1 | #pragma rtGlobals=1 // Use modern global access method. |
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2 | #pragma version=5.0 |
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3 | #pragma IgorVersion = 7.00 |
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4 | |
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5 | |
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6 | // |
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7 | // resolution calculations for VSANS, under a variety of collimation conditions |
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8 | // |
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9 | // Partially converted (July 2017) |
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10 | // |
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11 | // |
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12 | // -- still missing a lot of physical dimensions for the SANS (1D) case |
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13 | // let alone anything more complex |
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14 | // |
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15 | // |
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16 | // SANS-like (pinhole) conditions are largely copied from the SANS calcuations |
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17 | // and are the traditional extra three columns |
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18 | // |
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19 | // Other conditions, such as white beam, or narrow slit mode, will likely require some |
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20 | // format for the resolution information that is different than the three column format. |
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21 | // The USANS solution of a "flag" is clunky, and depends entirely on the analysis package to |
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22 | // know exactly what to do. |
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23 | // |
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24 | // the 2D SANS-like resolution calculation is also expected to be similar to SANS, but is |
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25 | // unverified at this point (July 2017). 2D errors are also unverified. |
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26 | // -- Most importantly for 2D VSANS data, there is no defined output format. |
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27 | // |
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28 | |
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29 | |
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30 | // TODO: |
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31 | // -- some of the input geometry is hidden in other locations: |
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32 | // Sample Aperture to Gate Valve (cm) == /instrument/sample_aperture/distance |
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33 | // Sample [position] to Gate Valve (cm) = /instrument/sample_table/offset_distance |
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34 | // |
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35 | // -- the dimensions and the units for the beam stops are very odd, and what is written to the |
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36 | // file is not what is noted in the GUI - so verify the units that I'm actually reading. |
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37 | // |
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38 | |
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39 | |
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40 | |
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41 | |
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42 | //********************** |
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43 | // Resolution calculation - used by the averaging routines |
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44 | // to calculate the resolution function at each q-value |
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45 | // - the return value is not used |
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46 | // |
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47 | // equivalent to John's routine on the VAX Q_SIGMA_AVE.FOR |
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48 | // Incorporates eqn. 3-15 from J. Appl. Cryst. (1995) v. 28 p105-114 |
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49 | // |
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50 | // - 21 MAR 07 uses projected BS diameter on the detector |
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51 | // - APR 07 still need to add resolution with lenses. currently there is no flag in the |
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52 | // raw data header to indicate the presence of lenses. |
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53 | // |
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54 | // - Aug 07 - added input to switch calculation based on lenses (==1 if in) |
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55 | // |
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56 | // - SANS -- called by CircSectAvg.ipf and RectAnnulAvg.ipf |
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57 | // |
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58 | // - VSANS -- called in VC_fDoBinning_QxQy2D(folderStr, binningType) |
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59 | // |
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60 | // DDet is the detector pixel resolution |
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61 | // apOff is the offset between the sample aperture and the sample position |
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62 | // |
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63 | // |
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64 | // INPUT: |
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65 | // inQ = q-value [1/A] |
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66 | // folderStr = folder with the current reduction step |
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67 | // type = binning type (not the same as the detStr) |
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68 | // collimationStr = collimation type, to switch for lenses, etc. |
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69 | |
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70 | // READ/DERIVED within the function |
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71 | // lambda = wavelength [A] |
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72 | // lambdaWidth = [dimensionless] |
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73 | // DDet = detector pixel resolution [cm] **assumes square pixel |
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74 | // apOff = sample aperture to sample distance [cm] |
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75 | // S1 = source aperture diameter [mm] |
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76 | // S2 = sample aperture diameter [mm] |
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77 | // L1 = source to sample distance [m] |
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78 | // L2 = sample to detector distance [m] |
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79 | // BS = beam stop diameter [mm] |
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80 | // del_r = step size [mm] = binWidth*(mm/pixel) |
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81 | // usingLenses = flag for lenses = 0 if no lenses, non-zero if lenses are in-beam |
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82 | // |
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83 | // OUPUT: |
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84 | // SigmaQ |
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85 | // QBar |
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86 | // fSubS |
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87 | // |
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88 | // |
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89 | Function V_getResolution(inQ,folderStr,type,collimationStr,SigmaQ,QBar,fSubS) |
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90 | Variable inQ |
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91 | String folderStr,type,collimationStr |
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92 | Variable &SigmaQ, &QBar, &fSubS //these are the output quantities at the input Q value |
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93 | |
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94 | Variable isVCALC |
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95 | if(cmpstr(folderStr,"VCALC") == 0) |
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96 | isVCALC = 1 |
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97 | endif |
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98 | |
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99 | Variable lambda,lambdaWidth,DDet,apOff,S1,S2,L1,L2,BS,del_r,usingLenses |
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100 | |
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101 | //lots of calculation variables |
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102 | Variable a2, q_small, lp, v_lambda, v_b, v_d, vz, yg, v_g |
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103 | Variable r0, delta, inc_gamma, fr, fv, rmd, v_r1, rm, v_r |
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104 | |
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105 | //Constants |
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106 | Variable vz_1 = 3.956e5 //velocity [cm/s] of 1 A neutron |
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107 | Variable g = 981.0 //gravity acceleration [cm/s^2] |
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108 | |
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109 | ///////// get all of the values from the header |
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110 | // TODO: check the units of all of the inputs |
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111 | // lambda = wavelength [A] |
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112 | if(isVCALC) |
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113 | lambda = VCALC_getWavelength() |
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114 | else |
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115 | lambda = V_getWavelength(folderStr) |
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116 | endif |
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117 | |
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118 | // lambdaWidth = [dimensionless] |
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119 | if(isVCALC) |
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120 | lambdaWidth = VCALC_getWavelengthSpread() |
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121 | else |
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122 | lambdaWidth = V_getWavelength_spread(folderStr) |
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123 | endif |
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124 | |
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125 | // DDet = detector pixel resolution [cm] **assumes square pixel |
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126 | // V_getDet_pixel_fwhm_x(folderStr,detStr) |
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127 | // V_getDet_pixel_fwhm_y(folderStr,detStr) |
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128 | // DDet = 0.8 // TODO -- this is hard-wired |
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129 | |
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130 | if(isVCALC) |
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131 | if(strlen(type) == 1) |
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132 | // it's "B" |
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133 | DDet = VCALC_getPixSizeX(type) // value is already in cm |
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134 | else |
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135 | DDet = VCALC_getPixSizeX(type[0,1]) // value is already in cm |
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136 | endif |
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137 | else |
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138 | if(strlen(type) == 1) |
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139 | // it's "B" |
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140 | DDet = V_getDet_pixel_fwhm_x(folderStr,type) // value is already in cm |
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141 | else |
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142 | DDet = V_getDet_pixel_fwhm_x(folderStr,type[0,1]) // value is already in cm |
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143 | endif |
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144 | endif |
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145 | // apOff = sample aperture to sample distance [cm] |
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146 | apOff = 10 // TODO -- this is hard-wired |
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147 | |
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148 | |
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149 | // S1 = source aperture diameter [mm] |
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150 | // may be either circle or rectangle |
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151 | String s1_shape="",bs_shape="" |
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152 | Variable width,height,equiv_S1,equiv_bs |
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153 | |
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154 | if(isVCALC) |
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155 | S1 = VC_sourceApertureDiam()*10 //VCALC is in cm, conver to [mm] |
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156 | else |
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157 | s1_shape = V_getSourceAp_shape(folderStr) |
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158 | if(cmpstr(s1_shape,"CIRCLE") == 0) |
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159 | S1 = str2num(V_getSourceAp_size(folderStr)) |
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160 | else |
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161 | S1 = V_getSourceAp_height(folderStr) // TODO: need the width or at least an equivalent diameter |
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162 | endif |
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163 | endif |
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164 | |
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165 | // S2 = sample aperture diameter [cm] |
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166 | // as of 3/2018, the "internal" sample aperture is not in use, only the external |
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167 | // TODO : verify the units on the Ap2 (external) |
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168 | // sample aperture 1(internal) is set to report "12.7 mm" as a STRING |
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169 | // sample aperture 2(external) reports the number typed in... |
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170 | // |
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171 | if(isVCALC) |
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172 | S2 = VC_sampleApertureDiam()*10 // convert cm to mm |
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173 | else |
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174 | // I'm trusting [cm] is in the RAW data file, or returned from the function if the date is prior to 5/22/19 |
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175 | S2 = V_getSampleAp2_size(folderStr)*10 // sample ap 1 or 2? 2 = the "external", convert to [mm] |
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176 | endif |
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177 | |
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178 | // L1 = source Ap to sample Ap distance [m] |
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179 | if(isVCALC) |
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180 | L1 = VC_calcSSD()/100 //convert cm to m |
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181 | else |
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182 | L1 = V_getSourceAp_distance(folderStr)/100 |
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183 | endif |
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184 | |
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185 | // L2 = sample aperture to detector distance [m] |
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186 | // take the first two characters of the "type" to get the correct distance. |
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187 | // if the type is say, MLRTB, then the implicit assumption in combining all four panels is that the resolution |
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188 | // is not an issue for the slightly different distances. |
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189 | if(isVCALC) |
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190 | if(strlen(type) == 1) |
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191 | // it's "B" |
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192 | L2 = VC_calc_L2(type)/100 //convert cm to m |
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193 | else |
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194 | L2 = VC_calc_L2(type[0,1])/100 //convert cm to m |
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195 | endif |
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196 | else |
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197 | if(strlen(type) == 1) |
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198 | // it's "B" |
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199 | L2 = V_getDet_ActualDistance(folderStr,type)/100 //convert cm to m |
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200 | else |
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201 | L2 = V_getDet_ActualDistance(folderStr,type[0,1])/100 //convert cm to m |
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202 | endif |
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203 | endif |
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204 | |
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205 | |
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206 | // BS = beam stop diameter [mm] |
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207 | //TODO:? which BS is in? carr2, carr3, none? |
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208 | // -- need to check the detector, num_beamstops field, then description, then shape/size or shape/height and shape/width |
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209 | // |
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210 | |
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211 | if(isVCALC) |
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212 | BS = VC_beamstopDiam(type[0,1])*10 // convert cm to mm |
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213 | else |
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214 | BS = V_IdentifyBeamstopDiameter(folderStr,type) //returns diameter in [mm] |
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215 | endif |
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216 | // BS = V_getBeamStopC2_size(folderStr) // Units are [mm] |
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217 | // BS = 25.4 //TODO hard-wired value |
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218 | |
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219 | // bs_shape = V_getBeamStopC2_shape(folderStr) |
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220 | // if(cmpstr(s1_shape,"CIRCLE") == 0) |
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221 | // bs = V_getBeamStopC2_size(folderStr) |
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222 | // else |
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223 | // bs = V_getBeamStopC2_height(folderStr) |
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224 | // endif |
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225 | |
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226 | |
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227 | |
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228 | // del_r = step size [mm] = binWidth*(mm/pixel) |
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229 | del_r = 1*DDet*10 // TODO: this is probably not the correct value |
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230 | |
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231 | // usingLenses = flag for lenses = 0 if no lenses, non-zero if lenses are in-beam |
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232 | usingLenses = 0 |
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233 | |
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234 | //if(cmpstr(type[0,1],"FL")==0) |
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235 | // Print "(FL) Resolution lambda,lambdaWidth,DDet,apOff,S1,S2,L1,L2,BS,del_r,usingLenses" |
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236 | // Print lambda,lambdaWidth,DDet,apOff,S1,S2,L1,L2,BS,del_r,usingLenses |
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237 | //endif |
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238 | |
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239 | |
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240 | |
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241 | // TODO: |
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242 | // this is the point where I need to switch on the different collimation types (white beam, slit, Xtal, etc) |
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243 | // to calculate the correct resolution, or fill the waves with the correct "flags" |
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244 | // |
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245 | |
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246 | // For white beam data, the wavelength distribution can't be represented as a gaussian, but all of the other |
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247 | // geometric corrections still apply. Passing zero for the lambdaWidth will return the geometry contribution, |
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248 | // as long as the wavelength can be handled separately. It appears to be correct to do as a double integral, |
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249 | // with the inner(lambda) calculated first, then the outer(geometry). |
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250 | // |
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251 | |
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252 | // possible values are: |
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253 | // |
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254 | // pinhole |
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255 | // pinhole_whiteBeam |
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256 | // convergingPinholes |
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257 | // |
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258 | // *slit data should be reduced using the slit routine, not here, proceed but warn |
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259 | // narrowSlit |
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260 | // narrowSlit_whiteBeam |
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261 | |
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262 | // TODO: this is a messy way to identify the super white beam condition, and it needs to be |
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263 | // done in a cleaner fashion (through IdentityCollimation) once NICE catches up |
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264 | |
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265 | // String monoType = V_IdentifyMonochromatorType(folderStr) |
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266 | |
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267 | |
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268 | if(cmpstr(collimationStr,"pinhole_super_white_beam")==0) |
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269 | lambdaWidth = 0 |
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270 | endif |
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271 | |
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272 | if(cmpstr(collimationStr,"pinhole_whiteBeam") == 0) |
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273 | // set lambdaWidth == 0 so that the gaussian resolution calculates only the geometry contribution. |
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274 | // the white beam distribution will need to be flagged some other way |
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275 | // |
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276 | lambdaWidth = 0 |
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277 | endif |
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278 | |
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279 | if(cmpstr(collimationStr,"convergingPinholes") == 0) |
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280 | |
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281 | // set usingLenses == 1 so that the Gaussian resolution calculation will be for a focus condition |
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282 | usingLenses = 1 |
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283 | endif |
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284 | |
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285 | |
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286 | // should not end up here, except for odd testing cases |
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287 | if(cmpstr(collimationStr,"narrowSlit") == 0) |
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288 | |
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289 | Print "??? Slit data is being averaged as pinhole - reset the AVERAGE parameters in the protocol ???" |
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290 | endif |
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291 | |
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292 | // should not end up here, except for odd testing cases |
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293 | if(cmpstr(collimationStr,"narrowSlit_whiteBeam") == 0) |
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294 | |
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295 | // set lambdaWidth == 0 so that the gaussian resolution calculates only the geometry contribution. |
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296 | // the white beam distribution will need to be flagged some other way |
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297 | // |
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298 | Print "??? Slit data is being averaged as pinhole - reset the AVERAGE parameters in the protocol ???" |
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299 | |
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300 | lambdaWidth = 0 |
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301 | endif |
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302 | |
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303 | |
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304 | ///////////////////////////// |
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305 | ///////////////////////////// |
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306 | // do the calculation |
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307 | S1 *= 0.5*0.1 //convert to radius and [cm] |
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308 | S2 *= 0.5*0.1 |
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309 | |
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310 | L1 *= 100.0 // [cm] |
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311 | L1 -= apOff //correct the distance |
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312 | |
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313 | L2 *= 100.0 |
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314 | L2 += apOff |
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315 | del_r *= 0.1 //width of annulus, convert mm to [cm] |
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316 | |
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317 | BS *= 0.5*0.1 //nominal BS diameter passed in, convert to radius and [cm] |
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318 | |
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319 | // TODO -- this empirical correction is for the geometry of the SANS beamstop location and the |
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320 | // Ordela detector construction. For now on VSANS, don't correct for the projection. |
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321 | // // 21 MAR 07 SRK - use the projected BS diameter, based on a point sample aperture |
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322 | // Variable LB |
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323 | // LB = 20.1 + 1.61*BS //distance in cm from beamstop to anode plane (empirical) |
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324 | // BS = bs + bs*lb/(l2-lb) //adjusted diameter of shadow from parallax |
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325 | |
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326 | //Start resolution calculation |
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327 | a2 = S1*L2/L1 + S2*(L1+L2)/L1 |
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328 | // q_small = 2.0*Pi*(BS-a2)*(1.0-lambdaWidth)/(lambda*L2) |
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329 | lp = 1.0/( 1.0/L1 + 1.0/L2) |
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330 | |
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331 | v_lambda = lambdaWidth^2/6.0 |
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332 | |
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333 | // if(usingLenses==1) //SRK 2007 |
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334 | if(usingLenses != 0) //SRK 2008 allows for the possibility of different numbers of lenses in header |
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335 | v_b = 0.25*(S1*L2/L1)^2 +0.25*(2/3)*(lambdaWidth/lambda)^2*(S2*L2/lp)^2 //correction to 2nd term |
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336 | else |
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337 | v_b = 0.25*(S1*L2/L1)^2 +0.25*(S2*L2/lp)^2 //original form |
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338 | endif |
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339 | |
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340 | v_d = (DDet/2.3548)^2 + del_r^2/12.0 //the 2.3548 is a conversion from FWHM->Gauss, see http://mathworld.wolfram.com/GaussianFunction.html |
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341 | vz = vz_1 / lambda |
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342 | yg = 0.5*g*L2*(L1+L2)/vz^2 |
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343 | v_g = 2.0*(2.0*yg^2*v_lambda) //factor of 2 correction, B. Hammouda, 2007 |
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344 | |
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345 | r0 = L2*tan(2.0*asin(lambda*inQ/(4.0*Pi) )) |
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346 | delta = 0.5*(BS - r0)^2/v_d |
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347 | |
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348 | if (r0 < BS) |
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349 | inc_gamma=exp(gammln(1.5))*(1-gammp(1.5,delta)) |
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350 | else |
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351 | inc_gamma=exp(gammln(1.5))*(1+gammp(1.5,delta)) |
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352 | endif |
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353 | |
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354 | fSubS = 0.5*(1.0+erf( (r0-BS)/sqrt(2.0*v_d) ) ) |
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355 | if (fSubS <= 0.0) |
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356 | fSubS = 1.e-10 |
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357 | endif |
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358 | fr = 1.0 + sqrt(v_d)*exp(-1.0*delta) /(r0*fSubS*sqrt(2.0*Pi)) |
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359 | fv = inc_gamma/(fSubS*sqrt(Pi)) - r0^2*(fr-1.0)^2/v_d |
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360 | |
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361 | rmd = fr*r0 |
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362 | v_r1 = v_b + fv*v_d +v_g |
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363 | |
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364 | rm = rmd + 0.5*v_r1/rmd |
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365 | v_r = v_r1 - 0.5*(v_r1/rmd)^2 |
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366 | if (v_r < 0.0) |
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367 | v_r = 0.0 |
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368 | endif |
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369 | QBar = (4.0*Pi/lambda)*sin(0.5*atan(rm/L2)) |
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370 | SigmaQ = QBar*sqrt(v_r/rmd^2 +v_lambda) |
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371 | |
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372 | |
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373 | // more readable method for calculating the variance in Q |
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374 | // EXCEPT - this is calculated for Qo, NOT qBar |
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375 | // (otherwise, they are nearly equivalent, except for close to the beam stop) |
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376 | // Variable kap,a_val,a_val_l2,m_h |
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377 | // g = 981.0 //gravity acceleration [cm/s^2] |
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378 | // m_h = 252.8 // m/h [=] s/cm^2 |
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379 | // |
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380 | // kap = 2*pi/lambda |
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381 | // a_val = L2*(L1+L2)*g/2*(m_h)^2 |
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382 | // a_val_L2 = a_val/L2*1e-16 //convert 1/cm^2 to 1/A^2 |
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383 | // |
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384 | // sigmaQ = 0 |
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385 | // sigmaQ = 3*(S1/L1)^2 |
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386 | // |
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387 | // if(usingLenses != 0) |
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388 | // sigmaQ += 2*(S2/lp)^2*(lambdaWidth)^2 //2nd term w/ lenses |
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389 | // else |
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390 | // sigmaQ += 2*(S2/lp)^2 //2nd term w/ no lenses |
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391 | // endif |
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392 | // |
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393 | // sigmaQ += (del_r/L2)^2 |
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394 | // sigmaQ += 2*(r0/L2)^2*(lambdaWidth)^2 |
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395 | // sigmaQ += 4*(a_val_l2)^2*lambda^4*(lambdaWidth)^2 |
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396 | // |
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397 | // sigmaQ *= kap^2/12 |
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398 | // sigmaQ = sqrt(sigmaQ) |
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399 | |
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400 | |
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401 | Return (0) |
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402 | End |
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403 | |
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404 | |
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405 | // |
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406 | //********************** |
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407 | // 2D resolution function calculation - ***NOT*** in terms of X and Y |
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408 | // but written in terms of Parallel and perpendicular to the Q vector at each point |
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409 | // |
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410 | // -- it is more naturally written this way since the 2D function is an ellipse with its major |
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411 | // axis pointing in the direction of Q_parallel. Hence there is no way to properly define the |
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412 | // elliptical gaussian in terms of sigmaX and sigmaY |
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413 | // |
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414 | // For a full description of the gravity effect on the resolution, see: |
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415 | // |
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416 | // "The effect of gravity on the resolution of small-angle neutron diffraction peaks" |
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417 | // D.F.R Mildner, J.G. Barker & S.R. Kline J. Appl. Cryst. (2011). 44, 1127-1129. |
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418 | // [ doi:10.1107/S0021889811033322 ] |
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419 | // |
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420 | // 2/17/12 SRK |
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421 | // NOTE: the first 2/3 of this code is the 1D code, copied here just to have the beam stop |
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422 | // calculation here, if I decide to implement it. The real calculation is all at the |
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423 | // bottom and is quite compact |
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424 | // |
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425 | // |
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426 | // |
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427 | // |
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428 | // - 21 MAR 07 uses projected BS diameter on the detector |
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429 | // - APR 07 still need to add resolution with lenses. currently there is no flag in the |
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430 | // raw data header to indicate the presence of lenses. |
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431 | // |
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432 | // - Aug 07 - added input to switch calculation based on lenses (==1 if in) |
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433 | // |
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434 | // passed values are read from RealsRead |
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435 | // except DDet and apOff, which are set from globals before passing |
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436 | // |
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437 | // phi is the azimuthal angle, CCW from +x axis |
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438 | // r_dist is the real-space distance from ctr of detector to QxQy pixel location |
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439 | // |
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440 | // MAR 2011 - removed the del_r terms, they don't apply since no binning is done to the 2D data |
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441 | // |
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442 | Function V_get2DResolution(inQ,phi,r_dist,folderStr,type,collimationStr,SigmaQX,SigmaQY,fSubS) |
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443 | Variable inQ,phi,r_dist |
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444 | String folderStr,type,collimationStr |
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445 | Variable &SigmaQX,&SigmaQY,&fSubS //these are the output quantities at the input Q value |
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446 | // Variable SigmaQX,SigmaQY,fSubS //these are the output quantities at the input Q value |
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447 | |
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448 | |
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449 | Variable lambda, lambdaWidth, DDet, apOff, S1, S2, L1, L2, BS, del_r,usingLenses |
---|
450 | |
---|
451 | // phi = FindPhi( pixSize*((p+1)-xctr) , pixSize*((q+1)-yctr)+(2)*yg_d) //(dx,dy+yg_d) |
---|
452 | // r_dist = sqrt( (pixSize*((p+1)-xctr))^2 + (pixSize*((q+1)-yctr)+(2)*yg_d)^2 ) //radial distance from ctr to pt |
---|
453 | |
---|
454 | ///////// get all of the values from the header |
---|
455 | // TODO: check the units of all of the inputs |
---|
456 | // lambda = wavelength [A] |
---|
457 | lambda = V_getWavelength(folderStr) |
---|
458 | |
---|
459 | // lambdaWidth = [dimensionless] |
---|
460 | lambdaWidth = V_getWavelength_spread(folderStr) |
---|
461 | |
---|
462 | // DDet = detector pixel resolution [cm] **assumes square pixel |
---|
463 | // V_getDet_pixel_fwhm_x(folderStr,detStr) |
---|
464 | // V_getDet_pixel_fwhm_y(folderStr,detStr) |
---|
465 | // DDet = 0.8 // TODO -- this is hard-wired |
---|
466 | |
---|
467 | if(strlen(type) == 1) |
---|
468 | // it's "B" |
---|
469 | DDet = V_getDet_pixel_fwhm_x(folderStr,type) // value is already in cm |
---|
470 | else |
---|
471 | DDet = V_getDet_pixel_fwhm_x(folderStr,type[0,1]) // value is already in cm |
---|
472 | endif |
---|
473 | |
---|
474 | // apOff = sample aperture to sample distance [cm] |
---|
475 | apOff = 10 // TODO -- this is hard-wired |
---|
476 | |
---|
477 | |
---|
478 | // S1 = source aperture diameter [mm] |
---|
479 | // may be either circle or rectangle |
---|
480 | String s1_shape="",bs_shape="" |
---|
481 | Variable width,height,equiv_S1,equiv_bs |
---|
482 | |
---|
483 | s1_shape = V_getSourceAp_shape(folderStr) |
---|
484 | if(cmpstr(s1_shape,"CIRCLE") == 0) |
---|
485 | S1 = str2num(V_getSourceAp_size(folderStr)) |
---|
486 | else |
---|
487 | S1 = V_getSourceAp_height(folderStr) // TODO: need the width or at least an equivalent diameter |
---|
488 | endif |
---|
489 | |
---|
490 | |
---|
491 | // S2 = sample aperture diameter [cm] |
---|
492 | // as of 3/2018, the "internal" sample aperture is not in use, only the external |
---|
493 | // TODO : verify the units on the Ap2 (external) |
---|
494 | // sample aperture 1(internal) is set to report "12.7 mm" as a STRING |
---|
495 | // sample aperture 2(external) reports the number typed in... |
---|
496 | // |
---|
497 | // so I'm trusting [cm] is in the file |
---|
498 | S2 = V_getSampleAp2_size(folderStr)*10 // sample ap 1 or 2? 2 = the "external", convert to [mm] |
---|
499 | |
---|
500 | // L1 = source to sample distance [m] |
---|
501 | L1 = V_getSourceAp_distance(folderStr)/100 |
---|
502 | |
---|
503 | // L2 = sample to detector distance [m] |
---|
504 | // take the first two characters of the "type" to get the correct distance. |
---|
505 | // if the type is say, MLRTB, then the implicit assumption in combining all four panels is that the resolution |
---|
506 | // is not an issue for the slightly different distances. |
---|
507 | if(strlen(type) == 1) |
---|
508 | // it's "B" |
---|
509 | L2 = V_getDet_ActualDistance(folderStr,type)/100 //convert cm to m |
---|
510 | else |
---|
511 | L2 = V_getDet_ActualDistance(folderStr,type[0,1])/100 //convert cm to m |
---|
512 | endif |
---|
513 | |
---|
514 | // BS = beam stop diameter [mm] |
---|
515 | //TODO:? which BS is in? carr2, carr3, none? |
---|
516 | // -- need to check the detector, num_beamstops field, then description, then shape/size or shape/height and shape/width |
---|
517 | // |
---|
518 | // TODO: the values in the file are incorrect!!! BS = 1000 mm diameter!!! |
---|
519 | BS = V_IdentifyBeamstopDiameter(folderStr,type) //returns diameter in [mm] |
---|
520 | // BS = V_getBeamStopC2_size(folderStr) // Units are [mm] |
---|
521 | // BS = 25.4 //TODO hard-wired value |
---|
522 | |
---|
523 | // bs_shape = V_getBeamStopC2_shape(folderStr) |
---|
524 | // if(cmpstr(s1_shape,"CIRCLE") == 0) |
---|
525 | // bs = V_getBeamStopC2_size(folderStr) |
---|
526 | // else |
---|
527 | // bs = V_getBeamStopC2_height(folderStr) |
---|
528 | // endif |
---|
529 | |
---|
530 | |
---|
531 | |
---|
532 | // del_r = step size [mm] = binWidth*(mm/pixel) |
---|
533 | del_r = 1*DDet*10 // TODO: this is probably not the correct value |
---|
534 | |
---|
535 | // usingLenses = flag for lenses = 0 if no lenses, non-zero if lenses are in-beam |
---|
536 | usingLenses = 0 |
---|
537 | |
---|
538 | //if(cmpstr(type[0,1],"FL")==0) |
---|
539 | // Print "(FL) Resolution lambda,lambdaWidth,DDet,apOff,S1,S2,L1,L2,BS,del_r,usingLenses" |
---|
540 | // Print lambda,lambdaWidth,DDet,apOff,S1,S2,L1,L2,BS,del_r,usingLenses |
---|
541 | //endif |
---|
542 | |
---|
543 | |
---|
544 | |
---|
545 | // TODO: |
---|
546 | // this is the point where I need to switch on the different collimation types (white beam, slit, Xtal, etc) |
---|
547 | // to calculate the correct resolution, or fill the waves with the correct "flags" |
---|
548 | // |
---|
549 | |
---|
550 | // For white beam data, the wavelength distribution can't be represented as a gaussian, but all of the other |
---|
551 | // geometric corrections still apply. Passing zero for the lambdaWidth will return the geometry contribution, |
---|
552 | // as long as the wavelength can be handled separately. It appears to be correct to do as a double integral, |
---|
553 | // with the inner(lambda) calculated first, then the outer(geometry). |
---|
554 | // |
---|
555 | |
---|
556 | // possible values are: |
---|
557 | // |
---|
558 | // pinhole |
---|
559 | // pinhole_whiteBeam |
---|
560 | // convergingPinholes |
---|
561 | // |
---|
562 | // *slit data should be reduced using the slit routine, not here, proceed but warn |
---|
563 | // narrowSlit |
---|
564 | // narrowSlit_whiteBeam |
---|
565 | |
---|
566 | |
---|
567 | if(cmpstr(collimationStr,"pinhole") == 0) |
---|
568 | //nothing to change |
---|
569 | endif |
---|
570 | |
---|
571 | if(cmpstr(collimationStr,"pinhole_whiteBeam") == 0) |
---|
572 | // set lambdaWidth == 0 so that the gaussian resolution calculates only the geometry contribution. |
---|
573 | // the white beam distribution will need to be flagged some other way |
---|
574 | // |
---|
575 | lambdaWidth = 0 |
---|
576 | endif |
---|
577 | |
---|
578 | if(cmpstr(collimationStr,"convergingPinholes") == 0) |
---|
579 | |
---|
580 | // set usingLenses == 1 so that the Gaussian resolution calculation will be for a focus condition |
---|
581 | usingLenses = 1 |
---|
582 | endif |
---|
583 | |
---|
584 | |
---|
585 | // should not end up here, except for odd testing cases |
---|
586 | if(cmpstr(collimationStr,"narrowSlit") == 0) |
---|
587 | |
---|
588 | Print "??? Slit data is being averaged as pinhole - reset the AVERAGE parameters in the protocol ???" |
---|
589 | endif |
---|
590 | |
---|
591 | // should not end up here, except for odd testing cases |
---|
592 | if(cmpstr(collimationStr,"narrowSlit_whiteBeam") == 0) |
---|
593 | |
---|
594 | // set lambdaWidth == 0 so that the gaussian resolution calculates only the geometry contribution. |
---|
595 | // the white beam distribution will need to be flagged some other way |
---|
596 | // |
---|
597 | Print "??? Slit data is being averaged as pinhole - reset the AVERAGE parameters in the protocol ???" |
---|
598 | |
---|
599 | lambdaWidth = 0 |
---|
600 | endif |
---|
601 | |
---|
602 | |
---|
603 | |
---|
604 | //lots of calculation variables |
---|
605 | Variable a2, lp, v_lambda, v_b, v_d, vz, yg, v_g |
---|
606 | Variable r0, delta, inc_gamma, fr, fv, rmd, v_r1, rm, v_r |
---|
607 | |
---|
608 | //Constants |
---|
609 | Variable vz_1 = 3.956e5 //velocity [cm/s] of 1 A neutron |
---|
610 | Variable g = 981.0 //gravity acceleration [cm/s^2] |
---|
611 | Variable m_h = 252.8 // m/h [=] s/cm^2 |
---|
612 | |
---|
613 | |
---|
614 | S1 *= 0.5*0.1 //convert to radius and [cm] |
---|
615 | S2 *= 0.5*0.1 |
---|
616 | |
---|
617 | L1 *= 100.0 // [cm] |
---|
618 | L1 -= apOff //correct the distance |
---|
619 | |
---|
620 | L2 *= 100.0 |
---|
621 | L2 += apOff |
---|
622 | del_r *= 0.1 //width of annulus, convert mm to [cm] |
---|
623 | |
---|
624 | BS *= 0.5*0.1 //nominal BS diameter passed in, convert to radius and [cm] |
---|
625 | // 21 MAR 07 SRK - use the projected BS diameter, based on a point sample aperture |
---|
626 | Variable LB |
---|
627 | LB = 20.1 + 1.61*BS //distance in cm from beamstop to anode plane (empirical) |
---|
628 | BS = bs + bs*lb/(l2-lb) //adjusted diameter of shadow from parallax |
---|
629 | |
---|
630 | //Start resolution calculation |
---|
631 | a2 = S1*L2/L1 + S2*(L1+L2)/L1 |
---|
632 | lp = 1.0/( 1.0/L1 + 1.0/L2) |
---|
633 | |
---|
634 | v_lambda = lambdaWidth^2/6.0 |
---|
635 | |
---|
636 | // if(usingLenses==1) //SRK 2007 |
---|
637 | if(usingLenses != 0) //SRK 2008 allows for the possibility of different numbers of lenses in header |
---|
638 | v_b = 0.25*(S1*L2/L1)^2 +0.25*(2/3)*(lambdaWidth/lambda)^2*(S2*L2/lp)^2 //correction to 2nd term |
---|
639 | else |
---|
640 | v_b = 0.25*(S1*L2/L1)^2 +0.25*(S2*L2/lp)^2 //original form |
---|
641 | endif |
---|
642 | |
---|
643 | v_d = (DDet/2.3548)^2 + del_r^2/12.0 |
---|
644 | vz = vz_1 / lambda |
---|
645 | yg = 0.5*g*L2*(L1+L2)/vz^2 |
---|
646 | v_g = 2.0*(2.0*yg^2*v_lambda) //factor of 2 correction, B. Hammouda, 2007 |
---|
647 | |
---|
648 | r0 = L2*tan(2.0*asin(lambda*inQ/(4.0*Pi) )) |
---|
649 | delta = 0.5*(BS - r0)^2/v_d |
---|
650 | |
---|
651 | if (r0 < BS) |
---|
652 | inc_gamma=exp(gammln(1.5))*(1-gammp(1.5,delta)) |
---|
653 | else |
---|
654 | inc_gamma=exp(gammln(1.5))*(1+gammp(1.5,delta)) |
---|
655 | endif |
---|
656 | |
---|
657 | fSubS = 0.5*(1.0+erf( (r0-BS)/sqrt(2.0*v_d) ) ) |
---|
658 | if (fSubS <= 0.0) |
---|
659 | fSubS = 1.e-10 |
---|
660 | endif |
---|
661 | // fr = 1.0 + sqrt(v_d)*exp(-1.0*delta) /(r0*fSubS*sqrt(2.0*Pi)) |
---|
662 | // fv = inc_gamma/(fSubS*sqrt(Pi)) - r0^2*(fr-1.0)^2/v_d |
---|
663 | // |
---|
664 | // rmd = fr*r0 |
---|
665 | // v_r1 = v_b + fv*v_d +v_g |
---|
666 | // |
---|
667 | // rm = rmd + 0.5*v_r1/rmd |
---|
668 | // v_r = v_r1 - 0.5*(v_r1/rmd)^2 |
---|
669 | // if (v_r < 0.0) |
---|
670 | // v_r = 0.0 |
---|
671 | // endif |
---|
672 | |
---|
673 | Variable kap,a_val,a_val_L2,proj_DDet |
---|
674 | |
---|
675 | kap = 2*pi/lambda |
---|
676 | a_val = L2*(L1+L2)*g/2*(m_h)^2 |
---|
677 | a_val_L2 = a_val/L2*1e-16 //convert 1/cm^2 to 1/A^2 |
---|
678 | |
---|
679 | |
---|
680 | // the detector pixel is square, so correct for phi |
---|
681 | proj_DDet = DDet*cos(phi) + DDet*sin(phi) |
---|
682 | |
---|
683 | |
---|
684 | ///////// OLD - don't use --- |
---|
685 | //in terms of Q_parallel ("x") and Q_perp ("y") - this works, since parallel is in the direction of Q and I |
---|
686 | // can calculate that from the QxQy (I just need the projection) |
---|
687 | //// for test case with no gravity, set a_val = 0 |
---|
688 | //// note that gravity has no wavelength dependence. the lambda^4 cancels out. |
---|
689 | //// |
---|
690 | //// a_val = 0 |
---|
691 | //// a_val_l2 = 0 |
---|
692 | // |
---|
693 | // |
---|
694 | // // this is really sigma_Q_parallel |
---|
695 | // SigmaQX = kap*kap/12 * (3*(S1/L1)^2 + 3*(S2/LP)^2 + (proj_DDet/L2)^2 + (sin(phi))^2*8*(a_val_L2)^2*lambda^4*lambdaWidth^2) |
---|
696 | // SigmaQX += inQ*inQ*v_lambda |
---|
697 | // |
---|
698 | // //this is really sigma_Q_perpendicular |
---|
699 | // proj_DDet = DDet*sin(phi) + DDet*cos(phi) //not necessary, since DDet is the same in both X and Y directions |
---|
700 | // |
---|
701 | // SigmaQY = kap*kap/12 * (3*(S1/L1)^2 + 3*(S2/LP)^2 + (proj_DDet/L2)^2 + (cos(phi))^2*8*(a_val_L2)^2*lambda^4*lambdaWidth^2) |
---|
702 | // |
---|
703 | // SigmaQX = sqrt(SigmaQX) |
---|
704 | // SigmaQy = sqrt(SigmaQY) |
---|
705 | // |
---|
706 | |
---|
707 | ///////////////////////////////////////////////// |
---|
708 | ///// |
---|
709 | // ////// this is all new, inclusion of gravity effect into the parallel component |
---|
710 | // perpendicular component is purely geometric, no gravity component |
---|
711 | // |
---|
712 | // the shadow factor is calculated as above -so keep the above calculations, even though |
---|
713 | // most of them are redundant. |
---|
714 | // |
---|
715 | |
---|
716 | //// // |
---|
717 | Variable yg_d,acc,sdd,ssd,lambda0,DL_L,sig_l |
---|
718 | Variable var_qlx,var_qly,var_ql,qx,qy,sig_perp,sig_para, sig_para_new |
---|
719 | |
---|
720 | G = 981. //! ACCELERATION OF GRAVITY, CM/SEC^2 |
---|
721 | acc = vz_1 // 3.956E5 //! CONVERT WAVELENGTH TO VELOCITY CM/SEC |
---|
722 | SDD = L2 //1317 |
---|
723 | SSD = L1 //1627 //cm |
---|
724 | lambda0 = lambda // 15 |
---|
725 | DL_L = lambdaWidth //0.236 |
---|
726 | SIG_L = DL_L/sqrt(6) |
---|
727 | YG_d = -0.5*G*SDD*(SSD+SDD)*(LAMBDA0/acc)^2 |
---|
728 | ///// Print "DISTANCE BEAM FALLS DUE TO GRAVITY (CM) = ",YG |
---|
729 | // Print "Gravity q* = ",-2*pi/lambda0*2*yg_d/sdd |
---|
730 | |
---|
731 | sig_perp = kap*kap/12 * (3*(S1/L1)^2 + 3*(S2/LP)^2 + (proj_DDet/L2)^2) |
---|
732 | sig_perp = sqrt(sig_perp) |
---|
733 | |
---|
734 | // TODO -- not needed??? |
---|
735 | // FindQxQy(inQ,phi,qx,qy) |
---|
736 | |
---|
737 | |
---|
738 | // missing a factor of 2 here, and the form is different than the paper, so re-write |
---|
739 | // VAR_QLY = SIG_L^2 * (QY+4*PI*YG_d/(2*SDD*LAMBDA0))^2 |
---|
740 | // VAR_QLX = (SIG_L*QX)^2 |
---|
741 | // VAR_QL = VAR_QLY + VAR_QLX //! WAVELENGTH CONTRIBUTION TO VARIANCE |
---|
742 | // sig_para = (sig_perp^2 + VAR_QL)^0.5 |
---|
743 | |
---|
744 | // r_dist is passed in, [=]cm |
---|
745 | // from the paper |
---|
746 | a_val = 0.5*G*SDD*(SSD+SDD)*m_h^2 * 1e-16 //units now are cm /(A^2) |
---|
747 | |
---|
748 | var_QL = 1/6*(kap/SDD)^2*(DL_L)^2*(r_dist^2 - 4*r_dist*a_val*lambda0^2*sin(phi) + 4*a_val^2*lambda0^4) |
---|
749 | sig_para_new = (sig_perp^2 + VAR_QL)^0.5 |
---|
750 | |
---|
751 | |
---|
752 | ///// return values PBR |
---|
753 | SigmaQX = sig_para_new |
---|
754 | SigmaQy = sig_perp |
---|
755 | |
---|
756 | //// |
---|
757 | |
---|
758 | Return (0) |
---|
759 | End |
---|
760 | |
---|
761 | |
---|
762 | |
---|
763 | |
---|
764 | |
---|