vSANS Data Reduction Protocol

Make sure to save (cntrl+S) your file periodically throughout the reduction process. The software may 

crash if handling a large number of files. Saving prevents loss of progress.

1. Open Igor Pro (latest version at https://www.wavemetrics.com/software/igor-pro-8)

2. In the Macros menu, select Load VSANS Procedures (latest version at 

https://www.nist.gov/ncnr/data-reduction-analysis/sans-software → ‘Latest GitHub Release’)

3. Choose to Yes or No to using back detector (usually No)

4. In the green VSANS Reduction Controls panel, select Pick Path and choose the folder where your 

raw VSANS files are located.

5. Select ‘File Catalog’ from the Reduction Controls panel.

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6. In the white File Catalog, left click on the middle right open beam transmission file (e.g. Open 

Beam NG0 MR Trans). Select Load RAW from menu that appears.

7. Navigate to the Middle tab of the tan WORK_RAW panel that appears. Draw a box around the 

beam (high intensity spot on the detector) by clicking and dragging so that the whole beam is 

included. Left click inside the selection box and select V_UpdateBoxCoords. Kill WORK_RAW 

panel by shift-clicking the x in the top right corner of the panel.

8. In the File Catalog, check that the Group_IDs match for the transmission and scattering files of 

each sample. If they do not match, these can be patched by selecting the Group_ID cell to be 

patched, correcting the Group_ID number and navigating to VSANS → Nexus File Corrections →

Patch GroupID using CatTable. Other file corrections can be made using other options in the 

VSANS menu.

9. In the Reduction Controls panel (green), select Transmission. In the brown 

V_TransmissionPanel, left click on the Open Beam pop-up menu. Select the Open Beam file for 

which the box coordinates were updated in Step 7 (XY Box numbers should change to box 

coordinates instead of the default 1;2;3;4;).

10. In V_TransmissionPanel, left click Transmission pop-up menu. Select transmission file of data 

being reduced. Select either Calculate to calculate the transmission for a single file currently in 

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the Sample pop-up menu or Calculate All In Popup to calculate a single transmission for all of 

the files in the Sample pop-up menu. When finished, select Done.

*Only samples having Group_IDs matching the Group_ID of the file currently selected in the 

Transmission pop-up menu are listed in the Sample pop-up menu.

11. Navigate to Reduction tab in Reduction Controls panel (green). Select Build Protocol.

12. In the lilac (light greyish red) VSANS Reduction Protocol menu, select the Background file 

(Blocked Beam) from the pop-up menu. Select Empty Cell file from pop-up menu. Repeat for 

Sensitivity and Mask files. Directions for making mask files can be found in the VSANS help files.

13. In the Absolute section of the VSANS Reduction Protocol panel, select set ABS MF. Select Empty 

Beam Flux from the Absolute Scaling panel that appears. Select the Open Beam file that was 

used for calculating transmission in Step 9. Press Continue. Select DIV File. Press Continue.

14. In the Average section of the VSANS Reduction Protocol panel, select set AVERAGE params. 

Choose Type of Average (typically Circular). Choose Binning Type* (typically F1-M2xTB-B).

*Every detector after ‘x’ in a binning type is removed from the data averaging.

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15. In Data Catalog, click on sample scattering data and choose Load RAW from menu. Close 

WORK_RAW by shift-clicking x in the top right corner. Select Trim in the VSANS Reduction 

Protocol panel. In the data plot that appears, select appropriate Bin Type from pop-up menu in 

top left corner. Remove points as desired* by using the V_TrimPointsTable. When finished, 

select Done on plot window and shift-click x in top right corner of V_TrimPointsTable.

*Typically, 7-10 points are removed at low q (Beg_pts) for MLR (Middle Left-Right Average) for 

the beamstop.

16. In VSANS Reduction Protocol panel, select Save Protocol. Save with appropriate name 

identifying the VSANS configuration (e.g. NG0) for which the protocol applies. A new protocol 

must be built for each VSANS configuration used. Protocols can be edited by choosing Recall 

Protocol and saving it as the same name after completing edits. Select Done when finished.

17. Select Reduce Multiple Files from the VSANS Reduction Controls Panel. In the salmon-colored 

Muliple VSANS File Reduction panel, select the appropriate VSANS protocol for the data being 

reduced (ensure that the protocol corresponds to the same VSANS configuration used to 

generate the sample data).

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18. In the File Catalog, select the data files to reduce by clicking and dragging. Select Send to MRED

from the menu that appears when releasing the dragged click. The file names will appear in the 

Muliple VSANS File Reduction panel. Click Reduce All Files in Popup to reduce the selected data

files. Choose a maximum of approx. 20 files at a time to reduce. Reducing too many files at once 

can cause the program to crash. When finished reducing files, click Done Reducing. All reduced 

files should have been output as .ABS files, which can be plotted in Igor or imported into 

SasView (https://www.sasview.org/download/) for data analysis.

19. To plot reduced VSANS files in Igor, navigate to the 1-D Ops tab in the VSANS Reduction Controls 

panel. Select Plot. In the bright green Plot Manager panel, scroll to the .ABS file to be plotted. 

Multiple files can be selected by holding shift while scrolling and clicking. When files are 

selected, click Load File(s). If the box ‘Plot data on loading’ beneath Load File(s) is checked, 

dialog boxes will appear to help the plotting process (e.g. appending data to the same plot).

20. Make sure to save your project by pressing cntrl+s.

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