diff --git a/Framework/Kernel/inc/MantidKernel/AttenuationProfile.h b/Framework/Kernel/inc/MantidKernel/AttenuationProfile.h
index 32b8817f2db04825255fff883de249de7798ce92..c210af1a6239f843e437a11cdf5206a817022afb 100644
--- a/Framework/Kernel/inc/MantidKernel/AttenuationProfile.h
+++ b/Framework/Kernel/inc/MantidKernel/AttenuationProfile.h
@@ -1,8 +1,8 @@
// Mantid Repository : https://github.com/mantidproject/mantid
//
// Copyright © 2020 ISIS Rutherford Appleton Laboratory UKRI,
-// NScD Oak Ridge National Laboratory, European Spallation Source
-// & Institut Laue - Langevin
+// NScD Oak Ridge National Laboratory, European Spallation Source,
+// Institut Laue - Langevin & CSNS, Institute of High Energy Physics, CAS
// SPDX - License - Identifier: GPL - 3.0 +
#pragma once
@@ -13,10 +13,13 @@
namespace Mantid {
namespace Kernel {
+class Material;
+
class MANTID_KERNEL_DLL AttenuationProfile {
public:
AttenuationProfile(const std::string &inputFileName,
- const std::string &searchPath);
+ const std::string &searchPath,
+ Material *extrapolationMaterial = nullptr);
double getAttenuationCoefficient(const double lambda) const;
private:
diff --git a/Framework/Kernel/inc/MantidKernel/Material.h b/Framework/Kernel/inc/MantidKernel/Material.h
index 2f9743934cc6bc894a91e0a934223ff10be1de3d..14fc204534889525897fb5fc4f458a8eeda6d15f 100644
--- a/Framework/Kernel/inc/MantidKernel/Material.h
+++ b/Framework/Kernel/inc/MantidKernel/Material.h
@@ -30,6 +30,8 @@ class Atom;
namespace Kernel {
+class AttenuationProfile;
+
/**
A material is defined as being composed of a given element, defined as a
PhysicalConstants::NeutronAtom, with the following properties:
@@ -104,6 +106,7 @@ public:
double
absorbXSection(const double lambda =
PhysicalConstants::NeutronAtom::ReferenceLambda) const;
+ double attenuationCoefficient(const double lambda) const;
/// Compute the attenuation at a given wavelength over the given distance
double attenuation(const double distance,
const double lambda =
diff --git a/Framework/Kernel/src/AttenuationProfile.cpp b/Framework/Kernel/src/AttenuationProfile.cpp
index 555f10817d5ffffcdf23f45ce949f117bd0a244e..684dadd5e70f61fa95ea6930d7bb391488d41c67 100644
--- a/Framework/Kernel/src/AttenuationProfile.cpp
+++ b/Framework/Kernel/src/AttenuationProfile.cpp
@@ -1,12 +1,13 @@
// Mantid Repository : https://github.com/mantidproject/mantid
//
// Copyright © 2020 ISIS Rutherford Appleton Laboratory UKRI,
-// NScD Oak Ridge National Laboratory, European Spallation Source
-// & Institut Laue - Langevin
+// NScD Oak Ridge National Laboratory, European Spallation Source,
+// Institut Laue - Langevin & CSNS, Institute of High Energy Physics, CAS
// SPDX - License - Identifier: GPL - 3.0 +
#include "MantidKernel/AttenuationProfile.h"
#include "MantidKernel/ConfigService.h"
#include "MantidKernel/Exception.h"
+#include "MantidKernel/Material.h"
#include <Poco/File.h>
#include <Poco/Path.h>
#include <fstream>
@@ -14,14 +15,22 @@
namespace Mantid {
namespace Kernel {
+namespace {
+constexpr auto LARGE_LAMBDA = 100; // Lambda likely to be beyond max lambda in
+ // any measured spectra. In Angstroms
+}
+
/**
* Construct an attenuation profile object
* @param inputFileName :: The name of the file containing the attenuation
* profile data. Filename can be a full path or just file name
* @param searchPath :: Path to search for the input file
+ * @param extrapolationMaterial :: Material whose properties will be used to
+ * extrapolate beyond the lambda range of the supplied profile
*/
AttenuationProfile::AttenuationProfile(const std::string &inputFileName,
- const std::string &searchPath) {
+ const std::string &searchPath,
+ Material *extrapolationMaterial) {
Poco::Path suppliedFileName(inputFileName);
Poco::Path inputFilePath;
std::string fileExt = suppliedFileName.getExtension();
@@ -55,13 +64,33 @@ AttenuationProfile::AttenuationProfile(const std::string &inputFileName,
std::ifstream input(inputFilePath.toString(), std::ios_base::in);
if (input) {
std::string line;
+ double minLambda = std::numeric_limits<double>::max();
+ double maxLambda = std::numeric_limits<double>::min();
while (std::getline(input, line)) {
double lambda, alpha, error;
if (std::stringstream(line) >> lambda >> alpha >> error) {
+ minLambda = std::min(lambda, minLambda);
+ maxLambda = std::max(lambda, maxLambda);
m_Interpolator.addPoint(lambda, 1000 * alpha);
}
}
input.close();
+ // Assist the extrapolation outside the supplied lambda range to better
+ // handle noisy data. Add two surrounding points using the attenuation
+ // calculated from tabulated absorption\scattering cross sections
+ if (m_Interpolator.containData() && extrapolationMaterial) {
+ if ((minLambda > 0) &&
+ (minLambda < std::numeric_limits<double>::max())) {
+ m_Interpolator.addPoint(
+ 0, extrapolationMaterial->attenuationCoefficient(0));
+ }
+ if ((maxLambda < LARGE_LAMBDA) &&
+ (maxLambda > std::numeric_limits<double>::min())) {
+ m_Interpolator.addPoint(
+ LARGE_LAMBDA,
+ extrapolationMaterial->attenuationCoefficient(LARGE_LAMBDA));
+ }
+ }
} else {
throw Exception::FileError("Error reading attenuation profile file",
inputFileName);
diff --git a/Framework/Kernel/src/Material.cpp b/Framework/Kernel/src/Material.cpp
index 2fa8026842b48675e20e8babb270e908ab121b31..c7ea55ee5c9115f2d170257764312617930d86c1 100644
--- a/Framework/Kernel/src/Material.cpp
+++ b/Framework/Kernel/src/Material.cpp
@@ -6,6 +6,7 @@
// SPDX - License - Identifier: GPL - 3.0 +
#include "MantidKernel/Material.h"
#include "MantidKernel/Atom.h"
+#include "MantidKernel/AttenuationProfile.h"
#include "MantidKernel/StringTokenizer.h"
#include <NeXusFile.hpp>
#include <boost/lexical_cast.hpp>
@@ -255,21 +256,29 @@ double Material::absorbXSection(const double lambda) const {
}
/**
- * @param distance Distance (m) travelled
* @param lambda Wavelength (Angstroms) to compute the attenuation (default =
* reference lambda)
- * @return The dimensionless attenuation coefficient
+ * @return The attenuation coefficient in m-1
*/
-double Material::attenuation(const double distance, const double lambda) const {
+double Material::attenuationCoefficient(const double lambda) const {
if (!m_attenuationOverride) {
- return exp(-100 * numberDensity() *
- (totalScatterXSection() + absorbXSection(lambda)) * distance);
+ return 100 * numberDensity() *
+ (totalScatterXSection() + absorbXSection(lambda));
} else {
- return exp(-m_attenuationOverride->getAttenuationCoefficient(lambda) *
- distance);
+ return m_attenuationOverride->getAttenuationCoefficient(lambda);
}
}
+/**
+ * @param distance Distance (m) travelled
+ * @param lambda Wavelength (Angstroms) to compute the attenuation (default =
+ * reference lambda)
+ * @return The dimensionless attenuation factor
+ */
+double Material::attenuation(const double distance, const double lambda) const {
+ return exp(-attenuationCoefficient(lambda) * distance);
+}
+
// NOTE: the angstrom^-2 to barns and the angstrom^-1 to cm^-1
// will cancel for mu to give units: cm^-1
double Material::linearAbsorpCoef(const double lambda) const {
diff --git a/Framework/Kernel/src/MaterialBuilder.cpp b/Framework/Kernel/src/MaterialBuilder.cpp
index 690a0ca70346aee7b6a7b4485fe297ed0156c331..b4bc69ce1e671f6e068f2b8eb7ac464cff33caeb 100644
--- a/Framework/Kernel/src/MaterialBuilder.cpp
+++ b/Framework/Kernel/src/MaterialBuilder.cpp
@@ -259,7 +259,8 @@ Material MaterialBuilder::build() const {
}
if (m_attenuationProfileFileName) {
AttenuationProfile materialAttenuation(m_attenuationProfileFileName.get(),
- m_attenuationFileSearchPath);
+ m_attenuationFileSearchPath,
+ material.get());
material->setAttenuationProfile(materialAttenuation);
}
return *material;
diff --git a/Framework/Kernel/test/AttenuationProfileTest.h b/Framework/Kernel/test/AttenuationProfileTest.h
index 05d4ad8598048c64d6fc4eb0e0b940e3837d8b78..863873e94c510f9093fc6a1a061e1ce455c31d72 100644
--- a/Framework/Kernel/test/AttenuationProfileTest.h
+++ b/Framework/Kernel/test/AttenuationProfileTest.h
@@ -1,14 +1,15 @@
// Mantid Repository : https://github.com/mantidproject/mantid
//
// Copyright © 2020 ISIS Rutherford Appleton Laboratory UKRI,
-// NScD Oak Ridge National Laboratory, European Spallation Source
-// & Institut Laue - Langevin
+// NScD Oak Ridge National Laboratory, European Spallation Source,
+// Institut Laue - Langevin & CSNS, Institute of High Energy Physics, CAS
// SPDX - License - Identifier: GPL - 3.0 +
#pragma once
#include "MantidKernel/AttenuationProfile.h"
#include "MantidKernel/ConfigService.h"
#include "MantidKernel/Exception.h"
+#include "MantidKernel/Material.h"
#include <ctime>
#include <cxxtest/TestSuite.h>
@@ -27,21 +28,38 @@ public:
void testLoadAttenuationFile() {
std::string path = Mantid::Kernel::ConfigService::Instance().getFullPath(
"AttenuationProfile.DAT", false, 0);
- TS_ASSERT_THROWS_NOTHING(auto loader = AttenuationProfile(path, ""));
+ TS_ASSERT_THROWS_NOTHING(auto profile = AttenuationProfile(path, ""));
}
void testLoadInvalidAttenuationFile() {
std::string path = Mantid::Kernel::ConfigService::Instance().getFullPath(
"INVALID.DAT", false, 0);
- TS_ASSERT_THROWS(auto loader = AttenuationProfile(path, ""),
+ TS_ASSERT_THROWS(auto profile = AttenuationProfile(path, ""),
Mantid::Kernel::Exception::FileError &);
}
void testGetAttenuationCoefficient() {
std::string path = Mantid::Kernel::ConfigService::Instance().getFullPath(
"AttenuationProfile.DAT", false, 0);
- auto loader = AttenuationProfile(path, "");
- TS_ASSERT_EQUALS(loader.getAttenuationCoefficient(0.10027009),
+ auto profile = AttenuationProfile(path, "");
+ TS_ASSERT_EQUALS(profile.getAttenuationCoefficient(0.10027009),
1000 * 0.82631156E-01);
}
+
+ void testGetAttenuationCoefficientBeyondRange() {
+ Material::ChemicalFormula formula;
+ formula = Material::parseChemicalFormula("C");
+ auto testMaterial =
+ std::make_unique<Material>("test", formula, 3.51); // diamond
+ std::string path = Mantid::Kernel::ConfigService::Instance().getFullPath(
+ "AttenuationProfile.DAT", false, 0);
+ auto profile = AttenuationProfile(path, "", testMaterial.get());
+ auto profileWithEmptyMaterial = AttenuationProfile(path, "");
+ TS_ASSERT_EQUALS(profile.getAttenuationCoefficient(0),
+ testMaterial->attenuationCoefficient(0));
+ // double check the supplied attenuation profile didn't happen to have
+ // a value at zero matching the coefficient from the material
+ TS_ASSERT_DIFFERS(profileWithEmptyMaterial.getAttenuationCoefficient(0),
+ testMaterial->attenuationCoefficient(0));
+ }
};