The system of magnetic measurements in large volumes based on Hall probes has been developed in the Institute for High Energy Physics (IHEP). An example of its practical use to measure the topography of the spectrometric magnet’s field of the SPASCHARM experiment at the U-70 accelerator complex is described. In these measurements, the special attention has been paid to calibrations, monitoring the stability of parameters, and of the accuracy in positioning the probes in the magnet aperture and in their orientation. Further development of the system and the study of its capabilities for improving the accuracy, reducing the measurement time and, in general, increasing its flexibility in applications are also presented.

The results on the extraction of a proton beam of a varying intensity from the U-70 accelerator using bent silicon single crystals are presented. Stable beam extraction using crystals has been demonstrated for two experiments where smooth adjustment of the beam intensity over a large dynamic range has been required.

Data taking has been started at the first stage of the SPASCHARM experiment on systematic study of the spin effects in strong interactions. The current setup configuration is described, and the detector characteristics attained during the beam data taking in the runs of 2018–2022 are listed.

First results on Alpha-dependence measurements in inclusive K-S(0) meson production in pi(-)Alpha interactions (Alpha=C, Al, Cu, Sn, and W) are presented at approximate to 26.5 GeV/c. The ratios of the differential cross sections of four of these nuclei to the differential cross section on aluminum were measured and the dependence of these cross sections on the atomic of the nucleus was studied. The measurements were carried out in the kinematic region of the Feynman variable 0.2 < x(F) < 0.8 and transverse momentum p(T) < 1.2 GeV/c. K-S(0) mesons were detected in the decay mode K-S(0)->pi(+)pi(-) at the SPASCHARM experimental setup using negative charged beams at beamline 14 of the U-70 accelerator complex.

The study of spin effects in elastic proton–proton and antiproton–proton scattering in the SPASCHARM experiment at U-70 accelerator facility (Institute for High Energy Physics, National Research Centre Kurchatov Institute, Protvino, Moscow oblast) is discussed. Polarized beams or a polarized target of the experiment will be used to measure the analyzing power A_N of elastic scattering of protons and antiprotons. The possibility of using two different types of the detectors to register recoil particles of elastic scattering of protons is analyzed. In the first case, it is proposed to use scintillation counters, the second option is a detector based on proportional chambers. A comparison of the registration efficiency of elastic pp scattering for two configurations of the experimental setup is carried out, and the required measurement time is determined.

The study of spin effects in elastic proton-proton and antiproton-proton scattering in the SPASCHARM experiment at U-70 accelerator facility (Institute for High Energy Physics, National Research Centre Kurchatov Institute, Protvino, Moscow oblast) is discussed. Polarized beams or a polarized target of the experimentwill be used to measure the analyzing powerAN of elastic scattering of protons and antiprotons. The possibility of using two different types of the detectors to register recoil particles of elastic scattering of protons is analyzed. In the first case, it is proposed to use scintillation counters, the second option is a detector based on proportional chambers. A comparison of the registration efficiency of elastic pp scattering for two configurations of the experimental setup is carried out, and the required measurement time is determined.

The spectra of the optically detected magnetic resonance for single NV– centers have been experimentally studied in two solid-state samples in the range of hyperfine interactions between the electron spin and the nitrogen nucleus spin in the same NV– center. This study has been aimed at reaching a maximal microwave frequency resolution in the experimental setup used. For measurements, two low-nitrogen (no higher than 50 ppb) diamond single-crystal samples have been grown. Measured time T_2^* of the spin decoherence in NV– centers was about 2 μs in one sample and 20 μs in the other. For both samples, the spectrum of the optically detected magnetic resonance for the hyperfine splitting of a single NV– center and 14N atom has been taken and investigated. The resolution in these samples has been estimated at a level of 3.5 and 0.18 MHz, respectively. It has been noted that the resolution of the spectrum improves with increasing time T_2^* of the spin decoherence of the single NV– center.

First results on 𝐴-dependence measurements in inclusive K0𝑆-meson production in 兀− 𝐴-interactions (𝐴 = C, Cu, Al, Sn, W) are presented at 26.5 GeV/c. The ratios of the differential cross sections of four of these nuclei to the differential cross section on aluminum were measured and the dependence of these cross-sections on the atomic number of the nucleus was studied. The measurements were carried out in the kinematic region of the Feynman variable 0.2 < 𝐹 < 0.8 and transverse momentum 𝑝𝑇 < 1.2 GeV/c. K0𝑆-mesons were detected in the decay mode K0𝑆→ 兀+兀−-at the SPASCHARM experimental setup using negative charged beams at beamline 14 of the U-70 accelerator complex.

First results on the polarization of Λ hyperons inclusively produced on 26.5-GeV/c K^ - and π^ - beams are presented. The measurements were carried out using the SPASCHARM setup at the U-70 accelerator facility (Protvino, Russia) on nuclear targets in 2021 and 2022. The polarization of an Λ hyperon on the π^ - beam does not exceed several percent in most of the studied kinematic region. The data obtained on the K^ - -meson beam exhibit a significant positive polarization at large values of the Feynman variable xF and transverse momentum pT measured for the first time on nuclei.

First results on A -dependence measurements in inclusive K_S^0 meson production in π^-A interactions ( A=C , Al, Cu, Sn, and W) are presented at ≈26.5 GeV/c. The ratios of the differential cross sections of four of these nuclei to the differential cross section on aluminum were measured and the dependence of these cross sections on the atomic of the nucleus was studied. The measurements were carried out in the kinematic region of the Feynman variable 0.2

The possibility of using NV-defects in diamond at room temperature on nanometer spatial scales to measure magnetic fields was studied. For these purposes, samples with high concentrations of NV-centers are usually used, which increases the signal level but prevents the measurement of inhomogeneous fields on the scale of molecules or nanostructures. The parameters of a weak magnetic field were measured taking into account Earth's field by measuring the hyperfine structure of the optically detected magnetic resonance spectrum to calibrate and determine the resolution of a magnetic field sensor on a single NV-defect.

The main goal of the SPASCHARM experiment is the systematic study of spin phenomena at intermediate energies. For this purpose, it is planned to create a beam of polarized protons and antiprotons. The research includes, among other things, the study of elastic scattering. Some of the required equipment for polarimetry is planned to be also used to study elastic scattering immediately after the creation of such a channel. In this work, a set of observables necessary for model-free reconstruction of elastic proton–proton scattering amplitudes is investigated and determined.

A system of four magnets which is a part of the SPASCHARM experimental setup at the U-70 accelerator facility for the study of spin effects in hadronic interactions is described. An unique magnet with the field of 2.4 T and a field uniformity at the level of 10–4 in a working volume of 60 cm3 is used to pump up and hold polarization in a polarized proton frozen target. A special wide-aperture magnet is the central part of the spectrometer of the setup based on the drift tubes. For precision steering the beam to the center of the target, two small magnets correctors developed by the Efremov Research Institute of Electrophysical Equipment have been manufactured and introduced into the setup.

A method of vector magnetometry, implemented using a single NV–13C spin system in a diamond, is proposed. The method is based on a priori knowledge of the hyperfine interaction characteristics and on the presence of experimentally measured line positions in the optically detectable magnetic resonance spectrum of such a system. The method was experimentally tested on the NV–13C system, in which the 13С atom is located in the third coordination sphere of the NV center.

Data taking has been started at the first stage of the polarization experiment SPASCHARM at U-70 accelerator. This report describes the detectors of the current experimental setup as well as the results of measurements of their characteristics during the beam data taking in the runs of 2018–2022.