{"id":{"repo_id":"lancaster","oai_identifier":"oai:eprints.lancs.ac.uk:83024"},"canonical_url":"https://search.dev.ndltd.org/etd/lancaster/oai:eprints.lancs.ac.uk:83024","repository":{"repo_id":"lancaster","name":"Lancaster University","base_url":"https://eprints.lancs.ac.uk/cgi/oai2"},"display":{"title":"Quasiparticle beam profile measurements in superfluid helium 3 - B","abstract":"This thesis details experiments in the ballistic regime of superfluid 3He-B at temperatures around 100 ➭K. In this thesis, the quasiparticle beam profile from a Black-Body radiator and a vibrating wire resonator is measured using a quasiparticle camera which consists of 25 tuning forks. The vibrating wire resonator is found to have a very thinly spread beam at velocities slightly higher than the pair-breaking critical velocity which spreads out at higher velocities. At 21 mm/s the vibrating resonator is found to have a more focused beam than the Black-Body radiator where both beam profiles are found to be focused around the centre of the quasiparticle camera. A theoretical model is created in order to model the spread and intensity of the experimental beam profile from the Black-Body radiator. In this thesis, the response of some of the probes to thermal damping is measured in the form of the geometrical constants γ and λ. The geometrical constant λ is related to the velocity dependence of the probe to thermal damping and is found for two wires of varying diameter, a tuning fork and its overtone mode in which all the values of λ were close to unity. The geometrical constant γ is related to the sensitivity of a probe to thermal damping. This is found for a Black-Body radiator and then used to derive the sensitivity for other wires in the cell in thermal equilibrium with it. Two resonant modes of a small tuning fork are used to do a Black-Body radiator calibration on the area around the tuning fork which is used to find the sensitivity of 25 tuning forks (pixels) in the quasiparticle camera.","abstract_html":"This thesis details experiments in the ballistic regime of superfluid 3He-B at temperatures around 100 ➭K. In this thesis, the quasiparticle beam profile from a Black-Body radiator and a vibrating wire resonator is measured using a quasiparticle camera which consists of 25 tuning forks. The vibrating wire resonator is found to have a very thinly spread beam at velocities slightly higher than the pair-breaking critical velocity which spreads out at higher velocities. At 21 mm/s the vibrating resonator is found to have a more focused beam than the Black-Body radiator where both beam profiles are found to be focused around the centre of the quasiparticle camera. A theoretical model is created in order to model the spread and intensity of the experimental beam profile from the Black-Body radiator. In this thesis, the response of some of the probes to thermal damping is measured in the form of the geometrical constants γ and λ. The geometrical constant λ is related to the velocity dependence of the probe to thermal damping and is found for two wires of varying diameter, a tuning fork and its overtone mode in which all the values of λ were close to unity. The geometrical constant γ is related to the sensitivity of a probe to thermal damping. This is found for a Black-Body radiator and then used to derive the sensitivity for other wires in the cell in thermal equilibrium with it. Two resonant modes of a small tuning fork are used to do a Black-Body radiator calibration on the area around the tuning fork which is used to find the sensitivity of 25 tuning forks (pixels) in the quasiparticle camera.","abstract_has_math":false,"creators":["Ahlstrom, Sean","Fisher, Shaun","Tsepelin, Viktor"],"institution":"Lancaster University","degree_name":"Ph.D.","degree_level":"doctoral","degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2016,"date_issued":"2016-11","date_published":"2016-11","updated_at":"2026-07-24T02:48:32Z","subjects":[],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":null,"outbound_label":null,"outbound_source":null},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Ahlstrom, Sean","Fisher, Shaun","Tsepelin, Viktor"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2016-11-18"]},{"key":"dc:date.issued","label":"Date","values":["2016-11"]},{"key":"dc:publisher.commercial","label":"Dc Publisher Commercial","values":["Lancaster University"]},{"key":"dc:publisher.department","label":"Dc Publisher Department","values":["Physics"]},{"key":"dc:publisher.institution","label":"Dc Publisher Institution","values":["Lancaster University"]},{"key":"dc:relation.isreferencedby","label":"Dc Relation Isreferencedby","values":["https://eprints.lancs.ac.uk/id/eprint/83024/"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"dc:type.qualificationlevel","label":"Dc Type Qualificationlevel","values":["doctoral"]},{"key":"dc:type.qualificationname","label":"Dc Type Qualificationname","values":["Ph.D."]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://eprints.lancs.ac.uk/id/eprint/83024/1/2016SeanLeeAhlstromPhD.pdf"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["This thesis details experiments in the ballistic regime of superfluid 3He-B at temperatures around 100 ➭K. In this thesis, the quasiparticle beam profile from a Black-Body radiator and a vibrating wire resonator is measured using a quasiparticle camera which consists of 25 tuning forks. The vibrating wire resonator is found to have a very thinly spread beam at velocities slightly higher than the pair-breaking critical velocity which spreads out at higher velocities. At 21 mm/s the vibrating resonator is found to have a more focused beam than the Black-Body radiator where both beam profiles are found to be focused around the centre of the quasiparticle camera. A theoretical model is created in order to model the spread and intensity of the experimental beam profile from the Black-Body radiator. In this thesis, the response of some of the probes to thermal damping is measured in the form of the geometrical constants γ and λ. The geometrical constant λ is related to the velocity dependence of the probe to thermal damping and is found for two wires of varying diameter, a tuning fork and its overtone mode in which all the values of λ were close to unity. The geometrical constant γ is related to the sensitivity of a probe to thermal damping. This is found for a Black-Body radiator and then used to derive the sensitivity for other wires in the cell in thermal equilibrium with it. Two resonant modes of a small tuning fork are used to do a Black-Body radiator calibration on the area around the tuning fork which is used to find the sensitivity of 25 tuning forks (pixels) in the quasiparticle camera."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Quasiparticle beam profile measurements in superfluid helium 3 - B"]}]}],"canonical_facts":{"dc:creator":["Ahlstrom, Sean","Fisher, Shaun","Tsepelin, Viktor"],"dc:date":["2016-11-18"],"dc:date.issued":["2016-11"],"dc:description.abstract":["This thesis details experiments in the ballistic regime of superfluid 3He-B at temperatures around 100 ➭K. In this thesis, the quasiparticle beam profile from a Black-Body radiator and a vibrating wire resonator is measured using a quasiparticle camera which consists of 25 tuning forks. The vibrating wire resonator is found to have a very thinly spread beam at velocities slightly higher than the pair-breaking critical velocity which spreads out at higher velocities. At 21 mm/s the vibrating resonator is found to have a more focused beam than the Black-Body radiator where both beam profiles are found to be focused around the centre of the quasiparticle camera. A theoretical model is created in order to model the spread and intensity of the experimental beam profile from the Black-Body radiator. In this thesis, the response of some of the probes to thermal damping is measured in the form of the geometrical constants γ and λ. The geometrical constant λ is related to the velocity dependence of the probe to thermal damping and is found for two wires of varying diameter, a tuning fork and its overtone mode in which all the values of λ were close to unity. The geometrical constant γ is related to the sensitivity of a probe to thermal damping. This is found for a Black-Body radiator and then used to derive the sensitivity for other wires in the cell in thermal equilibrium with it. Two resonant modes of a small tuning fork are used to do a Black-Body radiator calibration on the area around the tuning fork which is used to find the sensitivity of 25 tuning forks (pixels) in the quasiparticle camera."],"dc:format":["application/pdf"],"dc:identifier.uri":["https://eprints.lancs.ac.uk/id/eprint/83024/1/2016SeanLeeAhlstromPhD.pdf"],"dc:publisher.commercial":["Lancaster University"],"dc:publisher.department":["Physics"],"dc:publisher.institution":["Lancaster University"],"dc:relation.isreferencedby":["https://eprints.lancs.ac.uk/id/eprint/83024/"],"dc:title":["Quasiparticle beam profile measurements in superfluid helium 3 - B"],"dc:type":["Thesis"],"dc:type.qualificationlevel":["doctoral"],"dc:type.qualificationname":["Ph.D."]},"updated_at":"2026-07-24T02:48:32Z"}