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
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  • sans/Dev/trunk/NCNR_User_Procedures/Reduction/SANS/HFIR_Utils.ipf

    r750 r795  
    164164// detStr is passed as TextRead[9] and is an identifier for the detector 
    165165// 
    166 Function DetectorDeadtime(fileStr,detStr) 
    167         String fileStr,detStr 
     166// [dateAndTimeStr] is optional, and could be used as a switch for  
     167// different historical detector configurations 
     168Function DetectorDeadtime(fileStr,detStr,[dateAndTimeStr]) 
     169        String fileStr,detStr,dateAndTimeStr 
    168170         
    169171        Variable deadtime 
     
    977979// called by Correct.ipf, ProtocolAsPanel.ipf, Transmission.ipf 
    978980// 
    979 Function AttenuationFactor(fileStr,lam,attenuation) 
     981// atten_err is one std. deviation, passed back by reference 
     982Function AttenuationFactor(fileStr,lam,attenuation, atten_err) 
    980983        String fileStr 
    981         Variable lam,attenuation  //    0 =< attenuation <= 100 (%) : where no attenuator stands for 0. 
     984        Variable lam,attenuation, &atten_err  //    0 =< attenuation <= 100 (%) : where no attenuator stands for 0. 
    982985         
    983986        Variable attenFactor=1 
     
    986989        attenFactor = 1- attenuation*0.01  //???Attenuate transmission 
    987990 
     991        // Change April 2011 - now returns error in atten trans 
     992        atten_err = 0 
     993         
    988994        return(attenFactor) 
    989995End 
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