Physics Commons^™

Similar Ultrafast Dynamics Of Several Dissimilar Dirac And Weyl Semimetals, Christopher P. Weber, Bryan S. Berggren, Madison G. Masten, Thomas C. Ogloza, Skylar Deckoff-Jones, Julien Madéo, Michael K. L. Man, Keshav M. Dani, Lingxiao Zhao, Genfu Chen, Jinyu Liu, Zhiqiang Mao, Leslie M. Schoop, Bettina V. Lotsch, Stuart S. P. Parkin, Mazhar Ali

Physics

Recent years have seen the rapid discovery of solids whose low-energy electrons have a massless, linear dispersion, such as Weyl, line-node, and Dirac semimetals. The remarkable optical properties predicted in these materials show their versatile potential for optoelectronic uses. However, little is known of their response in the picoseconds after absorbing a photon. Here, we measure the ultrafast dynamics of four materials that share non-trivial band structure topology but that differ chemically, structurally, and in their low-energy band structures: ZrSiS, which hosts a Dirac line node and Dirac points; TaAs and NbP, which are Weyl semimetals; and Sr_{1–y …}

L-Edge Spectroscopy Of Dilute, Radiation-Sensitive Systems Using A Transition-Edge-Sensor Array, Charles J. Titus, Michael L. Baker, Sang Jun Lee, Hsiao-Mei Cho, William B. Doriese, Joseph W. Fowler, Kelly Gaffney, Johnathon D. Gard, Gene C. Hilton, Chris Kenney, Jason Knight, Dale Li, Ronald Marks, Michael P. Minitti, Kelsey M. Morgan, Galen C. O'Neil, Carl D. Reintsema, Daniel R. Schmidt, Dimosthenis Sokaras, Daniel S. Swetz, Joel N. Ullom, Tsu-Chien Weng, Christopher Williams, Betty A. Young, Kent D. Irwin, Edward I. Solomon, Dennis Nordlund

Physics

We present X-ray absorption spectroscopy and resonant inelastic X-ray scattering (RIXS) measurements on the iron L-edge of 0.5 mM aqueous ferricyanide. These measurements demonstrate the ability of high-throughput transition-edge-sensor (TES) spectrometers to access the rich soft X-ray (100–2000 eV) spectroscopy regime for dilute and radiation-sensitive samples. Our low-concentration data are in agreement with high-concentration measurements recorded by grating spectrometers. These results show that soft-X-ray RIXS spectroscopy acquired by high-throughput TES spectrometers can be used to study the local electronic structure of dilute metal-centered complexes relevant to biology, chemistry, and catalysis. In particular, TES spectrometers have a unique ability to characterize …

Investigation Of Neutron Induced Ternary Fission With The Niffte Time Projection Chamber, Alex C. Kemnitz

Physics

Ternary fission is a rare occurrence in which three particles are produced from a single fission event. This analysis uses tracked fission event data recorded by NIFFTE’s time projection chamber with a series of refined cuts to isolate all possible ternary events. The experiment used two targets, each consisting of two isotopes; one target was Pu-239 and U-235, and the other was U-238 and U-235. The data was used to measure the ternary/binary fission ratios for each isotope. The ratios for the Pu-239 and U-235 target that were found are shown to be too high due to alpha contamination. The …

Faraday-Talbot Effect From A Circular Array Of Pillars, Jessica J. Pilgram

Physics

When an oil bath is vertically oscillating with an acceleration above some critical value, known as the Faraday threshold, the bath surface becomes unstable and nonlinear standing wave patterns emerge. One phenomenon that has been observed above the Faraday threshold is the formation of Faraday-Talbot carpets, resulting from near-field diffraction. The optical Talbot effect occurs when a monochromatic wave passes through a diffraction grating. In the near-field, the formation of self- images is observed at integer multiples of what is known as the Talbot length. These two-dimensional patterns have various applications including X-ray imaging and atom and particle trapping. Two- …

H0licow Vii: Cosmic Evolution Of The Correlation Between Black Hole Mass And Host Galaxy Luminosity, Xuheng Ding, Tommaso Treu, Sherry H. Suyu, Kenneth C. Wong, Takahiro Morishita, Daesong Park, Dominique Sluse, Matthew W. Auger, Adriano Agnello, Vardha Nicola Bennert, Thomas E. Collett

Physics

Strongly lensed active galactic nuclei (AGN) provide a unique opportunity to make progress in the study of the evolution of the correlation between the mass of supermassive black holes (M_BH⁠⁠) and their host galaxy luminosity (L_host). We demonstrate the power of lensing by analysing two systems for which state-of-the-art lens modelling techniques have been applied to deep Hubble Space Telescope imaging data. We use (i) the reconstructed images to infer the total and bulge luminosity of the host and (ii) published broad-line spectroscopy to estimate M_BH using the so-called virial method. We then enlarge …

Ambipolar Spin Diffusion In P-Type Gaas: A Case Where Spin Diffuses More Than Charge, F. Cadiz, V. Notot, J. Filipovic, Christopher P. Weber, L. Martinelli, A.C. H. Rowe, S. Arscott

Physics

We investigate the diffusion of charge and spin at 15 K in p-type GaAs, combining transient-grating and energy-resolved microluminescence measurements to cover a broad range of photoelectron density. At very low optical power, in a unipolar nondegenerate regime, charge and spin diffuse at the same rate, implying that the spin-drag effects are negligible. Upon increasing the photoelectron concentration up to about 1016 cm–3, the charge diffusion constant decreases because of ambipolar electrostatic interactions with the slower-diffusing holes while the spin diffusion constant is reduced only weakly by the ambipolar interaction. A further increase in the excitation power causes increases in …

Solar Powered Single-Axis Heliostat Active Solar Tracking Device, Mason Kyle Roberts

Physics

As a means of cooking food, the burning of biomass accounts for over 4 million premature deaths in third world countries (“Household Air Pollution and Health”). The focus of this project was to explore an alternative that could utilize focused sunlight to cook food. A solar tracker was designed to be affixed to a parabolic, reflective, tilted single axis heliostat to follow the sun throughout the day and focus the reflected light to the bottom of a cooking surface. This surface became hot enough to for the preparation of food or boiling/sterilization of water.

A goal for each project was …

Working With Cuore In Search For The Neutrinoless-Double Beta Decay, Kevin H. Phung

Physics

The neutrino, if found to be its own anti-particle, will reshape the Standard Model of physics. This paper will give some background information regarding CUORE’s experiment to discover the radioactive process known as neutrinoless double-beta decay, how their experiment works, and my own involvement in their research during the installation phase of the project in the summer of 2017.

On-Sight Shifting At The Cryogenic Underground Observatory For Rare Events, Aaron C. Wong

Physics

During the summer of 2016, four Cal Poly students traveled to Assergi, Italy to contribute to the CUORE collaboration which is in search of a rare process called neutrinoless double beta decay. If detected, neutrinoless double beta decay will make break throughs in particle and nuclear physics, and will be the first observation of lepton number violation. The Cal Poly students provided on-sight shifting support during the installation phase of the project. This is a breakdown of the physics behind CUORE and Cal Poly's contribution.

Optical Physics Of Rifle Scopes, Ryan Perry

Physics

Optical systems are typically consist of multiple lenses and mirrors and are used in a wide variety of fields. While there exist a variety of setups, there are a few key concepts that are at the core of all of them. These could be used from the most advanced scientific research to a simple magnifying glass. They are also used in industry and consumer products such as glasses and cameras. We are going to go over these key concepts and show how they apply to telescopes, or more specifically rifle scopes. First, we will go over Snell's Law of refraction …

Improvements For The T0c+ Geometry Of The Fast Interaction Trigger (Fit) Upgrade To Alice At The Cern Lhc, Noah Miller

Physics

The purpose of the ALICE experiment at CERN is to investigate the properties of the strongly interacting quark-gluon plasma formed in the high-energy collisions of lead nuclei in the CERN Large Hadron Collider. ALICE has been collecting data since 2009. The upcoming upgrade of the CERN LHC injectors during 2019-20 will boost the luminosity and the collision rate beyond the design parameters for several of the key ALICE detectors including the forward trigger detectors. The new Fast Interaction Trigger (FIT) will enable ALICE to discriminate beam-beam interactions with a 99% efficiency for the collisions generated by the LHC at a …

Investigation Of Peltier Devices For Refrigeration, Evan C. Drake

Physics

The purpose of our project was to characterize Peltier devices and determine if they were good candidates toward inexpensive off-grid solar powered refrigeration in poor countries. We measured the rate of cooling with a constant temperature thermal sink for different current inputs. Through numerous experiments we calculated the coefficient of performance for two different thermoelectric coolers (TECs) through a range of temperature differentials. In addition, we found the lowest temperature these Peltier chips could reach so that we could test the accuracy of the information provided by the manufacturers spec sheets. Overall the data gathered through our research is compelling …

My Contributions To The Cryogenic Underground Observatory For Rare Events Experiment And The Utilization Of Geant4 In Their Analysis, Kevin Armenta

Physics

First, a brief introduction and background of the basics of particle physics and the Standard Model is discussed in order to give context to nature of the neutrinoless double beta decay ($2\nu\beta\beta$) and why it is so interesting to particle physicists. Next, the Cryogenic Underground Observatory for Rare Events (CUORE) experiment is discussed in detail, explaining the rational behind the experimental setup and detection process. Finally, I conclude by discussing Geant4, an important software toolkit used in particle physics, and how it is utilized in the CUORE experiment.

Discovery And Follow-Up Observations Of The Young Type Ia Supernova 2016coj, Weikang Zheng, Alexei V. Filippenko, Jon Mauerhan, Melissa L. Graham, Vardha Nicola Bennert, Xiaofeng Wang

Physics

The Type Ia supernova (SN Ia) 2016coj in NGC 4125 (redshift z = 0.00452 ± 0.00006) was discovered by the Lick Observatory Supernova Search 4.9 days after the fitted first-light time (FFLT; 11.1 days before B-band maximum). Our first detection (prediscovery) is merely 0.6 ± 0.5 days after the FFLT, making SN 2016coj one of the earliest known detections of an SN Ia. A spectrum was taken only 3.7 hr after discovery (5.0 days after the FFLT) and classified as a normal SN Ia. We performed high-quality photometry, low- and high-resolution spectroscopy, and spectropolarimetry, finding that SN 2016coj is …

The Classical Limit Of Entropic Quantum Dynamics, Anthony V. Demme

Physics

The framework of entropic dynamics (ED) allows one to derive quantum mechanics as an application of entropic inference. In this work we derive the classical limit of quantum mechanics in the context of ED. Our goal is to find conditions so that the center of mass (CM) of a system of N particles behaves as a classical particle. What is of interest is that ~ remains finite at all steps in the calculation and that the classical motion is obtained as the result of a central limit theorem. More explicitly we show that if the system is sufficiently large, and …

Development, Implementation, And Validation Of A California Coastal Ocean Modeling, Data Assimilation, And Forecasting System, Yi Chao, John D. Farrara, Hongchun Zhang, Kevin Armenta, Luca Centurioni, Francisco Chavez, James B. Girton, Dan Rudnick, Ryan K. Walter

Physics

A three-dimensional, near real-time data-assimilative modeling system for the California coastal ocean is presented. The system consists of a Regional Ocean Modeling System (ROMS) forced by the North American Mesoscale Forecast System (NAM). The ocean model has a horizontal resolution of approximately three kilometers and utilizes a multi-scale three-dimensional variational (3DVAR) data assimilation methodology. The system is run in near real-time to produce a nowcast every six hours and a 72-hour forecast every day. The performance of this nowcast system is presented using results from a six-year period of 2009–2015.

The ROMS results are first compared with the assimilated data …

Extending The Calibration Of C Iv-Based Single-Epoch Black Hole Mass Estimators For Active Galactic Nuclei, Daeseong Park, Aaron J. Barth, Jong-Hak Woo, Matthew A. Malkan, Tommaso Treu, Vardha Nicola Bennert, Roberto J. Assef, Anna Pancoast

Physics

We provide an updated calibration of C iv broad emission line–based single-epoch (SE) black hole (BH) mass estimators for active galactic nuclei (AGNs) using new data for six reverberation-mapped AGNs at redshift with BH masses (bolometric luminosities) in the range ( erg s−1). New rest-frame UV-to-optical spectra covering 1150–5700 Å for the six AGNs were obtained with the Hubble Space Telescope (HST). Multicomponent spectral decompositions of the HST spectra were used to measure SE emission-line widths for the C iv, Mg ii, and Hβ lines, as well as continuum luminosities in the spectral region around each line. …

Projected Sensitivity Of The Supercdms Snolab Experiment, R. Agnese, A. J. Anderson, T. Aramaki, I. J. Arnquist, W. Baker, D. Barker, R. Basu Thakur, D. A. Bauer, A. Borgland, M. A. Bowles, P. L. Brink, R. Bunker, Blas Cabrera, D. O. Caldwell, R. Calkins, C. Cartaro, D. G. Cerdeño, H. Chagani, Y. Chen, J. Cooley, B. Cornell, P. Cushman, M. Daal, P.C. F. Di Stefano, T. Doughty, L. Esteban, S. Fallows, E. Figueroa-Feliciano, M. Fritts, G. Gerbier, M. Ghaith, G. L. Godfrey, S. R. Golwala, J. Hall, H. R. Harris, T. Hofer, D. Holmgren, Z. Hong, E. Hoppe, L. Hsu, M. E. Huber, V. Iyer, D. Jardin, A. Jastram, M. H. Kelsey, A. Kennedy, A. Kubik, N. A. Kurinsky, A. Leder, B. Loer, E. Lopez Asamar, P. Lukens, R. Mahapatra, V. Mandic, N. Mast, N. Mirabolfathi, R. A. Moffatt, J. D. Morales Mendoza, J. L. Orrell, S. M. Oser, K. Page, W. A. Page, R. Partridge, M. Pepin, A. Phipps, S. Poudel, M. Pyle, H. Qiu, W. Rau, P. Redl, A. Reisetter, A. Roberts, A. E. Robinson, H. E. Rogers, T. Saab, B. Sadoulet, J. Sander, K. Schneck, R. W. Schnee, B. Serfass, D. Speller, M. Stein, J. Street, H. A. Tanaka, D. Toback, R. Underwood, A. N. Villano, B. Von Krosigk, B. Welliver, J. S. Wilson, D. H. Wright, S. Yellin, J. J. Yen, Betty A. Young, X. Zhang, X. Zhao

Physics

SuperCDMS SNOLAB will be a next-generation experiment aimed at directly detecting low-mass (< 10 GeV/c²) particles that may constitute dark matter by using cryogenic detectors of two types (HV and iZIP) and two target materials (germanium and silicon). The experiment is being designed with an initial sensitivity to nuclear recoil cross sections ~ 1 x 10⁻⁴³ cm² for a dark matter particle mass of 1 GeV/c², and with capacity to continue exploration to both smaller masses and better sensitivities. The phonon sensitivity of the HV detectors will be sufficient to detect nuclear recoils from sub-GeV dark …

Room-Temperature Self-Powered Energy Photodetector Based On Optically Induced Seebeck Effect In Cd3As2, Niloufar Yavarishad, Tahereh Hosseini, Elaheh Kheirandish, Christopher P. Weber, Nikolai Kouklin

Physics

We demonstrate an intrinsically fast Seebeck-type metal–semimetal–metal infrared photodetector based on Cd₃As₂ crystals. The Seebeck voltage is induced under off-center illumination, leading to asymmetric temperature gradients and a net current flow. The room-temperature responsivity of the sensor is 0.27 mA/W. The photocurrent signal is readily registered at a modulation frequency of 6 kHz, and the intrinsic bandwidth of the sensor is predicted to approach the terahertz range. The photocurrent depends on the optical power and modulation frequency. Our study demonstrates that crystallineCd₃As₂ is a promising material for high-bandwidth and spectrally broad photosensing, imaging, and …

Space Telescope And Optical Reverberation Mapping Project. V. Optical Spectroscopic Campaign And Emission-Line Analysis For Ngc 5548, L. Pei, M. M. Fausnaugh, A. J. Barth, B. M. Peterson, Vardha Nicola Bennert, Y. Zu

Physics

We present the results of an optical spectroscopic monitoring program targeting NGC 5548 as part of a larger multiwavelength reverberation mapping campaign. The campaign spanned 6 months and achieved an almost daily cadence with observations from five ground-based telescopes. The Hβ and He ii λ4686 broad emission-line light curves lag that of the 5100 Å optical continuum by and , respectively. The Hβ lag relative to the 1158 Å ultraviolet continuum light curve measured by the Hubble Space Telescope is ~50% longer than that measured against the optical continuum, and the lag difference is consistent with the …

Developing An Imaging System To Monitor Atom Traps For Neutral Atom Quantum Computing, Jenna Valdez

Physics

Quantum computing exploits the laws of quantum mechanics to exponentially increase computing rate for certain processes. A realized quantum computer could break encryptions and simulate large quantum systems previously unbreakable and unattainable with classical computers. Neutral atom quantum computing is a viable candidate for building these devices that satisfies four of the five criteria for a successful quantum computer. We are exploring a novel method in creating neutral atom qubits that involves a magneto-optical trap and a dipole trap created in the diffraction pattern behind an array of pinholes. The magneto-optical trap works to cool the atoms and centralize them …

Fading Agn Candidates: Agn Histories And Outflow Signatures, William C. Keel, Chris J. Lintott, W. Peter Maksym, Vardha N. Bennert, S. Drew Chojnowski, Alexei Moiseev, Aleksandrina Smirnova, Kevin Schawinski, Lia F. Sartori, C. Megan Urry, Anna Pancoast, Mischa Schirmer, Bryan Scott, Charles Grant Showley, Kelsi Flatland

Physics

We consider the energy budgets and radiative history of eight fading active galactic nuclei (AGNs), identified from an energy shortfall between the requirements to ionize very extended (radius > 10 kpc) ionized clouds and the luminosity of the nucleus as we view it directly. All show evidence of significant fading on timescales of ≈50,000 yr. We explore the use of minimum ionizing luminosity Q_ion derived from photoionization balance in the brightest pixels in Hα at each projected radius. Tests using presumably constant Palomar–Green QSOs, and one of our targets with detailed photoionization modeling, suggest that we can derive useful …

Local Diurnal Wind‐Driven Variability And Upwelling In A Small Coastal Embayment, Ryan K. Walter, Emma C. Reid, Kristen A. Davis, Kevin Armenta, Kevin Merhoff, Nicholas J. Nidzieko

Physics

The oceanic response to high‐frequency local diurnal wind forcing is examined in a small coastal embayment located along an understudied stretch of the central California coast. We show that local diurnal wind forcing is the dominant control on nearshore temperature variability and circulation patterns. A complex empirical orthogonal function (CEOF) analysis of velocities in San Luis Obispo Bay reveals that the first‐mode CEOF amplitude time series, which accounts for 47.9% of the variance, is significantly coherent with the local wind signal at the diurnal frequency and aligns with periods of weak and strong wind forcing. The diurnal evolution of the …