Range and stopping-power tables for heavy ions

https://www.cns.s.u-tokyo.ac.jp/~shimoura/research/nuc_data/pdf/11.pdf

Energy levels of light nuclei A = 11-12

▪ Abstract The experimental extraction of detailed barrier distributions has brought a significant advance in the study of the fusion of heavy nuclei, and indeed in the entire heavy-ion reaction process. A quantitative understanding of the entrance-channel effects induced by target and projectile structure has emerged, based on recent high-precision measurements of fusion excitation functions. These distributions show clearly whether the experimental data are good enough to give the information required. They are also the functions best suited to the theoretical interpretation of the reaction dynamics—often presenting an unambiguous “fingerprint” of the target and projectile structure. We are now at the stage where we can start to exploit the insights gained in order to understand properties of the compound nucleus created: its spin distribution and evaporation residues, perhaps its possible shapes, and, in the case of heavy systems, its subsequent fission.

Measuring barriers to fusion

The conceptual problems arising in the definition and measurement of temperature in non-equilibrium states are discussed in this paper in situations where the local-equilibrium hypothesis is no longer satisfactory. This is a necessary and urgent discussion because of the increasing interest in thermodynamic theories beyond local equilibrium, in computer simulations, in non-linear statistical mechanics, in new experiments, and in technological applications of nanoscale systems and material sciences. First, we briefly review the concept of temperature from the perspectives of equilibrium thermodynamics and statistical mechanics. Afterwards, we explore which of the equilibrium concepts may be extrapolated beyond local equilibrium and which of them should be modified, then we review several attempts to define temperature in non-equilibrium situations from macroscopic and microscopic bases. A wide review of proposals is offered on effective non-equilibrium temperatures and their application to ideal and real gases, electromagnetic radiation, nuclear collisions, granular systems, glasses, sheared fluids, amorphous semiconductors and turbulent fluids. The consistency between the different relativistic transformation laws for temperature is discussed in the new light gained from this perspective. A wide bibliography is provided in order to foster further research in this field.

/pdf/temperature-in-non-equilibrium-states-a-review-of-open-2vvmx2wgla.pdf

Temperature in non-equilibrium states: a review of open problems and current proposals

https://escholarship.org/content/qt1qw9b8ct/qt1qw9b8ct.pdf?t=p0juew

Systematics of complex fragment emission in niobium-induced reactions

Fusion barriers, empirical and theoretical: Evidence for dynamic deformation in subbarrier fusion

Fusion excitation functions for1H and4He have been compared to a one-dimensional, barrier-penetration model. In contrast to fusion for heavier nuclei this simple model is completely adequate, except for the statically deformed targed233U. Empirical barrier heights are obtained and compared to those from two theoretical nuclear potentials. These empirical barriers (from cold reactants) are used as input for calculating evaporation spectra that arise from hot nuclear emitters. The excess of observed low-energy1H and4He emission signals information content concerning distortions of the hot nuclei.

Empirical and theoretical fusion barriers for1H and4He: Connections to evaporation from hot nuclei

We have analyzed a large set of mean energies and angular anisotropies for evaporative4He emission to obtain barriers to evaporation,B. These exit channel barriers are often substantially smaller than the corresponding empirical s-wave fusion barriersE0. The differences (E0-B) are interpreted as indicators of the extent of distortion of the emitters. These distortions have in turn been characterized by the deformation parameter for a spheroid α20. ForZ=80 the dependence ofB or {α}20 on spin is somewhat suggestive of the superdeformed shapes predicted by the liquid drop model. ForZ>70 significant distortions are indicated for emitters of both large and small spin.

Evaporation barriers for4He indicate very extended forms for many emitting nuclei

The formation cross section for Na/sup 24/ and Mg/sup 28/ was measured in targets of Cu, Ag, Au, and U bombarded with protons and helium ions over the energy range 320 to 880 Mev. In addition, the kinetic energy of these products was measured by a thick-target. recoil-range technique at incident proton energies of 0.7 and 3.0 Bev and an incident helium ion energy of 0.88 Bev. In both sets of properties there was found a close similarity in the results from helium ion and proton bombardments. In the case of the proton bombardments the results were compared to the predictions of the conventional model of high-energy regions. i,e., a fast nucleonic cascade followed by a slower evaporation cascade. It was found that the conventional model cannot reproduce the results, which suggests that another reaction mechanism, fragmentation, is required. Possible views of a fragmentation mechanism are presented, and the implications of the experimental results for the nature of the fragmentation mechanism are explored. (auth)

/pdf/ejection-of-large-fragments-in-high-energy-nuclear-reactions-1ueac55qcf.pdf

Ejection of Large Fragments in High-Energy Nuclear Reactions

Ranges and range straggling of recoils from nuclear reactions induced by the ions C/sup 12/, N/sup 14/, O/sup 16/, O/sup 18/ a nd Ne/sup 22/ with kinetic energies of 10 Mev per nucleon and less are reported. Range-energy curves were obtained for Tb/sup 149/ (recoil energies of 4 to 29 Mev) in Al, for At and Po (4 to 15 Mev) in Al, and for At and Po (4 to 9 Mev) in Au. Ranges of Tb/sup 149/ at the threshold of each reaction were obtained by extrapolation. The agreement of these and the directly measured values support the assumption of compoundnucleus formation used in calculating the recoil energies. The smaller recoil velocities in this study are of the same order as the Bohr velocity (2.2 x 10/sup 8/ cm/sec). The values of the average range and the straggling parameter are compared with stopping theory. The contribution to the measured range straggling from the nuclear reaction is discussed. These results and others were used to obtain values of the range for Xe/sup 139/ in Al from 0.1 to 70 Mev and for At/sup 203/ in Au from 0.01 to 10 Mev (auth)

John M. Alexander

Papers

Fusion barriers, empirical and theoretical: Evidence for dynamic deformation in subbarrier fusion

Empirical and theoretical fusion barriers for1H and4He: Connections to evaporation from hot nuclei

Evaporation barriers for4He indicate very extended forms for many emitting nuclei

Ejection of Large Fragments in High-Energy Nuclear Reactions

RANGES AND RANGE STRAGGLING OF Tb$sup 149$ At, AND Po