The fragmentation of high-energy galactic heavy ions by nuclear interactions with arbitrary target nuclei is described within the context of a simple abrasion-ablation fragmentation model. The abrasion part of the theory utilizes a quantum-mechanical formalism based upon an optical model potential approximation to the exact ...
Energy Citations Database
The theory of galactic heavy ion fragmentation is furthered by incorporating a T matrix approach into the description of the three step process of abrasion, ablation, and final state interations. The connection between this T matrix and the interaction po...
National Technical Information Service (NTIS)
The fragmentation of target nuclei by relativistic protons and heavy ions is described within the context of a simple abrasion-ablation-final-state interaction model. Abrasion is described by a quantum mechanical formalism utilizing an optical model poten...
A systematic study of the population probabilities of nanosecond and microsecond isomers produced following the projectile fragmentation of 238 U at 750 MeV/nucleon has been undertaken at the SIS/FRS facility at GSI. Approximately 15 isomeric states in neutron-deficient nuclei around A�190 were identified and the corresponding isomeric ratios determined. The results are compared with a ...
NASA Astrophysics Data System (ADS)
The cross sections of the fragments produced in the projectile fragmentation reactions of the even calcium isotopes from A = 36 to A = 52 are calculated using the statistical abrasion ablation model. The neutron skin thickness are studied by investigating the fragments isotopic cross section distributions. The neutron-skin thicknesses ...
The theory of galactic heavy-ion fragmentation is furthered by incorporating a T-matrix approach into the description of the three-step process of abrasion, ablation, and final-state interations. The connection between this T matrix and the interaction potential is derived. For resonant states, the substitution of complex energies for ...
The high-charge-and energy (HZE) transport computer program HZETRN is developed to address the problems of free-space radiation transport and shielding. The HZETRN program is intended specifically for the design engineer who is interested in obtaining fast and accurate dosimetric information for the design and construction of space modules and devices. The program is based on a one-dimensional ...
The mechanism of particle evaporation was used to examine ablation effects in the fragmentation of 2.1 GeV/nucleon oxygen nuclei by lead targets. Following the initial abrasion process, the excited projectile prefragment is assumed to statistically decay in a manner analogous to that of a compound nucleus. The decay probabilities for the various particle emission channels are calculated by using ...
The cross sections of fragments produced of the six pairs of |T|=2 mirror nuclei projectile fragmentation were calculated using the statistical abrasion-ablation model. The isospin dependence of the projectile fragmentation are studied by investigating the fragments isotopic cross section distributions. It is found that the isospin dependence of the ...
A semiempirical abrasion-ablation model has been successful in generating a large nuclear database for the study of high charge and energy (HZE) ion beams, radiation physics, and galactic cosmic ray shielding. The cross sections that are generated are compared with measured HZE fragmentation data from various experimental groups. A research program for ...
Projectile fragmentation reactions have been investigated by the modified statistical abrasion-ablation model (SAA) and the heavy-ion phase-space exploration (HIPSE) model. From the fragment yield ratios, clear isoscaling behavior was observed in the calculated results of the two models. The extracted isoscaling ...
The abrasion-ablation model for reactions between relativistic heavy ions is derived from Glauber's multiple scattering theory. Simple expressions are found for the abrasion cross section and for the excitation energy of the projectile after abrasion. Both quantities depend on nuclear densities and on the nucleon-nucleon forward scattering amplitude. They ...
We study the relation between neutron removal cross section (sigma{sub -N}) and neutron skin thickness for finite neutron-rich nuclei using the statistical abrasion ablation model. Different sizes of neutron skin are obtained by adjusting the diffuseness parameter of neutrons in the Fermi distribution. It is demonstrated that there is ...
The 140 MeV/u 40,48Ca+9Be and 58,64Ni+9Be reactions are simulated by the statistical abrasion ablation model, and the simulation results are compared to the National Superconducting Cyclotron Laboratory (NSCL) experimental data. By comparing the fragment isotopic distributions of 40,48Ca and 58,64Ni, we study the isospin effect in the ...
In heavy ion reactions, neutron production at forward angles is observed to occur with a Gaussian shape that is centered near the beam energy and extends to energies well above that of the beam. This paper presents an abrasion-ablation model for making quantitative predictions of the neutron spectrum. To describe neutrons produced from the abrasion step of the reaction where ...
The fragmentation of target nuclei by relativistic protons and heavy ions is described within the context of a simple abrasion-ablation-final-state interaction model. Abrasion is described by a quantum mechanical formalism utilizing an optical model potential approximation. Nuclear charge distributions of the excited prefragments are ...
The semiempirical abrasion/ablation model has been successful in generating a large nuclear data base for use in the study of high charge and energy (HZE) ion beams, radiation physics and galactic cosmic ray shielding. The cross sections generated agree with the measured HZE fragmentation data to the degree that different experimental groups agree among ...
PubMed
Calculations of large mass fragment yields from high-energy heavy-ion reactions are performed based on the abrasion-ablation model. The geometrical picture of the cleancut fireball model is used to calculate the number of participant nucleons in the abrasion stage and the excitation energy of the spectators (primary residues). A standard statistical ...
Using a primary beam of 58Ni at 650 MeV/nucleon impinging on a beryllium target, production cross sections of proton-rich fragments from projectile fragmentation have been measured at the projectile-fragment separator FRS at Gesellschaft f�r Schwerionenforschung Darmstadt m.b.H. The experimental data ranging from nickel to scandium for isotopes close to stability as well as for fragments at the ...
Quantum mechanical optical model methods for calculating isotope production cross sections from the spallation of heavy nuclei by high-energy protons are developed from a modified abrasion-ablation collision formalism. The abrasion step is treated quantum-mechanically as a knockout process which leaves the residual prefragment nucleus in an excited state. ...
We have calculated the cross sections of the fragments produced in the projectile fragmentation of the even 36-52Ca isotopes using the statistical abrasion-ablation model. The isospin effect in the projectile fragmentation are studied by investigating the peak positions and the widths of the fragment isotopic cross section distributions. The peak positions ...
The neutron removal cross section [?-N(Z)] is defined for the projectile-like fragment isotopes and extended to the lower Z isotopes in the projectile fragmentation reaction. The cross sections of fragments in 1 A GeV even Ca42-52+C12 projectile fragmentation reactions are calculated using the statistical abrasion-ablation model. The correlations between ...
Seven previously unobserved neutron-rich isotopes (209Hg, 210Hg, 211Tl, 212Tl, 218Bi, 219Po and 220Po) have been identified among the fragmentation products of a 1000 MeV/nucleon 238U beam incident on a beryllium target. The ?-ray decays of 9 known and 4 new ?s-isomers in nuclei around 208Pb were also observed. Production cross sections and probabilities for populating isomeric states in the ...
An optical potential abrasion-ablation collision model is used to calculate hadronic dissociation cross sections for one, two, and three nucleon removal for the first time for a 14.6A GeV Si-28 beam fragmenting in aluminum, tin, and lead targets. These estimates are compared with recent semiinclusive measurements. Significant differences between some ...
The abrasion-ablation model is briefly described and then used to calculate cross sections for production of large fragments resulting from target or projectile fragmentation in high-energy heavy-ion collisions. The number of nucleons removed from the colliding nuclei in the abrasion stage and the excitation energy of the remaining fragments (primary products) are calculated ...
DOE Information Bridge
Codes used for space radiation shielding studies typically transport light-ions from the incident cosmic ray spectrum using either a one-dimensional straight-ahead approximation or in three dimensions, often without accounting for their breakup. Light-ions are also produced by breakup of energetic heavy ions in target materials. Herein, we present cross section models that can ...
Quantum mechanical optical potential methods for calculating inclusive isotope and element production cross sections from the fragmenting of heavy nuclei by intermediate- and high-energy protons and heavy ions are presented based upon a modified abrasion-ablation-FSI (frictional spectator interaction) collision model. The abrasion stage is treated as a ...
The large fragment yields are estimated for heavy (Z greater than 56) nuclei, using a simple theory based on a two-step abrasion/ablation model of Wilson et al. (1987), which includes a third-order correction for surface energy term. The results obtained for 1.047 GeV/n Au-197 nuclei, 1.128 GeV/n Ho-165 nuclei, 1.88 GeV/n Fe-56 nuclei, 1.239 GeV Xe-132 ...
The cross sections of the fragments that are produced by the 80 A MeV |Tz| = 2 mirror nuclei 20Mg/20O, 24Si/24Ni, 36Ca/36S, 40Ti/40Ar, 44Ca/44Cr and 60Ni/60Ge colliding on the 12C target are calculated using the statistical abrasion-ablation model. The isospin dependence of the projectile fragmentation (or the isospin effect) in the fragment cross section ...
... Accession Number : ADA205181. Title : Model Description for the SOCRATES Contamination Code. Descriptive Note : Final rept. ...
DTIC Science & Technology
... Accession Number : ADA113793. Title : A Description of the ARI Crew Performance Model. Descriptive Note : Final rept. ...
Description of a simplified Model Reference Adaptive Control (MRAC) Experiment that will be flown in
NASA Technical Reports Server (NTRS)
... ADA205109. Title : Description of the Derivation of the Collision Risk Model Used in the Vertical Separation Simulation Risk Model. ...
... Title : MODELS AND MODELLING FOR MANPOWER PLANNING. Descriptive Note : Management Sciences research rept.,. ...
... Title : DESCRIPTIVE CHARACTERISTICS AND ORDER STATISTICS INFERENCE FOR A MODEL WITH RELIABILITY FUNCTION S SUPER STAR ...
... Title : DESCRIPTION AND ANALYSIS OF THE DYNAMICS OF SERVOMECHANISMS WITH THE AID OF MATHEMATICAL MODELS,. ...
