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THE SECONDARY EXTINCTION CORRECTION

Abstract

It is shown that Darwin's formula for the secondary extinction correction, which has been universally accepted and extensively used, contains an appreciable error in the x-ray diffraction case. The correct formula is derived. As a first order correction for secondary extinction, Darwin showed that one should use an effective absorption coefficient mu + gQ where an unpolarized incident beam is presumed. The new derivation shows that the effective absorption coefficient is mu + 2gQ(1 + cos/sup 4/2 theta )/(1 plus or minus cos/sup 2/2 theta )/s up 2/, which gives mu + gQ at theta =0 deg and theta = 90 deg , but mu + 2gQ at theta = 45 deg . Darwin's theory remains valid when applied to neutron diffraction. (auth)
Publication Date:
Mar 15, 1963
Product Type:
Conference
Report Number:
CONF-64-2; AED-Conf-63-053-3
Reference Number:
NSA-17-032829
Resource Relation:
Conference: American Cyrstallographic Assn. Meeting, Cambridge, MA (United States), 28-30 Mar 1963
Subject:
PHYSICS; ABSORPTION; ANGULAR DISTRIBUTION; BEAMS; DIFFRACTION; EQUATIONS; ERRORS; NEUTRONS; NUMERICALS; REFRACTION; X RADIATION
Sponsoring Organizations:
Sponsor not identified
OSTI ID:
4875506
Research Organizations:
Univ. of Chicago, IL (United States)
Country of Origin:
United States
Language:
English
Submitting Site:
DTIE
Size:
Pages: 21
Announcement Date:
Jul 20, 2013

Citation Formats

Zachariasen, W. H. THE SECONDARY EXTINCTION CORRECTION. United States: N. p., 1963. Web.
Zachariasen, W. H. THE SECONDARY EXTINCTION CORRECTION. United States.
Zachariasen, W. H. 1963. "THE SECONDARY EXTINCTION CORRECTION." United States.
@misc{etde_4875506,
title = {THE SECONDARY EXTINCTION CORRECTION}
author = {Zachariasen, W. H.}
abstractNote = {It is shown that Darwin's formula for the secondary extinction correction, which has been universally accepted and extensively used, contains an appreciable error in the x-ray diffraction case. The correct formula is derived. As a first order correction for secondary extinction, Darwin showed that one should use an effective absorption coefficient mu + gQ where an unpolarized incident beam is presumed. The new derivation shows that the effective absorption coefficient is mu + 2gQ(1 + cos/sup 4/2 theta )/(1 plus or minus cos/sup 2/2 theta )/s up 2/, which gives mu + gQ at theta =0 deg and theta = 90 deg , but mu + 2gQ at theta = 45 deg . Darwin's theory remains valid when applied to neutron diffraction. (auth)}
place = {United States}
year = {1963}
month = {Mar}
}