void TOFSANSResolutionByPixel::exec() {
MatrixWorkspace_sptr inOutWS = getProperty("Workspace");
double deltaR = getProperty("DeltaR");
double R1 = getProperty("SourceApertureRadius");
double R2 = getProperty("SampleApertureRadius");
// Convert to meters
deltaR /= 1000.0;
R1 /= 1000.0;
R2 /= 1000.0;
const MatrixWorkspace_sptr sigmaModeratorVSwavelength =
getProperty("SigmaModerator");
// create interpolation table from sigmaModeratorVSwavelength
Kernel::Interpolation lookUpTable;
const MantidVec xInterpolate = sigmaModeratorVSwavelength->readX(0);
const MantidVec yInterpolate = sigmaModeratorVSwavelength->readY(0);
// prefer the input to be a pointworkspace and create interpolation function
if (sigmaModeratorVSwavelength->isHistogramData()) {
g_log.notice() << "mid-points of SigmaModerator histogram bins will be "
"used for interpolation.";
for (size_t i = 0; i < xInterpolate.size() - 1; ++i) {
const double midpoint = xInterpolate[i + 1] - xInterpolate[i];
lookUpTable.addPoint(midpoint, yInterpolate[i]);
}
} else {
for (size_t i = 0; i < xInterpolate.size(); ++i) {
lookUpTable.addPoint(xInterpolate[i], yInterpolate[i]);
}
}
const V3D samplePos = inOutWS->getInstrument()->getSample()->getPos();
const V3D sourcePos = inOutWS->getInstrument()->getSource()->getPos();
const V3D SSD = samplePos - sourcePos;
const double L1 = SSD.norm();
const int numberOfSpectra = static_cast<int>(inOutWS->getNumberHistograms());
Progress progress(this, 0.0, 1.0, numberOfSpectra);
for (int i = 0; i < numberOfSpectra; i++) {
IDetector_const_sptr det;
try {
det = inOutWS->getDetector(i);
} catch (Exception::NotFoundError &) {
g_log.information() << "Spectrum index " << i
<< " has no detector assigned to it - discarding"
<< std::endl;
}
// If no detector found or if it's masked or a monitor, skip onto the next
// spectrum
if (!det || det->isMonitor() || det->isMasked())
continue;
// Get the flight path from the sample to the detector pixel
const V3D scatteredFlightPathV3D = det->getPos() - samplePos;
const double L2 = scatteredFlightPathV3D.norm();
const double Lsum = L1 + L2;
// calculate part that is wavelenght independent
const double dTheta2 = (4.0 * M_PI * M_PI / 12.0) *
(3.0 * R1 * R1 / (L1 * L1) +
3.0 * R2 * R2 * Lsum * Lsum / (L1 * L1 * L2 * L2) +
(deltaR * deltaR) / (L2 * L2));
// Multiplicative factor to go from lambda to Q
// Don't get fooled by the function name...
const double theta = inOutWS->detectorTwoTheta(det);
const double factor = 4.0 * M_PI * sin(theta / 2.0);
const MantidVec &xIn = inOutWS->readX(i);
MantidVec &yIn = inOutWS->dataY(i);
const size_t xLength = xIn.size();
// for each wavelenght bin of each pixel calculate a q-resolution
for (size_t j = 0; j < xLength - 1; j++) {
// use the midpoint of each bin
const double wl = (xIn[j + 1] + xIn[j]) / 2.0;
// Calculate q. Alternatively q could be calculated using ConvertUnit
const double q = factor / wl;
// wavelenght spread from bin assumed to be
const double sigmaSpreadFromBin = xIn[j + 1] - xIn[j];
// wavelenght spread from moderatorm, converted from microseconds to
// wavelengths
const double sigmaModerator =
lookUpTable.value(wl) * 3.9560 / (1000.0 * Lsum);
// calculate wavelenght resolution from moderator and histogram time bin
const double sigmaLambda =
std::sqrt(sigmaSpreadFromBin * sigmaSpreadFromBin / 12.0 +
sigmaModerator * sigmaModerator);
// calculate sigmaQ for a given lambda and pixel
const double sigmaOverLambdaTimesQ = q * sigmaLambda / wl;
const double sigmaQ = std::sqrt(
dTheta2 / (wl * wl) + sigmaOverLambdaTimesQ * sigmaOverLambdaTimesQ);
// update inout workspace with this sigmaQ
yIn[j] = sigmaQ;
}
progress.report("Computing Q resolution");
}
}
void TOFSANSResolutionByPixel::exec() {
MatrixWorkspace_sptr inWS = getProperty("InputWorkspace");
double deltaR = getProperty("DeltaR");
double R1 = getProperty("SourceApertureRadius");
double R2 = getProperty("SampleApertureRadius");
const bool doGravity = getProperty("AccountForGravity");
// Check the input
checkInput(inWS);
// Setup outputworkspace
auto outWS = setupOutputWorkspace(inWS);
// Convert to meters
deltaR /= 1000.0;
R1 /= 1000.0;
R2 /= 1000.0;
// The moderator workspace needs to match the data workspace
// in terms of wavelength binning
const MatrixWorkspace_sptr sigmaModeratorVSwavelength =
getModeratorWorkspace(inWS);
// create interpolation table from sigmaModeratorVSwavelength
Kernel::Interpolation lookUpTable;
const auto &xInterpolate = sigmaModeratorVSwavelength->points(0);
const auto &yInterpolate = sigmaModeratorVSwavelength->y(0);
// prefer the input to be a pointworkspace and create interpolation function
if (sigmaModeratorVSwavelength->isHistogramData()) {
g_log.notice() << "mid-points of SigmaModerator histogram bins will be "
"used for interpolation.";
}
for (size_t i = 0; i < xInterpolate.size(); ++i) {
lookUpTable.addPoint(xInterpolate[i], yInterpolate[i]);
}
// Calculate the L1 distance
const V3D samplePos = inWS->getInstrument()->getSample()->getPos();
const V3D sourcePos = inWS->getInstrument()->getSource()->getPos();
const V3D SSD = samplePos - sourcePos;
const double L1 = SSD.norm();
// Get the collimation length
double LCollim = getProperty("CollimationLength");
if (LCollim == 0.0) {
auto collimationLengthEstimator = SANSCollimationLengthEstimator();
LCollim = collimationLengthEstimator.provideCollimationLength(inWS);
g_log.information() << "No collimation length was specified. A default "
"collimation length was estimated to be " << LCollim
<< '\n';
} else {
g_log.information() << "The collimation length is " << LCollim << '\n';
}
const int numberOfSpectra = static_cast<int>(inWS->getNumberHistograms());
Progress progress(this, 0.0, 1.0, numberOfSpectra);
const auto &spectrumInfo = inWS->spectrumInfo();
for (int i = 0; i < numberOfSpectra; i++) {
IDetector_const_sptr det;
if (!spectrumInfo.hasDetectors(i)) {
g_log.information() << "Workspace index " << i
<< " has no detector assigned to it - discarding\n";
continue;
}
// If no detector found or if it's masked or a monitor, skip onto the next
// spectrum
if (spectrumInfo.isMonitor(i) || spectrumInfo.isMasked(i))
continue;
const double L2 = spectrumInfo.l2(i);
TOFSANSResolutionByPixelCalculator calculator;
const double waveLengthIndependentFactor =
calculator.getWavelengthIndependentFactor(R1, R2, deltaR, LCollim, L2);
// Multiplicative factor to go from lambda to Q
// Don't get fooled by the function name...
const double theta = spectrumInfo.twoTheta(i);
double sinTheta = sin(0.5 * theta);
double factor = 4.0 * M_PI * sinTheta;
const auto &xIn = inWS->x(i);
const size_t xLength = xIn.size();
// Gravity correction
std::unique_ptr<GravitySANSHelper> grav;
if (doGravity) {
grav = Kernel::make_unique<GravitySANSHelper>(spectrumInfo, i,
getProperty("ExtraLength"));
}
// Get handles on the outputWorkspace
auto &yOut = outWS->mutableY(i);
// for each wavelenght bin of each pixel calculate a q-resolution
for (size_t j = 0; j < xLength - 1; j++) {
// use the midpoint of each bin
const double wl = (xIn[j + 1] + xIn[j]) / 2.0;
// Calculate q. Alternatively q could be calculated using ConvertUnit
// If we include a gravity correction we need to adjust sinTheta
// for each wavelength (in Angstrom)
if (doGravity) {
double sinThetaGrav = grav->calcSinTheta(wl);
factor = 4.0 * M_PI * sinThetaGrav;
}
const double q = factor / wl;
// wavelenght spread from bin assumed to be
const double sigmaSpreadFromBin = xIn[j + 1] - xIn[j];
// Get the uncertainty in Q
auto sigmaQ = calculator.getSigmaQValue(lookUpTable.value(wl),
waveLengthIndependentFactor, q,
wl, sigmaSpreadFromBin, L1, L2);
// Insert the Q value and the Q resolution into the outputworkspace
yOut[j] = sigmaQ;
}
progress.report("Computing Q resolution");
}
// Set the y axis label
outWS->setYUnitLabel("QResolution");
setProperty("OutputWorkspace", outWS);
}
