18452656
Testing and Data Reduction of the Chinese Small Telescope Array (CSTAR ) for Dome A, Antarctica
The Chinese Small Telescope Array (CSTAR) is the first Chinese astronomical instrument on the Antarctic ice cap. The low temperature and low pressure testing of the data acquisition system was carried out in a laboratory refrigerator and on the 4500 m Pamirs high plateau, respectively. The results from the final four nights of test observations demonstrated that CSTAR was ready for operation at Dome A, Antarctica. In this paper, we present a description of CSTAR and the performance derived from the test observations.
9327494
The sky brightness and transparency in i-band at Dome A, Antarctica
The i-band observing conditions at Dome A on the Antarctic plateau have been investigated using data acquired during 2008 with the Chinese Small Telescope ARray. The sky brightness, variations in atmospheric transparency, cloud cover, and the presence of aurorae are obtained from these images. The median sky brightness of moonless clear nights is 20.5 mag arcsec^{-2} in the SDSS $i$ band at the South Celestial Pole (which includes a contribution of about 0.06 mag from diffuse Galactic light). The median over all Moon phases in the Antarctic winter is about 19.8 mag arcsec^{-2}. There were no thick clouds in 2008. We model contributions of the Sun and the Moon to the sky background to obtain the relationship between the sky brightness and transparency. Aurorae are identified by comparing the observed sky brightness to the sky brightness expected from this model. About 2% of the images are affected by relatively strong aurorae.
54757692
The First Release of the CSTAR Point Source Catalog from Dome A, Antarctica
In 2008 January the twenty-fourth Chinese expedition team successfully deployed the Chinese Small Telescope ARray (CSTAR) to Dome A, the highest point on the Antarctic plateau. CSTAR consists of four 14.5 cm optical telescopes, each with a different filter (g, r, i, and open) and has a 4.5° × 4.5° field of view (FOV). It operates robotically as part of the Plateau Observatory, PLATO, with each telescope taking an image every ~30 s throughout the year whenever it is dark. During 2008, CSTAR 1 performed almost flawlessly, acquiring more than 0.3 million i-band images for a total integration time of 1728 hr during 158 days of observations. For each image taken under good sky conditions, more than 10,000 sources down to ~16th magnitude could be detected. We performed aperture photometry on all the sources in the field to create the catalog described herein. Since CSTAR has a fixed pointing centered on the south celestial pole (decl. = -90°), all the sources within the FOV of CSTAR were monitored continuously for several months. The photometric catalog can be used for studying any variability in these sources, and for the discovery of transient sources such as supernovae, gamma-ray bursts, and minor planets.
119176140
A general relativistic external Compton-scattering model for TeV emission from M87
M87 is the first detected non-blazar extragalactic Tera-Ele ctron-Volt (TeV) source with rapid variation and very flat spectrum in the TeV band. To explain the two-peaks in the spectral energy distribution (SED) of the nucleus of M87 which is similar to those of blazars, the most commonly adopted models are the synchrotron self-Compton scattering (SSC) models and the external inverse Compton scattering (EIC) models. Considering that there is no correlated variation in the soft band (from r adio to X-ray) matching the TeV variation, and the TeV sources should not suffer from the γγ absorption due to the flat TeV spectrum, the EIC models are advantageous in modeling the TeV emission from M87. In this paper, we propose a self-consistent EIC model to explain the flat TeV spectrum of M87 within the framework of fully general relativity, where the background soft photons are from the advection-dominated accretion flo w (ADAF) around the central black hole, and the high energy electrons are from the mini-jets which are powered by the magnetic reconnection in the main jet (Giannios et al. 2010). In our model, both the TeV flares obser ved in the years of 2005 and 2008 could be well explained: the γγ absorption for TeV photons is very low, even inside the region very close to the black hole 20Rg ∼ 50Rg; at the same region, the average EIC cooling time (∼ 10 2 ∼ 10 3 s) is short, which is consistent with the observed time scale of TeV variation. Furthermore, we also discuss the possibility that the accompanying X-ray flare in 2008 is due to the direct synchrotron radiation of the mini-jets. Subject headings:black hole physics — galaxies: individual (M87)
125771026
Letter of intent for the study of CP violation and heavy flavor physics at PEP-II
95305160
Synthesis and characterization of nanofibrous sodium manganese oxide with a 2 x 4 tunnel structure
Sodium manganese oxide octahedral molecular sieves with a 2 × 4 tunnel structure (Na−2 × 4) have been hydrothermally synthesized from Na−birnessite materials at low temperatures and pressures. The synthetic template materials, the pH value of the medium, and the autoclaved temperature are critical in the synthesis. Sodium salts, such as NaCl, NaNO3, and Na2SO4, are good templates for Na−2 × 4. In strong basic solution or below 160 °C, Na−birnessite does not transform to the Na−2 × 4 structure. TEM images show the synthesized Na−2 × 4 is made up of thin slablike single crystals elongated along the b axis. The formula of Na−2 × 4 can be written as Na0.33M M O2·xH2O, and it is monoclinic with space group C2/m. The unit cell parameters (a, b, c, and β) for Na−2 × 4 are 14.434(5) A, 2.849(7) A, 23.976(6) A, and 98.18°, respectively. These data for Na−2 × 4 are slightly different from the data for Rb−2 × 4 synthesized under high pressure and high temperature, which were reported by Rziha et al. (Eur. J. Miner. ...
122834865
Performance of CMS hadron calorimeter timing and synchronization using test beam, cosmic ray, and LHC beam data
This paper discusses the design and performance of the time measurement technique and of the synchronization systems of the CMS hadron calorimeter. Time measurement performance results are presented from test beam data taken in the years 2004 and 2006. For hadronic showers of energy greater than 100 GeV, the timing resolution is measured to be about 1.2 ns. Time synchronization and out-of-time background rejection results are presented from the Cosmic Run At Four Tesla and LHC beam runs taken in the Autumn of 2008. The inter-channel synchronization is measured to be within ±2 ns.
123461752
Neutron-deuteron differential cross sections at 35.0 and 46.3 MeV
Differential cross sections have been measured for $\mathrm{nd}$ and $\mathrm{pd}$ scattering at 35.0 and 46.3 MeV. Only cross sections for c.m. angles \ensuremath{\gtrsim} 90\ifmmode^\circ\else\textdegree\fi{} have been measured in this work, which is in part a higher-precision remeasurement of earlier $\mathrm{nd}$ cross sections and whose main purpose has been to check possible $\mathrm{nd}\ensuremath{-}\mathrm{pd}$ differences which appeared in the earlier measurements at 36.0 and 46.3 MeV. Absolute $\mathrm{nd}$ cross sections of $\ensuremath{\simeq}5%$ precision, obtained by normalization to precision $\mathrm{np}$ cross sections, are compared with absolute $\mathrm{pd}$ cross sections measured at the University of California at Los Angeles. The differences in this comparison and in the $\mathrm{nd}\ensuremath{-}\mathrm{pd}$ relative cross sections measured here are smaller than indicated by the previous measurements. However, some systematic differences do appear to exist at angles near the cross-section minima and beyond.