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

doi:10.1016/0168-9002(93)90693-C

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

Volume 327, Issues 2–3, 1 April 1993, Pages 277-286

https://doi.org/10.1016/0168-9002(93)90693-C Get rights and content

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.

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The storage cell of the polarized H/D internal gas target of the HERMES experiment at HERA
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The storage cell of the internal, longitudinally polarized, atomic gas target of the HERMES experiment is presented. The polarized atoms of hydrogen or deuterium are accumulated in an open-ended thin walled storage cell through which the circulating electron or positron beam of the HERA accelerator passes. The target areal density is $10^{14} atoms/cm^{2}$ , two orders of magnitude larger than without the cell. The construction details of the cell are described and the cell's performance during HERMES run of 1997–2000 is discussed.
Internal polarized deuterium target with cryogenic atomic beam source
2002, Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
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.
Polarized hydrogen/deuterium atomic beam source for internal target experiments
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A high-brightness hydrogen/deuterium atomic beam source is presented. The apparatus, previously used in electron scattering experiments with tensor-polarized deuterium (Ferro-Luzzi et al., Phys. Rev. Lett. 77 (1996) 2630; van den Brand et al., Phys. Rev. Lett. 78 (1997) 1235; Zhou et al., Phys. Rev. Lett. 82 (1998) 687; Bouwhuis et al., Phys. Rev. Lett. 82 (1999) 3755), was configured as a source for internal target experiments to measure single- and double-polarization observables, with either polarized hydrogen or vector/tensor polarized deuterium. The atomic beam intensity was enhanced by a factor of ∼2.5 by optimizing the Stern–Gerlach focusing system using high tip-field $(∼1.5 T)$ rare-earth permanent magnets, and by increasing the pumping speed in the beam-formation chamber. Fluxes of $(5.9±0.2)×10^{16}^{1} H/s$ were measured in a $∅12 mm ×122 mm$ compression tube with its entrance at a distance of 27 cm from the last focusing element. The total output flux amounted to $(7.6±0.2)×10^{16}^{1} H/s$ .
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1998, Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
The HERMES experiment is investigating the spin structure of the proton and neutron via deep-inelastic scattering of polarized positrons from polarized nuclear targets. The polarized positrons are provided by the HERA positron storage ring at DESY, Hamburg, Germany. The targets are pure internal gas targets. Data acquisition began in 1995, utilizing a polarized ³He internal gas target to study the spin structure of the neutron. The target gas was polarized using the metastability-exchange optical-pumping technique and then injected into a cryogenically cooled target cell. The target was designed to operate with either longitudinal or transverse directions of polarization. Operating conditions included polarizations of up to 54% and target thicknesses of 1×10¹⁵ nucleons/cm². In this paper the HERMES polarized ³He internal gas target is described in detail.
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We report on the experimental program with polarized electrons and polarized few-body systems at the internal target facility of the NIKHEF electron storage ring.
With a polarized deuterium internal target, absolute measurements of unprecedented accuracy have been performed for the analyzing powers T₂₀ and T₂₂ in elastic electron-deuteron scattering at transferred four-momenta 1.1 < Q < 2.8 fm⁻¹. Results for a first measurement of the tensor analyzing power in quasi-elastic scattering are also presented. These data provide new constraints for descriptions of the deuteron spin structure and for reaction mechanism effects.
Quasi-elastic electron scattering from polarized ³He may provide precise information on the S′ and the D-wave parts of the ³He ground-state wave function, the neutron form factors, and the role of spin-dependent reaction mechanism effects. We have started an experimental program at NIKHEF where polarized ³He and polarized electrons are used, in combination with large acceptance electron and hadron detectors. Data were taken for the transverse (A_y⁰) and longitudinal (A′_z) asymmetries at $Q ⋍ 2 fm^{−1}$ . We outline the performance of the target and detectors.
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1998, Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
An ion-extraction polarimeter has been developed for internal target experiments in storage rings. Here, we report on the application of such a device for a tensor polarized deuterium gas target internal to a medium-energy electron storage ring. Ions, produced by the stored electron beam, were extracted from a storage cell using electrostatic lenses and a spherical deflector, transported to a mass-analyzer, and subsequently to a ³H( $d$ ,n)α tensor polarization analyzer. The method allows determining the density-averaged nuclear polarization of the target gas, independent of spatial and temporal variations. We discuss in detail the systematic uncertainties (< 5%) associated with this technique.

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¹: Present address: Dept. of Physics and Astronomy, Rutgers University, Piscataway, NJ 08855, USA.

²: Present address: Dept. of Physics, University of Colorado, Boulder, CO 80309, USA.

³: Present address: Dept. of Physics, Renssalaer Polytechnic Institute, Troy, NY 12180, USA.

⁴: Present address: Tomsk Institute of Spectroscopy, Tomsk, Russian Federation.

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

Abstract

Phys. Lett.

Nucl. Instr. and Meth.

Nucl. Instr. and Meth.

Doctor's thesis

diploma thesis

Nucl. Instr. and Meth.

Phys. Rev.

Pis'ma Zh. Eksp. Teor. Fiz.

JETP Lett.

Phys. Lett.

Nucl. Instr. and Meth.