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.

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.

The results obtained by measuring, at the U-70 accelerator in Protvino, the single-spin asymmetry A N in the reaction p + p └ → π0 + X at a beam energy of 50 GeV in the Feynman variable range of −0.6 < x F < −0.1 are presented. The asymmetry A N is close to zero at small |x F | and grows in magnitude with |x F |, reaching 6.4% in the region of |x F | > 0.25. The results of these measurements agree with data of the E704 experiment on the asymmetry of π 0 mesons at the Fermi National Accelerator Laboratory in the region of polarized-beam fragmentation and with the results of measurements in the region of polarized-target fragmentation that were performed in Protvino by using a 40-GeV π −-meson beam and a 70-GeV proton beam.

A new experiment SPASCHARM devoted to a systematic study of polarization phenomena in hadron-hadron interactions in the energy range 10-70 GeV is under preparation at IHEP (Protvino). The physical observables will be single-spin asymmetries, hyperon polarizations and spin-density matrix elements. A universal setup will detect and identify various neutral and charge particles in the full azimuthal angle and a wide polar angle range. A polarized target is used to measure the SSA. The SPASCHARM sub-detectors are being designed and constructed now. The possibility of obtaining a polarized proton beam for the SPASCHARM experiment from Lambda decays is under study.

The first stage of the proposed polarization program SPASCHARM includes the measurements of the single-spin asymmetry (SSA) in exclusive and inclusive reactions with production of stable hadrons and the light meson and baryon resonances.In this study we foresee of using the variety of the unpolarized beams (pions, kaons, protons and antiprotons) in the energy range of 30-60 GeV. The polarized proton and deuteron targets will be used for revealing the flavor and isotopic spin dependencies of the polarization phenomena. The neutral and charged particles in the final state will be detected.

The fine-sampling electromagnetic calorimeter prototype has been experimentally tested using the 1-19 GeV/c tagged beams of negatively charged particles at the U70 accelerator at IHEP, Protvino. The energy resolution measured by electrons is Delta{E}/E=2.8%/\sqrt{E} + 1.3%. The position resolution for electrons is Delta{x}=3.1 + 15.4/sqrt{E} mm in the center of the cell. The lateral non-uniformity of the prototype energy response to electrons and MIPs has turned out to be negligible. Obtained experimental results are in a good agreement with Monte-Carlo simulations.

An automated setup for measuring single-spin asymmetry in inclusive neutral-meson production at the 14th channel of the IFVE accelerator (IHEP) is described. The experiments were conducted using both the secondary pion beam with 40-GeV/c momentum and the primary proton beam with 70-GeV energy, brought to the setup zone by means of a bent single crystal. The main characteristics of the detectors and data-acquisition system are presented.