Progress in realization of the NICA project in JINR is outlined with special attention paid to results of the latest Nuclotron upgrades. The most important of them are (1) renewal of the polarized ...deuteron beam with kinetic energy up to
T
kin
∼ 5 GeV/nucleon, now available for experiments with fixed targets, and (2) successful acceleration in the Nuclotron (and extraction from it) of relativistic polarized protons.
The ϕ-Λ(1520) interference effect in the γp→K^{+}K^{-}p reaction has been measured for the first time in the energy range from 1.673 to 2.173 GeV. The relative phases between ϕ and Λ(1520) production ...amplitudes were obtained in the kinematic region where the two resonances overlap. The measurement results support strong constructive interference when K^{+}K^{-} pairs are observed at forward angles but destructive interference for proton emission at forward angles. Furthermore, the observed interference effect does not account for the sqrts=2.1 GeV bump structure in forward differential cross sections for ϕ photoproduction. This fact suggests possible exotic structures such as a hidden-strangeness pentaquark state, a new Pomeron exchange, or rescattering processes via other hyperon states.
A search for the K−pp bound state (the lightest kaonic nucleus) has been performed using the γd→K+π−X reaction at Eγ=1.5–2.4 GeV at LEPS/SPring-8. The differential cross section of the K+π− ...photo-production off deuterium (d2σ/dcosθK+lab/dcosθπ−lab) has been measured for the first time in this energy region. A peak structure was searched for in the inclusive missing mass spectrum. A statistically significant peak structure was not observed in the region from 2.22 to 2.36 GeV/c2. The upper limits of the differential cross section of the K−pp bound state production were determined to be (0.17–0.55), (0.55–1.7) and (1.1–2.9) μb at 95% confidence level with the assumed widths of 20 MeV, 60 MeV and 100 MeV.
Trigger System of the HyperNIS Experiment Averyanov, A. V.; Avramenko, S. A.; Aksinenko, V. D. ...
Physics of particles and nuclei letters,
11/2019, Letnik:
16, Številka:
6
Journal Article
Recenzirano
The trigger system of the HyperNIS spectrometer, which was proposed for distinguishing events with the formation and subsequent decay of relativistic hyperfragments, is described. The operation of ...the system is based on detecting the charges of the hyperfragment and the product nucleus in two-particle π
–
-meson decay. The events are selected using scintillation and Cherenkov counters. This article presents the results of a methodological work on updating the equipment and software of the experiment, describes the characteristics of trigger detectors, and discusses the specificities of using the trigger system in the planned experiment on the search for the
hypernucleus. The expected efficiency and noise immunity of the event selection system are estimated.
Time-of-Flight System of HyperNIS Spectrometer Averyanov, A. V.; Avramenko, S. A.; Aksinenko, V. D. ...
Physics of particles and nuclei letters,
11/2019, Letnik:
16, Številka:
6
Journal Article
Recenzirano
The main goal of the HyperNIS experiment is the search for the lightest neutron-rich hypernuclei, in particular,
and the poorly studied
and to measure the lifetimes and production cross sections of ...these hypernuclei. In order to measure the masses of the hypernuclei, it is necessary to determine the momenta of their decay products, including pions. The time-of-flight (TOF) method is planned to be used to measure the pion momenta. Simulation results show that this method provides sufficient accuracy for recovering the masses of the hypernuclei. The structure of the TOF system detectors and the results of the study of their characteristics are presented.
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