The commissioning of the ATLAS calorimeters with cosmic muons

International audienceThe commissioning of the ATLAS calorimeters is an ongoing process since early 2006. During this period, cosmic muons have been recorded in several runs combining both hadronic and electromagnetic calorimeters. Among the goals are the measuremement of the uniformity of the liquid argon electromagnetic calorimeter to the level of 1% and the intercalibration in time of its channels to 1 ns

Commissioning of ATLAS and early measurements with leptons in ATLAS and CMS

With only a few months until the LHC start-up, the commissioning of ATLAS is in its final stage as the last components of the detector are installed. The understanding of the detector response acquired during the preparation phase is presented as well as the expected performance at start-up. The strategies of both ATLAS and CMS regarding the use of early data involving leptons is then described. Assuming an integrated luminosity of 100\,pb$^{-1}$ in 2008, examples of calibration procedures and early measurements are given

Improved cavity-type absolute total-radiation radiometer

Conical cavity-type absolute radiometer measures the intensity of radiant energy to an accuracy of one to two percent in a vacuum of ten to the minus fifth torr or lower. There is a uniform response over the ultraviolet, visible, and infrared range, and it requires no calibration or comparison with a radiation standard

Conically shaped cavity radiometer with a dual purpose cone winding Patent

Black body radiometer design with temperature sensing and cavity heat source cone windin

Étude du calorimètre électromagnétique d'ATLAS avec des muons cosmiques et du boson de Higgs par sa désintégration en 4 muons

The Large Hadron Collider (LHC) operating since september 2008 will provide proton-proton collisions with a center of mass energy of 14TeV. For experiments like ATLAS, the high luminosity delivered gives the opportunity to search for the Higgs boson and physics beyond the Standard Model. In the first part of this thesis, a study of the electromagnetic calorimeter of ATLAS is performed with cosmic muons. During the commissioning period which began in 2006, the cosmic data were used to measure the performance of this detector and several methods had to be developed in order to analyze them properly. The energy scale and the response uniformity could both be checked to the level of 5%. The second topic of the work is related to the Higgs->ZZ*->4μ channel which is considered as one of the most promising for the Higgs boson discovery. Modications applied to the isolation variables based on the calorimeter and tracker increase the efficiency of the criteria and make them more robust, in particular in the presence of pile-up at high luminosity. An optimal combination of the variables which takes into account the topology of the background events improves the efficiency of the Higgs->ZZ*->4μ signal by 10% and hence increasing the discovery potential of ATLAS

Commissioning of ATLAS and early SM measurements with leptons in ATLAS and CMS

With a few months before the LHC start-up, the commissioning of ATLAS is at its last stage while the last components of the detector are installed. The knowledge acquired during the preparation phase is presented as well as the expected performances at start-up. The strategies of both ATLAS and CMS regarding the use of early data involving leptons is then described. Assuming an integrated luminosity of 100pbâ1 in 2008, examples of calibration procedures and early measurements are given

3D model and accompanying dataset related to the publication: A new, exceptionally preserved juvenile specimen of Eusaurosphargis dalsassoi (Diapsida) and implications for Mesozoic marine diapsid phylogeny

The present contribution contains the 3D model and dataset analyzed in the following publication: Scheyer, T. M., J. M. Neenan, T. Bodogan, H. Furrer, C. Obrist, and M. Plamondon. 2017. A new, exceptionally preserved juvenile specimen of Eusaurosphargis dalsassoi (Diapsida) and implications for Mesozoic marine diapsid phylogeny. Scientific Reports, https://doi.org/10.1038/s41598-017-04514-x

Neuronal Variability during Handwriting: Lognormal Distribution

We examined time-dependent statistical properties of electromyographic (EMG) signals recorded from intrinsic hand muscles during handwriting. Our analysis showed that trial-to-trial neuronal variability of EMG signals is well described by the lognormal distribution clearly distinguished from the Gaussian (normal) distribution. This finding indicates that EMG formation cannot be described by a conventional model where the signal is normally distributed because it is composed by summation of many random sources. We found that the variability of temporal parameters of handwriting - handwriting duration and response time - is also well described by a lognormal distribution. Although, the exact mechanism of lognormal statistics remains an open question, the results obtained should significantly impact experimental research, theoretical modeling and bioengineering applications of motor networks. In particular, our results suggest that accounting for lognormal distribution of EMGs can improve biomimetic systems that strive to reproduce EMG signals in artificial actuators

In situ commissioning of the ATLAS electromagnetic calorimeter with cosmic muons

In 2006, ATLAS entered the {\it in situ} commissioning phase. The primary goal of this phase is to verify the detector operation and performance with cosmic muons. Using a dedicated cosmic muon trigger from the hadronic Tile calorimeter, a sample of approximately $120\,000$ events was collected in several modules of the barrel electromagnetic (EM) calorimeter between August 2006 and March 2007. As cosmic events are generally non-projective and arrive asynchronously with respect to the trigger clock, methods to improve the standard signal reconstruction for this situation are presented. Various selection criteria for projective muons and clustering algorithms have been tested, leading to preliminary results on calorimeter uniformity in $\eta$ and timing performance