PhD Thesis of Christoph Steier

I finished my PhD thesis on acceleration of polarized electrons in ELSA in March 1999.

Title:
Polarisierte Elektronen in der Elektronen-Stretcher-Anlage ELSA

Abstract:

For measurements of the spin structure of the nucleon a polarized electron beam is needed up to the maximum beam energy of the Electron Stretcher Accelerator ELSA. The polarized electrons are produced in a dedicated source using the photo effect with circularly polarized laser light on a GaAs superlattice crystal. To conserve the polarization level throughout the energy ramp it is necessary to cross and correct for several depolarizing resonances. The differences in the resonance crossing process compared to previous experiments at proton accelerators were studied in detailed simulations. For this purpose a spin tracking code (SPTRACK) was implemented that includes the effects of synchrotron oscillations and synchrotron radiation on the resonance crossing. Based on the results of these calculations a harmonic correction scheme was adopted for imperfection resonances. A system of pulsed quadrupole magnets to prevent depolarization due to intrinsic resonances was designed, constructed and installed at the accelerator. Several measurements performed with polarized beam in ELSA showed good agreement with all predictions of the simulations. All correction methods worked as expected. Recently polarized electrons have been accelerated up to 2.1 GeV with only small depolarization.

Proceedings of the 18th Particle Accelerator Conference, New York 1999,
C. Steier et al.

Crossing Intrinsic Depolarizing Resonances in ELSA with Pulsed Betatron Tune Jump Quadrupoles

Nucl. Instr. and Meth. A 424 (1999) 277-295,
M. Gentner et al.

On the possibilities of electron cooling for HERA

Nucl. Instr. and Meth. A 411 (1998) 93-106,
S. Nakamura et al.

Polarized Electrons in ELSA

Proceedings of the 6th European Particle Accelerator Conference, Stockholm 1998,
M. Gentner et al.

Electron Cooling Possibilities for HERA

Proceedings of the 6th European Particle Accelerator Conference, Stockholm 1998,
C. Steier et al.

Acceleration of Polarized Electrons in ELSA

Proceedings of the 1st Asian Particle Accelerator Conference, KEK Tsukuba 1998,
S. Nakamura et al.

Polarized Electrons at 3.5 GeV ELSA (Bonn)

AIP Conference Proceedings 421, 7th workshop on polarized targets and beams, Urbana (1997) 497
S. Nakamura et al.

Polarized Electrons in ELSA (preliminary results)

Proceedings of the 17th Particle Accelerator Conference, Vancouver 1997,
C. Steier, D. Husmann

Correction of Depolarizing Resonances in ELSA

CSteier@lbl.gov