Programs in Physics & Physical Chemistry
|[Licence| Download | New Version Template] aahn_v1_0.gz(12 Kbytes)|
|Manuscript Title: POSDIF: a program to compute positron diffusion and annihilation in rare gases.|
|Authors: R.I. Campeanu|
|Program title: POSDIF|
|Catalogue identifier: AAHN_v1_0|
Distribution format: gz
|Journal reference: Comput. Phys. Commun. 25(1982)433|
|Programming language: Fortran.|
|RAM: 26K words|
|Word size: 32|
|Keywords: Atomic physics, Experiment, Positron, Diffusion equation, Lifetime spectrum, Crank-nicolson method, Finite differences, Momentum transfer, Effective charge.|
Nature of problem:
Calculates positron lifetime spectrum in a gas being given the gas pressure and temperature, the value of the external electric field strength and the fits to momentum dependence of the positron-atom momentum transfer cross section and of the effective charge number.
The parabolic equation, representing positron diffusion and annihilation in the gas, is solved using Crank-Nicholson method and other standard finite difference methods. At each timestep the velocity distribution is used to calculate the averaged effective charge number and the averaged positron momentum.
About 300 s CPU time on the IBM-360.
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