Measurement of the electric form factor of the neutron at low momentum transfers using a vector polarized deuterium gas target at BLAST

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2005.Includes bibliographical references (p. 207-217).Elastic form factors are fundamental quantities that characterize the electromagnetic structure of the nucleon. High precision measurements of these quantities are essential in understanding the structure of hadronic matter. Although the proton elastic form factors are well known, knowledge of the neutron form factors has been limited due to the lack of pure neutron targets. Few nucleon targets, deuterium in particular, are typically used to study the electromagnetic structure of the neutron. Cross section measurements are not sufficient for high precision determination of the electric form factor of the neutron, ..., due to its small value. Recently, experiments using polarization observables which are proportional to the product of the electric and magnetic form factors of the neutron have been used instead. Such measurements require highly polarized electron beams and either a vector polarized neutron target (typically ²H) or else a neutron final state polarimeter. The Bates Large Acceptance Spectrometer Toroid (BLAST) provides a unique opportunity to measure! the shape of the neutron electric form factor at low momentum transfers. BLAST combines a high duty-factor polarized electron beam in the South Hall Ring (SHR), an Atomic Beam Source (ABS) target of highly polarized deuterium atoms and a large acceptance detector. This work reports the results of measurements of the neutron electric form factor using the ... reaction at five 4-momentum transfer squared, Q², points of 0.14, 0.20, 0.29, 0.38 and 0.50 (GeV/c)² using data taken in 2004. The experimental setup is discussed in detail and the results for ... are presented and discussed in the context of various theoretical predictions.(cont.) A fit to the world's data including new BLAST data determines ... to ... over 0 < Q² < 1 ((GeV/c)². The best fit includes contributions from a low Q² bump and a smooth dipole term.by Vitaliy Ziskin.Ph.D

Measurement of the Vector and Tensor Asymmetries at Large Missing Momentum in Quasielastic ([→ over e],e′p) Electron Scattering from Deuterium

We report the measurement of the beam-vector and tensor asymmetries A[subscript ed][superscript V] and A[subscript d][superscript T] in quasielastic ([→ over e],e′p) electrodisintegration of the deuteron at the MIT-Bates Linear Accelerator Center up to missing momentum of 500  MeV/c. Data were collected simultaneously over a momentum transfer range 0.1<Q[superscript 2]<0.5  (GeV/c)[superscript 2] with the Bates Large Acceptance Spectrometer Toroid using an internal deuterium gas target polarized sequentially in both vector and tensor states. The data are compared with calculations. The beam-vector asymmetry A[subscript ed][superscript V] is found to be directly sensitive to the D-wave component of the deuteron and has a zero crossing at a missing momentum of about 320  MeV/c, as predicted. The tensor asymmetry A[subscript d][superscript T] at large missing momentum is found to be dominated by the influence of the tensor force in the neutron-proton final-state interaction. The new data provide a strong constraint on theoretical models