Luminosity-driven channeling extraction has been observed for the first time in a 900 GeV study at the Fermilab Tevatron. This experiment, Fermilab E853, demonstrated that useful TeV level beams can be extracted from a superconducting accelerator during high luminosity collider operations without unduly affecting the background at the collider detectors. Multi-turn extraction was found to increase significantly the efficiency of the process. The beam extraction efficiency was about 25%. Studies of time dependent effects found that the turn-to-turn structure was governed mainly by accelerator beam dynamics. An investigation of a pre-scatterer using the accelerator flying wire system showed that a fiber could produce a significant extracted flux, consistent with expectations. Based on these results, it is feasible to construct a parasitic 5-10 MHz proton beam from the Tevatron collider.Comment: 55 page

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Spin precession of channeled particles in bent crystals has been observed for the first time. Polarized I"*" were channeled using bent Si crystals. These crystals provided an effective magnetic field of 45 T which resulted in a measured spin precession of 60° ±17°. This agrees with the prediction of 62° ± 2° using the world average of Z"*" magnetic moment measurements. This new technique gives a I"*" magnetic moment of (2.40 ± 0.46 ± 0.40)/X7v, where the quoted uncertainties are statistical and systematic, respectively. We see no evidence of depolarization in the channeling process. PACS numbers: 13.40.Fn, 14.20.Jn, 61.80.MkChanneling of high-energy particles in bent crystals has been observed in the momentum range [1-5] of 1.7-800 GeV/c. This technique has already found applications [3][4][5] in the deflection of high-energy beams. Another possibly important application of channeling is the precession of the spin of a polarized particle. This may allow the measurement of magnetic moments in distances of only a few cm. The lifetimes [6] of baryons containing charm quarks are so short that they travel only a few centimeters even at the highest available accelerator energies. Because of these short lifetimes, classical spin precession techniques using conventional magnets would produce negligibly small spin precession angles.It was pointed out by Baryshevskii [7] and Pondrom [8] that the magnetic moments of particles should precess if they were channeled in a bent crystal. The detailed precession theory has been developed by Lyuboshits [9] and Kim [10]. In a curved crystal the electrostatic field of the atomic planes deflecting the particle transforms into a magnetic field in the particle's rest frame. Thus the spin precession angle ^ is [9]

Collimation of proton and antiproton beams in the Tevatron collider is required to protect CDF and D0 detectors and minimize their background rates, to keep irradiation of superconducting magnets under control, to maintain long-term operational reliability, and to reduce the impact of beam-induced radiation on the environment. In this article we briefly describe the design, practical implementation and performance of the collider collimation system, methods to control transverse and longitudinal beam halo and two novel collimation techniques tested in the Tevatron.

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