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Articles 331 - 360 of 20594

Full-Text Articles in Physics

Constraining The Sources Of Ultra-High-Energy Cosmic Rays Across And Above The Ankle With The Spectrum And Composition Data Measured At The Pierre Auger Observatory, A. Abdul Halim, P. Abreu, M. Aglietta, I. Allekotte, K. Almeida Cheminant, A. Almela, B. Fick, D. Nitz, I. Norwood, A. Puyleart, Et. Al May 2023

Constraining The Sources Of Ultra-High-Energy Cosmic Rays Across And Above The Ankle With The Spectrum And Composition Data Measured At The Pierre Auger Observatory, A. Abdul Halim, P. Abreu, M. Aglietta, I. Allekotte, K. Almeida Cheminant, A. Almela, B. Fick, D. Nitz, I. Norwood, A. Puyleart, Et. Al

Michigan Tech Publications

In this work we present the interpretation of the energy spectrum and mass composition data as measured by the Pierre Auger Collaboration above 6 × 1017 eV. We use an astrophysical model with two extragalactic source populations to model the hardening of the cosmic-ray flux at around 5 × 1018 eV (the so-called "ankle"feature) as a transition between these two components. We find our data to be well reproduced if sources above the ankle emit a mixed composition with a hard spectrum and a low rigidity cutoff. The component below the ankle is required to have a very soft spectrum …


Effect On Focusing Fields By Ferromagnetic Cell Cores In Linear Induction Accelerators, Cooper Guillaume May 2023

Effect On Focusing Fields By Ferromagnetic Cell Cores In Linear Induction Accelerators, Cooper Guillaume

Senior Honors Theses

In the Los Alamos National Laboratories DARHT facility, there are two perpendicular linear induction accelerators, LIAs. The LIAs’ solenoids produce magnetic fields which focus the electron beam. Simultaneously, the accelerating pulse creates a magnetic field. These two field intensities act upon a ferromagnetic material in the cells to enhance magnetic flux density. Due to the nonlinearity of the material, this flux density will reach a saturation point. In turn, the magnetic field intensity of the axial solenoidal magnetic field will be affected and slightly altered. The width of the electron beam will increase, causing a decrease in effectiveness. Through simulation, …


Assessment Of Bridge Pier Response To Fire, Vehicle Impact, And Air Blast, Chen Fang, Qusai Alomari, Daniel G. Linzell May 2023

Assessment Of Bridge Pier Response To Fire, Vehicle Impact, And Air Blast, Chen Fang, Qusai Alomari, Daniel G. Linzell

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Highway bridges exposed to intentional or unintentional fire followed by combined vehicle impact and air blast are at risk of significant damage and, possibly, collapse. Limited studies examining the complex effects of these extreme demands on bridge support elements and parametrizing their response and damage are found in the open literature. Research that is presented is part of an ongoing numerical investigation examining round, multi-column, reinforced concrete (RC), bridge pier behavior subject to multi-hazard scenarios involving fire, vehicle impact, and air blast. Detailed nonlinear finite element analysis models of single columns and multi-column piers supported by a pile foundation system …


Quantum Phases Of Lattice Dipolar Bosons Coupled To A High-Finesse Cavity, Yaghmorassene Hebib, Chao Zhang, Jin Yang, Barbara Capogrosso-Sansone May 2023

Quantum Phases Of Lattice Dipolar Bosons Coupled To A High-Finesse Cavity, Yaghmorassene Hebib, Chao Zhang, Jin Yang, Barbara Capogrosso-Sansone

Physics

Two types of long-range interactions, dipolar interaction and cavity-mediated interaction, lead to exotic quantum phases. Both interactions were realized and observed in optical lattice setups. Here, we study quantum phases of dipolar bosons trapped in optical lattices and coupled to a high-finesse cavity where both dipolar interaction and cavity-mediated interaction coexist. We perform quantum Monte Carlo simulations and find that the checkerboard solid is enhanced and the checkerboard supersolid phase can exist in a wide range of densities (e.g., 0.27≲n≲0.73). Our unbiased numerical results suggest that both solid and supersolid phases can be achieved experimentally with magnetic atoms coupled to …


Cloud Microphysical Response To Entrainment And Mixing Is Locally Inhomogeneous And Globally Homogeneous: Evidence From The Lab, Jaemin Yeom, Ian Helman, Prasanth Prabhakaran, Jesse Anderson, Fan Yang, Raymond Shaw, Will Cantrell Apr 2023

Cloud Microphysical Response To Entrainment And Mixing Is Locally Inhomogeneous And Globally Homogeneous: Evidence From The Lab, Jaemin Yeom, Ian Helman, Prasanth Prabhakaran, Jesse Anderson, Fan Yang, Raymond Shaw, Will Cantrell

Michigan Tech Research Data

The effects of entrainment-mixing on the cloud droplet size distribution are examined in the Pi cloud chamber that creates a turbulent supersaturated environment for cloud formation. The experiments are conducted with a temperature-controlled flange to mimic the entrainment-mixing process. The entrainment zone is created at the center of the top surface of the chamber, allowing dry air of controlled temperature (Te) and flow rate (Qe) to flow into the mixing cloud region. Due to the large-scale circulation, the downwind region is directly affected by entrained dry air from the flange, whereas the upwind region is representative …


The Influence Of The Substrate On The Functionality Of Spin Crossover Molecular Materials, Saeed Yazdani, Jared Phillips, Thilini K. Ekanayaka, Ruihua Cheng, Peter A. Dowben Apr 2023

The Influence Of The Substrate On The Functionality Of Spin Crossover Molecular Materials, Saeed Yazdani, Jared Phillips, Thilini K. Ekanayaka, Ruihua Cheng, Peter A. Dowben

Department of Physics and Astronomy: Faculty Publications

Spin crossover complexes are a route toward designing molecular devices with a facile readout due to the change in conductance that accompanies the change in spin state. Because substrate effects are important for any molecular device, there are increased efforts to characterize the influence of the substrate on the spin state transition. Several classes of spin crossover molecules deposited on different types of surface, including metallic and non-metallic substrates, are comprehensively reviewed here. While some non-metallic substrates like graphite seem to be promising from experimental measurements, theoretical and experimental studies indicate that 2D semiconductor surfaces will have minimum interaction with …


Optical Fiber Tip Micro Anemometer, Jeremiah C. Williams, Hengky Chandrahalim Apr 2023

Optical Fiber Tip Micro Anemometer, Jeremiah C. Williams, Hengky Chandrahalim

AFIT Patents

A passive microscopic flow sensor includes a three-dimensional microscopic optical structure formed on a cleaved tip of an optical fiber. The three-dimensional microscopic optical structure includes a post attached off-center to and extending longitudinally from the cleaved tip of the optical fiber. A rotor of the three-dimensional microscopic optical structure is received for rotation on the post. The rotor has more than one blade. Each blade has a reflective undersurface that reflects a light signal back through the optical fiber when center aligned with the optical fiber, the blades of the rotor shaped to rotate at a rate related to …


Stabilizing Polar Phases In Binary Metal Oxides By Hole Doping, Tengfei Cao, Guodong Ren, Ding-Fu Shao, Evgeny Y. Tsymbal, Rohan Mishra Apr 2023

Stabilizing Polar Phases In Binary Metal Oxides By Hole Doping, Tengfei Cao, Guodong Ren, Ding-Fu Shao, Evgeny Y. Tsymbal, Rohan Mishra

Department of Physics and Astronomy: Faculty Publications

The recent observation of ferroelectricity in the metastable phases of binary metal oxides, such as HfO2, ZrO2, Hf0.5Zr0.5O2, and Ga2O3, has garnered a lot of attention. These metastable ferroelectric phases are typically stabilized using epitaxial strain, alloying, or defect engineering. Here, we propose that hole doping plays a key role in the stabilization of polar phases in binary metal oxides. Using first-principles density-functional-theory calculations, we show that holes in these oxides mainly occupy one of the two oxygen sublattices. This hole localization, which is more pronounced …


Uncertainty From The Aharonov–Vaidman Identity, Matthew S. Leifer Apr 2023

Uncertainty From The Aharonov–Vaidman Identity, Matthew S. Leifer

Mathematics, Physics, and Computer Science Faculty Articles and Research

In this article, I show how the Aharonov–Vaidman identity A|ψ>=<A⟩|ψ>+ΔA| ψA> can be used to prove relations between the standard deviations of observables in quantum mechanics. In particular, I review how it leads to a more direct and less abstract proof of the Robertson uncertainty relation ΔAΔB≥12|< [A,B]>| than the textbook proof. I discuss the relationship between these two proofs and show how the Cauchy–Schwarz inequality can be derived from the Aharonov–Vaidman identity. I give Aharonov–Vaidman based proofs of the Maccone–Pati uncertainty relations …


The Kp Index And Behavior Of Quiet Periods, Collette Walbeck Apr 2023

The Kp Index And Behavior Of Quiet Periods, Collette Walbeck

Physics Capstone Projects

The Kp-index quantifies the electromagnetic effects in the Earth’s atmosphere and is used in a variety of scientific fields. Higher Kp values tend to be the focus in these fields as they relate to high solar activity and geomagnetic storms. This study aimed to examine the significance, if any, of lower Kp indices. A simple data analysis was performed on continuous sequences of low Kp values, deemed Quiet Periods. Both the daily average of the values and the full set of Kp data were used. A decaying exponential relationship was discovered between the length of these periods and their frequencies …


High Frequency Radio Communication, Tyler Larsen Apr 2023

High Frequency Radio Communication, Tyler Larsen

Physics Capstone Projects

High frequency radio communication has been the most reliable form of communication for many decades. Over that period, we have learned and experienced times of enhanced signals along with complete radio blackouts. The purpose of this research is to collect and analyze radio signal data to see the evidence of various reasons as to why these phenomena occur. A radio antenna was set up at USU campus to retrieve the signals from beacon networks across the globe that transmit signals every 15 minutes. By tracking a few of these signals we can locate the times of discrepancies in the signals …


Is There Causation In Fundamental Physics? New Insights From Process Matrices And Quantum Causal Modelling, Emily Adlam Apr 2023

Is There Causation In Fundamental Physics? New Insights From Process Matrices And Quantum Causal Modelling, Emily Adlam

Mathematics, Physics, and Computer Science Faculty Articles and Research

In this article we set out to understand the significance of the process matrix formalism and the quantum causal modelling programme for ongoing disputes about the role of causation in fundamental physics. We argue that the process matrix programme has correctly identified a notion of ‘causal order’ which plays an important role in fundamental physics, but this notion is weaker than the common-sense conception of causation because it does not involve asymmetry. We argue that causal order plays an important role in grounding more familiar causal phenomena. Then we apply these conclusions to the causal modelling programme within quantum foundations, …


Effectiveness Of Multilayer Graded-Z Forms Of Radiation Shielding, Brinley Packer Apr 2023

Effectiveness Of Multilayer Graded-Z Forms Of Radiation Shielding, Brinley Packer

Physics Capstone Projects

This study explored how different forms of radiation shielding were more or less effective than standard single-layer shielding. Beta and gamma radiation sources were used and measured using a Geiger counter to determine how well the various forms of shielding protect against the radiation. The shielding effectiveness of standard homogeneous materials (e.g., graphite, carbon/epoxy composites, aluminum, and lead) of various thicknesses for different radiation sources was measured to provide standards for comparison. Once a basis of effective shielding was established, the study can go into greater depth into how to use shielding materials to be more effective, to better shield …


Applying Bioactive Glass Beads For Long-Term Drug Delivery, Marie O. Sykes, Rashi Sharma Apr 2023

Applying Bioactive Glass Beads For Long-Term Drug Delivery, Marie O. Sykes, Rashi Sharma

Physics and Astronomy Presentations

Bioactive glass beads have been used to distribute medicine over extended periods of time in limited uses. They can be engineered to have a porous and hollow structure, and using Mo-Sci's OL-GL 1756b (1756b), the fundamental notion of dosage distribution can be tested in preparation to design the optimal glass for medicine distribution. A few key factors in this is how long does it take the liquid to release from the beads, how do the beads decay, and how well the glass can bond to human tissue. This research demonstrates the capacities of the 1756b type as a promising start …


Volume 14, Ireland Seagle, Dalton C. Whitby, Cassandra Poole, Rachel Cannon, Heidi Parker-Combes, Devon G. Shifflett, Antonio Harvey Apr 2023

Volume 14, Ireland Seagle, Dalton C. Whitby, Cassandra Poole, Rachel Cannon, Heidi Parker-Combes, Devon G. Shifflett, Antonio Harvey

Incite: The Journal of Undergraduate Scholarship

Table of Contents:

  • Introduction: Dr. Amorette Barber
  • From the Editor: Dr. Larissa "Kat" Tracy
  • From the Designers: Rachel English, Rachel Hanson
  • Hungry Like the Wolf: The Wolf as Metaphor in Paramount Network’s Yellowstone: Ireland Seagle
  • “Floating Cities”: Illustrating the Commercial and Conservation Conflict of Alaskan Cruise Ship Tourism: Dalton C. Whitby
  • What Can You Do When Your Genes are the Enemy? Current Applications of Gene Manipulation and the Associated Ethical Considerations: Cassandra Poole
  • La doble cara: un tema romántico en las obras de Larra y Hawthorne: Rachel Cannon
  • Resolving a Conflict: How to …


Tailoring The Polyurethane Foam/Rgo/Batio3 Pressure Sensor For Human Activities, Mohamed Morsy Apr 2023

Tailoring The Polyurethane Foam/Rgo/Batio3 Pressure Sensor For Human Activities, Mohamed Morsy

Nanotechnology Research Centre

No abstract provided.


For The Dissertation: A Classification Of Tensors In Ecsk Theory, Joshua James Leiter, Charles G. Torre Apr 2023

For The Dissertation: A Classification Of Tensors In Ecsk Theory, Joshua James Leiter, Charles G. Torre

Physics Student Research

This dissertation presents a Petrov/Plebanski/Segre/Algebraic (PPSA) classification scheme for both the curvature and torsion tensors in Einstein-Cartan-Sciama-Kibble theory (ECSK); additionally the work includes a software package in Maple with computational and PPSA classification tools. Six different solutions are classified using the new software tools developed. We also present a new boundary term for ECSK-NMC scalar theory to ensure Dirichlet boundary conditions. New work completed includes the decomposition of an arbitrary 4th rank tensor under SO (p, q), equivalent SL (2, C) irreducible spinor decompositions of arbitrary 3rd and 4th rank tensors. We provide new proofs that the corresponding spinors are …


Dynamical Formation Of Two-Fold Fragmented Many-Body State Induced By An Impurity In A Double-Well, Jie Chen, Simeon I. Mistakidis, Peter Schmelcher Apr 2023

Dynamical Formation Of Two-Fold Fragmented Many-Body State Induced By An Impurity In A Double-Well, Jie Chen, Simeon I. Mistakidis, Peter Schmelcher

Physics Faculty Research & Creative Works

We Unravel The Correlated Quantum Quench Dynamics Of A Single Impurity Immersed In A Bosonic Environment Confined In An One-Dimensional Double-Well Potential. A Particular Emphasis Is Placed On The Structure Of The Time-Evolved Many-Body (MB) Wave Function By Relying On A Schmidt Decomposition Whose Coefficients Directly Quantify The Number Of Configurations That Are Macroscopically Populated. For A Non-Interacting Bosonic Bath And Weak Postquench Impurity-Bath Interactions, We Observe The Dynamical Formation Of A Two-Fold Fragmented MB State Which Is Related To Intra-Band Excitation Processes Of The Impurity And Manifests As A Two-Body Phase Separation (Clustering) Between The Two Species For Repulsive …


Calibrating The Faraday Cup For Ion Beams Using Rutherford Backscattering Spectroscopy, Joseph Fogt, Nolan Miles, Megan Haeussler, Hope Weeda Apr 2023

Calibrating The Faraday Cup For Ion Beams Using Rutherford Backscattering Spectroscopy, Joseph Fogt, Nolan Miles, Megan Haeussler, Hope Weeda

22nd Annual Celebration of Undergraduate Research and Creative Activity (2023)

Particle accelerators are useful pieces of technology for a variety of experiments, from testing for contaminants in the water supply to testing the durability of materials exposed to radiation. In order to measure the amount of radiation being delivered by the accelerator’s beam, a Faraday cup is used. This tool can measure the amount of ions impacting a surface by measuring the current generated by the incident ions; however, they often overestimate current due to the emission of secondary electrons. This is an inherent property of the Faraday cup, but we still want an accurate measurement of the beam current. …


Effects Of Autoionizing Resonances On Wave-Packet Dynamics Studied By Time-Resolved Photoelectron Spectroscopy, Pengju Zhang, Van Hung Hoang, Chuncheng Wang, Tran Trung Luu, Vít Svoboda, Anh-Thu Le, Hans Jakob Wörner Apr 2023

Effects Of Autoionizing Resonances On Wave-Packet Dynamics Studied By Time-Resolved Photoelectron Spectroscopy, Pengju Zhang, Van Hung Hoang, Chuncheng Wang, Tran Trung Luu, Vít Svoboda, Anh-Thu Le, Hans Jakob Wörner

Physics Faculty Research & Creative Works

We Report a Combined Experimental and Theoretical Study on the Effect of Autoionizing Resonances in Time-Resolved Photoelectron Spectroscopy. the Coherent Excitation of N2 by ∼14.15 EV Extreme-Ultraviolet Photons Prepares a Superposition of Three Dominant Adjacent Vibrational Levels (V′=14-16) in the Valence B′ ςu+1 State, Which Are Probed by the Absorption of Two or Three Near-Infrared Photons (800 Nm). the Superposition Manifests itself as Coherent Oscillations in the Measured Photoelectron Spectra. a Quantum-Mechanical Simulation Confirms that Two Autoionizing Rydberg States Converging to the Excited a Π2u and B ςu+2 N2+ Cores Are Accessed by the Resonant Absorption of …


Non-Hermitian Edge Burst Without Skin Localization, Cem Yuce, Hamidreza Ramezani Apr 2023

Non-Hermitian Edge Burst Without Skin Localization, Cem Yuce, Hamidreza Ramezani

Physics and Astronomy Faculty Publications and Presentations

In a class of non-Hermitian quantum walk in lossy lattices with open boundary conditions, an unexpected peak in the distribution of the decay probabilities appears at the edge, referred to as an edge burst. It is proposed that the edge burst originates jointly from the non-Hermitian skin effect (NHSE) and the imaginary gaplessness of the spectrum [W.-T. Xue et al., Phys. Rev. Lett. 128, 120401 (2022)]. Using a particular one-dimensional lossy lattice with a nonuniform loss rate, we show that the edge burst can occur even in the absence of skin localizations. Furthermore, we discuss that the edge …


The Spin Polarization Of Palladium On Magneto-Electric Cr2O3, Takashi Komesu, Will Echtenkamp,, Christian H. Binek, Peter A. Dowben Apr 2023

The Spin Polarization Of Palladium On Magneto-Electric Cr2O3, Takashi Komesu, Will Echtenkamp,, Christian H. Binek, Peter A. Dowben

Department of Physics and Astronomy: Faculty Publications

While induced spin polarization of a palladium (Pd) overlayer on antiferromagnetic and magneto-electric Cr2O3(0001) is possible because of the boundary polarization at the Cr2O3(0001), in the single domain state, the Pd thin film appears to be ferromagnetic on its own, likely as a result of strain. In the conduction band, we find the experimental evidence of ferromagnetic spin polarized in Pd thin films on a Cr2O3(0001) single crystal, especially in the thin limit, Pd thickness of around 1–4 nm. Indeed there is significant spin polarization in 10 Å …


E6 Models In Light Of Precision MW Measurements, Vernon Barger, Cash Hauptmann, Peisi Huang, Wai-Yee Keung Apr 2023

E6 Models In Light Of Precision MW Measurements, Vernon Barger, Cash Hauptmann, Peisi Huang, Wai-Yee Keung

Department of Physics and Astronomy: Faculty Publications

We propose a solution to the recent W mass measurement by embedding the Standard Model within E6 models. The presence of a new U(1) group shifts the W boson mass at the tree level and introduces a new gauge boson Z' which has been searched for at collider experiments. In this article, we identify the parameter space that explains the new W mass measurement and is consistent with current experimental Z' searches. As U(1) extensions can be accommodated in supersymmetric models, we also consider the supersymmetric scenario of E6 models, and show that a 125 GeV …


The Camels Project: Public Data Release, Francisco Villaescusa-Navarro, Shy Genel, Daniel Anglés-Alcázar, Lucia A. Perez, Pablo Villanueva-Domingo, Digvijay Wadekar, Helen Shao, Faizan G. Mohammad, Sultan Hassan, Emily Moser, Erwin T. Lau, Luis Fernando Machado Poletti Valle, Andrina Nicola, Leander Thiele, Yongseok Jo, Oliver H.E. Philcox, Benjamin D. Oppenheimer, Megan Tillman, Chang Hoon Hahn, Neerav Kaushal, Et Al. Apr 2023

The Camels Project: Public Data Release, Francisco Villaescusa-Navarro, Shy Genel, Daniel Anglés-Alcázar, Lucia A. Perez, Pablo Villanueva-Domingo, Digvijay Wadekar, Helen Shao, Faizan G. Mohammad, Sultan Hassan, Emily Moser, Erwin T. Lau, Luis Fernando Machado Poletti Valle, Andrina Nicola, Leander Thiele, Yongseok Jo, Oliver H.E. Philcox, Benjamin D. Oppenheimer, Megan Tillman, Chang Hoon Hahn, Neerav Kaushal, Et Al.

Michigan Tech Publications

The Cosmology and Astrophysics with Machine Learning Simulations (CAMELS) project was developed to combine cosmology with astrophysics through thousands of cosmological hydrodynamic simulations and machine learning. CAMELS contains 4233 cosmological simulations, 2049 N-body simulations, and 2184 state-of-the-art hydrodynamic simulations that sample a vast volume in parameter space. In this paper, we present the CAMELS public data release, describing the characteristics of the CAMELS simulations and a variety of data products generated from them, including halo, subhalo, galaxy, and void catalogs, power spectra, bispectra, Lyα spectra, probability distribution functions, halo radial profiles, and X-rays photon lists. We also release over 1000 …


Wallaby Pre-Pilot Survey: Radio Continuum Properties Of The Eridanus Supergroup, J. A. Grundy, O. I. Wong, K. Lee-Waddell, N. Seymour, B. -Q. For, C. Murugeshan, B. S. Koribalski, Juan P. Madrid, J. Rhee, T. Westmeier Apr 2023

Wallaby Pre-Pilot Survey: Radio Continuum Properties Of The Eridanus Supergroup, J. A. Grundy, O. I. Wong, K. Lee-Waddell, N. Seymour, B. -Q. For, C. Murugeshan, B. S. Koribalski, Juan P. Madrid, J. Rhee, T. Westmeier

Physics and Astronomy Faculty Publications and Presentations

We present the highest resolution and sensitivity ∼ 1.4 GHz continuum observations of the Eridanus supergroup obtained as a part of the Widefield Australian Square Kilometer Array Pathfinder (ASKAP) L-band Legacy All-sky Blind surveY (WALLABY) pre-pilot observations using the ASKAP. We detect 9461 sources at 1.37 GHz down to a flux density limit of ∼ 0.1 mJy at 6.1′′×7.9′′ resolution with a median root mean square of 0.05 mJy beam −1 . We find that the flux scale is accurate to within 5 % (compared to NVSS at 1.4 GHz). We then determine the global properties of eight Eridanus supergroup …


Test Beam Performance Of A Cbc3-Based Mini-Module For The Phase-2 Cms Outer Tracker Before And After Neutron Irradiation, Cms Collaboration Apr 2023

Test Beam Performance Of A Cbc3-Based Mini-Module For The Phase-2 Cms Outer Tracker Before And After Neutron Irradiation, Cms Collaboration

Department of Physics and Astronomy: Faculty Publications

The Large Hadron Collider (LHC) at CERN will undergo major upgrades to increase the instantaneous luminosity up to 5–7.5 × 1034 cm-2s-1. This High Luminosity upgrade of the LHC (HL-LHC) will deliver a total of 3000–4000 fb-1 of proton-proton collisions at a center-of-mass energy of 13–14 TeV. To cope with these challenging environmental conditions, the strip tracker of the CMS experiment will be upgraded using modules with two closely-spaced silicon sensors to provide information to include tracking in the Level-1 trigger selection. This paper describes the performance, in a test beam experiment, of the …


Mesopause Region Temperature And Na Number Density Between 1990 And 2017, Tao Yuan, Chiao-Yao She Apr 2023

Mesopause Region Temperature And Na Number Density Between 1990 And 2017, Tao Yuan, Chiao-Yao She

Browse all Datasets

The Colorado State University (CSU) Na lidar performed nocturnal mesopause region Na density and temperature observations between March 1990 and March 2010 at Fort Collins, CO (41.6N, 105W). The lidar was relocated to Utah State University (USU) campus and has continued its regular observation at Logan, Utah (42N, 112W) since September 2010.


A Method To Measure Positron Beam Polarization Using Optically Polarized Atoms, Joshua Joshua Machacek, Sean Hodgman, Stephen Buckman, T. J. Gay Apr 2023

A Method To Measure Positron Beam Polarization Using Optically Polarized Atoms, Joshua Joshua Machacek, Sean Hodgman, Stephen Buckman, T. J. Gay

Department of Physics and Astronomy: Faculty Publications

We outline an experimental technique for measuring the degree of polarization of a positron beam using an optically pumped, spin-polarized Rb target. The technique is based on the production and measurement of the ortho- and para-positronium fractions through positron collisions with the Rb atoms as a function of their polarization. Using realistic estimates for the cross sections and experimental parameters involved, we estimate that a polarization measurement with an uncertainty of 3% of the measured value can be achieved in an hour


The Temporal Asymmetry Of Influence Is Not Statistical, Emily Adlam Apr 2023

The Temporal Asymmetry Of Influence Is Not Statistical, Emily Adlam

Mathematics, Physics, and Computer Science Faculty Articles and Research

We argue that the temporal asymmetry of influence is not merely the result of thermodynamics: it is a consequence of the fact that modal structure of the universe must admit only processes which cannot give rise to contradictions. We appeal to the process matrix formalism developed in the field of quantum foundations to characterise processes which are compatible with local free will whilst ruling out contradictions, and argue that this gives rise to ‘consistent chaining’ requirements that explain the temporal asymmetry of influence. We compare this view to the perspectival account of causation advocated by Price and Ramsey.


Applying Hallgren’S Algorithm For Solving Pell’S Equation To Finding The Irrational Slope Of The Launch Of A Billiard Ball, Sangheon Choi Apr 2023

Applying Hallgren’S Algorithm For Solving Pell’S Equation To Finding The Irrational Slope Of The Launch Of A Billiard Ball, Sangheon Choi

Mathematical Sciences Technical Reports (MSTR)

This thesis is an exploration of Quantum Computing applied to Pell’s equation in an attempt to find solutions to the Billiard Ball Problem. Pell’s equation is a Diophantine equation in the form of x2 − ny2 = 1, where n is a given positive nonsquare integer, and integer solutions are sought for x and y. We will be applying Hallgren’s algorithm for finding irrational periods in functions, in the context of billiard balls and their movement on a friction-less unit square billiard table. Our central research question has been the following: Given the cutting sequence of the billiard …