3,838 research outputs found
Baseline LHC machine parameters and configuration of the 2015 proton run
This paper shows the baseline LHC machine parameters for the 2015 start-up.
Many systems have been upgraded during LS1 and in 2015 the LHC will operate at
a higher energy than before and with a tighter filling scheme. Therefore, the
2015 commissioning phase risks to be less smooth than in 2012. The proposed
starting configuration puts the focus on feasibility rather than peak
performance and includes margins for operational uncertainties. Instead, once
beam experience and a better machine knowledge has been obtained, a push in
and performance can be envisaged. In this paper, the focus is on
collimation settings and reach in ---other parameters are covered in
greater depth by other papers in these proceedings.Comment: submitted for publication in a CERN yellow report (Proceedings of the
LHC Performance Workshop - Chamonix 2014
Luminosity Optimization and Calibration in the LHC
The ability of a particle collider to produce the required number of events, the luminosity, is usually used to size its performances. As demonstrated in many accelerators optimizing and calibrating the luminosity can be done using the Van Der Meer method which consist of shifting one beam with respect to the other while recording the event rate. In the LHC it is planned to perform those scans at the four interaction points using the data from the machine detectors as well as the ones from the experiments. A graphical user interface (GUI) has been developed for this purpose. We looked into procedures to quantify and if possible minimize the systematic errors coming from the measurements and the beam parameters and will discuss how we plan on using the relevant informations such as the vertex position or background measurements coming from the experiments
Strong polarization mode coupling in microresonators
We observe strong modal coupling between the TE00 and TM00 modes in Si3N4
ring resonators revealed by avoided crossings of the corresponding resonances.
Such couplings result in significant shifts of the resonance frequencies over a
wide range around the crossing points. This leads to an effective dispersion
that is one order of magnitude larger than the intrinsic dispersion and creates
broad windows of anomalous dispersion. We also observe the changes to frequency
comb spectra generated in Si3N4 microresonators due polarization mode and
higher-order mode crossings and suggest approaches to avoid these effects.
Alternatively, such polarization mode-crossings can be used as a novel tool for
dispersion engineering in microresonators.Comment: Comments are very welcome (send to corresponding author
Article
Phytoplankton production was investigated throughout the whole Benguela ecosystem in winter 1999 and in summer 2002 during two four-week research cruises from Cape Town, South Africa, through Namibian waters to Namibe in southern Angola. Primary production ranged from 0.14â2.26 g C mâ2 dâ1 during JuneâJuly 1999 and from 0.39â8.83 g C mâ2 dâ1 during FebruaryâMarch 2002. Mean productivity values indicated that the Benguela ecosystem was twice as productive in summer than in winter. In 1999, most of the productivity occurred within a temperature range of 13.5â18 °C, whereas in 2002 elevated production was associated with temperatures of 14â22 °C. The relationship between primary production and chlorophyll a was good for winter 1999 but poor for summer 2002, suggesting that predicting primary production from chlorophyll a is not straightforward for the Benguela ecosystem
Hadron Production at Intermediate at RHIC
Large proton and antiproton enhancement with respect to pions has been
observed at intermediate transverse momentum 2-5 GeV/ in Au+Au
collisions at RHIC. To investigate the possible source of this anomaly, the
production of mesons and two particle angular correlations triggered by
mid- baryons or mesons are studied. We also present the first measurement
of proton and antiproton production at GeV in Au+Au
collisions, which aims to study the energy dependence of the observed baryon
enhancement.Comment: 7 pages, 5 figures, proceedings of Hot Quarks 2004 workshop, Taos
Valley, New Mexico, 18-24 Jul 2004,, to be published in J. Phys.
Midface Including Le Fort Level Injuries
Le Fort fractures occur at uniform weak areas in the midface often due to blunt impact to the face. Sporting injuries are a common cause of facial trauma; however, use of protective equipment has reduced the number of sports-related injuries. All patients with traumatic injuries should be evaluated using Advanced Trauma Life Support protocol. Le Fort fractures can contribute to airway obstruction, and urgent intubation may be indicated. Surgery is indicated for most displaced Le Fort fractures to restore function and facial harmony. To facilitate reduction, the original occlusive relationship should be restored by placing the patient in MMF
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