共查询到19条相似文献,搜索用时 140 毫秒
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近两年来,有三个原子核乳胶实验观察到高能原子核碎片的异常现象[1-3].其中一个是由两个小组合作利用Bevalac(伯克利加州大学高能重粒子加速器)进行的.加拿大国家实验室的小组是用每核子2.1GeV的16O照射乳胶,加州大学小组是用每核子1.88GeV的56Fe照射乳胶.他们对于入射粒子和乳胶中原子核作用所产生的碎片的1460个次级作用进行分析,发现6%的碎片在乳胶中的平均自由程大约只有2.5cm,和同样电荷的正常原子核相比要小一个数量级.可是从这一长度来估计这种碎片的寿命,至少也应是10-11s.小的平均自由程表明截面异常大,如果这是由于原子核碎片… 相似文献
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大约四十年前,梅耶和詹森分别独立地提出了原子核壳模型,成功地解释了幻数等原子核结构的主要特性.虽然这个模型并未最终解决原子核结构问题,但它应作为研究原子核结构的基础模式已为世人所公认.因此,梅耶、詹森和对群论在核谱学上的应用作出重大贡献的魏格纳一起荣获了1963年度诺贝尔物理学奖金。本文介绍发现原子核壳模型的前后经过.卢瑟福发现原子内有核存在在1906年卢瑟福发现α粒子散射现象以后,盖革和马斯顿做了大量α粒子散射的研究工作. 相似文献
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在核密度模型基础之上利用原子核密度经验公式得到的核密度和利用电磁半径平方平均值得到的核密度分别计算了轻子 核深度非弹性散射过程中的核效应函数RHe/D(x, Q2), RLi/D(x, Q2), RC/Li(x, Q2), RCa/Li(x, Q2), 发现利用由原子核密度经验公式得到的核密度计算核效应函数所得结果与NMC实验数据符合得较好, 并且优于用后者方法计算核效应函数的理论结果, 从而说明利用原子核密度经验公式研究核子结构函数核效应的合理性。 The nuclear effect functions in l A DIS process RHe/D(x, Q2), RLi/D(x, Q2), RC/Li(x, Q2) and RCa/Li(x, Q2) are calculated on the basis of the nuclear density model by using nuclear densities obtained from an empirical formula or the experimental values of the electromagnetic mean of radius square 〈r2〉, respectively.It is shown that the nuclear effect functions obtained from the empirical formula are in good agreement with the NMC experimental data, and better than the later ones.The empirical formula of the nuclear density can be used to study the nuclear effect of nucleon structure functions reasonably. 相似文献
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本文综述了近年来我们组利用电子散射结合相对论平均场模型对奇特核结构的研究.我们发展了相对论平均场框架下的磁电子散射方法,并用其研究一些中子晕及质子晕核的基态组态,例如,23O,17,29C和23Al.研究发现,原子核不同组态的弹性磁形状因子彼此差别很大.其次,我们发展了相对论平均场框架下的弹性库伦电子散射方法,并用该方法研究了奇特核的电荷分布.研究发现,丰质子核中扩展的电荷密度分布可以通过库伦电子散射来测量.这种方法还被进一步推广用于计算弹性宇称不守恒电子散射,研究了一些典型原子核的中子密度分布,例如,Ca同位素链,N=50同中子素链以及N=Z的双幻核.结果表明,宇称不守恒非对称度的振幅主要由质子和中子形状因子极小值之间的距离决定.这些结果为下一代电子-核对撞机上的电子散射实验提供了有用的参考. 相似文献
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F. Bradna 《Czechoslovak Journal of Physics》1968,18(2):251-265
The study contains the results obtained in the process of the preparation and study of the properties of nuclear emulsion of a new type made especially for fast neutron dosimetry.Synthetic hydrophilic polymers were used for the preparation of the emulsion and the sensitivity to fast neutrons — by the detection of recoil protons — was increased by enriching the emulsion with elementary hydrogen and by the use of additive recoil proton radiators.The dosimetric results obtained with this emulsion are compared with the results achieved by various authors with the gelatine emulsions used up to now. 相似文献
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柴油、乙醇和水三组元乳化液流变特性的研究 总被引:3,自引:0,他引:3
研究了柴油、乙醇和水三组元乳化液的流变特性。实验发现乳化液在本文的组分配比下近似为牛顿流体,而且乳化剂的种类、含量以及乳化液的组分等均对乳化液的流变特性具有显著的影响。对于组分相同的乳化液,乳化液的粘度随着乳化剂含量和粘度的增加而增加;当乳化剂的含量和粘度相同时,若乙醇和水之间的相对质量分数保持不变,减少乳化液中柴油的含量(柴油不少于50%),乳化液的粘度随之增加。但是,柴油、乙醇和水三组元乳化液的粘度要比柴油、甲醇和水三组元乳化液的粘度大2到3倍。 相似文献
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STUDY OF THE NUCLEAR PHENOMENA IN THE LOW ENERGY (60-360 keV) PROTON BEAM IMPLANTATION ON METALS 下载免费PDF全文
A series of studies on the nuclear interaction and its effects in solids during proton implantation were performed in the energy region between 60 and 360keV. Some charged particle products were observed in the implantation experiments on metal samples such as deuterated titanium, titanium alloy, titanium foil on molybdenum substrate, molybdenum and stainless steel, etc.. The energies of the charged particle products are about 3.9, 5.6 and 8.4MeV, respectively. These particles were identified as alpha particles with both detector telescope and absorption measurements. These three kinds of alpha products were found from different proton sub-barrier reactions. The exciting curve of this reaction increases exponentially with the growth of proton energy in the energy region from 90 to 330keV. The radiation damages induced by the nuclear products in the sample have been studied with scanning electron microscopy technique. The possible surface damages induced by them were observed evidently. The origin of the nuclear reactions and their effect on implantation are discussed. 相似文献
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用IQMD模型分析了由96Ru和96Zr构成的质量对称、同位旋不对称的一组中能核反应,寻求对对称势强度的敏感量和研究反应最终是否达到平衡的问题.研究表明中子-质子差快度分布在弹或靶快度区对对称势强度敏感,且越丰中子的核系统越敏感.中子-质子差快度分布还表明能量为400MeV/u时达到的平衡程度要比100MeV/u时的高.出射的核子、轻带电粒子和中等质量碎片的N/Z显示IMF的出射有记忆效应.随着入射能量由100MeV/u增加到400MeV/u,IMF的N/Z有明显下降,这是由于随入射能量增加使IMF中同位素的分布发生变化所致. 相似文献
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We sum up here the results obtained on a cellulose nitrate detector (LR 115). LR 115 was irradiated with ions from proton and oxygen ions in the energy range 1–10 MeV/amu. Each irradiated sample consisted of a stack of several detectors (about 20–30) each thick. So chemical damages were studied according to the energy lost in each detector. Broken bonds were identified and quantified using infrared spectroscopy. In the same time we develop the same approach as proposed by Katz R. for the nuclear emulsion response. This approach is based on the hit theory, where the hits are produced by the secondary electrons removed by the incoming ion. Using this approach, neglecting any differences in the initial electron energy spectra and in the temporal aspect of energy deposition, it is surprising to simulate, with the very same parameters, the chemical cross sections from protons and oxygen ions. 相似文献
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The phase equilibrium of nuclear matter is studied thermodynamicallylat zero temperature. The equation of state obtained from the Thomas-Fermi model of Seyler-Blanchard shows that there are two kinds of states of the nuclear matter: gas and liquid. pure neutron matter is always in a gas phase.For the nuclear matter with two semi-infinite half spaces in contact at a plane boundary,the phase equilibrium is studied in three cases.Our calculation gives the neutron drip point δND=0.305 and the proton drip point δPD=0.678.The phase equilibrium is possible between two nuclear matter systems up to δC~0.89 where the system becomes homogeneous. 相似文献
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提出了一种比较精确且又省时的质子穿透的解析算法,并给出了考虑核反应后50—250MeV质子在水中的能量沉积,与Monte-Carlo方法的结果进行了比较.结果表明:1)非弹性核反应对质子的能量沉积有明显的影响,特别是对较高能量的质子束入射情况;2)该方法计算效率比Monte Carlo方法高百倍以上.因此,本文方法解决了质子能量沉积计算中效率和精度之间的矛盾,有可能在质子束放射治疗中得到实际应用.
关键词:
质子能量沉积
核反应
截面 相似文献
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《Nuclear Physics B》1988,301(4):517-524
This paper reports measurements of the hadrons produced in the inelastic scattering of 150 GeV positive muons in nuclear emulsion. Multiplicity distributions of secondary particles are given and are compared with the results of pion and proton interactions in emulsion at different energies. We find similarities as well as differences between muon and hadron collisions with nuclei. 相似文献
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在Walecka模型的基础上,应用热动力学理论和Dirac-Bruckner-Hartree-Fock方法,研究了有限温度不同密度下核子相对论微观光学势及其相应的薛定谔等效势和平均自由程.计算结果表明,核子薛定谔等效势和平均自由程对核密度的依赖相当敏感,当核密度增大时对核密度的依赖变得更为敏感. 相似文献