SANS: Avoid warning messages from non assigned detectors

[mantid-builder]

sans_code
This issue was originally TRAC 6070

Original Reporter: Gesner Passos

Running a Reduce1D for the front detector of LOQ or even SANS2D, you will end up with the following warning message:

== Workspace index 698 (SpectrumIndex = 17085) has no detector assigned to it - discarding ==

The same message will be given for the following range of spectrum indexes: 16735:16736, 17085:17086, 17435:17436, 17785:17792.

By the definition of the HAB detector inside the LOQ_Definition_2012101-.xml file:

  `<idlist idname="HAB">`
    `<id start="16387" end="16734" />`
    `<id start="17087" end="17434" />`    
    `<id start="16737" end="17084" />`
    `<id start="17437" end="17784" />`
  `</idlist>`  

It follows that the spectrum indexes are not inside the HAB detector.
In fact, according to the user, those spectrums are related to detectors spares or not in use.

So, although the algorithm (Q1D) correctly warns the user that those spectrums are not assigned, it would be better not to pass to this algorithm those spectrums, so to avoid the warning message.

Maybe the workspace should be cropped in order not to pass by these invalid spectrums.

To reproduce this:

Open SANS interface, set the instrument to LOQ, load the user file attached [user_file.txt], set to batch mode and load the [for-test.csv]
and run 1D Reduce.

[mantid-builder]

Gesner Passos (2012-11-01T10:22:41):
CSV File for testing in batch mode

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@NickDraper (2013-01-28T09:23:18):
Moved at the code freeze for release 2.4

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@NickDraper (2013-04-29T09:49:52):
Moved to r2.6 at the end of r2.5

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@NickDraper (2013-07-26T13:55:00):
Moved to backlog at the code freeze for R2.6

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@NickDraper (2014-02-14T11:04:58):
Bulk move to assigned at the introduction of the triage step

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Gesner Passos (2014-03-06T09:18:26):
To test, move the user_file.txt to the systemtest/Data/LOQ. And load it from there.
The cycle is 12_3.

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Gesner Passos (2014-03-06T09:19:39):
User File

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Gesner Passos (2014-03-06T15:42:21):
These spectra are in the middle of the HAB detector. And Q1D uses the for loop:

for i in number of spectra: 
  get detector

It will be impossible to crop those spectra from the workspace that is given to Q1D. I think the best option here would be to add a parameter inside the LOQ instrument to

Have a hardcoded number of spectra that should be ignored. Or a parameter inside the IDF to tell to ignore some detectors not assigned.

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Gesner Passos (2014-03-06T15:43:34):
The file 6070.patch implements the option to add to idf a new parameter to ignore some spectra.

[mantid-builder]

http://trac.mantidproject.org/mantid/raw-attachment/ticket/6070/for-test.csv
(uploaded by Gesner Passos on 2012-11-01T10:22:41)

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http://trac.mantidproject.org/mantid/raw-attachment/ticket/6070/user_file.txt
(uploaded by Gesner Passos on 2014-03-06T09:19:39)

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http://trac.mantidproject.org/mantid/raw-attachment/ticket/6070/6070.patch
(uploaded by Gesner Passos on 2014-03-06T15:42:38)

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[Matthew-Andrew]

This is still an issue it seems like the best way to fix it would be to modify the LOQ IDF to ignore the problematic spectra as Gesnet mentions above. It is not an issue with the new Backend as this runs Q1D as a child algorithm so gets no output from it.

[gemmaguest]

Closing as this relates to the old backend