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A neutron detector, based on scintillator and Cherenkov detector, was designed to monitor the D-T neutron generator in a PGNAA online measurement system in our previous study. In this paper, the foil activation method was used to study the intrinsic detection efficiency of the detector to the D-T neutron generator. The Fe foil with 99.99% purity was selected as the activation foil. The experiments and the GEANT4 simulations were carried out to study the intrinsic detection efficiency of the monitor. The results show that the intrinsic detection efficiency of the monitor is 20.42% ± 0.76%. Then, the calibrated detector and Fe foils were simultaneously used to measure the neutron flux of D-T neutron generator. The relative deviation between the results of the two methods is 5.64%.

A new type of neutron detector, which consists of polyethylene, an EJ200 plastic scintillator and fused silica, was proposed and optimized by the GEANT4 Monte Carlo simulation toolkit in our previous studies. The calculation method was also described for calculating the neutron flux in the preset condition. This paper reports the manufacturing of the prototype detector. Experiments are conducted to validate the feasibility of this detector. A D–T neutron generator and a 60 Co gamma-ray source are used in the experiments. The designed detector and a He-3 proportional counter are simultaneously used to monitor the yield of the D–T neutron generator. A more universal calculation method is developed to enable the application of this detector to common conditions. The experimental results show that the performance of the designed detector is comparable to that of the He-3 proportional counter. The relative deviations between their normalized counts are less than 5%.

A prompt gamma ray neutron activation analysis detection system was developed to detect the heavy metals in sediments by using an 241Am-Be neutron source and BGO detector. The samples containing cadmium and mercury were used to test the performance of setup. The linear relationship between prompt gamma ray counts and the concentrations was studied. The results showed the counts of the prompt gamma rays from cadmium do not increase linearly with its concentrations, while the prompt gamma ray counts from Hg vary nearly linearly with the concentrations, due to the neutron self-shielding. Then a method was used to correct the effect and the non-linearly response was restored after the correction. And the minimum detectable concentration of Cd and Hg were 52.8 (at 8.484 MeV) and 81.6 (at 5.967 MeV) ppm, respectively.

A new method is proposed to detect fast neutron flux: the neutron-induced X-ray fluorescence method. In this method, the neutrons are firstly converted to charged particles, and then the charged particles interact with the target to generate the characteristic X-ray fluorescence. Finally, the Kα X-ray emission from the target is detected for measurement of the neutron flux. On the basis of this method, the structure of the detection device is designed: it is composed mainly of a layer of a fast neutron converter and a layer of the target. The Geant4 Monte Carlo simulation toolkit is used to optimize the detection device. According to the simulation results, the detection device is manufactured so as to perform the feasibility verification experiments. In the experiments, a D-T neutron generator is used as the neutron source, and the number of neutrons is changed in two ways: by change of the working voltage of the neutron generator or by change of the measurement time. The experimental results show that there is a good linear relationship between the number of neutrons and the Kα X-ray counts when the measurement time is changed. When the working voltage of the neutron generator is changed, a 3He proportional counter is used as a reference detector. The results show that the trend of the Kα X-ray counts is in good agreement with the trend for the 3He proportional counter. It is proved that this method is feasible for fast neutron flux measurement.

Particulate matters, gaseous chemicals, and heavy metals emitted from industrial processes into the environment could be directly transmitted to humans through air inhalation. In order to accurately estimate health risk and control the source of pollution caused by cement raw meal, an online X-ray fluorescence analyzer system, consisting of an X-ray fluorescence analyzer with data acquisition software and a laser rangefinder, was developed to carry out the measurement of heavy metals in cement raw meal. The X-ray fluorescence analyzer was mounted on a sled, which can effectively smooth the surface of cement raw meal and reduce the impact of surface roughness during online measurement. The laser rangefinder was mounted over the sled for measuring the distance between cement raw meal sample and the analyzer. Several heavy metals and other elements in cement raw meal were online measured by the X-ray fluorescence analyzer directly above a conveyor belt. The limits of detection for Pb, Cr, Fe, Ti, Ca,...

A new prompt-gamma neutron activation analysis (PGNAA) setup has been designed for element determination in aqueous solution with a 300 mCi 241 Am–Be neutron source and a 4 in.×3 in. (diameter×height) BGO detector, uncooled. A polyethylene cylindrical sample container approximately 40 cm in outer radius and 80 cm in height was used. To reduce the neutron dose in the detector, a block of 5 cm thickness Li 2 CO 3 was placed between the source and the detector for separation, but no gamma-blocker was used. By adjusting the position of the detector and optimizing the geometrical conditions of the setup, the element detection limit with a low activity neutron source was further improved. This methodology was checked by simulations with chlorine, mercury and cadmium determination and by experiments with chlorine determination in aqueous samples. The results show a good linear relationship between chlorine concentration and the count of its characteristic peak, and the detection limit of chlorine can reach 41.7 mg/L with a collection time of 3600 s for each spectrum. Additionally, a linear relationship was identified between mercury concentration and the count of its characteristic peak, but for cadmium, a non-linear relationship was observed in the simulations.

A laboratory investigation of the radiation-induced degradation of aniline by gamma irradiation is the subject of this paper. During the inquiry, several aqueous samples with aniline concentrations of 25, 50, 75, 100 and 200 mg/L were irradiated for 5, 10, 15, 20, 25 and 30 h, respectively, by a

Heavy metals in haze episode will continue to threaten the quality of public health around the world. In order to decrease the emission of heavy metals produced from coal burning, an online X-ray fluorescence (XRF) analyzer system, consisting of an XRF analyzer with data acquisition software and a laser rangefinder, was developed to carry out the measurement of heavy metals in pulverized coal. The XRF analyzer was mounted on a sled, which can effectively smooth the surface of pulverized coal and reduce the impact of surface roughness during online measurement. The laser rangefinder was mounted over the sled for measuring the distance between a pulverized coal sample and the analyzer. Several heavy metals and other elements in pulverized coal were online measured by the XRF analyzer directly above a conveyor belt. The limits of detection for Hg, Pb, Cr, Ti, Fe, and Ca by the analyzer were 44 ± 2, 34 ± 2, 17 ± 3, 41 ± 4, 19 ± 3, and 65 ± 2 mg·kg–1, respectively. The relative standard deviation (%RSD) for the elements mentioned was less than 7.74%. By comparison with the results by inductively-coupled plasma mass spectrometry (ICP-MS), relative deviation (%D) of the online XRF analyzer was less than 10% for Cr, Ti, and Ca, in the range of 0.8–24.26% for Fe, and greater than 20% for Hg and Pb.