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根据脉冲裂变中子测量对探测系统中子灵敏度的要求,改变了传统的中子靶室探测系统的设计模式,采取最优设计方案,设计了反冲法和裂变法结合的复合靶室装置,建立了两种测量靶室组合成为靶室主体长度仅为1.1m而且需要静态真空系统的中子复合靶室装置。测量靶室系统由“靶室主体、靶室支管、辐射体和PIN电流型探测器”组成,反冲法使用的辐射体是聚乙烯薄膜(CH2),裂变法使用的辐射体是^235U辐射体。 相似文献
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研制了一种新中子探测器,它以235UO2裂变靶作为转换靶,4He气体作为闪烁体.该探测器充分结合了235U和4He两种核素的特点,从而具有中子能量响应平坦、中子灵敏度较高、n/γ分辨本领高等优点,能很好地在混合脉冲裂变辐射场中测量中子.本文对探测器的原理和结构设计进行了介绍,计算了不同能量中子、γ射线在探测器中的能量沉积,并从理论和实验上对探测器的中子灵敏度、γ射线灵敏度、n/γ分辨本领和时间响应进行了研究.结果表明探测器的中子灵敏度约10-15C·cm2,γ灵敏度约10-17C·cm2,时间响应约33.1 ns. 相似文献
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具有统计增强效应的(CF2)n-PIN夹层探测阵列 总被引:1,自引:0,他引:1
采用灵敏区尺寸为φ60mm, 厚度1000μm的大面积电流型厚PIN半导体探测器+聚四氟乙烯片+PA101低噪声放大器, 构建了灵敏度为10-11C.cm2,具有显著统计增强效应的夹层高灵敏PIN探测阵列. 采用Monte-Carlo数值模拟方法, 研究了该探测阵列的统计增强效应和对γ射线探测灵敏度. 该阵列在极低强度脉冲γ射线探测中具有明显的统计增强效应, 且能量响应平坦, 单个阵列探测范围可达7个量级, 其γ灵敏度比直径为φ20mm, 厚度为250μm的单个PIN探测器高4个量级并可进行直接标定, 是低强度裂变n/γ混合场脉冲γ射线波形面积测量较理想的探测器, 已在有关科学实验中获得成功应用. 相似文献
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248 Cm和252Cf自发裂变瞬发中子谱测量 总被引:1,自引:0,他引:1
在飞行时间方法测量 2 0 0keV— 1 2MeV能区内2 48Cm和2 5 2 Cf自发裂变瞬发中子谱 ,以国际原子能机构推荐的2 5 2 Cf自发裂变瞬发中子谱为标准 ,可以免去探测器效率刻度的问题并消除系统误差 ,提高测量精度 .实验用一个微型电离室作为裂变碎片探测器 ,两个芪晶体中子探测器测量中子及一套基于微机的距离分别为 3 2 ,50和 1 0 0cm ,经过对数据的处理和分析给出了 2 0 0keV— 1 2MeV的中子能区内的实验数据 .用Maxwell分布对实验数据进行拟合 ,得到的核温度为 (1 4 0 1± 0 0 0 6)MeV . 相似文献
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M S Samant R P Anand R K Choudhury S S Kapoor K Kumar D M Nadkarni A Saxena 《Pramana》1993,40(4):299-309
The emission spectra of prompt fission neutrons from mass and kinetic energy selected fission fragments have been measured
in235U(n
th,f). Neutron energies were determined from the measurement of the neutron time of flight using a NE213 scintillation detector.
The fragment energies were measured by a pair of surface barrier detectors in one set of measurements and by a back-to-back
gridded ionization chamber in the second set of measurements. The data were analysed event by event to deduce neutron energy
in the rest frame of the emitting fragment for the determination of neutron emission spectra and multiplicities as a function
of the fragment mass and total kinetic energy. The results are compared with statistical model calculations using shell and
excitation energy dependent level density formulations to deduce the level density parameters of the neutron rich fragment
nuclei over a large range of fragment masses. 相似文献
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Abstract The effects of neutron, gamma and alpha radiations on the alpha and fission fragment tracks registration and revelation properties of CR-39 detectors (CR-39 and CR-39(DOP) were studied. It was found that the ratio of the bulk etch rate of irradiated to unirradiated (VG(irr.)/VG(unirr.) detectors is linearly dependent on dose. An exponential decrease in fission track densities with increase in neutron fluence was observed. The ratio of VG(irr.)/VG(unirr.) was found to be high in CR-39 than that in CR-39(DOP) exposed to the same reactor neutron fluence. The decrease in fission track densities with increase in neutron fluence was observed to be faster in CR-39 than in CR-39(DOP). This indicates that doping with dioctyl phthalate improves the radiation resistance of CR-39 detectors. It was observed that in detectors exposed to an alpha flux of the order of 9.36 × 106 / cm2, the fission track density was reduced by 11% and thereafter it remained constant. The results also indicate that thermal neutron fluence up to 7.01 ×1011 neutrons/cm2 does not affect the alpha and fission track densities. I.R. spectra were also studied to find out the nature of chemical changes produced by these radiations on CR-39. 相似文献
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P SUGATHAN A JHINGAN K S GOLDA T VARUGHESE S VENKATARAMANAN N SANEESH V V SATYANARAYANA S K SUMAN J ANTONY RUBY SHANTI K SINGH S K SAINI A GUPTA A KOTHARI P BARUA RAJESH KUMAR J ZACHARIAS R P SINGH B R BEHERA S K MANDAL I M GOVIL R K BHOWMIK 《Pramana》2014,83(5):807-815
The characteristics and performance of the newly commissioned neutron detector array at IUAC are described. The array consists of 100 BC501 liquid scintillators mounted in a semi-spherical geometry and are kept at a distance of 175 cm from the reaction point. Each detector is a 5″ × 5″ cylindrical cell coupled to 5″ diameter photomultiplier tube (PMT). Signal processing is realized using custom-designed home-made integrated electronic modules which perform neutron – gamma discrimination using zero cross timing and time-of-flight (TOF) technique. Compact custom built high voltage power supply developed using DC–DC converters are used to bias the detector. The neutrons are recorded in coincidence with fission fragments which are detected using multi-wire proportional counters mounted inside a 1 m diameter SS target chamber. The detectors and electronics have been tested off-line using radioactive sources and the results are presented. 相似文献
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S. A. Telezhnikov C. Granja J. Honzatko S. Pospisil I. Tomandl 《Physics of Particles and Nuclei Letters》2016,13(3):370-377
The neutron binding energy in 64Cu has been accurately measured in thermal neutron capture. A composite target of natural Cu and NaCl was used on a high flux neutron beam using a large measuring time. The γ-ray spectrum emitted in the (n, γ) reaction was measured with a HPGe detector in large statistics (up to 106 events per channel). Intrinsic limitations of HPGe detectors, which restrict the accuracy of energy calibration, were determined. The value B n of 64Cu was determined as 7915.867(24) keV. 相似文献
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N. I. Zamyatin A. E. Cheremukhin A. I. Shafronovskaya 《Physics of Particles and Nuclei Letters》2017,14(5):762-777
The results of measurements of 1-MeV (Si) equivalent fast neutron fluence with silicon planar detectors are reported. The measurement method is based on the linear dependence of the reverse detector current increment on the neutron fluence: ΔI = α I × Φ × V. This technique provides an opportunity to measure the equivalent fluence in a wide dynamic range from 108 to 1016 cm–2 with an unknown neutron energy spectrum and without detector calibration. The proposed method was used for monitoring in radiation resistance tests of different detector types at channel no. 3 of IBR-2 and for determining the fluence of fission and leakage neutrons at the KVINTA setup. 相似文献
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Fission-track registration characteristics of Lexan solid state nuclear track detectors have been used to measure the fast neutron induced fission cross section of232Th. The fast neutrons (?14.2MeV) were produced with the help of an AN-400 model Van-de-Graaff accelerator at Banaras Hindu University laboratory using3H(2H,n)4He reaction and were used to irradiate the fissile target deposited on the plastic detector. The track densityT, registered on the plastic detector is related to the fission cross sectionσ f, through the relationT=knσ føt wheren is the number of fissile atoms per cm2 in the deposit, ø is the neutron flux,k is fission track registration efficiency andt is the time of irradiation. The fission cross sectionσ f of232Th, relative to the well measured fission cross section of238U, was found to be 0.36±0.04 barn. 相似文献
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A. S. Koshelev L. Ye. Dovbysh M. A. Ovchinnikov G. N. Pikulina Yu. M. Drozdov S. V. Chuklyaev Yu. N. Pepyolyshev 《Physics of Atomic Nuclei》2017,80(8):1348-1356
The design of the fast neutron detector KNK-2-8M is outlined. The results of he detector study in the pulse counting mode with pulses from 238U nuclei fission in the radiator of the neutron-sensitive section and in the current mode with separation of functional section currents are presented. The possibilities of determination of the effective number of 238U nuclei in the radiator of the neutron-sensitive section are considered. The diagnostic capabilities of the detector in the counting mode are demonstrated, as exemplified by the analysis of reference data on characteristics of neutron fields in the BR-1 reactor hall. The diagnostic capabilities of the detector in the current mode are demonstrated, as exemplified by the results of measurements of 238U fission intensity in the power startup of the BR-K1 reactor in the fission pulse generation mode with delayed neutrons and the detector placed in the reactor cavity in conditions of large-scale variation of the reactor radiation fields. 相似文献
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Anita Topkar S. Praveenkumar Bharti Aggarwal S. K. Kataria M. D. Ghodgaonkar 《Pramana》2007,69(6):1085-1088
A specific research and development program has been carried out by BARC in India to develop the technology for large area
silicon strip detectors for application in nuclear and high energy physics experiments. These strip detectors will be used
as pre-shower detector in the CMS experiment at LHC, CERN for π
0/λ rejection. The fabrication technology to produce silicon strip detectors with very good uniformity over a large area of ∼40
cm2, low leakage currents of the order of 10 nA/cm2 per strip and high breakdown voltage of >500 V has been developed by BARC. The production of detectors is already under way
to deliver 1000 detector modules for the CMS and 90% production is completed. In this paper, research and development work
carried out to develop the detector fabrication technology is briefly described. The performance of the silicon strip detectors
produced in India is presented. The present status of the detector technology is discussed.
相似文献
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J. K. Hwang D. Fong A. V. Ramayya J. H. Hamilton M. Jandel C. J. Beyer J. Kormicki Y. X. Luo P. Gore J. Kliman L. Krupa M. Morhac G. M. Ter-Akopian Yu. Ts. Oganessian A. M. Rodin A. S. Fomichev G. S. Popeko A. V. Daniel J. O. Rasmussen A. O. Macchiavelli I. Y. Lee M. A. Stoyer R. Donangelo J. D. Cole 《Acta Physica Hungarica A》2003,18(2-4):383-391
He and Be ternary fission processes of 252Cf have been studied in two experiments with the Gammasphere detector array with light charged particle detectors surrounding the source. From α-γ double gated spectra, neutron multiplicity distributions were determined for related α ternary fission pairs. In going from binary to α ternary SF for approximately the same mass splittings (A ≈ 104–146) the average neutron multiplicity decreases about 0.7 AMU. In the first light charged particle (LCP) γ-γ experiment, the 10Be spectrum was cutoff below 27 MeV and in the recent experiment, below 18 MeV. For high energy (E > 27 MeV) 10Be ternary fission, the data indicate that the largest yields go via the cold process (zero neutron evaporation). In the recent experiment with E cutoff of 18 MeV, the 10Be ternary SF was observed for zero to 4n emissions. It seems that in some cases like 136Te, the On channel is the strongest and in the other cases like 100Zr the 1n or 2n channel dominates. Clearly, there is a shift to lower average number of neutrons emitted for 10Be compared to α ternary SF. The 104Zr and 136Te cases where zero neutron emission occurs may be related to the fact that these nuclei are near the limits of the more neutron rich Zr and Te nuclei observed. The 136Te is more spherical than the heavy partners in the other pairs and this may influence the 0n channel. Finally, the 0n channel may be more enhanced in the first data with the higher 10Be energy cutoff, leading to lower excitation energy. Also, we confirmed the 3368 keV peak with the FWHM of 60 keV emitted from the moving Be particles in the Doppler effect corrected spectrum. 相似文献
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A. I. Svirikhin V. N. Dushin M. L. Chelnokov V. I. Chepigin I. N. Izosimov D. E. Katrasev O. N. Malyshev A. Minkova A. G. Popeko E. A. Sokol A. V. Yeremin 《The European Physical Journal A - Hadrons and Nuclei》2010,44(3):393-396
The neutron-deficient isotope 246Fm , produced in the complete fusion reaction 40Ar$ + $208Pb , was investigated. The main goal of the experiment was to determine the neutron multiplicity at spontaneous fission of this isotope. For experiments aimed at the study of spontaneous fission of transfermium nuclei improvements in the focal plane detector system of recoil separator VASSILISSA have been made. A neutron detector consisting of 54 3He -filled counters has been mounted around the focal-plane detector chamber. From the experimental data the average number of neutrons per spontaneous fission of 246Fm was determined ( $ \bar{{\nu}}$ = 3.55±0.5) . 相似文献