Moments of charge distributions in the reaction92Mo+92Mo at 14.7 MeV/u

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.     

晕核6He（25 MeV/u）在9Be上的破裂反应

25 MeV/u 6He+9Be反应的实验中利用多个探测器望远镜对反应产物进行了测量, 对实验中各个角度测量到的4He进行观察, 将其中两个有高能峰成分的探测器划分成三部分, 得到不同角度4He的单举能谱和破裂产生4He的微分截面. Different products of 6He nuclei from 9Be target has been measured with a 6He beam at energy of 25 MeV/u. The energy spectra at different angles for 4He isotope were analyzed and the experiment differential cross sections for the direct breakup reaction were obtained.     

35MeV/u 40 Ar+197 Au反应中热核的碎裂密度

许多提取核反应过程中熵产生的方法只适用于高能核反应过程 ,而约化d的产额方法可以用于较低能量的重离子核反应中 .对于 3 5MeV/u40 Ar+ 197Au的核反应过程 ,利用这种方法所得的熵和约化带电粒子多重性提取的熵结果一致 .对于后角热核发射体系 ,实验提取的核温度为 ( 4.7± 1 .2 )MeV ,熵为S/A =2 .5± 0 .5,根据实验提取的熵和核温度可以确定其碎裂密度小于 0 .1 ρ0     

Fragmentation of 95 MeV/u 12C and 75 MeV/u 13C. Application to secondary-beam production

The fragmentation of 95 MeV/u ¹²C and 75 MeV/u ¹³C projectiles, interacting with natural targets of different elements (⁹Be, Cu and ¹⁹⁷Au for ¹²C, and ⁹Be, Ni, and ¹⁸¹Ta for ¹³C) and of various thicknesses has been investigated at GANIL, using the doubly achromatic magnetic spectrometer LISE. The projectile-like fragments transmitted at 0 have been analysed using a silicon -E telescope and the -time-of-flight method. The results obtained with the thinnest targets are discussed in the scope of radioactive nuclear beam production. The fragment momentum distributions can be fitted by Gaussian peaks associated with exponential tails towards low momentum values. The experimental production yields are compared with the results of the simulation code LISE. It appears that this code reproduces satisfactorily the yields of nuclei close to the stability line, but strongly overestimates the production of very neutron-deficient nuclei.Received: 17 September 2002, Revised: 25 July 2003, Published online: 18 December 2003PACS: 25.70.Mn Projectile and target fragmentation - 29.90. + r Other topics in elementary-particle and nuclear physics experimental methods and instrumentation     

25MeV/u 6He+9Be破裂反应的α碎片发射

测量了在25MeV/u 6 He轰击9Be靶的破裂反应产生的α碎片双微分截面及角分布,并在Serber模型的框架下计算了在破裂反应中衍射破裂与擦去过程的贡献,并对结果进行了讨论. 结果表明基于包含衍射破裂和擦去过程的Serber模型可以对6He的直接反应进行较好地描述,擦去过程的贡献远大于衍射破裂的贡献. 相对于6Li而言,6He较大的去2n微分截面源于它的弱束缚特性.     

Reactions between 12C and heavy target nuclei at 84 MeV/u

Using an experimental setup which allows the coincident investigation of the various projectile and target fragments the reactions between 84 MeV/u ¹²C projectiles and different targets were studied. Impact parameters have been deduced from the size and multiplicity of projectile fragments. Using a “minimum bias” triqqer relative cross sections have been determined for the different reaction channels. New results on the production of medium-heavy fragments are presented.     

Reaction mechanisms of 10 to 43 MeV/u heavy ions

Measurements of particle emission, linear momentum transfer and angular momentum transfer have been used to explore reaction mechanisms in the intermediate energy range where qualitatively different nuclear processes may be observable. The current status of our understanding of heavy ion reaction mechanisms with projectiles having velocities comparable to the velocity of sound and the Fermi velocity is summarized.     

Investigation of the Kr + Au system at 22 MeV/u

With laser-atomic-beam-spectroscopy the hyperfinestructure splitting constants A, B and the lifetimes τ of the Mn I levels 3d⁵4s4p z⁴p_3/2,5/2 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.     

12C(50MeV/u)+209Bi反应中线性动量耗散机制研究

本文介绍~(12)C(50MeV/u)+~(209)Bi核反应中线性动量转移LMT分布的实验测定及结果,利用BUU方程对该碰撞过程进行了动力学模拟计算,对理论计算所得LMT分布和实验分布进行了比较和讨论。 The experimental measurements and results of LMT distribution in ~(12)C(50MeV/u)+~(208)Bi reaction are reported. By using BUU equation for nucleus-nucleus collision process, the dynamicimitation calculation is made. The theoretical calculated LMT distribution is compared with theexperimental one and some discussion has been reviewed.     

Elasticp+12C scattering between 0.3 and 2 MeV

Absolute differential cross-sections ofp+¹²C elastic scattering have been measured at _cm=89.1°, 118.7°, 146.9° for bombarding energies between 0.3 and 2.0 MeV. Revised level parameters of the first three excited states in¹³N have been extracted with aR-matrix analysis. It is shown that the influence of the bound ground-state of¹³N has an appreciable effect on low-energy scattering. Recent predictions concerning Mott-Schwinger polarization are also discussed.     

Fragment correlations in the reaction 9.03 MeV/u238U+natU

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.     

Elasticp+12C scattering between 0.3 and 2 MeV

Absolute differential cross-sections ofp+¹²C elastic scattering have been measured atθ _cm=89.1°, 118.7°, 146.9° for bombarding energies between 0.3 and 2.0 MeV. Revised level parameters of the first three excited states in¹³N have been extracted with aR-matrix analysis. It is shown that the influence of the bound ground-state of¹³N has an appreciable effect on low-energy scattering. Recent predictions concerning Mott-Schwinger polarization are also discussed.     

25MeV/u40Ar+115In反应碎片和轻带电粒子能量关联

通过对     

晕核6He（25 MeV/u）的单、双中子转移截面测量

实验测量了25 MeV/u 的6He+9Be反应中的单、双中子转移微分截面. 利用反应耦合道模型初步分析了实验数据, 计算大体重现截面值. 转移反应对末态有相当的选择性, 并且双中子转移截面主要来自到基态的一步过程. 后角度截面的上升可能与连续态的耦合有关. Differential cross sections for quasi elastic scattering at forward angles and for 1n and 2n transfer reaction at backward angles induced by 6He at 25 MeV/u from 9Be target were measured. The experimental data were analyzed in the framework of the CRC model. The raise at backward angle of the 1n and 2n transfer cross section can not reproduced by the current calculation.     

Competition between the fusion-fission and deep-inelastic orbiting mechanisms in the35Cl +12C reaction

The binary decay properties of the⁴⁷V nucleus, produced in the³⁵Cl +¹²C reaction, have been investigated at the³⁵Cl bombarding energiesE _lab = 180 and 200 MeV by means of a kinematical coincidence technique. Binary reaction products show full energy equilibration and a characteristic 1/sin(θ _cm) angular distribution. The elemental distribution of the fully-damped products is asymmetric, similar to what has previously been observed in the decay of the⁵⁶Ni nucleus. Comparison with theoretical model predictions suggests the occurrence of a fusion-fission rather than orbiting process. Moreover the calculations performed using the Extended Hauser-Feshbach Method reproduce well the experimental fission yields. A general discussion of orbiting and fusionfission experimental data of light heavy-ion systems is presented in the framework of the calculated number of available open channels for these systems.     

密度分布形式对Glauber模型计算σR的影响

描述了利用Glauber模型计算反应截面的一种方法 .该方法对Glauber模型中输入的密度分布形式进行了修正 ,计算了丰质子同中子核素 (N =3 )的激发函数 .对于该同中子素链 ,采用修正的密度分布得到的激发函数与HO分布得到的激发函数相比 ,在大于 1 0 0MeV/u的能量区域 ,两者都与实验值符合得很好 ,而在中能区 (小于 1 0 0MeV/u) ,用修正的密度分布计算得到的激发函数与实验值之间的差距较HO分布明显减小 ,并保持对所有计算的核核芯密度基本相同 .     

Angular momentum transfer and partition in the deep-inelastic reaction 664 MeV 84Kr + natAg

In- and out-of-plane angular distributions have been measured for sequential α-decay from target-like fragments produced in fully relaxed heavy-ion collisions. At angles equal to or larger than the target-recoil direction, the α-particle energy spectra are evaporation-like and the in-plane angular distributions are consistent with isotropy in the rest frame of the target recoil. The out-of-plane distributions exhibit an anisotropy of approximately two. Fragment spins were extracted from these distributions as a function of mass asymmetry. These spins are in agreement with those obtained from a simultaneous γ-ray multiplicity measurement. Both the fragment kinetic energies and intrinsic spins are consistent with rigid rotation of an intermediate complex consisting of two substantially deformed spheroids in near proximity.     

Investigation of linear momentum transfer on the 35 MeV/u Ar+U system

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.