Contents :
Prefragment Excitation energy Selection of Abrasion-Ablation model to calculate cross sections Plotting Abrasion-Ablation cross sections Mass model choice
Minimization
Geometrical LISE [Wil87] J.W.Wilson, L.W.Towsend, F.F.Badavi, NIM B18 (1987) 225-231. Currently the code contains four methods to calculate a prefragment excitation energy (See the dialog below).
Fig. The Prefragment excitation energy dialog (Click to zoom). Fig. The Prefragment excitation energy plots (Click to zoom).
The Ablation step is based on the fusion-evaporation model LisFus
[Tar03] for fast analytical calculations of fusion residues cross
sections, where the evaporation stage is treated in a macroscopic way on
the basis of a master equation which leads to diffusion equations as
proposed by Campi and Hűfner [Cam81], and reexamined lately by Gaimard
and Schmidt [Gai91]. Level densities and decay widths are taken from
the statistical analysis of Iljinov et al. [Ilj92]. The LISE evaporation
model works with probability distributions as function of excitation
energy taking into account initially eight possible parent and daughter
channels (n, 2n, p, 2p, d, t, [Gai91] J.-J.Gaimard, K.-H.Schmidt, Nucl.Phys. A531 (1991) 709-745. [Ilj92] A.S. Iljinov et al., Nucl. Phys. A543 (1992) 517. [Tar03] O.B. Tarasov, D. Bazin, NIM B 204 (2003) 174-178. [Tar08f] O.B. Tarasov, A.C.C.Villari, NIM B 266 (2008) 4670-4673.
Fig. Prefragment Search & Evaporation options dialog (Click to zoom). Fig. De-excitation channels plot (Click to zoom).
The "Evaporation calculator" is available in the Calculations menu or via the icon in the toolbar. The "Evaporation Calculator" dialog in action shown in Fig.4.1 allows to calculate and plot production cross-sections of different nuclei as a result of deexcitation of an excited nucleus (see Fig.4.2), and visulaize the evolution of excitation functions (Fig.4.3) using plots of input and output excitation energy distributions for a given nucleus: - Input parent distributions
- Nucleus de-excitation channels
- Emitted particles spectra
- Output daughter distributions
Fig.4.1. The Evapoaration dialog in action (Click to zoom). Fig.4.2. Two-dimensional plot of calculated cross-sections. The data is represented by rectangles centered at N (neutrons) and Z (protons), where the cross-section value depends on color and size of the rectangle. The user can change the display modes of rectangles, and also change the scale (Click to zoom). Fig.4.3. Excitation functions of ^{40}Ca produced in reaction of the ^{48}Ca beam with a Be-target. (Click to zoom).06/02/2001 v.4.18 Evaporation Calculator
Before plotting cross-sections with preliminary it is necessary to check the "Show Abasion-Ablation in X-section plots" box in the Preference dialog:
(Matrix method)
Fig. Dialog of User cross-section analysis using Abrasion-Ablation model (Matrix method)Fig. Final plot combined on four plots (Local-chi2, Local-LoD, Global-chi2, Global-LoD) based on user weights. Abrasion-Ablation minimization to describe user cross-sections
The new minimization utility recently developed in the LISE code
allows to deduce Abrasion-Ablation model parameters from comparison of
AA-calculation results with experimental cross-sections with selection
one from 28 mass models distributed with the LISE [LevMar] M.I.A. Lourakis, levmar: Levenbergâ€“Marquardt nonlinear least squares algorithms in C/C++, http://www.ics.forth.gr/lourakis/levmar/, 2004. Fig. Dialog of User cross-section analysis using Abrasion-Ablation model (Minimization method) (Click to zoom).Fig. Plot of logarithm ratios of Abrasion-Ablation calculations and experimental values. Fig. Plot of chi-square values.
06/02/2001 v.4.18
**Three step Abrasion-Ablation model****Monte Carlo method**
⋅ benchmarks of the "Distribtuion" method, ⋅ using more sophisticated event gates , ⋅ application of angular momentum |