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A. N. Livanov

Publications and source records attributed to A. N. Livanov.

12 recordsLinked to original sources
arXiv2026

Nuclotron internal target polarimeter for the measurements of the deuteron and proton beam polarization

Studies of spin-dependent effects at the Nuclotron/NICA accelerator complex at JINR require precise measurements of the deuteron and proton beam polarization. The vector polarization of the deuteron beam was measured at the energies of 200, 500, 550, and 650 MeV/nucleon by a detection system of scintillation counters placed at the Nuclotron internal target. Considering the deuteron beam as a beam of weakly bound protons and neutrons, the asymmetries of scattering of protons from deuterons on polyethylene and carbon targets were determined. The polarization of the polarized proton beam accelerated for the first time at the Nuclotron up to 500 MeV was also measured.

physics.ins-det↗
arXiv2022

Deuteron analyzing powers $A_y$, $A_{yy}$ and $A_{xx}$ in dp-elastic scattering at large transverse momenta

The results on the the vector $A_y$, $A_{yy}$ and $A_{xx}$ analyzing powers in deuteron-proton elastic scattering at large scattering angles 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 the wide energy range demonstrate the sensitivity to the short-range spin structure of the isoscalar nucleon-nucleon correlations.

nucl-ex↗
arXiv2019

Measurement of neutron and proton analyzing powers on $C$, $CH$, $CH_2$ and $Cu$ targets in the momentum region 3-4.2 GeV/c

The analyzing powers for proton elastic scattering ($\vec p A\to pX$) and neutron charge exchange ($\vec n A\to p X$) reactions on nuclei have been measured on $ C$, $CH$, $CH_2$ and $Cu$ targets at incident neutron momenta 3.0 - 4.2 GeV/c by detecting one charged particle in forward direction. The polarized neutron measurements are the first of their kind. The experiment was performed using the Nuclotron accelerator in JINR Dubna, where polarized neutrons and protons were obtained from breakup of a polarized deuteron beam which has a maximum momentum of 13 GeV/c. The polarimeter ALPOM2 was used to obtain the analyzing power dependence on the transverse momentum of the final-state nucleon. These data have been used to estimate the figure of merit of a proposed experiment at Jefferson Laboratory to measure the recoiling neutron polarization in the quasi-elastic $^2H(\vec e,e'\vec n)$ reaction, which yields information on the charge and magnetic elastic form factors of the neutron.

nucl-ex↗
arXiv2018

Right sign of spin rotation operator

For the fermion transformation in the space all books of quantum mechanics propose to use the unitary operator $\widehat{U}_{\vec n}(φ)=\exp{(-i\frac\varphi2(\widehatσ\cdot\vec n))}$, where $φ$ is angle of rotation around the axis $\vec{n}$. But this operator turns the spin in inverse direction presenting the rotation to the left. The error of defining of $\widehat{U}_{\vec n}(φ)$ action is caused because the spin supposed as simple vector which is independent from $\widehatσ$-operator a priori. In this work it is shown that each fermion marked by number $i$ has own Pauli-vector $\widehatσ_i$ and both of them change together. If we suppose the global $\widehatσ$-operator and using the Bloch Sphere approach define for all fermions the common quantization axis $z$ the spin transformation will be the same: the right hand rotation around the axis $\vec{n}$ is performed by the operator $\widehat{U}^+_{\vec n}(φ)=\exp{(+i\frac\varphi2(\widehatσ\cdot\vec n))}$.

quant-ph↗
arXiv2017

Charge-exchange quasi-elastic process $nd\to p(nn)$ under $0^\circ$ in the frame of elastic $np\to np$ scattering to $180^\circ$

It is considered the problem of spin physics related with the difference of representation of the elastic interaction between the neutron and proton. In the first case the charge-exchange reaction $np\to pn$ under the angle $θ$ is supposed, in the second --- the simple elastic scattering of $np\to np$, when the neutron is going in opposite direction $π-θ$. The transition from one representation to another is provided by the Majorana operator. In the framework of impulse approximation it is twice calculated the quasi-elastic charge-exchange reaction of a neutron on a deuteron. In the frame of $nd\to p(nn)$ scattering of proton to the angle $θ$ it gives the well-known Dean formula. Using other representation $nd\to (nn)p$ as a neutron elastic scattering under the angle $π-θ$ (together with neutron-spectator in $nn$-pair) the alternative formula is presented.

nucl-th↗
arXiv2017

Measurement of the deuteron beam polarization at internal target at Nuclotron for DSS experiment

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.

physics.ins-det↗
arXiv2017

First results on the measurements of the proton beam polarization at internal target at Nuclotron

The spin program at NICA using SPD and MPD requires high intensity polarized proton beam with high value of the beam polarization. First results on the measurements of the proton beam polarization performed at internal target at Nuclotron are reported. The polarization of the proton beam provided by new source of polarized ions has been measured at 500 MeV using quasielastic proton-proton scattering and DSS setup at internal target. The obtained value of the vertical polarization of ~35 % is consistent with the calculations taking into account the current magnetic optics of the Nuclotron injection line.

physics.ins-det↗
arXiv2017

Interesting effect of the nd -> p(nn) reaction

The reaction nd -> p(nn) produce two slow neutrons in the final state instead of deuteron. In the first view we can take into account the binding energy e ~ 2.23 MeV but this approach can not explain all features which are observed in the momentum spectrum of the secondaries protons. We need to suppose that two slow neutrons in the final state form the intermediate system which has own distribution of internal Fermi momentum.

nucl-th↗
arXiv2012

Measurement of the vector and tensor analyzing powers for dp- elastic scattering at 880 MeV

The vector Ay and tensor analyzing powers Ayy and Axx for dp- elastic scattering were measured at Td = 880 MeV over the c.m. angular range from 60 to 140 degrees at the JINR Nuclotron. The data are compared with predictions of different theoretical models based on the use of nucleon-nucleon forces only. The observed discrepancies of the measured analyzing powers from the calculations require the consideration of additional mechanisms.

nucl-ex↗
arXiv2011

The light nuclei spin structure from hadronic channels at intermediate energies

The investigation of the d, 3H and 3He spin structure has been performed at the RIKEN(Japan) accelerator research facility and VBLHEP(JINR) using both polarized and unpolarized deuteron beams. The experimental results on the analyzing powers studies in dp- elastic scattering, d(d,3H)p and d(d,3He)n reactions are presented. The vector and tensor analyzing powers for dp-elastic scattering at 880 and 2000 MeV are obtained at the Nuclotron(VBLHEP). The result on the analyzing powers Ay, Ayy of the deuteron at 2000 MeV are compared with relativistic multiple scattering model calculations. The data on the tensor analyzing powers for the d(d,3H)p and d(d,3He)n reactions obtained at Ed = 200 and 270 MeV demonstrate the sensitivity to the 3H, 3He and deuteron spin structure. The essential disagreements between the experimental results and the theoretical calculations within the one-nucleon exchange model framework are observed. The wide experimental program on the study of the polarization effects in dp- elastic scattering, dp-nonmesonic breakup, d(d,3He)n, d(d,3H)p and d(3He,4He)p reactions using internal and extracted beam at Nuclotron is discussed.

nucl-ex↗
arXiv2010

The 270 MeV deuteron beam polarimeter at the Nuclotron Internal Target Station

A deuteron beam polarimeter has been constructed at the Internal Target Station at the Nuclotron of JINR. The polarimeter is based on spin-asymmetry measurements in the d-p elastic scattering at large angles and the deuteron kinetic energy of 270 MeV. It allows to measure vector and tensor components of the deuteron beam polarization simultaneously.

nucl-ex↗