Parity Quality Beam

A significant portion of the experiments performed at Jefferson Lab require a polarized electron beam. A subset of these are parity violation experiments which have exceptionally stringent requirements on the quality of the electron beam. As the sign of the electron beam helicity reverses at the target of the experiment no other measurable quantity of the electron beam may change. This includes the beam intensity, polarization, position, angle, energy or spot size.

To ensure this beam quality, a significant effort occurs at the polarized electron source, where the laser beam and electron photogun combine to produce the intended electron beam. Also significant is the ability to accelerate the beam to high energy while transporting it to the experimental target, all while maintaining a parity quality electron beam.

Parity Violation

Discussion of parity violation can be found at NIST: The Fall of Parity: [1]

Parity Violation Experiments

1. JLab Hall A Parity Experiments (HAPPEX, PREX, C-REX, PVDIS): [2]
2. JLab Hall C G0 Experiment: [3]
3. JLab Hall C QWeak Experiment: [4]
4. JLab Hall A Moller Experiment: [5]
5. Mainz A4 Experiment: [6]

References

1. el’dovich Ya. B.,Sov. Phys. JETP,94 (1959) 262

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1. G0 Backward Angle Run
2. JLab Gun Group G0 experiment homepage
3. LESSONS LEARNED for parity violation experiments at Jefferson Laboratory is an on-going series of meetings between scientists and students from the accelerator and physics division to learn from past experiences and meet new challenges in the field of parity violation experiments.
4. Quick links to useful slides and talks:
   1. Parity Violation Experiments at CEBAF Beam Specifications (PPT), Matt Poelker, March 4, 2004