- Title Information
- Title
- Electrons and Exotic Ions in Superfluid Helium-4
- Type of Resource (primo)
- dissertations
- Name:
Personal
- Name Part
- Xing, Yiming
- Role
- Role Term:
Text
- creator
- Name:
Personal
- Name Part
- Maris, Humphrey
- Role
- Role Term:
Text
- Advisor
- Name:
Personal
- Name Part
- Valles, James
- Role
- Role Term:
Text
- Reader
- Name:
Personal
- Name Part
- Seidel, George
- Role
- Role Term:
Text
- Reader
- Name:
Personal
- Name Part
- Guo, Wei
- Role
- Role Term:
Text
- Reader
- Name:
Corporate
- Name Part
- Brown University. Department of Physics
- Role
- Role Term:
Text
- sponsor
- Origin Information
- Copyright Date
- 2023
- Physical Description
- Extent
- xxiii, 147 p.
- digitalOrigin
- born digital
- Note:
thesis
- Thesis (Ph. D.)--Brown University, 2023
- Genre (aat)
- theses
- Abstract
- An electron in liquid helium repels helium atoms and forms a spherical cavity referred to as an “electron bubble.” In addition to this well-known normal electron bubble, mobility measurements have revealed the existence of a number of negative ions of unknown structure. These include the so-called “exotic ions,” and two others labeled as “A” and “B.” In this thesis we report our studies of different charge carriers in superfluid helium.
The stability of few-electron bubbles containing three and eight electrons was studied by computer simulations. The pressure ranges within which these bubbles are stable were determined.
A series of time-of-flight mobility measurements were performed to investigate negative and positive ions in liquid helium. First, the pressure dependences of the fast ion mobility and the He+ ion mobility were measured up to a pressure of 5.5 bars. The fast ion is the exotic ion that has the highest mobility. This measurement shows that the radius of the fast ion does not significantly vary with pressure. Next, multiple positive helium ions were observed. These ions have mobilities slightly different from that of the normal positive ion He+. Further, signals from the exotic ions were detected using an Am-241 alpha source to produce a plasma discharge in helium vapor. Moreover, experimental conditions under which the A and B ions occur were studied. Both of them have a continuous distribution of mobility. The A ions are interpreted as bubbles containing only a fraction of the single electron wave function. The simulation based on this interpretation is in reasonable agreement with the experimental results and supports the idea that liquid helium does not make a measurement to determine whether an electron is in the bubble. Other possible explanations are also discussed. Lastly, we describe experiments using a carbon dioxide laser to excite electron bubbles from the 1S state to the 1P state. Multiple current signals following the photo-excitation were detected, and possible origins of these signals were studied.
- Subject (fast)
(authorityURI="http://id.worldcat.org/fast", valueURI="http://id.worldcat.org/fast/01003163")
- Topic
- Low temperatures
- Subject (fast)
(authorityURI="http://id.worldcat.org/fast", valueURI="http://id.worldcat.org/fast/00999579")
- Topic
- Liquid helium
- Subject (fast)
(authorityURI="http://id.worldcat.org/fast", valueURI="http://id.worldcat.org/fast/01138874")
- Topic
- Superfluidity
- Language
- Language Term (ISO639-2B)
- English
- Record Information
- Record Content Source (marcorg)
- RPB
- Record Creation Date
(encoding="iso8601")
- 20230602