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Manuscript Title: LPOTT: pion and kaon elastic scattering from spin 1/2 nuclei in momentum space.
Authors: R.H. Landau
Program title: LPOTT
Catalogue identifier: AAVL_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 28(1982)109
Programming language: Fortran.
Computer: CDC CYBER 170/72.
Operating system: NOS 1.4.
RAM: 42K words
Word size: 60
Peripherals: disc.
Keywords: Nuclear physics, Optical potential, Pion, Kaon, Elastic scattering, Charge exchange Scattering, Momentum space, Spin 1/2 nuclei, Mutliple scattering Theory, Sigma(theta), sigma tot.
Classification: 17.14.

Nature of problem:

Solution method:
A theoretical momentum-space optical potential is generated from elementary meson-nucleon amplitudes and realistic nuclear matter and spin form factors. The potential is expanded in Legendre series and the resulting one-dimensional, coupled Lippmann-Schwinger integral equations are reduced to linear equations and solved by matrix inversion. Differential and total scattering cross sections, polarizations, and coordinate space wave functions are calculated for both the elastic and single charge exchange scattering of pi+, pi-, pi0, K+, or K0. The theory includes nuclear spin 1/2 with realistic form factors, nucleon recoil and binding (2- or 3- body subenergies), Lorentz invariant relations between amplitudes and kinematic variables in different reference frames (angle and momentum transformations), the most recent elementary phase shifts, theoretical off-energy-shell behaviour generated from separable potential models, Pauli effects, an "exact" inclusion of the Coulomb force, and a second-order potential to represent the effects of true absorption.

Restrictions:
Spin 0 times spin 0, spin 0 times spin1/2,
0<~ Tphi<~ 1.5 GeV, 0<~ Tk<~ 1 GeV.
No. of meson-nucleus(nucleon) partial waves<= 30 (8) in com.
Number of grid points for numerical integration of wave equation <=32 (must modify one DIMENSION statement to increase). Exact Coulomb only for elastic scattering (not charge exchange). Variety of nuclear densities possible, but not at all energies. Variety of kinematic prescriptions possible.

Running time:
Most of the running time is used to set up the potential matrix. The test case, phi+ 12C scattering at 50 MeV with 10 partial waves, takes ~~ 20 s without Pauli modifications and ~~ 28 s with Pauli modifications. These times are nearly doubled for a spin 1/2 nucleus, and doubled again for charge excahnge since LPOTT does phi+ (K+) and then phio(Ko). As the nucleus gets larger and/or the energy increases, an increase in running time approximately proportional to the increased number of partial waves will occur. However, the program saves some time by use of the Born approximation for higher partial waves.