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- All Subjects: Nuclear physics and radiation
- Creators: Comfort, Joseph R.
Description
This work presents analysis and results for the NPDGamma experiment, measuring
the spin-correlated photon directional asymmetry in the $\vec{n}p\rightarrow
d\gamma$ radiative capture of polarized, cold neutrons on a parahydrogen
target. The parity-violating (PV) component of this asymmetry
$A_{\gamma,PV}$ is unambiguously related to the $\Delta I = 1$ component of
the hadronic weak interaction due to pion exchange. Measurements in the second
phase of NPDGamma were taken at the Oak Ridge National Laboratory (ORNL)
Spallation Neutron Source (SNS) from late 2012 to early 2014, and then again in
the first half of 2016 for an unprecedented level of statistics in order to
obtain a measurement that is precise with respect to theoretical predictions of
$A_{\gamma,PV}=O(10^{-8})$. Theoretical and experimental background,
description of the experimental apparatus, analysis methods, and results for
the high-statistics measurements are given.
the spin-correlated photon directional asymmetry in the $\vec{n}p\rightarrow
d\gamma$ radiative capture of polarized, cold neutrons on a parahydrogen
target. The parity-violating (PV) component of this asymmetry
$A_{\gamma,PV}$ is unambiguously related to the $\Delta I = 1$ component of
the hadronic weak interaction due to pion exchange. Measurements in the second
phase of NPDGamma were taken at the Oak Ridge National Laboratory (ORNL)
Spallation Neutron Source (SNS) from late 2012 to early 2014, and then again in
the first half of 2016 for an unprecedented level of statistics in order to
obtain a measurement that is precise with respect to theoretical predictions of
$A_{\gamma,PV}=O(10^{-8})$. Theoretical and experimental background,
description of the experimental apparatus, analysis methods, and results for
the high-statistics measurements are given.
ContributorsBlyth, David (Author) / Alarcon, Ricardo O (Thesis advisor) / Ritchie, Barry G. (Committee member) / Comfort, Joseph R. (Committee member) / Schmidt, Kevin E (Committee member) / Arizona State University (Publisher)
Created2017
Description
I describe the first continuous space nuclear path integral quantum Monte Carlo method, and calculate the ground state properties of light nuclei including Deuteron, Triton, Helium-3 and Helium-4, using both local chiral interaction up to next-to-next-to-leading-order and the Argonne $v_6'$ interaction. Compared with diffusion based quantum Monte Carlo methods such as Green's function Monte Carlo and auxiliary field diffusion Monte Carlo, path integral quantum Monte Carlo has the advantage that it can directly calculate the expectation value of operators without tradeoff, whether they commute with the Hamiltonian or not. For operators that commute with the Hamiltonian, e.g., the Hamiltonian itself, the path integral quantum Monte Carlo light-nuclei results agree with Green's function Monte Carlo and auxiliary field diffusion Monte Carlo results. For other operator expectations which are important to understand nuclear measurements but do not commute with the Hamiltonian and therefore cannot be accurately calculated by diffusion based quantum Monte Carlo methods without tradeoff, the path integral quantum Monte Carlo method gives reliable results. I show root-mean-square radii, one-particle number density distributions, and Euclidean response functions for single-nucleon couplings. I also systematically describe all the sampling algorithms used in this work, the strategies to make the computation efficient, the error estimations, and the details of the implementation of the code to perform calculations. This work can serve as a benchmark test for future calculations of larger nuclei or finite temperature nuclear matter using path integral quantum Monte Carlo.
ContributorsChen, Rong (Author) / Schmidt, Kevin E (Thesis advisor) / Alarcon, Ricardo O (Committee member) / Beckstein, Oliver (Committee member) / Comfort, Joseph R. (Committee member) / Shovkovy, Igor A. (Committee member) / Arizona State University (Publisher)
Created2020