878 research outputs found
108, Benedetto Fiandrini, Planimetria e disegni della chiesa abbaziale
No full textLa planimetria e i disegni della chiesa di Polirone sono stati eseguiti da Fiandrini nel 1790 e documentano la condizione dell'abbazi
Search for neutral Higgs boson production through the process e(+)e(-)->Z(*)H(0)
No full textThe results of the searches for neutral Higgs boson production in the process e(+)e(-) --> Z* H-0 are reported, focusing on Higgs boson masses below 70 GeV. The data sample consists of three million hadronic Z(0) decays collected by the L3 experiment at LEP from 1991 through 1994. No signal is found leading to a lower limit on the mass of the Standard Model Higgs boson of 60.2 GeV at 95% C.L. These results are also interpreted in the framework of the General Two Doubler Model and limits on the nonstandard Higgs boson production through the process e(+)e(-) --> Z*h(0) are set. A lower limit of 66.7 GeV at 95% C.L. is obtained for the case where the Higgs decays into an invisible final state
Tests Qed At Lep Energies Using E(+)e(-)-]gamma-gamma(gamma) and E(+)e(-)-]l(+)l(-)gamma-gamma
No full textTotal and differential cross sections for the process e(+)e(-) --> gamma gamma(gamma), and the total cross section for the process e(+)e(-) --> gamma gamma gamma, are measured at energies around 91 GeV using the data collected with the L3 detector from 1991 to 1993. We set lower limits, at 95% CL, on a contact interaction energy scale parameter Lambda > 602 GeV, on the mass of an excited electron m(c)* > 146 GeV and on the QED cut-off parameters Lambda(+) > 149 GeV and Lambda(-) > 143 GeV. Upper limits are also set on the branching fractions of Z decaying into gamma gamma, pi degrees gamma and eta gamma of 5.2 x 10(-5), 5.2 x 10(-5) and 7.6 x 10(-5) respectively. The reactions e(+)e(-) --> rho(+)rho(-)n gamma (rho = e, mu, tau) are studied using the data collected from 1990 to 1994. The data are consistent with the QED expectations
Measurement of the Michel parameters and the average tau neutrino helicity from tau decays in e(+)e(-)->tau(+)tau(-)
No full textThe Michel parameters rho, eta, xi and xi delta, the chirality parameter xi(h) and the tau polarization P-tau are measured using 32012 tau pair decays. Their values are extracted from the energy spectra of leptons and hadrons in tau(-) --> l(-)(l) nu(tau) and tau(-) --> pi(-)nu(tau) decays, the energy and decay angular distributions in tau(-) --> rho(-)nu(tau) decays, and the correlations in the energy spectra and angular distributions of the decay products. Assuming universality in leptonic and semileptonic tau decays, the results are rho = 0.794+/-0.039+/-0.031, eta = 0.25+/-0.17+/-0.11, xi = 0.94+/-0.21+/-0.07, xi delta = 0.81+/-0.14+/-0.06, xi(h) = -0.970+/-0.053+/-0.011, and P-tau = -0.154+/-0.018+/-0.012. The measurement is in agreement with the V-A hypothesis for the weak charged current
Search for neutral B meson decays to two charged leptons
No full textThe decays B-d(0), B-s(0)--> e(+)e(-), mu(+)mu(-), e(+/-)mu(-/+) are LEP I data sample collected by the L3 detector. No signals are observed, therefore upper limits at the 90% (95%) confidence levels are set on the following branching fractions: Br(B-d(0) --> e(+)e(-)) e(+)e(-)) mu(+)mu(-)) mu(+)mu(-)) e(+/-)mu(-/+)) e(+/-)mu(-/+)) e(+)e(-) and B-s(0) --> e(+/-)mu(-/+) are the first limits set on these decay models
Measurement of muon-pair production at 50GeV<root s<86GeV at LEP
No full textUsing the data recorded with the L3 detector at LEP, we study the process e(+)e(-) --> mu(+)mu(-)(gamma) for events with hard initial-slate photon radiation. The effective centre-of-mass energies of the muons range from 50 GeV to 86 GeV. The data sample corresponds to an integrated luminosity of 103.5 pb(-1) and yields 293 muon-pair events with a hard photon along the beam direction. The events are used to determine the cross sections and the forward-backward charge asymmetries at centre-of-mass energies below the Z resonance
Direct detection of high intensity X-ray fluxes with silicon photomultipliers
No full textSilicon Photomultipliers (SiPM) are photodetectors optimized for the detection of infrared to ultraviolet photons and employed in a wide range of fast timing applications for medical imaging and particle detectors. SiPMs are used to detect the passage of ionizing radiation into matter via the collection of secondary photons emitted by the radiator material. In this work, we have investigated the possibility to detect high intensity X-ray fluxes using the DC current produced by SiPMs exposed directly to the X-ray beam, in absence of any passive converter material, to demonstrate the possibility to measure intense radiation fluxes without saturation of the SiPM response. In our application, the signal-to-noise ratio of the SiPM current during the direct exposition to X-rays is typically larger than 100, providing a robust indication of a positive detection. We show that, for a wide range of operational parameters and X-ray flux intensities, the SiPM current can be correlated to the X-ray beam intensity using a parametrization that describes the data with an accuracy of the order or better than 1%. We also show that the SiPM signal current to dark current ratio is maximum for hundreds of mV above the breakdown voltage, with a weak dependence on temperature. These results open the prospects for interesting applications for monitoring intense X-ray beams, for example beam spatial profiling, and possibly real time dosimetry both in medical and industrial applications
Development of a SiPM Cherenkov camera demonstrator for the CTA observatory telescopes
No full textThe Cherenkov Telescope Array (CTA) Consortium is developing the new generation of ground observatories for the detection of ultra-high energy gamma rays. The Italian Institute of Nuclear Physics (INFN) is participating to the R&D of a possible solution for the Cherenkov photon cameras based on Silicon Photomultipliers (SiPM) sensitive to UV energies. INFN is developing the concept, mechanics and electronics for SiPM prototype modules intended to equip the focal planes of CTA telescopes. The module design and performances are reviewed here
Study of the Ks(0)ks(0) Final-state In 2-photon Collisions
No full textThe reaction e(+)e(-) --> e(+)e(-)gamma*gamma* --> e(+)e(-)K(S)(0)K(S)(0) is studied with the L3 detector at LEP and the formation of the f(2)'(1525) resonance is observed, For an integrated luminosity of 114 pb(-1), 31+/-6 f(2)' events are found, Their angular distribution is consistent with a pure helicity two, The radiative width times the branching ratio is measured to be Gamma(gamma gamma)(f(2)')xBr(f(2)'--> K (K) over bar)=(0.093+/-0.018+/-0.022) keV. Only three events are found in the f(2)(1270)-a(2)(1320) mass region, consistent with destructive f(2)-a(2) interference in the (KSKS0)-K-0 final state. The mixing angle of the tensor meson nonet is determined to be theta=(29.4(-1.6)(+1.4))(0)
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