Yu. N. Kharzheev

Measurements of the K+→π0e+ν form factors

Abstract The q2 dependence of the vector form factor has been investigated using 3.2 × 104 K+ → π0e+ν decays. The usual linear parametrization. ƒ + (q 2 ) = ƒ(0)(1+λ + q 2 /m π 0 0 ) gives λ+ = 0.0284±0.0027. An analysis of the Dalitz plot density distribution for Ke3+ decays yields the values for the scalar and tensor couplings ƒs and ƒt, and their relative phase angle ost.

Use of silica aerogels in Cherenkov counters

Silica aerogel is widely used as a radiator for Cherenkov detectors. It is a highly porous, low-density, and transparent substance with refractive index n ranging between the values of n < 1.001 for gaseous and n ≈ 1.3 for condensed phases. The review is devoted to the consideration of various factors affecting the identification of particles in Cherenkov counters: the chromatic aberration, the number of photoelectrons, and the optical-system light transmittance. A brief review is given for principal methods of aerogel production, its manufacturers, optical and physical characteristics of aerogel samples, their transparency, scattering and absorption lengths, and number of photoelectrons. The use of silica aerogels in various threshold Cherenkov counters at such installations as BELLE (KEK), TASSO (DESY), and KEDR (VEPP-4M) is considered. In recent years, many research works have been carried out at the CERN proton synchrotron using various prototypes of Cherenkov counters. This review considers some of them. The progress achieved in manufacturing high-quality aerogel samples including the multilayer ones and the results of the tests were beneficial for implementing these materials in the Ring-imaging Cherenkov (RICH) counters at HERMES, developing the proximity focusing RICH detectors, and for proposing RICH detectors for the LHCb project at the CERN ring collider and at the Alpha Magnetic Spectrometer on the International Space Station.

Scintillation counters in modern high-energy physics experiments (Review)

Scintillation counters (SCs) based on organic plastic scintillators (OPSs) are widely used in modern high-energy physics (HEP) experiments. A comprehensive review is given to technologies for production of OPS strips and tiles (extrusion, injection molding, etc.), optical and physical characteristics of OPSs, and methods of light collection based on the use of wavelength-shifting (WLS) fibers coupled to multipixel vacuum and silicon PMs. Examples are given of the use of SCs in modern experiments involved in the search for quarks and new particles, including the Higgs boson (D0, CDF, ATLAS, CMS), new states of matter (ALICE), CP violation (LHCb, KLOE), neutrino oscillations (MINOS, OPERA), and cosmic particles in a wide mass and energy interval (AMS-02). Scintillation counters hold great promise for future HEP experiments (at the ILC, NICA, FAIR) due to properties of a high segmentation, WLS fiber light collection, and multipixel silicon PMT readout.

Energy resolution of a lead scintillating fiber electromagnetic calorimeter

A calorimeter module was fabricated using profiled lead plates and scintillating fibers with diameter 1 mm and attenuation length about 80 cm. The absorber-to-fiber volume ratio was 1.17 and the module average radiation length X0 ⋍ 1.05 cm. The energy resolution of the module was investigated using the electron beams of U-70 at Serpukhov and of the SPS at CERN in the energy range 5–70 GeV. The energy resolution at θ = 3° (the angle between the fiber axis and the beam direction) may be expressed by the formula σE (%) = 13.1E ⊕ 1.7. The energy resolution was also simulated by Monte Carlo and good agreement with the experiment has been achieved.

Modern trends in methods of charged particle identification at high energies

The survey is devoted to methods of charged particle identification at high energies that are based on measurements of the angle of Cherenkov radiation (ring imaging Cherenkov counters — RICH), of time of flight (TOF) and propagation (TOP), and of ionization energy loss (dE/dx). As an example, some operating spectrometers are considered (LHCb, ALICE, COMPASS, Belle, and BaBar) together with proposed ones (Belle-2 and PANDA) in which new achievements of recent years are introduced.

Increase in the light collection from a scintillation strip with a hole for the WLS fiber using filling materials of various types

The light collection of extruded scintillation strip samples with the help of WLS fibers placed in a longitudinal hole inside of the plates has been measured. The holes are filled with various liquid fillers. Measurements are performed under irradiation by cosmic muons. A method for pumping a liquid filler with a viscosity of more than 10 Pa s into the strip hole with a WLS fiber inside is devised and successfully tested.

Optimization of light yield by injecting an optical filler into the co-extruded hole of the plastic scintillation bar

Results of the measurements with cosmic muons for the light yield of 2-meter long extruded scintillation bar (strip) as a function of distance for different options for light collection technique are presented. Scintillation strip cross section geometry was a triangle made on polystyrene plastic scintillator with dopants of 2% PTP and 0.03% POPOP, extruded with 2.6 mm diameter hole and produced at ISMA (Kharkov, Ukraine). It was shown that the insertion of the optical transparent resin (BC 600 or CKTN MED(E)) by special technique into the co-extruded hole with 1.0 mm or 1.2 mm wave-length shifter (WLS) fiber Kuraray Y11 (200) MC in it significantly improves light collection by factor of 1.6...1.9 against of the dry case.

Results of mass testing of mini drift tubes for the D0 forward muon system

The procedures and results of mass testing of mini drift tubes in the course of their production for the D0 forward muon system (Tevatron, Fermilab) are described. High-voltage training, checking the stability and uniformity of signals induced by X rays, measuring the wire tension, and leak testing are included in the testing procedure. Owing to the fast and effective testing of detectors under conditions of mass production, the quality of the mini drift tubes is such that virtually no tubes are finally rejected during assembly of the detector system.

Investigation of inclusive production ofK0 andK* (892)0 mesons inK+A interactions at 11.2 GeV

AbstractInclusive production ofK0 andK* (892)0 mesons inK+A-interactions (A=Be, Cu, Pb) at the energy 11.2 GeV has been investigated to study hadronisation of the leadingn