Inclusive scattering of polarized electrons from polarized protons in the Delta-excitation region with BLAST.

摘要

Inclusive scattering of polarized electrons from polarized protons has been studied using the BLAST detector at MIT-Bates Linear Accelerator Center. The Bates Large Acceptance Spectrometer Toroid (BLAST) is a detector designed to study in a comprehensive and precise way the spin-dependent electromagnetic response in one and few-body systems over a large kinematic range. It has been used to measure spin-dependent scattering from the elastic to the nucleon resonance region for hydrogen and deuterium using a longitudinally polarized electron beam at a beam energy of 850 MeV stored in the MIT-Bates South Hall Ring, and polarized internal gas targets of hydrogen and deuterium. There are several reasons for studying the inclusive p&ar;&parl0;e&ar; , e') reaction: first, since all pion production models predict its observables, this is a stringent test for these models; second, due to detector acceptance confinements, inclusive scattering provides a higher statistical accuracy than exclusive scattering, where a hadron is measured in coincidence with the scattered electron, and additional systematic uncertainties from the exclusive reaction, due to the energy and angular resolution of the hadron detector, are avoided as well; third, the double-polarized scattering with BLAST over a range of momentum transfer Q2 = [0.08, 0.38] GeV2 provides unique, accurate data to check these models.