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The performance of hard X-ray test equipment is an important factor for ground calibration of satellite load detectors. In this paper, the low energy section $(8.3 \sim 38.0$ keV) of hard X-ray single crystal test equipment using standard detector (high purity helium detector) Preliminary performance measurements were taken. It is measured that the energy linearity is 1 at $8.3 \sim 38.0$ keV, the monochromatic light ratio is basically above 90%, the monochromatic luminous flux is substantially greater than 1000 cts/s, and the overall stability is about 0.6%.

At the 4W1B test station of the Synchrotron Radiation Source in Beijing, the composite loss correction factor of the free-radiation ionization chamber of the synchrotron radiation was measured by the 12KeV single-energy X-ray obtained from the twin crystal. The corresponding free air ionization chamber and the traditional method for measuring the composite loss correction factor are introduced. Under the condition of voltage saturation, the method of changing the thickness of the absorption sheet is used to change the dose rate and calculate the composite loss correction factor. The result is shown in The corrected share of the selected 2400V operating voltage is 1.000000048.

A fluorescence X-rays radiation device is established. The device is mainly composed of X-rays machine, fluorescent radiator, secondary filter and beam-limiting diaphragm. It can generate monochromatic X-rays with 8 energy points below 100 keV. The flux is about 106 photon/s. An HPGe detector for X-rays energy spectrum measurement were calibrated using standard radioactive sources, and the relationship between energy and channel was obtained. The Monte Carlo simulation software was used to simulate the detector detection efficiency curve. The primary and secondary radiant energy spectra of the fluorescent radiation device were measured using the HPGe detector, and the fluence rate and energy resolution of the radiation device at different energies were obtained.

In this paper, we mainly study the measurement problem of the half-value layer of the narrow-spectrum (250-600) kV X-ray re-filtering narrow-band, and use the experimental and simulation methods to obtain the half-value layer of the high-energy segment re-filtering narrow spectrum. The half-value layer is one of the important parameter characteristics describing the radiation quality. Therefore, measuring the half-value layer plays an important role in the establishment of the radiation quality. The corresponding specification is not given in the additional filter ISO with a tube voltage greater than 300 kV. The method for determining the additional filter thickness used for the tube voltage greater than 300 kV is to linearly fit the relationship between the tube voltage and the additional filter in ISO, and then calculate the thickness value of the additional filter after 300 kV according to the fitted formula. After determining the thickness value, the corresponding energy spectrum is simulated by Monte Carlo simulation. The energy spectrum simulated by Monte Carlo is compared with the theoretical energy spectrum given in ISO-4037. The results show that the average energy and simulation of N250ISO are obtained. The average energy relative deviation is 0.38%, and the N300 average energy relative deviation is 0.35%. The average energy is within 5% in accordance with ISO specifications. The half-value layer of the narrow spectrum can be re-filtered by the experimental (250-600) kV X-ray by the corresponding method given in ISO.

With the continuous development of Monte Carlo simulation, it provides greater convenience for the reproducibility of X-ray air kerma. The DOSXYZnrc package in the EGSnrc MC simulation program is used to modify the electron loss, scattering fluorescence and pupil edge penetration of the X-ray free air ionization chamber. Monte Carlo simulation is performed by two different approaches. The comparative analysis reveals the use of phase space files. The deviation between the correction factors obtained by the simulation and the correction factors simulated by the effective energy as the single-energy X-ray is substantially within 0.09%, and the deviations of only 70 kV and 240 kV are large, respectively 0.15% and 0.3%. The results show that the correction factors obtained by Monte Carlo simulation of effective energy as single-energy X-ray can also be used to correct the air kerma energy. It is more convenient and fast to simulate the correction factors through effective energy.

At present, we have established the reference radiation with low air-kerma rate,but for the overload characteristics of some instruments, no suitable radiators have been established.Therefore, referring to the new ISO 4037-1:2019 report issued by the International Standard Organization (ISO), a reference radiation of (60-200) kV high air-kerma rate was established.The half-value layer, energy spectrum, mean energy and effective energy of the corresponding radiation are obtained by experiment and simulation., so as to verify the accuracy of the established radiation substance. The establishment of high air kerma rate radiation field provides a standard device for the measurement of some instrument overload characteristics.

The National Institute of Metrology, China(NIM) and the National Metrology Institute of Japan (NMIJ) conducted an international comparison of air kerma in the range of 25-35 KV of mammography. The measurement comparison uses an indirect comparison method. The National Institute of Metrology, as the leading laboratory, uses the molybdenum target reference free air ionization chamber to perform absolute measurement of (25~35) KV X-ray air kerma, and then under the same conditions. Pass the ionization chamber for calibration and give the scale factor. The ionization chamber is then calibrated in the radiation field of the other laboratory. The transfer ionization chamber was measured using a flat ionization chamber RC6M10167 from December 2018 to January 2018 under BIPM reference conditions. The deviation of the comparison results is between 0.3% and 0.4%.1

A monochromatic X-ray optics system has been developed in this study which would mainly been used to calibrate the satellite-borne detectors. The system consists of four parts, including the X-ray source, the collimating system, the monochromator, and X-ray detectors. In particular, an algorithm has been proposed to diagnose spot size of monochromatic X-ray optics system. As a comparison, two methods were adopted to diagnose the spot size. Experimental results shows that the method and algorithm to diagnose spot size is feasible. This work will be helpful to research on spot size diagnosis of X-ray optics system, and would contribute to the calibration on ground of satellites-borne detectors.

In this project, the comparison between EGSnrc simulation and HPGE detector to obtain X-ray emission spectrum characteristics. The main purpose of this paper is to compare the advantages and disadvantages of two methods of obtaining new standard radiant mass spectrometry in order to obtain a precise method to measure whether the newly established radiant mass meets the requirements. The newly established X-ray radiation materials need to meet certain specifications. Among them, the average energy of radiation, half-value layer and homogeneity coefficient are the key factors. In general, the half-value layer is obtained by the actual measurement of the ionization current with different thickness after additional filtration; The resolution, maximum energy and average energy of energy spectrum are obtained by analyzing the energy spectrum of radiation. The energy spectrum of radiation is obtained by means of practical measurement by spectrometer and simulation by EGSnrc monte carlo method. The practical measurement of spectrometer and the simulation of EGSnrc monte carlo method have their own limitations. Through the analysis of experimental results, the energy spectrum below 10keV can only be measured by the spectrometer, because the minimum energy of EGSnrc is 10keV. The energy spectrum of EGSnrc simulation is in good agreement with the recommended value. The energy spectrum measured by the spectrometer will measure the scattering and characteristic peaks to some extent. So we should pay attention to the influence of characteristic peak and scattering on energy spectrum.

The main purpose of this paper is to calibrate the detection efficiency and energy linearity of a hard X-ray imager (HXI), one of the payloads on the ASO-S satellite. In this experiment, HPGe calibrated by radioactive source was used as the standard detector, and the experimental device used was a double crystal calibration device. The experimental method is to first measure the single energy peak of the corresponding energy point with a standard detector, and then use the HXI LaBr3 crystal detector probe to obtain the same single energy peak. It should be noted here that in order to eliminate the statistical fluctuations and other factors, we set the detection time of both detectors to 1000 seconds. Then, the dobule crystal parallelism is detuned (ie, non-parallel) to measure the unfiltered background and the electronic noise. Finally, the open source software Root is used to perform relatively clean single-energy X-ray beam data obtained after subtracting the background data of the beam.

In this paper, the energy linear scale and detection efficiency scale of a chromium telluride detector are studied. The high-purity germanium detector of the standard detector can accurately know the energy and intensity of the single energy peak, and then scale the energy linearity and detection efficiency of the chromium telluride detector. The linear correlation coefficient of the energy is close to 1. The efficiency curve of chromium telluride was obtained from MCke simulation from 6 keV to 150 keV. The experimental results were compared with the calculated results, and the relative deviation was within 1.2%.The device used in this experiment is a single crystal monochromator. Compared with the binary star monochromator, the single crystal monochromator has the characteristics of easy light emission, large flux, constant light output direction and stable stability. Different optical machine target materials will produce different energy spectra, and the energy spectrum shape determines the energy range and fluence of the generated single energy X-rays. After experimental testing, when the target material is a copper target, a higher fluence photon can be produced below 20 keV. The standard detector used is a high-purity germanium detector with high sensitivity and high energy resolution that has been scaled by the source.

Scientific satellites can effectively detect astronomy. Accurate ground calibration experiments are required on the detector before the satellite payload is completed. Through the X-ray energy spectrum detected by the high-purity germanium detector, the energy resolution and energy response of the energy spectrum can be studied to meet the ground calibration requirements of the gravitational wave electromagnetic counterpart all-weather monitor (GECAM satellite). This paper mainly introduces the performance study of the X-ray high-energy part of the GRD detector, and conducts preliminary calibration experiments on the energy range from 80Kev to 150Kev. The test results: the high-purity enthalpy of the standard detector and the GRD detector have good energy linearity; The energy resolution of the single-energy X-ray of the GRD detector is better than 10.2%@79.9keV, which has good monochromaticity.

Absolute measurement of high fluence rate X-ray dose was required in thermonuclear fusion research and plasma diagnostic measurement. An ionization chamber used for the reproducibility of air-kerma in high fluence rate X-rays was designed, and the monoenergetic X-rays of (6-20) keV were absolutely measured on Beijing Synchrotron Radiation Facility. The air attenuation and recombination correction factors of the free-air ionization chamber were obtained experimentally. Thus, the air-kerma for the $(6 \sim 20)$ keV monoenergetic X-rays can be determined.

In order to meet the ground calibration requirements of Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) satellite gamma ray detector (GRD), two sets of single-energy x-ray calibration devices were established in China Metrology Institute (Changping). One set is a single crystal calibration device, and LiF crystal can realize continuous emission of (8.1-37.9) keV single-energy X-ray; The other set is a dual crystal calibration device. Si220 crystal and Si551 crystal can realize continuous light emission of single energy x-ray in the energy range of (38-160) keV. The X-ray energy spectrum, energy resolution and energy response of the calibration device were studied by standard high-purity germanium detectors. The test results show that the energy range of the calibration device is: (8-160) keV; monochromaticity: energy resolution 3.1%@8.1keV, 10.2%@79.9keV; monochromatic luminous flux 649cts/s@38. 0keV,678cts/s@79.9keV,298cts/s@121.8keV; monochromatic light ratio 96%@38.0keV, 97%@79.9keV, 96%@121.8keV. Combined with the actual test results of the energy point of the GRD, it indicates that the calibration device can meet the calibration requirements of the GRD.

Based on the low-energy X-ray reference the (10-40)kV narrow-spectrum series of radiation masses are established, and the radiation field size and radiation field uniformity are measured. The results show that the field uniformity is better than 99% in all directions, and the radiation field range is about 50cm.The first half-value layer, the secend half-value layer and the homogeneity coefficient of the established radiation quality were measured and two scattered radiation experiments were carried out. Experiment 1 measures the air kerma rate at various points in the central axis of the X-ray beam. The results show that the dose rate satisfies the inverse square law and the smaller the tube voltage, the smaller the error. In experiment 2, the radiation field range was completely covered with lead with a thickness of 3 cm. The air kerma rate at various points in the central axis of the measurement showed that the effect of scattered radiation on the total dose rate did not exceed 2%. The X-ray energy spectrum of the subsurface under radiation was simulated by EGSnrc software, and the parameters such as average energy and resolution were calculated and compared with the national standard GB/T12162.1. The results show that the simulated radioactive energy spectrum is basically consistent with the national standard. The average energy and spectral resolution deviation is not more than 3%, and the established radiation quality meets the requirements.

The energy response function of neutron dosimeter is directly related to the accuracy of its dose monitoring value. Simulation using Monte Carlo software is an effective method to determine the energy response function of neutron dosimeter. Based on the Monte Carlo calculation results, the structure of two kinds of neutron dosimeters suitable for environmental monitoring and radiation field monitoring are determined. The characteristics of high voltage curve and n-γ resolution of the dosimeters are studied experimentally. The experiments are carried out under the single energy neutron source which is generated by accelerator. The experimental results are in good agreement with the simulation results.

Mammography x-rays standard is basis of improving the quality of mammary machine and reduce the radiation dose of women and medical staff. The molybdenum target x-rays machine is used as the radiation source, and free-air chamber is designed for detecting photons. Refer to international standards file four standard radiation qualities are established. The spectrum of the four radiation qualities are simulated using EGSnrc, which are used as the source in the calculation of correction factors. The free-air correction factors for electron loss, photon scatter and fluorescence are calculated using the Monte Carlo simulation software EGSnrc. The calculation results are compared with other national metrology institute, the deviation is within 0.53%.

The main aim of this paper is to develop a superior fault detection and isolation scheme (FDI) for the attitude sensor of a satellite. Towards this end, we present a generic data-driven prognostics framework utilized improved central divided-difference Kalman filter (CDKF) algorithm proposed in our previous work for fault detection and combine RBF neural network with fuzzy logic for fault identification process. The proposed method is applied to the micro satellite which employs three-axis magnetometer (TAM) and fiber optic gyroscope (FOG) as attitude sensors. Two types of the typical sensor fault scenarios are considered in the paper. The simulation studies demonstrate that our method shows better performance and capabilities, and thus is a good candidate for on-board fault diagnosis scheme for attitude sensors of satellite.

In this paper, an improved Central divided-Difference Kalman Filter (CDKF) algorithm for the satellite that adopts three-axis magnetometer (TAM) and a fiber optic gyroscope (FOG) as attitude sensors is proposed. First, to overcome the disadvantages of Extended Kalman Filter (EKF), which is widely used as the attitude determination technique of satellites at the present, we present Central divided-Central Kalman Filtering (CDKF) algorithm applicable on the basis of the discretization kinematics equation of satellite, and applicable to attitude determination of this type of satellite. Then, considering the uncertainties and external disturbances on the system, we utilize RBF neural network to adjust the filtering gain online. Finally, a comparative simulation experiment is provided to show that our RBF-CDKF algorithm is able to achieve greater estimation performance than EKF and CDKF.

The spacecraft flight dynamics simulator for control is a laboratory system designed for the purpose of developing and testing orbit and attitude control algorithms in a low-risk, low-cost environment. This paper presents the details for the design and construction of a new spacecraft flight dynamics control simulator, including hardware and software architecture. The distinguished feature of the simulator different from other simulators is that on-board data handling is based on wireless ad hoc network, which breaks through the traditional conception. The major issues encountered during the realization of the simulator and the approaches developed to remedy these difficulties are discussed in detail(such as modeling and simulating sensors measurements and actuators control commands, the data communication on the wireless ad hoc network, the process synchronization of the wireless node, the real-time visualization animation by driving STK). Finally, based on the established simulator, the paper presents some experimental results from the application of large angle attitude maneuver. The test results demonstrate the validity and correctness of the simulator.