Programs in Physics & Physical Chemistry
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|Manuscript Title: PIPIT: a momentum space optical potential code for pions. See erratum Comp. Phys. Commun. 13(1977)141.|
|Authors: R.A. Eisenstein, F. Tabakin|
|Program title: PIPIT|
|Catalogue identifier: ABIH_v1_0|
Distribution format: gz
|Journal reference: Comput. Phys. Commun. 12(1976)237|
|Programming language: Fortran.|
|Computer: UNIVAC 1108.|
|Operating system: UNIVAC EXEC II.|
|RAM: 35K words|
|Word size: 36|
|Keywords: Nuclear physics, Medium energy, Elastic scattering, Angular distribution, Cross section, Optical potential, Momentum space, Lippmann-schwinger, Pion.|
Nature of problem:
Angular distributions for the elastic scattering of pions are generated by summing a partial wave series. The elastic T-matrix elements for each partial wave are obtained by solving a relativistic Lippmann- Schwinger equation in momentum space using a matrix inversion technique. The Coulomb interaction is included essentially exactly using the method of Vincent and Phatak. The piN amplitude is obtained from phase shift information on-shell and incorporates a separable off-shell form factor to ensure a physically reasonable off-shell extrapolation. The piN interaction is of finite range and a kinematic transformation procedure is used to express the piN amplitude in the pi nucleus frame.
A maximum of 30 partial waves can be used in the present version of the program to calculate the cross section. The Lippman-Schwinger equation is presently solved for each partial wave by inverting a 34 X 34 supermatrix. At very high energies, larger dimensions may be required. The present version of the code uses a separable non-local phi N potential of finite range; other types of non-localities, or non- separable potentials, may be of physical interest.
This depends on the number of partial waves and the size of the supermatrix. The test case requires 60 sec on the UNIVAC 1108 (10 partial waves, 34 X 34 supermatrix).
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