| 1 | """*WIKI* |
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| 2 | |
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| 3 | Calculates the scattering & transmission for Indirect Geometry spectrometers. The sample chemical formula is input for the SetSampleMaterial algorithm to calculate the cross-sections. |
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| 4 | The instrument analyser reflection is selected to obtain the wavelength to calculate the absorption cross-section. The sample number density & thickness is input to then calculate the percentage scattering & transmission. |
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| 5 | |
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| 6 | *WIKI*""" |
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| 7 | |
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| 8 | from mantid.simpleapi import * |
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| 9 | from mantid.api import PythonAlgorithm, AlgorithmFactory |
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| 10 | from mantid.kernel import StringListValidator, StringMandatoryValidator |
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| 11 | from mantid import config |
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| 12 | from IndirectCommon import StartTime, EndTime |
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| 13 | import os.path, math |
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| 14 | |
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| 15 | class IndirectTransmission(PythonAlgorithm): |
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| 16 | |
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| 17 | def category(self): |
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| 18 | return "Workflow\\MIDAS;PythonAlgorithms" |
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| 19 | |
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| 20 | def PyInit(self): |
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| 21 | self.declareProperty(name='Instrument',defaultValue='IRIS',validator=StringListValidator(['IRIS','OSIRIS']), doc='Instrument') |
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| 22 | self.declareProperty(name='Analyser',defaultValue='graphite',validator=StringListValidator(['graphite','fmica']), doc='Analyser') |
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| 23 | self.declareProperty(name='Reflection',defaultValue='002',validator=StringListValidator(['002','004']), doc='Reflection') |
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| 24 | self.declareProperty(name='Chemical Formula',defaultValue='',validator=StringMandatoryValidator(), doc='Sample chemical formula') |
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| 25 | self.declareProperty(name='Number Density', defaultValue=0.1, doc='Number denisty. Default=0.1') |
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| 26 | self.declareProperty(name='Thickness', defaultValue=0.1, doc='Sample thickness. Default=0.1') |
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| 27 | |
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| 28 | def PyExec(self): |
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| 29 | |
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| 30 | StartTime('IndirectTransmission') |
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| 31 | |
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| 32 | instrumentName = self.getPropertyValue('Instrument') |
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| 33 | analyser = self.getPropertyValue('Analyser') |
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| 34 | reflection = self.getPropertyValue('Reflection') |
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| 35 | formula = self.getPropertyValue('Chemical Formula') |
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| 36 | density = self.getPropertyValue('Number Density') |
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| 37 | thickness = self.getPropertyValue('Thickness') |
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| 38 | |
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| 39 | #Load instrument defintion file |
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| 40 | idfDir = config['instrumentDefinition.directory'] |
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| 41 | idf = idfDir + instrumentName + '_Definition.xml' |
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| 42 | workspace = '__empty_'+instrumentName |
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| 43 | LoadEmptyInstrument(OutputWorkspace=workspace, Filename=idf) |
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| 44 | |
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| 45 | #Load instrument parameter file |
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| 46 | nameStem = instrumentName + '_' + analyser + '_' + reflection |
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| 47 | ipf = idfDir + nameStem + '_Parameters.xml' |
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| 48 | LoadParameterFile(Workspace=workspace, Filename=ipf) |
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| 49 | |
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| 50 | #Get efixed value |
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| 51 | instrument = mtd[workspace].getInstrument() |
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| 52 | efixed = instrument.getNumberParameter('efixed-val')[0] |
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| 53 | |
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| 54 | logger.notice('Analyser : ' +analyser+reflection +' with energy = ' + str(efixed)) |
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| 55 | |
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| 56 | result = SetSampleMaterial(InputWorkspace=workspace,ChemicalFormula=formula) |
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| 57 | |
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| 58 | #elastic wavelength |
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| 59 | wave=1.8*math.sqrt(25.2429/efixed) |
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| 60 | |
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| 61 | absorptionXSection = result[5]*wave/1.7982 |
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| 62 | coherentXSection = result[4] |
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| 63 | incoherentXSection = result[3] |
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| 64 | scatteringXSection = result[3] |
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| 65 | |
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| 66 | thickness = float(thickness) |
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| 67 | density = float(density) |
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| 68 | |
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| 69 | totalXSection = absorptionXSection + scatteringXSection |
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| 70 | |
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| 71 | transmission = math.exp(-density*totalXSection*thickness) |
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| 72 | scattering = 1.0 - math.exp(-density*scatteringXSection*thickness) |
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| 73 | |
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| 74 | #Create table workspace to store calculations |
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| 75 | tableWs = nameStem + '_Transmission' |
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| 76 | tableWs = CreateEmptyTableWorkspace(OutputWorkspace=tableWs) |
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| 77 | tableWs.addColumn("str", "Name") |
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| 78 | tableWs.addColumn("str", "Value") |
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| 79 | |
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| 80 | #Add values to table workspace |
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| 81 | tableWs.addRow(['Absorption Xsection at wavelength ', str(wave) + |
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| 82 | ' A = '+str(absorptionXSection)]) |
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| 83 | tableWs.addRow(['Coherent Xsection', str(coherentXSection)]) |
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| 84 | tableWs.addRow(['Incoherent Xsection', str(incoherentXSection)]) |
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| 85 | tableWs.addRow(['Total scattering Xsection', str(scatteringXSection)]) |
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| 86 | tableWs.addRow(['Number density', str(density)]) |
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| 87 | tableWs.addRow(['Thickness', str(thickness)]) |
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| 88 | tableWs.addRow(['Transmission (abs+scatt)', str(transmission)]) |
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| 89 | tableWs.addRow(['Total scattering', str(scattering)]) |
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| 90 | |
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| 91 | #Output values to the results log |
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| 92 | logger.notice('Absorption Xsection at wavelength ' + str(wave) + |
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| 93 | ' A = '+str(absorptionXSection)) |
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| 94 | logger.notice('Coherent Xsection = '+ str(coherentXSection)) |
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| 95 | logger.notice('Incoherent Xsection = ' + str(incoherentXSection)) |
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| 96 | logger.notice('Total scattering Xsection = ' + str(scatteringXSection)) |
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| 97 | logger.notice('Number density = ' + str(density)) |
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| 98 | logger.notice('Thickness = ' + str(thickness)) |
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| 99 | logger.notice('Transmission (abs+scatt) = ' +str(transmission)) |
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| 100 | logger.notice('Total scattering = ' +str(scattering)) |
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| 101 | |
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| 102 | #remove idf/ipf workspace |
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| 103 | DeleteWorkspace(workspace) |
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| 104 | |
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| 105 | EndTime('IndirectTransmission') |
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| 106 | |
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| 107 | # Register algorithm with Mantid |
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| 108 | AlgorithmFactory.subscribe(IndirectTransmission) |
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