M.C. Bouwhuis

Measurement of T20 in Elastic Electron-Deuteron Scattering

The authors report on a measurement of the tensor analyzing power T{sub 20} in elastic electron-deuteron scattering in the range of four-momentum transfer from 1.8 to 3.2 fm{sup {minus}1}. Electrons of 704 MeV were scattered from a polarized deuterium internal target. The tensor polarization of the deuterium nuclei was determined with an ion-extraction system, allowing an absolute measurement of T{sub 20}. The data are described well by a non-relativistic calculation that includes the effects of meson-exchange currents.

Performance of a Polarized Deuterium Internal Target in a Medium-Energy Electron Storage Ring.

Abstract A polarized deuterium target internal to a medium-energy electron storage ring is described in the context of spin-dependent (e,e′d) and (e,e′p) experiments. Tensor polarized deuterium was produced in an atomic beam source and injected into a storage cell target. A Breit-Rabi polarimeter was used to monitor the injected atomic beam polarization. An electrostatic ion-extraction system and a Wien filter were utilized to measure on-line the atomic fraction of the target gas (71 ± 2%) in the storage cell. A target thickness t ⋍ 2 × 10 13 2 H/cm 2 was achieved. The target tensor polarization was varied from P zz + = 0.49(3) to P zz − = −0.89(6) while keeping the vector polarization P z at zero. The luminosity was ∼ 2 × 10 31 e − · 2 H · cm −2 s −1 at a beam current of 120 mA. The performance was stable over a fiv running period. A large acceptance non-magnetic detector system was used for the electron-proton (deuteron) coincidence measurement. It is demonstrated that these techniques result in low backgrounds due to scattering from species other than the polarized target gas and allow for fast and flexible orientation of the target spin. Specific issues such as interfacing the experiment to the storage ring and monitoring the performance of the target system are discussed in detail.

Tensor Analyzing Powers for Quasielastic Electron Scattering from Deuterium

We report on a first measurement of tensor analyzing powers in quasi-elastic electron-deuteron scattering at an average three-momentum transfer of 1.7 fm{sup -1}. Data sensitive to the spin-dependent nucleon density in the deuteron were obtained for missing momenta up to 150 MeV/c with a tensor polarized {sup 2}H target internal to an electron storage ring. The data are well described by a calculation that includes the effects of final-state interaction, meson-exchange and isobar currents, and leading-order relativistic contributions.

Supersonic gas jets as internal targets at NIKHEF

Abstract We investigated a gas jet issued from a rectangular slit nozzle. Such jets can be made to dynamically converge by interacting with the residual, lower density, gas inside the accelerator vacuum vessel. Densities of up to few times 10 15 atoms cm −2 were achieved. We describe the experimental facility, the diagnostics used and present the result of our data analysis.

Spin-dependent electromagnetic response of few-body systems.

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 (Ay0) and longitudinal (A′z) asymmetries at Q ⋍ 2 fm−1. We outline the performance of the target and detectors.

Electron scattering at NIKHEF with polarized beam and targets

We present the Internal Target Facility of the NIKHEF 900 MeV polarized electron storage ring. We give some results which illustrate the presently unique opportunity offered by this facility to study the spin structure of the nucleon, 2-body and 3-body system by the measurement of spin-dependent electron scattering observables.

A large-acceptance detector system for electron scattering from polarized internal targets

Abstract The design and the performance of a non-magnetic detector setup for internal target physics at the NIKHEF electron-scattering facility is described. The detector setup, used in the first internal-target experiment at the AmPS ring, measures the spin dependence in the elastic and break-up reaction channels from tensor polarized deuterium. It has been established that the detector setup can operate adequately in an internal target environment at luminosities up to 10 32 e − atoms cm −2 s −1 . Results and measured resolutions are presented.

Measurement ofT20in Elastic Electron-Deuteron Scattering

The authors report on a measurement of the tensor analyzing power T{sub 20} in elastic electron-deuteron scattering in the range of four-momentum transfer from 1.8 to 3.2 fm{sup {minus}1}. Electrons of 704 MeV were scattered from a polarized deuterium internal target. The tensor polarization of the deuterium nuclei was determined with an ion-extraction system, allowing an absolute measurement of T{sub 20}. The data are described well by a non-relativistic calculation that includes the effects of meson-exchange currents.

Polarized deuterium internal target at AmPS (NIKHEF)

We describe the polarized deuterium target internal to the NIKHEF medium-energy electron storage ring. Tensor polarized deuterium was produced in an atomic beam source and injected into a storage cell target. A Breit-Rabi polarimeter was used to monitor the injected atomic beam intensity and polarization. An electrostatic ion-extraction system and a Wien filter were utilized to measure on-line the atomic fraction of the target gas in the storage cell. This device was supplemented with a tensor polarization analyzer using the neutron anisotropy of the 3H(d,n)α reaction at 60 keV. This method allows determining the density-averaged nuclear polarization of the target gas, independent of spatial and temporal variations. We address issues important for polarized hydrogen/deuterium internal targets, such as the effects of spin-exchange collisions and resonant transitions induced by the RF fields of the charged particle beam.

A Compton backscattering polarimeter for measuring longitudinal electron polarization

Compton backscattering polarimetry provides a fast measurement of the polarization of an electron beam in a storage ring. Since the method is nondestructive, the polarization of the electrons can be monitored during internal target experiments. At NIKHEF a Compton polarimeter has been constructed to measure the polarization of the longitudinally polarized electrons stored in the AmPS ring. First results obtained with the polarimeter, the first Compton polarimeter to measure the polarization of a stored longitudinally polarized electron beam, are presented in this paper.