10-MICRON Spectral Observations of Moderately Extended Planetary Nebulae
Proc IAU Symp 103
10pm Imaging Polarimetry
Astronomical Society of the Pacific Conference Series, Volume 102
12 渭m imaging polarimetry of the galactic centre.
ASP Conference Series, Volume 14
A search for ttbar resonances in the lepton plus jets final state with ATLAS using 4.7 fb^{-1} of pp collisions at sqrt{s} = 7 TeV
Abstract:
A search for new particles that decay into top quark pairs (ttbar) is performed with the ATLAS experiment at the LHC using an integrated luminosity of 4.7 fb^-1 of proton-proton (pp) collision data collected at a center-of-mass energy sqrt(s)=7 TeV. In the ttbar --> WbWb decay, the lepton plus jets final state is used, where one W boson decays leptonically and the other hadronically. The ttbar system is reconstructed using both small-radius and large-radius jets, the latter being supplemented by a jet substructure analysis. A search for local excesses in the number of data events compared to the Standard Model expectation in the ttbar invariant mass spectrum is performed. No evidence for a ttbar resonance is found and 95% credibility-level limits on the production rate are determined for massive states predicted in two benchmark models. The upper limits on the cross section times branching ratio of a narrow Z' resonance range from 5.1 pb for a boson mass of 0.5 TeV to 0.03 pb for a mass of 3 TeV. A narrow leptophobic topcolor Z' resonance with a mass below 1.74 TeV is excluded. Limits are also derived for a broad color-octet resonance with Gamma/m = 15.3%. A Kaluza-Klein excitation of the gluon in a Randall-Sundrum model is excluded for masses below 2.07 TeV.
Calibration at elevation of the WEAVE fibre positioner
Ground-based and Airborne Instrumentation for Astronomy IX Proc. SPIE 12184 (2022) 121846J
Abstract:
WEAVE is the new wide-field spectroscopy facility for the prime focus of the William Herschel Telescope in La Palma, Spain. Its fibre positioner is essential for the accurate placement of the spectrograph's 960 fibre multiplex. We provide an overview of the recent maintenance, flexure modifications, and calibration measurements conducted at the observatory prior to the final top-end assembly. This work ensures that we have a complete understanding of the positioner's behaviour as it changes orientation during observations. All fibre systems have been inspected and repaired, and the tumbler structure contains new clamps to stiffen both the internal beam and the retractor support disk onto which the field plates attach. We present the updated metrology procedures and results that will be verified on-sky.