Yu.K. Akimov

Fields of Application of Aerogels (Review)

The properties of silica aerogel and other types of aerogels are described. Basic information about their manufacture processes is presented. The application of aerogels in optics, nuclear physics, low-temperature physics, laser experiments, space investigations, microelectronics, electrical engineering, and acoustics as highly efficient heat insulators and trapping media for the analysis or purification of gas or liquid flows that pass through them is considered.

Experimental apparatus for studying the interaction of antiprotons with light nuclei

Abstract A description is given of the detector system (self-shunted streamer chamber in a magnetic field) used in the PS-179 experiment at LEAR for studying antiproton interactions with light nuclei.

Silicon radiation detectors (Review)

The modern status of the field of development of silicon detectors of charged particles and x/γ rays is considered. The types and characteristics of spectrometric detectors are briefly described; the predominant attention is given to track devices. The results of studies of the radiation resistance of silicon detectors are presented.

Timing system for Ge(Li) detectors

Abstract A timing system for coincidence and nuclear lifetime measurements with Ge(Li) detectors is described. The timing discriminator, based on the ARC-principle, is designed using integrated circuits. Uncompensated pulses from low energy events near the threshold of the timing discriminator are eliminated by a special internal coincidence circuit. Output pulses caused by noise, are excluded by duration discrimination. The detector signals are amplified by a preamplifier and a fast amplifier with 2.5 and 3.5 ns risetimes, respectively. The time resolution has been obtained 15.6, 2.7 and 1.1 ns fwhm for energies 50, 511 and 1330 keV, respectively, by using a planar detector (1.9 cm 3 ) with a collection time of 40 ns. The differential peak shift in the range from 10 to 1330 keV was 1.2 ns.

An aerogel threshold Cherenkov counter

The results of a study of the properties of aerogel manufactured at the Laboratory of Nuclear Problems, Joint Institute for Nuclear Research, are presented. The technology of the production of aerogel samples and the optical characteristics of these samples are briefly described. A formula relating the refractive index of the aerogel to its density with regard to the dispersion of light is analyzed. The results of testing of an aerogel threshold Cerenkov counter are presented. Testing was performed using a beam of charged particles with momenta p ranging from p = ∼ 0.4–2.5 GeV/с. The efficiency of pion detection with p ≥ 1 GeV/с was ∼97%; the efficiency of proton detection with p ≤ 2.5 GeV/c, ∼4%.

Timing System for Ge(Li)-Detectors

A timing system for coincidence and nuclear lifetime measurements with Ge(Li)-detectors is described. The timing discriminator, based on the ARC-principle, is designed using integrated circuits. Uncompensated pulses from low energy events near the threshold of the timing discriminator are eliminated by a special internal coincidence circuit. Output pulses caused by noise, are excluded by duration discrimination. The detector signals are amplified by a preamplifier and a fast amplifier with 2.5 and 3.5 nsec risetimes,respectively. The time resolution has been obtained 15.6 , 2.7 and 1.1 nsec FWHM for energies 50, 511 and 1330 keV, respectively, by using of a planar detector (1.9 cm3) with a charge collection time of 40 nsec. The differential peak shift in a range from 10 to 1330 keV was 1.2 nsec.

Cherenkov Detectors in Particle Physics

The most impressive examples of the application of Cherenkov detectors in modern-physics experiments are considered.

THE SEPARATING OF PARTICLES ACCORDING TO THEIR IONIZATION VALUE IN SEVERAL SCINTILLATION COUNTERS

Abstract A telescope of scintillation counters is described by means of which it is possible to register rare processes of particle emission with high ionization and small range against a background of outside radiation with smaller ionization. Both normal plastical scintillators 6 mm thick and filmlike scintillators 0.5 mm thick on a polistirole base with the addition of 1% of tetraphenylbutadien were used in the counters. The counting responses of the telescope are given for the separation of deuterons from protons with the impulse p =900 MeV/ c , nuclei He 3 from deutrons with the impulse p =730 MeV/ c , and also for α-particles with the energy 800 MeV. The apparatus here described has been used in experiments, investigating the processes: p+d→ π + +H 3 , d+d→He 3 +n, d+d→ π 0 +He 4 .

A Low-Noise Fast Eight-Channel Preamplifier

A preamplifier with a rise and fall time of ∼2.5 ns is described. At the output of a transmitting 50-Ω cable with matched terminations at both ends, and the input-equivalent circuit noise is 20 μV at an amplification factor of 7.5. Eight such preamplifiers are placed inside a unit with dimensions of 8 × 16 × 4 cm.

Positive-pion absorption on carbon at low pion energies

Abstract The total cross section of positive-pion absorption on carbon with a two-proton final state at pion energies of 26–39 MeV has been measured. At a pion energy of 28.5 MeV some narrow structure exists in the energy dependence of the cross section.