Digital Commons Network^™

Estimation Of Methyl Orange Dye's Molar Absorptivity Using A Photoresistor-Based Photometer, Patricia M. Ludovice, Ramon M. Delos Santos

Physics Faculty Publications

The need to further develop solar cell technology, particularly on dye-sensitized solar cells (DSSCs), drives absorption studies of various chemical species. In this study, absorbance analysis of methyl orange (MO) dye was performed using the adapted and modified photoresistor-based photometer of Adams-McNichol et al. [1]. The research aims to improve the stability of the reference setup, while maintaining the accuracy of absorbance results it yields. The methodology includes photometer fabrication, MO dye sample preparation, and the evaluation of MO dye's molar absorptivity in an aqueous solution. Results show that the estimated molar absorptivity of MO using the voltage readings from …

Advancements In Nuclear Magnetic Resonance, Electron Paramagnetic Resonance, Multipole Moments, And Lie Group Proprieties, Zhichen Liu

Graduate Thesis and Dissertation 2023-2024

To accurately solve the general nuclear spin state function in Nuclear Magnetic Resonance (NMR), a rotation wave approach was employed, allowing the reference frame to rotate in sync with the oscillating magnetic field. The spin state system was analogously treated as a Rubik's Cube, ensuring the diagonalization of only the time-dependent part of the state function. Although Gottfried's equation (1966) aligns with transitions between specific spin states m and m′, his second rotation contradicts the conservation of angular momentum, resulting in inaccuracies for spin states with initial phase shifts or entangled states. Contrarily, Schwinger (1937) efficiently computed the coefficients for …

Snow Spheres And Ice Cubes, John Adam

Mathematics & Statistics Faculty Publications

This article, titled "Snow spheres and ice cubes," discusses the melting of snowballs and ice cubes. It explains that in standard calculus textbooks, it is shown that a snowball melting at a rate proportional to its surface area will have its radius decrease at a constant rate, assuming it remains spherical as it melts. The article then poses several questions related to this concept, including the proportion of a smaller snow sphere that remains when half of a larger one has melted, the value of p for which the smaller sphere first melts, and the volume reduction factor for cubes …

Preface, Mohamed Mahdi Tekitek, Manfred Krafczyk, Li-Shi Luo

Mathematics & Statistics Faculty Publications

[Introduction] Matter, conceptually classified into fluids and solids, can be completely described by the microscopic physics of its constituent atoms or molecules. However, for most engineering applications, a macroscopic or continuum description has usually been sufficient due to the large disparity between the spatial and temporal scales relevant to these applications and the scales of the underlying molecular dynamics. In this case, the microscopic physics merely determines material properties such as the viscosity of a fluid or the elastic constants of a solid. These material properties cannot be derived within the macroscopic framework, but the qualitative nature of the macroscopic …

Conventions, Definitions, Identities, And Other Useful Formulae, Robert A. Mcnees Iv

Physics: Faculty Publications and Other Works

As the name suggests, these notes contain a summary of important conventions, definitions, identities, and various formulas that I often refer to. They may prove useful for researchers working in General Relativity, Supergravity, String Theory, Cosmology, and related areas.

Complexity, Entanglement And Codes In Quantum Field Theory, Nikolaos Angelinos

Theses and Dissertations--Physics and Astronomy

In recent decades many deep connections between quantum information theory and quantum field theory have been unearthed. In this dissertation we study topics in high-energy physics through the lens of quantum information: 1) We develop connections between error-correcting codes and Narain conformal field theories. 2) We study the entanglement entropy of one-dimensional fermionic chains with long-range interactions. 3) We study the temperature dependence of Lanczos coefficients and Krylov complexity.

Topics In Quantum Information, Complexity And Chaos, Debarghya Chakraborty

Theses and Dissertations--Physics and Astronomy

This dissertation explores quantum information, the use of codes to describe quantum field theories, and introduces new concepts to characterize the dynamics of quantum many-body systems. The contributions of this dissertation are the following: 1) We constructed Narain Conformal Field Theories (CFTs) using additive codes, where the modular bootstrap constraints translate into algebraic conditions on the codes, extending previous approaches. This helps express key CFT data, including the torus partition function, in terms of codewords. We constructed optimal Narain CFTs for small central charges, and described CFT ensembles for asymptotically large central charge with large spectral gap. 2) We studied …

การศึกษาความเป็นไปได้ในการประยุกต์ใช้น้ำเสียที่ผ่านการบำบัดในกระบวนการอบยาง, สิรวิชญ์ โพธิ์ระหง

Chulalongkorn University Theses and Dissertations (Chula ETD)

บริษัท สยามมิชลิน จำกัด (โรงงานพระประแดง) จังหวัดสมุทรปราการ มุ่งมั่นในการจัดการทรัพยากรน้ำอย่างมีประสิทธิภาพและยั่งยืนในกระบวนการผลิตยางรถยนต์ การผลิตยางรถยนต์และยางรถจักรยานยนต์มีการใช้น้ำจำนวนมากในกระบวนการผลิต จึงเป็นเหตุให้เกิดน้ำเสียจำนวนมากตามมาเช่นกัน น้ำเสียเหล่านี้จะถูกส่งเข้าระบบบำบัดน้ำเสียแบบเลี้ยงตะกอนเร่งเพื่อบำบัดและมีสมบัติได้ตามมาตรฐานน้ำทิ้ง แนวทางในการลดการปล่อยน้ำเสียหลังการบำบัดแล้วสู่สาธารณะ คือ การนำน้ำเสียที่ผ่านการบำบัดเหล่านี้กลับมาใช้เพื่อสามารถหมุนเวียนทรัพยากรให้กลับมาใช้ใหม่อย่างมีประสิทธิภาพสูงสุด และยังสอดคล้องกับแผนการบริหารด้านความยั่งยืนในการจัดการสิ่งแวดล้อมของบริษัทอีกทางหนึ่งด้วย ในงานวิจัยนี้จึงศึกษาความเป็นไปได้ในการนำน้ำเสียที่ผ่านการบำบัดแล้วกลับมาใช้ใหม่ในกระบวนการอบยาง โดยศึกษาและปรับปรุงประสิทธิภาพอัตราการไฟล (%Recovery) ของระบบรีไซเคิลรีเวอร์สออสโมซิสแบบขั้นตอนเดียวด้วยสารกรองแก้ว (AFM®ng) พบว่ามีประสิทธิภาพเพิ่มขึ้นจากเป็นร้อยละ 64 จากนั้นศึกษาเปรียบเทียบความเป็นไปได้ของโครงการระหว่างระบบรีไซเคิลแบบสองขั้นตอน (Double-pass RO) มีร้อยละผลตอบแทนของโครงการ (%ROI) และระยะเวลาคืนทุน (Payback period) เท่ากับ ร้อยละ 242, 1.22 ปีและระบบรีไซเคิลแบบสองขั้นตอนร่วมกับระบบการกรองระดับอัลตร้า (UF-RO/RO) เท่ากับร้อยละ 189, 1.97 ปีตามลำดับ แสดงให้เห็นว่าระบบรีไซเคิลแบบสองขั้นตอน (Double-pass RO) มีผลตอบแทนด้านการลงทุน (ROI) ที่ดีที่สุด และระยเวลาการคืนทุนที่เร็วกว่า แม้ว่าระบบรีไซเคิลแบบสองขั้นตอนร่วมกับระบบการกรองระดับอัลตร้า (UF-RO/RO) จะมีคุณภาพน้ำดีกว่า แต่เมื่อพิจารณาต้นทุนแล้ว พบว่าไม่แตกต่างกันมากนัก เนื่องจากระบบรีไซเคิลแบบสองขั้นตอน (Double-pass RO)มีร้อยละผลตอบแทนการลงทุนที่ดีที่สุด และระยะเวลาคืนทุนเร็วกว่า บริษัทฯ จึงเลือกใช้ระบบนี้ในการผลิตน้ำป้อนเข้าสู่หม้อต้มไอน้ำ ส่งผลให้สัดส่วนการใช้น้ำประปาในการอบยางลดลงร้อยละ 26 สัดส่วนการใช้น้ำรีไซเคิลเพิ่มขึ้นถึงร้อยละ 42 และลดการปลดปล่อยก๊าซคาร์บอนไดดอกไซด์ได้ 111.63 ตันคาร์บอนไดออกไซด์ต่อปี

การประเมินคาร์บอนฟุตพริ้นท์องค์กรและการลดก๊าซเรือนกระจกภายใต้โครงการสนับสนุนกิจกรรมลดก๊าซเรือนกระจก: กรณีศึกษาโรงงานผลิตยางคอมพาวด์, ปภาวรินท์ ทรงพัฒนาศิลป์

Chulalongkorn University Theses and Dissertations (Chula ETD)

ปัญหาการเปลี่ยนแปลงสภาพภูมิอากาศในปัจจุบันเกิดจากการเพิ่มขึ้นของปริมาณก๊าซเรือนกระจก ซึ่งมีความรุนแรงและมีแนวโน้มที่จะส่งผลกระทบที่เพิ่มมากขึ้น ประเทศต่าง ๆ และองค์กรทั่วโลกได้กำหนดเป้าหมายในการลดการปล่อยก๊าซเรือนกระจก จึงเป็นสิ่งสำคัญที่ต้องตระหนักถึงและแก้ไขผลกระทบที่เห็นได้ชัดจากการเปลี่ยนแปลงสภาพภูมิอากาศ เพื่อส่งเสริมความร่วมมือในการบรรเทาปัญหาอย่างมีประสิทธิภาพ การศึกษานี้มีวัตถุประสงค์เพื่อประเมินปริมาณคาร์บอนฟุตพริ้นท์องค์กรของโรงงานผลิตยางคอมพาวด์ และประเมินปริมาณการลดการปล่อยก๊าซเรือนกระจกจากกิจกรรมในองค์กร ภายใต้โครงการสนับสนุนกิจกรรมลดก๊าซเรือนกระจก (Low Emission Support Scheme: LESS) ขององค์การบริหารจัดการก๊าซเรือนกระจก (องค์การมหาชน) ในปี พ.ศ. 2565 และ 2566 ผลการศึกษาพบว่าปริมาณการปล่อยก๊าซเรือนกระจกทั้งหมดมีแนวโน้มลดลงจาก 41,675.07 ตันคาร์บอนไดออกไซด์เทียบเท่าต่อปี ในปี พ.ศ. 2565 สู่ 38,043.30 ตันคาร์บอนไดออกไซด์เทียบเท่าต่อปีในปี พ.ศ. 2566 โดยขอบเขตที่ 3 การปล่อยก๊าซเรือนกระจกทางอ้อมอื่นๆ มีสัดส่วนที่สูงที่สุด คิดเป็นร้อยละ 78.55 และ 79.81 ตามลำดับ รองลงมา คือ ขอบเขตที่ 2 การปล่อยจากการใช้พลังงาน มีสัดส่วนคิดเป็นร้อยละ 20.05 และ 18.40 และขอบเขตที่ 1 การปล่อยทางตรงขององค์กร มีสัดส่วนต่ำที่สุด คิดเป็นร้อยละ 1.39 และ 1.80 เมื่อวิเคราะห์ต่อยอดการผลิต พบว่า ปริมาณการปล่อยก๊าซเรือนกระจกประเภทที่ 1 และ 2 ต่อยอดผลิตในปี พ.ศ. 2565 และ 2566 เท่ากับ 0.1717 และ 0.1699 ตามลำดับ ขณะที่ปริมาณการปล่อยก๊าซเรือนกระจกขอบเขตที่ 1 2 และ 3 ต่อยอดผลิต เท่ากับ 0.8005 และ 0.8413 ตันคาร์บอนไดออกไซด์เทียบเท่าต่อตัน ผลการศึกษาในการลดก๊าซเรือนกระจกจากการดำเนินกิจกรรมภายในองค์กรสามารถลดปริมาณการปล่อยก๊าซเรือนกระจกในปี พ.ศ. 2565 และ 2566 เท่ากับ 2,255.29 ตันคาร์บอนไดออกไซด์เทียบเท่า โดยการติดตั้งระบบพลังงานหมุนเวียนจากแสงอาทิตย์ (Solar Rooftop) สามารถลดปริมาณก๊าซเรือนกระจกได้ในปี พ.ศ. 2565 …

Magnetic Spin Transport Coils For The N2edm Experiment, David C. Bowles

Theses and Dissertations--Physics and Astronomy

The n2EDM experiment is being construct at Paul Scherrer Institute to measure the electric dipole moment of the neutron (nEDM), in a search for new physics which could help explain the baryon asymmetry of the universe. To reach the experimental sensitivity goal of $d_n \sim 10^{-27}$, over an order of magnitude improvement from the current world limit, a spin polarization transfer efficiency of 99\% for ultracold neutrons entering or exiting the precession chamber is required, placing a stringent requirement on the adiabaticity of the magnetic field taper in the neutron guide system. The spin transport fields transition from 5~T (longitudinal) …

Qcd Analysis Of Flavor-Nonchanging Hadronic Weak Processes Through Next-To-Leading Order, Girish Lingadahalli Muralidhara

Theses and Dissertations--Physics and Astronomy

Studies in quantum chromodynamics (QCD), the fundamental theory of the strong interactions, of low-energy hadronic weak processes utilize an effective Hamiltonian framework. Below the weak-mass scale, an effective Hamiltonian contains a series of Wilson coefficients and four-quark operators that come from the operator product expansion in the Standard Model. The effective hadronic Hamiltonian pertinent to a weak process is then obtained via a renormalization group analysis in QCD from the weak-mass scale to the low-energy scale of O(2 GeV). In this thesis, the construction and phenomenological implications of such an effective Hamiltonian for flavor-conserving, parity-violating quark processes in the Standard …

Techniques For Optimizing Neutron Beta Decay Particle Detection, Austin W. Nelsen

Theses and Dissertations--Physics and Astronomy

Over the last couple decades, use of free neutron beta decay (n → p + e^- + ν_e) to extract the up-down quark transition element V_ud has become competitive with more conventional Fermi decays. Extraction of V_ud requires measurements of the vector to axial-vector coupling constant ratio λ and the free neutron lifetime τ_n. With a precise determination of V_ud, the 2.8σ departure from CKM unitarity can be addressed.

Nab, located at the Spallation Neutron Source at ORNL, will measure the electron-neutrino momentum correlation coefficient a (which couples quadratically …

Development Of A Source To Detector Simulation Of The Los Alamos National Lab Neutron Electric Dipole Moment Experiment, Dillon Buskirk

Theses and Dissertations--Physics and Astronomy

The Los Alamos National Laboratory (LANL) neutron electric dipole moment (nEDM) experiment is planning an increased precision measurement of the neutron’s permanent electric dipole moment. LANL nEDM expects to lower the statistical uncertainty to δd_LANL = 2 × 10−27 e cm after a year of live-time, which puts a more stringent upper bound on the nEDM. This statistical uncertainty is an order of magnitude less than the current best measurement set by nEDM at PSI. To reach this goal, the LANL nEDM collaboration requires a simulation tool that can tackle optimization problems, investigate systematic effects, and provide mock data …

Development Of A Novel Beam-Type Neutron Lifetime Experiment Using Ultracold Neutrons, Nicholas Floyd

Theses and Dissertations--Physics and Astronomy

Precision measurements of the neutron lifetime are critical to tests of the Standard Model. The CKM quark mixing matrix has recently been shown to deviate from unitarity in the top row, motivating the development of alternative extractions of the first element. Complementary measurements of the neutron’s lifetime and decay correlations can be used to accomplish this.

While the reported neutron lifetime by the Particle Data Group is taken from ultracold neutron (UCN) measurements, a separate class of experiments suggest a value in four sigma disagreement, meriting further study. The goal of the UCNProBe experiment at Los Alamos National Laboratory is …

The Application Of Novel Machine Learning Algorithms To Study Multi-Dimensional Fragmentation Functions Of Hadrons In Jets At Star, Hannah A. Harrison-Smith

Theses and Dissertations--Physics and Astronomy

Hadronization, the process by which colored quarks and gluons shower from high energy collisions and recombine to form stable, experimentally-observable particles, is a fundamental aspect of Quantum Chromodynamics (QCD) that is not yet fully understood. Fragmentation functions, typically measured in electron-positron collisions, encapsulate this hadronization process well for quarks. Studying proton-proton collisions offers direct access to gluon fragmentation that other channels like electron-positron do not. Recent theoretical developments have proposed the study of hadronic showers in groupings called jets, introducing the concept of multi-dimensional jet fragmentation functions. This thesis presents the extraction of collinear and transverse momentum-dependent fragmentation functions for …

Precision Neutrino Interactions In And Beyond The Standard Model, Kaushik Borah

Theses and Dissertations--Physics and Astronomy

This dissertation investigates precision measurements of neutrino interactions within the framework of the Standard Model and explores potential extensions beyond it. Neutrinos, often referred to as ghostly particles due to their weak interactions and elusive nature, have long been a frontier in particle physics. Through detailed theoretical modeling and comparison with experimental data, this work focuses on improving our understanding of neutrino-nucleon cross-sections, nucleon form factors, and generalized neutrino interactions. The study begins with a comprehensive examination of the role of vector and axial-vector form factors in neutrino-nucleon scattering and their impact on the interpretation of neutrino oscillation data from …

Leveraging Redundancy As A Link Between Spreading Dynamics On And Of Networks, Felipe Xavier Costa

Electronic Theses & Dissertations (2024 - present)

A constant quest in network science has been in the development of methods to identify the most relevant components in a dynamical system solely via the interaction structure amongst its subsystems. This information allows the development of control and intervention strategies in biochemical signaling and epidemic spreading. We highlight the relevant components in heterogeneous dynamical system by their patterns of redundancy, which can connect how dynamics affect network topology and which pathways are necessary to spreading phenomena on networks. In order to measure the redundancies in a large class of empirical systems, we develop the backbone of directed networks methodology, …

Informational Principles And Structures In Quantum Theory, Yang Yu

Electronic Theses & Dissertations (2024 - present)

This thesis examines the concept of information within the realm of quantum physics, investigating the nuanced relationship between information and physical laws as applied to quantum systems. With no consensus on a single definition of information in the physical sciences, our exploration is partitioned into two significant studies, each addressing distinct aspects of information in quantum contexts.

In the first study, we concentrate on the information that can be obtained from measurement results on identical quantum systems. The traditional approach of using Shannon entropy is limited due to its applicability primarily to discrete probability distributions. By incorporating a Bayesian update …

Compton Scattering Of Mammographic Soft X-Ray Beams By Alkali And Transition Metal Salt Filters Produce X-Ray Interference Zones That May Have Treatment Potential For Localized Cancer Lesions, Subhendra N. Sarkar, Eric Lobel, Sabina Rakhmatova, Derbie Desir, Somdat Kissoon, Daler Djuraev, Katie Tam

Publications and Research

In breast x-ray imaging scattered radiation adds 50% of harmful radiation dose from anisotropic Compton scattering mechanism. We have been working with double layered inorganic salt materials that can induce Compton scattering to the incident mammographic x ray beams (in 20-30 kVp range) with adequate isotropy (angular control). Typically metal nitrates and alkali halide salt layers are shown here to cause low energy radiation interference zones with high and low photon intensities and local flux heterogeneity in terms of flux covariance. Spatial variation of low energy photon flux creates concentrated and sparse radiation zones that may be used to induce …

Effects Of Electron Beam Irradiation On Crmnv And Crmntiv High Entropy Alloys: Nano-Mechanical, Structural, And Thermodynamic Perspectives, N. A. Sultana, Y. S. Mohammed, S. J. Pendleton, J. Vennekate, G. Ciovati, X. Li, H. Baumgart, A. A. Elmustafa

Mechanical & Aerospace Engineering Faculty Publications

Beam exit windows are crucial components of any particle accelerator as they provide an interface between the beamline vacuum and target material at atmospheric media. For high beam power machines, special materials and designs are required to withstand high radiation and mechanical loads, while minimizing energy loss during transition and maximizing window lifetime. This research investigates the impact of electron beam exposure to bulk CrMnV and CrMnTiV high entropy alloys (HEAs) with the primary goal of identifying suitable candidate materials for the design of robust and durable exit window settings. The selection criteria include intrinsic characteristics, power dissipation, and mechanical …

Updating Nuclear Recoil Models In The Noble Element Simulation Technique For The Lux-Zeplin Experiment, Ryan J. Mcmonigle

Electronic Theses & Dissertations (2024 - present)

There is a substantial amount of evidence that a majority of the mass in the universe is comprised of a non-luminous substance, given the name dark matter. Many candidates have been theorized as the solution to the dark matter mystery, with the Weakly Interacting Massive Particle (WIMP) being a favorable candidate. WIMPs may be detectable via interactions with nucleons, a method known as direct detection. The LUX-ZEPLIN (LZ) experiment is a xenon-based dual-phase Time Projection Chamber (TPC), that specializes in searching for WIMP-nucleon interactions. TPCs are used to reconstruct event information using scintillation and ionization, which are products of interactions …

Light Curve And Hardness Tests For Millilensing In Grb 950830, Grb 090717a, And Grb 200716c, Oindabi Mukherjee, Robert J. Nemiroff

Michigan Tech Publications

Two different temporal sections of a single gamma-ray burst (GRB) must be statistically similar to show an internal gravitational lensing signature. Here, two straightforward gravitational lensing tests are defined and applied: a light curve similarity test and a hardness similarity test. Gravitational millilensing has been claimed to be detected within several individual GRBs that contain two emission episodes separated by a time-delay. However, our analyses indicate that none of those claims satisfy both tests. The hardness similarity test performed on GRB 950830 and GRB 090717A found that the ratio between the second and the first emission episodes in each energy …

In Vivo Measurement Of Nadh Fluorescence Lifetime In Skeletal Muscle Via Fiber-Coupled Time-Correlated Single Photon Counting, Kathryn M. Priest, Jacob V. Schluns, Nathania Nischal, Colton L. Gattis, Jeffery C. Wolchok, Timothy J. Muldoon

Biomedical Engineering Faculty Publications and Presentations

Nicotinamide adenine dinucleotide (NADH) is a cofactor that serves to shuttle electrons during metabolic processes such as glycolysis, the tricarboxylic acid cycle, and oxidative phosphorylation (OXPHOS). NADH is autofluorescent, and its fluorescence lifetime can be used to infer metabolic dynamics in living cells. Fiber-coupled time-correlated single photon counting (TCSPC) equipped with an implantable needle probe can be used to measure NADH lifetime in vivo, enabling investigation of changing metabolic demand during muscle contraction or tissue regeneration. This study illustrates a proof of concept for point-based, minimally-invasive NADH fluorescence lifetime measurement in vivo. Volumetric muscle loss (VML) injuries were …

Disaggregating Longer-Term Trends From Seasonal Variations In Measured Pv System Performance, Chibuisi Chinasaokwu Okorieimoh, Brian Norton, Michael Conlon

Articles

Photovoltaic (PV) systems are widely adopted for renewable energy generation, but their performance is influenced by complex interactions between longer-term trends and seasonal variations. This study aims to remove these factors and provide valuable insights for optimising PV system operation. We employ comprehensive datasets of measured PV system performance over five years, focusing on identifying the distinct contributions of longer-term trends and seasonal effects. To achieve this, we develop a novel analytical framework that combines time series and statistical analytical techniques. By applying this framework to the extensive performance data, we successfully break down the overall PV system output into …

Counting Linearly Polarized Gluons With Lattice Qcd, Shuai Zhao

Physics Faculty Publications

We outline an approach to calculate the transverse-momentum-dependent distribution of linearly polarized gluons inside an unpolarized hadron on the lattice with the help of large momentum effective theory. To achieve this purpose, we propose calculating a Euclidean version of the degree of polarization for a fast-moving hadron on the lattice, which is ultraviolet finite, and no soft function subtraction is needed. It indicates a practical way to explore the distribution of the linearly polarized gluons in a proton and the linearly polarized gluon effects in hadron collisions on the lattice.

Accelerating Markov Chain Monte Carlo Sampling With Diffusion Models, N. T. Hunt-Smith, W. Melnitchouk, F. Ringer, N. Sato, A. W. Thomas, M. J. White

Physics Faculty Publications

Global fits of physics models require efficient methods for exploring high-dimensional and/or multimodal posterior functions. We introduce a novel method for accelerating Markov Chain Monte Carlo (MCMC) sampling by pairing a Metropolis-Hastings algorithm with a diffusion model that can draw global samples with the aim of approximating the posterior. We briefly review diffusion models in the context of image synthesis before providing a streamlined diffusion model tailored towards low-dimensional data arrays. We then present our adapted Metropolis-Hastings algorithm which combines local proposals with global proposals taken from a diffusion model that is regularly trained on the samples produced during the …

Magneto-Thermal Limitations In Superconducting Cavities At High Radio-Frequency Fields, I. Parajuli, G. Ciovati, A. Gurevich

Physics Faculty Publications

The performance of superconducting radio-frequency Nb cavities at high radio-frequency (rf) fields in the absence of field emission can be limited by either a sharp decrease of the quality factor Q₀(B_p) above peak surface magnetic fields B_p ∼100 mT or by a quench. We have measured Q₀(B_p) at 2 K of several 1.3 GHz single-cell Nb cavities with different grain sizes, and with different ambient magnetic fields and cooldown rates below the critical temperature. Temperature mapping and a novel magnetic field mapping systems were used to find the location of “hot-spots” …

A Compton Transmission Polarimeter For Dc And Srf Electron Photo-Injectors, G. Blume, M. Bruker, C. Cuevas, H. Dong, Benjamin Fernandes Neres, P. Ghoshal, S. Gopinath, J. Grames, S. Gregory, G. Hays, C. Le Galliard, Sylvain Marsillac, B. Moffit, Thi Nguyen Trung, M. Poelker, R. Suleiman, E. Voutier, S. Zhang

Physics Faculty Publications

A polarimeter was constructed to measure the longitudinal polarization of a spin-polarized electron beam at 5 and 7 MeV. The polarimeter takes advantage of Compton scattering between circularly polarized bremsstrahlung photons produced by a longitudinally polarized electron beam striking a copper radiator and the spin-polarized electrons orbiting the iron atoms of an analyzing magnet. This so-called Compton transmission polarimeter is compact and relatively inexpensive compared to Mott-scattering polarimeters because no spin manipulator is required. This work presents the design of the radiator, analyzing magnet, photon detector assembly, and data acquisition system of the Compton transmission polarimeter as well as beam …

Gluon Helicity From Global Analysis Of Experimental Data And Lattice Qcd Ioffe Time Distributions, J. Karpie, R. M. Whitehill, W. Melnitchouk, C. Monahan, K. Orginos, J.-W. Qui, D. G. Richards, N. Sato, S. Zafeiropoulos, Jefferson Lab Angular Momentum And Hadstruc Collaboration

Physics Faculty Publications

We perform a new global analysis of spin-dependent parton distribution functions with the inclusion of Ioffe time pseudodistributions computed in lattice QCD (LQCD), which are directly sensitive to the gluon helicity distribution, Δg. These lattice data have an analogous relationship to parton distributions as do experimental cross sections, and can be readily included in global analyses. We focus in particular on the constraining capability of current LQCD data on the sign of Δg at intermediate parton momentum fractions x, which was recently brought into question by analysis of data in the absence of parton positivity constraints. …

Evolution Of Efimov States, Sebastian M. Dawid, Md Habib E. Islam, Raúl A. Briceño, Andrew W. Jackura

Physics Faculty Publications

The Efimov phenomenon manifests itself as an emergent discrete scaling symmetry in the quantum three-body problem. In the unitarity limit, it leads to an infinite tower of three-body bound states with energies forming a geometric sequence. In this work, we study the evolution of these so-called Efimov states using relativistic scattering theory. We identify them as poles of the three-particle 𝑆 matrix in the complex energy plane, and we study how they transform from virtual states through bound states to resonances when we change the interaction strength. We dial the scattering parameters toward the unitarity limit and observe the emergence …