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1<html>
2<head>
3   <title>EXPGUI</title>
4   <meta name="keywords" content="crystallography, Rietveld, diffraction,
5   GSAS, EXPGUI">
6</HEAD>
7<style>
8A:link {text-decoration:none}
9A:vlink {text-decoration:none}
10</style>
11
12<BODY BGCOLOR="#FFFFFF"
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15
16<?
17   include("/var/www/include/navigation.inc");
18   include("/var/www/include/utility.inc");
19?>
20<blockquote><font face="arial, helvetica, sans-serif">
21
22<TABLE BORDER BGCOLOR="#FFFF40" ALIGN=RIGHT>
23<TR><TH><A  Href="expgui.html">EXPGUI top</A> 
24</TH><TH><A Href="expgui4.html">Next page</A>
25</TH><TH><A Href="expgui2.html">Previous page</A>
26</TH></TR></TABLE><BR CLEAR=ALL>
27
28<center><h1>
29<HR noshade width="75%" size="2" align="center">
30EXPGUI, part 3
31<HR noshade width="75%" size="2" align="center">
32</h1></center>
33<h3>A.3 Histogram panel</h3> 
34<DL><DL>
35The histogram panel is used to edit background
36and diffractometer constants for a histogram, as well as
37set damping and refinement flags for these parameters.
38<P>
39If
40<A href="expgui.html#multiplehistogram">
41"Multiple Histogram Selection" mode</A> is set to "All",
42this panel is disabled. For other settings of this mode,
43groups of histograms can be selected and modified
44collectively.
45<P>
46If the EXPTOOL program
47<A href="expgui.html#installation">(see the installation instructions)</A>
48is installed, a button for adding histograms will
49appear on the bottom right on this panel, as seen below. If the
50program is not properly installed, no errors occur, but the button
51does not appear.
52<P>
53Note that the order that histograms appear in this
54panel is determined by the <a href="expguic.html#sorthist">"Sort histograms by"</a> option in
55the Options Menu.
56</DL></DL>
57</blockquote>
58<img SRC="3.gif" align=TEXTTOP alt="EXPGUI Screen snapshot">
59<blockquote>
60<br clear=all>
61
62<a name="EditBackground"></a>
63<h3>A.3.1 Editing background</h3> 
64<DL><DL>
65<img SRC="3b1.gif" align=TEXTOP alt="EXPGUI Screen snapshot">
66When the button labeled "Edit Background", (or "Globally Edit Background"
67or in the case where <A href="expgui.html#multiplehistogram">
68"Multiple Histogram Selection" mode</A> is set to a single histogram type)
69is pressed, a window such as the one
70to the left is displayed. In the case where background coefficients
71are being edited for more than one histogram
72(<A href="expgui.html#multiplehistogram">
73"Multiple Histogram Selection" mode</A> must be
74set to a single histogram type) the entry boxes will appear blank
75and only those terms that are filled in will be changed when the "Set"
76button is pressed.
77This option is mostly useful when changing the background function or the
78number of terms for several histograms at a single time.
79Note that no changes are made until the "Set"
80button is pressed.
81<P>
82
83The "Fit Background Graphically" button is displayed only when a single
84histogram is selected for background editing. When this button is
85pressed, the <A HREF="liveplot.html#bkgedit">BKGEDIT</A> program is
86called to fit a background function to user-input fixed background points.
87See the <A HREF="liveplot.html#bkgedit">BKGEDIT documentation</A> for more
88information.
89</DL></DL>
90<br clear=all>
91
92<a name="EditAbsorption"></a>
93<h3>A.3.2 Editing absorption/reflectivity</h3> 
94<DL><DL>
95<img SRC="3h.gif" align=RIGHT alt="EXPGUI Screen snapshot">
96The refinement flag and damping factor for correction for absorption
97effects (or for flat-plate samples, reflectivity corrections) can be
98seen in a box near the bottom of the panel.
99The terms and the type of correction used
100are set using the "Edit Abs./Refl." button in this box. Pressing this
101button creates a window, shown to the right. A message is shown in the
102bottom of the window summarizing information about the selected correction.
103<P>
104<a name="AbsorptionSanity"></a>
105Please note, each correction is only appropriate for certain types of data
106and frequently the correction must be fixed rather than refined. It is
107wise to read the "Powder absorption factor" section of the GSAS manual
108(p 138-140 in 1/19/01 edition) before using this correction.
109Since some combinations of data types and correction types are unlikely --
110but not impossible
111(for example, a cylindical absorption correction and K-alpha1,2 radiation)
112EXPGUI will generate a warning message, such as the one below,
113but not all inappropriate actions can be prevented.
114The user must ultimately understand the role of the correction
115and the nature of the experiment to decide what is appropriate.
116<br clear=all>
117<img SRC="3h1.gif" align=TEXTTOP alt="EXPGUI Screen snapshot">
118<br clear=all>
119</DL></DL>
120<br clear=all>
121
122<a name="EditParm"></a>
123<h3>A.3.3 Global Editing of Parameters</h3> 
124<DL><DL>
125It is possible to access parameters and settings for more than one histogram
126at a time when a multiple selection of a specific histogram type
127is allowed
128(see
129<A href="expgui.html#multiplehistogram">
130"Multiple Histogram Selection" mode</A>).
131In this mode, the histogram panel
132appears slightly differently, as is shown below.
133</DL></DL>
134</blockquote>
135<img SRC="3c.gif" align=TEXTTOP alt="EXPGUI Screen snapshot">
136<blockquote>
137<br clear=all>
138<DL><DL>
139<img SRC="3d.gif" align=LEFT alt="EXPGUI Screen snapshot">
140Pressing a refinement flag checkbox will set all
141selected histogram refinement flags either off or on.
142Pressing a "Globally Edit..." button, will allow a parameter to be set.
143For example, the window to the left shows how
144a diffractometer constant can be
145edited for more than one histogram
146<P>
147A similar window is also used to globally set the
148<A href="expgui4.html">Phase Fraction</A> in
149<A href="expgui.html#multiplehistogram">
150"Multiple Histogram Selection"</A> mode.
151<br clear=all>
152
153</DL></DL>
154
155<a name="AddHist"></a>
156<h3>A.3.4 Entering New Diffractograms</h3> 
157<DL><DL>
158Pressing the "Add New Histogram" button creates the dialog
159shown below. This dialog can be used to enter diffraction data to be used
160in the refinement, or can be used to define parameters for pattern
161simulation, through use of the "dummy histogram" option
162<a href="#Dummy">(see below)</a>.
163<img SRC="3e.gif" align=LEFT alt="EXPGUI Screen snapshot">
164<br clear=all>
165In the case where diffraction data will be input,
166a data file and an instrument parameter file must be
167selected using the "Select File" buttons. The limit for reflection
168generation (maximum energy or two-theta, or minimum d-space or TOF)
169must be entered, as well as the units.
170If more than one bank is defined, either in the data file or in the
171instrument parameter file, the bank must be selected as well.
172Note that the data range can be edited at a later time using the
173<a href="excledt.html">EXCLEDT</a> utility.
174<P>
175<img SRC="3e3.gif" align=RIGHT alt="EXPGUI Screen snapshot">
176
177<h4>
178<IMG SRC="new.gif" HEIGHT=13 WIDTH=36 alt="New!">
179Plotting Diffraction Patterns</H4>
180
181To view a plot of a data file, so that the range of the data
182may be viewed, the RAWPLOT program may be invoked using the "Run RAWPLOT"
183button. Note that EXPGUI cannot communicate the names
184of the data and instrument parameter files to RAWPLOT, so they must be
185reentered. The window to the right is shown to aid doing this.
186When files have been selected in the "add histogram" menu, the "put name in
187clipboard" button can be used to place the file name into the
188clipboard. The appropriate paste function (for example the Paste button
189for the DOS window) can be used to avoid typing in the file name.
190<P>
191
192<h4>
193<IMG SRC="new.gif" HEIGHT=13 WIDTH=36 alt="New!">
194Editing Instrument Parameter Files</H4>
195
196Instrument parameter files can be edited using the "Edit File"
197button to call the <a href="expgui.html#INSTEDIT">INSTEDIT</a> utility.
198Alternately, to create a new instrument parameter file, you can
199call the same utility using the "instedit" option in the Powder menu.
200Refer to the documentation on
201<a href="expgui.html#INSTEDIT">INSTEDIT</a> to see how this utility functions.
202
203<P><h4>
204<IMG SRC="new.gif" HEIGHT=13 WIDTH=36 alt="New!">
205Adding Multiple Diffraction Patterns</H4>
206
207For working with instruments with large numbers of detectors,
208when the number of datasets in the data file matches the number of
209instrument parameters, the button "Add multiple banks" becomes available.
210When this button is pressed, a new window is created that shows a
211checkbutton and a two-theta max (or E-max/TOF-min) for each bank. Banks
212may be selected and pressing a button causes all selected banks to be loaded.
213
214<P>
215<br clear=all>
216<img SRC="3e1.gif" align=RIGHT alt="EXPGUI Screen snapshot">
217<a name="Dummy"></a><h4>Simulating Diffraction Patterns</H4>
218When the dummy histogram option is selected, diffraction data can
219be simulated based a set of experimental constants
220described in an instrument parameter file.
221Note that most of these instrumental parameters,
222such as wavelength or DIFC can be edited on this panel or
223on the <A HREF="expgui5.html">profile</A> panel
224(the simulated pattern is also affected by constants on the
225<A HREF="expgui4.html">scaling</A> panel.)
226The 2-theta/energy/TOF
227range to be used for the computation, as well as the step size,
228must be entered before pressing the "Add" button.
229Note that once the histogram is added, this range and step size
230cannot be edited within EXPGUI at present. However,
231EXPEDT can be used to change these values.
232<br clear=all>
233<P>
234<a name="AddHistErr"></a>
235<img SRC="3e2.gif" align=LEFT alt="EXPGUI Screen snapshot">
236If errors are detected in the input, an error message is displayed
237detailing where the errors are found. Otherwise, the EXPTOOL program is run
238and the output is optionally displayed
239(See <a href="expguic.html#exptoolout">Show EXPTOOL output</a>).
240</DL></DL>
241<br clear=all>
242<P>
243<h3>A.3.5 Editing the Data Range & Excluded Regions</h3> 
244<DL><DL>
245The button at the bottom of the panel, labeled
246"Set Data Limits & Excluded Regions" invokes
247the <a href="excledt.html">EXCLEDT</a> utility, which is used to
248modify the lower and upper data limits and can be used to add or delete
249excluded regions.
250</DL></DL>
251
252<h3>A.3.6 Setting Histogram Flags</h3> 
253<DL><DL>
254<img SRC="3f.gif" align=RIGHT alt="EXPGUI Screen snapshot">
255The button at the bottom of the panel, labeled "Set Histogram Use Flags" invokes
256a menu where the "Use"/"Do not use" flag for powder histogram can be set.
257When this flag is turned off, the histogram is ignored for
258subsequent computations, effectively removing from the experiment.
259<P>
260When these "Use" flags are changed, it is necessary to run POWPREF,
261to propogate the changes. After the "Save" button is pressed, a prompt such
262as the example below, is generated to run POWPREF. Note that GENLES may
263fail if POWPREF is not run after changing these flags.
264<br clear=all>
265<P>
266<img SRC="3g.gif" align=TEXTTOP alt="EXPGUI Screen snapshot">
267<br clear=all>
268</DL></DL>
269
270<h3>A.3.7 Setting Phase Flags</h3> 
271<DL><DL>
272If there is more than one phase present in the refinement,
273an extra box appears at the top of the panel to allow phase flags
274to be selected. This allows a phase to be used in some histograms
275but not in others. It also offers a simple way to effectively "delete" a
276phase by removing it from all histograms. Be sure to rerun POWPREF after
277changing the phase flags.
278</DL></DL>
279</blockquote>
280<img SRC="3a.gif" align=TEXTTOP alt="EXPGUI Screen snapshot">
281<blockquote>
282<br clear=all>
283<hr>
284<TABLE BORDER BGCOLOR="#FFFF40" ALIGN=RIGHT>
285<TR><TH><A  Href="expgui.html">EXPGUI top</A> 
286</TH><TH><A Href="expgui4.html">Next page</A>
287</TH><TH><A Href="expgui2.html">Previous page</A>
288</TH></TR></TABLE>
289
290<P><font size=-1><A HREF="MAILTO:crystal@NIST.gov?subject=WWW page <?=$PHP_SELF?>">Comments, corrections or questions: crystal@NIST.gov</A></font><BR>
291<font size=-1><? lastmod(); ?> </font>
292<br>$Revision: 930 $ $Date: 2009-12-04 23:14:35 +0000 (Fri, 04 Dec 2009) $
293</blockquote>
294</body>
295</html>
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