Component Manual for the Neutron Ray-Tracing Package McStas, version 3.8.6

9.10  The TOFRes_sample McStas Component

Sample for TOF resolution function calculation.

Identification

Description

An inelastic sample with completely uniform scattering in both solid angle and energy. This sample is used together with the TOFRes_monitor component and (optionally) the mcresplot front-end to compute the resolution function of all time-of-flight instruments. The method of time focusing is used to optimize the simulations.

The shape of the sample is either: 1. Hollow cylinder (Please note that the cylinder **must** be specified with both a radius and a wall-thickness!) 2. A massive, rectangular box specified with dimensions xwidth, yheight, zdepth. (i.e. **withouht** a thickness)

hollow cylinder shape **must** be specified with both a radius and a wall-thickness. The box is

The scattered neutrons will have directions towards a given target and detector arrival time in an interval of time_width centered on time_bin. This target area is default disk shaped, but may also be rectangular if specified focus_xw and focus_yh or focus_aw and focus_ah, respectively in meters and degrees. The target itself is either situated according to given coordinates (x,y,z), or setting the relative target_index of the component to focus at (next is +1). This target position will be set to its AT position. When targeting to centered components, such as spheres or cylinders, define an Arm component where to focus at.

Example: TOFRes_sample(thickness=0.001, radius=0.01, yheight=0.04, focus_xw=0.025, focus_yh=0.025, time_bin=3e4, time_width=200, target_x=0, target_y=0, target_z=1)

Input parameters

Parameters in boldface are required; the others are optional.

Name

Unit

Description

Default

thickness

m

Thickness of hollow cylinder in (x,z) plane

0

radius

m

Outer radius of hollow cylinder

0.01

yheight

m

vert. dimension of sample, as a height

0.05

focus_r

m

Radius of sphere containing target

0.05

time_bin

us

position of time bin

20000

time_width

us

width of time bin

10

f

1

Adaptive time-shortening factor

50

target_x

0

target_y

m

position of target to focus at

0

target_z

.5

focus_xw

m

horiz. dimension of a rectangular area

0

focus_yh

m

vert. dimension of a rectangular area

0

focus_aw

deg

horiz. angular dimension of a rectangular area

0

focus_ah

deg

vert. angular dimension of a rectangular area

0

xwidth

m

horiz. dimension of sample, as a width

0

zdepth

m

depth of sample

0

target_index

1

relative index of component to focus at, e.g. next is +1

0

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