Changeset 509 for sans/Dev/trunk/NCNR_User_Procedures/Reduction/SANS/NCNR_Utils.ipf

Timestamp:

May 18, 2009 5:15:08 PM (13 years ago)

Author:

srkline

Message:

(1) fix in ProtocolAsPanel? that correctly calculates Kappa for data taken with the Cerca detectors. In the Kappa calculation, the data is manually scaled, bypassing the normal "ADD" step where the 4x detector data is correctly renormalized. Added a flag to divide by 4 if ILL detector type found.

(2) lots of bits to try to accomodate 2D resolution smearing. Changes to the QxQy? output to have everything needed: Qz, sigX, sigY, and shadowing. So presumably, all of the information is in the reduced data, where it should be.

• added a 2D resolution calculation based on David Mildner's notes.
• added 2D quadrature calculation for smearing, and new structure definitions

---

File:

• sans/Dev/trunk/NCNR_User_Procedures/Reduction/SANS/NCNR_Utils.ipf (modified) (1 diff)

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

@@ -152 +152 @@
         Return results
 End
+
+//
+//
+//      this should end up in NCNR_Utils once it's fully functional
+//
+// lots of unnecessary junk...
+//
+//**********************
+// 2D resolution function calculation - in terms of X and Y
+//
+// based on notes from David Mildner, 2008
+//
+// - 21 MAR 07 uses projected BS diameter on the detector
+// - APR 07 still need to add resolution with lenses. currently there is no flag in the 
+//          raw data header to indicate the presence of lenses.
+//
+// - Aug 07 - added input to switch calculation based on lenses (==1 if in)
+//
+// passed values are read from RealsRead
+// except DDet and apOff, which are set from globals before passing
+//
+// phi is the azimuthal angle, CCW from +x axis
+// r_dist is the real-space distance from ctr of detector to QxQy pixel location
+//
+Function/S get2DResolution(inQ,phi,lambda,lambdaWidth,DDet,apOff,S1,S2,L1,L2,BS,del_r,usingLenses,r_dist,SigmaQX,SigmaQY,fSubS)
+        Variable inQ, phi,lambda, lambdaWidth, DDet, apOff, S1, S2, L1, L2, BS, del_r,usingLenses,r_dist
+        Variable &SigmaQX,&SigmaQY,&fSubS               //these are the output quantities at the input Q value
+        
+        //lots of calculation variables
+        Variable a2, lp, v_lambda, v_b, v_d, vz, yg, v_g
+        Variable r0, delta, inc_gamma, fr, fv, rmd, v_r1, rm, v_r
+
+        //Constants
+        Variable vz_1 = 3.956e5         //velocity [cm/s] of 1 A neutron
+        Variable g = 981.0                              //gravity acceleration [cm/s^2]
+        Variable h_m = 3995                             // h/m [=] A*m/s
+
+        String results
+        results ="Failure"
+
+        S1 *= 0.5*0.1                   //convert to radius and [cm]
+        S2 *= 0.5*0.1
+
+        L1 *= 100.0                     // [cm]
+        L1 -= apOff                             //correct the distance
+
+        L2 *= 100.0
+        L2 += apOff
+        del_r *= 0.1                            //width of annulus, convert mm to [cm]
+        
+        BS *= 0.5*0.1                   //nominal BS diameter passed in, convert to radius and [cm]
+        // 21 MAR 07 SRK - use the projected BS diameter, based on a point sample aperture
+        Variable LB
+        LB = 20.1 + 1.61*BS                     //distance in cm from beamstop to anode plane (empirical)
+        BS = bs + bs*lb/(l2-lb)         //adjusted diameter of shadow from parallax
+        
+        //Start resolution calculation
+        a2 = S1*L2/L1 + S2*(L1+L2)/L1
+        lp = 1.0/( 1.0/L1 + 1.0/L2)
+
+        v_lambda = lambdaWidth^2/6.0
+        
+//      if(usingLenses==1)                      //SRK 2007
+        if(usingLenses != 0)                    //SRK 2008 allows for the possibility of different numbers of lenses in header
+                v_b = 0.25*(S1*L2/L1)^2 +0.25*(2/3)*(lambdaWidth/lambda)^2*(S2*L2/lp)^2         //correction to 2nd term
+        else
+                v_b = 0.25*(S1*L2/L1)^2 +0.25*(S2*L2/lp)^2              //original form
+        endif
+        
+        v_d = (DDet/2.3548)^2 + del_r^2/12.0
+        vz = vz_1 / lambda
+        yg = 0.5*g*L2*(L1+L2)/vz^2
+        v_g = 2.0*(2.0*yg^2*v_lambda)                                   //factor of 2 correction, B. Hammouda, 2007
+
+        r0 = L2*tan(2.0*asin(lambda*inQ/(4.0*Pi) ))
+        delta = 0.5*(BS - r0)^2/v_d
+
+        if (r0 < BS) 
+                inc_gamma=exp(gammln(1.5))*(1-gammp(1.5,delta))
+        else
+                inc_gamma=exp(gammln(1.5))*(1+gammp(1.5,delta))
+        endif
+
+        fSubS = 0.5*(1.0+erf( (r0-BS)/sqrt(2.0*v_d) ) )
+        if (fSubS <= 0.0) 
+                fSubS = 1.e-10
+        endif
+//      fr = 1.0 + sqrt(v_d)*exp(-1.0*delta) /(r0*fSubS*sqrt(2.0*Pi))
+//      fv = inc_gamma/(fSubS*sqrt(Pi)) - r0^2*(fr-1.0)^2/v_d
+//
+//      rmd = fr*r0
+//      v_r1 = v_b + fv*v_d +v_g
+//
+//      rm = rmd + 0.5*v_r1/rmd
+//      v_r = v_r1 - 0.5*(v_r1/rmd)^2
+//      if (v_r < 0.0) 
+//              v_r = 0.0
+//      endif
+
+        Variable kap,a_val
+        
+        kap = 2*pi/lambda
+        a_val = (L1+L2)*g/2/(h_m)^2
+        
+        SigmaQX = 3*(S1/L1)^2 + 3*(S2/LP)^2 + 2*(DDet/L2)^2 + 2*(r_dist/L2)^2*(lambdaWidth)^2*(cos(phi))^2
+
+        SigmaQY = 3*(S1/L1)^2 + 3*(S2/LP)^2 + 2*(DDet/L2)^2 + 2*(r_dist/L2)^2*(lambdaWidth)^2*(sin(phi))^2 + 8*(a_val/L2)^2*lambda^4*lambdaWidth^2
+
+        SigmaQX = sqrt(kap*kap/12*SigmaQX)
+        SigmaQy = sqrt(kap*kap/12*SigmaQY)
+
+        results = "success"
+        Return results
+End
+
+