259 research outputs found
The First 1 1/2 Years of TOTEM Roman Pot Operation at LHC
Since the LHC running season 2010, the TOTEM Roman Pots (RPs) are fully
operational and serve for collecting elastic and diffractive proton-proton
scattering data. Like for other moveable devices approaching the high intensity
LHC beams, a reliable and precise control of the RP position is critical to
machine protection. After a review of the RP movement control and position
interlock system, the crucial task of alignment will be discussed.Comment: 3 pages, 6 figures; 2nd International Particle Accelerator Conference
(IPAC 2011), San Sebastian, Spain; contribution MOPO01
Dimethylcethrene: A Chiroptical Diradicaloid Photoswitch
We describe the synthesis and properties of 13,14-dimethylcethrene, a prototype of a chiral diradicaloid photochemical switch that can be transformed reversibly via conrotatory electrocyclization to its more stable closed form by light (630 nm) or heat and back to its open form by light (365 nm). This system illustrates how the chemical reactivity of a diradicaloid molecule can be translated into a switching function, which alters substantially all electronic parameters, namely, the HOMOâLUMO and the singletâtriplet (ST) energy gaps, and the degree of helical twist. As a result, distinct changes in the optical and chiroptical properties of this system were observed, which allowed us to monitor the switching process by a variety of spectroscopic techniques, including NMR, UVâvis, and CD. In comparison to the previously reported parent molecule cethrene, this system benefits from two methyl substituents installed in the fjord region, which account for the stability of the closed form against oxidation and racemization. The methyl substituents increase the ST energy gap of 13,14-dimethylcethrene by âź4 kcal molâ1 in comparison to cethrene. Our DFT calculations reveal that the larger ST gap is a result of electronic and geometric effects of the methyl substituents and show the potential of related systems to act as magnetic switches at room temperature
ArDM: first results from underground commissioning
The Argon Dark Matter experiment is a ton-scale double phase argon Time
Projection Chamber designed for direct Dark Matter searches. It combines the
detection of scintillation light together with the ionisation charge in order
to discriminate the background (electron recoils) from the WIMP signals
(nuclear recoils). After a successful operation on surface at CERN, the
detector was recently installed in the underground Laboratorio Subterr\'aneo de
Canfranc, and the commissioning phase is ongoing. We describe the status of the
installation and present first results from data collected underground with the
detector filled with gas argon at room temperature.Comment: 6 pages, 3 figures, Light Detection In Noble Elements (LIDINE 2013
Status of the ArDM Experiment: First results from gaseous argon operation in deep underground environment
The Argon Dark Matter (ArDM-1t) experiment is a ton-scale liquid argon (LAr)
double-phase time projection chamber designed for direct Dark Matter searches.
Such a device allows to explore the low energy frontier in LAr. After
successful operation on surface at CERN, the detector has been deployed
underground and is presently commissioned at the Canfranc Underground
Laboratory (LSC). In this paper, we describe the status of the installation and
present first results on data collected in gas phase.Comment: 21 pages, 20 figure
Les Houches "Physics at TeV Colliders 2003" Beyond the Standard Model Working Group: Summary Report
The work contained herein constitutes a report of the ``Beyond the Standard
Model'' working group for the Workshop "Physics at TeV Colliders", Les Houches,
France, 26 May--6 June, 2003. The research presented is original, and was
performed specifically for the workshop. Tools for calculations in the minimal
supersymmetric standard model are presented, including a comparison of the dark
matter relic density predicted by public codes. Reconstruction of
supersymmetric particle masses at the LHC and a future linear collider facility
is examined. Less orthodox supersymmetric signals such as non-pointing photons
and R-parity violating signals are studied. Features of extra dimensional
models are examined next, including measurement strategies for radions and
Higgs', as well as the virtual effects of Kaluza Klein modes of gluons. An LHC
search strategy for a heavy top found in many little Higgs model is presented
and finally, there is an update on LHC studies.Comment: 113 pages, ed B.C. Allanach, v5 has changes to part XV
Performance of the CMS Cathode Strip Chambers with Cosmic Rays
The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device
in the CMS endcaps. Their performance has been evaluated using data taken
during a cosmic ray run in fall 2008. Measured noise levels are low, with the
number of noisy channels well below 1%. Coordinate resolution was measured for
all types of chambers, and fall in the range 47 microns to 243 microns. The
efficiencies for local charged track triggers, for hit and for segments
reconstruction were measured, and are above 99%. The timing resolution per
layer is approximately 5 ns
Performance and Operation of the CMS Electromagnetic Calorimeter
The operation and general performance of the CMS electromagnetic calorimeter
using cosmic-ray muons are described. These muons were recorded after the
closure of the CMS detector in late 2008. The calorimeter is made of lead
tungstate crystals and the overall status of the 75848 channels corresponding
to the barrel and endcap detectors is reported. The stability of crucial
operational parameters, such as high voltage, temperature and electronic noise,
is summarised and the performance of the light monitoring system is presented
Crustal analysis of maud rise from combined satellite and near-surface magnetic survey data
The Higgs Working Group: Summary Report 2003
Theoretical progress in Higgs boson production and background processes is
discussed with particular emphasis on QCD corrections at and beyond
next-to-leading order as well as next-to-leading order electroweak corrections.
The residual theoretical uncertainties of the investigated processes are
estimated in detail. Moreover, recent investigations of the MSSM Higgs sector
and other extensions of the SM Higgs sector are presented. The potential of the
LHC and a high-energy linear e+e- collider for the measurement of Higgs
couplings is analyzed.Comment: 169 pages, Proceedings 3rd Les Houches Workshop: Physics at TeV
Colliders, Les Houches, France, 26 May - 6 Jun 200
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