BNL, Upton, Long Island, New York, USA
The Relativistic Heavy Ions Collider (RHIC) would benefit from improved beam position measurements near the interaction points that see both beams, especially as the tolerances become tighter when reducing the beam sizes to obtain increased luminosity. Two limitations of the present beam position monitors (BPMs) would be mitigated if the proposed approach is successful. The small but unavoidable cross-talk between signals from bunches traveling in opposite directions when using conventional BPMs will be reduced by adopting directional BPMs. Further improvements will be achieved by cancelling residual cross-talk using pairs of such BPMs. Appropriately delayed addition and integration of the signals will also provide pulses with relatively flat maxima that will be easier to digitize by relaxing the presently very stringent timing requirements.
BNL, Upton, Long Island, New York, USA
The optimal performance of the two electron lenses that are being implemented for high intensity polarized proton operation of RHIC requires excellent collinearity of the ~0.3 mm RMS wide electron beams with the proton bunch trajectories over the ~2m interaction lengths. The main beam overlap diagnostic tool will make use of electrons backscattered in close encounters with the relativistic protons. These electrons will spiral along the electron guiding magnetic field and will be detected in a plastic scintillator located close to the electron gun. A fraction of these electrons will have energies high enough to emerge from the vacuum chamber through a thin window thus simplifying the design and operation of the detector. The intensity of the detected electrons provides a measure of the overlap between the e- and the opposing proton beams. Joint electron arrival time and energy discrimination may be used additionally to gain some longitudinal position information with a single detector per lens.
BNL, Upton, Long Island, New York, USA
The goal of the Coherent Electron Cooling Proof-of-Principle experiment being designed at RHIC is to demonstrate longitudinal (energy spread) cooling before the expected CD-2 for eRHIC. The scope of the experiment is to cool longitudinally a single bunch of 40GeV/u Au ions in RHIC. This paper will describe the instrumentation systems proposed to meet the diagnostics challenges. These include measurements of beam intensity, emittance, energy spread, bunch length, position, orbit stability, and transverse and temporal alignment of electron and ion beams.