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An inversion decomposition test based on Monte Carlo response matrix on the γ-ray spectra from NaI(Tl) scintillation detector

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Nuclear Science and Techniques 2016年第4期27卷 181-192页

作者： jian-Feng He Qi-Fan Wu jian-ping cheng Fang Fang Yao-Zong Yang Jin-Hui Qu Department of Engineering Physics Tsinghua University Beijing 100084 China Fundamental Science on Radioactive Geology and Exploration Technology Laboratory East China University of Technology Nanchang Jiangxi 330013 China College of Information Sciences and Technology Chengdu University of Technology Chengdu 610059 China Jiujiang Power Supply Subsidiary Company of State Grid jiangxi Electronic Power Company Jiujiang 332000 China

The Na I(Tl) scintillation detector has a number of unique advantages, including wide use, high light yield,and its low price. It is difficult to obtain the decomposition of instrument response spectrum because of limitations associated with the Na I(Tl) scintillation detector's energy resolution. This paper, based on the physical process of c photons released from decay nuclides, generating an instrument response spectrum, uses the Monte Carlo method to simulate c photons with Na I(Tl) scintillation detector interaction. The Monte Carlo response matrix is established by different single energy γ-rays with detector effects. The Gold and the improved Boosted-Gold iterative algorithms have also been used in this paper to solve the response matrix parameters through decomposing tests,such as simulating a multi-characteristic energy c-ray spectrum and simulating synthesized overlapping peaks cray spectrum. An inversion decomposition of the c instrument response spectrum for measured samples(U series, Th series and U–Th mixed sources, among others)can be achieved under the response matrix. The decomposing spectrum can be better distinguished between the similar energy characteristic peaks, which improve the error levels of activity analysis caused by the overlapping peak with significant effects.

关键词：闪烁探测器矩阵分解蒙特卡洛 NaI γ射线反演光谱能量分辨率

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Evaluation of the passivation effect and the first-principles calculation on surface termination of germanium detector

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Nuclear Science and Techniques 2021年第9期32卷 40-51页

作者： Sha-Sha Lv Yuan-Yuan Liu Wei-You Tang Li He Xiu-Xia Li jian-ping cheng Key Laboratory of Beam Technology of Ministry of Education College of Nuclear Science and TechnologyBeijing Normal UniversityBeijing 100875China Department of Engineering Physics Tsinghua UniversityBeijing 100084China Joint Research Center Nuctech Company LimitedBeijing 100084China

The point-contact high-purity germanium detector(HPGe)has the advantages of low background,low energy threshold,and high energy resolution and can be applied in the detection of rare-event ***,the performance of HPGe must be further improved to achieve superior energy resolution,low noise,and long-term *** this study,we combine computational simulations and experimental comparisons to deeply understand the passivation mechanism of *** surface passivation effect is calculated and inferred from the band structure and density of interface states,and further con-firmed by the minority carrier *** first-principles method based on the density functional theory was adopted to systematically study the lattice structure,band structure,and density of state(DOS)of four different systems:Ge–H,Ge–Ge-NH 2,Ge-OH,and Ge-SiO_(x).The electronic char-acteristics of the Ge(100)unit cell with different passi-vation groups and Si/O atomic ratios were *** shows that H,N,and O atoms can effectively reduce the surface DOS of the Ge *** passivation effect of the SiO_(x) group varied with increasing O atoms and Si/O atomic ***,SiO and SiO_(2) passivation films were fabricated by electron beam evaporation on a Ge substrate,and the valence state of Si and resistivity was measured to characterize the *** minority carrier lifetime of Ge-SiO_(2) is 21.3 ls,which is approximately quadruple that of *** passivation effect and mechanism are discussed in terms of hopping conduction and surface defect *** study builds a relationship between the passivation effect and different termination groups,and provides technical support for the potential passivation layer,which can be applied in Ge detectors with ultralow energy thresholds and especially in HPGe for rare-event physics detection experiments in future.

关键词： Germanium detector Passivation Surface termination

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Experimental validation of material discrimination ability of muon scattering tomography at the TUMUTY facility

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Nuclear Science and Techniques 2019年第8期30卷 26-34页

作者： Xing-Yu Pan Yi-Fan Zheng Zhi Zeng Xue-Wu Wang jian-ping cheng Key Laboratory of Particle and Radiation Imaging(Ministry of Education) and Department of Engineering Physics Tsinghua UniversityBeijing 100084China Department of Nuclear Engineering University of CaliforniaBerkeleyCA 94709USA Department of Radiology and Biomedical Imaging University of CaliforniaSan FranciscoCA 94143USA College of Nuclear Science and Technology Beijing Normal UniversityBeijing 100875China

Muon scattering tomography is believed to be a promising technique for cargo container inspection, owing to the ability of natural muons to penetrate into dense materials and the absence of artificial radiation. In this work, the material discrimination ability of muon scattering tomography is evaluated based on experiments at the Tsinghua University cosmic ray muon tomography facility,with four materials: flour(as drugs substitute), aluminum,steel, and lead. The features of the different materials could be discriminated with cluster analysis and classifiers based on support vector machine. The overall discrimination precisions for these four materials could reach 70, 95, and 99% with 1-, 5-, and 10-min-long measurement,respectively.

关键词： Muon tomography Cargo containerinspection Material discrimination SVM classifier

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Experimental investigation on the radiation background inside body counters

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Nuclear Science and Techniques 2022年第2期33卷 66-78页

作者： Yu Wang Yuan-Yuan Liu Bin Wu Xiang-Peng Meng jian-ping cheng Ying Wang Li-Jiao Wang Yun-Shi Xiao Qin-jian Cao jian-Feng Zhang Fei Tuo Key Laboratory of Beam Technology of Ministry of Education College of Nuclear Science and TechnologyBeijing Normal UniversityBeijing 100875China Department of Nuclear Safety China Institute of Atomic EnergyBeijing 102413China Department of Health Physics China Institute for Radiation ProtectionTaiyuan 030006China National Institute for Radiological Protection Chinese Center for Disease Control and PreventionBeijing 100088China

In vivo measurement of radioactivity based on various body counters is arguably the leading measure used to determine the distribution and activity of radionuclides in human subjects,such as I-131 in the thyroid,Am-241 in the lungs,and Pb-210 in the *** the measurements,the radiation background is the key factor that determines the sensitivity of the ***,to facilitate in vivo measurements,a well-designed shielding room is required to create a low-background ***,because the compositions of the radiation background are quite complicated,the respective contributions from each source remain obscure,which places a considerable burden on seeking an optimized design of shielding rooms that strikes the optimum balance between the construction cost and background suppression *** this study,we conducted a systematic experimental investigation on the radiation background outside and inside four representative body counters with assorted designs using a variety of radiation detectors,including high-purity germanium detectors,CdZnTe detector,radon emanometer,and gamma-ray *** carefully controlling the experimental conditions and synergetic analysis of the measurement results,in conjunction with previous studies,we separated and determined the relative contributions induced by environmental radiation(4%),airborne radon and its daughters(2%),the normal radioactivity of human subjects arising from K-40(58%),cosmic rays(12%),and radioactivity in shielding materials and measuring instruments(24%).Furthermore,based on these results,we discuss practical guidelines to design a shielding room for body counters.

关键词： Body counter Radiation background Shielding room In vivo measurement

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Evaluation of cosmogenic activation of copper and germanium during production in Jinping Underground Laboratory

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Nuclear Science and Techniques 2020年第5期31卷 70-76页

作者： Wei-He Zeng Hao Ma Ming Zeng Zhi Zeng Qian Yue jian-ping cheng Jun-Li Li Department of Engineering Physics Tsinghua UniversityBeijing 100084China Key Laboratory of Particle and Radiation Imaging(Tsinghua University) Ministry of EducationBeijing 100084China College of Nuclear Science and Technology Beijing Normal UniversityBeijing 100875China

Intrinsic radiation of materials is one of the major backgrounds for many rare-event search ***,the production of pure materials in an underground laboratory is a promising approach for eliminating cosmogenic *** this paper,we demonstrate a procedure to evaluate the yields of cosmogenic radionuclides in copper and germanium in the second phase of the China Jinping Underground *** results show that for copper and germanium materials,the largest cosmogenic background comes from 3 H and57,58,60Co,and 3 H and 68Ge,respectively,which all have yields on the order of 10-7 kg-1 *** corresponding radioactivities after 90 days pf exposure underground are estimated to be lower than 10-6μBq kg-1.

关键词： Cosmic rays Cosmogenic radionuclides Underground laboratory Monte Carlo simulation

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Surface metallization of PTFE and PTFE composites by ion implantation for low-background electronic substrates in rare-event detection experiments

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Nuclear Science and Techniques 2022年第7期33卷 37-47页

作者： Shao-Jun Zhang Yuan-Yuan Liu Sha-Sha Lv jian-ping cheng Bin Liao Pan Pang Zhi Deng Li He College of Nuclear Science and Technology Beijing Normal UniversityJoint Laboratory of Jinping Ultra-low Radiation Background Measurement of Ministry of Ecology and Environment Beijing Normal UniversityKey Laboratory of Beam Technology of Ministry of EducationBeijing Normal UniversityBeijing100875China Beijing Radiation Center Beijing100875China Department of Engineering Physics Key Laboratory of Particle and Radiation Imaging of Ministry of EducationTsinghua UniversityBeijing100084China Joint Research Center Nuctech Company LimitedBeijing100084China

Polytetrafluoroethylene(PTFE)is a low-background polymer that is applied to several applications in rare-event detection and underground low-background ***-based electronic substrates are important for reducing the detection limit of high-purity germanium detectors and scintillator calorimeters,which are widely applied in dark matter and 0υββdetection *** traditional adhesive bonding method between PTFE and copper is not conducive to working in liquid nitrogen and extremely low-temperature *** avoid adhesive bonding,PTFE must be processed for surface metallization owing to the mismatch between the PTFE and copper conductive ***-background PTFE matrix composites(m-PTFE)were selected to improve the electrical and mechanical properties of PTFE by introducing SiO_(2)/TiO_(2) *** microstructures,surface elements,and electrical properties of PTFE and m-PTFE were characterized and analyzed following ion *** and m-PTFE surfaces were found to be broken,degraded,and cross-linked by ion implantation,resulting in C=C conjugated double bonds,increased surface energy,and increased surface ***,the surface roughness,bond strength,and conjugated double bonds of m-PTFE were significantly more intense than those of ***,the interface bonding theory between PTFE and the metal copper foil was analyzed using the direct metallization ***,the peel strength of the optimized electronic substrates was higher than that of the industrial standard at extremely low temperatures,while maintaining excellent electrical properties.

关键词： Surface modification Polytetrafluoroethylene Ion implantation Surface metallization Low temperature resistance

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Characterization of a broad-energy germanium detector for its use in CJPL

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Nuclear Science and Techniques 2017年第1期28卷 42-48页

作者： Zhi Zeng Yu-Hao Mi Ming Zeng Hao Ma Qian Yue jian-ping cheng Jun-Li Li Rui Qiu Hui Zhang Key Laboratory of Particle and Radiation Imaging (Ministry of Education) and Department of Engineering Physics Tsinghua University Beijing 100084 China

The broad-energy germanium(BEGe)detector,with the ability of background discrimination using pulse shape discrimination,is a competitive candidate for neutrinoless double beta decay(ovββ)*** this paper,we report our measurements of key parameters for detector modeling in a commercial p-type BEGe ***-like sources are used to investigate energy resolution and linearity of the detector.A cylindrical volume source is used for efficiency *** an assembled device for source positioning and a collimated ^(133)Ba source,the detector is scanned to check its active *** an^(241)Am point-like source,the dead layer thicknesses is measured at about 0.17 mm on the front and 1.18 mm on the *** detector characterization is of importance for BEGe detectors to be used in the ovββ experiments at China Jinping underground Laboratory(CJPL).

关键词： BEGe Characterization Dead layer 0mbb CJPL

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Apoptosis of human pancreatic cancer cells induced by Triptolide

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World Journal of Gastroenterology 2008年第10期14卷 1504-1509页

作者： Guo-Xiong Zhou Xiao-Ling Ding Jie-Fei Huang Hong Zhang Sheng-Bao Wu jian-ping cheng Qun Wei Department of Gastroenterology Affiliated Hospital of Nantong University Nantong 226001 Jiangsu Province China

AIM: To investigate apoptosis in human pancreatic cancer cells induced by Triptolide (TL), and the relationship between this apoptosis and expression of caspase-3' bcl-2 and bax. METHODS: Human pancreatic cancer cell line SW1990 was cultured in DMEM media for this study. MTT assay was used to determine the cell growth inhibitory rate in vitro. Flow cytometry and TUNEL assay were used to detect the apoptosis of human pancreatic cancer cells before and after TL treatment. RT-PCR was used to detect the expression of apoptosis-associated gene caspase-3' bcl-2 and bax. RESULTS: TL inhibited the growth of human pancreatic cancer cells in a dose-and time-dependent manner. TL induced human pancreatic cancer cells to undergo apoptosis with typically apoptotic characteristics. TUNEL assay showed that after the treatment of human pancreatic cancer cells with 40 ng/mL TL for 12 h and 24 h, the apoptotic rates of human pancreatic cancer cells increased significantly. RT-PCR demonstrated that caspase-3 and bax were significantly up-regulated in SW1990 cells treated with TL while bcl-2 mRNA was not. CONCLUSION: TL is able to induce the apoptosis in human pancreatic cancer cells. This apoptosis may be mediated by up-regulating the expression of apoptosis- associated caspase-3 and bax gene.

关键词： Triptolide Pancreatic cancer Apoptosis Bcl-2 Caspase-3 Bax

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MUC1-positive circulating tumor cells and MUC1 protein predict chemotherapeutic efficacy in the treatment of metastatic breast cancer

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Chinese Journal of Cancer 2011年第1期30卷 54-61页

作者： jian-ping cheng Ying Yan Xiang-Yi Wang Yuan-Li Lu Yan-Hua Yuan Jun Jia Jun Ren Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education) Peking University School of Oncology Department of Medical Oncology Beijing Cancer Hospital & Institute Beijing 100142 P. R. China.

Chemotherapy plays an important role in the treatment of metastatic breast cancer. It is important to monitor chemotherapeutic efficacy, to find a simple and efficient tool to guide treatment, and to predict the efficacy of treatment in a timely and accurate manner. This study aimed to detect mucin-1 (MUC1) - positive circulating tumor cells and MUC1 protein in the peripheral blood of patients with metastatic breast cancer and to investigate their relationship to chemotherapeutic efficacy. MUC1 mRNA was detected in the peripheral blood of 34 patients with newly diagnosed metastatic breast cancer by reverse transcription- polymerase chain reaction. The positive rates of MUC1 mRNA were 88.2% before chemotherapy and 70.6% after chemotherapy, without a significant difference (P = 0.564); MUC1 mRNA expression before chemotherapy had no correlation with treatment effectiveness (P = 0.281). The response rate of MUC1 mRNA -negative patients after first-cycle chemotherapy was significantly higher (P = 0.009) and the progression-free survival (PFS) was clearly longer than those of MUC1 mRNA-positive patients (P = 0.095). MUC1 protein in peripheral blood plasma was detected by an ELISA competitive inhibition assay. The patients with decreased MUC1 protein after chemotherapy had a significantly longer PFS than those with elevated MUC1 protein (P = 0.044). These results indicate that the outcomes of MUC1 mRNA - negative patients after chemotherapy are better than those of MUC1 mRNA-positive patients. In addition, patients with decreased expression of MUC1 protein have a better PFS.

关键词： MUC1 治疗效果肿瘤细胞阳性率乳腺癌转移性粘蛋白化疗

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Circulating Tumor Cells in Metastatic Breast Cancer:Monitoring Response to Chemotherapy and Predicting Progression-Free Survival

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Chinese Journal of Cancer Research 2010年第3期22卷 201-210页

作者： jian-ping cheng Ying Yan Xiang-yi Wang Yuan-li Lu Yan-hua Yuan Xiao-li Wang Jun Jia Jun Ren Key Laboratory of Carcinogenesis and Translational Research(Ministry of Education) Department of Medical OncologyPeking University School of OncologyBeijing Cancer Hospital&Institute Beijing 100142China

Objective:The purpose of this study is to explore RT-PCR method to set up the examination platform for detecting circulating tumor cells(CTC) in peripheral blood from metastatic breast cancer *** primary endpoint is to find out the correlation of existence of CTC with clinical responses and progression-free survival(PFS).Methods:The breast cancer cell line MCF-7 was serially diluted into the peripheral blood from 45 healthy donors to set up the sensitivity of RT-PCR *** expression of CK19 mRNA was amplified from both 49 patients and 45 healthy donors *** CK19 protein quantity from plasma was measured by competitive inhibition ELISA ***:The sensitivity of RT-PCR could reach 1/106?107 white blood cells with specificity of 95.6%.The objective response rate(ORR) of patients with CK19 mRNA-negative undertaken one cycle chemotherapy was significantly higher than those with positive(P0.0001).PFS among CK19 mRNA-negative patients was also increased,although there was no significance(P=0.098).The results of ELISA assay showed that CK19 protein was decreased significantly after one cycle chemotherapy,which gave rise to a little higher ORR(P=0.015) and increased PFS(P=0.016).Conclusion:Patients with unamplified CK19 mRNA after one cycle chemotherapy could achieve better radiographic evaluation and increased PFS,which was showed to be of consistency with the CK19 protein assay among the patients treated.

关键词： Breast cancer Circulating tumor cells CK19 RT-PCR ELISA

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