共查询到20条相似文献,搜索用时 15 毫秒
1.
R. Haag G. Fiedler R. Ulbrich G. Breitbach P. A. Gottschalk 《Zeitschrift für Physik A Hadrons and Nuclei》1984,316(2):183-193
Kinematically almost complete correlation studies on heavy fragments in the reaction 9.03 MeV/u238U+natU were performed using metaphosphate-glass detectors in a 2π-geometry technique. Absolute data for the total reaction cross-section and the partial cross-sections for the three-, four-, and five-body reaction channels were measured. The tracks of correlated particles were measured and converted into masses and energies. The reaction mechanism of each individual event was studied in terms of the separation velocities of correlated fragment pairs. Sequential fission following inelastic collision is found to account for all analysed events with more than two heavy nuclei in the exit channel. The masses, scattering angles, and energies of the first reaction step were reconstructed event by event. 相似文献
2.
S. Leray G. Nebbia C. Gregoire G. La Rana P. Lhenoret C. Mazur C. Ngô M. Ribrag E. Tomasi S. Chiodelli J.L. Charvet C. Lebrun 《Nuclear Physics A》1984,425(2):345-353
We have measured the angular correlation between two fragments emitted in the reactions Ar + Au and Ar + U at 44 MeV/u at GANIL. The aim was to investigate the amount of initial linear momentum transferred from the projectile to a fissioning nucleus. It turned out that this amount is much smaller than can be extrapolated from previous experiments. Furthermore, the probability of forming a fissioning nucleus is very small. 相似文献
3.
Morton Kaplan David J. Moses Dag Ø. Eriksen Mehmet Kildir Douglas R. G. Logan Michael S. Zisman Richard J. McDonald 《Zeitschrift für Physik A Hadrons and Nuclei》1983,313(1-2):31-37
Inclusive4He and4H energy spectra and heavy fragment coincidence correlations have been measured for reactions of 7.31 MeV/u238U with238U and?197Au targets. The H/He production cross sections are in the range 15–26 mb, and their emission spectra are very similar for the two systems. The observed strong kinematic shifts with angle are reproduced in shape and magnitude by Monte Carlo simulations of particle evaporation from projectile-like and target-like fragments, indicating competition between charged particle emission and sequential fission. No evidence is found for high energy charged particle emission associated with ultra-highZ composite systems. Heavy fragment measurements indicate an abundance of quasielastic and deeply inelastic reaction fragments, as well as sequential fission of target and projectile nuclei. For238U nuclei, the fission occurs predominantly in an asymmetric mode, reminiscent of fission at low excitation energy. For238+238U reactions in the vicinity of the grazing angle, the frequency of single sequential fission (with survival of the partner fragment) is twice as large as double sequential fission in which both the target and projectile undergo fission. In238U+197Au reactions, the survival probability of the heavy fragments is even greater. The surprisingly high survival probabilities of high-Z fragments imply a preponderance of very soft collisions in these very-heavy-ion reactions, at least at energies not very far over the Coulomb barrier. 相似文献
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M. D'Agostino M. Bruno F. Gramegna I. Iori P. F. Mastinu P. M. Milazzo E. Plagnol G. Vannini 《Zeitschrift für Physik A Hadrons and Nuclei》1995,353(2):191-196
Correlations between Intermediate Mass Fragments were measured for the reaction Xe + Cu atE/A= 45 MeV/u. The velocity correlation function for central 3-fold events, depleted at small values of the relative coordinate, as typical for fast decay processes, reflects the mutual Coulomb repulsion between the emitted fragments. From the comparisons between a significant number of experimental observables and the predictions of the Berlin Multifragmentation Model, it appears that the data are compatible with a simultaneous multifragment emission. 相似文献
7.
J. L. Charvet S. Joly M. Morjean Y. Patin Y. Pranal L. Sinopoli J. L. Uzureau R. Billerey B. Chambon A. Chbihi A. Chevarier N. Chevarier D. Drain C. Pastor M. Stern A. Péghaire 《Zeitschrift für Physik A Hadrons and Nuclei》1985,322(4):701-702
We have studied the heavy-ion capture reaction9Be(12C,γ)21 Ne at ECM=3.5–6.6 MeV and Θ = 90. High-energyγ-rav decay to the low-lying states of21Ne was observed, even well below the Coulomb barrier. 相似文献
8.
S. Hofmann D. Ackermann S. Antalic H. G. Burkhard V. F. Comas R. Dressler Z. Gan S. Heinz J. A. Heredia F. P. Heßberger J. Khuyagbaatar B. Kindler I. Kojouharov P. Kuusiniemi M. Leino B. Lommel R. Mann G. Münzenberg K. Nishio A. G. Popeko S. Saro H. J. Schött B. Streicher B. Sulignano J. Uusitalo M. Venhart A. V. Yeremin 《The European Physical Journal A - Hadrons and Nuclei》2007,32(3):251-260
The fusion reaction of 48Ca projectiles with 238U target nuclei was studied at the velocity filter SHIP of GSI in Darmstadt. Two decay chains were measured, which fully confirm
data that were previously assigned to the isotope 283112 in experiments at the Flerov Laboratory in Dubna. Two other events are consistent with a 50% spontaneous-fission (SF)
branch of this isotope. The mean value obtained for the half-life of 283112 is (6.9 +6.9
-2.3 s, the α energy is (9.520±0.015) MeV, and the total kinetic energy (TKE) of SF is (238±14) MeV. The half-life of the α decay
daughter nucleus 279Ds is (0.18 +0.32
-0.07 s, and the TKE of SF is (210 +32
-11 MeV. The cross-section deduced from all four events is (0.72 +0.58
-0.35 pb , measured at an excitation energy of 34.6MeV of the compound nucleus 286112. 相似文献
9.
I. E. Qureshi M. I. Shahzad S. Manzoor M. S. Zafar H. A. Khan 《Radiation measurements》1997,28(1-6):283-286
One of the main advantages of using dielectric track detectors in the study of heavy ion interactions is the possibility of observing each multi-prong event individually with complete kinematical details. It is thus possible to analyze even those reaction channels that have very low branching ratios. In the study of reactions induced by 16.7 MeV/u uranium ions incident on natural gold targets, we have observed 18 four-pronged events in a total detector area of 24 cm2. Using a polynomial range-energy relationship, empirically fitted to the observed data of binary and ternary events, it was possible to perform kinematical analysis of 10 out of 18 events. The masses and relative velocities of the reaction products, determined in this analysis were compared with theoretical prediction based on double sequential fission process. An agreement within one standard deviation with respect to theoretical values has been found for eight analysed events. 相似文献
10.
吕林辉 叶沿林 江栋兴 华辉 郑涛 李智焕 葛愉成 李湘庆 楼建玲 曹中鑫 宋玉收 肖军 李奇特 乔锐 游海波 陈瑞久 徐瑚珊 王建松 郭忠言 张雪荧 李琛 胡正国 陈若富 王猛 徐治国 岳珂 唐彬 臧永东 章学恒 姚向武 陈金达 白真 《中国物理 C》2011,35(10):891-895
A knockout reaction induced by 6He at 61.2 MeV/u was carried out at the HIRFL-RIBLL radioactive beam line. The α core fragments at forward angles were detected in coincidence with the recoiled protons at large angles. From this coincident measurement the valence nucleon knockout mechanism and the core knockout mechanism can be separated according to the polar angle correlation between the core fragments and the recoiled protons. It is demonstrated that, when reconstructing the resonant state of a weakly bound nucleus, the contamination resulting from the core knockout mechanism should be eliminated in order to obtain the correct structure information. 相似文献
11.
A. Charvet R. Béraud R. Duffait T. Ollivier M. Meyer R. Kossakowski S. André D. Barnéoud C. Foin J. Genevey A. Gizon J. Tréherne 《Zeitschrift für Physik A Hadrons and Nuclei》1985,320(4):605-607
The cross-sections of target-like residues following the14N+27Al reaction at 30 MeV/u have been measured from in-beam and radioactiveγ-ray spectra. The recoil velocities of some fragments have been estimated from theγ-ray Doppler broadening. 相似文献
12.
S. Gralla Dai Guang-xi A. Gobbi K. D. Hildenbrand W. F. J. Müller A. Olmi M. Petrovici H. Stelzer J. Tōke H. J. Wollersheim R. Bock U. Lynen 《Zeitschrift für Physik A Hadrons and Nuclei》1983,310(4):345-346
First and second moments of primary charge distributions were determined as a function of the total kinetic energy loss in the reaction92Mo+92Mo at an incident energy of 14.7 MeV/u. Up to energy losses of 200 MeV no significant drift of the first moments is observed. The second moments are in agreement with predictions of a stochastic model derived at lower bombarding energies. 相似文献
13.
R. Lucas J. Poitou J. V. Kratz G. Wirth 《Zeitschrift für Physik A Hadrons and Nuclei》1979,290(3):327-334
Angular distributions and integral cross sections for heavy reaction products from84Kr +238U collisions at 522 MeV were measured using catcher foil techniques and off-line X-ray identification of individual reaction product isotopes. There is no evidence for a fission-fusion mechanism being responsible for the formation of the “gold finger”. The data show that usual deep inelastic collisions account for the formation of all products with 70≦Z≦86. Compared to existing data atE≦605 MeV, the deduced mass distribution indicates reduced fission probabilities forZ≧80 fragments at 522 MeV. This is consistent with the expected dependence of fission probability on excitation energy and especially on angular momentum. 相似文献
14.
Yu.V. Pyatkov Yu.E. Penionzhkevich W.H. Trzaska O.I. Osetrov A.A. Alexandrov I.A. Alexandrova J. Äystö K.-Th. Brinkmann S.V. Khlebnikov V.F. Kushniruk A.V. Kuznetsov V.G. Lyapin V.A. Maslov M. Mutterer Z. Radivojevich V.A. Rubchenya Yu.G. Sobolev G.P. Tiourine D.N. Vakhtin 《The European Physical Journal A - Hadrons and Nuclei》2001,10(2):171-175
A pronounced fine structure (FS) in the form of distinct peaks was observed in neutron gated mass spectra from the decay of
the 278110 composite system produced in the reaction 238U + 40Ar (243 MeV) at an initial excitation energy E
* > 70 MeV. The FS peaks are located in the vicinity of mass numbers 70-80, 100, and 130, which correspond to those of magic
nuclei (clusters). In the data there is also evidence for a new type of decay -- collinear cluster tripartition of an excited
nucleus.
Received: 8 August 2000 / Accepted: 2 February 2001 相似文献
15.
D. Dalili M. Berlanger S. Leray R. Lucas C. Mazur C. Ngô M. Ribrag T. Suomijarvi C. Cerruti S. Chiodelli A. Demeyer D. Guinet A. Genoux Lubin C. Lebrun J. F. Lecolley F. Lefebvres M. Louvel 《Zeitschrift für Physik A Hadrons and Nuclei》1985,322(2):349-350
With laser-atomic-beam-spectroscopy the hyperfinestructure splitting constants A, B and the lifetimes τ of the Mn I levels 3d54s4p z4p3/2,5/2 were determined from the UV intercombination lines 321,7 nm and 322,5 nm. We obtained: A=?821(3)MHz, B=?40(30)MHz, τ=1120(50)nsec for the J=3/2 level and A=?607,8(1,5)MHz, B=+75(15)MHz, τ=970(50)nsec for the J=5/2 level. 相似文献
16.
《Nuclear Physics A》2006,764(1-2):34-51
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通过60MeV/u18O离子照射天然铀靶产生Ba放射性同位素,使用BaCl2沉淀法从大量铀和其它反应产物混合物中分离出Ba.通过离线γ谱学方法测量了Ba样品的γ射线单谱,根据Ba同位素特征γ射线峰的强度及其它相关数据计算了Ba同位素的生成截面.发现在厚铀靶的情况下,缺中子Ba同位素仍有较高的截面. The radioactive Ba isotopes were produced by 60 MeV/u~(18)O ion bombardment of natural uranium. Ba was separated from U and the reaction product mixture by BaCl_(2) precipitation. The Ba fraction was measured by off-line γ-ray spectroscopy. The cross sections of the individual Ba isotope were calculation based on the intensities of the character γ-ray peaks of Ba isotopes and other relative information. It was found that the n-deficient Ba isotopes have higher cross sections using the thick uranium targets. 相似文献
19.
Zeitschrift für Physik A Hadrons and nuclei - A measurement on the reaction U238(n,f) with 14 MeV neutrons has been done. The energies of the two fission fragments were analyzed in coincidence... 相似文献
20.
S. Leray O. Granier C. Ngô E. Tomasi C. Cerruti P. L'Henoret R. Lucas C. Mazur M. Ribrag J. L. Charvet C. Humeau J. P. Lochard M. Morjean Y. Patin L. Sinopoli J. Uzureau D. Guinet L. Vagneron A. Peghaire 《Zeitschrift für Physik A Hadrons and Nuclei》1985,321(3):533-534
All significant experimental results on the 3 H-3 He mass difference are reviewed. The weighted average of mass doublet measurements is 18596.7±3.6 eV, of tritium β measurements in magnetic spectrometers is 18610±7 eV and in implanted Si(Li) detectors is 18578±6 eV. The data within each group are consistent but there are discrepancies among the groups; possible explanations are proposed. Our best estimate for the 3 H-3 He atomic mass difference is 18599.4 ± 3.0 eV. 相似文献