BNL, Upton, Long Island, New York, USA
The operating parameters for Brookhaven National Laboratory's Low Energy RHIC Electron Cooling (LEReC) project create a unique challenge. To ensure proper beam trajectories for cooling, the relative position between the electron and the ion beam needs to be known to within 50μm. In addition, time of flight needs to be provided for electron beam energy measurement. Various issues have become apparent as testing has progressed, such as mismatches in cable impedance and drifts due to temperature sensitivity. This paper will explore the difficulties related to achieving the level of accuracy required for this system, as well as the potential solutions for these problems.
BNL, Upton, Long Island, New York, USA
RHIC will be run at low ion beam center-of-mass energies of 7.7 - 20 GeV/nucleon, much lower than the typical operations at 100 GeV/nucleon. The primary motivation is to explore the existence and location of the critical point on the QCD phase diagram. An electron accelerator is being constructed to provide Low Energy RHIC electron Cooling (LEReC) to cool both the blue & yellow RHIC ion beams by co-propagating a 10 - 50 mA electron beam of 1.6 - 2.6 MeV. This cooling facility will include a 400 keV DC gun, SRF booster cavity and a beam transport with multiple phase adjusting RF cavities to bring the beam to one ring to allow electron-ion co-propagation for ~21 m, then through a 180° U-turn electron transport so that the same electron beam can similarly cool the other counter-rotating ion beam, and finally to a beam dump. The injector commissioning is planned to start in early 2017 and full LEReC commissioning planned to start in early 2018. The instrumentation systems that will be described include current transformers, BPMs, profile monitors, multi-slit and single slit scanning emittance stations, time-of-flight and magnetic energy measurements, and beam halo & loss monitors.
BNL, Upton, Long Island, New York, USA
A new BPM electronics module (V301) has been developed at BNL that uses the latest System on a Chip (SoC) technologies to provide a system with better performance and lower cost per module than before. The future of RHIC ion runs will include new RF conditions as well as a wider dynamic range in intensity. Plans for the use of electron beams, both in ion cooling applications and a future electron-ion collider, have also driven this architecture toward a highly configurable approach. The RF input section has been designed such that jumpers can be changed to allow a single board to provide ion or electron optimized analog filtering. These channels are sampled with four 14-bit 400MSPS A/D converters. The SoC's ARM processor allows a Linux OS to run directly on the module along with a controls system software interface. The FPGA is used to process samples from the ADCs and perform position calculations. A suite of peripherals including dual Ethernet ports, uSD storage, and an interface to the RHIC timing system are also included. A second revision board which includes ultra-low jitter ADC clock synthesis and distribution and improved power supplies is currently being commissioned.