LISE++

Tools for COSY and LISE⁺⁺ from Mauricio Portillo

• COSY to LISE⁺⁺ tools (zip)
• Convert LISE⁺⁺ Monte Carlo output to ROOT ntuple (C)
• COSY FOX editor tools (zip)
• COSY to MOCADI map conversion and command builder (zip)

Transport Integral: A method to calculate the time evolution
of phase-space distributions

D.Bazin and B.M.Sherrill, Physical Review E, vol.50 (5), 1994, pp.4017-4021.

An analytical technique using integral equations for the transport of ion-optical intensity distributions through magnetic systems is described. It can serve as an alternative to Monte Carlo simulation to calculate the time evolution of phase-space distributions of any given shape. Under the assumption of linear optics, the solution of the integral equations can be reduced to convolution  products. One major application of this approach is the fast calculation of the transmission and purification of radioactive nuclear beams produced by projectile fragmentation.

transport_integral.pdf

Application to fusion-evaporation: LisFus & PACE4

O.B.Tarasov, D.Bazin, NIM B204 (2003) 174-178

A new fusion-evaporation model, LisFus, for the fast calculation of fusion-residue cross sections has been developed within the framework of the LISE code. This model can calculate very small cross sections quickly compared with programs using the Monte Carlo method. This type of fast calculation is necessary to estimate fusion-residue yields. Using this model, the LISE program can now calculate the transmission of fusion residues through a fragment separator.

It is also possible to use fusion-residue cross sections calculated by the program PACE, which has been incorporated into the LISE package. The PACE code is a modified version of JULIAN, the Hillman-Eyal evaporation code, using a Monte Carlo treatment of angular momentum. A comparison between PACE and the LisFus model is presented.

NIM B204 (2003) 174-178
5_15/lise_5_15.html

Universal parameterization of momentum distribution of
projectile fragmentation products

Fragment momentum distributions measured in relativistic heavy-ion collisions are typically observed to be Gaussian-shaped. Within the framework of the well-known statistical model, a parabolic dependence of the width of the Gaussian momentum distributions is obtained, and the fragment velocity is equal to the projectile velocity. However, this model is unable to account for the following:

Different models, both theoretical and empirical parameterizations, have been developed to explain these phenomena. Each of these models has advantages and drawbacks depending on energy, projectile mass, and other parameters. The universal parameterization, which avoids the indicated drawbacks inherent in the statistical  model, has been developed and adapted in the LISE program.  

This momentum-distribution model is universal: it includes a  definition of the distribution width depending on beam energy and on prefragment excitation energy, an estimate of the most probable fragment velocity, and a low-energy exponential tail. An attempt to describe experimental distributions of fragmentation products was made using a convolution of Gaussian and exponential line shapes. 

NNC 2003, Moscow (pdf 1.6 MB)

2026, compilation (pdf 2.3 MB)

Nuclear Physics A734 (2004) 536-540 (pdf 0.3 MB)

Statistical model calculations in heavy ion reactions (PACE)

A.Gavron, Phys.Rev. C21 (1980) 230-236

Results of various fusion experiments with heavy ions are compared with predictions of model calculations (PACE). In some reactions there is evidence for nonstatistical effects based on significant discrepancies between the calculations and the experimental results. Alternative explanations of these discrepancies are considered.

pace2.pdf

Calculated Nuclide Production Yields in Relativistic Collisions of Fissile Nuclei

J.Benlliure, A.Grewe, M.de Jong, K.-H.Schmidt, S.Zhdanov
Nucl.Phys. A628, 458 (1998)

A model calculation is presented which predicts the complex nuclide distribution resulting from peripheral relativistic heavy-ion collisions involving fissile nuclei. The model is based on a modern version of the abrasion-ablation model which describes the formation of excited prefragments due to the nuclear collisions and their consecutive decay. The competition between the evaporation of different light particles and fission is computed with an evaporation code which takes dissipative effects and the emission of intermediate-mass fragments into account. The nuclide distribution resulting from fission processes is treated by a semi-empirical description which includes the excitation-energy dependent influence of nuclear shell effects and pairing correlations. The calculations of collisions between 238U and different reaction partners reveal that a huge number of isotopes of all elements up to uranium is produced. The complex nuclide distribution shows the characteristics of fragmentation, mass-asymmetric low-energy fission and mass-symmetric high-energy fission. The yields of the different components for different reaction partners are studied. Consequences for technical applications are discussed.

NPA98_fission.pdf

A Reexamination of the Abrasion-Ablation Model for
 the Description of the Nuclear Fragmentation Reaction

J.-J.Gaimard, K.-H.Schmidt, Nucl.Phys. A531, 709 (1991)

The nuclear fragmentation reaction is studied as an important production mechanism for secondary beams. The geometrical abrasion model and a macroscopic evaporation model which describe the two steps of the reaction are reexamined. Several improvements and modifications of these models are discussed and a new model description incorporating these elements is proposed. In particular, the excitation energy and the angular-momentum distribution of the prefragments, the formulation of evaporation as a diffusion process and the role of microscopic structure in the production cross section are considered. The new model description preserves the simplicity and the transparency of the original models. The predictions of the new model are compared with those of the original models and with experimental cross sections. While the original models showed several systematic discrepancies in comparison to measured cross sections, the new model is able to reproduce the whole body of experimental data with satisfactory agreement.

ABLA07 - towards a complete description of the decay channels of
  a nuclear system from spontaneous fission to multifragmentation

Aleksandra Kelić, M. Valentina Ricciardi and Karl-Heinz Schmidt

The physics and the technical algorithms of the statistical de-excitation code ABLA07 are documented. The new developments of ABLA07 have been guided by the empirical knowledge obtained in a recent experimental campaign on the nuclide distributions measured at GSI, Darmstadt. Besides distinct signatures of very asymmetric binary splits, lighter systems show clear features of multifragmentation, while heavy systems reveal the influence of dynamics and microscopic structure on the fission process. ABLA07 includes elaborate but efficient descriptions of all these processes, with one set of the model parameters fixed for all systems and all energies.

ABLA07.pdf

Modified Empirical Parametrization of Fragmentation Cross Section

K.Summerer, B.Blank, Phys.Rev. C61, 034607 (2000)

New experimental data obtained mainly at the GSI/FRS facility allow one to modify the empirical parametrization of fragmentation cross sections. It will be shown that minor modifications of the parameters lead to a much better reproduction of measured cross sections. The most significant changes refer to the description of fragmentation yields close to the projectile and of the memory effect of neutron-deficient projectiles.

epax.pdf