EPJ Web of Conferences | Year: 2012
The identification of b jets is a crucial issue to study and characterize various channels like top quark events and many new physics scenarios. Different b-tagging techniques are defined in CMS which benefit from the long life time, high mass and large momentum fraction of the b-hadron produced in b-quark jet. Efficient algorithms have been developed based on the measure of b-hadron secondary vertex or on tracks with a large impact parameter. Data collected in pp collisions at √s=7TeV in 2011 are used to estimate both the b-tagging efficiency and the mistag rate from light flavor jets. © Owned by the authors 2012.
Bisch C.,CEA Saclay Nuclear Research Center |
Mougeot X.,CEA Saclay Nuclear Research Center |
Be M.-M.,CEA Saclay Nuclear Research Center |
Nuclear Data Sheets | Year: 2014
A system for the measurement of beta energy spectra has been developed. It is based on a silicon semi-conductor detector operating at liquid nitrogen temperatures, under ultra high-vacuum. Monte-Carlo simulations were made to optimize the detection chamber and the source holder. Descriptions of the electronic and mechanical systems are included, as well as the first measured spectra. © 2014 Elsevier Inc.
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2010
Main achievements of more than one decade of CMOS pixel sensor R&D for charged particle tracking are reviewed in this paper, together with the goals driving present R&D activities, i.e. read-out speed and radiation tolerance. A fast read-out sensor developed for the EUDET beam telescope and the STAR vertex detector is described as well as its first test results. Preliminary results are also provided on non-ionising radiation tolerance improvements offered by CMOS processes featuring a depleted epitaxial layer. Finally, the recent access to 3D Integration Technologies, which alleviate most essential CMOS sensor's limitations, has translated into 2- and 3-tier sensor designs, to be fabricated in Spring 2009. Their main design features and expected performances are reviewed. © 2010 Elsevier B.V. All rights reserved.
Nerlo-Pomorska B.,Maria Curie Sklodowska University |
Pomorski K.,Maria Curie Sklodowska University |
Schmitt C.,French Atomic Energy Commission |
Physica Scripta | Year: 2014
The evolution of fragment mass distribution in low-energy fission is studied as a function of the composition of the fissioning system over a wide range, from Hg to Fm isotopes. The relative importance of symmetric and asymmetric fission modes is investigated within a static picture based on elaborate, four-dimensional potential energy spaces using the modified Funny-Hills deformation coordinates. The potential energy is computed with the macroscopic-microscopic method. The Lublin-Strasbourg drop model is used to calculate the macroscopic part of the potential energy, while the Yukawa folded single-particle potential with an improved Strutinsky method and the Bardeen-Cooper-Schrieffer theory are employed to evaluate the shell and pairing contributions to the macroscopic energy. From the analysis of the potential energy surfaces, equilibrium deformations and saddle-point shapes are determined. A coexistence of symmetric and asymmetric fission valleys is observed. The relative depth of these valleys depends on the fissioning nucleus. The valleys' competition is used to explain the evolution of the fission-fragment mass distribution, from asymmetric fission in 180Hg to symmetric fission in 260Fm. Good qualitative agreement is found with the experiment. © 2014 The Royal Swedish Academy of Sciences.
Jangal S.,IPHC |
Jangal S.,Ecole des Mines de Nantes
Journal of Physics: Conference Series | Year: 2011
The ALICE collaboration is interested in measuring the ξ =ln(p jet T/p hadron T) distribution of hadrons in jets known as the Hump-backed plateau (HBP). After an introduction to color coherence effects responsible for the shape of the HBP, we discuss the ALICE capabilities to perform such a study. Preliminary results from ALICE for non corrected charged particle and jet spectra measurement in p+p collisions at √s = 900 GeV and 7 TeV are presented. Finally, we show the results of a MC based analysis of intrajet radiations. It supports the idea of jet collimation which increases with increasing jet energy as expected from QCD and show the feasability of this study with ALICE. © Published under licence by IOP Publishing Ltd.