Powerful Particle Identification Research Articles

Particle identification with the NA62 RICH detector

NA62 is a new generation kaon experiment at the CERN SPS aiming at studying rare and forbidden decays. One of main challenges of the experiment is the suppression of background decay channels with branching ratios up to 10 orders of magnitude higher than the signal and with similar experimental signatures. To provide such suppression, a powerful particle identification (PID) is needed.A key element of PID in NA62 is the Ring Imaging Cherenkov (RICH) detector. The RICH has successfully operated during the 2016–2018 data taking periods, being essential in the measurement of the branching ratio of the K+→π+νν̄ decay. The detector was also used for searches for lepton number violation in 3-track kaon decays. The results on the π/μ and π/e separation directly measured with the data for the aforementioned decays are presented.

A neural network classifier for electron identification on the DAMPE experiment

The Dark Matter Particle Explorer (DAMPE) is a space-borne particle detector and cosmic ray observatory in operation since 2015, designed to probe electrons and gamma rays from a few GeV to 10 TeV in energy, as well as cosmic protons and nuclei up to 100 TeV. Among the main scientific objectives is the precise measurement of the cosmic electron + positron flux, which, due to the very large proton background in orbit, requires a powerful particle identification method. In the past decade, the field of machine learning has provided us the needed tools. This paper presents a neural network based approach to cosmic electron identification and proton rejection and showcases its performance based on simulated Monte Carlo data. The neural network reaches significantly lower background than the classical, cut-based method for the same detection efficiency, especially at the highest energies probed by the detector. Good agreement between simulation and real data is demonstrated.

Dielectron simulations for the CBM-TRD

This report features the simulation studies of dielectron decays with the compressed baryonic matter experiment in the regime of high net-baryon densities and moderate temperatures. The corresponding region in the QCD phase-diagram is completely unexplored with leptonic channels and could provide essential insight into potential phase transitions to a QGP-phase or chiral symmetry restoration. At CBM energies there is undisturbed access to the decay channel of prompt thermal photons into dielectron pairs in the intermediate mass range between 1.1 and 2.5 GeV/c. Due to the rare character of such electromagnetic probes, very high statistics and a powerful particle identification are crucial. With the combination of a RICH detector and the TRD, CBM will measure these signals with a sufficient significance, as will be demonstrated in this work.

First test of an enriched $$^{116}$$ 116 CdWO $$_4$$ 4 scintillating bolometer for neutrinoless double-beta-decay searches

For the first time, a cadmium tungstate crystal scintillator enriched in $^{116}$Cd has been succesfully tested as a scintillating bolometer. The measurement was performed above ground at a temperature of 18 mK. The crystal mass was 34.5 g and the enrichment level ~82 %. Despite a substantial pile-up effect due to above-ground operation, the detector demonstrated a high energy resolution (2-7 keV FWHM in 0.2-2.6 MeV $\gamma$ energy range), a powerful particle identification capability and a high level of internal radiopurity. These results prove that cadmium tungstate is an extremely promising detector material for a next-generation neutrinoless double-beta decay bolometric experiment, like that proposed in the CUPID project (CUORE Upgrade with Particle IDentification).

Design and status of the Mu2e electromagnetic calorimeter

The Mu2e experiment at Fermilab aims at measuring the neutrinoless conversion of a negative muon into an electron and reach a single event sensitivity of 2.5×10−17 after three years of data taking. The monoenergetic electron produced in the final state, is detected by a high precision tracker and a crystal calorimeter, all embedded in a large superconducting solenoid (SD) surrounded by a cosmic ray veto system. The calorimeter is complementary to the tracker, allowing an independent trigger and powerful particle identification, while seeding the track reconstruction and contributing to remove background tracks mimicking the signal. In order to match these requirements, the calorimeter should have an energy resolution of O(5)% and a time resolution better than 500ps at 100MeV. The baseline solution is a calorimeter composed of two disks of BaF2 crystals read by UV extended, solar blind, Avalanche Photodiode (APDs), which are under development from a JPL, Caltech, RMD consortium. In this paper, the calorimeter design, the R&D studies carried out so far and the status of engineering are described. A backup alternative setup consisting of a pure CsI crystal matrix read by UV extended Hamamatsu MPPC׳s is also presented.

Search for Dark Matter in Cosmic Rays with the AMS-02 space spectrometer

The cosmic rays spectrometer AMS-02 will be placed on the ISS Space Station in April 2011 and should take data for at least 10 years. After a short review of the impressive observational data collected in the last few years by satellites and underground experiments in the quest for Dark Matter (DM), we describe the AMS-02 space spectrometer with its powerful particle identification capabilities. The performances of the experimental apparatus and the perspectives opened by this new powerful observational instrument for the DM search will be briefly reviewed. In particular the extension at the TeV scale of the positron and electron spectra with high statistical significance well beyond the PAMELA results will hopefully clarify the quest for Dark Matter evidence in cosmic rays. Finally the present status of the AMS-02 payload for the Shuttle transportation and installation on the International Space Station, and the implementation of the Control Center for data collection and analysis is reviewed.

RICH for [formula omitted

The powerful particle identification detection system of the P ¯ ANDA (antiProton ANihilations at DArmstadt) experiment contains three Cherenkov detectors. In the forward direction a conventional RICH detector is planned. In the high solenoid field of the target spectrometer thin Cherenkov detectors using the DIRC principle are mandatory and are envisaged in the form of a barrel and a vertical disc. The combination of the time of arrival of the photons with their spatial image determines not only the particle velocity, but also the wavelength of the photons. Therefore dispersion corrections on the lower and upper detection threshold is possible. Investigations concerning the development of a 3D-Barrel-DIRC are discussed as well as two different studies realizing a new Disc-DIRC for the forward angles. One is based on the Time of Propagation (ToP) method the other on the readout with focusing light guides.

Status of the LHCb silica aerogel Cherenkov radiator

A powerful particle identification capability is required for the LHCb physics programme. Two RICH detectors provide π / K separation between 1–100 GeV/ c , using three radiators. Low–momentum particles, up to 10 GeV/ c , are identified by Cherenkov light produced in silica aerogel. R&D results on the aerogel from test–beam and laboratory studies are presented.

Search for pentaquarks in the hadronic decays of the Z boson with the DELPHI detector at LEP

The quark model does not exclude states composed of more than three quarks, like pentaquark systems. Controversial evidence for such states has been published in the last years, in particular: for a strange pentaquark Θ ( 1540 ) + ; for a double-strange state, the Ξ ( 1862 ) − − , subsequently called Φ ( 1860 ) − − ; and for a charmed state, the Θ c ( 3100 ) 0 . If confirmed, a full pentaquark family might exist; such pentaquark states could be produced in e + e − annihilations near the Z energy. In this Letter a search for pentaquarks is described using the DELPHI detector at LEP, characterized by powerful particle identification sub-systems crucial in the separation of the signal from the background for these states. At 95% CL, upper limits are set on the production rates 〈 N 〉 of such particles and their charge-conjugate state per Z decay: 〈 N Θ + 〉 × Br ( Θ + → p K S 0 ) < 5.1 × 10 −4 , 〈 N Θ + + 〉 < 1.6 × 10 −3 , 〈 N Φ ( 1860 ) − − 〉 × Br ( Φ ( 1860 ) − − → Ξ − π − ) < 2.9 × 10 −4 , 〈 N Θ c ( 3100 ) 0 〉 × Br ( Θ c ( 3100 ) 0 → D ∗ + p ¯ ) < 8.8 × 10 −4 .

The RICH with Aerogel for the LHCb Experiment

Silica aerogel is one of the three radiators chosen for the Ring Imaging Cherenkov system of the LHCb experiment, designed to provide a powerful particle identification tool. Aerogel, in the RICH detector [1], covers the momentum range 1−10 GeV/c for π/K separation. The material is a hygroscopic quality of silica aerogel produced by the Boreskov Institute for Catalysis in collaboration with the Budker Institute of Nuclear Physics in Novosibirsk. A big effort has been put during the last few years to obtain large size tiles with high transparency and good uniformity with respect to refractive index variations from point to point, to the level of 1% of (n − 1), with n =1 .03 at λ = 543. 5n m. At the end of this R&D period, large size silica aerogel tiles with unprecedented optical quality have been delivered to us for testing, making it realistic to achieve the requested resolution in the Cherenkov angle measurement.

π± Spectra in Au+Au Collisions at $\sqrt{s_{\rm NN}}=62.4\ {\rm GeV}$

The combination of the ionization energy loss (dE/dx) from Time Projection Chamber (TPC) at ≃ 8% resolution and multi-gap resistive plate chamber time-of-flight (TOF) at 85ps provides powerful particle identification. We present spectra of identified charged pions from transverse momentum pT≃0.2 GeV/c to 7-8 GeV/c in Au + Au collisions at [Formula: see text]. Physics implications will be discussed.

Selex results on [formula omitted] and [formula omitted] production

The SELEX experiment (E781) is a 3-stage magnetic spectrometer for a high statistics study of hadroproduction of charm baryons out to large χ F using 650 GeV/ c Σ −, π − and p beams. The main features of the spectrometer are: a high precision silicon vertex system; powerful particle identification provided by TRD and RICH; forward decay spectrometer; and 3-stage lead glass photon detector. Preliminary results on asymmetry for D s ±, D −, D ∗± and D 0/ D 0 produced by Σ −, π − beams at χ F > 0.2 are presented. The results show significant non-perrtubative effects that are not explained by any present model.

Recent results from selex

The SELEX experiment (E781) is a 3-stage magnetic spectrometer for a high statistics study of hadroproduction of charm baryons out to large x F using 650 GeV Σ −, π − and p beams. The main features of the spectrometer are: a high precision silicon vertex system; powerful particle identification provided by TRD and RICH; forward Λ s decay spectrometer; and 3-stage lead glass photon detector. Preliminary results on asymmetry for Λ c produced by Σ −, π − and p beams at x F > 0.2 and precise measurements of the Λ c , D 0, and preliminary D s lifetimes are presented.

First results from the Selex Collaboration

The SELEX experiment (E781) is 3-stage magnetic spectrometer for a high statistics study of hadroproduction of charm baryons out to large gc F using 650 Gev Σ − , π − and p beams. The main features of the spectrometer are: a high precision silicon vertex system, powerful particle identification provided by TRD and RICH, forward Λ s decay spectrometer and 3-stage lead glass photon detector. An experiment overview and description of spectrometer features are shown. Preliminary reconstructed charm states and results on Λ c , D + particles and antiparticles produced by Σ − , π − and p beams at χ F > 0.3 are presented. Asymmetry for Λ c production is also discussed.

Applications of nuclear track-recording solids to high-energy phenomena

Abstract The density of defects along the track left by a nuclear particle in a non-conducting solid provides a permanent record of the particle's velocity, charge, and mass. The record can be deciphered by etching the solid in a suitable reagent and measuring the sizes of the etch pits at points of intersection of the track with the surfaces. Useful solids include minerals and glasses which are sensitive only to particles with a charge/velocity ratio Z/β≳150, and polymers, the most sensitive of which detects particles with Z/β as low as 6. Numerous applications of this powerful particle identification technique to relativistic nucleus–nucleus collisions, particle physics, and high-energy particles in space are discussed.