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1<html>
2<head>
3   <title>EXPGUI Tutorial #3</title>
4</head>
5
6<style>
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15<?
16   include("/var/www/include/navigation.inc");
17   include("/var/www/include/utility.inc");
18?>
19<blockquote>
20
21<CENTER>
22<H1>GSAS Nickel example using EXPGUI (part 3)</H1>
23</CENTER>
24<H1>
253. Add data (histograms) to the Experiment
26</H1>
27
28The next step in the tutorial is to add data. Note that
29GSAS uses the term
30histogram to refer to a powder diffraction data set.
31To add data, switch to the Histogram in EXPGUI pane and press the
32"Add New Histogram" button in the lower right.
33<img src="addhs1.gif" ALIGN=LEFT>
34This brings up the "add new histogram" dialog, to the left.
35Press on the upper "Select File" button for a dialog box to select
36a data file.
37
38<BR clear=left>
39<img src="addhs2.gif" ALIGN=LEFT>
40Select the appropriate file, in this case nickel.raw and press
41the "Open" button.
42
43At this stage, different things can happen.
44If the file is not correctly formatted,
45<A HREF="nickelnotes.html#reformat">a dialog will offer
46to convert the file to the correct format.</a>
47Also, in some cases, the data file specifies the name of the instrument
48parameter file. If so, that name will be loaded into the "Instrument
49Parameter file" box. If not, as in this case, the file must be selected
50by pressing the lower "Select File" button which creates a
51dialog box to select an instrument parameter file, similar
52to the one above.
53
54<BR clear=left>
55<img src="addhs3.gif" ALIGN=LEFT>
56After the appropriate instrument parameter file is located and selected,
57one must select the bank of data (if more than one) and the bank of the
58instrument parameters (if more than one) using the bank checkbuttons.
59Finally one must enter either the minimum d-space or
60maximum time-of-flight or two-theta to be used from the data (note that
61this value can be changed later if need be from EXPEDT). A
62good way to do this is to use
63<A HREF="nickelnotes.html#rawplot">RAWPLOT</A>
64to look at the data. This is done
65by pressing the "Run RAWPLOT" button at the
66lower right <A HREF="nickelnotes.html#rawplot">(example).</A>
67This invokes the GSAS RAWPLOT program. Note that you will need to specify the
68same data and instrument parameters file names to RAWPLOT to see a
69plot of the data.
70
71
72When all input is complete, press Add to run program EXPTOOL and read the
73data into the .EXP file.
74
75<BR clear=left>
76<img src="addhs4.gif" ALIGN=LEFT>
77The results from the EXPTOOL are shown in a separate box, so
78that errors can be noted.
79
80<BR clear=left>
81<img src="addhs5.gif" ALIGN=LEFT>
82The above procedure is then repeated for the third bank of data, but this
83time the maximum time-of-flight is changed to 1.5.
84<P>After Add is pressed, the EXPTOOL results are
85displayed and then the histogram panel is
86updated so that the diffraction parameters
87for each of the two histograms can be examined
88(see below).
89<BR clear=left>
90<img src="addhs6.gif">
91<BR clear=left>
92There is one deviation in the above
93compared to the tutorial in the GSAS manual.
94In that tutorial the
95data compression factor is set to 2 for the
96first histogram, averaging pairs
97of points to speed up
98the computations. This cannot be done from EXPGUI.
99If desired, it can be done using EXPEDT, but for
100most modern computers this tutorial will still run
101in seconds with no compression.
102
103<P><BR>(.EXP Snapshot:
104<A HREF="ftp://ftp.ncnr.nist.gov/pub/cryst/gsas/tutorials/nickel3.exp">
105nickel3.exp
106</A>)
107
108<BR clear=left><HR>
109Previous step: <A HREF="nickel2.html">
110Add a phase to the Experiment</A>
111<BR>
112Next step: <A HREF="nickel4.html">
113 Change a profile parameter</A>
114
115<HR>
116</blockquote>
117<P><font size=-1><A HREF="MAILTO:crystal@NIST.gov?subject=WWW page <?=$PHP_SELF?>">Comments, corrections or questions: crystal@NIST.gov</A></font><BR>
118<font size=-1><? lastmod(); ?> </font>
119<BR>$Revision: 930 $ $Date: 2009-12-04 23:14:35 +0000 (Fri, 04 Dec 2009) $
120</body>
121</html>
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