The characteristics of a 50-cm-long module of the scintillation time-of-flight hodoscope have been studied. It has been determined that the coordinate resolution and detection efficiency of the module depend on the voltages applied to the voltage dividers of the photomultiplier tubes and the distance from the hip point of a particle to the photomultiplier tubes. The module has been tested using both a secondary electron beam of the Pakhra accelerator (Lebedev Physical Institute, Russian Academy of Sciences) with an energy of 20 MeV and a 90Sr+90Y radioactive source. The tests show that the minimum values of the coordinate resolution are σx ≈ 0.1 and 1.3 cm, respectively, and the detection efficiency is ε ≈ 53

A new precision three-arm magnetic spectrometer SCAN-3 is under construction for detecting charged (π, K, p) and neutral (n) particles produced at the LHEP Nuclotron internal target in dA collisions. This project is aimed at studies of highly excited nuclear matter. The matter will be studied through observation of its specific decay products, namely, pairs of energetic particles with a wide opening angle, close to 180°. The progress of work on the construction of the spectrometer will be discussed.

The scintillation amplitude−coordinate spectrometer with a thickness of 0.58X0 has been calibrated using cosmic radiation. The light signals in the spectrometer are detected by FEU-49 and FEU-85 photomultiplier tubes, which determine the amplitude and coordinate systems, respectively. It has been established that the relative amplitude and coordinate resolutions depend on the point of particle incidence on the spectrometer. The relative amplitude and coordinate resolutions measured at the center of the spectrometer appear to be the best, and their values are 8.7

The paper describes the design of a prototype magnetic field compensator intended to eliminate the influence of the edge magnetic field of the S-25P Pakhra accelerator magnet, Lebedev Physical Institute, on the electron beam during its output. The results of the study showed that this design could reduce an external magnetic field of B0 0.1 T to zero values inside the prototype.

— The characteristics of the calibration beam of secondary electrons at the Pakhra accelerator based on the SP-3 magnet at the Lebedev Physical Institute are presented. The energy resolution of a beam with a 2-mm-thick copper converter in the electron energy range E = 5–100 MeV is δ ≈ 10%.

The results of studies of the characteristics of the prototype of the scintillation time-of-flight hodoscope 71 cm long are presented. Prototype testing using a 90Sr + 90Y radioactive source showed that the coordinate resolution and detection efficiency depend on the source position on the work surface. The best coordinate resolution and the highest detection efficiency were found at the module center as σx ≈ 1.2 cm and ε ≈ 9

— A two-channel scintillation spectrometer with a thickness of 0.5 X 0 was calibrated using cosmic muons and a beam of secondary quasi-monochromatic electrons with energies of 3−100 MeV at the Pakhra accelerator оf the Lebedev Physical Institute. The scintillation signals were detected in the spectrometer by FEU-52 photomultiplier tubes. The dependences of the relative energy resolution of the individual spectrometer channels on the electron energy were found to be identical. The relative energy resolutions of the spectrometer channels and the sum of the signals from both channels were ~11 and ~7%, respectively, at an electron energy E ≈ 32 MeV.

A multichannel scintillation spectrometer with a thickness of 2.5X0 has been calibrated on a secondary electron beam with energies of 23−280 MeV at the Pakhra accelerator of the Lebedev Physical Institute. The relative energy resolution of the spectrometer is determined by the electron energy and the spectrometer thickness. The best relative energy resolution of the spectrometer is attained at an electron energy of ~90 MeV; its values are δ = 13 and 9.4% at spectrometer thicknesses of 1.0X0 and 2.5X0, respectively.

In this paper, we report the characteristics of the generated beams, the extracted electron beam and the beam of secondary electrons/positrons, of the LPI accelerator complex Pakhra as of November 2019 for testing and calibrating detectors used in large accelerator and astrophysical experiments. At energies of 250–500 MeV of the electron beam ejected into Hall 1 from the S-25R synchrotron, its energy resolution is δ ~ 1% and the intensity can be changed by collimators in the range of 10 3 –10 10 s –1 . The quasi-monochromatic beam of secondary electrons produced in Hall 2 typically has an energy in the range of 50–300 MeV, a corresponding energy resolution of δ = 14–2%, and an intensity of ~ 10 2 s –1 . The performed simulation of the characteristics of the secondary positron beam allowed selecting the optimal geometry of the setup and showed good agreement with the experimental data obtained later.

The calibration results are presented for a scintillation hodoscopic spectrometer of charged particles, which has been designed for an experiment on the search for a heavy electron on the bremsstrahlung photon beam at the Pakhra accelerator of the LPI. The relative energy and coordinate resolutions of the spectrometer at electron energy E = 40 MeV are δ = 22% and σx = 9.5 mm, respectively. It has been determined that the width of electromagnetic showers in the transverse direction can be described by the energy dependences Δ ~ lnE at E < 100 MeV and Δ ~ 1/expE at E > 100 MeV.

The results of cosmic-muon calibration of a shower lead-scintillation “sandwich”-type spectrometer of thickness 8.5X0, intended for operation in high-intensity photon and electron beams (~106 particles/s) with energies of 0.1–1.0 GeV are presented. It is found that the relative energy resolution of the spectrometer depends on the angle of cosmic muon entry into the spectrometer in the vertical plane and is independent of the entry angle into the horizontal plane. The relative energy resolution of the spectrometer is δ = 16%. Placing of an additional lead-scintillation assembly of thickness 2.2X0 in front of the spectrometer improved its relative energy resolution to δ = 9%.

The characteristics of the secondary electrons` calibration quasi-monochromatic beam of the accelerator S-25R "Pakhra" of the Lebedev Physical Institute of the Russian Academy of Sciences (LPI) on the basis of magnet SP-57 are presented. With an electron energy in the range of 45-280 MeV, a collimator diameter in front of the trigger counters of 3 mm and copper Converter thicknesses of 1-3 mm, the energy resolution and beam intensity were 4.4-2.2% and around 16 e/sec, respectively.

The characteristics of systems based on Cherenkov counters for monitoring the intensity of a bremsstrahlung photon beam at the S-25R Pakhra accelerator of the Lebedev Physical Institute are presented.

Characteristics of the neutron detector are investigated at the MARUSYA facility in the region of the F4 focus using an extracted deuteron beam from the Nuclotron accelerator (Laboratory of High Energy Physics, Joint Institute for Nuclear Research (LHEP JINR)). It is shown that the neutron detection efficiency is about 27%. With its time characteristics, the detector can be used in the SCAN-3 experimental facility for detecting nucleons from the decay of the η nucleus via the πn and pn channels.