共查询到20条相似文献,搜索用时 31 毫秒
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以SiC二极管和中子转换材料6LiF为基础,研制了SiC基中子探测器,并用241Am源与临界装置分别研究了SiC基中子探测器的粒子响应、热中子响应。结果表明:SiC基中子探测器能够满足241Am源粒子的计数测量,但由于SiC二极管灵敏区薄,故不能用于5.48 MeV的粒子能谱测量;SiC基中子探测器对热中子响应良好,不同功率下,脉冲幅度谱中可清晰看到由6Li(n,)3H的反应产物粒子、3H粒子形成的双峰;脉冲幅度甄别法可将射线及电子学噪声甄别掉;在直接测量与符合测量中,SiC基中子探测器的计数率均与临界装置功率成线性关系,且直接测量的线性度比符合测量的线性度好,最好可达0.999 97。研究表明:降低肖特基接触金属的厚度、增加其外延层厚度、提高其外延层品质,可将SiC二极管用于带电粒子能谱测量。 相似文献
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A simple correlation based on the gross theory ofβ-decay is derived between the neutron emission probabilitiesP n of delayed neutron precursors, theirβ-decay energies and the neutron binding energies of the daughter nuclei. The correlation is shown to be valid for delayed neutron precursors among the fission products. TheP n-values of several expected but still unidentified neutron precursors are estimated together with their contributions to the delayed neutron groups in thermal-neutron induced fission of235U. Some aspects of theβ-strength function for transitions into highly excited states are discussed. 相似文献
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G. G. Bunatian 《Physics of Particles and Nuclei》2012,43(6):867-881
We treat generic physical features of the production of neutrons from the high atomic number materials irradiated by the electron beam provided by linear electron accelerator. The bremsstrahlung of incident electrons inducing the photo-nuclear reactions is considered. The experimental data on photo-nuclear reactions are utilized to describe neutrons generating caused by the ??-radiation absorption. The generally received theoretical approaches are applied to explore the photo-neutrons energy distribution. The produced neutrons are primarily statistical, yet the direct neutrons share is noteworthy as well. The dependence of the neutron spectrum, mean neutron energy and total neutron yield on the energy and current of the electron beam and on the characteristics of irradiated samples is investigated. The analysis is plainly carried out in framework of the quantum electrodynamics and photo-nuclear physics, without having any recourse to the ??numerical Monte-Carlo simulations??. Our findings prove mainly to conform satisfactorily to the experimental measurements, so far as those are available for now. 相似文献
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A mechanism underlying the correlation between the reduced neutron and radiative widths for the chromium and nickel isotopes has been derived. This theory combines a channel together with a compound nucleus component. The bound-state single-particle reduced widths for 57Fe, 53Cr and 61Ni were obtained by fitting the cross-section and partial radiative width data from the (γ, n) experiments using R-matrix neutron scattering phase shifts. The thermal (n, γ) cross sections for 56Fe, 52Cr and 60Ni as well as the total radiative widths for resonances of several of these isotopes were obtained. The correlations between the neutron and total radiative widths are attributed to transitions to a few strong low-lying bound p-states which have large reduced widths. 相似文献
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C.-G. Källman 《Physics letters. [Part B]》1975,55(2):178-182
Quasi-classical field theory is used to predict abnormal behaviour of neutron matter in a model with neutrons, scalar mesons and vector mesons. We predict two stable families of neutron stars, a conventional one and an unconventional one with surface density in excess of 1015g cm?3, roughly. 相似文献
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V. I. Yurevich 《Physics of Particles and Nuclei》2012,43(3):367-418
We review progress made in the last quarter of a century in the field of neutron spectrometry over a wide energy range from ??1 MeV to a few tens of GeV. We consider spectrometers and detectors constructed in various laboratories for neutron measurements in numerous fundamental and applied studies. We discuss the results of works devoted to the development of experimental methods and the elaboration of new detectors. We pursue some promising avenues of further investigations. 相似文献
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D.J.C. Yates 《Physics letters. A》1979,72(6):479-480
Aspects of the surface physics and chemistry of neutron bottles are discussed in relation to the storage time anomaly. 相似文献
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The basic principle for the production of polarised thermal neutrons is discussed and the choice of various crystal monochromators
surveyed. Brief mention of broad-spectrum polarisers is made. The application of polarised neutrons to the study of magnetisation
density distributions in magnetic crystals, the dynamic concept of polarisation, principle and use of polarisation analysis,
the neutron spin-echo technique are discussed. 相似文献
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G. Belovitsky E. Konobeevski A. Stepanov V. Zavarzina S. Zuyev N. Polukhina N. Starkov S. Lukyanov Yu. Sobolev 《The European physical journal. Special topics》2007,150(1):5-7
To estimate the probability of two-neutron
configurations in halo nuclei, we propose an experimental method
of studying neutron-neutron correlations at periphery of such
nuclei by measuring two-neutron transfer reaction. The
experimental study of 6He + A ↦ 4He + B for various targets
is performed using 6He beam of Flerov Laboratory of Nuclear
Reactions (JINR, Dubna) at energy of about 15 MeV/u and technique
of nuclear photoemulsions. Searching for events of two-nucleon
transfer reaction and their processing is performed using the
PAVICOM-setup at P.N. Lebedev Physical Institute. 相似文献
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V. A. Andreev A. V. Vasiljev E. A. Ivanov D. S. Ilyin A. G. Krivshich A. P. Serebrov 《Technical Physics》2016,61(4):609-617
The gas-discharge detector is designed for the neutron lifetime spectrometer. The detector is intended for ultracold neutron flux monitoring in measurement cycles at the specrtometer (ILL, Grenoble, France). The detector has been successively tested with a Pu–Be neutron source under laboratory conditions and as a part of the spectrometer. 相似文献
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By means of X-γ andγ-γ coincidence measurements of the35Cl+58Ni reaction products, 38γ lines have been identified to be in coincidence with KX(Tc)-rays and assigned to the decay of90Ru. Its half-life of 11±3 s has been deduced from the 154.6 keVγ-decay. The result supports our previous identification of90Ru produced in the same reactions. 相似文献
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Scattering neutrons are one of the key factors that may affect the images of fast neutron radiog- raphy. In this paper, a mathematical model for scattered neutrons is developed on a cylinder sample, and an empirical formula for scattered neutrons is obtained. According to the results given by Monte Carlo methods, the parameters in the empirical formula are obtained with curve fitting, which confirms the logicality of the empirical formula. The curve-fitted parameters of common materials such as <'6>LiD are given. 相似文献
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A passive neutron area monitor has been designed using Monte Carlo methods; the monitor is a polyethylene cylinder with pairs of thermoluminescent dosimeters (TLD600 and TLD700) as thermal neutron detector. The monitor was calibrated with a bare and a thermalzed 241AmBe neutron sources and its performance was evaluated measuring the ambient dose equivalent due to photoneutrons produced by a 15 MV linear accelerator for radiotherapy and the neutrons in the output of a TRIGA Mark III radial beam port. 相似文献
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采用蒙特卡罗程序MCNP计算了西安脉冲堆中子代时间。使用MCNP程序模拟了反应堆瞬发中子通量密度衰减,基于忽略缓发中子项的点堆动力学方程计算出中子代时间。在微次临界下,研究了次临界度、源的分布、计数区域等对西安脉冲堆中子代时间计算结果的影响。计算分析表明:采用瞬发中子密度衰减法计算中子代时间时,微次临界度、源分布、计数区域等对计算结果影响都很小;误差产生的主要原因是忽略缓发中子项的点堆动力学方程并不能较好地反应瞬发中子通量密度的衰减规律。 相似文献