Nondestructive technique for identifying nuclides using neutron resonance transmission analysis at CSNS Back-n

Nondestructive and noninvasive neutron assays are essential applications of neutron techniques.Neutron resonance transmission analysis(NRTA)is a powerful nondestructive method for investigating the elemental composition of an object.The back-streaming neutron line(Back-n)is a newly built time-of-flight facility at the China Spallation Neutron Source(CSNS)that provides neutrons in the eV to 300 MeV range.A feasibility study of the NRTA method for nuclide identification was conducted at the CSNS Back-n via two test experiments.The results demonstrate that it is feasible to identify different elements and isotopes in samples using the NRTA method at Back-n.This study reveals its potential future applications.

Efficient and selective extraction of uranium from seawater based on a novel pulsed liquid chromatography radionuclide separation method

The novel pulsed liquid chromatography radionuclide separation method presented here provides a new and promising strategy for the extraction of uranium from seawater.In this study,a new chromatographic separation method was proposed,and a pulsed nuclide automated separation device was developed,alongside a new chromatographic column.The length of this chromatographic column was 10 m,with an internal warp of 3 mm and a packing size of 1 mm,while the total separation units of the column reached 12,250.The most favorable conditions for the separation of nuclides were then obtained through optimizing the separation conditions of the device:Sample pH in the column=2,sample injection flow rate=5.698 mL/min,chromatographic column heating temperature=60℃.Separation experiments were also carried out for uranium,europium,and sodium ions in mixed solutions;uranium and sodium ions in water samples from the Ganjiang River;and uranium,sodium,and magnesium ions from seawater samples.The separation factors between the different nuclei were then calculated based on the experimental data,and a formula for the separation level was derived.The experimental results showed that the separation factor in the mixed solution of uranium and europium(1:1)was 1.088,while achieving the initial separation of uranium and europium theoretically required a 47-stage separation.Considering the separation factor of 1.50for the uranium and sodium ions in water samples from the Ganjiang River,achieving the initial separation of uranium and sodium ions would have theoretically required at least a 21-stage separation.Furthermore,for the seawater sample separation experiments,the separation factor of uranium and sodium ions was 1.2885;therefore,more than 28 stages of sample separation would be required to achieve uranium extraction from seawater.The novel pulsed liquid chromatography method proposed in this study was innovative in terms of uranium separation and enrichment,while expanding the possibilities of extracting uranium from seawater through chromatography.

Determining topographic shielding from digital elevation models for cosmogenic nuclide analysis: a GIS model for discrete sample sites

Topographic shielding(TS) is an important factor in cosmogenic nuclide surface exposure dating. The development of geographic information systems(GIS) and the availability of digital elevation models(DEMs) make it possible to derive this factor directly from a DEM. Most available GIS models derive the TS factors for an area(all cells in a DEM) without the consideration of surface conditions of individual sites, such as the strike, dip,and height above ground, into the calculation. This paper presents a new GIS model to derive the TS factors for discrete sample sites. This model uses the Skyline and Skyline Graph functions in ArcGIS to extract the set of azimuth and elevation angles of topographic obstructions around each site from a DEM(considering the sample height above ground)and then incorporates the strike and dip information of the sample surface to derive the TS factor. All processing tools and steps are streamlined in ArcGIS modelbuilder and this model can be run like a standard ArcGIS geoprocessing tool. It provides an easy and user-friendly means to derive the TS factors for discrete samples based on a DEM and the measured strike, dip and sample height for each site.

Comparative Proteomic Analysis of Human Benign Prostatic Hyperplastic Tissue Before and After Irradiation with Radioactive Nuclide

The expressed proteins were extracted from human benign prostatic hyperplastic tissues obtained with transurethral resection of the prostate before and after their irradiation with radioactive nuclide. The proteins were separated by two-dimensional gel electrophoresis and analyzed by mass spectrometry. Four proteins were differentially expressed and were identified with a database search. Three were associated with the regulation of cell motion and one was lactate dehydrogenase B, which plays an important role in the process of cell energy metabolism and cell state changes in tissue. The comparative proteomic analysis indicates that after irradiation with radioactive nuclide, changes occur in human benign prostatic hyperplastic cells, and associated proteins are expressed. Analysis of these proteins should help to identify the mechanism involved when human prostatic hyperplasia is treated by irradiation with radioactive nuclide.

Fast nuclide identification based on a sequential Bayesian method

The rapid identification of radioactive substances in public areas is crucial.However,traditional nuclide identification methods only consider information regarding the full energy peaks of the gamma-ray spectrum and require long recording times,which lead to long response times.In this paper,a novel identification method using the event mode sequence(EMS)information of target radionuclides is proposed.The EMS of a target radionuclide and natural background radiation were established as two different probabilistic models and a decision function based on Bayesian inference and sequential testing was constructed.The proposed detection scheme individually processes each photon.When a photon is detected and accepted,the corresponding posterior probability distribution parameters are estimated using Bayesian inference and the decision function is updated.Then,value of the decision function is compared to preset detection thresholds to obtain a detection result.Experiments on different target radionuclides(137Cs and 60Co)were performed.The count rates of the regions of interest(ROI)in the backgrounds between[651,671],[1154,1186],and[1310,1350]keV were 2.35,5.14,and 0.57 CPS,respectively.The experimental results demonstrate that the average detection time was 6.0 s for 60Co(with an activity of 80400 Bq)at a distance of 60 cm from the detector.The average detection time was 7 s for 137Cs(with an activity of 131000 Bq)at a distance of 90 cm from the detector.The results demonstrate that the proposed method can detect radioactive substances with low activity.

Determining Topographic Shielding from Digital Elevation Models for Cosmogenic Nuclide Analysis:a GIS Approach and Field Validation

Topographic shielding of cosmic radiation flux is a key parameter in using cosmogenic nuclides to determine surface exposure ages or erosion rates.Traditionally,this parameter is measured in the field and uncertainty and/or inconsistency may exist among different investigators.This paper provides an ArcGIS python code to determine topographic shielding factors using digital elevation models(DEMs).This code can be imported into ArcGIS as a geoprocessing tool with a user-friendly graphical interface.The DEM-derived parameters using this method were validated with field measurements in central Tian Shan.Results indicate that DEM-derived shielding factors are consistent with field-measured values.It provides a valuable tool to save fieldwork efforts and has the potential to provide consistent results for different regions in the world to facilitate the comparison of cosmogenic nuclide results.

DEPTH PROFILING OF RADIOACTIVE NUCLIDES IN SOIL

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Simulation of experimental spectra for medium-heavy nuclides in accelerator mass spectrometry

Some interferences are often encountered in accelerator mass spectrometry (AMS) measurements, espe-cially for medium-heavy nuclide measurement. It is difficult for online discrimination of the nuclide of interest from the interfering ones. In order to solve this problem, we developed a method to simulate the experimental spectra of medium-heavy nuclides in AMS measurements. The results obtained from this method are in good agreement with experimental values.

Predicting the Binding Energies of the 1s Nuclides with High Precision, Based on Baryons which Are Yang-Mills Magnetic Monopoles

In an earlier paper, the author employed the thesis that baryons are Yang-Mills magnetic monopoles and that proton and neutron binding energies are determined based on their up and down current quark masses to predict a relationship among the electron and up and down quark masses within experimental errors and to obtain a very accurate relationship for nuclear binding energies generally and for the binding of 56Fe in particular. The free proton and neutron were understood to each contain intrinsic binding energies which confine their quarks, wherein some or most (never all) of this energy is released for binding when they are fused into composite nuclides. The purpose of this paper is to further advance this thesis by seeing whether it can explain the specific empirical binding energies of the light 1s nuclides, namely, 2H, 3H, 3He and 4He, with high precision. As the method to achieve this, we show how these 1s binding energies are in fact the components of inner and outer tensor products of Yang-Mills matrices which are implicit in the expressions for these intrinsic binding energies. The result is that the binding energies for the 4He, 3He and 3H nucleons are respectively, independently, explained to less than four parts in one million, four parts in 100,000, and seven parts in one million, all in AMU. Further, we are able to exactly relate the neutron minus proton mass difference to a function of the up and down current quark masses, which in turn enables us to explain the 2H binding energy most precisely of all, to just over 8 parts in ten million. These energies have never before been theoretically explained with such accuracy, which leads to the conclusion that the underlying thesis provides the strongest theoretical explanation to date of what baryons are, and of how protons and neutrons confine their quarks and bind together into composite nuclides. As is also reviewed in Section 9, these results may lay the foundation for more easily catalyzing nuclear fusion energy release.

Residual Nuclides Induced in Cu Target by a 250 MeV Proton Beam

Residual nuclide production is studied experimentally by bombarding a Cu target with a 250 MeV proton beam. The data are measured by the off-line γ-spectroscopy method. Six nuclides are identified and their cross sections are determined. The corresponding calculated results by the MCNPX and GEANT4 codes are compared with the experimental data to check the validity of the codes. A comparison shows that the MCNPX simulation has a better agreement with the experiment. The energy dependence of residual nuclide production is studied with the aid of MCNPX simulation, and it is found that the mass yields for the nuclides in the light mass region increase significantly with the proton energy.

Existence of the fifth unstable nuclided series

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5-1 Introduction to Code System COUPLE3.0 for Neutron Transport and Nuclides Burn-up Analyses

The code system COUPLE2.0[1] was developed by the Institute of Nuclear and New Energy Technology (INET) of Tsinghua University, which can be used for coupled neutron transport and nuclide burn-up analyses of Accelerator Driven sub- critical reactor System(ADS). The Institute of Modern Physics, Chinese Academy of Sciences imported the code system in 2014, and developed the version COUPLE3.0 according to the requirements of new function and preliminary verifications based on the fast reactor and ADS benchmarks were done.

An Effective Method for Studying Heavy Neutron-Rich Nuclide

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THE ADVANCES IN SYNTHESIS AND STUDY OF NEW NUCLIDES IN CHINA

This paper introduces the importance of synthesis and study of new nuclides far from the stability line. Following the example of new nuclides 208Hg, 185Hf and 237Th, which were synthesized for the first time by the scientists in the Institute of Modern Physics, the progress of physics and technology in this aspect in our country are summarized. This paper also outlines a proposal about farther development of the synthesis and study of new nuclides and the construction of relevant key facilities in our country at the beginning of the next century.

THE DECAY DIAGRAMS OF TWO NEW NUCLIDES ESTABLISHED BY CHINA FOR THE FIRST TIME IN THE WORLD Lanzhou Institute of Modern Physics, CAS

The decay diagrams of radioactive nuclei are the obvious indication of the main properties shown by the nuclei at low states of excitement and of the basic aspects of nuclear physics.They are extensively applied in industry’,agriculture,energy,national defense,medical science,the environment,and metrology,as well as in astronomy,archaeology,geology,biology,chemistry and other basic sciences.Therefore,they are always focuses of interest.