{"id":{"repo_id":"trento","oai_identifier":"oai:iris.unitn.it:11572/367984"},"canonical_url":"https://search.dev.ndltd.org/etd/trento/oai:iris.unitn.it:11572/367984","repository":{"repo_id":"trento","name":"Università degli Studi di Trento","base_url":"https://iris.unitn.it/oai/request"},"display":{"title":"A torsion pendulum ground test of the LISA Pathfinder Free-fall mode","abstract":"The LISA Pathfinder geodesic explorer mission for gravitational wave astronomy aims to measure a residual differential acceleration noise approaching the femto-m/s^2/Hz^1/2 levels needed for eLISA. This measurement is complicated by a large, roughly nm/s^2, stable differential gravitational acceleration that must be actively compensated in order to hold the test particles centred inside an orbiting apparatus. The actuation force applied to compensate this effect introduces a dominant source of force noise in the mission noise budget. To suppress this noise source and avoid actuation instabilities, a “free-fall” actuation control scheme has been designed: actuation is limited to brief impulses, with test masses in free fall in between two “kicks”, with this actuation-free motion then analysed for the remaining sources of acceleration ultra noise. In this work, we present the results from an extensive on-ground torsion pendulum test of this free-fall technique, which to date allows an equivalent acceleration noise measurement at the 100 fm/s^2/sqrt(Hz), a factor 3 above the LISA Pathfinder spec. We will discuss both experimental and analysis limitations to the ground experiment and some implications for the flight test.","abstract_html":"The LISA Pathfinder geodesic explorer mission for gravitational wave astronomy aims to measure a residual differential acceleration noise approaching the femto-m/s^2/Hz^1/2 levels needed for eLISA. This measurement is complicated by a large, roughly nm/s^2, stable differential gravitational acceleration that must be actively compensated in order to hold the test particles centred inside an orbiting apparatus. The actuation force applied to compensate this effect introduces a dominant source of force noise in the mission noise budget. To suppress this noise source and avoid actuation instabilities, a “free-fall” actuation control scheme has been designed: actuation is limited to brief impulses, with test masses in free fall in between two “kicks”, with this actuation-free motion then analysed for the remaining sources of acceleration ultra noise. In this work, we present the results from an extensive on-ground torsion pendulum test of this free-fall technique, which to date allows an equivalent acceleration noise measurement at the 100 fm/s^2/sqrt(Hz), a factor 3 above the LISA Pathfinder spec. We will discuss both experimental and analysis limitations to the ground experiment and some implications for the flight test.","abstract_has_math":false,"creators":["Russano, Giuliana"],"institution":"Università degli studi di Trento","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2015,"date_issued":"2015","date_published":"2015","updated_at":"2026-07-24T05:04:15Z","subjects":["Settore FIS/05 - Astronomia e Astrofisica","Settore FIS/01 - Fisica Sperimentale"],"languages":["eng"],"rights":["info:eu-repo/semantics/openAccess","license:Tutti i diritti riservati (All rights reserved)"],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["http://dx.doi.org/10.15168/11572_367984","10.15168/11572_367984"],"render_values":[{"text":"http://dx.doi.org/10.15168/11572_367984","href":"http://dx.doi.org/10.15168/11572_367984","code":true},{"text":"10.15168/11572_367984","href":"https://doi.org/10.15168/11572_367984","code":true}]}]},"links":{"outbound_url":"https://hdl.handle.net/11572/367984","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Russano, Giuliana"]},{"key":"dc:creator","label":"Author","values":["Russano, Giuliana"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2015"]},{"key":"dc:publisher","label":"Institution","values":["Università degli studi di Trento","place:TRENTO"]},{"key":"dc:relation","label":"Dc Relation","values":["firstpage:1","lastpage:132","numberofpages:132"]},{"key":"dc:type","label":"Dc Type","values":["info:eu-repo/semantics/doctoralThesis"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Settore FIS/05 - Astronomia e Astrofisica","Settore FIS/01 - Fisica Sperimentale"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["eng"]},{"key":"dc:rights","label":"Dc Rights","values":["info:eu-repo/semantics/openAccess","license:Tutti i diritti riservati (All rights reserved)"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://hdl.handle.net/11572/367984","http://dx.doi.org/10.15168/11572_367984","10.15168/11572_367984"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["The LISA Pathfinder geodesic explorer mission for gravitational wave astronomy aims to measure a residual differential acceleration noise approaching the femto-m/s^2/Hz^1/2 levels needed for eLISA. This measurement is complicated by a large, roughly nm/s^2, stable differential gravitational acceleration that must be actively compensated in order to hold the test particles centred inside an orbiting apparatus. The actuation force applied to compensate this effect introduces a dominant source of force noise in the mission noise budget. To suppress this noise source and avoid actuation instabilities, a “free-fall” actuation control scheme has been designed: actuation is limited to brief impulses, with test masses in free fall in between two “kicks”, with this actuation-free motion then analysed for the remaining sources of acceleration ultra noise. In this work, we present the results from an extensive on-ground torsion pendulum test of this free-fall technique, which to date allows an equivalent acceleration noise measurement at the 100 fm/s^2/sqrt(Hz), a factor 3 above the LISA Pathfinder spec. We will discuss both experimental and analysis limitations to the ground experiment and some implications for the flight test."]},{"key":"dc:title","label":"Title","values":["A torsion pendulum ground test of the LISA Pathfinder Free-fall mode"]}]}],"canonical_facts":{"dc:contributor":["Russano, Giuliana"],"dc:creator":["Russano, Giuliana"],"dc:date":["2015"],"dc:description":["The LISA Pathfinder geodesic explorer mission for gravitational wave astronomy aims to measure a residual differential acceleration noise approaching the femto-m/s^2/Hz^1/2 levels needed for eLISA. This measurement is complicated by a large, roughly nm/s^2, stable differential gravitational acceleration that must be actively compensated in order to hold the test particles centred inside an orbiting apparatus. The actuation force applied to compensate this effect introduces a dominant source of force noise in the mission noise budget. To suppress this noise source and avoid actuation instabilities, a “free-fall” actuation control scheme has been designed: actuation is limited to brief impulses, with test masses in free fall in between two “kicks”, with this actuation-free motion then analysed for the remaining sources of acceleration ultra noise. In this work, we present the results from an extensive on-ground torsion pendulum test of this free-fall technique, which to date allows an equivalent acceleration noise measurement at the 100 fm/s^2/sqrt(Hz), a factor 3 above the LISA Pathfinder spec. We will discuss both experimental and analysis limitations to the ground experiment and some implications for the flight test."],"dc:identifier":["https://hdl.handle.net/11572/367984","http://dx.doi.org/10.15168/11572_367984","10.15168/11572_367984"],"dc:language":["eng"],"dc:publisher":["Università degli studi di Trento","place:TRENTO"],"dc:relation":["firstpage:1","lastpage:132","numberofpages:132"],"dc:rights":["info:eu-repo/semantics/openAccess","license:Tutti i diritti riservati (All rights reserved)"],"dc:subject":["Settore FIS/05 - Astronomia e Astrofisica","Settore FIS/01 - Fisica Sperimentale"],"dc:title":["A torsion pendulum ground test of the LISA Pathfinder Free-fall mode"],"dc:type":["info:eu-repo/semantics/doctoralThesis"]},"updated_at":"2026-07-24T05:04:15Z"}