Search

In the Laboratory of High-Energy Physics, 16-channel prototypes of detectors (with SiPM readout produced by Ketek and Hamamatsu) were developed for their application in zero-degree calorimetry and for measuring the profile of a low-energy neutron beam. This paper presents the method for determining the voltage of the breakpoint of the noise characteristic of silicon photomultipliers in the multichannel detector and its temperature dependence in the range from 27.7°C to 39.1°C. The response of SiPM to the LED source of calibrated light pulses has been studied and the time resolution has been obtained.

The results from studies of the differential cross section of elastic deuteron–proton scattering at 500–1000 MeV/nucleon on the Nuclotron Internal Targets Station are presented and compared to the available experimental data for similar energies, and to the results of theoretical calculations in the theory of relativistic multiple scattering.

The aim of the deuteron spin structure (DSS) experiment is to obtain polarization observables in dp elastic scattering and in dp breakup at large CMS angles (> 60°). The dp breakup reaction has been investigated by the scintillation detectors placed at the vicinity of the Internal Target Station (ITS) of Nuclotron. Calibration data have been obtained at the deuteron energy of 300 - 500 MeV. The main goal of this report is to present the calibration procedure of the ΔE - E detectors. Calibration coefficients are used to recover the deposited particle energy.

The paper presents measurements of the noise characteristics of silicon photomultipliers in the temperature range from 27.7 °C to 39.1 °C, as well as study of the response of the detector prototypes with Ketek and Hamamatsu SiPM readout to the light source at different voltages. The prototype with SiPM readout from Ketek was tested at the Joint Institute for Nuclear Research Nuclotron deuteron beam at the energy of 4 GeV/nucleon. Time resolution and amplitude of the signal have been estimated.

Analyzing power in elastic proton-proton scattering was obtained at the Nuclotron Internal Target Station using a polarized deuteron beam and a polyethylene target. The selection of useful events was performed using the time and amplitude information from scintillation counters. The asymmetry on hydrogen was obtained by the subtraction of the carbon background. The obtained analyzing power values are compared with the predictions of the partial-wave analysis SAID at the beam energies of 500 and 650 MeV/nucleon.

The the polarimeter upgrade program at the Nuclotron internal target is presented. This polarimeter is intended for polarization experiments to study of the spin structure of two- and three-nucleon systems. The simulation of the pd-elastic and pp-elastic scattering for 500 - 1000 MeV proton energy to optimize the experimental setup and the first test of new detectors are performed.

Deuteron spin structure program is aimed on extraction of two and three nucleon forces information, including their spin dependent parts, from dp elastic and dp breakup processes investigated at intermediate energies. The dp elastic data were obtained at Internal Target Station of Nuclotron (JINR) in the energy range 400-1800 MeV using polarized deuteron beam. Strong sensitivity to the short range spin structure of the isoscalar nucleon-nucleon correlations is observed in deuteron analyzing powers. Preliminary results of the the cross section for the dp breakup reaction have been obtained at 400 MeV of deuteron energy.

Polarized and unpolarized data for the dp breakup reaction at deuteron energies of 270, 400 MeV and 300–500 MeV using \(\varDelta E - E\) technique are obtained. Dp elastic scattering has been investigated using polarized deuteron beam under various kinematic configurations in the angular range (\(65^{\circ }\)–\(135^{\circ }\)) in c.m. at deuteron energies of 400, 700, 800, 1000, 1100, 1300, 1500 and 1800 MeV. Preliminary results of analyzing powers obtained in dp elastic scattering at 800 MeV of deuteron energy are compared with the calculations based on relativistic multiple scattering model.

Calibration procedure of ΔE − E detectors used in dp breakup reaction measurement in the framework of DSS project is discussed. Time information from all PMTs along with amplitude information and known energy values of pp quasi elastic reaction are used to find calibration coefficients for ΔE and E detectors. Calibration coefficients are used to recover deposited particle energies. ΔE vs. E plots, energies and missing mass spectra are compared with geant4 Monte Carlo simulation. Missing mass for particular physical configuration is calculated as a test of the calibration procedure quality.

The results of measurements of the differential cross section for elastic deuteron–proton scattering at the energy of 700 MeV per nucleon that were performed at the internal target station of the nuclotron at the Joint Institute for Nuclear Research (JINR, Dubna) are presented. These data were obtained at angles in the range between 70◦ and 120◦ in the c.m. frame. The angular dependence obtained in this way is compared with world-averaged data at similar energies and with the results of theoretical calculations performed within the relativistic theory of multiple scattering.

We present recent results on the investigation of the KETEK, ZECOTEK, HAMAMATSU and SENSL SiPM properties after irradiation by the 6–35 MeV neutrons. The typical neutron fluence was about 1012n/cm2. The changing of the internal structure of the irradiated SiPMs was studied by the measuring of the C–V and C–f characteristics. We have observed the strong influence of the SiPM manufacturing technology on their radiation hardness. The application of the obtained results to the development of the readout electronics is discussed.

The eight-channel high-voltage power supply system based on using the Wenzel Elektronik N1130 module is described. The characteristics of 8DAC-12 and 8ADC-14 types control modules of CAMAC standard designed for high-voltage systems are presented. This system was successfully used to provide the power supply of scintillation detectors in the experiments on the study of the structure of light nuclei at JINR Nuclotron.

The results on the differential cross section of dp elastic scattering obtained at the Internal Target Station at the Nuclotron JINR at the energies of 500, 750 and 900MeV/nucleon are presented. The measurements have been performed using an unpolarized deuteron beam and polyethylene foil target. The data have been obtained in the angular range of $ 70^{\circ}$ - $ 120^{\circ}$ in the cms. The angular dependences of the data from the present experiment are compared with the world experimental data obtained at nearby energies as well as with the theoretical calculations performed within the relativistic multiple scattering theory. The behavior of the differential cross section at the fixed scattering angles covering the total cms energy region of $ \sqrt{s} = 3.1 -3.42$ GeV is in qualitative agreement with the s power-law dependence.

The current deuteron beam polarimetry at the Nuclotron is provided by the Internal Target polarimeter based on the use of the asymmetry in dpelastic scattering at large angles in the cms at 270 MeV. The upgraded deuteron beam polarimeter has been used to obtain the vector and tensor polarizations during 2016/2017 runs for the DSS experimental program. The polarimeter has been also used to tune the polarized ion source parameters for 6 different spin modes. The data analysis has been performed using the developed software based on C++ language and ROOT5 library

The current deuteron beam polarimetry at Nuclotron is provided by the Internal Target polarimeter based on the use of the asymmetry in dp-elastic scattering at large angles in the cms at 270 MeV. The upgraded deuteron beam polarimeter has been used to obtain the vector and tensor polarization during 2016 runs for the DSS experimental program. The polarimeter has been used also for tuning of the polarized ion source parameters for 6 different spin modes. The data analysis has been performed using developed software based on C++ language and ROOT5 library.

Preliminary results on the angular distributions of the vector Ay and tensor Ayy, Axx analyzing powers in dp elastic scattering at the energy of 800 MeV are presented. The measurements have been performed on Internal Target Station of the JINR Nuclotron using polarized deuteron beam from new source of polarized ions. The experimental data are compared with the preliminary calculations obtained within framework of relativistic multiple scattering approach.

The results on the angular dependencies of the vectorAyand tensorAyyandAxxanalyzing powers in deuteron-proton elastic scattering at large scattering angles are presented. These data were obtained at internal target at the JINR Nuclotron in the energy range 400-1800 MeV using polarized deuteron beam from new polarized ion source. New data on the deuteron analyzing powers in the wide energy range demonstrate strong sensitivity to the short-range spin structure of the isoscalar nucleon-nucleon correlations observed earlier. The perspectives of further studies of the short-range correlations using carbon, polarized deuteron and proton beams are discussed.

The Beam Beam Counter is a system for local polarimetry and local luminosity monitoring at the Spin Physics Detector at NICA. The main option of the Beam Beam Counter is the scintillation counters with SiPM readout. The work presents the first results on scintillation detector prototype using developed Front-end electronics based on the Time-over-Threshold technique. The procedure of the time-walk correction is discussed.

The results on the vector Ay and tensor Ayy and Axx analyzing powers in deuteronproton elastic scattering at large transverse momenta are presented. These data were obtained at internal target at JINR Nuclotron in the energy range 400-1800 MeV using polarized deuteron beam from new polarized ion source. New data on the deuteron analyzing powers in in the wide energy range demonstrate the sensitivity to the short-range spin structure of the isoscalar nucleon-nucleon correlations.

The results of the Polarimeter upgrade at the Nuclotron internal target are presented. This Polarimeter is intended for experiments to study of the spin structure of two-nucleon and three- nucleon short-range correlations. The measurements are performed in the frame of the DSS project. The simulation of the pd-elastic and pp-elastic scattering for 500 - 1000 MeV proton energy to optimization of the experimental setup is performed.

The dp breakup reaction has been investigated by the scintillation detectors placed at the vicinity of Internal Target Station (ITS) of Nuclotron. Data have been obtained at the angles of 19° - 54° in the laboratory frame at the deuteron energy of 300 - 500 MeV in a various detector configurations in which the sensitivity to the three nucleon correlations and relativistic effects are assumed. Preliminary results of the five fold differential cross section for particular detector configurations of the dp breakup reaction at 400 MeV of deuteron energy have been obtained.

The polarization observables are sensitive to the two nucleón (2NF) and three-nucleon structures (3NF) of the nuclei. The aim of the deuteron spin structure (DSS) experiment is to obtain polarization observables in dp elastic scattering at large CMS angles (> 60°) and in dp breakup. Of great importance is the study of polarizations observables in these reactions at intermediate energies because the experimental and theoretical data are very scarce. In this review, results of vector and tensor analyzing powers obtained at JINR Nuclotron at 800 MeV will be presented.

The current deuteron beam polarimetry at Nuclotron is provided by the Internal Target polarimeter based on the use of the asymmetry in dp- elastic scattering at large angles in the cms at 270 MeV. The upgraded deuteron beam polarimeter has been used obtain the vector and tensor polarization during 2016/2017 runs for the DSS experimental program. The polarimeter has been used also for tuning of the polarized ion source parameters for 6 different spin modes.

The main goal of the deuteron spin structure project is to investigate the spin structure of nucleon–nucleon and three nucleon short-range correlations via the measurements of the polarization observables in the deuteron induced reactions at intermediate energies at Nuclotron (Dubna, Russia). In this framework, dp nonmesonic breakup and dp elastic reactions are investigated using internal target station. The dp breakup data are obtained with the detection of two outgoing protons at the angles of $$19^{\circ }$$ – $$54^{\circ }$$ in lab. frame at the deuteron energies of 300–500 MeV. The data of dp elastic scattering for the deuteron energies up to 2000 MeV are obtained in angular range $$70^{\circ }$$ – $$120^{\circ }$$ in cm. The further perspectives of the investigations using polarized deuteron beam as well as the studies of the $${}^3{\mathrm{He}}(d,p){}^4{\mathrm{He}}$$ reaction are discussed.

We report on measurements of neutral pion production in the inclusive reactions d + C → π 0 + x and d + Cu → π 0 + x at an incident momentum of 4.5 GeV/c per nucleon. The experiments were performed on the LHE 90-channel lead glass γ -spectrometer. The cross sections were measured over the kinematical region specified by the inequalities θπ ≤ 16° and Eπ ≥ 2 GeV (in the laboratory frame). The cumulative number and transverse momentum dependencies of the exponent n in the invariant cross section parameterization Ed 3 σ / d 3 p ~ A t n are investigated by comparing of the observed cross sections for π 0 production on carbon and copper targets in the intervals 0.6 ≤ X ≤ 1.8 and 0.04 ≤ p T 2 ≤ 0.40 (GeV/c)2 . The double differential cross section for the reaction d + C → π 0 + x is measured using statistics of about 4.5 · 104 π 0 mesons. On the basis of these data we verified the so-called cluster mechanism of π 0 production. We have compared our data for the reaction d + C → π 0 + x , extrapolated to θπ = 0°, with the data from another experiments on π − production: d + C → π − (0°) + x (P = 1.75 and 2.88 GeV/c per nucleon) [1]; p + d → π − (180°) + x and p + d → π + (180°) + x (P = 8.9 GeV/c per nucleon) [2]; d + p → π − (0°) + x (P = 8.9 GeV/c per nucleon) [3]. The invariant cross sections were approximated by an exponential function Ed 3 σ / d 3 p ~ exp (−X / X 0 ). The slope parameter X 0 at different kinetic energies of the projectiles in the range of 1.05÷8.0 GeV per nucleon is determined.

Recent results on the deuteron analyzing powers in dp- elastic scattering obtained at Nuclotron (JINR, Dubna) are compared with the calculations performed within relativistic multiple scattering model. The data demonstrate strong deviation form the predictions at large angles in the cms. The preliminary data on the energy dependence of the cross section in the dp → ppn reaction at 150–250 MeV/nucleon for different configurations and dp elastic scattering up to 1 GeV obtained at internal target station at Nuclotron are reported. The prospects of the further few-body studies at JINR are discussed.

Experimental results concerning the kaon yield in the reaction d + Be → K±(0°) + X for values of the cumulative variable xc in the range between 0.88 and 1.37 are presented. Values in the region of xc ≥ 1 correspond to short nucleon-nucleon distances (deuteron-core region) at which nucleon wave functions begin overlapping each other, forming a cluster (flucton) where the hadron-matter density is higher than the average matter density in the nucleus. The behavior of the K+/K− yield ratio in this region may be interpreted within the hypothesis that the quark sea in nuclei becomes harder because of the presence of a flucton component in nuclear matter.

Results of analysis of the effective mass spectra of photon pairs produced in dC, dCu and pC interactions at momenta of 2.75, 3.83 and 5.5 GeV/c per nucleon, respectively, are presented. A structure at effective mass of about 38 MeV/c2 is observed. The results of testing the observed signal are presented. The test results support the conclusion that the observed signal is the consequence of detection of a particle with a mass of about 38 MeV/c2 decaying into a pair of photons.

The results of the differential cross section of elastic dp-scattering measurements at 500, 750 and 900 MeV/n, performed at the Internal Target Station at the JINR Nuclotron are presented. The angular dependence is compared with the world experimental data at close energies as well as with the theoretical calculations performed within the framework of the relativistic multiple scattering theory. The differential cross section at fixed scattering angles covered a total c.m. energy range $\rad{}{s} = 3.1 - 3.42\,{\rm{GeV}}$ were obtained. The results are compared with the behavior of the world data.

The results on the cross-section of dp -elastic scattering obtained at 400-880 MeV at internal target at Nuclotron are presented. The measurements have been performed using CH 2 and C targets and kinematic coincidence of signals from scintillation counters.

The experiment on dp non-mesonic breakup at Internal Target Station at Nuclotron-M is presented. The first results on the study of the dp-breakup reaction with 300-500 MeV unpolarized deuteron beam are discussed. Selection procedure of useful events for the dp→ppn reaction with the registration of two protons is shown.

The results on the cross-section of dp-elastic scattering reaction obtained at 500, 700 and 880 MeV at the internal target of Nuclotron are presented. The measurements have been performed using CH2 and C targets and kinematic coincidence of signals from scintillation counters. The cross-section data are compared with theoretical predictions and results of previous experiments.

The new control system of the Nuclotron (JINR, Dubna) internal target is described in both hardware and software aspects. The CAMAC hardware is based on the use of the standard CAMAC modules developed and manufactured at JINR. The internal target control and data acquisition (IntTarg CDAQ) system software is implemented using the ngdp framework under the Unix-like operating system (OS) FreeBSD to allow easy network distribution of the online data collected from internal target and accompanying detectors, as well as the internal target remote control.

Along with $ \pi^{0}$ and $ \eta$ mesons, a resonance structure in the invariant-mass spectrum of two photons at $ M_{\gamma\gamma} = 360 \pm 7 \pm 9$ MeV is observed in the reaction $ d C \rightarrow \gamma + \gamma +X$ at momentum 2.75GeV/c per nucleon. Estimates of its width and production cross section are $ \Gamma = 64 \pm 18$ MeV and $ \sigma_{\gamma\gamma} = 98 \pm 24^{+93}_{-67}$ μb, respectively. The collected statistics amount to $ 2339 \pm 340$ events of $ 1.5\cdot 10^{6}$ triggered interactions of a total number $ \sim 10^{12}$ of $ d+C$ interactions. This resonance structure is not observed in the $ \gamma$ $ \gamma$ channel in $ \sim 10^{11} p+ C$ collisions at the beam momentum 5.5GeV/c . The result obtained in the reaction $ d+ C$ is confirmed by the second experiment carried out on the deuteron beam at momentum 3.83GeV/c per nucleon with a copper target: $ M = 382 \pm 13$ MeV, $ \Gamma = 62 \pm 37$ MeV and $ \sigma = 273 \pm 75$ μb. Some results on the observation of the resonance in the invariant-mass spectra of two $ \pi^{0}$ mesons are presented: the data obtained in the $ d+C\rightarrow \gamma+\gamma + X$ reaction is confirmed by the results for the $ d+C\rightarrow \pi^{0} +\pi^{0} + X$ and $ p+C\rightarrow \pi^{0} +\pi^{0} + X$ reactions; a preliminary estimate of the ratio $ Br(R\rightarrow\gamma\gamma)/Br (R\rightarrow\pi^{0}\pi^{0})$ is $ (1.8-3.7)\cdot 10^{-3}$ . Further studies of this resonance is assumed at the Nuclotron/NICA at higher setup acceptance, which will allow to elucidate the nature of this resonance by determination of the differential cross sections at different beam energies in the range 1-6GeV/n and the mechanism of its formation.

Experimental and theoretical studies of direct photon production in hadronic collisions essentially expand our insights in multiparticle production mechanisms. These photons are useful probes to investigate nuclear matter at all stages of the interaction. Soft photons play a particular role in these studies. Until now we have no explanation for the experimentally observed excess of soft photons. These photons have low transverse momenta \( p_{T} < 0.1\) GeV/c, \( \vert x\vert < 0.01\) . In this domain their yield exceeds the theoretical estimates by 5-8 times. The registration of soft photons at Nuclotron (LHEP, JINR) has been carried out by the electromagnetic calorimeter built by the SVD-2 Collaboration. Soft photon electromagnetic calorimeter was tested at U-70, IHEP (Protvino). For the first time the soft photon yield at interactions of 3.5A GeV/c per nucleon deuterium and lithium beams has been measured. The obtained energy spectra confirm the increased yield of soft photons with their energy less than 50MeV (in the laboratory system) in comparison with theoretical predictions and agree with previous experiments at high-energy interactions. It is planned to continue soft photon study at the future accelerator complex NICA with heavy-ion beams.

The results of the first extraction of the 3.42 A GeV 12C beam at Nuclotron and its transportation to the experimental area is presented. It is demonstrated that the beam parameters are sufficient for the first phase of the experiments on the studies of the dense baryonic matter at Nuclotron.

Along with $\pi^0$ and {\eta} mesons, a resonance structure in the invariant mass spectrum of two photons at M{\gamma}{\gamma} = 360 \pm 7 \pm 9 MeV is observed in the reaction d + C \rightarrow {\gamma} + {\gamma} + X at momentum 2.75 GeV/c per nucleon. Estimates of its width and production cross section are {\Gamma} = 64 \pm 18 MeV and $\sigma_{\gamma\gamma}$ = 98 \pm 24 {\mu}b, respectively. The collected statistics amount to 2339 \pm 340 events of 1.5 \cdot 10^6 triggered interactions of a total number ~ 10^12 of dC-interactions. The results on observation of the resonance in the invariant mass spectra of two $\pi^0$ mesons are presented: the data obtained in the d + C \rightarrow {\gamma} + {\gamma} reaction is confirmed by the d + C \rightarrow $\pi^0$ + $\pi^0$ reaction: $M_{\pi^0\pi^0}$ = 359.2 \pm 1.9 MeV, {\Gamma} = 48.9 \pm 4.9 MeV; the ratio of Br(R\rightarrow{\gamma}{\gamma}) / Br(R\rightarrow$\pi^0\pi^0$) = (1.8 {\div} 3.7)\cdot10^-3.

A complex of detection equipment based on scintillation detectors for investigating dp elastic scattering at the internal target of the Nuclotron developed in the framework of the Deuteron Spin Structure (DSS) project is presented. The results of optimizing scintillation detectors and the results of test measurements of a deuteron beam of the Nuclotron are given.

A selection of dp-elastic scattering events at energies of 1.6 and 2.0 GeV by using scintillation counters has been performed. The procedure of the CH2-C subtraction has been established. The dependence of the elastic events yield on the filter thickness has been investigated. This method can be used to develop the efficient high-energy deuteron beam potarimetry.

The experiment on dp non-mesonic breakup at Internal Target Station at Nuclotron-M is presented. The first results on the study of the dp-breakup reaction with 500 MeV unpolarized deuteron beam are discussed. Selection procedure of useful events for the d p → p p n reaction with the registration of two protons is shown.

The preliminary results on the cross-section of dp -elastic scattering reaction obtained at 880 and 500 MeV at internal target of Nuclotron are presented. The measurements have been performed using CH 2 and C targets and kinematic coincidence of signals from scintillation counters. The cross-section data at 880 MeV are compared with the different theoretical predictions.

Experimental results on the vector (A y ) and tensor (A yy ) analyzing powers in the fragmentation of 5- and 9-GeV/c polarized deuterons to high-momentum pions in the kinematical region corresponding to pion production on a strongly correlated nucleon pair (cumulative meson production) are presented. The angular and momentum dependences of A yy are not described by calculations performed in the impulse approximation by using standard deuteron wave functions. An explanation for our data should be sought on the basis of models that treat the deuteron at short distances (deuteron-core region) as a multiquark state—for example, a 6q cluster, whose high orbital angular momentum (D wave) leads to the observed strong dependence of the reaction tensor analyzing power A( $\vec d$ , π)X on the pion transverse momentum.

A design for a ΔE-E detector to investigate deuteron breakup in the Nuclotron-M internal target in a deuteron energy interval of 300–500 MeV is presented. The high-voltage power supply system of the PMT-63, which is based on the computer-controlled Wenzel Electronik module, is briefly described. A light-emitting diode (LED) monitoring system for the ΔE-E detector is considered. The results of testing the ΔE-E detector using cosmic muons and deuteron beams of the Nuclotron are presented.

The review of the recent results on spin effects in few nucleon systems obtained at LHEP-JINR are presented. The data on the deuteron analyzing powers in different reactions in the wide energy range demonstrate the sensitivity to the spin structure of the light nuclei. The future plans on the studies with polarized deuterons from new polarized ion source at Nuclotron will be reported.

Along with π0 and η mesons, a resonance structure in the invariant mass spectrum of two photons at M γγ = 360 ± 7 ± 9 MeV is observed in the reaction dC → γ + γ + X at momentum 2.75 GeV/c per nucleon. Estimates of its width and production cross section are Γ = 63.7 ± 17.8 MeV and σγγ = 98 ± 24 −67 +93 μb, respectively. The collected statistics amount to 2339 ± 340 events of 1.5 × 106 triggered interactions of a total number ∼1012 of dC-interactions. This resonance structure is not observed in pC collisions at the beam momentum 5.5 GeV/c. Possible mechanisms of this ABC-like effect are discussed.