V. A. Baskov

Electromagnetic showers induced by high energy electrons in aligned tungsten crystals

Abstract The experimental results of the development of electromagnetic showers induced by 28 GeV electrons in aligned tungsten crystals with thicknesses 0.07,0.3,1.0mm are presented. At this energy of electrons the “constant strong field” effect starts to show and the development of showers in aligned crystals is distinguished from the one in an amorphous substance.

The time resolution of a prototype neutron detector

The time characteristics of a prototype neutron detector designed for measuring the time of flight and determining the coordinate of the interaction point of a high-energy neutron on the detector have been investigated on cosmic rays. The time resolutions of the prototype neutron detector and the monitoring system are σ ≈ 0.7 and 0.2 ns, respectively.

Spectrometers for Recording Electromagnetic Showers Emerging from Oriented Crystals

The design and main characteristics of combined shower spectrometers (CSSs) are presented: combined Cherenkov and lead-scintillation spectrometers that are intended for investigating shower processes in oriented crystals and that consist of ten independent lightproof counters with thicknesses of 1X0 and 1.18X0, respectively. At an electron energy Ee = 26 GeV, the energy resolutions of both CSSs together with a Cherenkov spectrometer with a thickness of 15X0, which was placed behind them, were 2.4 and 4.3% for the combined Cherenkov and lead-scintillation shower spectrometers, respectively.

Neutron Activity of Thunderstorm Storm

The results of measurements of the diffusion neutron flux from the thunderstorm storm occurred in Moscow in the night from July 13 to 14, 2016 at a distance ~30 km from detectors are presented. An increase in the frequency of coincidences of four channels of two scintillation detectors by ~10% with respect to coincidences in the absence of thunderstorm is found. The neutron yield in a single lightning discharge is estimated as ~1010 n/s.

The time characteristics of a single module of the neutron detector

The time characteristics of the scintillation plate that is an element of the neutron detector designed for measuring the energy of a neutron by its time of flight and determining the coordinate of the point of its interaction with the detector have been investigated on cosmic rays. The time resolutions of the neutron detector element measured with P9814B and FEU-63 photomultiplier tubes are σ ≈ 0.14 and 0.29 ns, respectively.

Effect of an oriented crystalline converter on the electromagnetic spectrometer response

The results of the experimental studies of the response of an electromagnetic spectrometer with a converter made of 〈111〉 tungsten crystal at electron energies of 26, 28, and 31 GeV are presented. It is found that the ratio of the difference between positions of the cascade curve maximum for misoriented and oriented converter to the difference between energy releases at the cascade curve maximumis a constant value at a given electron energy, converter type and thickness, and is independent of the converter temperature.

Spectrometer–telescope calibration by cosmic muons

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.

Radiation length of the oriented crystal

The radiation length X0′ of the 〈111〉 tungsten crystal is not a constant, and depends on the crystal temperature and thickness, and the electron energy. The radiation length estimated at the temperature Tdisorient at which the crystal becomes almost an amorphous material incapable of orientation is X0d′ ∼ 9 mm.

Effect of crystal temperature on parameters of electromagnetic shower

Parameters of electromagnetic showers developed in a 1-mm disoriented tungsten crystal and in the same crystal oriented along the 〈111〉 axis depend on crystal temperature. The position of the maximum of the electromagnetic-shower development and the energy release in the maximum for a shower going out of a crystal and continuing the development in a spectrometer are linearly dependent on crystal temperature. The temperature at which the crystal orientation becomes impossible was estimated as approximately 980 K.

Critical energy of anomalous electron-induced showers

The results of experimental studies of anomalous electromagnetic showers caused by electrons with energies of tens of GeV, emerging from oriented tungsten crystals and detected by an electromagnetic spectrometer, are presented. An approximately twofold increase in the critical energy ɛc of the anomalous shower development in comparison with the similar quantity in the case of the standard shower development is detected. Its behavior is studied as a function of the crystal orientation, thickness, temperature, and the electron energy.