150 research outputs found
Lightbulb moment: electricity in the YWCA scrapbook
2015 University Libraries Undergraduate Research Award Winner---Between 1915 and 1917 the Young Women’s Christian Association at the State Normal and Industrial College (presently the University of North Carolina at Greensboro) created a scrapbook that largely focused on summer retreats in Black Mountain, NC.1 Photographs of the members posed in groups along with more candid pictures showing the girls participating in a variety of outdoor activities dominate a majority of the pages. However, about three-quarters ofthe way through the scrapbook there is a conspicuous collage of clippings which relate to electrical lighting. Even more peculiar than its placement, is the fact that during the creation of the scrapbook, the lightbulb was nearing forty years old.2 However, electricity did not spread evenly or as quickly through different regions of the United States, and many people were not exposed to it in their domestic lives until the 1930s. Those who experienced electricity for thefirst time often responded with awe, and incorporated it into their ideas of progress and modernity. The electricity-centric clippings in the YWCA scrapbook demonstrate this, as they show a personalized view of the technology that illustrates the societal impact of lighting in the early 20th century
The Multi-Object, Fiber-Fed Spectrographs for SDSS and the Baryon Oscillation Spectroscopic Survey
We present the design and performance of the multi-object fiber spectrographs
for the Sloan Digital Sky Survey (SDSS) and their upgrade for the Baryon
Oscillation Spectroscopic Survey (BOSS). Originally commissioned in Fall 1999
on the 2.5-m aperture Sloan Telescope at Apache Point Observatory, the
spectrographs produced more than 1.5 million spectra for the SDSS and SDSS-II
surveys, enabling a wide variety of Galactic and extra-galactic science
including the first observation of baryon acoustic oscillations in 2005. The
spectrographs were upgraded in 2009 and are currently in use for BOSS, the
flagship survey of the third-generation SDSS-III project. BOSS will measure
redshifts of 1.35 million massive galaxies to redshift 0.7 and Lyman-alpha
absorption of 160,000 high redshift quasars over 10,000 square degrees of sky,
making percent level measurements of the absolute cosmic distance scale of the
Universe and placing tight constraints on the equation of state of dark energy.
The twin multi-object fiber spectrographs utilize a simple optical layout
with reflective collimators, gratings, all-refractive cameras, and
state-of-the-art CCD detectors to produce hundreds of spectra simultaneously in
two channels over a bandpass covering the near ultraviolet to the near
infrared, with a resolving power R = \lambda/FWHM ~ 2000. Building on proven
heritage, the spectrographs were upgraded for BOSS with volume-phase
holographic gratings and modern CCD detectors, improving the peak throughput by
nearly a factor of two, extending the bandpass to cover 360 < \lambda < 1000
nm, and increasing the number of fibers from 640 to 1000 per exposure. In this
paper we describe the original SDSS spectrograph design and the upgrades
implemented for BOSS, and document the predicted and measured performances.Comment: 43 pages, 42 figures, revised according to referee report and
accepted by AJ. Provides background for the instrument responsible for SDSS
and BOSS spectra. 4th in a series of survey technical papers released in
Summer 2012, including arXiv:1207.7137 (DR9), arXiv:1207.7326 (Spectral
Classification), and arXiv:1208.0022 (BOSS Overview
Net Charge Fluctuations in Au + Au Interactions at sqrt(s_NN) = 130 GeV
Data from Au + Au interactions at sqrt(s_NN) = 130 GeV, obtained with the
PHENIX detector at RHIC, are used to investigate local net charge fluctuations
among particles produced near mid-rapidity. According to recent suggestions,
such fluctuations may carry information from the Quark Gluon Plasma. This
analysis shows that the fluctuations are dominated by a stochastic distribution
of particles, but are also sensitive to other effects, like global charge
conservation and resonance decays.Comment: 6 pages, RevTeX 3, 3 figures, 307 authors, submitted to Phys. Rev.
Lett. on 21 March, 2002. Plain text data tables for the points plotted in
figures for this and previous PHENIX publications are (will be made) publicly
available at http://www.phenix.bnl.gov/phenix/WWW/run/phenix/papers.htm
Event-by-event fluctuations in Mean and Mean in sqrt(s_NN) = 130 GeV Au+Au Collisions
Distributions of event-by-event fluctuations of the mean transverse momentum
and mean transverse energy near mid-rapidity have been measured in Au+Au
collisions at sqrt(s_NN) = 130 GeV at RHIC. By comparing the distributions to
what is expected for statistically independent particle emission, the magnitude
of non-statistical fluctuations in mean transverse momentum is determined to be
consistent with zero. Also, no significant non-random fluctuations in mean
transverse energy are observed. By constructing a fluctuation model with two
event classes that preserve the mean and variance of the semi-inclusive p_T or
e_T spectra, we exclude a region of fluctuations in sqrt(s_NN) = 130 GeV Au+Au
collisions.Comment: 10 pages, RevTeX 3, 7 figures, 4 tables, 307 authors, submitted to
Phys. Rev. C on 22 March 2002. Plain text data tables for the points plotted
in figures for this and previous PHENIX publications are (will be made)
publicly available at
http://www.phenix.bnl.gov/phenix/WWW/run/phenix/papers.htm
Flow Measurements via Two-particle Azimuthal Correlations in Au + Au Collisions at sqrt(s_NN) = 130 GeV
Two particle azimuthal correlation functions are presented for charged
hadrons produced in Au + Au collisions at RHIC sqrt(s_NN) = 130 GeV. The
measurements permit determination of elliptic flow without event-by-event
estimation of the reaction plane. The extracted elliptic flow values v_2 show
significant sensitivity to both the collision centrality and the transverse
momenta of emitted hadrons, suggesting rapid thermalization and relatively
strong velocity fields. When scaled by the eccentricity of the collision zone,
epsilon, the scaled elliptic flow shows little or no dependence on centrality
for charged hadrons with relatively low p_T. A breakdown of this epsilon
scaling is observed for charged hadrons with p_T > 1.0 GeV/c for the most
central collisions.Comment: 6 pages, RevTeX 3, 4 figures, 307 authors, submitted to Phys. Rev.
Lett. on 11 April 2002. Plain text data tables for the points plotted in
figures for this and previous PHENIX publications are (will be made) publicly
available at http://www.phenix.bnl.gov/phenix/WWW/run/phenix/papers.htm
Measurement of the mid-rapidity transverse energy distribution from GeV Au+Au collisions at RHIC
The first measurement of energy produced transverse to the beam direction at
RHIC is presented. The mid-rapidity transverse energy density per participating
nucleon rises steadily with the number of participants, closely paralleling the
rise in charged-particle density, such that E_T / N_ch remains relatively
constant as a function of centrality. The energy density calculated via
Bjorken's prescription for the 2% most central Au+Au collisions at
sqrt(s_NN)=130 GeV is at least epsilon_Bj = 4.6 GeV/fm^3 which is a factor of
1.6 larger than found at sqrt(s_NN)=17.2 GeV (Pb+Pb at CERN).Comment: 307 authors, 6 pages, 4 figures, 1 table, submitted to PRL 4/18/2001;
revised version submitted to PRL 5/24/200
Centrality Dependence of Charged Particle Multiplicity in Au-Au Collisions at sqrt(s_NN)=130 GeV
We present results for the charged-particle multiplicity distribution at
mid-rapidity in Au - Au collisions at sqrt(s_NN)=130 GeV measured with the
PHENIX detector at RHIC. For the 5% most central collisions we find
. The results,
analyzed as a function of centrality, show a steady rise of the particle
density per participating nucleon with centrality.Comment: 307 authors, 43 institutions, 6 pages, 4 figures, 1 table Minor
changes to figure labels and text to meet PRL requirements. One author added:
M. Hibino of Waseda Universit
Centrality dependence of pi^[+/-], K^[+/-], p and p-bar production from sqrt(s_NN)=130 GeV Au + Au collisions at RHIC
Identified pi^[+/-] K^[+/-], p and p-bar transverse momentum spectra at
mid-rapidity in sqrt(s_NN)=130 GeV Au-Au collisions were measured by the PHENIX
experiment at RHIC as a function of collision centrality. Average transverse
momenta increase with the number of participating nucleons in a similar way for
all particle species. The multiplicity densities scale faster than the number
of participating nucleons. Kaon and nucleon yields per participant increase
faster than the pion yields. In central collisions at high transverse momenta
(p_T greater than 2 GeV/c), anti-proton and proton yields are comparable to the
pion yields.Comment: 6 pages, 3 figures, 1 table, 307 authors, accepted by Phys. Rev.
Lett. on 9 April 2002. This version has minor changes made in response to
referee Comments. Plain text data tables for the points plotted in figures
for this and previous PHENIX publications are publicly available at
http://www.phenix.bnl.gov/phenix/WWW/run/phenix/papers.htm
Proximity effect at superconducting Sn-Bi2Se3 interface
We have investigated the conductance spectra of Sn-Bi2Se3 interface junctions
down to 250 mK and in different magnetic fields. A number of conductance
anomalies were observed below the superconducting transition temperature of Sn,
including a small gap different from that of Sn, and a zero-bias conductance
peak growing up at lower temperatures. We discussed the possible origins of the
smaller gap and the zero-bias conductance peak. These phenomena support that a
proximity-effect-induced chiral superconducting phase is formed at the
interface between the superconducting Sn and the strong spin-orbit coupling
material Bi2Se3.Comment: 7 pages, 8 figure
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