A Monte Carlo C-code for calculating transmission efficiency of recoil separators and viewing residue trajectories☆
Introduction
In heavy ion-induced complete fusion reactions, residues formed via evaporation of light particles from the compound nuclei (CN), peak around 0° with respect to the beam direction. Therefore, those are submerged in the intense primary beam background and transfer reaction products. Recoil separators [1] select residues rejecting other abundant reaction products and transport those to the focal plane for clean and unambiguous identification. This task is accomplished by applying optimized electric and magnetic fields. In the operation of any recoil separator, one of the most important aspects is its transmission efficiency. This is an integral ingredient in the determination of absolute reaction cross section. Also, for proper planning and execution of an experiment in a recoil separator, one must estimate transmission efficiency for the proposed system beforehand.
In this paper we report a semimicroscopic Monte Carlo code, TERS, for calculating Transmission Efficiency of Recoil Separators. The code also generates residue trajectory plots in the dispersive and the non-dispersive planes. As an illustration, we have applied the code for transmission efficiency calculation of the Heavy Ion Reaction Analyzer (HIRA) [2] at IUAC. However, the code, with suitable modification, can be applied to any other recoil separator which uses electromagnetic fields for separation and identification of residues.
The paper is organized as follows. Section 2 describes briefly the model used in developing the code and the flow diagram. The code description is given in Section 3. A test run with typical input and output is presented in Section 4.
Section snippets
The model and the flow diagram for the computer code
The model used in developing the code is described in detail in Ref. [3]. Therefore, we present here only a few important formulae, necessary to understand the code. Flow diagram of the calculational procedure is given in Fig. 1. Transmission efficiency is calculated in two steps. First, for each residue six parameters are calculated viz. x, θ, y, ϕ, E, q, where x, θ and y, ϕ are displacement and divergence in the dispersive () and the non-dispersive () planes, respectively (z is the beam
The code
The code consists of four C program files and five input files. It produces seventeen output files. A list of files with brief description is presented below.
Test run
Here we show an example of transmission efficiency calculation for the complete fusion reaction 16O + 184W, studied in HIRA, at leading to the compound nucleus 200Pb∗ [12]. We consider 5 neutron evaporation in the exit channel and 105 events. Following are the input parameters (in file ters_pti.inp) for the program ters_pti.c for performing projectile–target interaction calculation.
Generated distributions of residue angle, energy and charge state for this system are shown in Fig. 2.
Acknowledgement
The author is thankful to E.T. Subramanium for useful programming tips.
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This paper and its associated computer program are available via the Computer Physics Communications homepage on ScienceDirect (http://www.sciencedirect.com/science/journal/00104655).