Simulation of a Cross Section and Mass Measurement of a SM Higgs Boson in the H->WW->lvlv Channel at the LHC

The potential to discover a Standard-Model-like Higgs boson at the LHC in the mass range from 150-180 GeV, decaying into a pair of W bosons with subsequent leptonic decays, has been established during the last 10 years. Assuming that such a signal will eventually be observed, the analysis described in this paper investigates how accurate the signal cross section can be measured and how the observable lepton pt spectra can be used to constrain the mass of the Higgs boson. Combining the signal cross section with the analysis of the lepton pt spectra and assuming the SM Higgs cross section is known with an accuracy of +-5%, our study indicates that an integrated luminosity of about 10 fb-1 allows to measure the mass of a SM Higgs boson with an accuracy between 2 and 2.5 GeV.Comment: 19 pages, 11 Figure

Comparison between high-energy proton and charged pion induced damage in Lead Tungstate calorimeter crystals

A Lead Tungstate crystal produced for the electromagnetic calorimeter of the CMS experiment at the LHC was cut into three equal-length sections. The central one was irradiated with 290 MeV/c positive pions up to a fluence of (5.67 +- 0.46)x10^13 /cm^2, while the other two were exposed to a 24 GeV/c proton fluence of (1.17 +- 0.11) x 10^13/ cm^2. The damage recovery in these crystals, stored in the dark at room temperature, has been followed over two years. The comparison of the radiation-induced changes in light transmission for these crystals shows that damage is proportional to the star densities produced by the irradiation.Comment: 7 pages, 4 figure

A visualization of the damage in Lead Tungstate calorimeter crystals after exposure to high-energy hadrons

The anticipated performance of calorimeter crystals in the environment expected after the planned High-Luminosity upgrade of the Large Hadron Collider (HL-LHC) at CERN has to be well understood, before informed decisions can be made on the need for detector upgrades. Throughout the years of running at the HL-LHC, the detectors will be exposed to considerable fluences of fast hadrons, that have been shown to cause cumulative transparency losses in Lead Tungstate scintillating crystals. In this study, we present direct evidence of the main underlying damage mechanism. Results are shown from a test that yields a direct insight into the nature of the hadron-specific damage in Lead Tungstate calorimeter crystals exposed to 24 GeV/c protons.Comment: 8 pages, 6 figure

Performance studies of scintillating ceramic samples exposed to ionizing radiation

Scintillating ceramics are a promising, new development for various applications in science and industry. Their application in calorimetry for particle physics experiments is expected to involve an exposure to high levels of ionizing radiation. In this paper, changes in performance have been measured for scintillating ceramic samples of different composition after exposure to penetrating ionizing radiation up to a dose of 38 kGy.Comment: 6 pages, 8 figures, to be published in the 2012 IEEE Nuclear Science Symposium Conference Recor

Detection of Cherenkov light from air showers with Geiger-APDs

We have detected Cherenkov light from air showers with Geiger-mode APDs (G-APDs). G-APDs are novel semiconductor photon-detectors, which offer several advantages compared to conventional photomultiplier tubes in the field of ground-based gamma-ray astronomy. In a field test with the MAGIC telescope we have tested the efficiency of a G-APD / light catcher setup to detect Cherenkov light from air showers. We estimate a detection efficiency, which is 60% higher than the efficiency of a MAGIC camera pixel. Ambient temperature dark count rates of the tested G-APDs are below the rates of the night sky light background. According to these recent tests G-APDs promise a major progress in ground-based gamma-ray astronomy.Comment: 4 pages, 5 figures, to appear in the proceedings of the 30th International Cosmic Ray Conference, Merida, July 200

Production of Kaluza-Klein States at Future Colliders

Perturbative breaking of supersymmetry in four-dimensional string theories predict in general the existence of new large dimensions at the TeV scale. Such large dimensions lie in a domain of energies accessible to particle accelerators. Their main signature is the production of Kaluza-Klein excitations which can be detected at future colliders. We study this possibility for hadron colliders (TEVATRON, LHC) and $e^+ e^-$ colliders (LEP-200, NLC-500).Comment: 13 pages, LATEX, 4 postscript figures appended at the end, CPTH-A293.0294 and IEM-FT-84/9

Towards a Precise Parton Luminosity Determination at the CERN LHC

A new approach to determine the LHC luminosity is investigated. Instead of employing the proton-proton luminosity measurement, we suggest to measure directly the parton-parton luminosity. It is shown that the electron and muon pseudorapidity distributions, originating from the decay of W+, W- and Z0 bosons produced at 14 TeV pp collisions (LHC), constrain the x distributions of sea and valence quarks and antiquarks in the range from about 3 x 10**-4 to about 10**-1 at a Q**2 of about 10**4 GeV**2. Furthermore, it is demonstrated that, once the quark and antiquark structure functions are constrained from the W+,W- and Z0 production dynamics, other quark-antiquark related scattering processes at the LHC like q-qbar --> W+W- can be predicted accurately. Thus, the lepton pseudorapidity distributions provide the key to a precise parton luminosity monitor at the LHC, with accuracies of about +-1% compared to the so far considered goal of +-5%.Comment: plain tex, 14 pages, 5 figure

High-energy proton induced damage study of scintillation light output from PbWO4 calorimeter crystals

Eight PbWO4 crystals produced for the electromagnetic calorimeter of the CMS experiment at LHC have been irradiated in a 20 GeV/c proton beam up to fluences of 5.4 E13 p/cm2. The damage recovery in these crystals, stored in the dark at room temperature, has been followed for over a year. Comparative irradiations with 60Co photons have been performed on seven other crystals using a dose rate of 1 kGy/h. The issue whether hadrons cause a specific damage to the scintillation mechanism has been studied through light output measurements on the irradiated crystals using cosmic rays. The correlation between light output changes and light transmission changes is measured to be the same for proton-irradiated crystals and for gamma-irradiated crystals. Thus, within the precision of the measurements and for the explored range of proton fluences, no additional, hadron-specific damage to the scintillation mechanism is observed.Comment: 7 pages, 4 figure