60 A GeV16O原子核在核乳胶中的电磁离解

对60 A GeV¹⁶O在原子核乳胶中的电磁离解现象首次进行了高统计的研究,得到电磁离解截面随束流能量的增加而增加,射弹碎片电荷分布和200 A GeV¹⁶O在 乳胶中电磁离解的电荷分布一致,但电荷为3≤Z≤5的射弹碎片的发射概率低于200 A GeV能 区,这些特点和Weiszacker和Williams的经典电磁理论模型计算结果一致.60 A GeV¹⁶ O电磁离解下各反应道出现的概率和200 A GeV能区结果基本一致,但同14.6 关键词： 电磁离解 射弹碎片 碎裂     

Fragmentation of ^16O nuclei in nuclear emulsion

We present the topology of 16O fragmentation at 60A GeV in reactions with emulsion nuclei.We discuss the multiplicity distributions of projectile fragments.charged secondaries and their dependence on the target residues.     

60 A GeV16O原子核在核乳胶中的电磁离解

对60 A GeV16O在原子核乳胶中的电磁离解现象首次进行了高统计的研究,得到电磁离解截面随束流能量的增加而增加,射弹碎片电荷分布和200 A GeV16O在乳胶中电磁离解的电荷分布一致,但电荷为3≤Z≤5的射弹碎片的发射概率低于200 A GeV能区,这些特点和Weiszacker和Williams的经典电磁理论模型计算结果一致.60 A GeV16O电磁离解下各反应道出现的概率和200 A GeV能区结果基本一致,但同14.6 A GeV能区的结果不同,在60 A GeV能区16O电磁离解主要是由电偶及电四激发引起的巨偶极和巨四极共振及准氘核效应过程所致,这一点可以通过电磁离解下质子的多重数分布得到定性解释.电磁离解下α射弹碎片的分布同非弹核作用下α碎片的分布规律不同,说明α碎片的产生机制不同.     

Fragmentation in ^16 O-emulsion interactions at 3.7 A GeV

The topology of ¹⁶O fragmentation at 3.7 A GeV in reactions with emulsion nuclei is presented. The multiplicity distributions of projectile fragments,charged secondaries and their dependences on the projectile residues are discussed.     

3.7 A GeV 16O与乳胶作用相对论性α粒子的双源发射

对3.7 A GeV 16O与原子核乳胶作用α射弹碎片的发射进行了研究, 发现α射弹碎片的角分布不能用单一的旁观体-反应体模型来解释，所以假设α射弹碎片来源于两个温度不同的发射源。     

Production of helium projectile fragments in {16O－emulsion interactions at 4.5 A GeV/c

The measurements of partial production cross sections of the multiple helium projectile fragments emitted at 4.5 A GeV/c {}^{16}O－Em interactions are reported. We have studied the production rate of helium projectile fragments due to fragmentation of {}^{16}O ions and compared it with that obtained from different projectiles at various energies. The dependence of on the mass number of the incident beams is formulated. The multiplicity distributions of the helium fragments produced in {}^{16}O－Em interactions at different energies exhibit Koba－Nielson－Olesen (KNO) scaling. The correlation of helium projectile fragments and target fragments is also investigated and it is found that the average of target fragments is increased with the decrease of the number of helium fragments in peripheral interactions.     

Investigation of the mean free path of projectile fragments produced in 16O－Em collision at 60 A GeV

Results are presented for an investigation of the mean free path of projectile fragments with charge 3≤Z≤8, produced by 60 A GeV {}^{16}O in nuclear emulsion. No dependence of mean free path on the distance from the point of the fragment emission is observed and our result is consistent with the nonexistence of anomalons.     

60AGeV 16 O诱发乳胶核反应α射弹碎片发射研究

对60AGeV^16O诱发乳胶核反应射弹α碎片的发射进行了研究，得到α射弹碎片多重数分布服从KNO标度无关性。在边缘作用下，α射弹碎片的产生与靶核碎片的产生存在线性关联，靶核碎片平均多重数随α射弹碎片数的增加线性减小，它可以很好地利用核作用几何模型来解释。     

Intermittency in 3.7 A GeV ^16O-emulsion interactions

The intermittency effect has been studied for an interaction of 3.7 A GeV ^16O with emulsion using the distributions of both the pseudorapidity intervals and the azimuthal angle intervals of the shower particles emitted in a central rapidity region. The scaled factorial moments, reduced scaled factorial moments and multifractal moments as functions of the bin size in pseudorapidity and in azimuthal angle have been calculated and have revealed the presence of an intermittent behaviour which may be due to the random cascading property of the reaction. The anomalous fractal dimension has been found to increase with the increase of rank of the moment.     

INTERACTION MEAN FREE PATH OF He PROJECTILE FRAGMENTS FROM 16O-EM COLLISION AT 60 A GeV

The interaction mean free path of He projectile fragments, produced by the collisions of ^{16O at 60 A GeV in a nuclear emulsion, has been investigated. In the present analysis, 1555 He projectile fragments, giving rise to 320 secondary interactions, have been used. At a level of 3% a very weak signal of anomalons is observed, which comes mainly from the 3×He channel.}     

Phase-shift analysis of 16O + 16O elastic scattering

A phase-shift analysis has been carried out for ¹⁶O + ¹⁶O elastic scattering, resulting in unambiguous values for the reflection coefficients in the energy range of the first gross structure of the 90° excitation function, and answering some of the questions still open regarding the calculations existing so far.     

张量力在16O+16O熔合动力学中的效应（英文）

利用时间相关Hartree-Fock 理论和完整Skyrme 有效相互作用研究了16O+16O 碰撞在库仑位垒附近的熔合动力学。数值计算是在没有任何对称性约束的三维笛卡尔基下完成。将时间相关Hartree-Fock 理论和冻结密度近似下的能量密度泛函方法给出的库仑位垒与实验结果进行了比较,发现同位旋标量的张量项能降低自旋饱和体系16O+16O的库仑位垒,而库仑位垒高度随着同位旋矢量的张量项的耦合常数减小而降低。并计算了包含和不包含张量力的16O+16O熔合截面,发现张量力对16O+16O碰撞在库仑位垒附近的熔合动力学影响较小。The fusion dynamics of 16O+16O around Coulomb barrier has been studied in the timedependent Hartree-Fock (TDHF) theory with the full Skyrme effective interaction. The calculations have been carried out in three-dimensional Cartesian basis without any symmetry restrictions. We have included the full tensor force and all the time-odd terms in Skyrme energy density functional (EDF). The Coulomb barrier obtained from the dynamical TDHF calculations and EDF with frozen density approximation has been compared with the available experimental data. The isoscalar tensor terms and the rearrangement of other terms are found to decrease the barrier height in the spin-saturated system 16O+16O, while the energy of Coulomb barrier tends to decrease as the isovector coupling constant decreases. The fusion cross section for 16O+16O collision has been calculated with and without the tensor force. We found that the tensor force has minor effect on the fusion dynamics of 16O+16O at the energies around Coulomb barrier.     

Phase-shift analysis of 16O + 16O elastic scattering data

A phase-shift analysis of precisely measured elastic ¹⁶O + ¹⁶O data has been carried out in order to establish the existence of molecular resonances between E_c.m = 15.5 and 18 MeV and to investigate the possible structure of these resonances.     

Fusion cross section of the 16O + 16O collision

It is shown that the gross structure of the fusion cross section of the ¹⁶O + ¹⁶O collision is well reproduced by a simple coupled channel method including only elastic and inelastic ¹⁶O + ¹⁶O(3^?) channels, as well as the excitation functions of the elastic and total inelastic ¹⁶O + ¹⁶O(3^?) cross sections.     

The heavy-ion reaction channels of the system 16O + 16O

The reaction channels of the system ¹⁶O + ¹⁶O with outgoing heavy particles from lithium to magnesium have been measured using a ΔE-E telescope. Excitation functions from 49 to 65 MeV at θ_Lab = 30° and angular distributions from θ_Lab = 10° (20°) to 50° at E_Lab = 51.5 MeV are presented for the strong transitions. The excitation function of the ¹²C-²⁰Ne (4.25 MeV) channel shows a pronounced regular cross structure with peaks at 52 and 60 MeV. A selective excitation of certain states in the inelastic scattering and the ¹²C-²⁰Ne channel is observed; the yields of the other heavy-ion channels being weaker by at least one order of magnitude. An explanation of this phenomenon is given by considering the angular momentum matching between entrance and exit channels. Furthermore it is shown that no strong dependence of the cross sections on the transferred angular momentum or on the nuclear structure of the final states is observed. Possible implications of these results on the reaction mechanism are discussed.     

Low energy fusion of 12C + 12C and 16O + 16O systems

The adiabatic time-dependent Hartree-Fock method (ATDHF) is applied to the calculation of low energy fusion of ¹²C + ¹²C and ¹⁶O + ¹⁶O systems. The energy dependence of the results is in good agreement with experiment, while the order of magnitude is not correct. It is shown that the dynamical effects included in ATDHF are very important and cannot be neglected at the energies of astrophysical interest.     

Isotopic production cross sections of fragmentation residues produced by 18O ions on a carbon target near 260 MeV/nucleon

The isotopic cross sections of residual nuclei produced in fragmentation reactions of ¹⁸O projectiles impinging on a carbon target at energies near 260 MeV/nucleon were measured at the HIRFL facility in Lanzhou (China). A full identification of atomic and mass numbers of fragments was achieved from the determination of their magnetic rigidity, energy loss, and time of flight. The production cross sections for a dozen of nitrogen, carbon, and boron isotopes were determined with uncertainties below 30% for most of the cases. The obtained cross sections for N and B isotopes show a rather good agreement with previous experimental data obtained with different projectile energies. The cross sections for some C isotopes seem to exhibit a dependence on the projectile energy. A comparison of the data and several theoretical model calculations are presented.     

Absolute frequency measurements of 12C16O and 13C16O laser transitions

The absolute frequencies of one 5.2 μm ¹²C¹⁶O laser line and one 5.3 μm ¹³C¹⁶O laser line have been measured against 10 μm band transitions of the CO₂ laser by heterodyning in a tungsten-nickel diode. The frequencies, wavelengths and wave numbers of these lines are reported to an accuracy of one part in 10⁷.     

Alpha cluster states in 16O

A very successful cluster-core model for the rotational bands of light nuclei has been extended to treat excited core states. The resulting coupled-channels problem has been solved for the ${}^{16}\text{O }{}^{12}\text{C + α}$ system. As well as the known + ve and ? ve parity bands many new levels are predicted and compared with experiment. The agreement between theory and experiment is very good both for the excitation energies and the decay properties. We predict the positions of two low-spin non-natural parity levels with E_x < 20 MeV and the positions of many high-spin states. In particular, we explain why the 8⁺ level seen in α-transfer at 22.5 MeV could not be found in the α-scattering cross sections and predict a second 8⁺ at 24.4 MeV. We discuss how the levels may be regarded as members of rotational bands and determine the terminating J-values for these bands. Finally we show that the usual rotational model would be a poor approximation for the cluster bands of ¹⁶O.     

The reaction 14C(3He,n)16O and the coexistence model of 16O

The reaction ¹⁴C(³He, n)¹⁶O has been measured at a ³He bombarding energy of 25.4 MeV. The zero-degree differential cross section for the excitation of the three low lying 0⁺T = 0 states, at energies 0.0, 6.05 and 12.05 MeV are, respectively, 1.33 ± 0.10, 0.49 ± 0.10, and 0.50 ± 0.10 mb/sr These measured cross sections are in rough agreement with single-step zero-range DWBA calculations using an empirically determined ¹⁴C ground state wave function and in which the Brown and Green coexistence-model wave functions are used to describe the ¹⁶O 0⁺ states. The angular distribution of the transition to the ground state is measured between 0° and 32°.