Bent crystal channeling has been observed with protons and fully stripped gold ions in the Relativistic Heavy Ion Collider (RHIC). Prior to 2003, a bent crystal was installed in one ring of RHIC as the first stage of a two stage collimation system. The observed channeling efficiency was approximately 25%, less than half of original predictions. We show that this is due to a difference between the model and real Twiss parameters at the crystal location and our improved understanding of the beam halo. Collimation using the crystal was unsuccessful and raised background at the STAR detector by as much as a factor of 2 because of the low channeling efficiency. We give a report of our channeling studies in RHIC and describe our experience using the bent crystal as a collimator. The results are discussed and compared to simulations and theoretical predictions.

We report optical double-resonance spectroscopy to locate and study the 7D 3/2 and 7D 5/2 levels of a sample of 210 Fr atoms confined and cooled in a magneto-optical trap. The upper state of the 7 P 3/2 trapping transition serves as the resonant intermediate level to reach the 7D states. The energy difference to the ground state is measured for the accessible levels. We measure the hyperfine splittings: ⌬(7D 3/2 ,Fϭ15/2↔13/2)ϭ167 Ϯ4 MHz, ⌬(7D 5/2 ,Fϭ17/2↔15/2)ϭϪ117.5Ϯ2.5 MHz, and ⌬(7D 5/2 ,Fϭ15/2↔13/2)ϭϪ121Ϯ4 MHz. Extrapolating the energies of the inaccessible hyperfine levels from the hyperfine constants and assuming B(7D 3/2 )ϭ0, the center-of-gravity energy difference to the ground state is E(7D 3/2 )ϭ24 244.831 Ϯ0.003 cm Ϫ1 and E(7D 5/2 )ϭ24 333.298Ϯ0.003 cm Ϫ1 .

An experimental program to demonstrate a novel phase space manipulation in which the horizontal and longitudinal emittances of a particle beam are exchanged has been completed at the Fermilab A0 Photoinjector. A new beamline, consisting of a T M110 deflecting mode cavity flanked by two horizontally dispersive doglegs has been installed. We report on the first direct observation of transverse and longitudinal emittance exchange: {ε nx , ε n y , ε n z }={2.9 ± 0.1, 2.4 ± 0.1, 13.1 ± 1.3}⇒{11.3 ± 1.1, 2.9 ± 0.5, 3.1 ± 0.3} mm-mrad.

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