Abstract
Nuclear physics experiments at Thomas Jefferson National Accelerator Facility's CEBAF rely on high polarization electron beams. We describe a recently commissioned system for prequalifying and studying photocathodes for CEBAF with a load-locked, low-voltage polarized electron source coupled to a compact retarding-field Mott polarimeter. The polarimeter uses simplified electrode structures and operates from 5 to 30kV. The effective Sherman function for this device has been calibrated by comparison with the CEBAF 5 MeV Mott polarimeter. For elastic scattering from a thick gold target at 20keV, the effective Sherman function is 0.201(5). Its maximum efficiency at 20keV, defined as the detected count rate divided by the incident particle current, is 5.4(2) × 10-4, yielding a figure-of-merit, or analyzing power squared times efficiency, of 1.0(1) × 10-5. The operating parameters of this new polarimeter design are compared to previously published data for other compact Mott polarimeters of the retarding-field type.
Original language | English (US) |
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Pages (from-to) | 30-36 |
Number of pages | 7 |
Journal | Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment |
Volume | 618 |
Issue number | 1-3 |
DOIs | |
State | Published - Jun 1 2010 |
Externally published | Yes |
Keywords
- Mott
- Polarimeter
- Polarization
- Source
ASJC Scopus subject areas
- Nuclear and High Energy Physics
- Instrumentation