119266289
THE Pan-STARRS1 PHOTOMETRIC SYSTEM
The Pan-STARRS1 survey is collecting multi-epoch, multi-color observations of the sky north of declination –30° to unprecedented depths. These data are being photometrically and astrometrically calibrated and will serve as a reference for many other purposes. In this paper, we present our determination of the Pan-STARRS1 photometric system: g P1, r P1, i P1, z P1, y P1, and w P1. The Pan-STARRS1 photometric system is fundamentally based on the Hubble Space Telescope Calspec spectrophotometric observations, which in turn are fundamentally based on models of white dwarf atmospheres. We define the Pan-STARRS1 magnitude system and describe in detail our measurement of the system passbands, including both the instrumental sensitivity and atmospheric transmission functions. By-products, including transformations to other photometric systems, Galactic extinction, and stellar locus, are also provided. We close with a discussion of remaining systematic errors.
118552433
The First Very Long Baseline Interferometric Seti Experiment
The first Search for Extra-Terrestrial Intelligence (SETI) conducted with very long baseline interferometry (VLBI) is presented. By consideration of the basic principles of interferometry, we show that VLBI is efficient at discriminating between SETI signals and human generated radio frequency interference (RFI). The target for this study was the star Gliese 581, thought to have two planets within its habitable zone. On 2007 June 19, Gliese 581 was observed for 8 hr at 1230-1544 MHz with the Australian Long Baseline Array. The data set was searched for signals appearing on all interferometer baselines above five times the noise limit. A total of 222 potential SETI signals were detected and by using automated data analysis techniques were ruled out as originating from the Gliese 581 system. From our results we place an upper limit of 7 MW Hz–1 on the power output of any isotropic emitter located in the Gliese 581 system within this frequency range. This study shows that VLBI is ideal for targeted SETI including follow-up observations. The techniques presented are equally applicable to next-generation interferometers, such as the long baselines of the Square Kilometre Array.
119209508
HIP 38939B: A NEW BENCHMARK T DWARF IN THE GALACTIC PLANE DISCOVERED WITH Pan-STARRS1
We report the discovery of a wide brown dwarf companion to the mildly metal-poor ([Fe/H] = –0.24), low Galactic latitude (b = 188) K4V star HIP 38939. The companion was discovered by its common proper motion with the primary and its red optical (Pan-STARRS1) and blue infrared (Two Micron All Sky Survey) colors. It has a projected separation of 1630 AU and a near-infrared spectral type of T4.5. As such it is one of only three known companions to a main-sequence star which have early/mid T spectral types of (the others being HN Peg B and e Indi B). Using chromospheric activity we estimate an age for the primary of 900±1900 600 Myr. This value is also in agreement with the age derived from the star's weak ROSAT detection. Comparison with evolutionary models for this age range indicates that HIP 38939B falls in the mass range 38 ± 20 M Jup with an effective temperature range of 1090 ± 60 K. Fitting our spectrum with atmospheric models gives a best-fitting temperature of 1100 K. We include our object in an analysis of the population of benchmark T dwarfs and find that while older atmospheric models appeared to overpredict the temperature of the coolest objects compared to evolutionary models, more recent atmospheric models provide better agreement.
9863216
OBSERVATIONAL AND DYNAMICAL CHARACTERIZATION OF MAIN-BELT COMET P/2010 R2 (La Sagra)
We present observations of the recently discovered comet-like main-belt object P/2010 R2 (La Sagra) obtained by Pan-STARRS1 and the Faulkes Telescope-North on Haleakala in Hawaii, the University of Hawaii 2.2 m, Gemini-North, and Keck I telescopes on Mauna Kea, the Danish 1.54 m telescope (operated by the MiNDSTEp consortium) at La Silla, and the Isaac Newton Telescope on La Palma. An antisolar dust tail is observed to be present from 2010 August through 2011 February, while a dust trail aligned with the object's orbit plane is also observed from 2010 December through 2011 August. Assuming typical phase darkening behavior, P/La Sagra is seen to increase in brightness by >1 mag between 2010 August and December, suggesting that dust production is ongoing over this period. These results strongly suggest that the observed activity is cometary in nature (i.e., driven by the sublimation of volatile material), and that P/La Sagra is therefore the most recent main-belt comet to be discovered. We find an approximate absolute magnitude for the nucleus of HR = 17.9 ± 0.2 mag, corresponding to a nucleus radius of ~0.7 km, assuming an albedo of p = 0.05. Comparing the observed scattering surface areas of the dust coma to that of the nucleus when P/La Sagra was active, we find dust-to-nucleus area ratios of Ad /AN = 30-60, comparable to those computed for fellow main-belt comets 238P/Read and P/2008 R1 (Garradd), and one to two orders of magnitude larger than for two other main-belt comets (133P/Elst-Pizarro and 176P/LINEAR). Using optical spectroscopy to search for CN emission, we do not detect any conclusive evidence of sublimation products (i.e., gas emission), finding an upper limit CN production rate of Q CN 100 Myr, suggesting that it is likely native to its current location and that its composition is likely representative of other objects in the same region of the main belt, though the relatively close proximity of the 13:6 mean-motion resonance with Jupiter and the (3,–2,–1) three-body mean-motion resonance with Jupiter and Saturn mean that dynamical instability on larger timescales cannot be ruled out.
53626181
Ultra-bright optical transients are linked with type IC supernovae.
Recent searches by unbiased, wide-field surveys have uncovered a group of extremely luminous optical transients. The initial discoveries of SN 2005ap by the Texas Supernova Search and SCP-06F6 in a deep Hubble pencil beam survey were followed by the Palomar Transient Factory confirmation of host redshifts for other similar transients. The transients share the common properties of high optical luminosities (peak magnitudes ~-21 to -23), blue colors, and a lack of H or He spectral features. The physical mechanism that produces the luminosity is uncertain, with suggestions ranging from jet-driven explosion to pulsational pair instability. Here, we report the most detailed photometric and spectral coverage of an ultra-bright transient (SN 2010gx) detected in the Pan-STARRS 1 sky survey. In common with other transients in this family, early-time spectra show a blue continuum and prominent broad absorption lines of O II. However, about 25 days after discovery, the spectra developed type Ic supernova features, showing the characteristic broad Fe II and Si II absorption lines. Detailed, post-maximum follow-up may show that all SN 2005ap and SCP-06F6 type transients are linked to supernovae Ic. This poses problems in understanding the physics of the explosions: there is no indication from late-time photometry that the luminosity is powered by 56Ni, the broad light curves suggest very large ejected masses, and the slow spectral evolution is quite different from typical Ic timescales. The nature of the progenitor stars and the origin of the luminosity are intriguing and open questions.
41180894
PHOTOMETRIC CALIBRATION OF THE FIRST 1.5 YEARS OF THE PAN-STARRS1 SURVEY
We present a precise photometric calibration of the first 1.5 years of science imaging from the PanSTARRS1 survey (PS1), an ongoing optical survey of the entire sky north of declination −30 ◦ in five bands. Building on the techniques employed by Padmanabhan et al. (2008) in the Sloan Digital Sky Survey (SDSS), we use repeat PS1 observations of stars to perform the relative calibration of PS1 in each of its five bands, solving simultaneously for the system throughput, the atmospheric transparency, and the large-scale detector flat field. Both internal consistency tests and comparison against the SDSS indicate that we achieve relative precision of < 10 mmag in g, r, and iP1, and ∼ 10 mmag in z and yP1. The spatial structure of the differences with the SDSS indicates that errors in both the PS1 and SDSS photometric calibration contribute similarly to the differences. The analysis suggests that both the PS1 system and the Haleakala site will enable < 1% photometry over much of the sky. Subject headings: Surveys: Pan-STARRS1
119883102
Aspects of the bonding and insulation of a large superconducting solenoid
Abstract The bonding and insulation of a large superconducting solenoid is investigated. The techniques of ground-plane and inter-turn insulation, preparation of pre-impregnated glass tape, conductor bonding and conductor end turn insulation are examined.
107773393
Proposed Magnet Alignment Changes for AP-1
AP-1 was built to connect the Antiproton Source with the Main Ring accelerator. The beamline was designed to support modes of operation at both 8 GeV and 120 GeV kinetic energy. During the days of Main Ring operation, 120 GeV beam was extracted through the field region of a Lambertson at F-17 and transported approximately 174 meters to the production target. This 'pbar production' mode required a lattice that would focus the proton beam to a small spot size on the target to maximize antiproton yield. The AP-1 line would also be reconfigured to operate at 8 GeV to support antiproton transfers and tuning cycles with protons. The AP-1 line is also connected to the Accumulator via AP-3, so the lattices of these beamlines needed to be compatible. After the Main Injector was built to replace the Main Ring, a beamline was required to connect it with the Antiproton Source. Designers chose to combine beam transfers of 150 GeV protons to the Tevatron, 120 GeV protons to AP-1, 120 GeV protons to Switchyard and 8 GeV proton tune-up or antiproton transfers via AP-1 into the P1 and P2 lines. The P2 line resides in the Main Ring tunnel enclosure betweenmore » F-0 and F-17 and utilizes original Main Ring magnets. The lattice was designed to duplicate the Twiss parameters of the old Main Ring at F-17, including the large horizontal beta and dispersion functions. The addition of the P1 and P2 lines add almost an additional 1,000 meters and an extra Lambertson magnet (at F0) to beam transfers to and from the Main Injector versus the Main Ring. Although Lambertson magnets are still used to extract beam from the Main Injector, the Lambertson at F-17 was no longer required. Unfortunately, the limited aperture C-magnets at F-17 remained, necessitated by the P3 line which is intended to provide beam to Switchyard for future 'Meson 120' operation. The C-magnets are one of the limiting horizontal apertures in the AP-1 line due to the combination of small physical aperture and the large horizontal beta and dispersion functions. Most of the AP-1 magnets were originally used in Switchyard. Apertures of these magnets are adequate for high energy operation, but have apertures that are smaller than magnets traditionally used in other 8 GeV transfer lines. This makes the AP-1 line unusually sensitive to alignment and steering errors. In addition, the lattice constraints imposed by the beamlines attached to AP-1 does not allow much freedom in suppressing the lattice functions at key locations to reduce the beam size.« less
119416196
Parity and the spin—statistics connection
A simple demonstration of the spin—statistics connection for general causal fields is obtained by using the parity operation to exchange spatial coordinates in the scalar product of a locally commuting field operator, evaluated at position x, with the same field operator evaluated at − x, at equal times.
135541324
Irradiation damage studies of some epoxy resin systems of reduced viscosity.
Post irradiation mechanical propert ies are given for a number of epoxY materials, inoluding some glyci~l amine resin systems having reduced vi soosities. Chemical Technology Group Rutherford High Energy Laboratory Chilton Didcot Berkshire
14422873
Neutrino Propulsion for Interstellar Spacecraft
An exotic spacecraft propulsion technology is described which exploits parity violation in weak interactions. Anisotropic neutrino emission from a polarized assembly of weakly interacting particles converts rest mass directly to spacecraft impulse.