PAC2013 - List of Authors (Pai, C.)

Paper	Title	Page
WEPBA05	Combining Multiple BPM Measurements for Precession AC Dipole Bump Closure	892
	P. Oddo, M. Bai, W.C. Dawson, J. Kewisch, Y. Makdisi, C. Pai, P.H. Pile, T. Roser BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy Energy and RIKEN, Japan. For the RHIC spin flipper to achieve a rotating field, it requires operating five AC dipoles as a pair of closed orbit bumps. One key requirement is to minimize the remnant AC dipole driven betatron oscillation outside of the spin flipper by 50dB. In the past, due to its inherent sensitivity, a single pickup with a direct-diode detector (3D) and dynamic signal analyzer (DSA) were used to measure bump closure by measuring the remnant oscillations. This however proved to be inadequate, as the betatron phase advance between the AC dipoles is non-zero. A method of combining multiple BPMs into a sensitive measure of bump closure has been developed and will be tested during RHIC polarized proton operation in 2013. This technique as well as the experimental results will be presented.

THPHO09	High Intensity RHIC Limitations Due to Signal Heating of the Cryogenic BPM Cables	1319
	P. Thieberger, J.A. D'Ambra, A.K. Ghosh, K. Hamdi, K. Mernick, T.A. Miller, M.G. Minty, C. Pai BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The signal cables from the beam position monitors (BPMs) in the cryogenic sections of RHIC need to satisfy somewhat conflicting requirements. On the one hand, the cryogenic load due to heat conduction along the cable needs to be small, which led to the use of stainless steel jacketed cables with Tefzel insulation. On the other hand, radio frequency losses need to be reasonably small to reduce heating due to dissipated signal power. As the beam intensity in RHIC increased over the years, and the bunches become shorter, a point is being rapidly approached where these cables will soon become a performance limiting factor. Here we describe an extensive study of this problem including cable loss measurements as a function of temperature and frequency, characterization of the copper center conductor, and Particle Studio and ANSYS simulations.

Paper

Title

Page

Combining Multiple BPM Measurements for Precession AC Dipole Bump Closure

892

P. Oddo, M. Bai, W.C. Dawson, J. Kewisch, Y. Makdisi, C. Pai, P.H. Pile, T. Roser
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy Energy and RIKEN, Japan.
For the RHIC spin flipper to achieve a rotating field, it requires operating five AC dipoles as a pair of closed orbit bumps. One key requirement is to minimize the remnant AC dipole driven betatron oscillation outside of the spin flipper by 50dB. In the past, due to its inherent sensitivity, a single pickup with a direct-diode detector (3D) and dynamic signal analyzer (DSA) were used to measure bump closure by measuring the remnant oscillations. This however proved to be inadequate, as the betatron phase advance between the AC dipoles is non-zero. A method of combining multiple BPMs into a sensitive measure of bump closure has been developed and will be tested during RHIC polarized proton operation in 2013. This technique as well as the experimental results will be presented.

THPHO09

High Intensity RHIC Limitations Due to Signal Heating of the Cryogenic BPM Cables

1319

P. Thieberger, J.A. D'Ambra, A.K. Ghosh, K. Hamdi, K. Mernick, T.A. Miller, M.G. Minty, C. Pai
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The signal cables from the beam position monitors (BPMs) in the cryogenic sections of RHIC need to satisfy somewhat conflicting requirements. On the one hand, the cryogenic load due to heat conduction along the cable needs to be small, which led to the use of stainless steel jacketed cables with Tefzel insulation. On the other hand, radio frequency losses need to be reasonably small to reduce heating due to dissipated signal power. As the beam intensity in RHIC increased over the years, and the bunches become shorter, a point is being rapidly approached where these cables will soon become a performance limiting factor. Here we describe an extensive study of this problem including cable loss measurements as a function of temperature and frequency, characterization of the copper center conductor, and Particle Studio and ANSYS simulations.