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Manuscript Title: Monte Carlo calculation of multiple scattering effects in thermal neutron scattering experiments.
Authors: J.R.D. Copley
Program title: SLOW NEUTRON MULTIPLE SCATTERING
Catalogue identifier: ACIC_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 7(1974)289
Programming language: Fortran.
Computer: IBM 360/195.
Operating system: OS/360 RELEASE 21.6.
RAM: 72K words
Word size: 32
Peripherals: disc.
Keywords: Solid state physics, Multiple scattering, Thermal Neutron scattering, Elastic coherent, Elastic incoherent Scattering, Inelastic scattering, Monte carlo method, Alpha-beta sampling Scheme.
Classification: 7.6.

Revision history:
Type Tit le Reference
adaptation 0001 SLAB GEOMETRY See below
adaptation 0002HORIZONTAL CYLINDER GEOMETRY See below
adaptation 0003 NEW ELSCAT SUBROUTINE See below
correction 000ACORRECTION 11/10/79 See below
correction B00ACORRECTION TO 0002 11/10/79 See below

Nature of problem:
In a thermal neutron scattering experiment, the measured cross section includes both single and multiple scattering events. The former can be obtained from the measurement by subtracting an estimate for the latter, which is generally a smoother function of scattering angle and thus can be calculated using an approximate scattering function.

Solution method:
The program is adapted from that of Bischoff. Given a scattering function the program tracks successive neutrons within the sample and/or sample container in a Monte Carlo fashion. At each scattering point, the response, within each time channel and for each detector, is calculated. A cut-off is imposed to avoid tracking neutron indefinitely. Single and multiple scattering contributions for each time channel and for each angle, are separately accumulated.

Restrictions:
The present program is limited to one geometry and to no more than eight scattering angles. The sample (and sample container) must be isotropic materials.

Unusual features:
The minimum high speed storage requirement is about 49000 words. If inelastic scattering is included, further high speed storage is required, the amount depending on how accurately the inelastic scattering functions are defined. In the present case an extra 26000 words are used to store these functions.

Running time:
Once the scattering function has been set up, the Monte Carlo loop takes 0.2 to 0.5 milliseconds per collision, per angle, per time channel. Typical running times for a complete problem are of order 1-10 min on the IBM 370/195. If elastic coherent scattering is to be calculated, the program may take considerably longer to obtain adequate statistics.

ADAPTATION SUMMARY
Manuscript Title: Monte Carlo calculation of multiple scattering effects in thermal neutron scattering experiments; modification to slab geometry.
Authors: J.R.D. Copley
Program title: 0001 SLAB GEOMETRY
Catalogue identifier: ACIC_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 9(1975)59
Programming language: Fortran.
Computer: IBM 360/195.
Operating system: OS/360 RELEASE 21.6.
RAM: 72K words
Word size: 32
Peripherals: disc.
Classification: 7.6.

Other versions:
Cat Id Title Reference
AAFR_v1_0 MSCAT85 CPC 40(1986)337

Nature of problem:
This adaptation modifies 'SLOW NEUTRON MULTIPLE SCATTERING' to calculate multiple scattering effects in a plane slab target.

ADAPTATION SUMMARY
Manuscript Title: Monte Carlo calculation of multiple scattering effects in thermal neutron scattering experiments; modification to horizontal cylinder geometry.
Authors: J.R.D. Copley
Program title: 0002HORIZONTAL CYLINDER GEOMETRY
Catalogue identifier: ACIC_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 9(1975)64
Programming language: Fortran.
Computer: IBM 360/195.
Operating system: OS/360 RELEASE 21.6.
RAM: 72K words
Word size: 32
Peripherals: disc.
Classification: 7.6.

Other versions:
Cat Id Title Reference
AAFR_v1_0 MSCAT85 CPC 40(1986)337

Nature of problem:
This adaptation modifies 'SLOW NEUTRON MULTIPLE SCATTERING' to calculate multiple scattering effects in a target consisting of multiple cylinders, with axes parallel to the scattering plane.

ADAPTATION SUMMARY
Manuscript Title: Monte Carlo calculation of multiple scattering effects in thermal neutron scattering experiments: improved computation of elastic coherent scattering intensities.
Authors: J.R.D. Copley
Program title: 0003 NEW ELSCAT SUBROUTINE
Catalogue identifier: ACIC_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 21(1981)431
Programming language: Fortran.
Classification: 7.6.

Nature of problem:
This adaptation comprises a new version of the subroutine ELSCAT which is used to compute the differential cross-section for elastic coherent scattering into a detector. An analytical procedure is employed. The new subroutine is superior to the old one both in terms of accuracy and computing time.

CORRECTION SUMMARY
Manuscript Title: Monte Carlo calculation of multiple scattering effects in thermal neutron scattering experiments. (C.P.C. 7(1974)289).
Authors: J.R.D. Copley
Program title: 000ACORRECTION 11/10/79
Catalogue identifier: ACIC_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 20(1980)459
Classification: 7.6.

CORRECTION SUMMARY
Manuscript Title: Monte Carlo calculation of multiple scattering effects in thermal neutron scattering experiments: modification to horizontal cylinder geometry. (C.P.C. 9(1975)64).
Authors: J.R.D. Copley
Program title: B00ACORRECTION TO 0002 11/10/79
Catalogue identifier: ACIC_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 20(1980)459
Classification: 7.6.