共查询到20条相似文献,搜索用时 109 毫秒
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分子离子碎裂过程中,动能释放(KER)是一个重要的物理参量,通过研究其分布特征,可以获取母体离子态布居、分子结构、以及解离机制等信息.本文以CO2+→C++O+两体碎裂过程为例,详细介绍了KER的重构过程.利用C+离子的二维动量分布、KER与离子出射角度的关系,校准了影响KER重构的实验参数:飞行时间、飞行时间谱仪电压、位置坐标.校准过程中,只有当碎片离子的二维动量分布呈圆形或者KER与离子出射角的分布呈直线时,影响KER重构的参数才符合校准标准. 相似文献
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利用反应显微成像谱仪开展了50-keV/u Ne8+离子与C3H4分子碰撞实验,研究了丙二烯(CH2CCH2)和丙炔(CH3CCH)两种同分异构分子形成C3H42+二价离子并解离产生H+C3H2+H的过程.实验获得了H+和C3H2+的动量,进而通过动量守恒得到第3个碎片的动量.通过分析3个碎片的动能及解离的动能释放鉴别出未被探测的碎片为中性H原子的事件.借助Dalitz图、Newton图以及碎片产物的角分布等分析了该通道的动力学机制.结果表明,次序解离是该解离通道的主要机制,在碎裂过程中二价母体离子先解离成H+和C3H3+,中间体的... 相似文献
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采用离子动量成像谱仪研究了能量为1.0 ke V的电子束碰撞条件下CF4分子的解离动力学.实验上,对解离离子的三维动量进行了成像测量,通过离子飞行时间关联谱识别了CF42+异构化生成F2+分子的两个通道:F2++CF2+与CF++F2++F,得到了两个通道的离子动能及动能释放分布.对于其中的三体解离通道,我们进一步采用Dalitz图与Newton图等三体动力学分析方法对解离碎片的动量关联进行了分析.该通道以两个带电离子的背对背出射为主,中性的F原子作为旁观者只得到极小的反冲动量. 相似文献
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测量了200A GeV 32S核与Cu作用产生的重碎片P,Si,Al和Mg的角分布,得出它们的横动量分布宽度σpt在130—270MeV/c的范围. 相似文献
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The emission of projectile fragments alpha has been studied in 84Kr interactions with nuclei of the nuclear emulsion detector composition at relativistic energy below 2 GeV per nucleon. The
angular distribution of projectile fragments alpha in terms of transverse momentum could not be explained by a straight and
clean-cut collision geometry hypothesis of Participant — Spectator (PS) Model. Therefore, it is assumed that projectile fragments
alpha were produced from two separate sources that belong to the projectile spectator region differing drastically in their
temperatures. It has been clearly observed that the emission of projectile fragments alpha are from two different sources.
The contribution of projectile fragments alpha from contact layer or hot source is a few percent of the total emission of
projectile fragments alphas. Most of the projectile fragments alphas are emitted from the cold source. 相似文献
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The properties oflight particles emitted by the 32S + 27Al reaction at 135and 190 MeV bombarding energies were studied by means of a coincidence spectrometer. The spectrometer consisted of two large-area ionization chambers which measured the energy, momentum, mass and nuclear charge of the heavy reaction products. By requiring the conservation of those quantities the energy, momentum, mass and charge deficits were determined which are representative of the unobserved light particles. The analysis of the momentum deficit in the event plane did not yield an indication for a fast, direct process of light-particle emission. The alternative analysis in the fragments rest system confirmed the statistical nature of the emission process. The out-of-plane angular correlations were used to determine the spins of the particle-emitting fragments. 相似文献
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G. I. Kosenko F. A. Ivanyuk V. V. Pashkevich D. V. Dinner 《Physics of Atomic Nuclei》2008,71(12):2052-2066
The two-step model of fusion-fission reactions that was proposed previously by the present authors is extended in such a way as to describe the multiplicity of light particles emitted from nuclearfission fragments. Calculations are performed for the reaction induced by 48Ca + 244Pu collisions. The mass distribution of fragments, their mass-energy distribution, and the total multiplicity of neutrons and gamma rays are obtained for E lab = 230, 238, 249, and 255 MeV. It is shown that the model reproduces qualitatively relevant experimental data. In order to attain quantitative agreement, it is necessary to take into account the angular momentum carried away by particles from the nucleus undergoing fission and various types of gamma rays emitted by the nucleus and its fission fragments. 相似文献
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M. Jandel J. Kliman L. Krupa M. Morháč J. H. Hamilton J. Kormicki A. V. Ramayya J. K. Hwang Y. X. Luo D. Fong P. Gore 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 M. A. Stoyer R. Donangelo J. D. Cole 《The European Physical Journal A - Hadrons and Nuclei》2005,24(3):373-378
For the first time, average angular momenta of the ternary fission fragments 100, 102Zr, 106Mo, 144, 146Ba and 138, 140, 142Xe from the α-accompanied fission of 252Cf were obtained from relative intensities of prompt γ-ray transitions with the use of the statistical model calculation. Average values of the angular momenta were compared with the corresponding values for the same fission fragments from the binary fission of 252Cf. Results indicate the presence of a decreasing trend in the average values of angular momenta induced in ternary fission fragments compared to the same binary fission fragments. On the average, the total angular momentum extracted for ternary fission fragments is ∼1.4 ℏ lower than in binary fission. Consequently, results indicate that the mechanism of the ternary α-particles emission may directly effect an induction of angular momenta of fission fragments, and possible scenarios of such mechanisms are discussed. Further, the dependence of the angular momenta of 106Mo and 140Xe on the number of emitted neutrons from correlated pairs of primary fragments was obtained also showing a decreasing dependence of average angular momenta with increasing number of emitted neutrons. Consequences are briefly discussed. 相似文献
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J.M. Laget 《Physics letters. [Part B]》1977,68(1):58-62
The high momentum tail of the momentum distribution of the nucleons, emitted in the γD→ppπ? reaction, is explained in terms of single pion nucleon rescattering. 相似文献
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F. Rami A. Fahli J. P. Coffin G. Guillaume B. Heusch F. Jundt P. Wagner P. Fintz S. Kox Y. Schutz M. C. Mermaz 《Zeitschrift für Physik A Hadrons and Nuclei》1987,327(2):207-216
The projectile-like fragments emitted in the40Ar +68Zn reaction performed at 14.6, 19.6, 27.6 and 35 MeV/nucleon are studied. Their energy spectra and angular distributions have been measured. Velocities, widths of the linear momentum distributions and cross sections have been deduced. The results are discussedi) in terms of transfer of a few nucleons and analysed with a diffractional model. They are consistent, for stripping reactions, with a direct transfer of nucleons and a target excitation yielding multiparticlemultihole configurations,ii) In terms of projectile fragmentation-like process with a modified abrasion model taking into account the energy separation of the participant nucleons. The projectile fragmentation-like process appears above 20 MeV/nucleon and strongly competes with transfer of nucleons at 35 MeV/nucleon. The evolution of the mechanisms with incident energy is discussed on the basis of the reduced widths of the linear momentum distributions and on those of velocities and cross sections. 相似文献
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M.F. Rivet B. Borderie S. Song D. Guerreau H. Oeschler R. Bimbot I. Forest J. Galin D. Gardes B. Gatty M. Lefort B. Tamain X. Tarrago 《Nuclear Physics A》1982,387(1):143-155
Linear momentum transfers have been determined for C induced reactions at intermediate energies (30 to 84 MeV/u). On heavy targets, the angular correlation distributions of fission fragments indicate a limitation of the transferred momentum at 2 GeV/c in this energy range. Charged-particles emitted in coincidence with a fission fragment provide information on the prefission stage. The angular distribution of low-energy protons emitted by the heavy residues from the C + Ni reaction shows the same limitation of the transferred momentum at 2 GeV/c. Comparison of the proton and α-spectra with the results from an intranuclear cascade code including sequential cooling down of the residual partners is also given. 相似文献
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LIU Guan-Hua ZHAN Wen-Long ZHU Yong-Tai GUO Zhong-Yan HU Xiao-Qing XI Hong-Fei ZHOU Jian-Qun YIN Shu-Zhi FENG En-Pu ZHAO You-Xiong WEI Zhi-Yong FAN En-Jie 《中国物理C(英文版)》1993,17(2):166-172
The projectile-like fragments emittd from 46.7MeV/u 12C induced reactions have been measured.The most probable energies of the PLFs due to the projectile fragmentation can be reproduced within the Abrasion picture.Their parallel momentum distribution widths are found to fulfill the Goldhaber relation and the extraced reduced parallel momentum distribution width σ0 is 80±10MeV/c,which is close to the value obtained in the relativistic energy region.Futhermore,the values of σ0 are the same for different reaction systems in our experiment. 相似文献
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Dipak Ghosh Jaya Roy Ranjan Sengupta Sharmila Sarkar 《Zeitschrift für Physik A Hadrons and Nuclei》1992,342(2):191-193
A comparison of transverse momentum (P T) distribution of the alpha particles emitted as projectile fragments from12C-emulsion interaction at 4.5 A GeV/c with double Maxwell-Boltzmann distribution yields two temperatures in the projectile fragmentation region, i.e., 10 MeV and 40 MeV with different reaction mechanisms, thereby giving rise to two classes of events. This work presents a detailed study of the multiplicity characteristics for pions and protons emitted in both forward and backward hemispheres in these two classes of events. The results show some interesting features in these two classes. 相似文献
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E. Kh. Bazarov V. V. Glagolev K. G. Gulamov S. L. Lutpullaev K. Olimov Kh. Sh. Khamidov A. A. Yuldashev B. S. Yuldashev 《Physics of Atomic Nuclei》2005,68(9):1548-1550
The momentum features of protons originating from 16Op collisions at a momentum of 3.25 GeV/c per nucleon are analyzed. It is shown that the degree of excitation of the fragmenting nucleus affects predominantly the shape of the momentum spectrum of protons emitted into the backward hemisphere in the rest frame of the projectile nucleus and partly the shape of the spectra of protons emitted into the forward hemisphere and formed via the mechanisms of Fermi breakup and evaporation. 相似文献