\"Atomic Collision experiments are best suited to sensitively test the few-body dynamics of simple systems. The few-body dynamics, in turn, can be sensitively affected by interference effects. However, an important requirement to observe interference effects in atomic scattering experiments is that the incoming projectile beam must be coherent. The coherence properties of the incoming projectile can be controlled by the geometry of the collimating slit placed before the target. We performed a kinematically complete experiment where a 75 keV proton beam is crossed with a molecular hydrogen beam to study the dissociative capture process. The motivation for this project was to explain a π-phase shift found in the interference pattern observed in a previous experiment. To this end the recoil-ion momentum resolution was improved by a factor of 5 and the statistics by an order of magnitude. As a result, we got a pronounced interference pattern in the FDCS as compared to previous data. The differential cross-section in KER showed that the phase shift is not constant at π, but rather changes with θp. It is π for relatively small θp, almost 0 for large θp, and is independent of the KER. In another project we studied p + He collisions to extract the incoherent cross section very close to the velocity matching regime. While in a previous experiment with a coherent beam a double peak structure was observed, we expected a single peak structure in the FDCS in the current experiment. The double peak structure in the coherent case (past experiment) was explained as an interference structure between first and higher order interactions (one of which is PCI). This interpretation is indeed supported by our observation of only a single peak in the incoherent case. It is further supported, at least qualitatively, by a theoretical calculation\"--Abstract, page iv.
","abstract_html":"<p>"Atomic Collision experiments are best suited to sensitively test the few-body dynamics of simple systems. The few-body dynamics, in turn, can be sensitively affected by interference effects. However, an important requirement to observe interference effects in atomic scattering experiments is that the incoming projectile beam must be coherent. The coherence properties of the incoming projectile can be controlled by the geometry of the collimating slit placed before the target. We performed a kinematically complete experiment where a 75 keV proton beam is crossed with a molecular hydrogen beam to study the dissociative capture process. The motivation for this project was to explain a π-phase shift found in the interference pattern observed in a previous experiment. To this end the recoil-ion momentum resolution was improved by a factor of 5 and the statistics by an order of magnitude. As a result, we got a pronounced interference pattern in the FDCS as compared to previous data. The differential cross-section in KER showed that the phase shift is not constant at π, but rather changes with θ<sub>p</sub>. It is π for relatively small θ<sub>p</sub>, almost 0 for large θ<sub>p</sub>, and is independent of the KER. In another project we studied p + He collisions to extract the incoherent cross section very close to the velocity matching regime. While in a previous experiment with a coherent beam a double peak structure was observed, we expected a single peak structure in the FDCS in the current experiment. The double peak structure in the coherent case (past experiment) was explained as an interference structure between first and higher order interactions (one of which is PCI). This interpretation is indeed supported by our observation of only a single peak in the incoherent case. It is further supported, at least qualitatively, by a theoretical calculation"--Abstract, page iv.</p>","abstract_has_math":false,"creators":["Bastola, Sujan"],"institution":"Missouri University of Science and Technology","degree_name":"Ph. D. in Physics","degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":null,"date_issued":"","date_published":null,"updated_at":"2026-07-24T03:18:18Z","subjects":["Atomic physics","Atomic, Molecular and Optical Physics"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://scholarsmine.mst.edu/doctoral_dissertations/3165","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Bastola, Sujan"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:type","label":"Dc Type","values":["Dissertation - Open Access"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph. D. in Physics"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Missouri University of Science and Technology"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Atomic physics","Atomic, Molecular and Optical Physics"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://scholarsmine.mst.edu/doctoral_dissertations/3165"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["\"Atomic Collision experiments are best suited to sensitively test the few-body dynamics of simple systems. The few-body dynamics, in turn, can be sensitively affected by interference effects. However, an important requirement to observe interference effects in atomic scattering experiments is that the incoming projectile beam must be coherent. The coherence properties of the incoming projectile can be controlled by the geometry of the collimating slit placed before the target. We performed a kinematically complete experiment where a 75 keV proton beam is crossed with a molecular hydrogen beam to study the dissociative capture process. The motivation for this project was to explain a π-phase shift found in the interference pattern observed in a previous experiment. To this end the recoil-ion momentum resolution was improved by a factor of 5 and the statistics by an order of magnitude. As a result, we got a pronounced interference pattern in the FDCS as compared to previous data. The differential cross-section in KER showed that the phase shift is not constant at π, but rather changes with θp. It is π for relatively small θp, almost 0 for large θp, and is independent of the KER. In another project we studied p + He collisions to extract the incoherent cross section very close to the velocity matching regime. While in a previous experiment with a coherent beam a double peak structure was observed, we expected a single peak structure in the FDCS in the current experiment. The double peak structure in the coherent case (past experiment) was explained as an interference structure between first and higher order interactions (one of which is PCI). This interpretation is indeed supported by our observation of only a single peak in the incoherent case. It is further supported, at least qualitatively, by a theoretical calculation\"--Abstract, page iv.
"]},{"key":"dc:title","label":"Title","values":["Using coherence and interference to study the few body dynamics in simple atomic collisions systems"]}]}],"canonical_facts":{"dc:creator":["Bastola, Sujan"],"dc:description.abstract":["\"Atomic Collision experiments are best suited to sensitively test the few-body dynamics of simple systems. The few-body dynamics, in turn, can be sensitively affected by interference effects. However, an important requirement to observe interference effects in atomic scattering experiments is that the incoming projectile beam must be coherent. The coherence properties of the incoming projectile can be controlled by the geometry of the collimating slit placed before the target. We performed a kinematically complete experiment where a 75 keV proton beam is crossed with a molecular hydrogen beam to study the dissociative capture process. The motivation for this project was to explain a π-phase shift found in the interference pattern observed in a previous experiment. To this end the recoil-ion momentum resolution was improved by a factor of 5 and the statistics by an order of magnitude. As a result, we got a pronounced interference pattern in the FDCS as compared to previous data. The differential cross-section in KER showed that the phase shift is not constant at π, but rather changes with θp. It is π for relatively small θp, almost 0 for large θp, and is independent of the KER. In another project we studied p + He collisions to extract the incoherent cross section very close to the velocity matching regime. While in a previous experiment with a coherent beam a double peak structure was observed, we expected a single peak structure in the FDCS in the current experiment. The double peak structure in the coherent case (past experiment) was explained as an interference structure between first and higher order interactions (one of which is PCI). This interpretation is indeed supported by our observation of only a single peak in the incoherent case. It is further supported, at least qualitatively, by a theoretical calculation\"--Abstract, page iv.
"],"dc:identifier":["https://scholarsmine.mst.edu/doctoral_dissertations/3165"],"dc:subject":["Atomic physics","Atomic, Molecular and Optical Physics"],"dc:title":["Using coherence and interference to study the few body dynamics in simple atomic collisions systems"],"dc:type":["Dissertation - Open Access"],"thesis:degree_name":["Ph. D. in Physics"],"thesis:institution_name":["Missouri University of Science and Technology"]},"updated_at":"2026-07-24T03:18:18Z"}