Molecular mechanisms of neutron radiation dose effects on M1 generation peas.

The dose effect of radiation has long been a topic of concern, but the molecular mechanism behind it is still unclear. In this study, dried pea seeds were irradiated with 252Cf fission neutron source. Through analyzing the transcriptome and proteome of M1 generation pea (Pisum sativum L.) leaves, we studied the molecular rule and mechanism of neutron dose effect. Our results showed three important rules of global gene expression in the studied dose range. The rule closely related to the neutron absorbed dose at the transcription and translation levels is: the greater the difference in neutron absorbed dose between two radiation treatment groups, the greater the difference in differential expression between the two groups and the control group. We also obtained important sensitive metabolic pathways of neutron radiation, as well as related key genes. Furthermore, the overall molecular regulation mechanism of dose effect was revealed based on the main functional items obtained. Our research results can be applied to appropriate radiation dose estimation and agricultural production practice.

Study on neutron energy spectrum unfolding algorithm with EJ309 liquid scintillation detector.

Proton recoil method can be used to experimentally measure fast neutron energy spectrum of non-pulsed neutron sources. The neutron energy spectrum unfolding algorithms based on the MLEM method, the GOLD deconvolution method, the Direct-D method, have been developed by using the EJ309 liquid scintillation detector. The degree of iteration by the mean square error (MSE) is proposed as a judgment criterion by according to the iterative accuracy, convergence speed and iteration efficiency. The developed neutron energy spectrum unfolding algorithms can unfolding the standard simulated mono-energetic neutron spectrum (2.5 MeV), 252Cf neutron spectrum, Am-Be neutron spectrum and the experimentally measured D-D neutron spectrum with higher precision as well as fewer iterations. The unfolded neutron spectra are in good agreement with the standard simulated neutron spectra and evaluated D-D neutron spectrum, which is revealed that the developed unfolding algorithms can unfolding neutron energy spectrum with reasonable accuracy.

Production of medical isotope 68Ge based on a novel chromatography separation technique and assembling of 68Ge/68Ga generator.

A double-column chromatography separation technique was involved for isolation of 68Ge from a bombarded Ga-Ni alloy target. About 185 MBq 68Ge obtained was used for assembling SnO2-based 68Ge/68Ga generator. Approximately 70% of 68Ga in high radioactivity concentration was eluted from generator with excellent radionuclidic, radiochemical and chemical purity. 68Ga was quite adequate for radiolabeling with DOTATATE or PSMA-617 with a high labelling efficiency of >92%. The double-column chromatography technique possessed a potential application prospect of 68Ge/68Ga production, aiding the development of 68Ga in nuclear medicine.

In situ experimental measurement of mercury by combining PGNAA and characteristic X-ray fluorescence.

In our previous research, a new detection method was proposed to measure Hg and Pb simultaneously by combining Prompt Gamma-ray Neutron Activation Analysis (PGNAA) and X-ray Fluorescence (XRF) and proved by the Monte Carlo N-Particle (MCNP) simulation code. For further experimental verification, a combined measurement experimental facility, comprising an 241Am-Be neutron source, SAINT-GOBAIN Bismuth Germanate (BGO) as the γ-ray detector, and an NaI detector with 25 µm Be window as the X-ray detector, was presented. Specifically, the characteristic X-ray fluorescence of the Hg directly induced in this experimental facility was utilized to improve the limits of detection (LOD) of Hg instead of traditional excitation sources. The simulation and experiment results indicated that LOD for Hg by the combined measurement instrument was 19.4 mg kg-1. The empirical formula of the calibration curve in this method was given based on the aforementioned calculations.

Study on the Relationship between Seed Absorbed Dose and Seed Composition of 252Cf Neutron Source Irradiated Bean Seed.

This study aims to further identify the biological effects of neutron-irradiated plants and provides insights into the mutation breeding of such plants. In this study, the neutron irradiation device designed by our institute was used to analyze the relationship between the seed components in different legume crops and their neutron absorption dose rate, fission gamma absorption dose rate, and induced gamma absorption dose rate. The results show that the effect sizes of the components on the neutron absorbed dose rate are as follows: ash > fat > moisture > carbohydrate > protein. The effect sizes of the components on the absorbed dose rate of fission gamma are as follows: ash > moisture > fat > carbohydrate > protein. There is a positive correlation between fission gamma absorbed dose rate and the weight of ash, water and fat, while a negative correlation with carbohydrate and protein. However, the linear relationship between each component and the absorbed dose rate of induced gamma is not significant, this needs to be identified by further researches. Based on the results of the present study, we conclude that the neutron absorbed dose can be calculated without taking into account the fat composition of bean crop seeds (except for soybean seeds) in the process of mutation breeding induced by radiation. In special cases where the accuracy requirement of the dose rate is not high, it is possible to use protein instead of legume crop seeds for neutron absorption dose calculations.

250 kV 6 mA compact Cockcroft-Walton high-voltage power supply.

A compact power supply system for a compact neutron generator has been developed. A 4-stage symmetrical Cockcroft-Walton circuit is adopted to produce 250 kV direct current high-voltage. A 2-stage 280 kV isolation transformer system is used to drive the ion source power supply. For a compact structure, safety, and reliability during the operation, the Cockcroft-Walton circuit and the isolation transformer system are enclosed in an epoxy vessel containing the transformer oil whose size is about ∅350 mm × 766 mm. Test results indicate that the maximum output voltage of the power supply is 282 kV, and the stability of the output voltage is better than 0.63% when the high voltage power supply is operated at 250 kV, 6.9 mA with the input voltage varying ±10%.

A high-current microwave ion source with permanent magnet and its beam emittance measurement.

The progress of a 2.45 GHz high-current microwave ion source with permanent magnet for T(d,n)4He reaction neutron generator is reported in this paper. At 600 W microwave power and 22 kV extraction voltage, 90 mA peak hydrogen ion beam is extracted from a single aperture of 6 mm diameter. The beam emittance is measured using a simplified pepper-pot method. The (x,x(')) emittance and the (y,y(')) emittance for 14 keV hydrogen ion beam are 55.3pi and 58.2pi mm mrad, respectively. The normalized emittances are 0.302pi and 0.317pi mm mrad, respectively.