The results of cosmic muon calibration of the extended quadrihedral NaI(Tl) spectrometer are presented. The signal amplitude and energy resolution of the spectrometer in the direction transverse to the spectrometer axis have complex dependences on the photomultiplier voltage and particle entrance point to the spectrometer. At a photomultiplier divider voltage U = 1150 ± 10 V, the region of uniform signals is observed over ~90% of the spectrometer length, the relative energy resolution is δ ≈ 7%.

When the half-ring of a prototype neutron detector with an inner radius of 50 mm is calibrated using a 60Co ionizing-radiation source, its relative detection efficiency gradually decreases from ~15% at the center of the half-ring to ~5% at its ends. When calibrated using cosmic muons, the relative detection efficiency is approximately 100% over the entire detector volume. The presence of zones with reduced and increased efficiency values are associated with the intricate detector geometry.

The results of cosmic-muon calibration of the multichannel lead–scintillation “sandwich”-type spectrometer–telescope intended for operation in high-intensity photon and electron beams, capable of determining the beam energy and forming intrinsic trigger, are presented. It was found that the relative energy resolution at an average energy release by cosmic muons in the spectrometer of ∼26 MeV is from 7.5% to 23% depending on the internal and external trigger version.

Cosmic-ray calibration of the 4-channel lead scintillation monitor with internal trigger shows that the consideration of only coinciding signals of counters placed in the monitor depth and detecting the final part of the high-energy photon shower, with signals of any other counters at the monitor top, detecting both the initial part of the high-energy photon shower and low-energy background photons, decreases the number of detected coincidences by a factor of 2–4. An increase in the number of such coincidences when using the monitor in the setup for studying neutral pion photoproduction on nuclei in the photon beam of the labeling system of the “PAKHRA” accelerator of the Lebedev Physical Institute makes it possible to separate the high-energy electromagnetic shower from the low-energy background and to monitor the beam photon energy.

member of the Russian Academy of Sciences, DSc in Physics and Mathematics, celebrated his 70th birthday. He was born on May 4, 1937 in Moscow, into a family of university teacher-researchers. Having graduated with a gold medal from famous Moscow school No. 110 in 1955, he enrolled in the physics department of the Moscow State University and graduated from there cum laude in 1961; he was accepted to continue as a graduate student. Denisov began his research career at the end of the 1950s in P A Cherenkov's Photomeson Laboratory of the P N Lebedev Physics Institute (FIAN). He took part, under guidance of B B Govorkov, in experiments on photoproduction of p-mesons and in construction the first-ever setup for photon `tagging' using the particle beam extracted from the 265 MeV synchrotron. Nowadays, the `tagged' photon technique is widely used in many accelerator centers worldwide. The results of this work became the subject of Denisov's PhD thesis, ``Experimental investigation of photoproduction of p-mesons in complex nuclei near the threshold,'' submitted and defended in 1964. In March 1964 he began working at the Institute of High Energy Physics (IHEP). Together with Yu D Prokoshkin, Denisov became a leading scientist in the preparation and launching of first-priority experiments in the IHEP particle accelerator, which at the start of operations in 1967 produced protons with energy twice higher than that of the largest accelerators in the world. Denisov was able to solve a most important problem for experiments in the now accessible energy range, namely the reliable identification of particles. A group of physicists led by Denisov designed and built a special set of unique Cherenkov gas counters (threshold and differential) with record resolution in particle velocity. Among these, they created a 10-meter differential Cherenkov helium-filled counter with particle velocity resolution db=b ˆ 2 10ÿ6 and extremely low background (less than 10ÿ6). They also created threshold Cherenkov counters with resolution db=b ˆ 6 10ÿ6 and background level 3 10ÿ4. Differential and threshold counters with such record characteristics are capable to separate particles of different masses in beams with energies of hundreds of GeV. Denisov thus succeeded in solving the problem of particle identification not only for the IHEP accelerator but for accelerators of the next generations as well. Reliable identification of particles made it possible to discover in the IHEP accelerator experiments such very important features of hadron interactions as the increase of the total cross-sections with increasing energy and scale invariance (`scaling') in hadron production. These discoveries were made by a joint IHEP±CERN group in the historically first joint experiment whose co-leader from our side was Denisov. The increase of total cross sections was discovered in K‡p-interactions. It was far from easy to detect this effect as the growth in cross section in the momentum range from 15 to 55 GeV/c was only a few percent while the fraction of K‡-mesons in the beam at the 55 GeV/c momentum was only 5 10ÿ3. Subsequent experiments with more powerful accelerators showed that the growth in total cross sections discovered at IHEP is a universal phenomenon for all hadrons. As a result, some theoretical concepts had to be substantially reconsidered. In 1972Denisov submitted and defended his DSc thesis, ``Measuring total cross sections of interactions of pions, kaons, and antiprotons with protons and deuterons in the momentum range up to 65 GeV/c.'' In 2002 Denisov won the P A Cherenkov Prize of the Russian Academy of Sciences for the discovery of the total cross sections growth (so called `Serpukhov effect'); in 1986 he received the Lenin Prize for scale invariance discovery (together with Prokoshkin, M A Mestvirishvili, and Nguen Van Hieu). The Cherenkov counters developed by Denisov played an important role in discovering the nuclei of antihelium-3 in experiments at IHEP in which he also took part. In 1974 Denisov supervised the launching of the Sigma universal spectrometer which was then used to study elastic scattering of positive particles by protons and to carry out the Uspekhi Fizicheskikh Nauk 177 (5) 581 ± 582 (2007) Translated by V I Kisin PERSONALIA PACS number: 01.60.+q

An ionization detector—a shower axis spectrometer—is used to detect high-intensity (106–1012 particles/s) photon and electron beams. The main characteristics of this spectrometer are presented.

Сергей Петрович Денисов (к 70-летию со дня рождения), Барков Л.М., Герштейн С.С., Говорков Б.Б., Иванов С.В., Кадышевский В.Г., Лобашев В.М., Логунов А.А., Матвеев В.А., Образцов В.Ф., Сисакян А.Н., Скринский А.Н., Тюрин Н.Е.

The structure of a composite photon-electron spectrometer based on NaI(Tl) crystals and plastic scintillators is described. A spectrometer calibration under a beam of secondary electrons with an energy of 50-150 MeV is described. At a work-load of N similar to 10(3) Hz the energy resolution is sigma/E = 0.03E(-0.25), and the time resolution is similar to 8 nsec.

Oriented crystals make it possible to improve the separation of high-energy electrons and hadrons. Experimental results on the degree of separation of 26-GeV/c electrons moving along the [111] crystallographic axis of tungsten crystals from electrons with momenta in other directions are reported.

The radiation losses for 28 GeV electrons in the [111] axis-oriented tungsten crystals of the 1 and 0,3 mm thickness are measured. The radiation loss calculations performed in the framework of the coherent theory and constant field approximation agree with the experimental data within the 10% accuracy. The relative radiation losses of electrons with the energy below 1 GeV in the same crystals are given.

For a long time it was understood that process of the pion photo-production on nuclei can be used as the information source about the photoproduction amplitudes on nucleons.