Investigation of the angular dependence of the analyzing powers in the deuteron-proton elastic scattering at the nuclotron

New polarimeter based on the asymmetry measurement in dp-elastic scattering has been constructed at internal target at Nuclotron (JINR). The result on the deuteron analyzing powers A _y , A _yy and A _xx in the deuteron-proton (dp) elastic scattering at the energies of 880 and 2000 MeV are presented. They are compared with different theoretical approaches.     

Deuteron beam polarimetry at the nuclotron

The scheme of the deuteron beam polarization measurements at Nuclotron are presented. A deuteron beam polarimeter based on the spin-asymmetry measurements in the dp-elastic scattering at large angles in center-of-mass system has been constructed at the internal target station at the Nuclotron of JINR. This polarimeter is planned to use for the measurements of the vector and tensor components of deuteron beam polarizations at the energies 270–2000 MeV simultaneously. Details on the low energy polarimeters are also discussed.     

Detection equipment for investigating dp elastic scattering at internal target of nuclotron in the framework of DSS project

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.     

Measurement of the vector and tensor analyzing powers in dp elastic scattering at the energy of 880 MeV

The preliminary results on the angular distributions of the vector A _y and tensor A _yy , A _xx analyzing powers in dp elastic scattering at T _d = 880MeV are presented. A region of center-of-mass system angles from 60° to 140° is covered. The experimental data are compared with the preliminary calculations obtained within framework of different theoretical approaches. The experiment has been performed at the Internal Target Station at Nuclotron within the framework of the program on the study of light nuclei spin structure proposed at JINR (Russia) and RIBF (Japan).     

Experiments on the study of the deuteron-proton interactions at intermediate energies at Internal Target at Nuclotron

The experimental program on the study of deuteron-proton interaction at Internal Target at Nuclotron is discussed. Recent results obtained for dp-elastic scattering and dp-breakup reactions at intermediate energies are presented. The status of the DSS setup upgrade is reported.     

The cross-section in <Emphasis Type="Italic">dp</Emphasis>-elastic scattering at the energies of 500, 700 and 880 MeV obtained at the internal target station of Nuclotron

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 Ratio Rdp of the quasielastic nd → p(nn) to the elastic np → pn charge-exchange-process yields at the proton emitting angle θp,lab = 0° over 0.55–2.0 GeV neutron-beam energy region. Comparison of the results with the model-dependent calculations

Our new experimental results (see, e.g., Preprint JINR no. E1-2008-61 (Dubna, 2008)) on ratio R _dp of the quasielastic charge-exchange yield at the proton emitting angle θ _p,lab = 0° for the nd → p(nn) reaction to the elastic np → pn charge-exchange yield were presented. The measurements were carried out at the Nuclotron of the Veksler and Baldin Laboratory of High Energies of the JINR (Dubna) at the neutron-beam kinetic energies of 0.55, 0.8, 1.0, 1.2, 1.4, 1.8, and 2.0 GeV. In this paper the comparison of the experimental R _dp data with the obtained R _dp calculations within the impulse approximation by using the invariant-amplitude sets from the GW/VPI phase-shift analysis is made. The R _dp values calculated using the set of invariant amplitude data for the elastic np → pn charge exchange at θ _p,CM = 0°, agree with the experimental data. This confirmed the nd → p(nn) process yield at θ _p,CM = 0° is caused by the contribution of the spin-dependent part of the elastic np → pn charge-exchange reaction. Thus, it has been shown that the obtained experimental R _dp results can be used for the Delta-Sigma experimental program to reduce the total ambiguity in the extraction of the amplitude real parts. The text was submitted by the authors in English.     

Status of NICA complex at JINR

New scientific program is proposed at Joint Institute for Nuclear Research (JINR) in Dubna aimed a study of hot and dense baryonic matter in the wide energy region from 2 GeV/amu to √s _NN = 11 GeV, and investigation of nucleon spin structure with polarized protons and deuterons maximum energy in the c.m. 27 GeV (for protons). To realize this program the development of JINR accelerator facility in high energy physics has started. This facility is based on the existing superconducting synchrotron—Nuclotron. The program foresees both experiments at the beams extracted from the Nuclotron, and construction of ion collider—the Nuclotron-based Ion Collider fAcility (NICA).     

Research program of the NIS-GIBS project at JINR Nuclotron

The research program planned for extracted proton and relativistic nuclei beams of the JINR Nuclotron is briefly outlined in this talk. The program is to be realized with the NIS-GIBS spectrometer and consists of two parts. The first one is aimed to search for effects of nucleon polarized strangeness in production of φ and ω mesons in pp and np scattering. The latter one is devoted to the investigation of hydrogen hypernuclei isotopes.     

Measurements of the ratio Rdp of the quasi-elastic nd \rightarrow p(nn) to the elastic np \rightarrow pn charge-exchange process yields at zero proton emission angle over the 0.55-2.0 GeV neutron beam energy region

New experimental results on the ratio R_dp of the quasi-elastic charge-exchange yield at the outgoing proton angle $ \theta_{{p,{\rm Lab}}}^{}$ = 0^° for the nd $ \rightarrow$ p(nn) reaction to the elastic np $ \rightarrow$ pn charge-exchange yield are presented. The measurements were carried out at the Nuclotron of the Veksler and Baldin Laboratory of High Energies of the JINR (Dubna) at the neutron beam kinetic energies of 0.55, 0.8, 1.0, 1.2, 1.4, 1.8 and 2.0GeV. The intense neutron beam with small momentum spread was produced by break-up of deuterons which were accelerated and extracted to the experimental hall. In both reactions mentioned above the outgoing protons with the momenta p _p approximately equal to the neutron beam momentum p _{n, beam} were detected in the directions close to the direction of incident neutrons, i.e. in the vicinity of the scattering angle $ \theta_{{p,{\rm Lab}}}^{}$ = 0^° . Measured in the same data taking runs, the angular distributions of the charge-exchange reaction products were corrected for the well-known instrumental effects and averaged in the vicinity of the incident neutron beam direction. These corrected angular distributions for every of nd $ \rightarrow$ p(nn) and np $ \rightarrow$ pn charge-exchange processes were proportional to the differential cross-sections of the corresponding reactions. The data were accumulated by the Delta-Sigma set-up magnetic spectrometer with two sets of multiwire proportional chambers located upstream and downstream of the momentum analyzing magnet. Inelastic processes were considerably reduced by the additional detectors surrounding the hydrogen and deuterium targets. The time-of-flight system was applied to identify the detected particles. The new R_dp data are compared with the existing ones, which were obtained below 1GeV, and with the calculations which were made using the phenomenological NN amplitude sets.     

Nucleon–Deuteron Breakup Differential Cross Sections Derived from the Quark-Model NN Interaction

The nd and pd breakup differential cross sections for E _N ≤ 65 MeV are examined using the energy-independent quark-model nucleon–nucleon interaction fss2. The Coulomb effect is incorporated by the sharp cut-off Coulomb force, acting between quarks, without the phase-shift renormalization for the breakup amplitudes. Our model yields the results very similar to the meson-exchange potentials, including disagreement for some specific kinematical configurations. This includes the notorious space star anomaly of the nd and pd scattering at E _N  = 13 MeV. The KVI data for the breakup differential cross sections of E _d  = 130 MeV dp scattering are reasonably reproduced by taking the Coulomb cut-off radius ρ = 16 fm.     

GEANT4 simulation of dp non-mesonic breakup reaction at 300 and 500 MeV

GEANT4 simulations of the reaction dp → ppn, i.e. the dp non-mesonic breakup reaction, at 300 and 500 MeV of deuteron energy for different detector configurations are presented. Two threads made from polyethylene and carbon with the thickness of 10 μm are used as targets. The goal of the simulations is to find a method by means of which the signal from the dp non-mesonic breakup can be separated from the background that mainly comes from the carbon content of the CH₂ target. The obtained results will be used in the experimental spin program that will be realized in Nuclotron in Dubna. The aim of this experimental investigation is to contribute to the elucidation of the structure of the spin dependent parts of the nucleon-nucleon and three-nucleon forces acting in the dp non-mesonic breakup. The deuteron energies will be ranging from 300 up to 500 MeV.     

NICA at JINR: New prospects for exploration of quark-gluon matter

A new scientific program is proposed at the Joint Institute for Nuclear Research (JINR) in Dubna aimed at studies of hot and dense baryonic matter in the wide energy range from 2 GeV/u kinetic energy in fixed target experiments to $\sqrt {s_{NN} } = 4 - 11$ GeV/u in the collider mode. To realize this program the development of the JINR accelerator facility in high-energy physics (HEP) has been started. This facility is based on the existing superconducting synchrotron??the Nuclotron. The program foresees both experiments at the beams extracted from the Nuclotron, and the construction of a heavy-ion collider??the Nuclotron-based Ion Collider fAcility (NICA) which is designed to reach the required parameters with an average luminosity of L = 10²⁷ cm^?2 s^?1.     

Projects of Nuclotron modernization and Nuclotron-based ion collider facility (NICA) at JINR

One of the basic facilities at the Joint Institute for Nuclear Research (JINR) in Dubna is the 6 A GeV Nuclotron, which has replaced the old weak focusing 10-GeV proton accelerator Synchrophasotron. The first relativistic nuclear beams with the energy of 4.2 A GeV were obtained at the Synchrophasotron in 1971. Since that time, relativistic nuclear physics has been one of the main directions of the JINR research program. In the coming years, the new JINR flagship program assumes the experimental study of hot and dense strongly interacting QCD matter at the new JINR facility. This goal is proposed to be reached by (i) development of the existing Nuclotron accelerator facility as a basis for generation of intense beams over atomic mass range from protons to uranium and light polarized ions, (ii) design and construction of the Nuclotron-based heavy Ion Collider fAcility (NICA) with the maximum nucleon-nucleon center-of-mass collision energy of √s _NN = 9 GeV and averaged luminosity 10²⁷ cm⁻² s⁻¹, and (iii) design and construction of the Multipurpose Particle Detector (MPD) at intersecting beams. Realization of the project will lead to unique conditions for research activity of the world community. The NICA energy region is of major interest because the highest nuclear (baryonic) density under laboratory conditions can be reached there. Generation of intense polarized light nuclear beams aimed at investigation of polarization phenomena at the Nuclotron is foreseen. The text was submitted by the author in English.     

Relativistic deuterons: Their dynamics and structure in collisions with nucleons and nuclei

A wide range of problems associated with investigating the structure and dynamics of relativistic deuterons in (d,p) processes on protons and atomic nuclei are considered. Experimental data include the proton momentum distributions and tensor analyzing power of these reactions on various nuclei and at various energies measured in beams of unpolarized and polarized deuterons at the JINR synchrophasotron. The experimental results are interpreted with an emphasis on using the light-front dynamics, which is well-suited for analyzing the data in terms of the wave function. The application of this approach for analyzing the A(d,p)X reaction is shown to be convenient for obtaining new important information on the deuteron structure at small distances and describing adequately its behavior at relativistic energies. The difficulties arising in this approach are also indicated. The suggestions for setting up new experiments in the designed polarized deuterons beam at Nuclotron are made.     

The ratio R dp of the quasielastic nd → p(nn) to the elastic np → pn charge-exchange-process yields at the proton emitting angle θ p,lab = 0° over 0.55–2.0 GeV neutron beam energy region. Experimental results

New experimental results on ratio R _dp of the quasielastic charge-exchange yield at the outgoing proton angle θ _p,lab = 0° for the nd → p(nn) reaction to the elastic np → pn charge-exchange yield, are presented. The measurements were carried out at the Nuclotron of the Veksler and Baldin Laboratory of High Energies of the JINR (Dubna) at the neutron-beam kinetic energies of 0.55, 0.8, 1.0, 1.2, 1.4, 1.8, and 2.0 GeV. The intense neutron beam with small momentum spread was produced by breakup of deuterons which were accelerated and extracted to the experimental hall. In both reactions mentioned above the outgoing protons with the momenta p _p approximately equal to the neutron-beam momentum p _n,beam were detected in the directions close to the direction of incident neutrons, i.e., in the vicinity of the scattering angle θ _p,lab = 0°. Measured in the same data-taking runs, the angular distributions of the charge-exchange-reaction products were corrected for the well-known instrumental effects and averaged in the vicinity of the incident-neutron-beam direction. These corrected angular distributions for every of nd → p(nn) and np → pn charge-exchange processes were proportional to the differential cross sections of the corresponding reactions. The data were accumulated by Delta-Sigma setup magnetic spectrometer with two sets of multiwire proportional chambers located upstream and downstream of the momentum analyzing magnet. Inelastic processes were considerably reduced by the additional detectors surrounding the hydrogen and deuterium targets. The time-of-flight system was applied to identify the detected particles. The accumulated data treatment and analysis, as well as possible sources of the systematic errors are discussed. The text was submitted by the authors in English.     

Elastic backwardpd-scattering in Δ-resonance region

Contribution ofΔ-resonance mechanism to elastic backwardpd-scattering overT ₀ =0.5–0.8 GeV range of incident energy is analyzed. As distinct from [1–3], the parameters ofNN?NΔ amplitudes in the phenomenology of one-mesonπ- andρ-exchange are determined frompp→pnπ ⁺ reaction immediately in the kinematic region where the processpd→dp occurs. It has been found as a result that in the vicinity of the region whereΔ-isobar is present on-mass-shell, the coherent sum of the amplitudes ofΔ-resonance mechanism, relativistic one-nucleon exchange and single scattering predicts thepd→dp cross-section to be twice smaller than the experimental one and does not describe the tensor polarization oft ₂₀ deuteron. Possible causes of this discrepancy as well as the relation between the mechanisms ofpd→dp process and the data on reactions of quasi-elastic knock-out of fast deuterons by protons (p,pd) from light nuclei, are discussed.     

Measurements of the Cross Sections and A y for D(p, n) Inclusive Breakup Reaction at 170 MeV

The effects of three-nucleon force (3NF) has been actively studied by using the nucleon–deuteron (Nd) scattering states. The differential cross sections of the elastic Nd scattering at the energy below 150 MeV can be well reproduced by incorporating 3NF in the Faddeev calculation based on modern nucleon–nucleon (NN) interactions. On the other hand, the differential cross sections of Nd elastic and inelastic scatterings at 250 MeV show large discrepancies between the data and the Faddeev calculations with 3NF. It indicates the presence of the missing features of the three nucleon system at this energy region. For the systematic study about the energy dependence of this large discrepancies, we measured the differential cross sections and the vector analyzing power A _y for the ²H(p, n) inclusive breakup reaction at 170 MeV. The experiment was carried out at RCNP by detecting scattered neutrons by using the neutron detector NPOL3. The data was compared with the results of the Faddeev calculations with and without the 3NF.     

Global analysis of the strangeness vector and axial form factors of the nucleon and their uncertainties

We have studied the strangeness contribution to the elastic vector and axial form factors of the nucleon, using all available electroweak elastic scattering data sensitive to these contributions. Specifically, we combine ??p and $\bar{\nu} p$ elastic scattering cross sections from Brookhaven E734 with parity-violating asymmetries in elastic ep scattering, and quasi-elastic ed and e ⁴He scattering, observed in the SAMPLE, HAPPEx, G0 and PVA4 experiments. We are able not only to determine these form factors at individual values of momentum-transfer (Q ²), as has been done recently, but also to fit the Q ²-dependence of these form factors using simple functional forms. We present the results of these fits using existing data.     

Longitudinal dynamics of <Superscript>197</Superscript>Au<Superscript>32+</Superscript> and <Superscript>197</Superscript>Au<Superscript>79+</Superscript> ions in NICA injection chain

The main objective of the NICA project developed at the Joint Institute for Nuclear Research (JINR) is to conduct experimental studies with colliding heavy ion beams in an energy range of 1–4.5 GeV/nucleonucleon with luminosity on the level of 1 × 10²⁷ cm⁻² s⁻¹. In this paper the operation regime of the collider injection chain providing the bunch with experimentally desirable parameters at the output of the Nuclotron is considered for gold ions as an example.