arXiv subjects

R. A. Shindin

Publications and source records attributed to R. A. Shindin.

5 recordsLinked to original sources

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

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↗

arXiv2008

Separation of Flip and Non-Flip parst of Charge Exchange np->pn at energies Tn = 0.5 - 2.0 GeV

The new Delta-Sigma experimental data on the ratio $R_{dp}$ allowed separating the Flip and Non-Flip parts of the differential cross section of $np\to pn$ charge exchange process at the zero angle by the Dean formula. The PSA solutions for the $np\to np$ elastic scattering are transformed to the $np\to pn$ charge exchange representation using unitary transition, and good agreement is obtain.

hep-ex↗