Deuteron Tensor Polarization Research Articles

Effect of T-Invariance Violation in Scattering of Polarized 3He Nuclei on Tensor-Polarized Deuterons

In the interaction of a transversely polarized nuclear beam with a tensor-polarized deuteron target, a nonzero value of the component of the total cross section corresponding to this combination of polarizations is an unambiguous signal ofT-invariance violation whileP-parity is preserved. The method developed earlier for calculating this component of the total cross section forpdscattering based on the Glauber theory has been generalized by us to the case of3Hedscattering, and its energy dependence in the range of beam energies 0.1–1 GeV/nucleon has been calculated. It is found that in3Hedcollisions, in contrast topdscattering, the contribution of only one type ofT-violating nucleon-nucleon forces dominates, which is essential for extraction of the unknown constant of this interaction from the corresponding data.

Effect of T-Invariance Violation in Scattering of Polarized 3He Nuclei on Tensor-Polarized Deuterons

Effect of T-Invariance Violation in Scattering of Polarized 3He Nuclei on Tensor-Polarized Deuterons

New approach to search for parity-even and parity-odd time-reversal violation beyond the Standard Model in a storage ring

Time-reversal breaking and parity-conserving millistrong interactions, suggested in 1965, still remain a viable mechanism of CP-violation beyond the Standard Model. One of its possible manifestations is the T-odd asymmetry in the transmission of tensor-polarized deuterons through a vector-polarized hydrogen gas target. Upon the rotation of the deuteron polarization from the vertical direction into the ring plane, the T-odd asymmetries, odd against the reversal of the proton polarization in the target, will continuously oscillate with first or second harmonics of the spin precession frequency. The Fourier analysis of the oscillating T-odd asymmetries allows for an easy separation from background persistent in conventional experiments employing static vector and tensor polarizations.

The possibility of studying polarization observables in reactions of the production of pions by polarized beams of protons and deuterons at the JINR LHEP

Along with studying the properties of strongly excited hadronic matter at high densities of the baryon charge, studies with polarized protons and deuterons are planned at the LHEP accelerator complex (see [1–3]). The purpose of this note is to analyze the possibility of obtaining new experimental data, based on the presence of beams of polarized protons and deuterons. In addition, the use of extracted beams of tensor-polarized deuterons to study the structure of the deuteron at small internucleon distances is discussed.

Measurement of a double spin asymmetry in the photoproduction of $\pi^{-}$ π - -mesons on deuterons

The paper presents results of a double polarization experiment to extract an asymmetry of the $\pi^{-}$ -meson photoproduction on a tensor-polarized deuteron by a linearly polarized photon. The energy of photons lies in the range (300-700) MeV. The measurements were performed on the internal tensor-polarized deuterium target in the VEPP-3 electron-positron storage ring for the electron beam energy equal to 2 GeV. In the experiment, two protons and a scattered electron were detected in coincidence. The results of the measurement are compared with theoretical predictions made in the framework of impulse approximation, taking into account the $\pi N$ and NN-rescattering in the final state.

Measurement of the Asymmetry of Photoproduction of π– Mesons on Linearly Polarized Deuterons by Linearly Polarized Photons

The first results of a double polarization experiment to extract the asymmetry of the reaction of photoproduction of a π- meson by a linearly polarized photon on a tensor-polarized deuteron in the energy range of the virtual photon (300–700 MeV) are presented. The measurements were performed on an internal tensor-polarized deuterium target in the VEPP-3 electron-positron storage ring for the electron beam energy equal to 2 GeV. The experiment employed the method of recording two protons and the scattered electron in coincidence. The obtained measurement results are compared with the theoretical predictions obtained in the momentum approximation with allowance for πN and NN rescattering in the final state.

Theoretical estimate on tensor-polarization asymmetry in proton-deuteron Drell-Yan process

Tensor-polarized parton distribution functions are new quantities in spin-one hadrons such as the deuteron, and they could probe new quark-gluon dynamics in hadron and nuclear physics. In charged-lepton deep inelastic scattering (DIS), they are studied by the twist-two structure functions $b_1$ and $b_2$. The HERMES collaboration found unexpectedly large $b_1$ values than a naive theoretical expectation based on the standard deuteron model. The situation should be significantly improved in the near future by an approved experiment to measure $b_1$ at JLab (Thomas Jefferson National Accelerator Facility). There is also an interesting indication in the HERMES result that finite antiquark tensor polarization exists. It could play an important role in solving a mechanism on tensor structure in the quark-gluon level. The tensor-polarized antiquark distributions are not easily determined from the charged-lepton DIS; however, they can be measured in a proton-deuteron Drell-Yan process with a tensor-polarized deuteron target. In this article, we estimate the tensor-polarization asymmetry for a possible Fermilab Main-Injector experiment by using optimum tensor-polarized PDFs to explain the HERMES measurement. We find that the asymmetry is typically a few percent. If it is measured, it could probe new hadron physics, and such studies could create an interesting field of high-energy spin physics. In addition, we find that a significant tensor-polarized gluon distribution should exist due to $Q^2$ evolution, even if it were zero at a low $Q^2$ scale. The tensor-polarized gluon distribution has never been observed, so that it is an interesting future project.

New analytical forms of wave function in coordinate space and tensor polarization of deuteron

The coefficients of new analytical forms for the deuteron wave function (DWF) in coordinate space for NijmI, NijmII, Nijm93, Reid93 and Argonne v18 potentials have been numerically calculated. The obtained wave functions do not contain any superfluous knots. The designed parameters of the deuteron are in good agreement with the experimental and theoretical data. The tensor polarization [Formula: see text] calculated based on the wave functions is proportionate to the earlier published results.

Progress on nuclear modifications of structure functions

We report progress on nuclear structure functions, especially on their nuclear modifications and a new tensor structure function for the deuteron. To understand nuclear structure functions is an important step toward describing nuclei and QCD matters from low to high densities and from low to high energies in terms of fundamental quark and gluon degrees of freedom beyond conventional hadron and nuclear physics. It is also practically important for understanding new phenomena in high-energy heavy-ion collisions at RHIC and LHC. Furthermore, since systematic errors of current neutrino-oscillation experiments are dominated by uncertainties of neutrino-nucleus interactions, such studies are valuable for finding new physics beyond current framework. Next, a new tensor-polarized structure function $b_1$ is discussed for the deuteron. There was a measurement by HERMES; however, its data are inconsistent with the conventional convolution estimate based on the standard deuteron model with D-state admixture. This fact suggests that a new hadronic phenomenon should exist in the tensor-polarized deuteron at high energies, and it will be experimentally investigated at JLab from the end of 2010's.

Measuring tensor analyzing power component T 20 of the coherent photoproduction of a neutral pion on a tensor-polarized deuteron in the VEPP-3 storage ring

An experiment to measure tensor analyzing power component T 20 of the coherent photoproduction reaction of a neutral pion on a tensor-polarized deuterium target \(\left( {\gamma \vec d \to d\pi ^0 } \right)\) is described. Measurements are made in two kinematic ranges: photon energy E γ = 200–500 MeV and neutral pion escape angle \(\Theta _{\pi ^0 }^{cm} = 100^ \circ - 140^ \circ\), E γ = 300–600 MeV, and \(\Theta _{\pi ^0 }^{cm} = 40^ \circ - 70^ \circ\). A hyperfine internal gas polarized target is used in the experiment. Detectors of neutral pions and deuterons register these particles when they coincide. The degree of target polarization and experimental luminosity are measured via the registration of elastic electron scattering on a deuteron at a low momentum of transfer. The preliminary experimental results are compared to certain theoretical predictions.

Inclusive and Exclusive Scatterings from Tensor Polarized Deuteron

The possibility of using a tensor polarized deuteron target in electroproduction reactions creates new opportunities for studying different phenomena related to the short-range hadronic and nuclear physics. The use of the tensor polarized deuteron allows us to isolate smaller than average inter-nucleon distances for the bound two-nucleon system. In this report we consider several high Q2 reactions which are particularly sensitive to the short-range two- nucleon configurations in the deuteron. One is the relativistic dynamics of electron-bound- nucleon scattering, which can be studied in both inclusive and exclusive reactions, and the other is the strong final state interaction in close proximity of two nucleons that can be used as a sensitive probe for color-transparency phenomena.

Investigation into tensor polarization enhancement of solid polarized targets

A discussion of tensor polarization of solid targets produced by Dynamic Nuclear Polarization and Dynamic Nuclear Orientation in the use of nuclear physics experiments is presented. Techniques in the deuteron tensor polarization enhancement and enhanced tensor polarization measurement uncertainty are also discussed in the interest and preparation of future experiments.

Tensor polarization of deuterons passing through matter

It is shown that the magnitude of tensor polarization of the deuteron beam, which arises owing to the spin dichroism effect, depends appreciably on the angular width of the detector that registers the deuterons transmitted through the target. Even when the angular width of the detector is much smaller than the mean square angle of multiple Coulomb scattering, the beam’s tensor polarization depends noticeably on rescattering. When the angular width of the detector is much larger than the mean square angle of multiple Coulomb scattering (as well as than the characteristic angle of elastic nuclear scattering), tensor polarization is determined only by the total reaction cross sections for deuteron–nucleus interaction, and elastic scattering processes make no contribution to tensor polarization.

On the possibility to measure the imaginary part of the spin-dependent amplitude of zero-angle coherent elastic scattering in a spin-filter experiment with an unpolarized proton beam interacting with a polarized deuterium target

As deuterons pass through an unpolarized target, there appear the phenomena of spin rotation (oscillation) and spin dichroism of deuterons; both phenomena are the manifestation of the deuteron birefringence effect. The magnitude of the effect is determined by the refractive index of deuterons in matter, which depends on the spin-dependent part d1 of the amplitude of zero-angle coherent elastic scattering of the deuteron by the nucleus. Spin dichroism is determined by the imaginary part of this amplitude, and in view of the optical theorem, by the total scattering cross-section, which is different for different spin states of the deuteron. The phenomenon of spin dichroism of deuterons results in the fact that after passing through the target, the initially unpolarized deuteron beam acquires tensor polarization proportional to the difference in the total cross-sections of scattering of deuterons with different spin states by the nucleus. The stated difference was first measured for deuterons with energies up to 20 MeV, where the phenomenon of deuteron spin dichroism was experimentally revealed, and the deuteron tensor polarization was measured. The phenomenon of spin dichroism, i.e., the production of tensor polarization was also observed at high deuteron energy. In the present report we discuss the possibility that the imaginary part of the amplitude d1 of deuteron scattering by the proton may be determined experimentally by measuring the rate of the decrease in the intensity of an unpolarized proton beam in a storage ring as the beam passes through a tensor-polarized deuterium target.

Measurement of tensor polarization of deuterons from 3He → d + p breakup at internal momenta up to 0.4 GeV/c

The tensor polarization (ρ20) of deuterons emitted in the p(3He,d)X reaction at 0° in the lab. system was measured at the Saturne National Laboratory in Saclay, using the SPES-4 spectrometer with the HYPOM polarimeter in the area of its focal plane. The momentum of the detected deuterons was kept fixed at 3.77 GeV/c, while the momentum of the 3He beam was varied from 4.60 to 5.66 GeV/c, thus providing a range of internal momenta k of the deuteron inside the 3He from 0 up to 0.4 GeV/c. The obtained data are compared with the theoretical predictions.

Experiments with internal targets at the VEPP-3 electron storage ring

An overview of the recently completed, current, and planned experiments with internal targets at the VEPP-3 electron-positron storage ring in Novosibirsk is given. The results of the experiment to separately measure the deuteron form factors in elastic ed scattering in the range of momentum transfer Q 2 = 8−15 fm−2 are provided. The results of measuring the tensor analyzing power components of the tensor-polarized deuteron photodisintegration reaction in the range of γ-quantum energies E γ = 25−600 MeV are presented. The tensor analyzing powers of the coherent photoproduction of a neutral pion on a tensor-polarized deuteron have been measured for the first time. The almost-real photon tagging system being created is discussed. The status of the experiment under way to determine the contribution of two-photon exchange to the elastic ep scattering cross section is described.

Production of a Beam of Tensor-Polarized Deuterons Using a Carbon Target

An initially unpolarized beam of deuterons is found to acquire tensor polarization after traversing a foil of spin-zero target nuclei. The effect, called nuclear spin dichroism, has been predicted theoretically, albeit resulting in small values of p(zz) of the order of 0.01 for energies around 10 MeV. The experiment was carried out at the Köln tandem accelerator using carbon targets bombarded by deuterons. The observed polarization is as large as p(zz)=-0.28±0.03 for a beam of 14.8 MeV and a 129 mg/cm2 target. The results allow one to produce tensor-polarized deuterons with p(zz) around -0.30 (or +0.25) from an initially unpolarized beam using a carbon target of appropriate thickness.

Potential for measurement of the tensor magnetic polarizability of the deuteron in storage ring experiments

General formulas describing deuteron spin dynamics in storage rings with allowance for the tensor electric and magnetic polarizabilities are derived. It is found that an initially tensor-polarized deuteron beam can acquire a final horizontal vector polarization of the order of 1%. This effect allows one to measure the tensor magnetic polarizability of the deuteron in storage ring experiments. We also confirm an existence of the effect found by Baryshevsky and Gurinovich, hep-ph/0506135 and Baryshevsky, hep-ph/0510158; hep-ph/0603191 that the tensor magnetic polarizability of the deuteron causes the spin rotation with two frequencies and experiences beating for polarized deuteron beams in storage rings.

Deuteron tensor polarization componentT20(Q2)as a crucial test for deuteron wave functions

The deuteron tensor polarization component ${T}_{20}({Q}^{2})$ is calculated by the relativistic Hamiltonian dynamics approach. It is shown that in the range of momentum transfers available with current experiments, relativistic effects, meson exchange currents, and the choice of nucleon electromagnetic form factors almost do not influence the value of ${T}_{20}({Q}^{2})$. However, this value depends strongly on the actual form of the deuteron wave function, that is, on the model of the $\mathit{NN}$ interaction in the deuteron. So the existing data for ${T}_{20}({Q}^{2})$ provide a crucial test for deuteron wave functions.

Polarized D [formula omitted] beams at the cooler synchrotron COSY/Jülich

The polarized ion source at the COSY facility in the research center Jülich, Germany, delivered for first experiments polarized deuterons. Some of the developments for the delivery of vector and tensor-polarized deuterons are presented. For polarized protons injected into COSY a new record for polarization of 0.914 ± 0.022 was achieved. Five different states of deuteron beams with up to 0.764 ± 0.036 vector polarization were delivered for an experiment studying spin manipulation in synchrotrons.