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Measuring Spin-Energy Correlations in Nuclear Fission
Measuring Spin-Energy Correlations in Nuclear Fission
상세정보
- 자료유형
- 학위논문 서양
- 최종처리일시
- 20250211153010
- ISBN
- 9798384044642
- DDC
- 539.7
- 저자명
- Giha, Nathan P.
- 서명/저자
- Measuring Spin-Energy Correlations in Nuclear Fission
- 발행사항
- [Sl] : University of Michigan, 2024
- 발행사항
- Ann Arbor : ProQuest Dissertations & Theses, 2024
- 형태사항
- 126 p
- 주기사항
- Source: Dissertations Abstracts International, Volume: 86-03, Section: B.
- 주기사항
- Advisor: Pozzi, Sara A.;Tovesson, Fredrik.
- 학위논문주기
- Thesis (Ph.D.)--University of Michigan, 2024.
- 초록/해제
- 요약Despite over eighty years of study since nuclear fission was discovered, important details of this nuclear process remain poorly understood. Among them is the mechanism by which fission fragments acquire substantial spins, or angular momenta, despite originating from a heavy nucleus that may start with no spin. Thanks to advances in computational models of fission, theorists and experimentalists have recently put forth renewed effort toward revealing this spin generation mechanism. A truly predictive model of fission-with the correct spin generation mechanism-would have far-reaching implications on our understanding of fission recycling in the r-process of nucleosynthesis and our ability to simulate fission neutron and γ-ray emission for nuclear safeguards and nonproliferation scenarios.This dissertation aims to measure correlations between the spin generated in the fission fragments and the energy available to them. Practically, we measure correlations between fission γ-ray emission and properties of the fragments that emit them. We first measure the γ-ray multiplicity and spectrum from 239Pu(n,f) as a function of incident neutron energy using the Chi-Nu liquid scintillator array at the Los Alamos Neutron Science Center. We then develop and characterize a specialized fission fragment detector that measures the fragments' kinetic energies and masses at Argonne National Laboratory. Loaded with a 252Cf(sf) source, We place that fragment detector inside Gammasphere, a high-resolution and high-granularity γ-ray spectrometer, to measure correlations between the kinetic energies of specific fragments and γ-ray spectra they emit. We leverage our knowledge of the fragments' nuclear level schemes to reconstruct their spin distributions as a function of energy for the first time. Focusing on 144Ba, we find its average spin to be insensitive to energy-inconsistent with predictions from solely statistical excitation of rotational modes in the fragments. We thus conclude that more complex modes of spin generation are at play in fission.We discuss the corpus of correlated fission measurements that are relevant to spin generation and show how our measurements fit into that collection. We suggest improvements to the presented experiments in case they are repeated in the future, as well as straightforward extensions to the analysis presented in the dissertation with the existing data sets. Finally, we propose future experiments and analyses that will unlock entirely new fragment initial conditions and measured quantities, respectively.
- 일반주제명
- Nuclear physics
- 일반주제명
- Nuclear engineering
- 일반주제명
- Physics
- 키워드
- Nuclear fission
- 키워드
- Angular momentum
- 키워드
- Kinetic energies
- 키워드
- Spectrometer
- 기타저자
- University of Michigan Nuclear Engineering & Radiological Sciences
- 기본자료저록
- Dissertations Abstracts International. 86-03B.
- 전자적 위치 및 접속
- 로그인 후 원문을 볼 수 있습니다.
MARC
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■00520250211153010
■006m o d
■007cr#unu||||||||
■020 ▼a9798384044642
■035 ▼a(MiAaPQ)AAI31631440
■035 ▼a(MiAaPQ)umichrackham005659
■040 ▼aMiAaPQ▼cMiAaPQ
■0820 ▼a539.7
■1001 ▼aGiha, Nathan P.
■24510▼aMeasuring Spin-Energy Correlations in Nuclear Fission
■260 ▼a[Sl]▼bUniversity of Michigan▼c2024
■260 1▼aAnn Arbor▼bProQuest Dissertations & Theses▼c2024
■300 ▼a126 p
■500 ▼aSource: Dissertations Abstracts International, Volume: 86-03, Section: B.
■500 ▼aAdvisor: Pozzi, Sara A.;Tovesson, Fredrik.
■5021 ▼aThesis (Ph.D.)--University of Michigan, 2024.
■520 ▼aDespite over eighty years of study since nuclear fission was discovered, important details of this nuclear process remain poorly understood. Among them is the mechanism by which fission fragments acquire substantial spins, or angular momenta, despite originating from a heavy nucleus that may start with no spin. Thanks to advances in computational models of fission, theorists and experimentalists have recently put forth renewed effort toward revealing this spin generation mechanism. A truly predictive model of fission-with the correct spin generation mechanism-would have far-reaching implications on our understanding of fission recycling in the r-process of nucleosynthesis and our ability to simulate fission neutron and γ-ray emission for nuclear safeguards and nonproliferation scenarios.This dissertation aims to measure correlations between the spin generated in the fission fragments and the energy available to them. Practically, we measure correlations between fission γ-ray emission and properties of the fragments that emit them. We first measure the γ-ray multiplicity and spectrum from 239Pu(n,f) as a function of incident neutron energy using the Chi-Nu liquid scintillator array at the Los Alamos Neutron Science Center. We then develop and characterize a specialized fission fragment detector that measures the fragments' kinetic energies and masses at Argonne National Laboratory. Loaded with a 252Cf(sf) source, We place that fragment detector inside Gammasphere, a high-resolution and high-granularity γ-ray spectrometer, to measure correlations between the kinetic energies of specific fragments and γ-ray spectra they emit. We leverage our knowledge of the fragments' nuclear level schemes to reconstruct their spin distributions as a function of energy for the first time. Focusing on 144Ba, we find its average spin to be insensitive to energy-inconsistent with predictions from solely statistical excitation of rotational modes in the fragments. We thus conclude that more complex modes of spin generation are at play in fission.We discuss the corpus of correlated fission measurements that are relevant to spin generation and show how our measurements fit into that collection. We suggest improvements to the presented experiments in case they are repeated in the future, as well as straightforward extensions to the analysis presented in the dissertation with the existing data sets. Finally, we propose future experiments and analyses that will unlock entirely new fragment initial conditions and measured quantities, respectively.
■590 ▼aSchool code: 0127.
■650 4▼aNuclear physics
■650 4▼aNuclear engineering
■650 4▼aPhysics
■653 ▼aNuclear fission
■653 ▼aAngular momentum
■653 ▼aSpin-energy correlations
■653 ▼aKinetic energies
■653 ▼aSpectrometer
■690 ▼a0756
■690 ▼a0552
■690 ▼a0605
■71020▼aUniversity of Michigan▼bNuclear Engineering & Radiological Sciences.
■7730 ▼tDissertations Abstracts International▼g86-03B.
■790 ▼a0127
■791 ▼aPh.D.
■792 ▼a2024
■793 ▼aEnglish
■85640▼uhttp://www.riss.kr/pdu/ddodLink.do?id=T17164499▼nKERIS▼z이 자료의 원문은 한국교육학술정보원에서 제공합니다.
