Kinematically complete measurements of three-body photodisintegration of $^3$He were performed at the High Intensity $\\gamma$-ray Source (HI$\\gamma$S) with nearly monoenergetic 15 MeV photons. The experiment relied on two-nucleon coincidence measurements in which the nucleons are emitted on opposite sides of the incident $\\gamma$-ray beam axis. The setup consisted of seven 10 cm long cylindrical gas targets pressurized near 4 atm with thin windows to allow low-energy charged particles to exit with acceptable energy loss. Charged particles were detected in silicon strip detectors with angular acceptance constrained by a collimator system. Neutrons were detected in arrays of liquid organic scintillator cells. Data for neutron-proton (np) coincidences were acquired in configurations which selectively include or exclude the np final state interaction. Measurements of proton-proton (pp) coincidences along the same kinematic locus containing the np final state interaction (FSI) were also taken in-situ. Products from the two-body reaction were used as a luminosity monitor. Theory predictions were propagated through a GEANT4 simulation of the experimental setup. There was good agreement between predictions and measurements in the vicinity of the collinear point in which a proton remains at rest as measured by np coincidences. The measured np FSI peak included additional low-energy neutrons not anticipated by the simulation, which are likely associated with intermediate neutron scattering. The np FSI peak was found to be underpredicted by about 20$\\%$. The pp coincidence data were consistently about 39$\\%$ above predictions.
","abstract_html":"<p>Kinematically complete measurements of three-body photodisintegration of 3He were performed at the High Intensity γ-ray Source (HIγS) with nearly monoenergetic 15 MeV photons. The experiment relied on two-nucleon coincidence measurements in which the nucleons are emitted on opposite sides of the incident γ-ray beam axis. The setup consisted of seven 10 cm long cylindrical gas targets pressurized near 4 atm with thin windows to allow low-energy charged particles to exit with acceptable energy loss. Charged particles were detected in silicon strip detectors with angular acceptance constrained by a collimator system. Neutrons were detected in arrays of liquid organic scintillator cells. Data for neutron-proton (np) coincidences were acquired in configurations which selectively include or exclude the np final state interaction. Measurements of proton-proton (pp) coincidences along the same kinematic locus containing the np final state interaction (FSI) were also taken in-situ. Products from the two-body reaction were used as a luminosity monitor. Theory predictions were propagated through a GEANT4 simulation of the experimental setup. There was good agreement between predictions and measurements in the vicinity of the collinear point in which a proton remains at rest as measured by np coincidences. The measured np FSI peak included additional low-energy neutrons not anticipated by the simulation, which are likely associated with intermediate neutron scattering. The np FSI peak was found to be underpredicted by about 20$\\%$. The pp coincidence data were consistently about 39$\\%$ above predictions.</p>","abstract_has_math":true,"creators":["Friesen, Forrest Quinn Lister"],"institution":null,"degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":["Howell, Calvin R."],"committee_chairs":[],"committee_members":[],"year":2019,"date_issued":"2019","date_published":"2019","updated_at":"2026-07-24T02:07:21Z","subjects":["Nuclear physics and radiation","Physics","Particle physics"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/10161/19842","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Howell, Calvin R."]},{"key":"dc:creator","label":"Author","values":["Friesen, Forrest Quinn Lister"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2020-01-27T16:52:20Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2020-12-31T09:17:09Z"]},{"key":"dc:date.issued","label":"Date","values":["2019"]},{"key":"dc:type","label":"Dc Type","values":["Dissertation"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Nuclear physics and radiation","Physics","Particle physics"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://hdl.handle.net/10161/19842"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Kinematically complete measurements of three-body photodisintegration of $^3$He were performed at the High Intensity $\\gamma$-ray Source (HI$\\gamma$S) with nearly monoenergetic 15 MeV photons. The experiment relied on two-nucleon coincidence measurements in which the nucleons are emitted on opposite sides of the incident $\\gamma$-ray beam axis. The setup consisted of seven 10 cm long cylindrical gas targets pressurized near 4 atm with thin windows to allow low-energy charged particles to exit with acceptable energy loss. Charged particles were detected in silicon strip detectors with angular acceptance constrained by a collimator system. Neutrons were detected in arrays of liquid organic scintillator cells. Data for neutron-proton (np) coincidences were acquired in configurations which selectively include or exclude the np final state interaction. Measurements of proton-proton (pp) coincidences along the same kinematic locus containing the np final state interaction (FSI) were also taken in-situ. Products from the two-body reaction were used as a luminosity monitor. Theory predictions were propagated through a GEANT4 simulation of the experimental setup. There was good agreement between predictions and measurements in the vicinity of the collinear point in which a proton remains at rest as measured by np coincidences. The measured np FSI peak included additional low-energy neutrons not anticipated by the simulation, which are likely associated with intermediate neutron scattering. The np FSI peak was found to be underpredicted by about 20$\\%$. The pp coincidence data were consistently about 39$\\%$ above predictions.
"]},{"key":"dc:title","label":"Title","values":["Exclusive Photodisintegration of 3He"]}]}],"canonical_facts":{"dc:contributor.advisor":["Howell, Calvin R."],"dc:creator":["Friesen, Forrest Quinn Lister"],"dc:date.accessioned":["2020-01-27T16:52:20Z"],"dc:date.available":["2020-12-31T09:17:09Z"],"dc:date.issued":["2019"],"dc:description.abstract":["Kinematically complete measurements of three-body photodisintegration of $^3$He were performed at the High Intensity $\\gamma$-ray Source (HI$\\gamma$S) with nearly monoenergetic 15 MeV photons. The experiment relied on two-nucleon coincidence measurements in which the nucleons are emitted on opposite sides of the incident $\\gamma$-ray beam axis. The setup consisted of seven 10 cm long cylindrical gas targets pressurized near 4 atm with thin windows to allow low-energy charged particles to exit with acceptable energy loss. Charged particles were detected in silicon strip detectors with angular acceptance constrained by a collimator system. Neutrons were detected in arrays of liquid organic scintillator cells. Data for neutron-proton (np) coincidences were acquired in configurations which selectively include or exclude the np final state interaction. Measurements of proton-proton (pp) coincidences along the same kinematic locus containing the np final state interaction (FSI) were also taken in-situ. Products from the two-body reaction were used as a luminosity monitor. Theory predictions were propagated through a GEANT4 simulation of the experimental setup. There was good agreement between predictions and measurements in the vicinity of the collinear point in which a proton remains at rest as measured by np coincidences. The measured np FSI peak included additional low-energy neutrons not anticipated by the simulation, which are likely associated with intermediate neutron scattering. The np FSI peak was found to be underpredicted by about 20$\\%$. The pp coincidence data were consistently about 39$\\%$ above predictions.
"],"dc:identifier.uri":["https://hdl.handle.net/10161/19842"],"dc:subject":["Nuclear physics and radiation","Physics","Particle physics"],"dc:title":["Exclusive Photodisintegration of 3He"],"dc:type":["Dissertation"]},"updated_at":"2026-07-24T02:07:21Z"}