Lead Glass Cherenkov Counter Research Articles

Measurement of structure dependent radiative K+ → e+νγ decay at J-PARC

The J-PARC E36 experiment is aiming at searching for lepton universality violation by accurately measuring the ratio of branching ratio of the K + → e + ν(γ) (K e2(γ)) to K + → μ + ν(γ) (K μ2(γ)) decays. The experiment was performed at J-PARC employing a stopped K + method in conjunction with a 12-sector iron-core superconducting toroidal spectrometer. Charged particle momenta were determined by reconstructing charged particle trajectories in the spectrometer. Particle identification for e + and μ + was carried out using an aerogel Cherenkov counter and a lead-glass Cherenkov counter, as well as by measuring the time-of-flight between TOF counters. The peak structure due to K e2(γ) decay was successfully observed in the e + momentum spectrum after the e + requirement in the PID analysis. The structure dependentradiative K + → e + νγ () events were selected by imposing photon hits in the CsI(Tl) calorimeter or the GSC counter. The experimental spectra were accurately reproduced by the Monte Carlo simulation, indicating a correct understanding of the experimental conditions. The Br() value relative to Br(K e2(γ)) was determined from the and K e2(γ) yields corrected for the detector acceptances. The Br()/Br(K e2(γ)) ratio was derived to be 1.19 ± 0.07 stat ± 0.04 syst in the CsI(Tl) analysis and 1.25 ± 0.14 stat ± 0.04 syst in the GSC analysis.

The FOREST detector for meson photoproduction experiments at ELPH

An electromagnetic calorimeter complex, FOREST, has been constructed for meson photoproduction experiments at the Research Center for Electron Photon Science, Tohoku University. It consists of three types of calorimeters, which are made of pure cesium-iodide crystals, lead scintillating-fiber modules, and lead glass Cherenkov counters. Each calorimeter is equipped with a plastic scintillator hodoscope to identify charged particles. The design and performance of FOREST are described. The energy responses of test calorimeters have been investigated by using 100–800MeV positron beams. The energy resolutions of the three calorimeters are found to be approximately 3%, 7%, and 5% for 1-GeV photons, respectively. A cryogenic hydrogen/deuterium target system fitted to the FOREST experiments and a newly developed data acquisition system are also presented.

Performance test of a lead-glass counter for the J-PARC E36 experiment

The J-PARC E36 experiment will search for a violation of lepton universality by a precise measurement of the ratio of the kaon decay widths RK=Γ(K+→e+ν)/Γ(K+→μ+ν). Charged particles will be identified by the combination of three independent systems: a lead-glass Cherenkov counter, an aerogel Cherenkov counter, and a time-of-flight measurement. The performance of the lead-glass Cherenkov counter was investigated with e+, μ+, and π+ beams in the relevant momentum region from the K+ decays. By using a polyethylene degrader to slow down the beam momentum in front of the lead-glass block, we succeeded in reducing the muon mis-identification probability down to 5% while maintaining a high e+ detection efficiency of 98%.

Electromagnetic calorimeter for the HADES@FAIR experiment

An electromagnetic calorimeter (ECAL) is being developed to complement the dilepton spectrometer HADES currently operating on the beam of the SIS18 heavy-ion synchrotron at GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany. The ECAL will allow the HADES@FAIR experiment to measure data on neutral meson production in heavy ion collisions in the energy range of 2–10 AGeV with the beam of the future accelerator SIS100@FAIR. The calorimeter will also improve the electron-hadron separation of the spectrometer, and will be used for the detection of photons from strange resonances in elementary and heavy ion reactions as well. The calorimeter will consist of 978 modules divided into 6 sectors, and it will cover forward angles of 16° < Θ < 45° and almost full azimuthal angle. Each module consists of a lead glass Cherenkov counter, photomultiplier, HV divider and an optical fiber. A dedicated LED based system being developed to monitor the stability of the calorimeter is discussed. Various prototypes of front-end electronics are presented and the achieved energy and time resolution determined using pulses from a pulse generator and a real detector signal induced by LED pulses and cosmic muons is shown as well.

EM CALORIMETER COMPLEX FOREST FOR THE π0 AND η PHOTO-PRODUCTION EXPERIMENTS AT LNS-SENDAI

A large solid angle γ-ray detector system, FOREST, has been constructed at LNS-Sendai to study the π0 and η photo-production reactions. The FOREST detector consists of three electro-magnetic calorimeters: pure CsI crystals, Lead/SciFi blocks and Lead Glass Cherenkov counters. It covers about 90% of the total solid angle. A new data acquisition system for the FOREST detector has been developed to handle high rate trigger events with a high efficiency. To investigate performances of FOREST and the DAQ system, a test experiment has been conducted. The π0 and η mesons are clearly observed. A DAQ efficiency of 76% has been obtained at a 2 kHz trigger request.

The CHAOS spectrometer for pion physics at TRIUMF

The Canadian high acceptance orbit spectrometer (CHAOS) is a unique magnetic spectrometer system recently commissioned for studies of pion induced reactions at TRIUMF. It is based on a cylindrical dipole magnet producing vertical magnetic fields up to 1.6 T. The scattering target is located in the center of the magnet. Charged particle tracks produced by pion interactions there are identified using four concentric cylindrical wire chambers surrounding the target. Particle identification and track multiplicity are determined by cylindrical layers of scintillation counters and lead-glass Cherenkov counters, which also provide a first level trigger. A sophisticated second level trigger system permits pion fluxes in excess of 5 MHz to be employed. The detector subtends 360° in the horizontal plane, and ±7° out of this plane for a solid angle coverage approximately 10% of 4π sr. The momentum resolution delivered by the detector system is 1% (σ).

The electromagnetic calorimeter in the hyperon beam experiment at CERN

An electromagnetic calorimeter has been built for the hyperon beam experiment WA89 at CERN. It is composed of 642 lead glass Cherenkov counters. The detector was calibrated with an electron test beam and with an extensive π0 sample produced in hyperon beam runs. The setup, the performance and results from operation in WA89 are presented.

A Method of π0 Energy Reconstruction

We present a method of π0 energy reconstruction by measuring two decay photon energies from a π0 meson and their opening angle. Although most high-energy photon detectors display an energy dependence on the energy resolution (FWHM) which is proportional to 1/√E, the resolution is poor for low-energy photons, this method improves there constructed π0 energy resolution. The method gives a simple analytic formula by taking into account the energy dependence of the photon-energy resolution of detectors such as lead-glass Cherenkov counters. It is verified by a Monte Carlo calculation that the method is more accurate and more reliable than other methods. The method is applicable to a particle which decays into two photons, such as an η meson.

Thallium formate heavy liquid counter “Helicon” as a total absorption calorimeter

Abstract The results of tests using a thallium formate Tl(HCO2) heavy liquid counter “HELICON” as a total absorption calorimeter are reported. The results indicate that the thallium formate HELICON can be used with characteristics equivalent or even superior to those of an SF-5 lead glass Cherenkov counter. In particular it possesses a high resistance to radiation damage.

A large lead glass Cherenkov counter hodoscope

We report on the construction, calibration, and performance of a 194-element lead glass Cherenkov counter array. The array which covered an area of 1.2 m × 3.0 m measured photon and electron energies in a K L 0 decay experiment at the Brookhaven AGS.

Electron-Induced Cascade Shower in Lead Glass

In order to provide useful data for designing a lead glass Cherenkov counter, observations were made on the longitudinal distributions of cascade showers developed in the SF-2 lead glass at the energies of 450, 650 and 800 MeV. The results agreed well with the calculated values based on the approximation B.

A streamer-chamber detector at the CERN intersecting storage rings

The design, construction, and performance of a streamer-chamber system for the study of inelastic proton-proton collisions at the CERN ISR are described. The chambers have specially shaped ground electrodes to accomodate the ISR vacuum chamber and to obtain an almost 4π solid angle. Problems arising from the non-flat electrodes and the insertion of converter plates into the sensitive volume of the chambers are discussed. The high-voltage and gas system are described and in particular the control system for the streamer-chamber memory time which is essential for operation at high ISR luminosities. The optical system, including single-stage electrostatic image intensifiers, is explained. The chambers are tiggered on inelastic beam-beam interactions with counter hodoscopes, or on interactions including a photon which is detected in a lead-glass Cherenkov counter located at 90°. Finally the analysis of the pictures is described.

Detection of 10- to 100-MeV photons with lead-glass cherenkov counters

We describe the use of a 10 × 10 × 15cm 3 lead-glass Cherenkov counter as a detector of photons with energies as low as 10 MeV. A procedure for calibrating the efficiency of the counter without the use of tagged photons is presented. Using electron-beam measurements and a Monte Carlo calculation, we find that a normally-incident photon is detected with an efficiency of 62% at 15 MeV and 87% at 25 MeV.

Charge-Exchange Scattering of Negative Pions at 150 Mev

The charge-exchange scattering of pi /sup -/ by hydrogen was measured at a bombarding energy of 150 Mev. The energy distribution of gamma rays from the decay of pi /sup 0/ was measured with a lead glass Cherenkov counter at laboratory angles of 45, 75, 105, and 135 deg . If the charge exchange differential scattering cross section in the center-of-mass system is expanded as a series of Legendre polynomials, the result is: d sigma /d OMEGA = (1.00 plus or minus 0.03)STA3.39 plus or minus 0.11 -- (1.54 plus or minus 0.29)P/sub 1/ (cos theta ') + (3.57 plus or minus 0.56)P/sub 2/(cos theta ')!mb-sr/sub -1/. The tot al cross section for charge exchange, obtained by integration, is then sigma /sub tot/( pi /sup -/ yields pi /sup 0/) = 42.6 plus or minus 1.9 mb. (auth)

Charge-Exchange Scattering of Negative Pions at 61 Mev and 95 Mev

The charge-exchange scattering of negative pions by liquid hydrogen has been measured at 61\ifmmode\pm\else\textpm\fi{}1 Mev and 95\ifmmode\pm\else\textpm\fi{}2 Mev bombarding energy. The measurements were made with a gamma-ray spectrometer which employs a lead glass \ifmmode \check{C}\else \v{C}\fi{}erenkov counter. If the charge exchange scattering cross section is expanded as a series of Legendre polynomials in the center-of-mass system of the collision, we find that at 61 Mev, $\frac{d\ensuremath{\sigma}}{d\ensuremath{\Omega}}=(1.00\ifmmode\pm\else\textpm\fi{}0.05)[0.613\ifmmode\pm\else\textpm\fi{}0.030\ensuremath{-}(0.830\ifmmode\pm\else\textpm\fi{}0.068){P}_{1}({cos\ensuremath{\theta}}^{\ensuremath{'}})+(0.183\ifmmode\pm\else\textpm\fi{}0.150){P}_{2}({cos\ensuremath{\theta}}^{\ensuremath{'}})],$ and at 95 Mev, $\frac{d\ensuremath{\sigma}}{d\ensuremath{\Omega}}=(1.00\ifmmode\pm\else\textpm\fi{}0.03)[1.05\ifmmode\pm\else\textpm\fi{}0.05\ensuremath{-}(1.15\ifmmode\pm\else\textpm\fi{}0.12){P}_{1}({cos\ensuremath{\theta}}^{\ensuremath{'}})+(0.33\ifmmode\pm\else\textpm\fi{}0.25){P}_{2}({cos\ensuremath{\theta}}^{\ensuremath{'}})].$ The total cross section for charge exchange, obtained by integration, is: ${\ensuremath{\sigma}}_{\mathrm{tot}}({\ensuremath{\pi}}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0})=7.7\ifmmode\pm\else\textpm\fi{}0.6$ mb at 61 Mev and ${\ensuremath{\sigma}}_{\mathrm{tot}}({\ensuremath{\pi}}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0})=13.2\ifmmode\pm\else\textpm\fi{}0.8$ mb at 95 Mev.A table summarizing the measurements performed by this group at 61 Mev, 95 Mev, 128 Mev, and 150 Mev is given.