DORIS Vacuum system Available beam scraper Beam dimensions

DORIS • Vacuum system • Available beam scraper • Beam dimensions, Target cell • Machine Studies on February 7 th 2009 • Further machine studies April 6 th 2009 Olympus Meeting at DESY, F. Brinker 1

Straight section from the arc to the IP Vertical scraper April 6 th 2009 Horizontal scraper Main source of synchrotron radiation Olympus Meeting at DESY, F. Brinker Horizontal scraper 2

Horizontal and vertical scraper Water cooled copper rod, 30 mm diam. April 6 th 2009 Olympus Meeting at DESY, F. Brinker 3

Acceptance and Beam sizes at 4. 5 Ge. V ( σ~E ) The acceptance, defined by existing aperture limitations, is a bit larger than the space needed for the injection April 6 th 2009 Olympus Meeting at DESY, F. Brinker 4

Vacuum system Adapter chambers new position to be removed April 6 th 2009 new position valves current position Olympus Meeting at DESY, F. Brinker current position 5

Geometry of new IP region may be a bit more April 6 th 2009 Olympus Meeting at DESY, F. Brinker 6

Machine studies on February 7 th • Injection into 10 bunches • Final current 170 m. A after 6 minutes • Varying efficiency – probably due to effects at DESY: • DESY operated at normal maximum energy of 4. 5 Ge. V • At 2. 3 Ge. V 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 April 6 th 2009 Olympus Meeting at DESY, F. Brinker 7

Machine studies on February 7 th Stored beam with good conditions: • I = 150 m. A • Lifetime = 8. 5 hours Not so nice: Longitudinal beam excitation (oscillation with ~1 cm Amplitude) Limits lifetime at higher currents maybe increased particle background April 6 th 2009 Olympus Meeting at DESY, F. Brinker 8

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 April 6 th 2009 Olympus Meeting at DESY, F. Brinker 9

Longitudinal oscillations at 4. 5 Ge. V Increased cavity temperature April 6 th 2009 Test: reduced temperature of Cav. 3. 2 Olympus Meeting at DESY, F. Brinker 10

Further machine studies in 2009/10: • Injection at 2. 3 / 2. 0 Ge. V – Maximize transport line transmission – Optimize DESY parameter – Try to eject during deceleration • Longitudinal Oscillations – Effect of cav. temperatures at 4. 5 Ge. V – Installation of second RF-amplifier for long. FB ( July 2009 ) – Repeat measurements at 2. 3 / 2. 0 Ge. V • 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? ) April 6 th 2009 Olympus Meeting at DESY, F. Brinker 11