source: sasmodels/ref/intro.html @ 68532f3

gh-pages
Last change on this file since 68532f3 was 68532f3, checked in by ajj, 8 years ago

Adding docs
  • Property mode set to 100644
File size: 4.9 KB
Line 
1<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
2  "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
3
4
5<html xmlns="http://www.w3.org/1999/xhtml">
6  <head>
7    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
8   
9    <title>1. Introduction &mdash; Sasmodels</title>
10   
11    <link rel="stylesheet" href="../_static/haiku-site.css" type="text/css" />
12    <link rel="stylesheet" href="../_static/pygments.css" type="text/css" />
13   
14    <script type="text/javascript">
15      var DOCUMENTATION_OPTIONS = {
16        URL_ROOT:    '../',
17        VERSION:     '0.9',
18        COLLAPSE_INDEX: false,
19        FILE_SUFFIX: '.html',
20        HAS_SOURCE:  true
21      };
22    </script>
23    <script type="text/javascript" src="../_static/jquery.js"></script>
24    <script type="text/javascript" src="../_static/underscore.js"></script>
25    <script type="text/javascript" src="../_static/doctools.js"></script>
26    <script type="text/javascript" src="http://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS-MML_HTMLorMML"></script>
27    <link rel="top" title="Sasmodels" href="../index.html" />
28    <link rel="up" title="2. SAS Model Reference" href="index.html" />
29    <link rel="next" title="2. Model Functions" href="models/index.html" />
30    <link rel="prev" title="2. SAS Model Reference" href="index.html" /> 
31  </head>
32  <body>
33      <div class="header"><h1 class="heading"><a href="../index.html">
34          <span>Home</span></a></h1>
35        <h2 class="heading"><span>1. Introduction</span></h2>
36      </div>
37      <div class="topnav">
38     
39        <p>
40        «&#160;&#160;<a href="index.html">2. SAS Model Reference</a>
41        &#160;&#160;::&#160;&#160;
42        <a class="uplink" href="../index.html">Contents</a>
43        &#160;&#160;::&#160;&#160;
44        <a href="models/index.html">2. Model Functions</a>&#160;&#160;»
45        </p>
46
47      </div>
48      <div class="content">
49       
50       
51  <div class="section" id="introduction">
52<span id="models-intro"></span><h1>1. Introduction<a class="headerlink" href="#introduction" title="Permalink to this headline">¶</a></h1>
53<p>Many of our models use the form factor calculations implemented in a c-library provided by the NIST Center for Neutron
54Research and thus some content and figures in this document are originated from or shared with the NIST SANS Igor-based
55analysis package.</p>
56<p>This software provides form factors for various particle shapes. After giving a mathematical definition of each model,
57we show the list of parameters available to the user. Validation plots for each model are also presented.</p>
58<p>Instructions on how to use SasView itself are available separately.</p>
59<p>To easily compare to the scattering intensity measured in experiments, we normalize the form factors by the volume of
60the particle</p>
61<div class="math">
62\[P(\vec q) = \frac{P_o(\vec q)}{V} = \frac{1}{V} F(\vec q) F^*(\vec q)\]</div>
63<p>with</p>
64<blockquote>
65<div>F(vec q) = intintint dVrho(vec r) e^{-ivec q cdot vec r}</div></blockquote>
66<p>where <span class="math">\(P_0(\vec q)\)</span> is the un-normalized form factor, <span class="math">\(\rho(\vec r)\)</span> is the scattering length density at a given
67point in space and the integration is done over the volume <span class="math">\(V\)</span> of the scatterer.</p>
68<p>For systems without inter-particle interference, the form factors we provide can be related to the scattering intensity
69by the particle volume fraction</p>
70<div class="math">
71\[I(\vec q) = \Phi P(\vec q)\]</div>
72<p>Our so-called 1D scattering intensity functions provide <span class="math">\(P(Q)\)</span> for the case where the scatterer is randomly oriented. In
73that case, the scattering intensity only depends on the length of <span class="math">\(Q\)</span> . The intensity measured on the plane of the SAS
74detector will have an azimuthal symmetry around <span class="math">\(Q=0\)</span>.</p>
75<p>Our so-called 2D scattering intensity functions provide <span class="math">\(P(Q,\phi)\)</span> for an oriented system as a function of a
76<span class="math">\(q\)</span> vector in the plane of the detector. We define the angle <span class="math">\(\phi\)</span> as the angle between the <span class="math">\(q\)</span> vector and the horizontal
77($x$) axis of the plane of the detector.</p>
78<p>For information about polarised and magnetic scattering, see <a class="reference external" href="polar_mag_help.html">here</a>.</p>
79</div>
80
81
82      </div>
83      <div class="bottomnav">
84     
85        <p>
86        «&#160;&#160;<a href="index.html">2. SAS Model Reference</a>
87        &#160;&#160;::&#160;&#160;
88        <a class="uplink" href="../index.html">Contents</a>
89        &#160;&#160;::&#160;&#160;
90        <a href="models/index.html">2. Model Functions</a>&#160;&#160;»
91        </p>
92
93      </div>
94
95    <div class="footer">
96        &copy; Copyright 2014, sasview team.
97      Created using <a href="http://sphinx-doc.org/">Sphinx</a> 1.2.3.
98    </div>
99  </body>
100</html>
Note: See TracBrowser for help on using the repository browser.