Q1D needs more data

[Steve Williams]

Correct Q1D to what Richard says here: Q1D NEEDS

Cross section = Sum{ counts at w in pixel } / sum{ M(w)eta(w)T(w)omega(pixel) }

NOT the present

Cross section = Sum{ counts/M(w)eta(w)T(w)} /Sum{ omega(pixel) }

w is wavelength, “sum” is over all pixels and time channels contributing to given Q, M(w) is monitor, eta(w) direct beam efficiency ratio, T(w) is the experimentally measured sample transmission, omega is pixel solid angle times some possible flood source correction factor.

Sorry this does not fit neatly into object oriented code, which was why we compromised in the first place, though it does make the error calculation simpler as the actual number of neutrons is kept in the numerator and you can just take its square root. I have ignored the sample volume rescaling above.

These means Q1D requires counts as function of wavelength with no pixel, or bin (wavelength) dependent corrections done to it. Other corrections, that effect all data equally are possible, for example correction by sample volume, before or after Q1D.

All pixel and bin dependent corrections must be done within Q1D so Q1D needs the monitor spectrum, transmission spectrum, detector efficency correction and flood (flat cell) file.

For each output value of Q the numerator and denominator of Richrd's Colette question above is formed as a sum. Once the two sums are complete the division takes place.

This will agree with what is here: http://www.mantidproject.org/Q1D

[Steve Williams]

(In [12386]) Optional (NULL) workspaces can now be included in PARALLEL_FOR macro statements, obviously a missing workspace shouldn't stop multithreading re #3105

[Steve Williams]

(In [12470]) A SANS Q1D algorithm that takes raw counts data and does all the normalization within itself. Not tested yet and the spectra detector map is certainly wrong re #3105

[Steve Williams]

(In [12474]) Fix build on Linux and Mac, fingers crossed re #3105

[Steve Williams]

(In [12475]) Disable tests until I can find a suitable run file in AutoTestData/ re #3105

[Steve Williams]

(In [12538]) Created Python objects for the new Q1D and ensured that the distribution statuses are correct as this is important for Q1D re #3105

[Steve Williams]

(In [12550]) Q1D now calculates the normalization term within itself re #3105

[Steve Williams]

(In [12551]) Q1D2Test needs to await more data on the servers re #3105

[Steve Williams]

(In [12554]) Revert the changes to Q1D while we do more testing re #3105

[Steve Williams]

(In [12557]) Will this fix the tests? re #3105

[Mathieu Doucet]

(In [12558]) Cleaning up fix to make python happy. Re #3105

[Steve Williams]

(In [12700]) Improvements to SANS Q1D normalization Python scripts to deal with reductions in loops re #3105

[Steve Williams]

(In [12717]) The SANS Q calculation can now work the old way, doing the normalization first re #3105

[Steve Williams]

(In [12744]) Test for the new Q1D version 2 re #3105

[Steve Williams]

(In [12814]) Q1D has been updated! re #3167 fixes #3105

[Mathieu Doucet]

This algorithm does what it's supposed to do.

[Stuart Campbell]

This ticket has been transferred to github issue ​3952