D.K. Toporkov

Internal polarized deuterium target with cryogenic atomic beam source

Abstract Description of the polarized deuterium gas target used at the VEPP-3 electron storage ring for experiments on elastic and inelastic ed scattering is given. Superconducting sextupole magnets with the pole tip magnetic field up to 4.8 T are used in atomic beam source (ABS) to focus atoms. The flux of polarized atoms injected into the storage cell was measured to be 8.2×10 16 at / s for deuterium and 7.9×10 16 at / s for hydrogen. The measured target thickness 8×10 13 at / cm 2 is consistent with the thickness calculated from the measured beam intensity. The effective tensor polarization of the deuterium target during the experiment was found to be P zz =0.397. Further improvements of the target and possible limitation of the beam intensity from ABS are discussed.

Measurement of tensor analyzing powers in deuteron photodisintegration

A new accurate measurement of the tensor analyzing powers T20, T21, and T22 in deuteron photodisintegration has been performed. Wide-aperture nonmagnetic detectors allowed broad kinematic coverage in a single set up: E(gamma)=25 to 600 MeV, and theta(p)(cm)=24 degrees to 48 degrees and 70 degrees to 102 degrees . The new data provide a significant improvement over the few existing measurements. The angular dependency of the tensor asymmetries in deuteron photodisintegration is extracted for the first time.

A polarized gas internal target using a storage cell in an electron storage ring

Abstract The first experiment using a storage cell to increase the thickness of an internal polarized gas target in an electron beam storage ring was performed at the VEPP-3 facility. We describe the storage cell technique as applied in this measurement of elastic and inelastic electron scattering from tensor polarized deuterium. An analysis of electron-beam-induced depolarization of the target was performed and experimental tests were carried out which verify the effect. Other effects causing depolarization of the target are discussed as well as the means by which they are overcome. The effective p zz of the target, shown to be stable over 8 months, was 0.57±0.05; the total target thickness was increased over that of a jet target by a factor of fifteen.

Laser-driven source of spin-polarized atomic hydrogen and deuterium

Abstract A laser-driven source of spin-polarized hydrogen (H) and deuterium (D) that relies on the technique of optical pumping spin exchange has been constructed. In this source, H or D atoms and potassium atoms flow continuously through a drifilm-coated spin-exchange cell where potassium atoms are optically pumped with circularly-polarized laser light in a high magnetic field. The H or D atoms become polarized through spin-exchange collisions with polarized potassium atoms. High electron polarization ( ≈ 80%) has been measured for H and D atoms at flow rates ≈ 2 × 1017 atoms/s. Lower polarization values are measured for flow rates exceeding 1 × 1018 atoms/s. In this paper, we describe the performance of the laser-driven source as a function of H and D atomic flow rate, magnetic field strength, alkali density and pump-laser power. Polarization measurements as a function of flow rate and magnetic field suggest that, despite a high magnetic field, atoms within the optical-pumping spin-exchange apparatus evolve to spin-temperature equilibrium which results in direct polarization of the H and D nuclei.

Intense polarized atomic deuteron source

Abstract An intense polarized deuteron gas jet, to be used as a target in an electron storage ring, is described. With a gas flow of 0.3 1 Torr/s through a nozzle, the flux of polarized atoms from a separation magnet is Q = 1.5 × 10 16 atoms/s. At a distance of 45 cm from the magnet the jet width, at half-height, is 6 mm and the target thickness t = 2 × 10 11 atoms/cm 2 . The degree of tensor polarization is P zz = −0.75 ± 0.10 for the 3 → 5 transition and P zz = 0.80 ± 10 for the 2 → 6 transition.

An active storage cell for a polarized gas internal target

Abstract The first experiment using an active storage cell for polarized atoms to increase the target thickness in an electron storage ring has been performed at the VEPP-3 facility. A clam-shell storage cell, which is opened while injecting electrons into the storage ring and closed during operation, was used to increase the target thickness viewed by the detector system. The average tensor polarization of the target was found to be p zz = 0.59 ± 0.14 and the figure of merit was increased by more than a factor of thirty in comparison with a direct jet thickness. The measured target thickness and polarization are in a good agreement with the expected values.

Basic Limitation On Polarized Atomic Beam Intensity

Analysis of the beam intensities from the atomic beam sources (ABS) are reviewed. This analysis shows that the intensity of the beams is saturated in the range of 1017 at/sec. The highest intensity of the polarized hydrogen beam obtained in the RHIC ABS and was found to be 1.2*1017 at/sec. Some possible reasons for the atomic beam intensity limitation such as beam formation model, intra beam scattering, background vacuum conditions, presence of the skimmers etc. are discussed. Some additional measurements are suggested to provide more complete understanding of the atomic beam formation and possible beam intensity improvement.

Application of internal gas target for beam polarization measurement in the electron storage ring

First results on polarization measurement are presented. More sophisticated scheme of polarimeter is proposed. It is expected that the accuracy of the measurement of polarization of the circulated electron beam of about 20% will be achieved during 8 minutes of operation of this Moller polarimeter. The work was supported by Russian Foundation for Basic Researches, grants 98-02-17949 and 98-02-17993, INTAS, grant 96-0424 and State Scientific and Technical Programm (Nuclear Physics).

Experiments with polarized deuterium target at VEPP‐3 storage ring: Status and perspective

A status of the internal polarized deuterium target experiment at VEPP‐3 storage ring at 2 GeV electron energy is presented. A value of T20 at q=3.7 fm−1 was obtained by using an active storage cell in conjunction with an atomic beam source. Substantial progress is expected by introducing the high‐density laser‐driven target.

Measurement of analyzing power T20 in elastic electron-deuteron scattering in the momentum transfer range of 0.3–0.8 (GeV/c)2

The results on the measurement of the analyzing power component T20 in elastic ed scattering are presented. An internal storage cell target technique was used in the VEPP-3 electron ring in Novosibirsk for this measurement. The measurement has been performed in the range of momentum transfer poorly investigated but important from theoretical point of view because of the node of the monopole charge form factor of the deuteron. The comparison of the other experimental data and some theories are discussed.