Search results for "FLE"
showing 10 items of 3517 documents
Model-independent confirmation of theZ(4430)−state
2015
The decay $B^0\to \psi(2S) K^+\pi^-$ is analyzed using $\rm 3~fb^{-1}$ of $pp$ collision data collected with the LHCb detector. A model-independent description of the $\psi(2S) \pi$ mass spectrum is obtained, using as input the $K\pi$ mass spectrum and angular distribution derived directly from data, without requiring a theoretical description of resonance shapes or their interference. The hypothesis that the $\psi(2S)\pi$ mass spectrum can be described in terms of $K\pi$ reflections alone is rejected with more than 8$\sigma$ significance. This provides confirmation, in a model-independent way, of the need for an additional resonant component in the mass region of the $Z(4430)^-$ exotic sta…
Search for theZ(4430)−atBABAR
2009
We report the results of a search for Z(4430)^- decay to J/Ψ π^- or Ψ(2S)π^- in B(^-.0)→ J/Ψ π^-K^(0.+) and B^(-.0) → Ψ(2S)π^-K^(0.+) decays. The data were collected with the BABAR detector at the SLAC PEP-II asymmetric-energy e^+e^- collider operating at center-of-mass energy 10.58 GeV, and the sample corresponds to an integrated luminosity of 413 fb^(-1). Each K π^- mass distribution exhibits clear K^*(892) and K_2^*(1430) signals, and the efficiency-corrected spectrum is well described by a superposition of the associated Breit-Wigner intensity distributions, together with an S-wave contribution obtained from the LASS I=1/2 K π^- scattering amplitude measurements. Each K π^- angular dist…
Antihyperon potentials in nuclei via exclusive antiproton–nucleus reactions
2015
Abstract The exclusive production of hyperon–antihyperon pairs close to their production threshold in p ‾ -nucleus collisions offers a unique and hitherto unexplored opportunity to elucidate the behavior of antihyperons in nuclei. For the first time we analyze these reactions in a microscopic transport model using the Giesen Boltzmann–Uehling–Uhlenbeck transport model. The calculation takes the delicate interplay between the strong absorption of antihyperons, their rescattering and mean field deflection as well as the Fermi motion of the struck nucleon into account. We find a substantial sensitivity of transverse momentum correlations of coincident Λ ‾ Λ -pairs to the assumed depth of the Λ…
Recent results with lifetime enhanced microchannel-plate photomultipliers
2018
Abstract The favored photon sensors for the DIRC (detection of internally reflected Cherenkov light) detectors at the PANDA (Anti-proton Annihilation at Darmstadt) experiment at FAIR (Facility for anti-proton and ion research) are micro-channel-plate photomultipliers (MCP-PMTs). The main problem until a few years ago was the limited lifetime of the MCP-PMTs caused by a rapid decrease in quantum efficiency (QE) of the photo cathode (PC) with increasing integrated anode charge (IAC). These limitations are overcome by applying an atomic layer deposition (ALD) coating on the MCPs, as recently done by PHOTONIS and Hamamatsu. During the last years’ tests of lifetime enhanced MCP-PMTs were perform…
Breakthrough in the lifetime of microchannel plate photomultipliers
2015
Abstract Cherenkov detectors using the DIRC (Detection of Internally Reflected Cherenkov Light) principle are foreseen for particle identification in the P ¯ ANDA experiment at FAIR. Promising sensors for the detection of the Cherenkov light are the so-called micro-channel plate (MCP) photomultipliers (PMT). They have an excellent time resolution, can be operated at high gain for single photon detection and have a high resistivity against magnetic fields. The disadvantage of these devices was their limited lifetime, due to damage by feedback ions on the photocathode. The lifetime of various types of MCP-PMTs from different manufactures has been tested under conditions similar to that in the…
Simulation and reconstruction of the PANDA Barrel DIRC
2014
Hadronic particle identification (PID) in the barrel region of the PANDA experiment at the new Facility for Antiproton and Ion Research in Europe (FAIR) at GSI, Darmstadt will be provided by a DIRC (Detection of Internally Reflected Cherenkov light) counter. To optimize the performance and reduce the detector cost, detailed simulations of different design elements, such as the width of the radiators, the shape of the expansion volume, and the type of focusing system, were performed using Geant. Custom reconstruction algorithms were developed to match the detector geometry. We will discuss the single photon resolution and photon yield as well as the PID performance for the Barrel DIRC baseli…
Particle Identification with DIRCs at PANDA
2019
The DIRC technology (Detection of Internally Reflected Cherenkov light) offers an excellent possibility to minimize the form factor of Cherenkov detectors in hermetic high energy detectors. The PANDA experiment at FAIR in Germany will combine a barrel-shaped DIRC with a disc-shaped DIRC to cover an angular range of 5 to 140 degrees. Particle identification for pions and kaons with a separation power of 3 standard deviations or more will be provided for momenta between 0.5 GeV/c and 3.5 GeV/c in the barrel region and up to 4 GeV/c in the forward region. Even though the concept is simple, the design and construction of a DIRC is challenging. High precision optics and mechanics are required to…
The PANDA DIRC detectors
2020
Abstract The PANDA experiment at the future Facility for Antiproton and Ion Research (FAIR) will address fundamental questions of hadron physics with unprecedented precision. To reach this goal excellent Particle Identification (PID) is essential over a large range of particle momenta and solid angles. Most of the phase space will be covered by two innovative DIRC (Detection of Internally Reflected Cherenkov light) detectors. The Endcap Disc DIRC and Barrel DIRC will cover the polar angle range from 5 to 22°and 22 to 140°, respectively. Both detectors rely on high precision optical components, lifetime-enhanced Microchannel Plate PMTs (MCP-PMTs), and fast readout electronics.
Inverted-conical light guide for crosstalk reduction in tightly-packed scintillator matrix and MAPMT assembly
2015
Abstract In this paper we present the Inverted-Conical light guide designed for optical crosstalk reduction in the scintillator-MAPMT assemblies. The research was motivated by the 30% crosstalk observed in UFFO X-ray telescope , UBAT, during the preliminary calibration with MAPMTs of 64 2.88 × 2.88 mm2 pixels and identically gridded YSO crystal matrices. We began the study with the energy and crosstalk calibrations of the detector, then we constructed a GEANT4 simulation with the customized metallic film model as the MAPMT photocathode . The simulation reproduced more than 70% of the crosstalk and explained it as a consequence of the total reflection produced by the photocathode. The result…
Cubic boron nitride: A new prospective material for ultracold neutron application
2009
Abstract At the ultracold neutron (UCN) source of the TRIGA research reactor in Mainz, we have measured for the first time the material optical wall-potential of cubic boron nitride. The measurements were performed with a time-of-flight (TOF) spectrometer. The samples investigated had a wall-potential of ( 305 ± 15 ) neV . This value is in good agreement with the result extracted from neutron reflectometry data and theoretical expectations. Because of its high critical velocity for UCN and its good dielectric characteristics, cubic boron nitride coatings (isotopically enriched) will be useful for a number of applications in UCN experiments.