Changeset 597 for sans/Dev

Timestamp:

Nov 5, 2009 2:11:20 PM (13 years ago)

Author:

srkline

Message:

Updated SASCALC with newly measured flux data for both NG3 and NG7.

-At 6A on NG7, now SASCALC is within +/- 5% of the measured value.
-At 6A on NG3, now SASCALC is +15% compared to the measured value.

The average detector efficiency is now included in the simulation (e=0.75) since the cts/s from SASCALC is flux on sample, not as would be measured at the detector.

Location:

sans/Dev/trunk/NCNR_User_Procedures/Reduction/SANS

Files:

• MultScatter_MonteCarlo_2D.ipf (modified) (3 diffs)
• SASCALC.ipf (modified) (8 diffs)

sans/Dev/trunk/NCNR_User_Procedures/Reduction/SANS/MultScatter_MonteCarlo_2D.ipf

@@ -1238 +1238 @@
         t0 = (stopMSTimer(-2) - t0)*1e-6
         t0 *= imon/1000/ThreadProcessorCount                    //projected time, in seconds (using threads for the calculation)
-        inputWave[0] = imon             //reset
+
+// to correct for detector efficiency, send only the fraction of neutrons that are actually counted     
+        NVAR detectorEff = root:Packages:NIST:SAS:g_detectorEff
+
+        inputWave[0] = imon     * detectorEff                   //reset number of input neutrons before full simulation
         
         if(t0>10)
@@ -1687 +1691 @@
         NVAR estTrans = root:Packages:NIST:SAS:g_1DEstTrans             // estimated transmission of sample
         NVAR mScat = root:Packages:NIST:SAS:g_MultScattFraction
+        NVAR detectorEff = root:Packages:NIST:SAS:g_detectorEff
         
         WAVE rw=root:Packages:NIST:SAS:realsRead
@@ -1749 +1754 @@
         
 //                              aveint = (Imon)*prob_i / circle_fraction / nCells_expected
-        aveint = (Imon)*prob_i
+// added correction for detector efficiency, since SASCALC is flux on sample
+        aveint = (Imon)*prob_i*detectorEff
 
         countsInAnnulus = aveint*nCells

sans/Dev/trunk/NCNR_User_Procedures/Reduction/SANS/SASCALC.ipf

@@ -136 +136 @@
         Variable/G root:Packages:NIST:SAS:g_1D_AddNoise = 1
         Variable/G root:Packages:NIST:SAS:g_MultScattFraction=0
+        Variable/G root:Packages:NIST:SAS:g_detectorEff=0.75                    //averag value for most wavelengths
         
         //tick labels for SDD slider
@@ -165 +166 @@
         Variable/G del_r = 0.5
         Variable/G det_width = 64.0
-        Variable/G phi_0 = 2.95e13
         Variable/G lambda_t = 5.50
         Variable/G l2r_lower = 132.3
@@ -179 +179 @@
         Variable/G guide_width = 6.0
         Variable/G idmax = 100.0
-        Variable/G b = 0.023
-        Variable/G c = 0.023
+//      //old values, from 3/2002
+//      Variable/G phi_0 = 2.95e13
+//      Variable/G b = 0.023
+//      Variable/G c = 0.023
+
+        //new values, from 2/2009
+        Variable/G phi_0 = 3.4e13
+        Variable/G b = 0.0185
+        Variable/G c = 0.0135
         
         //fwhm values (new variables) (+3, 0, -3, calibrated 2009)
@@ -219 +226 @@
         Variable/G del_r = 0.5
         Variable/G det_width = 64.0
-        Variable/G phi_0 = 2.3e13
         Variable/G lambda_t = 5.50
         Variable/G l2r_lower = 100
@@ -233 +239 @@
         Variable/G guide_width = 5.0
         Variable/G idmax = 100.0
-        Variable/G b = 0.028
-        Variable/G c = 0.028
+        
+//      //old values, from 3/2002
+//      Variable/G phi_0 = 2.3e13
+//      Variable/G b = 0.028
+//      Variable/G c = 0.028
+
+        //new values, from 6/2009       
+        Variable/G phi_0 = 3.2e13
+        Variable/G b = 0.0448
+        Variable/G c = 0.0463
         
         //fwhm values (new variables)
         Variable/G fwhm_narrow = 0.09
-        Variable/G fwhm_mid = 0.11
+        Variable/G fwhm_mid = 0.115             //2009
         Variable/G fwhm_wide = 0.22
         
@@ -484 +498 @@
                 endswitch
                 
-                dlStr = "0.09;0.11;0.22;"
+                dlStr = "0.09;0.115;0.22;"
                 Slider SC_Slider_1,limits={100,1531,1},userTicks={root:Packages:NIST:SAS:tickSDDNG7,root:Packages:NIST:SAS:lblSDDNG7 }
                 SetVariable setvar0,limits={100,1531,1}
@@ -1982 +1996 @@
 End
 
-
+// updated with new flux numbers from John Barker
+// NG3 - Feb 2009
+// NG7 - July 2009
+//
+// guide loss has been changed to 0.95 rather than the old value of 0.95
+//
+// other values are changed in the initialization routines
+//
 Function beamIntensity()
 
     Variable alpha,f,t,t4,t5,t6,as,solid_angle,l1,d2_phi
-    Variable a1,a2,retVal
+    Variable a1,a2,retVal,guide_loss=0.95
     SetDataFolder root:Packages:NIST:SAS
     NVAR l_gap=l_gap,guide_width =guide_width,ng = gNg
@@ -2001 +2022 @@
     f = l_gap*alpha/(2*guide_width)
     t4 = (1-f)*(1-f)
-    t5 = exp(ng*ln(0.96))       // trans losses of guides in pre-sample flight
+    t5 = exp(ng*ln(guide_loss)) // trans losses of guides in pre-sample flight
     t6 = 1 - lambda*(b-(ng/8)*(b-c))            //experimental correction factor
     t = t1*t2*t3*t4*t5*t6