Ignore:
Timestamp:
Apr 4, 2011 12:18:33 PM (11 years ago)
Author:
srkline
Message:

Changes to SANS reduction that apply to other Facilities:

These changes are related to the propagation of errors in 2D, on a
per-pixel basis. These changes only affect the errors that are reported in
the QxQy? ASCII file output. The 1D code is unaffected.

If these changes are not implemented, then errors of zero will be substitued as defaults
for these experimental errors.

Upon data loading, an error matrix, linear_data_error is generated and filled with
error values appropriate for Poisson statistics (not simply sqrt(n)).

4 functions in FACILITY_DataReadWrite.ipf have been added, and they are rather
self-explanatory:

In FACILITY_Utils.ipf, the AttenuatorTransmission?() function now returns
an additional parameter, atten_err, which is one standard deviation of the
attenuator transmission value. It returns a default error=0 (which is
correct if no attenuation is used). Facilities can fill this function in
with their own estimates for the uncertainty in the attenutator transmission.

File:
1 edited

Legend:

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

    r764 r795  
    175175// detStr is passed as TextRead[9] and is an identifier for the detector 
    176176// 
    177 Function DetectorDeadtime(fileStr,detStr) 
    178         String fileStr,detStr 
     177// [dateAndTimeStr] is optional, and could be used as a switch for  
     178// different historical detector configurations 
     179Function DetectorDeadtime(fileStr,detStr,[dateAndTimeStr]) 
     180        String fileStr,detStr,dateAndTimeStr 
    179181         
    180182        Variable deadtime 
    181183         
    182 // your code here 
    183 deadtime = (2e-6) 
     184        // your code here 
     185        deadtime = (2e-6) 
    184186 
    185187        return(deadtime) 
     
    922924// called by Correct.ipf, ProtocolAsPanel.ipf, Transmission.ipf 
    923925// 
    924 Function AttenuationFactor(fileStr,lam,attenNo) 
     926// atten_err is one std. deviation, passed back by reference 
     927Function AttenuationFactor(fileStr,lam,attenNo,atten_err) 
    925928        String fileStr 
    926         Variable lam,attenNo 
     929        Variable lam,attenNo,&atten_err 
    927930         
    928931        Variable attenFactor 
     
    930933         
    931934        attenFactor = Attenuators_ILL[attenNo] 
    932          
     935 
     936        // Change April 2011 - now returns error in atten trans 
     937        atten_err = 0 
     938                 
    933939//      print attenfactor 
    934940         
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