wiki:NCNROutput1D_2DQxQy

Version 2 (modified by srkline, 12 years ago) (diff)

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The 2D "QxQy ASCII" output files of SANS data are of the format below. Based on the instrument settings, each pixel of the 2D detector data is converted into Qx and Qy. The 2D detector is a normal XY coordinate system when viewed from the neutron source. Qx and Qy both positive is a point in the upper right quadrant and both negative is a point in the lower left quadrant. What corrections have been applied to the data depend on what (if any) reduction steps were applied before exporting the file.

In each file there is a header of information describing the sample information (gleaned from the raw data file) and information about the processing steps that were taken to generate the reduced data file. The data is in a 8-column format where the 8 columns are:

1- Qx (1/Angstrom)
2- Qy (1/Angstrom)
3- I(Qx,Qy) (1/cm)
4-err I(QxQy?) (1/cm)
5- Qz (1/A)
6- SigmaQ Parallel (1/A)
7- SigmaQ Perpendicular (1/A)
8- fs Beamstop Shadow factor (0,1]

Note that the Q-values are set up (naturally) on an XY grid. The resolution function is most conveniently defined at each XY value in terms of the orthogonal directions - parallel to Q and perpendicular to Q.

The error on the intensity is currently calculated as the square root of the intensity. For later analysis, any error values that are zero, Inf, or NaN are set equal to the average error of the entire data set. A full error propagation through the data reduction is in progress.

(only a snippet of the file is shown here)

FILE: SILIC009.SA3_SRK_S109   CREATED: Fri, Jun 4, 2010 3:46:37 PM
LABEL: Silica 2 pct in D2O Scatt 1.3M                              
MON CNT   LAMBDA (A)  DET_OFF(cm)   DET_DIST(m)   TRANS   THICK(cm)
1e+08  6       20     1.33     0.7248     0.2
BCENT(X,Y)   A1(mm)   A2(mm)   A1A2DIST(m)   DL/L   BSTOP(mm)   DET_TYP  
106.8  64.59  50    3    5.4675    0.142    50.8    ORNL  
SAM: SILIC009.SA3_SRK_S109
BGD: SILIC004.SA3_SRK_S104,
EMP: SILIC003.SA3_SRK_S103,
DIV: PLEX_2NOV2007_NG3.DIV,
MASK: DEFAULT.MASK,
ABS Parameters (3-6): TSTAND=1;DSTAND=1;IZERO=1.2418e+05;XSECT=1
Average Choices: AVTYPE=QxQy_ASCII;SAVE=Yes;NAME=Auto;PLOT=Yes;

*** Data written from ABS folder and may not be a fully corrected data file ***
Data columns are Qx - Qy - I(Qx,Qy) - err(I) - Qz - SigmaQ_parall - SigmaQ_perp - fSubS(beam stop shadow)
ERROR WAVE IS ONLY AN ESTIMATE  - 6/2010
ASCII data created Fri, Jun 4, 2010 3:46:38 PM

-0.3778205	-0.2270851	0.1054546	0.3247378	0.09729926	0.02633375	0.002935865	1
-0.3747085	-0.2273637	0.1062517	0.3259627	0.09613394	0.02617764	0.002936665	1
-0.3715851	-0.2276406	0.09981947	0.3159422	0.09497544	0.02602152	0.002937462	1
-0.3684504	-0.2279159	0.09411432	0.3067806	0.09382387	0.02586539	0.002938257	1
-0.3653043	-0.2281895	0.08147036	0.2854301	0.09267932	0.02570928	0.002939048	1
-0.3621468	-0.2284615	0.1085722	0.329503	0.09154189	0.0255532	0.002939837	1
-0.3589782	-0.2287316	0.1018893	0.319201	0.09041167	0.02539716	0.002940621	1
-0.3557983	-0.2290001	0.1163103	0.341043	0.08928876	0.02524117	0.002941402	1


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