diff --git a/Code/Mantid/Framework/DataHandling/src/SetSampleMaterial.cpp b/Code/Mantid/Framework/DataHandling/src/SetSampleMaterial.cpp
index ba3e5cc35af45a7c5fa0b57c3325b2cf01987d3a..0dee22ce3060abd1f5488f3dbe1150b4cefecd65 100644
--- a/Code/Mantid/Framework/DataHandling/src/SetSampleMaterial.cpp
+++ b/Code/Mantid/Framework/DataHandling/src/SetSampleMaterial.cpp
@@ -57,7 +57,7 @@ void SetSampleMaterial::init() {
"formulas per cubic angstrom will be used instead of "
"calculated");
declareProperty("ZParameter", EMPTY_DBL(), mustBePositive,
- "Number of atoms in the unit cell");
+ "Number of formula units in unit cell");
declareProperty("UnitCellVolume", EMPTY_DBL(), mustBePositive,
"Unit cell volume in Angstoms^3. Will be calculated from the "
"OrientedLattice if not supplied.");
@@ -202,20 +202,6 @@ void SetSampleMaterial::exec() {
// determine the sample number density
double rho = getProperty("SampleNumberDensity"); // in Angstroms-3
double zParameter = getProperty("ZParameter"); // number of atoms
- if (isEmpty(rho)) {
- double unitCellVolume = getProperty("UnitCellVolume"); // in Angstroms^3
-
- // get the unit cell volume from the workspace if it isn't set
- if (isEmpty(unitCellVolume) && expInfo->sample().hasOrientedLattice()) {
- unitCellVolume = expInfo->sample().getOrientedLattice().volume();
- g_log.notice() << "found unit cell volume " << unitCellVolume
- << " Angstrom^-3\n";
- }
- // density is just number of atoms in the unit cell
- // ...but only calculate it if you have both numbers
- if ((!isEmpty(zParameter)) && (!isEmpty(unitCellVolume)))
- rho = zParameter / unitCellVolume;
- }
// get the scattering information - this will override table values
double coh_xs = getProperty("CoherentXSection"); // in barns
@@ -273,6 +259,21 @@ void SetSampleMaterial::exec() {
// normalize the accumulated number by the number of atoms
neutron = (1. / numAtoms) *
neutron; // funny syntax b/c of operators in neutron atom
+ if (isEmpty(rho)) {
+ double unitCellVolume = getProperty("UnitCellVolume"); // in Angstroms^3
+
+ // get the unit cell volume from the workspace if it isn't set
+ if (isEmpty(unitCellVolume) && expInfo->sample().hasOrientedLattice()) {
+ unitCellVolume = expInfo->sample().getOrientedLattice().volume();
+ g_log.notice() << "found unit cell volume " << unitCellVolume
+ << " Angstrom^-3\n";
+ }
+ // density is just number of atoms in the unit cell
+ // ...but only calculate it if you have both numbers
+ if ((!isEmpty(zParameter)) && (!isEmpty(unitCellVolume)))
+ rho = numAtoms * zParameter / unitCellVolume;
+ }
+
b_avg = b_avg / numAtoms;
b_sq_avg = b_sq_avg / numAtoms;
@@ -289,6 +290,20 @@ void SetSampleMaterial::exec() {
fixNeutron(neutron, coh_xs, inc_xs, sigma_atten, sigma_s);
// create the material
+ if (isEmpty(rho)) {
+ double unitCellVolume = getProperty("UnitCellVolume"); // in Angstroms^3
+
+ // get the unit cell volume from the workspace if it isn't set
+ if (isEmpty(unitCellVolume) && expInfo->sample().hasOrientedLattice()) {
+ unitCellVolume = expInfo->sample().getOrientedLattice().volume();
+ g_log.notice() << "found unit cell volume " << unitCellVolume
+ << " Angstrom^-3\n";
+ }
+ // density is just number of atoms in the unit cell
+ // ...but only calculate it if you have both numbers
+ if ((!isEmpty(zParameter)) && (!isEmpty(unitCellVolume)))
+ rho = zParameter / unitCellVolume;
+ }
mat.reset(new Material(chemicalSymbol, neutron, rho));
}
diff --git a/Code/Mantid/Framework/DataHandling/test/SetSampleMaterialTest.h b/Code/Mantid/Framework/DataHandling/test/SetSampleMaterialTest.h
index 2acae0e8b23ea83b2ccfb3a04d7b14c211149126..8254569fc531afc2f9d9019a5cf7a88a33369d2a 100644
--- a/Code/Mantid/Framework/DataHandling/test/SetSampleMaterialTest.h
+++ b/Code/Mantid/Framework/DataHandling/test/SetSampleMaterialTest.h
@@ -54,9 +54,9 @@ public:
TS_ASSERT_THROWS_NOTHING( setmat->setPropertyValue("InputWorkspace", wsName) );
TS_ASSERT_THROWS_NOTHING( setmat->setPropertyValue("ChemicalFormula","Al2-O3") );
- TS_ASSERT_THROWS_NOTHING( setmat->setPropertyValue("SampleNumberDensity","0.0236649") );
- TS_ASSERT_THROWS_NOTHING( setmat->setPropertyValue("ScatteringXSection","15.7048") );
- TS_ASSERT_THROWS_NOTHING( setmat->setPropertyValue("AttenuationXSection","0.46257") );
+ TS_ASSERT_THROWS_NOTHING( setmat->setPropertyValue("SampleNumberDensity","0.1183245") );
+ TS_ASSERT_THROWS_NOTHING( setmat->setPropertyValue("ScatteringXSection","3.1404") );
+ TS_ASSERT_THROWS_NOTHING( setmat->setPropertyValue("AttenuationXSection","0.0925") );
TS_ASSERT_THROWS_NOTHING( setmat->execute() );
TS_ASSERT( setmat->isExecuted() );
@@ -70,9 +70,9 @@ public:
//can get away with holding pointer as it is an inout ws property
const Material *m_sampleMaterial = &(testWS->sample().getMaterial());
- TS_ASSERT_DELTA( m_sampleMaterial->numberDensity(), 0.0236649, 0.0001 );
- TS_ASSERT_DELTA( m_sampleMaterial->totalScatterXSection(NeutronAtom::ReferenceLambda), 15.7048, 0.0001);
- TS_ASSERT_DELTA( m_sampleMaterial->absorbXSection(NeutronAtom::ReferenceLambda), 0.46257, 0.0001);
+ TS_ASSERT_DELTA( m_sampleMaterial->numberDensity(), 0.1183245, 0.0001 );
+ TS_ASSERT_DELTA( m_sampleMaterial->totalScatterXSection(NeutronAtom::ReferenceLambda), 3.1404, 0.0001);
+ TS_ASSERT_DELTA( m_sampleMaterial->absorbXSection(NeutronAtom::ReferenceLambda), 0.0925, 0.0001);
checkOutputProperties(setmat,m_sampleMaterial);
@@ -102,7 +102,7 @@ public:
TS_ASSERT( setmat->isExecuted() );
const Material *m_sampleMaterial = &(testWS->sample().getMaterial());
- TS_ASSERT_DELTA( m_sampleMaterial->numberDensity(), 0.0236649, 0.0001 );
+ TS_ASSERT_DELTA( m_sampleMaterial->numberDensity(), 0.1183245, 0.0001 );
TS_ASSERT_DELTA( m_sampleMaterial->totalScatterXSection(NeutronAtom::ReferenceLambda), 3.1404, 0.0001);
TS_ASSERT_DELTA( m_sampleMaterial->absorbXSection(NeutronAtom::ReferenceLambda), 0.0925, 0.0001);
diff --git a/Code/Mantid/docs/source/algorithms/SetSampleMaterial-v1.rst b/Code/Mantid/docs/source/algorithms/SetSampleMaterial-v1.rst
index 4f4d227297d632c06f8053bce94fb363c09cce4c..4587a87638772187a635e6d8cb467f36f5c8d4a1 100644
--- a/Code/Mantid/docs/source/algorithms/SetSampleMaterial-v1.rst
+++ b/Code/Mantid/docs/source/algorithms/SetSampleMaterial-v1.rst
@@ -61,7 +61,7 @@ Number Density
The number density is defined as
-.. math:: \rho_n = \frac{ZParameter}{UnitCellVolume}
+.. math:: \rho_n = \frac{N_{atoms}ZParameter}{UnitCellVolume}
It can can be generated in one of two ways:
@@ -69,5 +69,22 @@ It can can be generated in one of two ways:
2. Specifying the ``ZParameter`` and the ``UnitCellVolume`` (or letting
the algorithm calculate it from the OrientedLattice on the
``InputWorkspace``).
+
+Linear Absorption Coefficients
+##############################
+.. math:: \mu_s = \rho_n \frac{1}{N_{atoms}}\sum_{i}s_{i}n_{i} \text{ units of 1/cm}
+.. math:: s = \sigma_{total scattering}
+.. math:: \mu_a = \rho_n \frac{1}{N_{atoms}}\sum_{i}a_{i}n_{i} \text{ units of 1/cm}
+.. math:: a = \sigma_{absorption} (\lambda=1.8)
+
+References
+----------
+
+The data used in this algorithm comes from the following paper.
+
+#. Varley F. Sears, *Neutron scattering lengths and cross sections*, Neutron News **3:3** (1992) 26
+ `doi: 10.1080/10448639208218770`_
+
+
.. categories::