Getting Started

Before starting the program, you should have in your current directory the configuration file simres00.cfg describing your instrument and a parameter file (*.res, RESCAL input file format). If the program doesn't find simres00.cfg, it creates one with default values. This will not correspond to your TAS setup exactly and the results can be quite different. Check therefore, that you have correct values written in the TAS configuration file.

At the beginning, the program shows a short logo and prompts you for the batch file name:

batch file :

give the name of your job file (e.g. strain.job from the ./demo folder) or press <enter> to work interactively.

In the interactive mode, the program asks you to select energy units,

Energy In m[eV] Or T[Hz]? (meV)m
Units Are [meV]

absolute path, where the data files will be searched for,

Path to the spectra files - ../data/

and the name of the file with the RESCAL input parameters or experimantal data compatible with the ILL format,

Name of a parameter or data file - strain.res

and waits for your commands,

ResTrax> _

You can type the help command to view a brief list of commands accepted by the program and their meaning. If a file simres.hlp is present in the current directory, program lists this file instead of the built-in list.  You can edit "simres.hlp" to your convenience.


Input Parameters

The input parameters are taken from three sources:

RESCAL input file

To keep the compatibility with the RESCAL parameter set, we use the same format of the input file, adding only six variables - the monochromator and analyzer curvatures and the sample diameter and height - which are often modified. These parameters can be read (file), modified, listed (list) and saved (save, save as) via the command line interpreter exactly as in the RESCAL program. The file format is just ASCII list of numbers in free format in the order corresponding to the following list.
 

Example: List of the parameters, which can be modified from the command line:

ResTrax>list

DM = 3.13500   DA = 3.13500
ETAM = .00   ETAA = .00 ETAS = .01
SM = -1.   SS = 1. SA = -1.
KFIX = 4.47753   FX = 2.
ALF1 = 500.00 ALF2 = 500.00 ALF3 = 500.00 ALF4 = 500.00
BET1 = .00    BET2 = .00    BET3 = .00    BET4 = .00
AS = 5.6576  BS = 5.6576  CS = 5.6576
AA = 90.0000 BB = 90.0000 CC = 90.0000
AX = -1.0000 AY = -1.0000 AZ = .0000
BX = .0000   BY = .0000   BZ = -1.0000
QH = -.2500  QK = -.2500  QL = 4.0000 EN = 8.2800
DH = .0100   DK = .0100   DL = .0000  DE = .0000
GH = 1.0000  GK = 1.0000  GL = .0000  GMOD = -19.0000
ROMH = .090  ROMV = 1.500 ROAH = .190 ROAV = 3.2000
SDI = 1.00   SHI = 2.00
DTH = 1.5

To  modify QH,QK,QL and EN, type e.g.

ResTrax>qh .25 .25 4 8.3
QH = 0.2500000 QK = 0.2500000 QL = 4.000000 EN = 8.300000
 

List of variables recognized by the command interpreter:
 
variable
description
units
DM,DA dhkl  of monochromator and analyzer 
Å
ETAM,ETAA,ETAS mosaic widths (fwhm) of monochromator, analyzer and sample
min.
SM,SS,SA  scattering sense for monochromator, analyzer and sample (+-1)
 
KFIX, FX length of the fixed neutron wave-vector; FX=1 fixed ki; FX=2 fixed kf
Å
ALF1 .. ALF4 divergence (horizontal) of the horizontal soller collimators
=0 no collimator, >500 course collimator (no lamellae)
min.
BET1 .. BET4 the same  vertically
 
AS,BS,CS parameters of the sample unit cell 
Å
AA,BB,CC angles of the sample unit cell 
deg.
AX,AY,AZ
BX,BY,BZ
components of the two vectors defining the scattering plane
 
QH,QK,QL,EN position of the center of scan in momentum and energy 
rlu, en
DH,DK,DL,DE scan increments in Q and E
rlu, en
GH,GK,GL,GMOD components of the gradient of the dispersion surface and its module 
rlu,  en/rlu
ROMH,ROMV horizontal and vertical curvatures (1/radius) of monochromator
m-1
ROAH,ROAV the same for analyzer
m-1
SDI,SHI sample diameter and height
cm
DTH step for detector scan (powder diffractometer)
min

rlu  ...  reciprocal lattice units
en  ...  energy units, meV or THz according to the initial choice


TAS configuration file

On contrary to the original Cooper & Nathans method, RESTRAX needs a couple of additional parameters describing in more details the TAS components and their distances. These parameters are stored in the configuration file (simres00.cfg by default). The program reads this file each time any command is executed, so that the user can edit (and save) its content in another window to modify the parameters as if from the command line.

You can also edit your configuration file interactively.

Configuration file format:

Each component in the file is described by 2 rows, the first one (actually not read by the program) contains head with the parameter names, the second  one contains  parameter values in free format. All dimensions are given in [cm].

title (max.60 characters):
sample setup for RESTRAX 4.6
This name will appear on the printed output.

source (shape,diameter,width,height):
0   10.   8.   8.
Source shapecan be circular (0), rectangular (1) or elliptical (2), diameteris used if shape=0, widthand heightis used if shape>1.

n-guide A(gap,length,hor1,hor2,ver1,ver2,ro[m-1], gh, gv [Ni nat.]. nlam,dlam):
0.  370.   3.8   3.1   20.   20.   0  2.   2.  1    1
n-guide B (present, distance,length,hor1,hor2,ver1,ver2,ro[m-1], gh, gv [Ni nat.]. nlam,dlam):
1  590.  8750.   3  3   20.   20.   3.704e-5  2.   2.  1    1

This items describe in-pile collimation, typically neutron guide, but possibly also windows in the shutter etc.. Together with the "collimator 1" it permits to define neutron guide or more complicated in pile collimation.  The first parameter in section B specifies whether these 2 segments are present (>0 yes, 0 no). The other parameters have the meaning common for all "collimator components".

monochromator (chi,aniz.,poiss.,thick.,height,length, segments hor.,vert.,slabs ):
10.0 1  0.3   1.0   25.   9.     1    25   5
chi    ... crystal cutting angle [deg], 0 for the symmetric Bragg reflection
aniz    ... ratio btw. the vertical and horizontal mosaicity
poiss ... Poisson constant for the elastically bent crystals (usually about 0.3)
thick.,height,length   ... crystal dimensions
segments  : 3 integers defining the number of segments horizontally, vertically and the number of slabs in a sandwich. The last number is optional.

analyzer (chi,aniz.,poiss.,thick.,height,length, segments hor.,vert.,slabs ):
0.0   1  0.15   0.9   12.  12.0    1     3
The same as for the monochromator.

detector (shape,diameter,width,height):
1       4.0      3.0      5.0
The same as for the source.

distances (l1,l2,l3,l4):
900. 210. 150. 70.
Distances between the source, monochromator, sample , analyzer and detector. If the n-guide is present, the first distance is measured from the exit of the guide, otherwise from the source.

1st collimator (distance,length,hor1,hor2,ver1,ver2,ro[m-1], gh, gv [Ni nat.]. nlam,dlam):
50.  900.   3.5    3.5   20  20    0.  2.0  2.0  1   1
2nd collimator A (gap,length,hor1,hor2,ver1,ver2,ro[m-1], gh, gv [Ni nat.]. nlam,dlam):
1.    0.   20.    20.   20.  20    0.  0.   0.   0   0
2nd collimator B (distance,length,hor1,hor2,ver1,ver2,ro[m-1], gh, gv [Ni nat.]. nlam,dlam):
140. 45.    9.     2.25  7.0  2.0  0.  0.   0.   0   0    45   0.025
3nd collimator (distance,length,hor1,hor2,ver1,ver2,ro[m-1], gh, gv [Ni nat.]. nlam,dlam):
1.   45.   0.1     9.    2.0  7.0  0.  0.   0.   0   0
4th collimator (distance,length,hor1,hor2,ver1,ver2,ro[m-1], gh, gv [Ni nat.]. nlam,dlam):
10.  10.   20.    20.   20.  20.   0.  0.   0.   0   0

These items describe the collimators between the source (after n-guide), monochromator, sample , analyzer and detector. The meaning of parameters is described in the section on "collimator components". The collimator between monochromator and sample has 2 sections. The 1st number of the A-section is the gap (not distance) between the both sections.