diff --git a/Code/Mantid/Framework/CurveFitting/inc/MantidCurveFitting/CalculateMSVesuvio.h b/Code/Mantid/Framework/CurveFitting/inc/MantidCurveFitting/CalculateMSVesuvio.h
index bd3255b05fab2b90aa2bb706787f937dca69cc8e..71b9767435f032f9d4564ec8ef53d4dd5ee160a6 100644
--- a/Code/Mantid/Framework/CurveFitting/inc/MantidCurveFitting/CalculateMSVesuvio.h
+++ b/Code/Mantid/Framework/CurveFitting/inc/MantidCurveFitting/CalculateMSVesuvio.h
@@ -102,7 +102,6 @@ private:
double generateTOF(const double gaussTOF, const double dtof,
const double dl1) const;
bool generateScatter(const Kernel::V3D &startPos, const Kernel::V3D &direc,
- const Kernel::V3D &detPos,
double &weight, Kernel::V3D &scatterPt) const;
std::pair<double, double> calculateE1Range(const double theta,
const double en0) const;
diff --git a/Code/Mantid/Framework/CurveFitting/src/CalculateMSVesuvio.cpp b/Code/Mantid/Framework/CurveFitting/src/CalculateMSVesuvio.cpp
index 237848852d2317728124fb73a67674ba05185915..1b9aea72dde7c708db9ec294cd7861830a9b50c6 100644
--- a/Code/Mantid/Framework/CurveFitting/src/CalculateMSVesuvio.cpp
+++ b/Code/Mantid/Framework/CurveFitting/src/CalculateMSVesuvio.cpp
@@ -32,7 +32,8 @@ using Geometry::ParameterMap;
using Geometry::Track;
namespace {
-const size_t MAX_SCATTER_PT_TRIES = 100;
+/// Number of times to try generating a scatter point before giving up
+const size_t MAX_SCATTER_PT_TRIES = 500;
/// Conversion constant
const double MASS_TO_MEV =
0.5 * PhysicalConstants::NeutronMass / PhysicalConstants::meV;
@@ -120,7 +121,8 @@ void CalculateMSVesuvio::init() {
"Workspace to store the calculated total scattering counts");
declareProperty(
new WorkspaceProperty<>("MultipleScatteringWS", "", Direction::Output),
- "Workspace to store the calculated multiple scattering counts summed for all orders");
+ "Workspace to store the calculated multiple scattering counts summed for "
+ "all orders");
}
/**
@@ -350,10 +352,9 @@ void CalculateMSVesuvio::calculateMS(const size_t wsIndex,
* @param simulCounts Simulation object used to storing the calculated number of
* counts
*/
-void
-CalculateMSVesuvio::simulate(const DetectorParams &detpar,
- const ResolutionParams &respar,
- MSVesuvioHelper::Simulation &simulCounts) const {
+void CalculateMSVesuvio::simulate(
+ const DetectorParams &detpar, const ResolutionParams &respar,
+ MSVesuvioHelper::Simulation &simulCounts) const {
for (size_t i = 0; i < m_nevents; ++i) {
calculateCounts(detpar, respar, simulCounts);
}
@@ -431,8 +432,7 @@ double CalculateMSVesuvio::calculateCounts(
V3D startPos(srcPos);
neutronDirs[0] = m_beamDir;
- generateScatter(startPos, neutronDirs[0], detpar.pos, weights[0],
- scatterPts[0]);
+ generateScatter(startPos, neutronDirs[0], weights[0], scatterPts[0]);
double distFromStart = startPos.distance(scatterPts[0]);
// Compute TOF for first scatter event
const double vel0 = sqrt(en1[0] / MASS_TO_MEV);
@@ -456,7 +456,7 @@ double CalculateMSVesuvio::calculateCounts(
// Update weight
const double wgt = weights[i];
- if (generateScatter(prevSc, newDir, detpar.pos, weights[i], curSc))
+ if (generateScatter(prevSc, newDir, weights[i], curSc))
break;
else {
weights[i] = wgt; // put it back to what it was
@@ -464,8 +464,9 @@ double CalculateMSVesuvio::calculateCounts(
}
} while (ntries < MAX_SCATTER_PT_TRIES);
if (ntries == MAX_SCATTER_PT_TRIES) {
- throw std::runtime_error(
- "Unable to generate scatter point in sample. Check sample shape.");
+ throw std::runtime_error("Cannot generate valid trajectory from within "
+ "the sample that intersects the sample. Does it "
+ "have a valid shape?");
}
const double scang = newDir.angle(oldDir);
@@ -602,16 +603,13 @@ double CalculateMSVesuvio::generateTOF(const double en0, const double dtof,
* amount the beam would be attenuted by the sample
* @param startPos Starting position
* @param direc Direction of travel for the neutron
- * @param detPos Position of the detector that the neutron will end up in. Used
- * to verify that the trajectory is actually possible from any generated scatter
- * point
- * @param weight [InOut] Multiply the incoming weight by the attenuation factor
+ * @param weight [InOut] Multiply the incoming weight by the attenuation
+ * factor
* @param scatterPt [Out] Generated scattering point
* @return True if the scatter event was generated, false otherwise
*/
bool CalculateMSVesuvio::generateScatter(const Kernel::V3D &startPos,
const Kernel::V3D &direc,
- const Kernel::V3D &detPos,
double &weight, V3D &scatterPt) const {
Track scatterTrack(startPos, direc);
if (m_sampleShape->interceptSurface(scatterTrack) != 1) {
@@ -630,15 +628,6 @@ bool CalculateMSVesuvio::generateScatter(const Kernel::V3D &startPos,
scatterPt = link->entryPoint;
V3D edgeDistances = (link->exitPoint - link->entryPoint);
scatterPt += edgeDistances * fraction;
-
- // Check that this point would for a valid track to the nominal detector
- // position
- V3D scToDet = detPos - scatterPt;
- scToDet.normalize();
- Geometry::Track scatterToDet(scatterPt, scToDet);
- if (m_sampleShape->interceptSurface(scatterToDet) != 1) {
- return false;
- }
// Update weight
weight *= scatterProb;
return true;
@@ -725,7 +714,8 @@ double CalculateMSVesuvio::partialDiffXSec(const double en0, const double en1,
* Generate a random position within the final detector in the lab frame
* @param nominalPos The poisiton of the centre point of the detector
* @param energy The final energy of the neutron
- * @param scatterPt The position of the scatter event that lead to this detector
+ * @param scatterPt The position of the scatter event that lead to this
+ * detector
* @param direcBeforeSc Directional vector that lead to scatter point that hit
* this detector
* @param scang [Output] The value of the scattering angle for the generated
@@ -737,12 +727,10 @@ double CalculateMSVesuvio::partialDiffXSec(const double en0, const double en1,
V3D CalculateMSVesuvio::generateDetectorPos(
const V3D &nominalPos, const double energy, const V3D &scatterPt,
const V3D &direcBeforeSc, double &scang, double &distToExit) const {
- const double mu =
- 7430.0 /
- sqrt(energy); // Inverse attenuation length (m-1) for vesuvio det.
- const double ps =
- 1.0 -
- exp(-mu * m_detThick); // Probability of detection in path thickness.
+ // Inverse attenuation length (m-1) for vesuvio det.
+ const double mu = 7430.0 / sqrt(energy);
+ // Probability of detection in path thickness.
+ const double ps = 1.0 - exp(-mu * m_detThick);
V3D detPos;
scang = 0.0;
distToExit = 0.0;
@@ -774,8 +762,10 @@ V3D CalculateMSVesuvio::generateDetectorPos(
++ntries;
} while (ntries < MAX_SCATTER_PT_TRIES);
if (ntries == MAX_SCATTER_PT_TRIES) {
- throw std::runtime_error("Unable to create track from sample to detector. "
- "Detector shape may be too small.");
+ // Assume it is very close to the surface so that the distance travelled
+ // would
+ // be a neglible contribution
+ distToExit = 0.0;
}
return detPos;
}