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Transverse Acoustic Measurements of ...

Collett, Charles Alward.

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Transverse Acoustic Measurements of Superuid Helium-3 at Fixed and Variable Path Lengths.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Transverse Acoustic Measurements of Superuid Helium-3 at Fixed and Variable Path Lengths./
Author:	Collett, Charles Alward.
Description:	150 p.
Notes:	Source: Dissertation Abstracts International, Volume: 77-02(E), Section: B.
Contained By:	Dissertation Abstracts International77-02B(E).
Subject:	Low temperature physics. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3724214
ISBN:	9781339076539

Transverse Acoustic Measurements of Superuid Helium-3 at Fixed and Variable Path Lengths.
Collett, Charles Alward.

Transverse Acoustic Measurements of Superuid Helium-3 at Fixed and Variable Path Lengths. - 150 p.

Source: Dissertation Abstracts International, Volume: 77-02(E), Section: B.

Thesis (Ph.D.)--Northwestern University, 2015.

This thesis describes experiments using transverse zero sound in pure superfluid 3He to probe excitations with energies below the superfluid gap. One main focus is on a collective mode of the order parameter, the imaginary squashing mode. The splitting of this mode in a magnetic field causes acoustic birefringence, which rotates the polarization axis of the transverse sound wave. We have made precise measurements of this rotation in magnetic fields up to 0.11 T and observed the onset of nonlinear field dependence. Our measurements of the linear field dependence disagree with theoretical predictions, which led us to discover that the theory only applies when the sound frequency is close to the mode frequency, a condition not satisfied in our experiments. We extrapolated our data to the region of validity of the theory, and measured attractive sub-dominant f-wave pairing interactions.

ISBN: 9781339076539Subjects--Topical Terms:

3173917
Low temperature physics.

Transverse Acoustic Measurements of Superuid Helium-3 at Fixed and Variable Path Lengths.
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020 $a 9781339076539
035 $a (MiAaPQ)AAI3724214
035 $a AAI3724214
040 $a MiAaPQ $c MiAaPQ
100 1 $a Collett, Charles Alward. $3 3193098
245 1 0 $a Transverse Acoustic Measurements of Superuid Helium-3 at Fixed and Variable Path Lengths.
300 $a 150 p.
500 $a Source: Dissertation Abstracts International, Volume: 77-02(E), Section: B.
500 $a Adviser: William P. Halperin.
502 $a Thesis (Ph.D.)--Northwestern University, 2015.
520 $a This thesis describes experiments using transverse zero sound in pure superfluid 3He to probe excitations with energies below the superfluid gap. One main focus is on a collective mode of the order parameter, the imaginary squashing mode. The splitting of this mode in a magnetic field causes acoustic birefringence, which rotates the polarization axis of the transverse sound wave. We have made precise measurements of this rotation in magnetic fields up to 0.11 T and observed the onset of nonlinear field dependence. Our measurements of the linear field dependence disagree with theoretical predictions, which led us to discover that the theory only applies when the sound frequency is close to the mode frequency, a condition not satisfied in our experiments. We extrapolated our data to the region of validity of the theory, and measured attractive sub-dominant f-wave pairing interactions.
520 $a The other main focus is the construction of an experimental apparatus to enable in situ variation of the acoustic cavity spacing at low temperatures. Recent measurements have indicated a coupling between the transverse sound attenuation and surface Andreev bound states, which are predicted to be Majorana states in the specular scattering limit. A variable path length sample cell would enable measurements of the absolute attenuation of transverse sound, as well as allow for the separation of bulk effects from surface effects. It would also enable experiments looking for transverse zero sound in the normal state of 3He, which is predicted to have a high attenuation length requiring a micron-scale acoustic cavity. We have designed and implemented a diaphragm-based variable path length cell, and discuss our current progress and future prospects.
590 $a School code: 0163.
650 4 $a Low temperature physics. $3 3173917
650 4 $a Condensed matter physics. $3 3173567
650 4 $a Physics. $3 516296
690 $a 0598
690 $a 0611
690 $a 0605
710 2 $a Northwestern University. $b Physics and Astronomy. $3 1035948
773 0 $t Dissertation Abstracts International $g 77-02B(E).
790 $a 0163
791 $a Ph.D.
792 $a 2015
793 $a English
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3724214