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Longitudinal nuclear spin relaxation in ³HE gas at low temperatures Chapman, Ross
Abstract
The first measurements of the temperature dependence of the intrinsic dipolar relaxation time T[sub 1B] due to binary collisions in dilute ³HE gas are reported. Sufficiently pure experimental conditions to observe T[sub 1B] were prepared by coating bare pyrex sample cells with clean neon gas. The experiments are performed at low temperatures (1.7 K to 19.0 K) where the colliding atoms have very low energy, so the effect of the long-range attractive forces is strongly felt and the measurements are sensitive to the depth and nature of the helium attractive well. Calculations of T[sub 1B] using the best available helium potentials have been fitted to the experimental results to test the parameters which describe the potential. The data favours a potential of the Bruch-McGee form, but having a slightly deeper attractive well of 11.5 K. The experiment also probes the adsorbed phase of ³HE via wall relaxation. Both wall relaxation and bulk gas relaxation are present in all measurements, but they can be identified by their density dependence. Measurements of wall relaxation time T[sub 1W] have been made on strongly relaxing and weakly relaxing surfaces, and the field dependence has been studied between 0.5 kG and 9.3 kG at temperatures of 2.6 K, 4.2 K and 8.0 K. The results of the field dependence are interpreted in terms of a model which considers relaxation of ³HE atoms diffusing on a plane and interacting via the dipolar coupling.
Item Metadata
Title |
Longitudinal nuclear spin relaxation in ³HE gas at low temperatures
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
1975
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Description |
The first measurements of the temperature dependence of the intrinsic
dipolar relaxation time T[sub 1B] due to binary collisions in dilute ³HE gas
are reported. Sufficiently pure experimental conditions to observe
T[sub 1B] were prepared by coating bare pyrex sample cells with clean neon
gas. The experiments are performed at low temperatures (1.7 K to 19.0 K)
where the colliding atoms have very low energy, so the effect of the
long-range attractive forces is strongly felt and the measurements are
sensitive to the depth and nature of the helium attractive well.
Calculations of T[sub 1B] using the best available helium potentials have been
fitted to the experimental results to test the parameters which describe
the potential. The data favours a potential of the Bruch-McGee form,
but having a slightly deeper attractive well of 11.5 K.
The experiment also probes the adsorbed phase of ³HE via wall
relaxation. Both wall relaxation and bulk gas relaxation are present in
all measurements, but they can be identified by their density dependence.
Measurements of wall relaxation time T[sub 1W] have been made on strongly
relaxing and weakly relaxing surfaces, and the field dependence has
been studied between 0.5 kG and 9.3 kG at temperatures of 2.6 K, 4.2 K
and 8.0 K. The results of the field dependence are interpreted in terms
of a model which considers relaxation of ³HE atoms diffusing on a plane and interacting via the dipolar coupling.
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Genre | |
Type | |
Language |
eng
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Date Available |
2010-02-05
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0085159
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.