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The ultra-thin gas targets used in storage ring internal target experiments allow low energy, heavy nuclei to emerge from the target region. A detector capable of analyzing these nuclei provides unique access to many nuclear reactions. We report here the first use of such a detector in conjunction with a polarized 3 He internal target and a polarized electron beam. The results of using the detector as a luminosity monitor and as a polarimeter to measure the product of beam and target polarizations are presented. The ability to study coherent pion production via the reactions 3 He → ( e → , e ′ 3 He )π 0 and 3 He → ( e → , e ′ 3 H )π + is shown along with the ability of the detector to unambiguously separate the two- and three-body breakup channels of the reaction 3 He → ( e → , e ′p) .

We report on the first measurement of spin-correlation parameters in quasifree electron scattering from vector-polarized deuterium. Polarized electrons were injected into an electron storage ring at a beam energy of 720 MeV. A Siberian snake was employed to preserve longitudinal polarization at the interaction point. Vector-polarized deuterium was produced by an atomic beam source and injected into an open-ended cylindrical cell, internal to the electron storage ring. The spin correlation parameter $A^V_{ed}$ was measured for the reaction $^2 \vec{\rm H}(\vec e,e^\prime n)p$ at a four-momentum transfer squared of 0.21~(GeV/$c$)$^2$ from which a value for the charge form factor of the neutron was extracted.

We report on the first measurement of spin-correlation parameters in quasifree electron scattering from vector-polarized deuterium. Polarized electrons were injected into an electron storage ring at a beam energy of 720 MeV. A Siberian snake was employed to preserve longitudinal polarization at the interaction point. Vector-polarized deuterium was produced by an atomic beam source and injected into an open-ended cylindrical cell, internal to the electron storage ring. The spin correlation parameter A[sup V] [sub ed] was measured for the reaction [sup 2] H [rvec e] ([rvec e], e [prime] n) p at a four-momentum transfer squared of 0.21 (GeV/c)[sup 2] from which a value for the charge form factor of the neutron was extracted. [copyright] [ital 1999] [ital The American Physical Society]

Sensitivity to the quadrupole transition form factors (C2 and E2) of the N-Δ excitation can be obtained by measuring double-polarization electromagnetic observables in the Δ-region. Such measurements have been carried out with the internal target facility at NIKHEF. Radiative corrections are an important ingredient of the data interpretation. They need to be evaluated carefully, taking into account their spin-dependence, in order to compare the data to theoretical models of pion electroproduction. From these comparisons the E2/M1 and C2/M1 ratios can be extracted.

We report on the results of studies of the longitudinal electron polarization in the AmPS storage ring at NIKHEF. The ring was operated using a partial Siberian snake at the first magic energy, and a full Siberian snake between 440 MeV and 720 MeV. We have investigated the effect of high beam currents in the ring, and found that some of the electron polarization is lost if the beam current becomes larger than ≈120 mA.

Quasi-elastic electron scattering 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. An experiment is being performed at the AmPS storage ring at NIKHEF (Amsterdam, the Netherlands), where polarized electrons (up to 900 MeV) are used in combination with large acceptance electron and hadron detectors. Preliminary results from data at four-momentum transfer squared Q2=0.15 GeV2 are presented.

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.

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.