Search

The GSO scintillator has a very excellent radiation resistance, fast decay time and large amounts of light yield. Because of these features, GSO will be used to upgrade the current LHCf detector. We examined the features of GSO by using heavy ion beam at Heavy Ion Medical Accelerator in Chiba (HIMAC) Japan. The linearity of PMT R7400 for the large light yield of GSO with a 132Xe beam and the radiation hardness with a 12C beam were measured. As a result, GSO scintillator showed a good linearity up to the signal corresponding to 6 TeV EM-shower maximum in the LHCf detector, and a good radiation hardness up to 7×105 Gy. For the LHCf Arm1 detector, small scaled GSO crystals (GSO bars), have been fabricated for the position determination detector. 5 GSO bars have been manufactured and its performance have been evaluated using 12C beam. Its light yield and position dependency have been evaluated. [ABSTRACT FROM AUTHOR]

The PARIS calorimeter is an apparatus intended for the future SPIRAL2 facility in Caen, France. It will comprise a spherical shell of scintillators detectors making extensive use of LaBr3(Ce) - a relatively new material with excellent energy resolution (∼3% at 662-keV). The individual detector modules will be of a phoswich design where the fast LaBr3(Ce) crystal is optically coupled to a slower conventional crystal like NaI and the scintillation light is collected with a single photomultiplier tube. [ABSTRACT FROM AUTHOR]

Analysis techniques in LHCf are presented, in which all techniques are required to have a high resolution and efficiency in order to overcome the severe situation, small lateral aperture and longitudinally short length of the detector. In this paper, methods for reconstructing an energy of electromagnetic shower are discussed following the data flow of measured data and Monte Carlo simulations. [ABSTRACT FROM AUTHOR]

We discuss some aspects of a new sub-detector for the ALICE experiment at the LHC. This detector would enhance the capabilities of ALICE to study several topics of diffractive as well as of photon induced physics. It consists of four stations of scintillator pads that would tag the diffractive gap more efficiently. [ABSTRACT FROM AUTHOR]

Diffractive and photon induced physics is a research area with a remarkable discovery potential at the LHC. ALICE has started a program to exploit its unique capabilities to study the subject in both proton-proton and heavy ion collisions. We discuss some aspects of a new sub-detector for the ALICE experiment at the LHC. This detector would enhance the performance of ALICE to address some relevant topics on this matter. It consists of four stations of scintillator pads that would tag the diffractive gap more efficiently. [ABSTRACT FROM AUTHOR]

The Simbol-X telescope will be constitued by two satellites in formation flight. One will host the mirror module and the other the detector payload. This payload will be built with two main detectors able to measure the position, energy and arrival time of each focused photon, between 0.5 and 80 keV. The high sensitivity required by Simbol-X will necessitate low noise background detectors. To achieve this goal, those detectors will be surrounded by a passive graded shield, aimed to stop the out of field of view photons, and an active anticoïncidence system to tag the passing particles. This anticoïncidence detector, whose conception, optimisation and realization are under responsibility of the APC Laboratory, Paris, is based on plastic scintillator plates associated to multi-anodes photo-multipliers via optical fibers. In this paper, we will present the present status of the anticoïncidence system and its expected performances. [ABSTRACT FROM AUTHOR]

The LHCf experiment is designed to measure energies and transverse momenta of neutral particles emitted in the forward region of [formula] p-p collision at ±140 m away from the interaction point1 (IP1) of LHC. The energy resolution is confirm to be within 5% and the position resolution is better than 0.2 mm for gamma-rays with energies from 100 GeV to 200 GeV by the test beam results at the CERN-SPS. LHCf has taken data at 2009 and 2010 at s = 900 GeV and 7 TeV collision. A brief summary of LHCf operation at LHC is also reported here. [ABSTRACT FROM AUTHOR]

The Large Hadron Collider forward (LHCf) experiment has performed measurements of the neutral particles emitted to the very forward region of proton-proton collisions at LHC. This experiment is designed to explore very forward interaction at very high energy, which is relevant to interpretation of the data from cosmic-ray experiments. LHCf detector is well optimized to measure photons in the multi-TeV energy range, and to reconstruct neutral pions with two photons. It can also measure neutrons. The data acquisitions at 0.9 TeV and 7 TeV were completed in 2010. In this paper, single photon energy spectra obtained at 0.9 TeV and transverse energy spectra of neutral pions obtained at 7 TeV will be presented. The results are compared with expectations by hadronic interaction models used for air-shower simulations. We found none of these models agree with the obtained data in the photon energy spectra, while EPOS shows a good agreement in the transverse energy spectra of neural pions. Impacts on cosmic-ray and QCD physics are also discussed. [ABSTRACT FROM AUTHOR]

ALICE is one of the four large experiments at the LHC. It focuses on the study of ultra-relativistic heavy ion collisions. Its main goal is to study in great detail the properties of matter under extreme energy densities. We discuss some aspects of the ALICE research program, the experiment future plans as well as some general items of the ALICE upgrade. The present detector allows to study diffractive physics and photon induced processes. A proposal to install detectors in the forward region is presented here. These detectors would allow to study processes with rapidity gaps larger than those presently covered. [ABSTRACT FROM AUTHOR]

The ATLAS detector at CERN's Large Hadron Collider (LHC) will be exposed to proton-proton collisions from beams crossing at 40 MHz. A three-level trigger system was designed to select potentially interesting events and reduce the incoming rate to 100-200 Hz. The first trigger level (LVL1) is implemented in custom-built electronics, the second and third trigger levels are realised in software. The trigger system and its design parameters will be described with focus on computing and data aquision challenges. The results from both commissioning cosmic runs and first experiences from the LHC beam in 2008 will be overviewed. These running periods allowed us to exercise the trigger system online, including its configuration and monitoring infrastructure, as well as reconstruction and selection algorithms. The details on the plans for commissioning the ATLAS trigger when the LHC starts operations will be presented. [ABSTRACT FROM AUTHOR]

An overview of the LHC program is presented, covering the design, construction, first operation and very first results of the collider and experiments. Prospects for the discovery of the Higgs boson, and of physics beyond the standard model are also summarized. [ABSTRACT FROM AUTHOR]

At the end of 2010, the Large Hadron Collider at CERN produced the first Pb-Pb collisions at [formula] TeV. The ALICE Collaboration has measured the multiplicity density of charged particles and its evolution as a function of centrality. In the following, the event and centrality selections, the reconstruction and the analysis method are described. The results are discussed and compared with predictions of different available models. The measurement is also compared to RHIC data ([formula] TeV) and to pp results ([formula] TeV). [ABSTRACT FROM AUTHOR]

The ATLAS detector is capable of resolving the highest energy pp collisions at luminosities sufficient to yield 10' of simultaneous interactions within a bunch collision lasting <0.5 nsec. Already in 2011 a mean occupancy of 20 is often found in pp running. In 2004 studies by ATLAS showed that the detector would have excellent performance also for the foreseeable particle multiplicities in the highest energy p-Pb and Pb-Pb collisions that the LHC will produce. These studies resulted in a letter of intent to the LHC committee by ATLAS to do physics with these beams also. In the past 2 years of data taking, ATLAS detector performance studies have confirmed these expectations at the actual multiplicities presented below. [ABSTRACT FROM AUTHOR]

ALICE (A Large Ion Collider Experiment) is the dedicated heavy-ion experiment at the LHC. In fall 2010, Pb-Pb collisions were recorded at a center-of-mass energy of 2.76 TeV per nucleon pair, about 14 times higher than the energy achieved in A-A collisions at RHIC. The study of the produced hot and dense matter with an unprecedented energy density allows the characterization of the quark-gluon plasma, the deconfined state of quarks and gluons, predicted by QCD. The study of in-medium partonic energy loss allows insights into the density of the medium and the energy-loss mechanisms. This paper presents results based on inclusive spectra as well as two and more-particle correlations of charged particles. These are well suited to assess in-medium effects, ranging from the suppression of particles (RAA) and away-side jets (IAA) at high pT to longrange phenomena attributed to collective effects like the ridge at low pT. The analysis is discussed and the results are presented in the context of earlier RHIC measurements where appropriate. [ABSTRACT FROM AUTHOR]

A Large Ion Collider Experiment (ALICE) is one of the four experiments at the Large Hadron Collider (LHC), and it is dedicated to the study of ultra-relativistic heavy-ion collisions, with the goal of investigating the properties of the high-density state of QCD matter produced in such events. The first Pb-Pb collisions at a centre of mass energy of [formula] TeV per nucleon pair were delivered by LHC in November 2010. In Pb-Pb collisions heavy quarks are regarded as sensitive probes of the interaction dynamics between the parton and the medium produced in such collisions as they are produced on a very short time scale in the initial hard scattering processes and they follow all the evolution of the medium. At the energies available at the LHC charm is produced with large cross section and therefore it is possible to measure its production with good statistical precision. The study of open charm hadrons such as D+, D0, D*+, Ds and Λc in heavy ion collision is of particular interest because it can provide significant insight on the properties of the medium. Proton-proton collision data, that are being recorded at an energy of [formula] TeV since March 2010 provide an essential reference for these studies and allow to test perturbative QCD calculations in an unexplored energy domain. In this paper the analysis of D-meson production, carried out through a study of the hadronic decay channels in Pb-Pb collisions, will be presented in detail. The results for the reconstruction of D0, D+, D*+, and Ds hadrons at central rapidity will be shown along with the first results for the measurement of the D0 and D+ nuclear modification factor and prospects for azimuthal anisotropy studies. [ABSTRACT FROM AUTHOR]

We give a brief description of the purpose of the LHCf experiment, detectors and their performance, and what has been done in the first year experiment. A short summary of results at [formula] is given although the energy is not an 'intrinsic' LHC energy. Since detailed results at [formula] will appear soon elsewhere, here we limit ourselves to giving also a brief account of what will come in that paper. [ABSTRACT FROM AUTHOR]

The observation of diffraction at LHC with the CMS detector at [formula] and 2360 GeV is presented, along with a comparison of the data with the predictions of the PYTHIA and PHOJET generators. [ABSTRACT FROM AUTHOR]

The first measurements of charged particle production in proton-proton collisions at center-of-mass energy [formula] and 7 TeV recorded with the ATLAS detector at the LHC are presented. Minimum bias distributions are measured for events with at least one charged particle in the kinematic range |η| <2.5 and pT>500 MeV and compared with the predictions from various Monte Carlo models. Activity in the underlying event was measured with respect to the highest pT track in the event. Both the minimum bias and underlying event measurements are fully corrected for detector effects to obtain distributions at the hadron level. A new PYTHIA6 Monte Carlo tune, ATLAS Minimum Bias Tune 1, was produced using ATLAS minimum bias distributions measured in a diffractive limited phase-space in combination with measurements from previous hadron collider experiments. The new tune is shown to significantly improve the predictions for minimum bias distributions measured in the diffractive limited phase-space. [ABSTRACT FROM AUTHOR]

Presented are the results of the most recent studies by the CMS and ATLAS collaborations on the expected sensitivity of their detectors to observing a Higgs boson at LHC. The overview is preceded with a brief summary of the LHC and the CMS Experiment status. [ABSTRACT FROM AUTHOR]