We are designing two electron lenses that will be installed at RHIC IR10 to compensate for the head-on beam-beam effect. To clear accumulated scattered electrons from 100 GeV proton-electron head-on collisions in the e-lens, a clearing split electrode may be constructed. The feasibility of this proposed electrode was demonstrated via the CST Particle Studio and Opera program simulations. By splitting one of the drift tubes in the e-lens and applying {approx} 380 V across the two parts, the scattered electrons can be cleared out within several hundred micro-seconds. At the same time we can restrict the unwanted shift of the primary electron-beam that already passed the 2-m interaction region in e-lens, to less than 15um.

43 PARTICLE ACCELERATORS↗

DOE OSTI2012

A wire scanner system for characterizing the BNL energy recovery LINAC beam position monitor system

A stepper motor controlled wire scanner system has recently been modified to support testing of the Brookhaven National Laboratory (BNL) Collider-Accelerator department's Energy Recovery Linac (ERL) beam position monitor (BPM) system. The ERL BPM consists of four 9.33 mm diameter buttons mounted at 90 degree spacing in a cube with 1.875 inch inside diameter. The buttons were designed by BNL and fabricated by Times Microwave Systems. Libera brilliance single pass BPM electronic modules with 700 MHz bandpass filter, manufactured by Instrumentation Technologies, will be used to measure the transverse beam positions at 14 locations around the ERL. The wire scanner assembly provides the ability to measure the BPM button response to a pulsed wire, and evaluate and calibrate the Libera position measurement electronics. A description of the wire scanner system and test result data will be presented.

43 PARTICLE ACCELERATORS↗

DOE OSTI2012

Design of a proton-electron beam overlap monitor for the new RHIC electron lens, based on detecting energetic backscattered electrons

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 {approx}0.3 mm RMS wide electron beams with the proton bunch trajectories over the {approx}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.

43 PARTICLE ACCELERATORS↗

DOE OSTI2012

Conceptual design of a high precision dual directional beam position monitoring system for beam crosstalk cancellation and improved output pulse shapes

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.

43 PARTICLE ACCELERATORS↗

DOE OSTI2011

Closing plenary summary of working group 4 instrumentation and controls for ERL2011

Working group 4 was charged with presentations and discussions on instrumentation and controls with regards to Energy Recovery Linacs (ERL). There were 4 sessions spanning 3.5 hours in which 7 talks were delivered, the first being an invited plenary presentation. The time allotted for each talk was limited to 20-25 minutes in order to allow 5-10 minutes for discussion. Most of the talks were held in joint session with working group 5 (Unwanted Beam Loss). This format was effective for the purpose of this workshop. A final series of discussion sessions were also held with working group 5. Summary of the working group 4 activities, presented in the closing plenary session. We had a plenary presentation on operational performance, experience, and future plans at the existing ERL injector prototype at Cornell. This included instrumentation data, controls system configurations, as well as description of future needs. This was followed by four talks from KEK and RIKEN/SPring-8 that described electron beam instrumentation already in use or under development that can be applied to ERL facilities. The final talks described the ERLs under construction at KEK and BNL. The format of having joint sessions with working group 5 was beneficial as there were a significant number of common topics and concerns with regards to the causes of beam loss, instrumentation hardware, and techniques used to measure and analyze beam loss.

43 PARTICLE ACCELERATORS↗

DOE OSTI2011

Controls system developments for the ERL facility

The BNL Energy Recovery LINAC (ERL) is a high beam current, superconducting RF electron accelerator that is being commissioned to serve as a research and development prototype for a RHIC facility upgrade for electron-ion collision (eRHIC). Key components of the machine include a laser, photocathode, and 5-cell superconducting RF cavity operating at a frequency of 703 MHz. Starting with a foundation based on existing ADO software running on Linux servers and on the VME/VxWorks platforms developed for RHIC, we are developing a controls system that incorporates a wide range of hardware I/O interfaces that are needed for machine R&D. Details of the system layout, specifications, and user interfaces are provided.

43 PARTICLE ACCELERATORS↗