[ Identification | Description | Input parameters | Output parameters | Links ]

# The `Incoherent_test` Instrument

This instrument allows to compare incoherent scattering from different McStas sample components.

## Identification

- Site: tests
- Author: Peter Willendrup, Erik Knudsen, Aziz Aziz Daoud-aladine
- Origin: RISOE
- Date: August 14th, 2007
- Version: 0.1

## Description

     This instrument allows to compare incoherent scattering from different McStas
     sample components:

     V_sample
     PowderN
     Single_crystal
     Isotropic_sqw

    Examples:

    Compare incoherent scattering from all four sample comps, beamstop in place:
    (V_multiples=0: V_sample algo identical to PowderN algo - NO multiples
     V_multiples: V_sample performs crude estimate for multiple scattering)

      mcrun Incoherent_test -d Some_directory -N4 SAMPLE=1,4 STOP=1 V_multiples=0

    Compare incoherent scattering and direct beam attenuation for PowderN, Single_crystal
    and Isotroic_sqw:

      mcrun Incoherent_test -d Some_other_directory -N3 SAMPLE=2,4 STOP=0

    Have a closer look of direct beam attentuation for PowderN, Single_crystal
    and Isotroic_sqw (has the side-effect that back-scattered neutrons are absorbed):

      mcrun Incoherent_test -d Some_third_directory -N3 SAMPLE=2,4 STOP=0 DB=1

## Input parameters

Parameters in boldface are required; the others are optional.

Name | Unit | Description | Default
--- | --- | --- | ---
L_min | AA | Minimum wavelength of neutrons | 0.5
L_max | AA | Maximum wavelength of neutrons | 7
SAMPLE | 1 | 1==Vanadium 2==PowderN 3==Single_Crystal 4==Isotropic_sqw |
STOP | 1 | Beamstop inserted? (Needed in case of comparison between V and SX/sqw). | 0
V_multiples | 1 | Use crude estimate for multiple scattering in V_sample? | 1
Order | 1 | Maximum order of multiple scattering in SX/sqw | 0
INC | barns | Incoherent scattering cross section | 5.08
ABS | barns | Absorption cross section | 5.08
DB | 1 | Direct Beam monitor inserted? (Side-effect: absorbs 'backscattered' neutrons). | 0
ISISFACE | string | ISIS moderator face to look at | "hydrogen"

## Links

- Source code for `Incoherent_test.instr`.
- Validation of Single_crystal is now in progress!

[ Identification | Description | Input parameters | Output parameters | Links ]