To develop a NaI （T1） detector for in situ radioactivity monitoring in the marine environment and enhance the confidence of the probability of the gamma-spectrum analysis, Monte Carlo simulations using the Monte Car...To develop a NaI （T1） detector for in situ radioactivity monitoring in the marine environment and enhance the confidence of the probability of the gamma-spectrum analysis, Monte Carlo simulations using the Monte Carlo N-Particle （ MNCP ） code were performed to provide the response spectra of some interested radionuclides and the background spectra originating from the natural radionuclides in seawater recorded by a NaI （T1） detector. A newly developed 75 mm × 75 mm NaI （T1） detector was calibrated using four reference radioactive sources 137Cs, 60Co, 40K and 54Mn in the laboratory before the field measurements in seawater. A simulation model was established for the detector immersed in seawater. The simulated spectra were all broadened with Gaussian pulses to reflect the statistical fluctuations and electrical noise in the real measurement. The simulated spectra show that the single-energy photons into the detector are mostly scattering low-energy photons and the high background in the low energy region mainly originates from the Compton effect of the high energy y-rays of natural radionuclides in seawater. The simulated background spectrum was compared with the experimental one recorded in field measurement and they seem to be in good agreement. The simulation method and spectra can be used for the accurate analysis of the filed measurement results of low concentration radioactivity in seawater.展开更多
In the last years, the production of optical fibers cables has made possible the development of a range of spectroscopic probes for in situ analysis performing beyond nondestructive tests, environmental monitoring, se...In the last years, the production of optical fibers cables has made possible the development of a range of spectroscopic probes for in situ analysis performing beyond nondestructive tests, environmental monitoring, security investigation, application in radiotherapy for dose monitoring, verification and validation. In this work, a system using an optical fiber cable to electromagnetic signal transmission from a NaI（TI） radiation detector is presented. The innovative device takes advantage mainly of the optical fibers large passband, small signal attenuation and immunity to electromagnetic interference to application for radiation detection systems. The main aim was to simplify the detection system making it to reach areas where the conventional device cannot access due to its lack of mobility and external dimensions. Some tests with this innovative system are presented and the results stimulate the continuity of the researches.展开更多
A precision measurment of inclusive electron scattering cross sections is carried out at Jefferson Lab in the quasi-elastic region for 4 He, 12 C, 56 Fe and 208 Pb targets. The longitudinal （R L ） and transverse （R...A precision measurment of inclusive electron scattering cross sections is carried out at Jefferson Lab in the quasi-elastic region for 4 He, 12 C, 56 Fe and 208 Pb targets. The longitudinal （R L ） and transverse （R T ） response functions of the nucleon need to be extracted precisely in the momentum transfer range 0.55 GeV/c≤ ｜ q ｜ ≤1.0 GeV/c. To achieve the above goal, a NaI （Tl） calorimeter is used to distinguish good electrons from background, including pions and low energy electrons rescattered from the walls of the spectrometer magnets. Due to a large set of kinematics and changes in HV settings, a number of calibrations are performed for the NaI （Tl） detector. Corrections for a few blocks of NaI （Tl） with bad or no signal are applied. The resolution of the NaI （Tl） detector after calibration reached δE/E^（1/2） ≈ 3% at E=1 GeV. The performance of the NaI （Tl） detector is compared with a simulation. The good calibration and background analysis for the NaI（Tl） detector are very important for the reduction of the systematic error of cross sections and the separation of R L and R T .展开更多
Understanding the radiation background at the north crossing point （NCP） in the tunnel of BEPCII is crucial for the performance safety of the High Purity Germanium （HPGe） detector, and in turn of great significanc...Understanding the radiation background at the north crossing point （NCP） in the tunnel of BEPCII is crucial for the performance safety of the High Purity Germanium （HPGe） detector, and in turn of great significance for long-term stable running of the energy measurement system. Therefore, as the first step, a NaI（T1） detector is constructed to continuously measure the radiation level of photons as background for future experiments. Furthermore, gamma and neutron dosimeters are utilized to explore the radiation distribution in the vicinity of the NCP where the HPGe detector will be located. Synthesizing all obtained information, the shielding for neutron irradiation is studied based on model-dependent theoretical analysis.展开更多
The technique details for measuring radiation dose are expounded. The results of gamma and neutron radiation levels are presented and the corresponding radiation shielding is discussed based on the simplified estimati...The technique details for measuring radiation dose are expounded. The results of gamma and neutron radiation levels are presented and the corresponding radiation shielding is discussed based on the simplified estimation. In addition, the photon radiation level move as background for future experiments is measured by a NaI（T1） detector.展开更多
基金financial support from the International Science & Technology Cooperation Program of China (No. 2013DFR90220)National Natural Science Foundation of China (No. 41206076)Qingdao Applied Basic Research Project (NO. 14-2-4-94-jch)
文摘To develop a NaI （T1） detector for in situ radioactivity monitoring in the marine environment and enhance the confidence of the probability of the gamma-spectrum analysis, Monte Carlo simulations using the Monte Carlo N-Particle （ MNCP ） code were performed to provide the response spectra of some interested radionuclides and the background spectra originating from the natural radionuclides in seawater recorded by a NaI （T1） detector. A newly developed 75 mm × 75 mm NaI （T1） detector was calibrated using four reference radioactive sources 137Cs, 60Co, 40K and 54Mn in the laboratory before the field measurements in seawater. A simulation model was established for the detector immersed in seawater. The simulated spectra were all broadened with Gaussian pulses to reflect the statistical fluctuations and electrical noise in the real measurement. The simulated spectra show that the single-energy photons into the detector are mostly scattering low-energy photons and the high background in the low energy region mainly originates from the Compton effect of the high energy y-rays of natural radionuclides in seawater. The simulated background spectrum was compared with the experimental one recorded in field measurement and they seem to be in good agreement. The simulation method and spectra can be used for the accurate analysis of the filed measurement results of low concentration radioactivity in seawater.
文摘In the last years, the production of optical fibers cables has made possible the development of a range of spectroscopic probes for in situ analysis performing beyond nondestructive tests, environmental monitoring, security investigation, application in radiotherapy for dose monitoring, verification and validation. In this work, a system using an optical fiber cable to electromagnetic signal transmission from a NaI（TI） radiation detector is presented. The innovative device takes advantage mainly of the optical fibers large passband, small signal attenuation and immunity to electromagnetic interference to application for radiation detection systems. The main aim was to simplify the detection system making it to reach areas where the conventional device cannot access due to its lack of mobility and external dimensions. Some tests with this innovative system are presented and the results stimulate the continuity of the researches.
基金Supported by National Natural Science Foundation of China (10605022,10875053)US Department of Energy (DE-AC05-84ER-40150) under which Jefferson Science Associates operates the Thomas Jefferson National Accelerator Facility
文摘A precision measurment of inclusive electron scattering cross sections is carried out at Jefferson Lab in the quasi-elastic region for 4 He, 12 C, 56 Fe and 208 Pb targets. The longitudinal （R L ） and transverse （R T ） response functions of the nucleon need to be extracted precisely in the momentum transfer range 0.55 GeV/c≤ ｜ q ｜ ≤1.0 GeV/c. To achieve the above goal, a NaI （Tl） calorimeter is used to distinguish good electrons from background, including pions and low energy electrons rescattered from the walls of the spectrometer magnets. Due to a large set of kinematics and changes in HV settings, a number of calibrations are performed for the NaI （Tl） detector. Corrections for a few blocks of NaI （Tl） with bad or no signal are applied. The resolution of the NaI （Tl） detector after calibration reached δE/E^（1/2） ≈ 3% at E=1 GeV. The performance of the NaI （Tl） detector is compared with a simulation. The good calibration and background analysis for the NaI（Tl） detector are very important for the reduction of the systematic error of cross sections and the separation of R L and R T .
基金Supported by National Natural Science Foundation of China (10491303, 10775412, 10825524)Instrument Developing Project of Chinese Academy of Sciences (YZ200713)+1 种基金Major State Basic Research Development Program (2009CB825200, 2009CB825203,2009CB825206)Knowledge Innovation Project of Chinese Academy of Sciences (KJCX2-YW-N29)
文摘Understanding the radiation background at the north crossing point （NCP） in the tunnel of BEPCII is crucial for the performance safety of the High Purity Germanium （HPGe） detector, and in turn of great significance for long-term stable running of the energy measurement system. Therefore, as the first step, a NaI（T1） detector is constructed to continuously measure the radiation level of photons as background for future experiments. Furthermore, gamma and neutron dosimeters are utilized to explore the radiation distribution in the vicinity of the NCP where the HPGe detector will be located. Synthesizing all obtained information, the shielding for neutron irradiation is studied based on model-dependent theoretical analysis.
基金Supported by National Natural Science Foundation of China (10491303, 10775412, 10825524)Instrument Developing Projectof Chinese Academy of Sciences (YZ200713)+1 种基金Major State Basic Research Development Program (2009CB825206)KnowledgeInnovation Project of Chinese Academy of Sciences (KJCX2-YW-N29)
文摘The technique details for measuring radiation dose are expounded. The results of gamma and neutron radiation levels are presented and the corresponding radiation shielding is discussed based on the simplified estimation. In addition, the photon radiation level move as background for future experiments is measured by a NaI（T1） detector.
