.. _ISIS_SANS_User_File-ref: ================ User File Format ================ .. contents:: Table of Contents :local: Instrument Selection -------------------- This should be the first command in a user file for the following instruments: - LOQ - SANS2D BACK ---- BACK is used to specify a time region in which to measure the (time-independent) neutron background count level. The background is calculated and subtracted from the monitor and transmission spectra before the data are rebinned into wavelength. It is possible to set the TOF time window for all monitors or just one specific monitor. Syntax ^^^^^^ .. code-block:: none BACK/MON/TIMES t1 t2 BACK/Mm/TIMES t1 t2 BACK/Mm t1 t2 BACK/Mm/OFF Qualifiers ^^^^^^^^^^ **/MON/TIMES** Set the start and end of the time of flight window assumed for all monitors **/M** Used to set the time of flight window that should be used for a single specified monitor **/Mm/OFF** This command is only relevant to use after /MON/TIMES to turn off background for a specific monitor. Parameters ^^^^^^^^^^ **t1 t2** Neutron times of flight (microseconds) specifying the time region to be considered as the background level **m** The spectrum number of the spectrum produced by the monitor of interest (note spectrum numbers start at 1 as opposed to workspace indices which are normally offset by 1) DET --- DET specifies which detector data is to be corrected, or whether detector position encoder values are to be corrected. Note for now that the /CORR commands only have an effect on SANS2D. Syntax ^^^^^^ .. code-block:: none DET/CORR/FRONT/qualifier [parameter] DET/CORR/REAR/qualifier [parameter] DET/FRONT DET/REAR DET/BOTH DET/MERGED DET/MERGE DET/MAIN DET/HAB DET/RESCALE rescale DET/SHIFT shift DET/RESCALE/FIT [Q1 Q2] DET/SHIFT/FIT [Q1 Q2] Qualifiers ^^^^^^^^^^ **/X x1** Applies a correction to the detector X encoder value **/Y y1** Applies a correction to the detector Y encoder value **/Z z1** Applies a correction to the detector Z encoder value **/ROT d1** Applies a correction to the detector Rotary encoder value **/RADIUS r** Increase the apparent radius from the rotation axis of the detector to the active plane **/SIDE s** Translate the rotation axis of the detector perpendicular to the plane of the detector. **/FRONT** When used as DET/CORR/FRONT correct data from the Front detector (if SANS2D) or High-Angle Bank (if LOQ). When used as DET/FRONT set the analysis to apply to the FRONT detector. **/HAB** This command applies only to LOQ. It is equivalent to DET/FRONT **/REAR** When used as DET/CORR/REAR correct data from the Rear detector (if SANS2D) or Main detector (if LOQ). When used as DET/REAR set the analysis to apply to the REAR detector. **/MAIN** This command applies only to LOQ. It is equivalent to DET/REAR **/BOTH** When used as DET/BOTH set the analysis to apply both detectors. It is equivalent to set the SANS Dialog Analysis to Detector Bank -> both. **/MERGED** When used as DET/MERGED set the analysis to apply both detectors and them merge them in one. It is equivalent to set the SANS Dialog Analysis to Detector Bank -> merged. **/MERGE** Same as /MERGED **/RESCALE rescale** Rescale front detector data, defaults to 1.0. Multiplying the front detector reduced data by this number **/SHIFT shift** Shift const background of front detector data, defaults to 0.0 **/RESCALE/FIT [Q1 Q2]** If specified fit RESCALE so front and back data match. Optionally provide fitting range Q1 to Q2. If not specified will use entire overlapping Q region of FRONT and REAR detector data **/SHIFT/FIT [Q1 Q2]** If specified fit SHIFT so front and back data match **/OVERLAP Q1 Q2** If specified is the region between which the merged data will be used Parameters ^^^^^^^^^^ **x1** Amount (mm) by which to correct the detector X encoder value from the run log file **y1** Amount (mm) by which to correct the detector Y encoder value from the run log file **z1** Amount (mm) by which to correct the detector Z encoder value from the run log file **d1** Amount (degrees) by which to correct the detector Rotary encoder value from the run log file **r** Amount (mm) by which to correct the detector RADIUS encoder value **s** Amount (mm) by which to correct the detector SIDE encoder value FIT --- FIT specifies whether the calculated transmission data should be fitted to a simple function. Subsequent data treatment then uses values interpolated from the function. Fitting can improve the statistical quality of transmission data and is implemented by CalculateTransmission. Syntax ^^^^^^ .. code-block:: none FIT/TRANS/CLEAR or FIT/TRANS/OFF FIT/TRANS/LIN [w1 w2] or FIT/TRANS/LINEAR [w1 w2] or FIT/TRANS/STRAIGHT [w1 w2] FIT/TRANS/LOG [w1 w2] or FIT/TRANS/YLOG [w1 w2] FIT/MONITOR time1 time2 FIT/TRANS/[CAN/|SAMPLE/][LIN|LOG|POLYNOMIAL[2|3|4|5]] Qualifiers ^^^^^^^^^^ **/TRANS/CLEAR or TRANS/OFF** Disable fitting of transmissions **/TRANS/LIN** or **/TRANS/LINEAR** or **/TRANS/STRAIGHT** Use a linear fit of the form Y=mX+C **/TRANS/LOG** or **/TRANS/YLOG** Use a fit of the form Y=exp(aX+C) **/TIME time1 time2** time1 and time2 will be the XMin and XMax passed to the algorithm RemoveBins. RemoveBins is called the all monitors, for transmission and normalisation **/TRANS/POLYNOMIAL** # for # bigger than 2 Use a Polynomial of order # of the form Y = c0 + c1X + c2X^2 + ... Optional Qualifiers ^^^^^^^^^^^^^^^^^^^ **/TRANS/SAMPLE/...** Configure the settings for FIT just for the sample workspace. Ex: FIT/TRANS/SAMPLE/POLYNOMIAL3 - applies a third order polynomial to fit sample workspace for transmission. **/TRANS/CAN/...** Configure the settings for FIT just for the can workspace. Ex: FIT/TRANS/SAMPLE/LIN - fit the transmission of the can using a linear function. If SAMPLE or CAN is not provided, it is assumed that the FIT/TRANS option applies to both. Parameters ^^^^^^^^^^ **w1 w2** [optional] Neutron wavelengths (Angstroms) specifying the fitting range Default if omitted is to use the full wavelength range GRAVITY ------- GRAVITY specifies whether detector data should be corrected for the ballistic effects of gravity on the neutrons. This correction is particularly important at long sample-detector distances and long wavelengths. Syntax ^^^^^^ .. code-block:: none GRAVITY ON GRAVITY OFF GRAVITY/LEXTRA=l1 Qualifiers ^^^^^^^^^^ **/LEXTRA** Specifies the extra length in m that can be added to the gravity correction. The extra length is only taken into account when GRAVITY is explicitly set to ON. The LEXTRA qualifier needs be currently placed into a separate line. The default value is set to 0.0m which is used when the qualifier is not explicitly specified. Parameters ^^^^^^^^^^ **ON** Use gravity correction **OFF** Do not use gravity correction **l1** The extra length in m. COMPATIBILITY ------------- COMPATIBILITY specifies whether the new backend should be run in compatibility mode such that it produces identical results to the old backend. Syntax ^^^^^^ .. code-block:: none COMPATIBILITY ON COMPATIBILITY OFF Parameters ^^^^^^^^^^ **ON** Use compatibility mode **OFF** Don't use compatibility mode L --- L specifies various limits that configure or constrain the data reduction process. Note that the command is L and not LIMIT! Syntax ^^^^^^ .. code-block:: none L/PHI[/NOMIRROR] d1 d2** L/Q/ q1 q2 [dq[/LIN]] or L/Q q1 q2 [dq[/LOG]] L/Q q1 dq1 q3 dq2 q2 or L/Q q1 -dq1 q2 -dq2 q3 (for logarithmic steps) L/Q/RCut c L/Q/WCut c L/QXY qxy1 qxy2 [dqxy[/LIN]] or L/QXY qxy1 qxy2 [dqxy[/LOG]] L/QXY qxy1 dqxy1 qxy2 dqxy2 qxy3 [/LIN]] or L/QXY qxy1 dqxy1 qxy2 dqxy2 qxy3 [/LOG]] L/R r1 r2 L/WAV l1 l2 [dl[/LIN] or L/WAV l1 l2 [dl[/LOG] L/WAV l1 dl1 l3 dl2 l2 [/LIN] or L/WAV l1 dl1 l3 dl2 l2 [/LOG] L/EVENTSTIME rebin_str Qualifiers ^^^^^^^^^^ **/PHI[/NOMIRROR]** Specifies the azimuthal sector of the detector to be included in a 2D data reduction, useful for processing anisotropic data The optional /NOMIRROR qualifier determines whether the mirror image sector with should be excluded (i.e. if say phi is specified 85 to 95 should -95 to -85 also be included) **/Q** Specifies the Q range for a 1D reduction **/Q/RCut** Specifies the RadiusCut property that is passed to Q1D in mm. **/Q/WCut** The number following this will be passed to Q1D as the WaveCut property, in angstrom. **/QXY** Specifies the Q range for a 2D reduction **/R** Specifies the radial limits on the detector within which the radial integration of the data should be performed **/WAV** Specifies the wavelength limits to be used in the data reduction **/EVENTSTIME** Used to specifies a rebinning string to be applied to event mode data **/LIN** [optional, default] Specifies that the step size or increment given is a constant value; ie, the bins are to be equally spaced The step size or increment should be given in the same units as the data X axis **/LOG** [optional] Specifies that the step size or increment given is a geometric progression; ie, the bins will get further apart The step size or increment should be given in %/100; a typical value to match the wavelength resolution might be 5% Default is to use /LIN if omitted Parameters ^^^^^^^^^^ **d1 d2** Minimum and maximum azimuthal angles (degrees) specifying the sector of interest; 0 degrees (or 360 degrees) is at 3 O'clock, 180 degrees (or -180 degrees) is at 9 O'clock To correct about the Equator use, say, L/PHI -30 30 To correct about the Meridian use, say, L/PHI 60 120 **q1 q2** Minimum and maximum Q values (/Angstrom) over which a 1D reduction is to be performed; this will ultimately be constrained by the detector position and available wavelengths As a guide, try q1~0.002 & q2~0.3 (for SANS2D) or q1~0.006 & q2~0.3 (for LOQ) **dq** [optional] Q step size The magnitude of this value will depend on whether a /LIN or /LOG qualifier is specified For variable step sizes in logarithmic form, use -dq, and remove the /LOG qualifier **dq1,q3,dq2** Where dq1, q3 & dq2 are specified the data will be binned from q1->q3 in steps of dq1, and from q3->q2 in steps of dq2 **qxy1 qxy2** Minimum and maximum Qx (and Qy) values (/Angstrom) over which a 2D reduction is to be performed; this will ultimately be constrained by the detector position and available wavelengths For simplicity the same limits are applied to both axes NB qxy1 should always be set to 0! **dqxy** [optional] Qxy step size The magnitude of this value will depend on whether a /LIN or /LOG qualifier is specified It is recommended that only linear bins are used for 2D data reductions **dqxy1,qxy3,dqxy2** Where dqxy1, qxy3 & dqxy2 are specified the data will be binned from qxy1->qxy3 in steps of dqxy1, and from qxy3->qxy2 in steps of dqxy2 **r1 r2** Radial limits (mm) between which the radial integration of the data should be performed Generally r1 will be slightly larger than the shadow of the beamstop on the detector, and r2 will be the distance from the centre of the beamstop to the furthest corner of the detector **l1 l2** Minimum and maximum wavelength values (Angstroms) to be used during data reduction As a guide, try l1~1.5 & l2~14 (for SANS2D) or l1~2.2 & l2~10.0 (for LOQ) **dl** [optional] Wavelength step size The magnitude of this value will depend on whether a /LIN or /LOG qualifier is specified **dl1,l3,dl2** Where dl1, l3 & dl2 are specified the data will be binned from l1->l3 in steps of dl1, and from l3->l2 in steps of dl2 MASK ---- MASK commands clear or implement detector spatial or time masks. Masked regions of the detector or time-of-flight spectra are not included in any data reduction. Note that the shadow of the beam stop, and the corners of the detector, are masked automatically. Also note that there is no equivalent in Mantid of the COLETTE box mask MASK x1 x2 y1 y2 where X & Y were specified in mm. Syntax ^^^^^^ .. code-block:: none MASK/CLEAR[/TIME] MASK[/REAR/FRONT/HAB] Hn[>Hm] or MASK Vn[>Vm] - to mask single wires or 'strips' MASK[/REAR/FRONT/HAB] Hn>Hm+Vn>Vm - to mask a rectangular 'box' MASK Ssp1[>Ssp2] MASK/TIME t1 t2 or MASK/T t1 t2 MASK/LINE width angle [x y] Qualifiers ^^^^^^^^^^ **/CLEAR** Clears any detector masks in operation Without any /TIME qualifier only spatial masks are cleared; with a /TIME qualifier only time masks are cleared **/TIME** or **/T** [optional] Specifies that the command applies to time masks **/LINE** Masking arm only has effect for SANS2D **/REAR** Specifies that the mask applies to the Rear detector (if SANS2D) and the Main detector (if LOQ). This is default if not specified **/FRONT** Specifies that the mask applies to the Front detector (if SANS2D) and the High-Angle Bank (if LOQ) **/HAB** This command is equivalent to /FRONT Parameters ^^^^^^^^^^ **Hm Hn** Specify VERTICAL wires (columns) on the detector For SANS2D, 0