1. A U.S. Department of Energy Office of Science Laboratory Operated by The University of Chicago Argonne National Laboratory Office of Science U.S. Department of Energy Project 520: Bunch Cleaning System 1. Progress report on Par bunch cleaning (P312 FY05) 2. Storage ring bunch cleaning system (P520 FY05)

2. 1 Pioneering Science and Technology Office of Science U.S. Department of Energy Progress Report: PAR Bunch Cleaning System Project No: 312 Coordinator: CY Yao Activities: The objective of the Par Bunch Cleaning project is to design and develop a bunch cleaning system that reduces the satellite bunches in the PAR to 1.0×10 -8 level. This is a multi-year project. Main goal of bunch cleaning in the PAR has been achieved. We now can consistently maintain SR bunch purity of 2.0×10 -7 during a long top-up operation period. Based on this result the PAR bunch purity is estimated to be better than 4.0×10 -8. This basically has satisfied user’s need. Current status: The par bunch cleaning system is basically completed and has been tested during user operation for two runs and produced satisfactory results. Budget Allocated $111.4K FY05 expenditure $70.2K Plan and schedule: Complete all the system hardware/software to meet the requirement for normal operation and hand over the system to MCR group at the beginning of FY06. Complete upgrading of SR bunch purity measurement system in FY06.

3. 1 Pioneering Science and Technology Office of Science U.S. Department of Energy +1 -2-3 Recent data from 24 singlet user run. Bunch purity for bucket number +2 or higher was not observed due to the 5 min. accumulation time specified for this data set.

4. 1 Pioneering Science and Technology Office of Science U.S. Department of Energy Project: (AOD 520): Completion of Project 312 PAR Bunch Cleaning Systems Objective: Complete commissioning of the operational PAR bunch cleaning system deployed in FY05. Complete upgrade to bunch purity measurement system in the storage ring to allow detection of 5e-9 impurity in a reasonable time period. Develop and install bunch cleaning system for the storage ring. Background Information: Ongoing Initiative Multi Year Funding High priority Justification: Assure good bunch purity in the storage ring to support experiments that are sensitive to it, as is done at both ESRF and SPring-8. Eliminate the necessity of dumping stored beam in the event of PAR system malfunctions that can result in corrupting the storage ring fill pattern. Consequence: Consistent bunch purity in the storage ring cannot be guaranteed without implementation of the PAR system. The ability to perform bunch cleaning in the storage ring will provide a backup capability, which may be necessary to assure bunch purity at the 1e-8 level or better. This is especially important considering the very low fault rate in the storage ring resulting in mean time between failures exceeding three days.

5. 1 Pioneering Science and Technology Office of Science U.S. Department of Energy FY06 cost: $178.22 K FY200620072008Total Non-effort$178.22 K Effort$121.19 K New Effort Total$299.41 K

6. 1 Pioneering Science and Technology Office of Science U.S. Department of Energy 0º0º180º main bucket satellite buckets 180º0º0º Bunch cleaning using phase modulation drive Phase modulated drive signal Vertical tune signal

7. 1 Pioneering Science and Technology Office of Science U.S. Department of Energy Advantages Main buckets are not effected by the RF drive. All satellites buckets are driven by full amplitude of RF drive. Compatible with top-up operation. Bandwidth of the amplifiers and other RF circuits is reduced to half compared with AM modulation method. Total cost is reduced. The system can also be used to “repair” stored beam if the bunch purity is corrupted. The method has been employed in other laboratory such as ESRF and Spring-8.

8. 1 Pioneering Science and Technology Office of Science U.S. Department of Energy Challenges Power requirement is substantially higher than that required by PAR bunch cleaning: -Beam energy is 20 times higher. -Scrapers can not be used due to top-up operation. Strong dependency of SR tune on betatron oscillation amplitude due to higher chromaticity makes tracking of the resonance tune harder. Make the system as transparent as possible to the users.

9. 1 Pioneering Science and Technology Office of Science U.S. Department of Energy References 1. Glenn Decker, “Recommendation of the ad-hoc working group investigation options for achieving bunch purity in the APS storage ring,” http://www.aps4.anl.gov/diagnostics/bunchCleaning041122.pdf 2. “Bunch cleaning in the ESRF booster,” Proceedings of EPAC04, Lucerne, Switzerland. http://accelconf.web.cern.ch/accelconf/e04/PAPERS/THPKF032.PDF