Strangeness in Hadronic Matter and Study of Inelastic Reactions
Near Kinematical Borders

Participating countries and international organizations:

Belarus, Czech Republic, Japan, Russia, Slovakia, Ukraine.

Issues addressed and main goals of research:

Strangeness in hadronic matter and study of boundary effects:

– study of stabilizing effects of strangeness in nuclear matter and properties of the lightest hypernuclei;

– study of multi-particle dynamics in the inelastic proton-proton and proton-nucleus interactions with extremally high multiplicity;

– study of spectra and yields of soft photons in the deuteron-nucleus and nucleus-nucleus interactions.

Expected results upon completion of the theme stages or projects:

1. Experimental conclusion about the existence of the hypernucleus ⁶_ΛН.

2. New experimental data on the properties of the lightest hypernuclei and experimental verification of corresponding theoretical models for these hypernuclei.

3. New experimental data on the drip-line location for loosely bound light hypernuclei with high neutron excess, necessary for the development of the theory of neutron-rich hyper nuclei and models of their production in non-central nucleus-nucleus interactions.

4. New experimental data on the production of strangeness and vector mesons (including those, containing strange quarks) by polarized photons (close to the relevant thresholds).

5. Measurement of the measured energy spectra of gamma-quanta (in the energy range up to several MeV), produced in the interactions of different nuclear beams (from deuterium to heavy nuclei) of Nuclotron with various nuclear targets, with theoretical predictions depending on the multiplicity of charged and neutral particles, as well as on the photon emission angle; verification of various physical hypotheses about the mechanisms of production of "direct" photons in the nuclear interactions.

6. Production of an electromagnetic calorimeter prototype for detecting soft photons and testing it on the "Alpom" facility and the "MiniSPD" test bench.

Expected results in the current year:

1. Data taking for ⁶_ΛH search using beam of ⁷Li nuclei. Analysis of the first experimental data for the ⁶_ΛH search and for the measurements of hyperhydrogen isotopes ⁶_ΛH and ⁴_ΛH lifetimes.

2. Upgrade of the HyperNIS magnetic spectrometer (tracking system) by adding the planes of GEM detectors. These detectors, which have already been (partially) purchased and are being tested at the HyperNIS setup by staff, will be integrated into this setup to improve accuracy of the hyper nucleus decay vertex determination. Preparation of a project for joint experiments with SRC, integration of detectors, development of a technical design for a spectrometer with two magnets (installations of a second magnet, supply of communications, supports for detectors), common data acquisition systems (design and tests), MC for the optimal geometry of joint detectors.

3. Within the collaboration with Japan: data taking at LEPS/LEPS2 setups on the production of strangeness and vector mesons (including those, containing strange quarks) by polarized photons (close to the relevant thresholds); analysis of data on such reactions, taken before.

4. Development of silicon photomultipliers (SiPM) for a compact soft photon spectrometer based on the Gadolinium Gallium Garnet (GaGG:Ce). Investigation of the percentage ratio of the Cu-W components of the composite material as radiators of the soft photon calorimeter. Manufacture of silicon photomultipliers (SiPM) at “Integral” holding (Minsk). Development and manufacture of a calibration device based on a picosecond solid-state laser in cooperation with the PFP Research Institute (Minsk).

5. Participation in the simulation of the calorimeter use in the SPD setup for the task of direct photon registration, within the development of the SPD physical program with polarized beams of light nuclei and protons. Participation in works on simulation of the polarimeters (to be created) for experiments with polarized beams at the VBLHEP accelerator complex.

6. Preparing a new project to replace the one being completed.

7. Comparison of the average of the transverse and longitudinal momentum components of charged particles as a function of multiplicity. Determination of the critical multiplicity at which the components become indistinguishable and establishing its connection with the pion condensate region.