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.     

Approaching peripheral collisions in the reaction Ar+Au at 27.2 MeV/u by the associated neutron multiplicities

A 4π detector has been used to measure the neutron multiplicity associated with peripheral heavy ion reactions induced at 27.2 MeV/u. A strong correlation is observed between the number of emerging neutrons and the mass of the projectile-like-fragment. However, the large energy dissipation which is observed is still too small to support the idea of a pure massive transfer process.     

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.     

25MeV/u40Ar+115In反应碎片和轻带电粒子能量关联

通过对     

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.     

Population of Unstable Nuclides and Nuclear Temperature Extraction in 46.7MeV/u 12C Induced Reaction

The experiment results of unstable nucliaes decay by using the light charged particle correlation function obtained in ¹²C 46.7MeV/u+⁵⁸Ni experiment are reported.Under the assumption of statistical equilibrium,the nuclear temperatures are extracted,and the influence of the reaction mechanism on the nuclear temperature are also investigated.     

Peripheral collisions in the 84Kr + 92,98Mo,natAg and 197Au reactions at 22 MeV/u

Peripheral reactions induced on ⁹²Mo,⁹⁸Mo, ^natAg and ¹⁹⁷Au targets by 22 MeV per nucleon krypton beam were studied. Fragments observed with velocities close to the beam velocity can be interpreted as coming from a quasi-fragmentation of the projectile. The isotopic distributions measured for the fragments produced with the Kr projectile reflect some influence of the composite system. Thus it seems that projectile fragmentation is not the only mechanism involved in these reactions and that the mean field interaction still plays an important role at this energy.     

35MeV/u 40Ar+197Au反应中热核的统计发射研究

利用硅半导体+CsI(T1)闪烁体望远镜测量35MeV/u ⁴⁰Ar+¹⁹⁷Au中发射的轻带电粒子,用能谱斜率方法和双同位素产额比方法提取了核温度参量.研究了热核发射过程中的统计发射规律.     

30 MeV/u 40Ar+natAg反应中类弹碎片发射的时–空演化

报道了30MeV/u ⁴⁰Ar+^natAg反应中中等质量碎片(IMF)发射时间(τ)随发射源空间大小的演化规律,并对类弹碎片的发射时空进行了讨论.结果表明,IMF的发射时标与中等质量碎片关联函数以及发射源的核物质密度(ρ)有关,而与发射源的质量数的关系不大.对于能量较高的类弹碎片来说,在较小的核物质密度下提取的发射时间也较小,因此,在正常核物质密度参数下提取出的发射时间值可作为碎片实际发射时间的上限值.中速碎片的发射时间随密度大小的变化非常缓慢,提取出的发射时间值即可作为实际的发射时间.     

35MeV/u36Ar+124Sn反应中类弹产物的同位素分布特性

测量了35MeV/u³⁶Ar+¹²⁴Sn反应中5.3°处类弹产物的同位素分布,观察到随着出射动能的增加,产物的平均中质比逐渐减小而接近弹核的平均中质比.同位旋相关的量子分子动力学计算表明,随着反应时间的增加,类弹产物的平均出射动能逐渐减小而平均N/Z值则逐渐增大.另外,碰撞参数也影响类弹产物的同位素组成:随着碰撞参数的减小,类弹产物的平均N/Z值减小.     

35MeV/u 40Ar+197Au反应中复合核的激发能与温度

利用大面积位置灵敏气体探测器对35MeV/u ⁴⁰Ar+¹⁹⁷Au反应中形成的裂片进行了符合测量,由此得到了裂变复合核的速度分布.在大质量转移假设下扣除前平衡发射粒子的影响,得到复合核的激发能.另外利用望远镜探测器对反应中出射的轻带电粒子也进行了符合测量,并由后角α,p,d,t的能谱提取了复合核的温度.温度与激发能的关系没有表现出理论预言的相变特征.     

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.     

Energy Correlations between Fragments and Light Charged Particles in Reaction of 25MeV/u 40Ar+115In

The correlations between the emitted fragments at θ_lab=15°and the light charged particles(LCPs) at the close geometry configuration in the reaction of 25MeV/u ⁴⁰Ar+¹¹⁵In were measured. The energy correlations between fragments (4≤Zf≤14) and the LCPs including proton, deuterium, tritium and a particle as well as the energy spectra of the LCPs were obtained. The result shows the existence of sequential decay mechanism. It is found that the peak position of angular correlation is at the small angles and the most probable correlation angle is at 2°or so; The peak positions of the two components in the energy spectra of LCPs increase gradually with the mass of correlated partner; The lighter primaly products are more easier to be excited and decay to IMFs and the LCPs. In the Sequential decay, the yield of the LCPs with more heavier mass is higher than that of the lighter LCPs. The result reveals that the total correlation yield ratios summed over the fragments of Z_f=4—14 are 1: 1. 3: 1. 78: 7. 57 for proton, deuterium, tritium and a particles, respectively.     

30MeV/u 40Ar+115In反应中的IMF能谱

测量了30MeV/u ⁴⁰Ar束流轰击¹¹⁵In反应靶时出射的中等质量碎片(IMF)的能谱.通过比较在不同出射角度发射的同一种IMF的能谱,得到了IMF的发射机制随出射角的演化关系.在假定运动源速度和出射离子库仑位垒不随出射角变化的条件下,通过改变发射源的强度和核温度参量完成了对实验测得能谱的运动源拟合,并详细讨论了3个发射源所占份额和源强随出射角的演化关系.     

Origins of Intermediate Mass Fragments for 40Ar+natAg Reaction at 30 MeV/u

The energy spectra of intermediate-mass fragments (IMF) (3≤Z≤16) have been measured from 6° to 110° for ⁴⁰Ar+^natAg reachon at 30 MeV/u. The energy spectra were analyzed by the moving source model. The natUres of the projechle-like source, target-like source and mid-rapidity source as well as the evolution with angle and nuclear charge were discussed. Two intermediate mass fragments, measured by correlation method in forward angles, come from two sources. One comes from projectile-like source, and other one mainly comes from intermediate source respectively.     

形变对10.6MeV/u 84Kr+27Al反应裂变前粒子发射的影响

研究了形变效应对10.6MeV/u ⁸⁴Kr+²⁷Al反应中断前粒子发射的影响.发现通过测量的裂变前粒子多重性提取的裂变延迟时间将因此从20×10^－21s减少到5×10^－21s,表明增强的断前粒子发射有一部分来自形变效应的贡献.