136882880
Effect of radiation on the mechanical properties of polyethylene terephthalate films
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.
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.
54530109
8 GEV BEAM LINE OPTICS OPTIMIZATION FOR THE RAPID ANTIPROTON TRANSFERS AT FERMILAB
Tevatron Run-II upgrade requires a significant increase of the efficiency and speed of the antiproton transfers from the Accumulator to the Recycler. The goal for the total transfer time is challenging a reduction from 1 hour down to a few minutes. Here we discuss the beam line optics aspects of this project. Results of lattice measurements and optimization are analyzed in terms of transport efficiency and stability.
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
54052136
Progress in Antiproton Production at the Fermilab Tevatron Collider
Fermilab Collider Run II has been ongoing since 2001. During this time peak luminosities in the Tevatron have increased from approximately 10 x 10{sup 30} cm{sup -2}sec{sup -1} to 300 x 10{sup 30} cm{sup 02}sec{sup -1}. A major contributing factor in this remarkable performance is a greatly improved antiproton production capability. Since the beginning of Run II, the average antiproton accumulation rate has increased from 2 x 10{sup 10}{anti p}/hr to about 24 x 10{sup 10}{anti p}/hr. Peak antiproton stacking rates presently exceed 28 x 10{sup 10}{anti p}/hr. The antiproton stacking rate has nearly doubled since 2005. It is this recent progress that is the focus of this paper. The process of transferring antiprotons to the Recycler Ring for subsequent transfer to the collider has been significantly restructured and streamlined, yielding additional cycle time for antiproton production. Improvements to the target station have greatly increased the antiproton yield from the production target. The performance of the Antiproton Source stochastic cooling systems has been enhanced by upgrades to the cooling electronics, accelerator lattice optimization, and improved operating procedures. In this paper, we will briefly report on each of these modifications.
118522497
Visual Observability of the Cassiopeia A Supernova
It is generally believed that the explosion which gave birth to the Cassiopeia A supernova remmant resulted from core collapse of a hydrogen-deficient star. A progenitor that has lost all its hydrogen envelope and part of its helium envelope would lead to an explosion with the optical properties of a Type Ic supernova. There is evidence, if not general agreement, that Flamsteed observed the Cas A supernova as a sixth magnitude object in August, 1680. If an explosion with a typical SNIc light curve at the position and distance of Cas A attained maximum luminosity during the winter of 1679-1680, it would at that time have been poorly situated for visual observation, as its upper culmination would have taken place during daylight, while in August, between 170-200 days after peak luminosity, it would have been a sixth magnitude star.