Madsen and Hill Variable Count Time (VCT) code and Mark Bowden's VCTCONV for DOS

Madsen and Hill Variable Count Time (VCT) code (Fortran Source and DOS executable). Can create the count time files, as well as diffractometer scripts in Philips 1710 command format.

• http://www.ccp14.ac.uk/ccp/ccp14/ftp-mirror/csirominerals-anon-ftp/pub/xtallography/variable-count-time/

• Relevant References:
  • "Collection and analysis of powder diffraction data with near-constant counting statistics", I. C. Madsen and R. J. Hill, J. Appl. Cryst. (1994). 27, 385-392, http://www.iucr.org/cgi-bin/paper?hz0014
  • I. C. Madsen and R. J. Hill, Adv. X-ray Anal. (1992), 35, 39-47
  • W. I. F. David, Accuracy in Powder Diffraction, Abstract P2.6 NIST Special Publication No. 846, Page 210, (1992) National Institute of Standards and Technology, Gaithersburg, MD, USA.

• Note: Fullprof and Winplotr can handle both GSAS ESD format and Madsen and Hill VCT data files without converting to other formats.

Mark Bowden's VCTCONV for DOS:

• http://www.ceramics.irl.cri.nz/Convert.htm

Variable Count Time data

Following in an image showing some variable count time data collected for refinement purposes (where sub-cell and super-cell reflections over the entire range have been collected with near identical counting statistics).

Other screen images show the data displayed normalized to look like Fixed Count Time (FCT) data, and zooming up to show i) trace peaks collected with similar counting statistics to the major peaks; ii) normally strong sub-cell and weak super-cell reflections have been collected with near identical counting statistics and iii) VCT data showing sub-cell and super-cell reflections normalised to look like Fixed Count Time data.

Native Variable Count Time data

VCT data normalized to look like Fixed Count Data

Zoomed VCT data showing a trace and major peak

Zoomed VCT data showing sub-cell and super-cell reflections

Zoomed VCT data normalised to look like Fixed Count Time data

Converting Madsen and Hill VCT data to GSAS ESD format

The following shows an extra of some Variable Count Time data in Madsen and Hill format.

CUSTOM VARIABLE COUNT TIME DATA COLLECTION - Lachlan Cranswick
Min step time =   0.25  
XRDTIME calculation run at 15:41  on  24 Feb 2002 
                                                  
   3.000    .025 140.000      Custom VCT data collection 24 Feb 2002      
   .25        38   .25        38   .25        30   .25        29   .25        25
   .25        31   .25        32   .25        29   .25        38   .25        29
   .25        33   .25        33   .25        19   .25        25   .25        41
   .25        28   .25        32   .25        24   .25        25   .25        23
   .25        25   .25        26   .25        26   .25        25   .25        22
   .25        25   .25        22   .25        19   .25        22   .25        25
   .25        17   .25        31   .25        29   .25        27   .25        33
   .25        28   .25        24   .25        23   .25        31   .25        30
   .25        19   .25        16   .25        24   .25        17   .25        20
   .25        30   .25        24   .25        16   .25        14   .25        22
   .25        20   .25        21   .25        14   .25        22   .25        15
   .25        19   .25        13   .25        28   .25        25   .25        19
   .25        16   .25        16   .25        13   .25        16   .25        22
   .25        23   .25        15   .25        17   .25        17   .25        17
   .25        17   .25        21   .25        20   .25        13   .25        12
   .25        19   .25        17   .25        19   .25        19   .25        16
   .25        17  2.40       185  2.40       149  2.40       145  2.40       169
  2.40       139  2.40       200  2.40       139  2.40       182  2.40       154
  2.40       149  2.40       160  2.40       161  2.40       176  2.40       176
  2.40       160  2.40       187  2.40       167  2.40       179  2.40       199
  2.40       182  2.40       172  2.40       184  2.40       213  2.40       196
  2.40       226  2.40       215  2.40       215  2.40       244  2.40       231
  2.40       238  2.40       244  2.40       235  2.40       244  2.40       292
  2.40       291  2.40       336  2.40       327  2.40       342  2.40       374
  2.40       379  2.40       399  2.40       442  2.40       519  2.40       538
  2.40       571  2.40       606  2.40       667  2.40       778  2.40       862
  2.40       966  2.40      1140  2.40      1327  2.40      1624  2.40      1928
  2.40      1881  2.40      1699  2.40      1110  2.40       575  2.40       273
  2.40       200  2.40       171  2.40       163  2.40       149  2.40       143
  2.40       138  2.40       131  2.40       145  2.40       133  2.40       128
  2.40       103  2.40       124  2.40       119 99.00      4704 99.00      4693
 99.00      4726 99.00      4626 99.00      4638 99.00      4547 99.00      4651
 99.00      4563 99.00      4528 99.00      4585 99.00      4726 99.00      4502
 99.00      4507 99.00      4632 99.00      4554 99.00      4842 99.00      4801

To convert this into GSAS ESD format, run VCTCONV, input the starting Madsen and Hill VCT data file and specify the name of the GSAS ESD file (in this example, example.gsa) and then press the F2 to complete the conversion.

Following is an extract from the resulting GSAS ESD file.

      Custom VCT data collection 24 Feb 2002                                    
BANK    1       5481      1097 CONST        300.00      2.50     0     0     ESD
  152.00   24.66  152.00   24.66  120.00   21.91  116.00   21.54  100.00   20.00
  124.00   22.27  128.00   22.63  116.00   21.54  152.00   24.66  116.00   21.54
  132.00   22.98  132.00   22.98   76.00   17.44  100.00   20.00  164.00   25.61
  112.00   21.17  128.00   22.63   96.00   19.60  100.00   20.00   92.00   19.18
  100.00   20.00  104.00   20.40  104.00   20.40  100.00   20.00   88.00   18.76
  100.00   20.00   88.00   18.76   76.00   17.44   88.00   18.76  100.00   20.00
   68.00   16.49  124.00   22.27  116.00   21.54  108.00   20.78  132.00   22.98
  112.00   21.17   96.00   19.60   92.00   19.18  124.00   22.27  120.00   21.91
   76.00   17.44   64.00   16.00   96.00   19.60   68.00   16.49   80.00   17.89
  120.00   21.91   96.00   19.60   64.00   16.00   56.00   14.97   88.00   18.76
   80.00   17.89   84.00   18.33   56.00   14.97   88.00   18.76   60.00   15.49
   76.00   17.44   52.00   14.42  112.00   21.17  100.00   20.00   76.00   17.44
   64.00   16.00   64.00   16.00   52.00   14.42   64.00   16.00   88.00   18.76
   92.00   19.18   60.00   15.49   68.00   16.49   68.00   16.49   68.00   16.49
   68.00   16.49   84.00   18.33   80.00   17.89   52.00   14.42   48.00   13.86
   76.00   17.44   68.00   16.49   76.00   17.44   76.00   17.44   64.00   16.00
   68.00   16.49   77.08    5.67   62.08    5.09   60.42    5.02   70.42    5.42
   57.92    4.91   83.33    5.89   57.92    4.91   75.83    5.62   64.17    5.17
   62.08    5.09   66.67    5.27   67.08    5.29   73.33    5.53   73.33    5.53
   66.67    5.27   77.92    5.70   69.58    5.38   74.58    5.57   82.92    5.88
   75.83    5.62   71.67    5.46   76.67    5.65   88.75    6.08   81.67    5.83
   94.17    6.26   89.58    6.11   89.58    6.11  101.67    6.51   96.25    6.33
   99.17    6.43  101.67    6.51   97.92    6.39  101.67    6.51  121.67    7.12
  121.25    7.11  140.00    7.64  136.25    7.53  142.50    7.71  155.83    8.06
  157.92    8.11  166.25    8.32  184.17    8.76  216.25    9.49  224.17    9.66
  237.92    9.96  252.50   10.26  277.92   10.76  324.17   11.62  359.17   12.23
  402.50   12.95  475.00   14.07  552.92   15.18  676.67   16.79  803.33   18.30
  783.75   18.07  707.92   17.17  462.50   13.88  239.58    9.99  113.75    6.88
   83.33    5.89   71.25    5.45   67.92    5.32   62.08    5.09   59.58    4.98
   57.50    4.89   54.58    4.77   60.42    5.02   55.42    4.81   53.33    4.71
   42.92    4.23   51.67    4.64   49.58    4.55   47.52    0.69   47.40    0.69
   47.74    0.69   46.73    0.69   46.85    0.69   45.93    0.68   46.98    0.69
   46.09    0.68   45.74    0.68   46.31    0.68   47.74    0.69   45.47    0.68
   45.53    0.68   46.79    0.69   46.00    0.68   48.91    0.70   48.49    0.70
   48.44    0.70   48.57    0.70   51.32    0.72   52.71    0.73   55.84    0.75
   54.98    0.75   51.04    0.72   46.29    0.68   43.89    0.67   42.51    0.66

Import the data into GSAS and either start or continue the refinement. GSAS and Brian Toby's EXPGUI will display the data as a fixed count time equivalent.