Physical Sciences and Mathematics Commons^™

Directly Photoexcited Dirac And Weyl Fermions In Zrsis And Nbas, Christopher P. Weber, Leslie M. Schoop, Stuart S. P. Parkin, Robert C. Newby, Alex Nateprov, Bettina Lotsch, Bala Murali Krishna Mariserla, J. Matthew Kim, Keshav M. Dani, Hans A. Bechtel, Ernerst Arushanov, Mazhar Ali

Physics

We report ultrafast optical measurements of the Dirac line-node semimetal ZrSiS and the Weyl semimetal NbAs, using mid-infrared pump photons from 86 meV to 500 meV to directly excite Dirac and Weyl fermions within the linearly dispersing bands. In NbAs, the photoexcited Weyl fermions initially form a non-thermal distribution, signified by a brief spike in the differential reflectivity whose sign is controlled by the relative energy of the pump and probe photons. In ZrSiS, electron-electron scattering rapidly thermalizes the electrons, and the spike is not observed. Subsequently, hot carriers in both materials cool within a few picoseconds. This cooling, as …

The Santa Clara, 2018-11-08, Santa Clara University

The Santa Clara

No abstract provided.

The Santa Clara, 2018-11-01, Santa Clara University

The Santa Clara

No abstract provided.

The Santa Clara, 2018-10-25, Santa Clara University

The Santa Clara

No abstract provided.

The Santa Clara, 2018-10-18, Santa Clara University

The Santa Clara

No abstract provided.

The Santa Clara, 2018-10-11, Santa Clara University

The Santa Clara

No abstract provided.

Using Coherent Phonons For Ultrafast Control Of The Dirac Node Of Srmnsb2, Christopher P. Weber, Madison G. Masten, Thomas C. Ogloza, Bryan S. Berggren, Michael K. L. Man, Keshav M. Dani, Jinyu Liu, Zhiqiang Mao, Dennis D. Klug, Adebayo A. Adeleke, Yansun Yao

Physics

SrMnSb₂ is a candidate Dirac semimetal whose electrons near the Y point have the linear dispersion and low mass of a Dirac cone. Here we demonstrate that ultrafast, 800-nm optical pulses can launch coherent phonon oscillations in Sr_0.94Mn_0.92Sb₂, particularly an A_g mode at 4.4 THz. Through first-principles calculations of the electronic and phononic structure of SrMnSb₂, we show that high-amplitude oscillations of this mode would displace the atoms in a way that transiently opens and closes a gap at the node of the Dirac cone. The ability to control the …

The Santa Clara, 2018-10-04, Santa Clara University

The Santa Clara

No abstract provided.

Santa Clara Magazine, Volume 60 Number 1, Fall 2018, Santa Clara University

Santa Clara Magazine

24 - FOUND IN TRANSLATION The Pulitzer for editorial cartooning recognizes the tale of two Syrian refugee families. Here’s who translated their story. By Tracy Seipel and Tina Vossugh.

26 - LEGENDS OF THE COURT A pair of Bronco hoops legends: Steve Nash ’96, welcome to the Basketball Hall of Fame! Kurt Rambis ’80, on big-time break-ins—and a fan club like no other. Words by Mark Purdy and Sam Farmer. Illustrations by Victor Juhasz.

34 - A JOURNEY THROUGH THE HOLY LAND Israel, from a hazy gray sea to the House of Bread to the Hill of the Skull. Learning …

The Santa Clara, 2018-09-27, Santa Clara University

The Santa Clara

No abstract provided.

The Santa Clara, 2018-09-20, Santa Clara University

The Santa Clara

No abstract provided.

Structural And Wetting Properties Of Nature's Finest Silks (Order Embioptera), Grace Y. Stokes, Evangelea N. Dicicco, Trevor J. Moore, Vivian C. Cheng, Kira Y. Wheeler, John Soghigian, Richard P. Barber Jr., Janice Edgerly-Rooks

Physics

Insects from the order Embioptera (webspinners) spin silk fibres which are less than 200 nm in diameter. In this work, we characterized and compared the diameters of single silk fibres from nine species—Antipaluria urichi, Pararhagadochir trinitatis, Saussurembia calypso, Diradius vandykei, Aposthonia ceylonica, Haploembia solieri, H. tarsalis, Oligotoma nigra and O. saundersii. Silk from seven of these species have not been previously quantified. Our studies cover five of the 10 named taxonomic families and represent about one third of the known taxonomic family-level diversity in the order Embioptera. Naturally spun silk varied …

Energy Loss Due To Defect Formation From 206Pb Recoils In Supercdms Germanium Detectors, R. Agnese, T. Aralis, T. Aramaki, I. J. Arnquist, E. Azadbakht, W. Baker, S. Banik, D. Barker, D. A. Bauer, T. Binder, M. A. Bowles, P. L. Brink, R. Bunker, B. Cabrera, R. Calkins, D. G. Cerdeno, Y.-Y. Chang, J. Cooley, B. Cornell, P. Cushman, P. C. F. Di Stefano, T. Doughty, E. Fascione, E. Figueroa-Feliciano, C. W. Fink, M. Fritts, G. Gerbier, R. Germond, M. Ghaith, S. R. Golwala, H. R. Harris, Z. Hong, E. W. Hoppe, L. Hsu, M. E. Huber, V. Iyer, D. Jardin, C. Jena, M. H. Kelsey, A. Kennedy, A. Kubik, N. A. Kurinsky, R. E. Lawrence, B. Loer, E. Lopez Asamar, P. Lukens, D. Macdonell, R. Mahapatra, V. Mandic, N. Mast, E. H. Miller, N. Mirabolfathi, B. Mohanty, J. D. Morales Mendoza, J. Nelson, J. L. Orrell, S. M. Oser, W. A. Page, R. Partridge, M. Pepin, F. Ponce, S. Poudel, M. Pyle, H. Qui, W. Rau, A. Reisetter, T. Ren, T. Reynolds, A. Roberts, A. E. Robinson, H. E. Rogers, T. Saab, B. Sadoulet, J. Sander, A. Scarff, R. W. Schnee, S. Scorza, K. Senapati, B. Serfass, D. Speller, M. Stein, J. Street, H. A. Tanaka, D. Toback, R. Underwood, A. N. Villano, B. Von Krosigk, S. L. Watkins, J. S. Wilson, M. J. Wilson, J. Winchell, D. H. Wright, S. Yellin, Betty A. Young, X. Zhang, X. Xhao

Physics

The Super Cryogenic Dark Matter Search experiment (SuperCDMS) at the Soudan Underground Laboratory studied energy loss associated with Frenkel defect formation in germanium crystals at mK temperatures using in situ ²¹⁰Pb sources. We examine the spectrum of ²⁰⁶Pb nuclear recoils near its expected 103 keV endpoint energy and determine an energy loss of (6.08±0.18) %, which we attribute to defect formation. From this result and using TRIM simulations, we extract the first experimentally determined average displacement threshold energy of (19.7^+0.6_−0.5) eV for germanium. This has implications for the analysis thresholds of future germanium-based dark matter …

First Dark Matter Constraints From A Supercdms Single-Charge Sensitive Detector, R. Agnese, T. Aralis, T. Aramaki, I. J. Arnquist, E. Azadbakht, W. Baker, S. Banik, D. Barker, S. Banik, D. Barker, D. A. Bauer, T. Binder, M. A. Bowles, P. L. Brink, R. Bunker, Blas Cabrera, R. Calkins, C. Cartaro, D. G. Cerdeño, Y. Y. Chang, J. Cooley, B. Cornell, P. Cushman, P. C. F. Di Stefano, T. Doughty, E. Fascione, E. Figueroa-Feliciano, C. Fink, M. Fritts, G. Gerbier, R. Germond, M. Ghaith, S. R. Golwala, H. R. Harris, Z. Hong, E. W. Hoppe, L. Hsu, M. E. Huber, V. Iyers, D. Jardin, C. Jena, M. H. Kelsey, A. Kennedy, A. Kubik, N. A. Kurinsky, R. E. Lawrence, J. V. Leyva, B. Loer, E. Lopez Asamar, P. Lukens, D. Macdonell, R. Mahapatra, V. Mandic, N. Mast, E. H. Miller, N. Mirabolfathi, B. Mohanty, J. D. Morales Mendoza, J. Nelson, J. L. Orrell, S. M. Oser, W. A. Page, R. Partridge, M. Pepin, A. Phipps, F. Ponce, S. Poudel, M. Pyle, H. Qui, W. Rau, A. Reisetter, T. Reynolds, A. Roberts, A. E. Robinson, H. E. Rogers, R. K. Romani, T. Saab, B. Sadoulet, J. Sander, A. Scarff, R. W. Schnee, S. Scorza, K. Senapati, B. Serfass, J. So, D. Speller, C. Stanford, M. Stein, J. Street, H. A. Tanaka, D. Toback, R. Underwood, A. N. Villano, B. Von Krosigk, S. L. Watkins, J. S. Wilson, M. J. Wilson, J. Winchell, D. H. Wright, S. Yellin, Betty A. Young, X. Zhang, X. Zhao

Physics

We present the first limits on inelastic electron-scattering dark matter and dark photon absorption using a prototype SuperCDMS detector having a charge resolution of 0.1 electron-hole pairs (CDMS HVeV, a 0.93 gram CDMS HV device). These electron-recoil limits significantly improve experimental constraints on dark matter particles with masses as low as 1 MeV/c². We demonstrate a sensitivity to dark photons competitive with other leading approaches but using substantially less exposure (0.49 gram days). These results demonstrate the scientific potential of phonon-mediated semiconductor detectors that are sensitive to single electronic excitations.

Santa Clara Magazine, Volume 59 Number 2, 3, 4, August 2018 [Print Issues V. 58:2, 3, 4], Santa Clara University

Santa Clara Magazine

3 - GOOOAL! By Giannina Ong ’18

4 - LOVE, ARMAND Letters from a freshman to his widowed mother from a century ago

Residential Zoning And Near-Roadway Air Pollution: An Analysis Of Los Angeles, C. J. Gabbe

Environmental Studies and Sciences

Air pollution from motor vehicles harms the health of those who live near freeways and other high-traffic roads. Land use regulations may permit, prohibit, or impose special conditions on housing near major roadways. This paper answers two questions: First, how is residential development near major roadways regulated? Second, how common are zoning changes near major roadways, and what factors explain these changes? This paper compares the zoning designations of near-roadway parcels with others in the city, and uses two sets of logistic regression models to analyze near-roadway zoning. The results show that residential development is permitted on most near-roadway parcels, …

Applying Computer Algebra Systems In Approximating The Trigonometric Functions, Le Phuong Quan, Thái Ahn Nhan

Mathematics and Computer Science

We propose numerical algorithms which can be integrated with modern computer algebra systems in a way that is easily implemented to approximate the sine and cosine functions with an arbitrary accuracy. Our approach is based on Taylor’s expansion about a point having a form of kp, k ∈ ℤ and p = π/2 , and being chosen such that it is closest to the argument. A full error analysis, which takes advantage of current computer algebra systems in approximating π with a very high accuracy, of our proposed methods is provided. A numerical integration application is performed to demonstrate the …

Music From Vibrating Wallpaper, Frank A. Farris

Mathematics and Computer Science

Wallpaper patterns have been shown to be decomposable into standing waves of plane vibrations [6]. Previously unexplored are the sounds that arise from these vibrations. The main result of this paper is that each wallpaper type (square, hexagonal, rectangular, generic) has its own distinctive family of pitches relative to a fundamental. We review the method to make wallpaper with wave functions and describe new musical scales for each type, including initial attempts to use the scales: a movie showing vibrations of wallpaper patterns with 3- and 6-fold symmetry inspired a new piece by American composer William Susman, commissioned by the …

The Santa Clara, 2018-05-24, Santa Clara University

The Santa Clara

No abstract provided.

The Santa Clara, 2018-05-17, Santa Clara University

The Santa Clara

No abstract provided.

The Santa Clara, 2018-05-10, Santa Clara University

The Santa Clara

No abstract provided.

The Santa Clara, 2018-05-03, Santa Clara University

The Santa Clara

No abstract provided.

The Santa Clara, 2018-04-26, Santa Clara University

The Santa Clara

No abstract provided.

The Santa Clara, 2018-04-19, Santa Clara University

The Santa Clara

No abstract provided.

The Santa Clara, 2018-04-12, Santa Clara University

The Santa Clara

No abstract provided.

Time-Dependent Efficiency Measurements Of Polymer Solar Cells With Dye Additives: Unexpected Initial Increase Of Efficiency, Kyle J. Bandaccari, Grace E. Chesmore, Mitchel Bugaj, Parisa Tajalli-Tehrani Valverde, Richard P. Barber Jr., Brian J. Mcnelis

Physics

We report the effects of the addition of two azo-dye additives on the time-dependent efficiency of polymer solar cells. Although the maximum efficiencies of devices containing different amounts of dye do not vary greatly over the selected concentration range, the time dependence results reveal a surprising initial increase in efficiency in some samples. We observe this effect to be correlated with a leakage current, although a specific mechanism is not yet identified. We also present the measured lifetimes of these solar cells, and find that variations in dye concentrations produce a small effect at most. Characterization of the bulk heterojunction …

The Santa Clara, 2018-04-05, Santa Clara University

The Santa Clara

No abstract provided.

Santa Clara Magazine, Volume 59 Number 1, Spring 2018, Santa Clara University

Santa Clara Magazine

22 - TRUST ME After decades of declining trust in journalism, here’s some good news. Introducing the Trust Project. By Steven Boyd Saum and Deborah Lohse. Illustrations by Franziska Barczyk.

28 - NOBEL BEGINNINGS Santa Clara Professor Hersh Shefrin, fellow economist Richard Thaler, and the beginning of the fight to have behavioral economics taken seriously. There was yelling involved. By Deborah Lohse. Illustrations by Paul Blow.

32 - AFTERMATH OF DISASTER When fire or flood, wind or tremor strikes, what do you make of what’s been lost? How do you help others put their lives back together? Stories from the …

The Santa Clara, 2018-03-01, Santa Clara University

The Santa Clara

No abstract provided.

The Santa Clara, 2018-02-22, Santa Clara University

The Santa Clara

No abstract provided.