Page 1 |
Save page Remove page | Previous | 1 of 144 | Next |
|
small (250x250 max)
medium (500x500 max)
large ( > 500x500)
Full Resolution
All (PDF)
|
This page
All
Subset |
LOW FIELD STUDY OF A-LIKE PHASE FOR SUPERFLUID 3HE IN AEROGEL
by
Yuliang Du
A Dissertation Presented to the
FACULTY OF THE GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
DOCTOR OF PHILOSOPHY
(PHYSICS)
August 2009
Copyright 2009 Yuliang Du
Object Description
| Title | Low field study of A-like phase for superfluid 3He in aerogel |
| Author | Du, Yuliang |
| Author email | yuliang@usc.edu; microsystem.ca@gmail.com |
| Degree | Doctor of Philosophy |
| Document type | Dissertation |
| Degree program | Physics |
| School | College of Letters, Arts and Sciences |
| Date defended/completed | 2009-05-08 |
| Date submitted | 2009 |
| Restricted until | Unrestricted |
| Date published | 2009-08-09 |
| Advisor (committee chair) | Bozler, Hans |
| Advisor (committee member) |
Gould, Christopher Haas, Stephan Thompson, Richard Kim, Eun Sok |
| Abstract | Longitudinal and transverse DC-SQUID NMR experiments have been carried out to study the A-like phase of the superfluid 3He in the presence of aerogel scattering. Because the wide spectral line width of the scattered 3He A-like signals, the longitudinal response can not be identified from the background noise in the current experimental setup. The Fermi liquid to 3He A-like phase transition temperature Tc,aero have been inferred from the transverse NMR data only. Different from the previous 3He in aerogel experiments, which have mainly focused on the high field transverse NMR studies of the order parameter, the current low field NMR study gives a better physical picture of the impurity scattering effect on the superfluid order parameter. The field scaling measurement of the A-like phase frequency shift is carried out for the static H0 field at 10.31, 20.44 and 40.12 Gauss with the superfluid pressurized at 27.58 bar. For magnetic fields at 20.44 and 40.12 Gauss, the aerogel signal shifting away from the Larmor frequency is easily identified from the data analysis. But for magnetic field at 10.31 Gauss, the signal is much less visible in the FFT spectrum. Several DSP algorithms, including Morlet wavelet, Welch periodogram and Wiener analysis, have been carried out to further investigate the time-frequency response of the signal.; The 3He superfluid magnetic response is taken with 3 monolayers of 4He coated on the nominal 99.7% porosity aerogel strands. The purpose of the 4He preplating is to eliminate the fast exchange interactions between the superfluid and localized magnetic moments due to the 3He atoms deposited on the surface. The results from the bulk A phase transition are used to determine the absolute temperature scales for the experiment. A least square fit to the real time data is used to extract the normal fluid magnetic responses. Afterwards, the 3He superfluid A-like signal due to the presence of aerogel impurities is analyzed to determine the Tc,aero at 27.58 bar. The suppression of the superfluid order parameter is compared to the experimental results at high fields from other groups. |
| Keyword | NMR; A-like phase; superfluid 3He; aerogel; quantum fluid; order parameter; phase transition |
| Language | English |
| Part of collection | University of Southern California dissertations and theses |
| Publisher (of the original version) | University of Southern California |
| Place of publication (of the original version) | Los Angeles, California |
| Publisher (of the digital version) | University of Southern California. Libraries |
| Provenance | Electronically uploaded by the author |
| Type | texts |
| Legacy record ID | usctheses-m2556 |
| Rights | Du, Yuliang |
| Repository name | Libraries, University of Southern California |
| Repository address | Los Angeles, California |
| Repository email | http://www.usc.edu/isd/libraries/services/ask_a_librarian/email/ |
| Filename | etd-Du-2789 |
| Archival file | uscthesesreloadpub_Volume48/etd-Du-2789.pdf |
Description
| Title | Page 1 |
| Full text | LOW FIELD STUDY OF A-LIKE PHASE FOR SUPERFLUID 3HE IN AEROGEL by Yuliang Du A Dissertation Presented to the FACULTY OF THE GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY (PHYSICS) August 2009 Copyright 2009 Yuliang Du |
Comments
Post a Comment for Page 1
