C. E. Jones

Silane coatings for laser-driven polarized hydrogen sources and targets

It is necessary to use special coatings on the surfaces of volumes containing polarized atoms in order to minimize depolarizing spin interactions during wall collisions. We are studying coatings of organosilicon compounds that preserve hydrogen and potassium polarizations and prevent molecular recombination of hydrogen during wall collisions in a laser-driven polarized hydrogen source. Continuing problems with coatings for these sources has been the reproducibility of high-quality surfaces and reliable assessment of surface quality before installation of coated parts in the laser-driven source. We have used an atomic force microscope to scan surfaces coated with different organosilicon compounds with the goal of assessing surface quality and determining a method of preparing reproducible surfaces that do not degrade with time. Here we show AFM scans of the different coatings, discuss the quality of coatings made with different chemicals and application procedures, and present the results of coating stability tests as a function of temperature and exposure to potassium. We find that a simple organosilicon afterwash gives a significantly improved surface.

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.

Laser‐driven polarized targets of hydrogen and deuterium

An optical pumping technique used in a laser‐driven source of polarized hydrogen or deuterium is described and measurements of the achievable polarization as a function of flow for both hydrogen and deuterium are presented. Ongoing tests of the feasibility of using a laser‐driven polarized deuterium source coupled to a storage cell as a polarized internal target, including direct measurements of the nuclear polarization, are discussed.

Status of the T20 Experiment at VEPP-3

Using a gaseous polarized deuterium and the 2 GeV electron beam at 2 GeV beam energy the tensor analyzing power, T20, for the NN potential will be measured with the elastic d↘(e,e) reaction at VEPP‐3, Novosibirsk. A description and progress report of the experiment is given. (AIP)

Electron scattering from polarized deuterium at VEPP-3

The status, results, and future plans for the experiment measuring the tensor analyzing power of the deuteron using a tensor‐polarized internal target at the VEPP‐3 electron storage ring in Novosibirsk are presented.

Measurement of the asymmetry in the electro-disintegration of tensor polarized deuterons at the Novosibirsk VEPP-3 ring

A series of experiments with an internal tensor polarized deuterium target in the 2 GeV VEPP‐3 electron storage ring in Novosibirsk is being performed. This paper describes the first results for a measurement of the tensor asymmetry in the quasi‐elastic (e,e′p) reaction. The found results are compared to a non‐relativistic calculation by Arenhovel and Leidemann, including meson‐exchange currents, isobar admixtures, and final‐state interactions.