/// Calculate the distances traversed by the neutrons within the sample
/// @param detector :: The detector we are working on
/// @param L2s :: A vector of the sample-detector distance for each segment of
/// the sample
void AbsorptionCorrection::calculateDistances(const IDetector &detector,
std::vector<double> &L2s) const {
V3D detectorPos(detector.getPos());
if (detector.nDets() > 1) {
// We need to make sure this is right for grouped detectors - should use
// average theta & phi
detectorPos.spherical(detectorPos.norm(),
detector.getTwoTheta(V3D(), V3D(0, 0, 1)) * 180.0 /
M_PI,
detector.getPhi() * 180.0 / M_PI);
}
for (size_t i = 0; i < m_numVolumeElements; ++i) {
// Create track for distance in cylinder between scattering point and
// detector
V3D direction = detectorPos - m_elementPositions[i];
direction.normalize();
Track outgoing(m_elementPositions[i], direction);
int temp = m_sampleObject->interceptSurface(outgoing);
/* Most of the time, the number of hits is 1. Sometime, we have more than
* one intersection due to
* arithmetic imprecision. If it is the case, then selecting the first
* intersection is valid.
* In principle, one could check the consistency of all distances if hits is
* larger than one by doing:
* Mantid::Geometry::Track::LType::const_iterator it=outgoing.begin();
* and looping until outgoing.end() checking the distances with it->Dist
*/
// Not hitting the cylinder from inside, usually means detector is badly
// defined,
// i.e, position is (0,0,0).
if (temp < 1) {
// FOR NOW AT LEAST, JUST IGNORE THIS ERROR AND USE A ZERO PATH LENGTH,
// WHICH I RECKON WILL MAKE A
// NEGLIGIBLE DIFFERENCE ANYWAY (ALWAYS SEEMS TO HAPPEN WITH ELEMENT RIGHT
// AT EDGE OF SAMPLE)
L2s[i] = 0.0;
// std::ostringstream message;
// message << "Problem with detector at " << detectorPos << " ID:" <<
// detector->getID() << '\n';
// message << "This usually means that this detector is defined inside the
// sample cylinder";
// g_log.error(message.str());
// throw std::runtime_error("Problem in
// AbsorptionCorrection::calculateDistances");
} else // The normal situation
{
L2s[i] = outgoing.cbegin()->distFromStart;
}
}
}
/**
* @brief InstrumentVisitor::registerDetector
* @param detector : IDetector being visited
* @return Component index of this component
*/
size_t InstrumentVisitor::registerDetector(const IDetector &detector) {
auto detectorIndex = m_detectorIdToIndexMap->at(detector.getID());
/* Already allocated we just need to index into the inital front-detector
* part of the collection.
* 1. Guarantee on grouping detectors by type such that the first n
* components
* are detectors.
* 2. Guarantee on ordering such that the
* detectorIndex == componentIndex for all detectors.
*/
// Record the ID -> component index mapping
(*m_componentIdToIndexMap)[detector.getComponentID()] = detectorIndex;
(*m_componentIds)[detectorIndex] = detector.getComponentID();
m_assemblySortedDetectorIndices->push_back(detectorIndex);
(*m_detectorPositions)[detectorIndex] = Kernel::toVector3d(detector.getPos());
(*m_detectorRotations)[detectorIndex] =
Kernel::toQuaterniond(detector.getRotation());
(*m_shapes)[detectorIndex] = detector.shape();
(*m_scaleFactors)[detectorIndex] =
Kernel::toVector3d(detector.getScaleFactor());
if (m_instrument->isMonitorViaIndex(detectorIndex)) {
m_monitorIndices->push_back(detectorIndex);
}
(*m_names)[detectorIndex] = detector.getName();
clearLegacyParameters(m_pmap, detector);
/* Note that positions and rotations for detectors are currently
NOT stored! These go into DetectorInfo at present. push_back works for other
Component types because Detectors are always come first in the resultant
component list
forming a contiguous block.
*/
markAsSourceOrSample(detector.getComponentID(),
detectorIndex); // TODO. Optimisation. Cannot have a
// detector that is either source or
// sample. So delete this.
return detectorIndex;
}
