Material For Radiation Detectors Research Articles

Microstructure evolution of CdZnTe crystals irradiated by heavy ions

Consideration of irradiation effects is important for in-orbit operation and radiation protection in aerospace applications. The configuration of irradiation defects and their impact on deteriorating the carrier transport properties of CZT crystals need to be clarified. In this study, the microdefect evolution mechanism of CdZnTe (CZT) crystals under 10 MeV Chlorine (Cl) ion irradiation at flux of 1×1010∼1×1012 n·cm-2 are investigated. The stacking faults first appear in the CZT crystal at 4.5×10-4 displacement per atom (dpa), which are categorized into slip-type, gap-type and vacancy-type. In order to hinder the further expansion of stacking fault, S-shaped stacking fault dipole appears. When the dpa reaches 4.5×10-2, the local phase transition occurs in the damage zone to form CuPt-A ordered phase with ZnTe/CdTe periodic arrangement because the fluctuation in local composition and strain caused by cascade collisions. The deterioration of electric field distribution and charge collection caused by irradiation damage layer leads to the decrease of γ-ray detection ability. The energy resolution (ER) of the CZT detector for γ-ray can be maintained at 30.6% when the ion flux accumulates to 1×1012 n·cm-2, revealing high irradiation hardness. Consequently, these findings provide a theoretical basis for the radiation damage recovery of CZT detectors, further demonstrating that CZT crystals are the most competitive new generation of room-temperature nuclear radiation detection materials, and can provide radiation protection strategies for similar compound semiconductor materials.

Controllable Multi-Exciton Zero-Dimensional Antimony-Based Metal Halides for White-light Emission and β-Ray Detection.

Self-trapped exciton (STE) emission, typified by antimony (Sb), with broadband characteristics, represents the next generation of materials for solid-state lighting and radiation detection. However, little is known about the multiexciton behavior of the Sb emission center. Here, we proposed a general approach for designing antimony-centered multi-exciton emitting materials through self-assembly. Benefitting from controllable multiexciton behavior, dual-band white light emission spanning the entire visible spectrum was achieved. Relying on the reduction of an effective atomic number brought by self-assembly, excellent scintillation response to β-rays was attained. This study offers unprecedented insight into hybrid single/triple STE emission and unveils new avenues for single-emitter white-light emission, as well as radiographic testing using low-risk β-rays as sources.

PEAI Surface Treatment for Low Ion Migration and High-Performance FAPbBr3 Single-Crystal X-ray Detectors.

Organometal halide perovskite single crystals (SCs) are the most promising candidates for the next generation of radiation detection materials. However, surface defects severely affect their detection performance and limit further applications. Here, we identified the surface defect types of FAPbBr3 SCs and employed phenethylammonium iodide (PEAI) solution to treat the crystal surface and to investigate their effects on ion migration, photoelectric performance, and X-ray detection performance. Our experimental results demonstrated that the surface defects, such as the metallic Pb and Br vacancies, can be effectively passivated by both the PEAI and the two-dimensional (2D) PEA2PbI4 layers. The PEAI layer can elongate the carrier lifetime, lower the trap density, and suppress ion migration in FAPbBr3 SCs. The 2D PEA2PbI4 layer can form a dense and full surface coverage, suppress ion migration, and lower the dark current of the SCs. The X-ray sensitivity of the PEAI-passivated FAPbBr3 SC detectors is 227.93 μCGyair-1 cm-2, which is an order of magnitude higher than that of the pristine FAPbBr3 SC detectors. This work demonstrates that surface treatment plays a critical role in the crystal quality and the X-ray detection performance of SCs.

X-ray-induced long persistent luminescence of Cu+-doped high alumina borosilicate glass

A Cu+ doped high alumina borosilicate glass with long persistent luminescence (LPL) was prepared by reduction melting and radiation induction based on glass defect engineering. The maximum time of the persistent luminescence can arrive 16 h. Spectral and EPR measurements indicate that two kinds of oxygen defects can be induced by X-ray radiation. One defect was eliminated after UV irradiation, and the other can synergistically participate in the LPL process of glass with reduction induced oxygen deficiency centers(ODCs). In addition, there is a highly linear relationship between the initial LPL intensity of the glass and the radiation dose; which implies the glass can be used as a radiation detection material. The internal mechanism of the linear relationship and LPL was discussed.

Exciton-harvesting enabled efficient charged particle detection in zero-dimensional halides

Materials for radiation detection are critically important and urgently demanded in diverse fields, starting from fundamental scientific research to medical diagnostics, homeland security, and environmental monitoring. Low-dimensional halides (LDHs) exhibiting efficient self-trapped exciton (STE) emission with high photoluminescence quantum yield (PLQY) have recently shown a great potential as scintillators. However, an overlooked issue of exciton-exciton interaction in LDHs under ionizing radiation hinders the broadening of its radiation detection applications. Here, we demonstrate an exceptional enhancement of exciton-harvesting efficiency in zero-dimensional (0D) Cs3Cu2I5:Tl halide single crystals by forming strongly localized Tl-bound excitons. Because of the suppression of non-radiative exciton-exciton interaction, an excellent α/β pulse-shape-discrimination (PSD) figure-of-merit (FoM) factor of 2.64, a superior rejection ratio of 10−9, and a high scintillation yield of 26 000 photons MeV−1 under 5.49 MeV α-ray are achieved in Cs3Cu2I5:Tl single crystals, outperforming the commercial ZnS:Ag/PVT composites for charged particle detection applications. Furthermore, a radiation detector prototype based on Cs3Cu2I5:Tl single crystal demonstrates the capability of identifying radioactive 220Rn gas for environmental radiation monitoring applications. We believe that the exciton-harvesting strategy proposed here can greatly boost the applications of LDHs materials.

Mapping and Characterization of Local Structures of CsPbBr3.

Inorganic perovskite CsPbBr3 is a promising material for optoelectronic applications and high-energy radiation detection due to its excellent photophysical properties, high carrier mobility, large carrier diffusion length, and higher stability than organic perovskite materials. Understanding phase transitions at the atomic level is crucial for optimizing its applications. Here, we employ experimental characterizations and molecular dynamics simulations to study the phase transitions in CsPbBr3 as a function of temperature. The simulation results are compared with the experimental results, which include X-ray diffraction (XRD). Our simulations provide new insights into the electronic structure and dynamic behavior of the Cs, Pb, and Br atoms as a function of temperature. We observe distinct phase transitions from monoclinic to cubic and analyze the associated changes in the local environment through atomic density contour maps. Our analysis of the atomic density distributions of the Pb, Br, and Cs atoms provides information about the crystal symmetry as a function of temperature. The tilt and rotation angles of [PbBr6] octahedra are increasing with the temperature increase and are found nonzero above 410 K when the structure is cubic, exhibiting the presence of dynamic tilting. Overall, our findings shed light on the thermal stability and structural dynamics of CsPbBr3, contribute to the fundamental understanding of its phase behavior, and provide a crucial pivot for guiding the design of next-generation optoelectronic and radiation detection devices.

A novel material for radiation detection application of zinc bismuth lithium borotellurite glass doped with Dy2O3

Radiation detection glass with the following chemical composition B2O3–TeO2–Li2O3–Bi2O3–ZnO doped with Dy2O3 where x = 0.00, 0.10, 0.50, 1.00, 1.50 and 2.00 mol%, was developed for the characterization of physical properties such as density, molar volume (Vm), and refractive index, optical absorption, luminescence, CIE's diagram, and radiation detection properties. The density and refractive index of glass samples increase with the increase of Dy2O3 composition. The optical property of glass shows eight strongest peaks from 6H15/2 centering at 263 nm (4I13/2 + 4F7/2), 298 nm (4G11/2), 357 nm (4I15/2), 803 nm (6F5/2), 897 nm (6F7/2), 1090 nm (6H7/2 + 6F9/2), 1272 nm (6F11/2 + 6H9/2) and 1671 nm (6H11/2), respectively. The emission peaks are r (4F9/2), 481 nm (6H15/2), 575 nm (6H13/2), 664 nm (6H11/2), and 751 nm (6H9/2) under excited at 453 nm (4F9/2), respectively. The excitation peaks under emission at 575 nm from 6H15/2 centering at 350 nm (6P7/2), 365 nm (4P3/2), 388 nm (4K17/2), 425 nm (4G11/2), 453 nm (4I15/2), and 471 nm (4F9/2) respectively. The study of luminescence characteristics, which includes emission, excitation, and CIE diagrams, reveals white emission bands that coincide with the CIE diagram. Furthermore, measuring the parameters of the thermoluminescence dosimeter (TLD) recorded with a heating rate of 5 °C/s in the temperature up to a maximum of 400 °C yields good results in low dose radiation detection. Based on all the results, it was determined that this glass can be a candidate for radiation detection materials in the future.

Preparation and Application of Nanostructured ZnO in Radiation Detection.

In order to adapt to the rapid development of high-speed imaging technology in recent years, it is very important to develop scintillators with an ultrafast time response. Because of its radiation-induced ultrafast decay time, ZnO has become an important material for radiation detection and dosimetry. According to different detection sources and application scenarios, ZnO is used in various radiation detectors in different structures, including nanoarrays and nanocomposites. In this paper, the synthesis methods and research status of various nanostructured ZnO-based materials and their applications in the detection of high-energy rays (X-rays, γ-rays) and high-energy particles (α, β and neutron) are reviewed. The performance discussion mainly includes spatial resolution, decay time and detection efficiency.

Effect of Dual-Organic Cations on the Structure and Properties of 2D Hybrid Perovskites as Scintillators.

Two-dimensional (2D) hybrid organic-inorganic perovskite (HOIP) crystals show promise as scintillating materials for wide-energy radiation detection, outperforming their three-dimensional counterparts. In this study, we synthesized single crystals of (PEA2-xBZAx)PbBr4 (x ranging from 0.1 to 2), utilizing phenethylammonium (C6H5CH2CH2NH3+) and benzylammonium (C6H5CH2NH3+) cations. These materials exhibit favorable optical and scintillation properties, rendering them suitable for high light yield (LY) and fast-response scintillators. Our investigation, employing various techniques such as X-ray diffraction (XRD), photoluminescence (PL), time-resolved (TR) PL, Raman spectroscopy, radioluminescence (RL), thermoluminescence (TL), and scintillation measurements, unveiled lattice strain induced by dual-organic cations in powder X-ray diffraction. Density functional theory analysis demonstrated a maximal 0.13 eV increase in the band gap with the addition of BZA cation addition. Notably, the largest Stokes shift of 0.06 eV was observed in (BZA)2PbBr4. The dual-organic cation crystals displayed >80% fast component scintillation decay time, which is advantageous for the scintillating process. Furthermore, we observed a dual-organic cations-induced enhancement of electron-hole transfer efficiency by up to 60%, with a contribution of >70% to the fast component of scintillation decay. The crystal with the lowest BZA concentration, (PEA1.9BZA0.1)PbBr4, demonstrated the highest LYs of 14.9 ± 1.5 ph/keV at room temperature. Despite a 55-70% decrease in LY for BZA concentrations >5%, simultaneous reductions in scintillation decay time (12-32%) may work for time-of-flight positron emission tomography and photon-counting computed tomography. Our work underscores the crucial role of dual-organic cations in advancing our understanding of 2D-HOIP crystals for materials science and radiation detection applications.

Cryogenic setup for the characterization of wavelength-shifting materials for noble element radiation detectors

In the present work, we describe a new cryogenic setup for studies of wavelength-shifting materials for optimised light collection in noble element radiation detectors, and discuss the commissioning results. This SiPM-based setup usesαinduced scintillation in gaseous argon as the vacuum ultraviolet light source with the goal of characterising materials, such as polyethylene naphthalate (PEN) and tetraphenyl butadiene (TPB), in terms of their wavelength-shifting efficiency. Preliminary results obtained with the system are consistent with the ones reported in literature: 0.5±0.05 in terms of WLS efficiency (PEN/TPB). A value of 1.24 μs was obtained for the triplet lifetime in Ar, which is a factor of 2.6 smaller than the one described in literature due to the presence of impurities. Further extensions of the system are currently being studied. The foreseen upgrades are expected to allow the study of GEM-like structures potentially interesting for rare-event searches. The design of the setup will be addressed along with the first results.

Investigation of gamma induced effects on the properties of gamma irradiated Ce2S3 thin films

Nanostructure cerium sulphide (Ce2S3) thin films were prepared using successive ionic layer adsorption and reaction (SILAR). The properties of the prepared samples were investigated as a function of gamma rays’ doses of 0, 250, 500, and 1000Gy, respectively. The X-ray diffraction (XRD) results suggest an orthorhombic phase structure for Ce2S3 thin films and the crystallinity is enhanced with increasing gamma-ray doses. The irradiated thin films exhibit a variation in the energy band gap associated with the quantum confinement effect with larger grain size. This simple strategy of modifying properties of Ce2S3 thin films by the incident gamma rays can be an attractive way to investigate this material for dosimetry and radiation detection.

Synthesis of Al quantum dots on porous silicon as an effective radiation detector using extended gate technique

In this study, porous silicon (PS) and aluminum (Al) doped porous silicon were synthesized through an electrochemical method, utilizing carefully selected parameters. The etching procedure was calibrated with a 4:1 HF/ethanol ratio, maintaining a current of 20 mA for 20 min, and incorporating 0.05 g of doping powder. Comprehensive structural analysis using FESEM-EDX revealed the incorporation of Al into the porous silicon matrix. Subsequently, the samples were covered with a finger mask, which facilitated the creation of an interdigitated electrode using a sputtering deposition method. The I–V characteristics of the samples were systematically studied, showing an increase in bias voltage at the source correlated with the measured current. Remarkably, upon X-ray exposure, pulses were successfully measured, highlighting the potential of these materials for radiation detection. These pulses were evaluated under various X-ray irradiation parameters using a sample detector. The study successfully identified the optimal parameters for PS and Al-PS as (90 V, 100 mA, 1 s) and (100 V, 10 mA, 0.5 s), respectively. This research underscores the potential applications of these materials in advanced electronic devices and sensors. The unique properties of synthesized porous silicon, particularly when doped with aluminum, could be beneficial in areas such as photovoltaics, biosensors, and photonics. Additionally, the material's efficiency in detecting X-ray radiation suggests its suitability for medical imaging, security scanning, and radiation monitoring systems. Based on the I–V characteristic studies, these materials may be well-suited for use in electronic components requiring precise control of electrical properties. Overall, this study not only enhances our understanding of porous silicon and aluminum-doped porous silicon but also opens up new avenues for their application in a wide range of sensing technologies.

A new Excel-based Monte Carlo transport code for simulating energy response spectra and efficiencies in gamma-ray detection materials

This study presents and assesses a new, user-friendly, and Excel-based Monte Carlo photon transport code, specifically designed to simulate Gaussian energy broadened response spectra of gamma-ray detector materials. This vectorized code utilizes the EPICS2017 photoatomic data library, with unionized energy grid construction, to facilitate precise and efficient photon transport simulations in any user-defined materials composition. Performance benchmarks were conducted using PHITS 3.31, with both basic and detailed models of a gamma-ray scintillator system, and detection crystals of NaI(Tl) and LaBr3(Ce). These benchmarks spanned a wide array of photon source monoenergetic emissions. Detector model efficiency was determined through automated peak area analysis, employing algorithms from the Ortec GammaVision software. The results indicated only minor spectral differences between the Excel-based code and the PHITS models, particularly within the range of practical gamma-ray energies and near-zero source-detector distances. Efficiency curves demonstrated good agreement between the Excel-based code and PHITS models, especially within the energy range of approximately 200 keV to a few MeV, with increasing agreement as detector crystal size increased. Comparisons were conducted with the existing data in literature at source-detector distances of 2 cm and 5 cm, using a detector crystal size of 2”. These comparisons support the code’s validity and its implementation of a basic geometry. This new Excel-based code appears as a promising tool with potential applications in radiation detector characterization and materials research.

Effects of UVC irradiation on polystyrene for healthcare packaging: Study by FTIR and Raman spectroscopy with thermoluminescence

The interaction between ultraviolet C radiation (UVC) and polystyrene (PS) materials has been investigated, particularly in post-packaging irradiation processes for healthcare applications. Effective UVC penetration through PS materials, regardless of their thickness (0.16 and 0.40 mm) has been observed. However, the penetration effectiveness could be affected by the thickness of the PS material. Achieving optimal post-packaging UVC treatment requires a thorough evaluation of chemical composition and material thickness, especially in pharmaceutical and medical packaging industries.Preliminary results reveal minimal degradation in UVC-irradiated PS packaging samples, as supported by FTIR and Raman spectroscopy characterization. Minor variations could be attributed to intrinsic PS materials properties and/or their respective background, rather than the influence of UVC radiation. Consequently, PS materials exhibit resilience under the experimental conditions following UVC irradiation treatment. Furthermore, a comprehensive analysis of thermoluminescence (TL) emissions evaluates several commercial dosimeter materials for UVC radiation detection. The TLD-100 and TLD-200 dosimeters show potential as UVC detectors, displaying distinct responses linked to the non-ionizing component of UVC radiation at 310 °C and in the range of 150–250 °C, respectively. However, the TLD-400 and GR-200 dosimeters are not suitable for UVC detection due to their spread TL emissions considering intensity and curve shape.This UVC-TL analysis consistently detects radiation in the proposed commercial dosimeter materials one-hour post-exposure, providing assurance that healthcare materials have been irradiated. Such analysis enhances reliability during extended UVC exposures, offering valuable insights for industries employing UVC-irradiated materials, particularly in healthcare applications.

Efficient Direct X-ray Detection and Imaging Based on a Lead-Free Electron Donor-Acceptor MOF.

Metal-organic frameworks (MOFs) have recently gained extensive attention as potential materials for direct radiation detection due to their strong radiation absorption, long-range order, and chemical tunability. However, it remains challenging to develop a practical MOF-based X-ray direct detector that possesses high X-ray detection efficiency, radiation stability, and environmental friendliness. The integration of donor-acceptor (D-A) pairs into crystalline MOFs is a powerful strategy for the precise fabrication of multifunctional materials with unique optoelectronic properties. Herein, a new lead-free MOF, Cu2I2(TPPA) (CuI-TPPA, TPPA = tris[4-(pyridine-4-yl)phenyl]amine), with a 6-fold interpenetrated structure is designed and synthesized based on the electron donor-acceptor strategy. CuI-TPPA has a large mobility-lifetime (μτ) product of 5.8 × 10-4 cm2 V-1 and a high detection sensitivity of 73.1 μC Gyair-1 cm-2, surpassing that of commercial α-Se detectors. Moreover, the detector remains fairly stable with only a 2% reduction in photocurrent under continuous bias irradiation conditions with a total dose of over 42.83 Gyair. The CuI-TPPA/poly(vinylidene fluoride) flexible composite X-ray detector films are successfully manufactured with different thicknesses. Through multifaceted assessments, the optimal thickness is found with a high detection sensitivity of up to 143.6 μC Gyair-1 cm-2. As proof-of-concept, 11 × 9 pixelated X-ray detectors are fabricated on the same composite film to realize X-ray direct imaging. This work opens up potential applications of MOFs in environmentally friendly and wearable devices for direct X-ray detection and imaging.

Study of electric-field induced ionic migration on all-inorganic perovskite CsPbBr3 single crystal nuclear radiation detector

As one of the promising room temperature nuclear radiation detection materials, the all-inorganic perovskite CsPbBr3 single crystal has been receiving much attention in recent years. Even though the performance of the CsPbBr3 detector is improving continuously, the disadvantages of detection instability have not been solved fundamentally, and this instability is mainly caused by ionic migration in the CsPbBr3 single crystal itself. In this paper, a reasonable ionic migration model is proposed based on an in-depth study of the current hysteresis phenomenon and ionic migration mechanism in the Ti/CsPbBr3/Ti detector. The model shows that the ions migrate to the anode or cathode under an external electric field, and the accumulated ions subsequently form an inverted internal electric field inside the crystal and carrier transport barriers at the metal–semiconductor interface simultaneously. The photoelectric characteristic and ionic migration activation energy (Eaion) fitting results also prove the rationality of the ionic migration model. Furthermore, the ionic migration model can also be used to explain the left-shift of the energy response peak and the decrease in the normalized charge collection efficiency in the Ti/CsPbBr3/Ti detector. This paper systematically investigates the intrinsic origin of migrated ions and the influence of ionic migration on detection stability, which will provide a potential solution to improve detection stability by suppressing ionic migration in the near future.

Metal halide perovskite polymer composites for indirect X-ray detection.

Metal halide perovskites (MHPs) have emerged as a promising class of materials for radiation detection due to their high atomic numbers and thus high radiation absorption, tunable and efficient luminescent properties and simple solution processability. Traditional MHP scintillators, however, suffer from environmental degradation, spurring interest in perovskite-polymer composites. This paper reviews recent developments in these composites tailored for scintillator applications. It discusses various synthesis methods, including solution-based and mechanochemical techniques, that enable the formation of composites with enhanced performance metrics such as light yield, detection limit, and environmental stability. The review also covers the remaining challenges and opportunities in fabrication techniques and performance metric evaluations of this class of materials. By offering a comprehensive overview of current research and future perspectives, this paper underscores the potential of perovskite-polymer composites to revolutionize the field of radiation detection.

Electro-optical and thermoelectric properties of perovskite [formula omitted]: A DFT study

This study has reported electro-optical and thermoelectric properties of double-double perovskite CsKAgBiX6 compound in the cubic structure using density functional theory (DFT) computed using Quantum ESPRESSO software. The structural optimization was performed by the Birch-Murnaghan equation of state and the electronic properties indicate that the compounds are semiconductors with an indirect band gap of 1.5 eV, 2.1 eV and 2.6 eV for CsKAgBiI6, CsKAgBiBr6 and CsKAgBiCl6 respectively. The optical properties of these compounds are in the range of 0–15 eV, with high absorption coefficient increasing to the ultraviolet region. The thermoelectric properties are evaluated as a function of chemical potential at different temperatures, and the figure of merit obtained is 1.00 for CsKAgBiBr6 and CsKAgBiCl6 while that of CsKAgBiCl6 is 0.96 at room temperature. These results show that the compounds are reliable materials and candidate for Photovoltaics, radiation detector materials, as well as for thermoelectric applications.

Defects of perovskite semiconductor CsPbBr3 investigated via photoluminescence and thermally stimulated current spectroscopies

Halide perovskites are essential materials for hard radiation detectors at ambient temperature. To improve detector performance, charge transport must be investigated and optimized. Using photoluminescence (PL) and thermally stimulated current (TSC) spectroscopies, we investigate photogenerated charge carriers in Bridgman-grown CsPbBr3 single crystals to understand the nature of charge transport. PL spectroscopy of these halide perovskites revealed the presence of strong emission bands at the band edge, which were attributed to free or bound excitons. It is shown that a wide broadening of the excitonic linewidth in these halide perovskites arises from strong exciton–phonon coupling, which is substantially dominated by longitudinal optical phonons via Fröhlich interaction. An additional contribution due to the presence of ionized impurities was also observed. Crystals with a detectable sensitivity to high-energy gamma radiation are characterized by a higher intensity and a narrower linewidth of the principal PL peak at 2.326 eV. Defect states beyond 2.214 eV have a negative impact on detector sensitivity to high-energy gamma radiation. TSC spectroscopy reveals an array of trap levels spanning 0.15–0.70 eV, attributed to intrinsic point defects and multiple extrinsic defects involving dopants or impurities. Defects identified included Cs and Br vacancies, as well as Pb interstitials with concentrations in the 1011–1016 cm−3 range. Understanding how the synthesis process impacts the types and concentrations of the defects present is currently under investigation. Elimination or suppression of the defect/trap states should result in halide perovskite materials with longer carrier diffusion lengths and improved detector characteristics.

Radiation resistant optical components for high energy physics detectors

New detectors for future high-energy physics experiments will operate under unprecedented radiation dose rates. This condition requires improved radiation resistance on detector equipment. The consequent development of new materials, particularly optical materials, becomes crucial. In this work, optical components mean reflectors, light absorbers, or light transmitters. These materials, reflectors or light transmitters, are needed in detectors primarily to collect and transmit light from the scintillator to the PMT. When it comes to light absorbers, they are required to protect the detector from light from the environment. This work aims at studying selected optical materials with improved properties (functional and optical) and radiation resistance that can be used in new detectors at the Large Hadron Collider (LHC) experiments. Light transmittance, optical reflection, thermal characteristics, and radiation resistance were investigated to evaluate the proposed materials.We have developed optical systems based on siloxanes to continue our previous developments of radiation-resistant materials for radiation detectors. We also report a study of several reflective materials and light absorber introduced into the siloxane. Investigations have shown that these systems are radiation resistant to doses of at least 1 MGy.Tested samples were irradiated at linear electron accelerator LUE-40 in the National Science Center Kharkiv Institute of Physics and Technology (KIPT). The accelerated electrons were sent to the heavy complex targets to deliver the irradiation with gamma or neutron fluxes. The consequent gamma and neutron fluxes and doses were estimated with the GEANT4 simulation.