escape peak of Lanthanum and Bromine as well as full energy peak, indicating that the electron non-proportional response is an essential factor in the energy response of scintillator detector thus should be considered in the data analysis. [ABSTRACT FROM AUTHOR]