Ignore:
Timestamp:
Feb 28, 2012 4:51:26 PM (10 years ago)
Author:
srkline
Message:

adding two new help files for real space modeling and description of the 2D resolution function

cleaning up the FFT routines for addition as a beta operation

File:
1 edited

Legend:

Unmodified
Added
Removed
  • sans/Dev/trunk/NCNR_User_Procedures/Reduction/SANS/NCNR_Utils.ipf

    r827 r838  
    190190// but written in terms of Parallel and perpendicular to the Q vector at each point 
    191191// 
    192 // -- it must be written this way since the 2D function is an ellipse with its major 
     192// -- it is more naturally written this way since the 2D function is an ellipse with its major 
    193193// axis pointing in the direction of Q_parallel. Hence there is no way to properly define the  
    194194// elliptical gaussian in terms of sigmaX and sigmaY 
    195195// 
    196 // based on notes from David Mildner, 2008 
     196// For a full description of the gravity effect on the resolution, see: 
     197// 
     198//      "The effect of gravity on the resolution of small-angle neutron diffraction peaks" 
     199//      D.F.R Mildner, J.G. Barker & S.R. Kline J. Appl. Cryst. (2011). 44, 1127-1129. 
     200//      [ doi:10.1107/S0021889811033322 ] 
     201// 
     202//              2/17/12 SRK 
     203//              NOTE: the first 2/3 of this code is the 1D code, copied here just to have the beam stop 
     204//                              calculation here, if I decide to implement it. The real calculation is all at the  
     205//                              bottom and is quite compact 
     206// 
     207// 
    197208// 
    198209// 
     
    324335//      ////// this is all new, inclusion of gravity effect into the parallel component 
    325336//       perpendicular component is purely geometric, no gravity component 
     337// 
     338// the shadow factor is calculated as above -so keep the above calculations, even though 
     339// most of them are redundant. 
     340// 
     341         
    326342////    // 
    327343        Variable yg_d,acc,sdd,ssd,lambda0,DL_L,sig_l 
    328344        Variable var_qlx,var_qly,var_ql,qx,qy,sig_perp,sig_para, sig_para_new 
     345         
    329346        G = 981.  //!   ACCELERATION OF GRAVITY, CM/SEC^2 
    330347        acc = vz_1              //      3.956E5 //!     CONVERT WAVELENGTH TO VELOCITY CM/SEC 
     
    336353        YG_d = -0.5*G*SDD*(SSD+SDD)*(LAMBDA0/acc)^2 
    337354/////   Print "DISTANCE BEAM FALLS DUE TO GRAVITY (CM) = ",YG 
     355//              Print "Gravity q* = ",-2*pi/lambda0*2*yg_d/sdd 
    338356         
    339357        sig_perp = kap*kap/12 * (3*(S1/L1)^2 + 3*(S2/LP)^2 + (proj_DDet/L2)^2) 
Note: See TracChangeset for help on using the changeset viewer.