Luciano Barone

High energy cosmic muons and the calibration of the L3 electromagnetic calorimeter

Abstract A method to calibrate the L3 electromagnetic calorimeter with cosmic muons has been tested on a matrix of 100 tapered BGO crystals. Calibration constants in the energy range of 20–30 MeV were measured at the 2% level collecting about 200 muons per crystal. The results are in agreement with the calibration constant determined using a 10 GeV electron beam.

Ordinary and extraordinary complex refractive index of the lead tungstate (PbWO4) crystal

Abstract The ordinary and the extraordinary complex refractive index of PbWO 4 together with the crystal optical axis orientation are determined on the basis of transmittance and reflectance measurements at normal incidence with polarised light and the measurement of the separation angle between the ordinary and the extraordinary ray at various laser wavelengths. The real part of the extraordinary complex refractive index is lower than the ordinary one (i.e. PbWO 4 is a negative uniaxial crystal) and they seem not to be affected by a 30 ppm Nb 5+ doping.

Precise determination of the light yield of scintillating crystals

Abstract A method to determine the photopeak position of the γ absorption spectrum of radioactive sources in low light yield scintillators as lead tungstate is discussed. The method is based on the parametrization of both the Compton and photoelectric contributions to the spectrum and it is proven to be reliable and to give stable and precise results.

Parametrization of Proton Structure Functions

Abstract We present a parametrization of the parton densities as derived from the data collected by the CHARM Collaboration in the wide band beam neutrino and antineutrino weak charged-current interactions. They are rescaled to the proton and calculated at a reference Q 2 value of 10 GeV 2 including the next-to-leading order corrections and imposing the Gross-Llewellyn Smith and the momentum sum rules.

Experimental verification of the universality of electron-neutrino and muon-neutrino coupling to the neutral weak current

Abstract The ratio of the coupling strengths of electron- and muon-neutrinos to the neutral weak current, derived from measurements of total semileptonic neutrino cross sections on an isoscalar target, is reported on. Using an enriched electron-neutrino beam with equal fluxes of ν e and ν e produced by dumping the 400 GeV on beam of the CERN-SPS into thick copper targets (beam-dump), σ( NC ( (−) ν e ))/σ( CC ( (−) ν e )) = 0.406 −0.135 +0.145 is measured. Combining this value with the re we obtained in an exposure to a narrow band neutrino beam, the ratio of the coupling constants g ν e ν e /g ν μ v μ = =1.05 −0.18 +0.15 is derived, in good agreement with universal coupling strength of the electron- and muon-neutrino to the neutral weak current.

Study of the energy calibration of a high resolution electromagnetic calorimeter

Abstract A calibration study was performed on a prototype of the L3 BGO electromagnetic calorimeter. The accuracy and stability reached is a small fraction of the typical detector resolution.

Calibration of the Charm Fine Grained Calorimeter

Abstract Calorimeters have been used extensively for the study of neutrino interactions in the last decade. This paper describes the need for calibration of such calorimeters and how this was realized for the case of the CHARM fine-grained calorimeter. The energy and spatial response of the calorimeter to both hadronic and electromagnetic showers was measured in π and electron beams from 5 to 140 GeV. The results and resolutions are presented.

Study of a BGO calorimeter using electron and hadron beams from 1 to 50 GeV

Abstract A calorimeter of 25 bismuth germanate (BGO) crystals equipped with silicon photodiode readout has been tested at the CERN SPS in the energy range 1–50 GeV. The response for electrons has been shown to be linear in this energy range and the rms resolution obtained ( σ E E ) is approximately 1%, for E > 4 GeV. The electron/pion separation was found to be better than 1:500 in the energy range 1–20 GeV. Data on lateral and longitudinal shower development were compared with the results of a Monte Carlo simulation using the SLAC-EGS program and found to be in good agreement.

A detector for submillimeter gamma cameras

Anger cameras (SPECT etc.) presently used in nuclear medicine employ as active detector NaI crystals, obtaining intrinsic spatial resolutions ≥ 3mm. Arrays made of optically isolated single crystal elements of YAP:Ce, having sub-millimeter aperture size, read out by position sensitive photomultipliers, allow to build active detectors to employ in SPECT systems, with intrinsic spatial resolution below the millimeter, and with time resolution of the order of tens of nanoseconds. In this paper preliminary results of measurements carried on different kinds of YAP:Ce arrays are reported. The measurements have been performed aiming to optimize the geometrical and physical parameters of the crystals in order to accomplish a SPEM (Single Photon Emission Mammography) camera detector.

Ionization loss in BGO

Abstract We report on a precise measurement of the energy loss through ionization by pions in bismuth germanate performed at several values of the incident particles momentum with a prototype of the L3 electromagnetic calorimeter. The experimental results are in good agreement with theoretical predictions showing the relativistic rise modified by density effect.