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Coded-aperture gamma-ray imaging has great application value in the fields of nuclear security, nuclear facility decommissioning, and decontamination verification. However, conventional reconstruction methods cannot handle the signal-independent noise. In this paper, a coded-aperture imaging reconstruction method based on convolutional neural network (CNN) was proposed to improve the performance of image reconstruction and enhance the source position recognition ability of imaging systems. In addition, a compact gamma camera based on cadmium zinc telluride (CZT) pixel detector and uniformly redundant array (MURA) mask was modeled. Monte Carlo simulation data were used to train CNN and test the performance of this method. Furthermore, the reconstruction of the CNN method and the correlation analysis method with different radioactive sources and measurement conditions were compared. Results show that the proposed method can suppress the reconstructed image noise well. The reconstructed images have higher contrast-to-noise ratio (CNR) than the correlation analysis method in radioactive source location.

A spectrometer employing a silicon photomultiplier (SiPM) based scintillation detector has spectrum drift issues under temperature variations. Although some temperature-dependent compensation methods are reported, spectrum distortions under rapid temperature fluctuations have received little attention. We have developed a SiPM-based CsI(Tl) spectrometer and proposed gain stabilization designs to settle this problem. A temperature sensor was coupled to the SiPM in the detector and wrapped with a thermal insulation foam material to acquire the temperature of the SiPM. Meanwhile, a temperature correction module was applied in the field-programmable gate array (FPGA) within a custom multichannel analyzer (MCA). The effectiveness of the temperature correction module in the FPGA and a specialized detector design were studied and verified under slow and rapid temperature variations. The results prove that the spectrum drifts of the SiPM-based CsI(Tl) spectrometer under rapid temperature variations can be significantly constrained with the proposed gain stabilization designs.

The shift of baseline has always existed in high-pressure xenon (HPXe) detectors because of the influence of external acoustic noise. This problem seriously influences the spectrometric characteristics of these detectors. A special baseline restoration method is required to remove the shift of baseline in real time. This study demonstrated that the top hat transform based on mathematical morphology can restrain the shift of baseline in digital multichannel analyzer. An improved baseline restoration (IBLR) method based on mathematical morphology was proposed and implemented in field programmable gate array (FPGA) to obtain superior baseline restoration. The structuring element of the IBLR method can be adjusted automatically in real time according to the characteristics of the baseline. Experimental results show that the IBLR method can maintain an excellent energy resolution over a wide shift range of baseline. To strengthen our conclusion, we carried out an external acoustic noise experiment on a HPXe detector. The HPXe detector with IBLR was virtually unaffected by external acoustic noise.

X-ray communication (XCOM) is a new communication type and is expected to realize high-speed data transmission in some special communication scenarios, such as deep space communication and blackout communication. This study proposes a high-speed modulated X-ray source scheme based on the laser-to-X-ray conversion. The temporal characteristics of the essential components of the proposed laser-modulated pulsed X-ray source (LMPXS) were analyzed to evaluate its pulse emission performance. Results show that the LMPXS can provide a maximum modulation rate up to 100 Mbps which is expected to significantly improve the data rate of XCOM.

A collimating/focusing (C/F) optical system could greatly reduce the power requirements and improve the communication performance in space communication. Based on the known X-ray source, this paper proposed a hard X-ray multilayer collimating/focusing optical system for X-ray communication (XCOM) in 10–30 keV region. The C/F optical system helps effectively realize XCOM with high gain and high signal to noise ratio (SNR) hundreds of kilometers away. This paper discusses the reflectivity of multilayers, the optimization of supermirrors, the design of C/F optical system for hard X-ray, and the ray tracing process. Results shows that the collection efficiency of hard X-ray is greatly improved, and still remains 0.0196% 1000 km away from the X-ray source. When the transmitting power of X-ray is 100 W, the SNR reaches 71.8 dB at 100 km and 50.1 dB at 1000 km, respectively. This work provides some theoretical and actual values for improving the practical application of X-ray communication in entry blackout and space exploration.

In view of the demand for high-energy and high-bandwidth signal detection in X-ray communication (XCOM) during spacecraft reentry blackout, a detection module using fast-decay LYSO scintillator coupled with Silicon photomultiplier (SiPM) was proposed in this study. The theoretical model based on the Monte Carlo simulation and Personick’ theory was established and the detector prototype was built. Moreover, the signal to noise ratio (SNR) and bit error rate (BER) performance were investigated. Results present that the SNR of 19.8 dB, 29.9 dB and 35.5 dB could be reached for X-ray with the energy of 17 keV, 59.5 keV and 122 keV respectively. This energy response characteristic is much suitable for the X-ray signal detection during spacecraft reentry blackout. Additionally, the deviation of SNR corresponding to the BER between the theoretical and experimental results does not exceed 0.3 dB when the data rate is 100 kbps, which proves the validity of the theoretical model. Furthermore, the numerical analysis shows that the scheme demonstrates high SNR and low BER performance in high bandwidth and low signal receiving power, which explains the superiorities in X-ray signal detection of the design. This work provides the theoretical basis and design reference for the LYSO–SiPM X-ray signal detection module.

In scenarios such as vehicle radioactivity monitoring and unmanned aerial vehicle radioactivity monitoring, the count rate of the γ spectrum detected by the NaI(Tl) detector is low, the characteristic peak is weak, and the statistical fluctuation is large. When such a γ spectrum is processed with the conventional peak-searching method, the characteristic peak recognition accuracy is low and the nuclide identification rate is reduced. A peak-searching method based on the generative adversarial network (GAN) is proposed in this study for low count rate and short-time measurement of a single nuclide γ spectrum. Compared with the symmetric zero-area (SZA) method, the characteristic peak recognition accuracy of the GAN method is improved, the occurrence probability of false peaks is reduced, and the number of false peaks is decreased. Furthermore, the peak position offset with different time measurement conditions of the GAN method is stable. And the performance under shielding conditions of the GAN method is also better than that of the SZA method.

The unmanned aerial vehicle (UAV) radiation monitoring method plays an important role in nuclear accidents emergency. In this research, a spectrum correction algorithm about the UAV airborne radioactivity monitoring equipment NH-UAV was studied to measure the radioactive nuclides within a small area in real time and in a fixed place. The simulation spectra of the high-purity germanium (HPGe) detector and the lanthanum bromide (LaBr 3 ) detector in the equipment were obtained using the Monte Carlo technique. Spectrum correction coefficients were calculated after performing ratio processing techniques about the net peak areas between the double detectors on the detection spectrum of the LaBr 3 detector according to the accuracy of the detection spectrum of the HPGe detector. The relationship between the spectrum correction coefficient and the size of the source term was also investigated. A good linear relation exists between the spectrum correction coefficient and the corresponding energy ( R 2 =0.9765). The maximum relative deviation from the real condition reduced from 1.65 to 0.035. The spectrum correction method was verified as feasible.

In this paper, the low-energy proton-induced single event effect sensitivity of multiple feature size NAND flash memories has been investigated. Under 0.41 MeV proton, the single event effect cross-section peak appeared in 25 nm and 16 nm flash devices. SRIM simulation revealed the primary reason of this phenomenon. Single event upsets caused by direct ionization of low-energy proton could be several orders of magnitude higher than those caused by high-energy proton nuclear reactions. Moreover, the influence of cumulative dose on the single event effect sensitivity of flash device was investigated. As the cumulative dose increased, the single event upset cross-section was increased considerably. This phenomenon appears due to the threshold voltage shift induced by the combination of the proton and the cumulative dose.

In this paper, the bitstream of 28 nm field-programmable-gate-array was resolved. The relationship between the frame address and the resource was obtained. The fault injection platform was designed based on the information of the bitstream which obtained by partial reconfiguration. With this fault injection platform, the equivalence of the global fault and random fault injections was verified. Also, the sensitivities of different circuits were tested by random fault injection. The reinforcement effect of the triple module redundancy for sensitive resources in 28 nm FPGA was also be tested.

Carbon ion therapy is an advanced radiation treatment modality considering its distinct dose distribution and high biological effectiveness. However, carbon ion therapy has become more sensitive to the range uncertainty comparing to the traditional x-ray radiotherapy because of its steep dose distribution near the Bragg peak, which makes the benefits not been fully utilized. Prompt gamma (PG) spectroscopy is one of the potential choices to achieve the range verification in carbon ion therapy. In this paper, we describe that the Doppler shift effect causes the energy shift of PG (4.44 MeV) produced by the de-excitation of the flying 12C*, which makes PG spectroscopy an alternative method for range verification. In order to prove its feasibility of applying this method during patient treatment, Monte Carlo simulation and analytical calculation are compared to verify the accuracy with different materials and non-uniform geometry model. The proposed method is applied to range measurement in the homogeneous phantom filled with different materials (polyethylene, water, and adipose) and the Chinese hybrid radiation phantom with two different irradiated positions (chest and abdomen). Results show that the difference value is less than 2.1% for three homogeneous phantoms. Moreover, good conformance is obtained when using the Chinese hybrid radiation phantom in both irradiated positions. These results prove the feasibility of using the proposed method in a more complicated heterogeneous human model.

A BNCT-dedicated SPECT system to monitor in real time the 10B dose is under development focusing on CdZnTe (CZT) solid state detectors as photon sensors. Since BNCT facilities are characterised by a ( n + γ ) radiation field and considering the high value of cadmium neutron absorption cross section , we evaluated the response of a CZT detector using the irradiation thermal neutron facility of the Pavia University research nuclear reactor. The reported measurements showed that, despite the thermal neutron and γ background, the CZT detector is able to discriminate the 10B signal from the neutron capture peaks of 113Cd.