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Connolly, R.

Paper Title Page
TUPSM010 Residual-Gas-Ionization Beam Profile Monitors in RHIC 116
 
  • R. Connolly, J.M. Fite, S. Jao, S. Tepikian, C. Trabocchi
    BNL, Upton, Long Island, New York
  
 

Four ionization profile monitors (IPMs) in RHIC measure vertical and horizontal beam profiles in the two rings. These work by measuring the distribution of electrons produced by beam ionization of residual gas. In 2007 a prototype of a new design was installed in the yellow ring. During the 2007-2008 run it proved to be almost completely free from backgrounds from rf coupling, electron clouds and x-rays from upstream beam loss. In 2009 two more IPMs of this new design were installed and in the 2010 shutdown we will complete installation of four identical IPMs. This paper describes the new IPMs and shows data from the 2010 beam run. The new IPMs have been extremely important in the commissioning of the RHIC stochastic cooling system.

  
TUPSM011 Beam-Energy and Laser Beam-Profile Monitor at the BNL Linac 119
 
  • 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.