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Manuscript Title: A Monte Carlo program to design a multiple module transition radiation detector.
Authors: M. Castellano, G. De Cataldo, N. Giglietto, E. Nappi, P. Spinelli
Program title: TRD_MULTI_SIM
Catalogue identifier: ABTD_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 61(1990)395
Programming language: Fortran.
Computer: VAX 6340.
Operating system: VMS VERSION 5.2.
RAM: 362K words
Word size: 32
Peripherals: disc.
Keywords: Particle physics, Elementary, Detector design, Transition radiation, Cluster counting.
Classification: 11.7.

Nature of problem:
We have developed a software package to design a transition radiation detector (TRD) to be used to discriminate fast charged particles from slower ones. Depending on the requirements and constraints from the experiment and on the performance expected for the detector, it is possible to simulate the behaviour of a TRD array of up to 64 modules. For each module (radiator and detector) the number and energy distribution of the X-rays together with background delta rays are calculated. The X-ray flow is then propagated through the downstream modules and the interposed materials, so that the relative contribution to each chamber is taken into account. Finally the program provides the global detected X-ray yield (number and energy distribution of photons) and background, issuing also a plot of the contamination fraction of the slow particles versus the efficiency in registering the fast ones.

Solution method:
Monte Carlo simulation.

The input design parameters should be chosen inside the limits eventually shown in the input list wherein the program has been tested and the assumptions for calculations are still adequate for a standard transition radiation based on a gas-filled proportional chamber. It is anyhow recommended to reply on literature orientative prescriptions on this subject in order to choose the starting parameters and to set-up properly the strategy of their optimization. A strict limitation to follow is that the mean energy of the single X- ray photon distribution must not exceed 50 KeV; a warning and the criterion to avoid this situation is issued when editing the input list.

Running time:
Depending on the kind of radiator selected, the typical VAX-6340 CPU time in seconds is about 8 times the number of TRD modules if they are identical. In this case if the radiators have an irregular structure the calculation takes only 30 seconds more than that for a regular radiator. If all modules are different, the elaboration takes 9 times the number of modules, for a regular radiator, or 40 times the number of modules, for an irregular one. These CPU times are evaluated for runs of 1000 events each.