Measurement of proton and nitrogen polarization in ammonia and a test of equal spin temperature

Citation
B. Adeva et al., Measurement of proton and nitrogen polarization in ammonia and a test of equal spin temperature, NUCL INST A, 419(1), 1998, pp. 60-82
Citations number
42
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Spectroscopy /Instrumentation/Analytical Sciences","Instrumentation & Measurement
Journal title
NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT
ISSN journal
0168-9002 → ACNP
Volume
419
Issue
1
Year of publication
1998
Pages
60 - 82
Database
ISI
SICI code
0168-9002(199812)419:1<60:MOPANP>2.0.ZU;2-U
Abstract
The 1996 data taking of the SMC experiment used polarized protons to measur e the spin-dependent structure function g(1) of the proton. Three liters of solid granular ammonia were irradiated at the Bonn electron linac in order to create the paramagnetic radicals which are needed for polarizing the pr otons. Proton polarizations of +/- (90 +/- 2.5)% were routinely reached. An analysis based on a theoretical line shape for spin-1. systems with large quadrupolar broadening was developed which allowed the nitrogen polarizatio n in the ammonia to be determined with a 10% relative error. The measured q uadrupolar coupling constant of N-14 agrees well with earlier extrapolated values. The polarization of the nitrogen nuclei was measured as a function of the proton polarization in order to provide a test of the equal spin tem perature (EST) hypothesis. It was found to be closely valid under the dynam ic nuclear polarization conditions with which the protons are polarized. La rge deviations from EST could be induced by cross relaxing the proton and n itrogen spin systems at low fields. Nitrogen polarizations up to 40% were r eached by these means. (C) 1998 Elsevier Science B.V. All rights reserved.