Evaluation of simulated HPGe detector efficiencies in OpenMC compared to MCNP

Standardization of 243Am.

A comprehensive GEANT4 simulation framework is developed to model the background of the TEXONO experiment, considering contributions from radioactive isotopes in both the detector components and the ambient environment. In this framework, the HPGe detector's front-end electronics (pre-amplifier) are modeled to contain trace amounts of naturally occurring radionuclides 238U, 232Th, and 235U from manufacturing materials. The results confirm that the decay chains of 238U and 232Th dominate the background in this region. The observed background contributions from both isotopes are at the 𝒪(1) counts kg-1 keV-1 day-1 for energies below 400 keV. Trace radioisotopic impurities were introduced into the anti-Compton veto (ACV) detectors to reflect realistic material compositions: 40K was incorporated in the NaI(Tl) crystal consistent with its natural isotopic abundance, and 137Cs was included in the CsI(Tl) detector, representing a common anthropogenic contaminant. The analysis identifies minor yet measurable background components originating from 40K in the NaI(Tl) ACV detector and 137Cs in the CsI(Tl) scintillator. The residual spectrum is dominated by 40K γ-rays, with smaller components from 137Cs, in agreement with simulation results. The background rate from 40K is uniform at ∼ 0.1 counts kg-1 keV-1 day-1, approximately 10 times higher than that from 137Cs below 400 keV. To incorporate environmental sources of radioactivity, simulations included isotopes 60Co, 54Mn, and 135Xe distributed within the air gap between the copper end-cap and the NaI(Tl) ACV detector, representing airborne and surface-induced contamination. Although these sources contribute to the overall background (10-2, 10-2, and 0.1 counts kg-1 keV-1 day-1 below 100 keV for 135Xe, 54Mn, and 60Co, respectively), their effects are well controlled and constitute only minor components of the total background. The comparison between simulated and measured spectra, while showing minor deviations at specific γ-lines, demonstrates the validity of the background model and the robustness of the simulation framework for guiding detector and shielding design.

Accurate characterization of the HPGe detector dead layer is crucial for reliable Monte Carlo simulations in gamma-ray spectrometry. This study investigates the impact of source geometry on the determination of the effective dead layer thickness. Experimental measurements and MCNP6 simulations were conducted using a p-type coaxial HPGe detector with three geometries: a cylindrical source (S1), a 3π source (S2), and a Marinelli beaker (S3). Results show that while the physical dead layer distribution is intrinsic to the crystal, the determined effective dead layer parameter is strongly dependent on the irradiation geometry. The on-axis source (S1) indicated a stable frontal dead layer of approximately 0.60 mm. Conversely, volumetric sources (S2 and S3) revealed a thicker lateral dead layer (∼1.10–1.21 mm) with a significant transition zone at low energies due to the geometric weighting of photon interactions. Crucially, the study demonstrates that applying a uniform dead layer thickness derived from point-source calibration (S1) to volumetric geometries (S3) results in a systematic overestimation of efficiency across the energy range. These findings highlight the inadequacy of uniform dead layer models for complex geometries and the necessity of multi-region characterization for high-accuracy environmental monitoring.

Precision measurement of photon emission probabilities in 177Lu.

Functionally graded AA2024/B4C metal matrix composites were fabricated via mechanical alloying and hot pressing to investigate structure–property–radiation shielding relationships. Single-layer, two-layer, and three-layer architectures with varying B4C contents were systematically produced. Microstructural homogeneity and phase constitution were examined using SEM/EDS and XRD, while thermal stability was evaluated by thermogravimetric analysis. Density and porosity measurements were conducted to assess the influence of reinforcement distribution and functional grading on densification behavior. Gamma radiation shielding performance was experimentally evaluated using a 152Eu source and an HPGe detector over a wide photon energy range. Key shielding parameters, including linear and mass attenuation coefficients, half-value layer, tenth-value layer, mean free path, and radiation protection efficiency, were determined. The results reveal that functional grading significantly enhances radiation attenuation compared to monolithic composites. The three-layer AA2024/B4C composite exhibited the highest attenuation coefficients and the lowest HVL, TVL, and MFP values at all investigated energies, achieving nearly 100% improvement in shielding efficiency relative to unreinforced AA2024. These findings demonstrate that controlled B4C distribution and layered composite architecture provide a synergistic improvement in thermal stability, physical integrity, and radiation shielding performance, positioning functionally graded AA2024/B4C composites as efficient lightweight materials for advanced radiation shielding applications. These results indicate that the developed functionally graded AA2024/B4C composites are promising candidates for advanced radiation shielding applications in nuclear facilities, aerospace structures, and medical radiation protection systems, where lightweight and high-performance materials are critically required.

Concentration of 40K, 226Ra, 228Ra and 228Th in the main brands of pet food sold in Brazil.

Multifunctional polymethyl methacrylate-Boron carbide/bismuth oxide composites for gamma, neutron, and charged particle shielding applications.

The EURAMET.RI(II)-S9 interlaboratory comparison of the radionuclide calibrators.

Gd2O3/HDPE nanocomposite materials were prepared using the sol-gel method. These composites were developed to investigate the gamma-ray and neutron shielding properties of HDPE reinforced with Gd2O3 nanoparticles at different concentrations (x = 4.0%, 12.0%, 20.0%, 30.0%, and 40%). The study also investigates the effects of argon ion irradiation on the gamma-ray and neutron shielding properties. The composite was irradiated with argon ion beam of energy 4 keV, to a fluence of 22 × 1016 ions/cm2. Different analytical techniques were applied to study the Gd2O3/HDPE nanocomposites. The mass attenuation coefficient (µm) was experimentally measured using the Eu-152 gamma point source. The HPGe detector was used for measurement of shielding parameters of unirradiated and irradiated composites. The (µm) was measured at different photon energies, and the outcomes have been contrasted with those obtained utilizing the NIST-XCOM software. There was an acceptable agreement between the theoretical and experimental results. For example, at 121 keV, the attenuation parameter increases from 0.1845 for pure HDPE to 0.5065 for the 30 wt% Gd2O3/HDPE composite, corresponding to an enhancement of approximately 175%. Also, total neutron macroscopic cross-sections were evaluated for both irradiated and unirradiated samples. Results revealed a significant enhancement in gamma and neutron attenuation post-irradiation, attributed to structural, mechanical, and morphological changes induced by the ion beam. For pure HDPE, ƩT increases by 33%, whereas the 12 wt% and 20 wt% Gd2O3/HDPE composites exhibit further enhancements of approximately 82% and 70%, respectively. The findings indicate ion treatment provides a promising method for improving radiation shielding parameters of polymer nanocomposites.

Characterization of carbon fiber window HPGe detector using Computed Tomography.

Effect of coaxial HPGe detector structure on <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si24.svg" display="inline" id="d1e653"> <mml:mi>γ</mml:mi> </mml:math> -ray beam measurements

Natural radioactivity present in coal mines has not only health hazards to miners but also to the population near to the coal mines. The coal mines of Dukki, Balochistan, are very close to the general population and have maximum coal seams in Balochistan. Therefore, coal waste of Dukki coal waste was investigated for radioactivity and associated health hazards from coal waste using HPGe and NaI detectors. The results obtained for 232Th and 226Ra through both detectors were found less than acceptable values, while in case 40K, the results obtained through both the detectors were found higher than permissible values. Positive correlations (R2 = 0.8428 for 226Ra), (R2 = 0.9866 for 232Th), and (R2 = 0.9857 for 40K) were obtained between the results obtained through both the detectors. Frequency distribution and box plots show normal distribution of radionuclides under investigations. The values obtained for all hazard indices through HPGe and NaI detectors were found less than world acceptable values. Therefore, it is concluded that the coal waste of Dukki coal mines may not pose any significant health hazards related to radioactivity.

In the present work an experimental measurement of the 203Tl(n,2n)202Tl reaction cross section is presented, at the incident energy En,lab = 14.6 MeV, using the activation technique, relative to the reference reaction 27Al(n,a)24Na. The experiment took place at the 5.5 MV TANDEM Van de Graaff accelerator of N.C.S.R. “Demokritos”, and the neutron beam was produced via the 3H(d,n)4He reaction. The foils were irradiated under an 80◦ angle. A BF3 detector was utilized to monitor the neutron flux during the irradiation. The irradiated foils were placed in front of HPGe detectors to measure the induced activity by gamma-ray spectroscopy. The neutron fluence was simulated using the MCNP software.

Determining the natural radium isotopes in waters by gamma-ray spectrometry with an HPGe detector

Calibration transfer from HPGe to NaI(Tl) detectors for radionuclides quantification.

Generation of Simulated signal database for segmented Planar HPGe Detector

Geant4 model to estimate the dead layer thickness of the HPGe detector

Accuracy of machine learning algorithms for HPGe detector efficiency determination

The cross section of the 82Kr(n, p)82Br reaction induced by d-T neutrons was measured using the activation method. Incident neutrons are generated through the 3H(d, n)4He reaction. High-purity natural krypton gas held at high pressure was used as the target sample. The neutron energy and its uncertainty were determined based on the Q-value equation of the 3H(d, n)4He reaction and the experimental conditions. The neutron fluence incident on the sample is monitored by the 27Al(n, α)24Na reaction. The eight characteristic gamma rays of the 82Br daughter nucleus were selected to determine its activity by off-line gamma spectrometry using an HPGe detector. The 82Kr(n, p)82Br reaction cross sections with lower uncertainties were finally determined at five neutron energies by the weighted method. The measured cross sections were compared with previous experimental studies, theoretical values from Talys-2.0, calculation results from the systematics (empirical and semi-empirical) formulas, and evaluation results. The present high-precision cross sections for the 82Kr(n, p)82Br reaction over a wide energy range not only help to validate and evaluate nuclear reaction models, but also substantially enrich the neutron-induced nuclear reaction cross sections database.