N. Papadakis

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.

A Compton backscattering polarimeter for measuring longitudinal electron polarization

Abstract Compton backscattering polarimetry provides a fast and accurate method to measure the polarization of an electron beam in a storage ring. Since the method is non-destructive, the polarization of the electron beam can be monitored during internal target experiments. For this reason, a Compton polarimeter has been constructed at NIKHEF to measure the polarization of the longitudinally polarized electrons which can be stored in the AmPS ring. The design and results of the polarimeter, the first Compton polarimeter to measure the polarization of a stored longitudinally polarized electron beam directly, are presented in this paper.

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.

The polarized electron source at NIKHEF

An overview of the polarized electron source used at the NIKHEF accelerator facility is given. Since its first operation in September 1996 we have obtained currents in the source larger than 150 mA, and polarization degrees up to 88%. Approximately 350 hours have been dedicated to physics with a polarized 3He internal target. Using one InGaAsP photocathode, 2 μs long pulses were produced with a current of 2 mA in the local linac, with a polarization degree of 82.5%, at a repetition rate of 1 Hz. Source operations had to be interrupted about every eleventh day for approximately an hour for photocathode reactivation. A photocathode lifetime (1/e) of 180 hours has been achieved.

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.

The photocathode gun of the Polarized Electron Source at NIKHEF

A description is given of the 100 kV photocathode gun of the 400 kV Polarized Electron Source (PES) used for internal target physics on polarized light nuclei at the Amsterdam Pulse Stretcher (AmPS) storage ring. The gun provides 2 μs long pulses of polarized electrons with a current up to 50 mA, at a repetition rate of 1 Hz, and a polarization degree up to 85%. Using the pulsed power supply, no deterioration of the vacuum during gun operation has been observed. An operational lifetime (1/e), using an InGaAsP photocathode, of 180 hours has been measured. The injection efficiency of the polarized beam from PES into the linear Medium Energy Accelerator is measured to be ≈30%.

Proton knock‐out from tensor polarized deuterium

A status report is given on experiment 91‐12, which is the first internal target experiment performed at the internal target facility of NIKHEF. The aim of this experiment is to measure the asymmetry in the (e,e′p) reaction from a tensor polarized deuterium target with unpolarized electrons. An update on the experimental setup and results of an extensive set of test measurements are presented.