The OOPS program at Bates

Tancredi Botto
for the OOPS collaboration

MIT-Bates Linear Accelerator Centre, MIT

We report on recent high-precision, exclusive measurements of $\gamma^{*}\mbox{N} \rightarrow \Delta$ and of virtual Compton scattering from the proton. These studies are part of the unique program pursued by the OOPS collaboration at the MIT/Bates laboratory. For the first time this year we could make use of high-duty factor, high-energy electron beams and of the complete out-of-plane spectrometer system. Data was collected in the H $(e,e^\prime p)\gamma$, H $(e,e^\prime p)\pi^0$ and H $(e,e^\prime \pi^+)n$ channels.

In this talk particular emphasis will be given to the studies of the $N\rightarrow \Delta$ transition. Due to the flexibility of the OOPS system, we measured over a vast angular region across the resonance. In this way one can selectively investigate the role of the competing background (i.e. Born) and resonance terms. We will show and discuss preliminary results on isolated response functions and compare them to theoretical calculations from which a value for the quadrupole amplitudes can be extracted.

$^1$ Contact address:
Massachusetts Institute of Technology
MIT/Bates Linear Accelerator Center
Manning Rd
Middleton, MA 01949
USA