• R. Connolly, B. Briscoe, C. Degen, W. Meng, R.J. Michnoff, M.G. Minty, S. Nayak, D. Raparia, T. Russo
  BNL, Upton, Long Island, New York

A beam profile and energy monitor for H^- beams which measures electrons stripped from the beam by a laser has been installed in the high energy beam transport (HEBT) line at the Brookhaven National Lab linac. Our 100mJ/pulse, Q-switched laser neutralizes 70% of the beam during its 10ns pulse. Also electrons are stripped by the residual gas at a rate of ~1.5 x 10^-8/cm at 1 x 10-7torr. Beam electrons have the same velocity as the beam and so have an energy of 1/1836 of the beam protons. There is a chamber in which the laser light passes through the ion beam followed by a dipole magnet which deflects the electrons by 90° through a biased retarding grid (V<125kV) into a Faraday cup detector. To measure beam profiles, a narrow laser beam is stepped across the ion beam removing electrons from the portion of the H^- beam intercepted by the laser. To measure the energy spectrum of the electrons, we use either the gas-stripped or laser-stripped signal. The total current is measured as the voltage on the grid is raised in small steps. We deduce the energy spread of the H^- beam by deconvolving the electron spectrum into components from beam energy and from space-charge fields.

• M. Wilinski, W.C. Dawson, C. Degen, A. Marusic, K. Mernick, M.G. Minty, T. Russo
  BNL, Upton, Long Island, New York

Throughout RHIC Run-9 (polarized protons) and Run-10 (gold), numerous modifications to the Baseband Tune (BBQ) system were made. Hardware and software improvements resulted in improved resolution and control, allowing the system to overcome challenges from competing 60 Hz mains harmonics, other spectral content, and other beam issues. Test points from the Analog Front End (AFE) were added and connected to diagnostics that allow us to view signals, such as frequency spectra on a Sr785 dynamic signal analyzer, in real time. Also, additional data can now be logged using a National Instruments DAQ. Development time using tune feedback to obtain full-energy beams at RHIC has been significantly reduced from many ramps over a few weeks, to just a few ramps over several hours. For many years BBQ was an expert-only system, but the many improvements allowed BBQ to finally be handed over to the Operations Staff for routine control.

• P. Oddo, M. Bai, W.C. Dawson, W. Meng, K. Mernick, C. Pai, T. Roser, T. Russo
  BNL, Upton, Long Island, New York

AC-dipole magnets are typically implemented as a parallel LC resonant circuit. To maximize efficiency, it’s beneficial to operate at a high Q. This, however, limits the magnet to a narrow frequency range. Current designs therefore deliberately spoil the Q to provide a wider bandwidth at the cost of efficiency. Dynamically tuning the resonant circuit tries to maintain a high efficiency while providing a wide frequency range. The results of ongoing efforts at BNL to implement dynamically tuned high-Q AC dipoles will be presented.