No Arabic abstract
The paper describes a method of the charged particle identification, developed for the mbox{CMD-3} detector, installed at the VEPP-2000 $e^{+}e^{-}$ collider. The method is based on the application of the boosted decision trees classifiers, trained for the optimal separation of electrons, muons, pions and kaons in the momentum range from 100 to $1200~{rm MeV}/c$. The input variables for the classifiers are linear combinations of the energy depositions of charged particles in 12 layers of the liquid xenon calorimeter of the mbox{CMD-3}. The event samples for training of the classifiers are taken from the simulation. Various issues of the detector response tuning in simulation and calibration of the calorimeter strip channels are considered. Application of the method is illustrated by the examples of separation of the $e^+e^-(gamma)$ and $pi^+pi^-(gamma)$ final states and of selection of the $K^+K^-$ final state at high energies.
The Belle-II experiment and superKEKB accelerator will form a next generation B-factory at KEK, capable of running at an instantaneous luminosity 40 times higher than the Belle detector and KEKB. This will allow for the elucidation of many facets of the Standard Model by performing precision measurements of its parameters, and provide sensitivity to many rare decays that are currently inaccessible. This will require major upgrades to both the accelerator and detector subsystems. The imaging Time-of-propagation (iTOP) detector will be a new subdetector of Belle-II that will perform an integral role in Particle identification (PID). It will comprise 16 modules between the tracking detectors and calorimeter; each module consisting of a quartz radiator, approximately 2.5m in length, instrumented with an array of 32 micro-channel plate photodetectors (MCP-PMTs). The passage of charged particles through the quartz will produce a cone of Cherenkov photons that will propagate along the length of the quartz, and be detected by the MCP-PMTs. The excellent spatial, and timing resolution (of 50 picoseconds) of the iTOP system will provide superior particle identification capabilities, particularly allowing for enhanced discrimination between pions and kaons that will be essential for many of the key measurements to performed. The status of the construction of the iTOP subdetector, and performance studies of prototypes at beam tests will be presented, together with prospects for physics measurements that will utilise the PID capabilities of the iTOP system.
We have constructed a liquid Argon TPC detector with fiducial mass of 150 kg as a part of the R&D program of the next generation neutrino and nucleon decay detector. This paper describes a study of particle identification performance of the detector using well-defined charged particles (pions, kaons, and protons) with momentum of ~800 MeV/$c$ obtained at J-PARC K1.1BR beamline.
This article reviews the progress made over the last 20 years in the development and applications of liquid xenon detectors in particle physics, astrophysics and medical imaging experiments. We begin with a summary of the fundamental properties of liquid xenon as radiation detection medium, in light of the most current theoretical and experimental information. After a brief introduction of the different type of liquid xenon detectors, we continue with a review of past, current and future experiments using liquid xenon to search for rare processes and to image radiation in space and in medicine. We will introduce each application with a brief survey of the underlying scientific motivation and experimental requirements, before reviewing the basic characteristics and expected performance of each experiment. Within this decade it appears likely that large volume liquid xenon detectors operated in different modes will contribute to answering some of the most fundamental questions in particle physics, astrophysics and cosmology, fulfilling the most demanding detection challenges. From experiments like MEG, currently the largest liquid xenon scintillation detector in operation, dedicated to the rare mu -> e + gamma decay, to the future XMASS which also exploits only liquid xenon scintillation to address an ambitious program of rare event searches, to the class of time projection chambers like XENON and EXO which exploit both scintillation and ionization of liquid xenon for dark matter and neutrinoless double beta decay, respectively, we anticipate unrivaled performance and important contributions to physics in the next few years.
The EXO-200 Collaboration is searching for neutrinoless double beta decay using a liquid xenon (LXe) time projection chamber. This measurement relies on modeling the transport of charge deposits produced by interactions in the LXe to allow discrimination between signal and background events. Here we present measurements of the transverse diffusion constant and drift velocity of electrons at drift fields between 20~V/cm and 615~V/cm using EXO-200 data. At the operating field of 380~V/cm EXO-200 measures a drift velocity of 1.705$_{-0.010}^{+0.014}$~mm/$mu$s and a transverse diffusion coefficient of 55$pm$4~cm$^2$/s.
A large-area Multi-Pixel Photon Counter (MPPC) sensitive to vacuum ultra violet (VUV) light has been developed for the liquid xenon (LXe) scintillation detector of the MEG II experiment. The LXe detector is designed to detect the 52.8,MeV photon from the lepton flavour violating decay $mu^+ to mathrm{e}^+ gamma$ and is based on $900,ell$ LXe with a highly granular scintillation readout by 4092 VUV-MPPCs with an active area of $139,mathrm{mm}^2$ each, totalling $0.57,mathrm{m}^2$. The VUV-MPPC shows an excellent performance in LXe, which includes a high photon detection efficiency (PDE) up to 21% for the LXe scintillation light in the VUV range, a high gain, a low probability of the optical cross-talk and the after-pulsing, a low dark count rate and a good single photoelectron resolution. The large active area of the VUV-MPPC is formed by connecting four independent small VUV-MPPC chips in series to avoid the increase of the sensor capacitance and thus, to have a short pulse-decay-time, which is crucial for high rate experiments. Performance tests of 4180 VUV-MPPCs produced for the LXe detector were also carried out at room temperature prior to the installation to the detector and all of them with only a few exceptions were found to work properly. The design and performance of the VUV-MPPC are described in detail as well as the results from the performance tests at room temperature.