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:

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

    r715 r795  
    166166// detStr is passed as TextRead[9] and is an identifier for the detector 
    167167// 
    168 Function DetectorDeadtime(fileStr,detStr) 
    169         String fileStr,detStr 
     168// [dateAndTimeStr] is optional, and could be used as a switch for  
     169// different historical detector configurations 
     170Function DetectorDeadtime(fileStr,detStr,[dateAndTimeStr]) 
     171        String fileStr,detStr,dateAndTimeStr 
    170172         
    171173        Variable deadtime 
     
    886888// called by Correct.ipf, ProtocolAsPanel.ipf, Transmission.ipf 
    887889// 
    888 Function AttenuationFactor(fileStr,lam,attenNo) 
    889          
    890         // 
     890// atten_err is one std. deviation, passed back by reference 
     891Function AttenuationFactor(fileStr,lam,attenNo,atten_err) 
    891892        String fileStr // 
    892         Variable lam,attenNo 
     893        Variable lam,attenNo, &atten_err 
    893894         
    894895        Variable attenFactor=1 
     
    896897        // your code here        
    897898        attenFactor = LookupAtten(lam,attenNo) 
     899 
     900        // Change April 2011 - now returns error in atten trans 
     901        atten_err = 0 
    898902 
    899903        return(attenFactor) 
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