Opened 16 years ago

Closed 15 years ago

#10 closed feature (fixed)

Large angle correction to detector efficiency

Reported by: ajj Owned by: kline
Priority: major Milestone: SANSReduction_5.1_Release
Component: SANS Reduction Keywords:
Cc: Blocking:
Task:

Description

As described in Annie Brulet's recent paper, at large scattering angles,
the detector efficiency changes. This change in efficiency can not be
corrected by making detector senstivity measurements at each instrument
configuration, because the scattering from pleiglass or water is not
flat at high angles, and the scattering is no longer monochromatic, with
significant fraction of scattered neutrons having wavelength 1 A to 3 A.

The attached word document describes a simple algebraic fix that can be
added to the SANS IGOR data reduction. There are also detector
dependent parameters that may need to be added to the raw data headers.
Namely, attenuation constant for aluminum and absorption constant for
He(3).

From: http://rt.ncnr.nist.gov/Ticket/Display.html?id=760

Attachments (1)

det_eff_cor2.doc (114.0 KB) - added by ajj 16 years ago.
Memo Describing Correction to Detector at Large Scattering Angles

Download all attachments as: .zip

Change History (4)

Changed 16 years ago by ajj

Memo Describing Correction to Detector at Large Scattering Angles

comment:1 Changed 15 years ago by ajj

  • Component changed from Analysis to SANS Reduction

comment:2 Changed 15 years ago by srkline

  • Milestone set to SANSReduction_5.1_Release

comment:3 Changed 15 years ago by srkline

  • Resolution set to fixed
  • Status changed from new to closed

Done. Added to the DetCorr?() function in WorkFileUtils?.ipf.

The correction is applied as the data is added to a work file, in 2D form.

As per John's memo, the correction is very small, (=1 most everywhere) but up to a few percent at the very largest angles, and increases the measured value.

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