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DORIS. Vacuum system Available beam scraper Beam dimensions, Target cell Machine Studies on February 7 th 2009 Further machine studies. Straight section from the arc to the IP. Main source of synchrotron radiation. Horizontal scraper. Vertical scraper. Horizontal scraper.
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DORIS • Vacuum system • Available beam scraper • Beam dimensions, Target cell • Machine Studies on February 7th 2009 • Further machine studies Olympus Meeting at DESY, F.Brinker
Straight section from the arc to the IP Main source of synchrotron radiation Horizontal scraper Vertical scraper Horizontal scraper Olympus Meeting at DESY, F.Brinker
Horizontal and vertical scraper Water cooled copper rod, 30mm diam. Olympus Meeting at DESY, F.Brinker
Acceptance and Beam sizes at 4.5 GeV ( σ~E ) The acceptance, defined by existing aperture limitations, is a bit larger than the space needed for the injection Olympus Meeting at DESY, F.Brinker
Vacuum system Adapter chambers new position new position valves to be removed current position current position Olympus Meeting at DESY, F.Brinker
Geometry of new IP region may be a bit more Olympus Meeting at DESY, F.Brinker
Machine studies on February 7th • Injection into 10 bunches • Final current 170 mA after 6 minutes • Varying efficiency – probably due to effects at DESY: • DESY operated at normal maximum energy of 4.5 GeV • At 2.3 GeV the beam is not fully damped to its equilibrium emittance • Possibly beam blow up due to resonances • Room for improvements: • New power supplies with higher stability • Extraction when beam is decelerated • Optimization of top energy Olympus Meeting at DESY, F.Brinker
Machine studies on February 7th Stored beam with good conditions: • I = 150 mA • Lifetime = 8.5 hours Not so nice: Longitudinal beam excitation (oscillation with ~1cm Amplitude) Limits lifetime at higher currents maybe increased particle background Olympus Meeting at DESY, F.Brinker
Vacuum pressure in cavities 3.1/3.2 Observation: Pressure increase at cavities 3.1/3.2 Probable explanation: The high bunch currents excite a higher order mode in these cavities – leading both to an pressure increase and a longitudinal beam excitation Olympus Meeting at DESY, F.Brinker
Longitudinal oscillations at 4.5 GeV Increased cavity temperature Test: reduced temperature of Cav. 3.2 Olympus Meeting at DESY, F.Brinker
Further machine studies in 2009/10: • Injection at 2.3 / 2.0 GeV • Maximize transport line transmission • Optimize DESY parameter • Try to eject during deceleration • Longitudinal Oscillations • Effect of cav. temperatures at 4.5 GeV • Installation of second RF-amplifier for long. FB ( July 2009 ) • Repeat measurements at 2.3 / 2.0 GeV • Scraper studies ( with background counters ? ) • Simulate dimensions of target cell • Verify beam sizes/ acceptance with scrapers at low energies • Injection tests with closed scrapers ( background spikes? ) Olympus Meeting at DESY, F.Brinker