A Synchrotron-Light Interferometer for PEP-II
Transverse profile measurements in PEP-II, by imaging visible synchrotron emission from dipoles in the two rings, are broadened by surface errors on the primary extraction mirrors, due to the complex design to tolerate high beam currents. To improve vertical beam-size measurements, the authors recently installed a synchrotron-light interferometer, based on the concept of Mitsuhashi at KEK. In a two-slit interferometer, single-slit fringes are modulated by interference between the slits. Partial coherence decreases the modulation depth as the size of the emitting source increases, providing a sensitive measure of beam size. Because the slits pass light from two stripes along the mirror, they can select the better parts of the surface. In addition, segments of these stripes can be chosen by imaging the mirror onto the camera with a cylindrical lens, in the direction perpendicular to the fringe modulation. The interferometer is on the low-energy ring, 30 m from the BaBar detector, where the beam ellipse is tilted by 10{degree} as they compensate for rotation in BaBar's solenoid. The design rotates the interferometer to measure the beam tilt. All optics are in the PEP tunnel and allow remote adjustment of the focusing, slit width and separation.
- Research Organization:
- SLAC National Accelerator Lab., Menlo Park, CA (United States)
- Sponsoring Organization:
- USDOE Office of Energy Research (ER) (US)
- DOE Contract Number:
- AC03-76SF00515
- OSTI ID:
- 763777
- Report Number(s):
- SLAC-PUB-8456; TRN: US0004813
- Resource Relation:
- Other Information: PBD: 23 May 2000
- Country of Publication:
- United States
- Language:
- English
Similar Records
Fringe Pattern of the PEP-II Synchrotron-Light Interferometers
Turn-by-Turn Imaging of the Transverse Beam Profile in PEP-II