| Paper |
Title |
Page |
| TUPB20 |
Large Horizontal Aperture BPM and Precision Bunch Arrival Pickup
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108 |
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- K. E. Hacker, F. Löhl, H. Schlarb
DESY, Hamburg
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The large horizontal aperture chicane BPM and the precision bunch arrival monitor at FLASH will be important tools to stabilize the arrival-time of the beam at the end of the linac. The pickups for these monitors will be paired with front-ends that sample the zero-crossing of the beam transient through the use of electro-optical modulators and sub-picosecond-long laser pulses delivered by the master-laser oscillator. The design of pickups for this front-end requires the consideration of the beam transient shape as well as the amplitude. Simulations and oscilloscope traces from pickups that use or will use the EOM based phase measurement and the expected limitations and benefits of each pickup are presented. In particular, the design for a 5 um resolution BPM with a 10 cm horizontal aperture is demonstrated in terms of its capability to measure the beam energy and its sensitivity to the shape and orientation of the beam.
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| WEPB15 |
A Sub-50 Femtosecond bunch arrival time monitor system for FLASH
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262 |
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- F. Löhl, K. E. Hacker, H. Schlarb
DESY, Hamburg
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A bunch arrival time monitor system using the future laser based synchronization system at FLASH has been developed. The signal of a beam pick-up with several GHz bandwidth is sampled by a sub-ps laser pulse using a broadband electro-optical modulator. Bunch arrival time deviations are converted into amplitude modulations of the sampling laser pulses which are then detected by a photo-detector. A resolution of 30 fs could be reached, with the capability towards sub-10 fs level. In this paper we describe the design of the optical system and we present recent results.
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| WEPC02 |
Developments at Elettra of the Electronics for the Bunch-Arrival Monitor
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310 |
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- L. Pavlovič, T. Korošec, M. Vidmar
Uni LJ, Ljubljana
- M. Ferianis, F. Rossi
ELETTRA, Basovizza, Trieste
- K. E. Hacker, F. Löhl, H. Schlarb
DESY, Hamburg
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Within the framework of the EUROFEL project, a task has been started in 2006 for a joint development of a Bunch Arrival Monitor (BAM), based on the original idea from DESY. ELETTRA is responsible for the development of the VME-controlled clock-delay board of the BAM system. A variable clock-delay circuit (a phase shifter) is required to adjust the acquisition sampling point of the pick-up-modulated optical pulses of the master-laser oscillator. Since the optical pulses have a repetition rate of 40.625MHz (54MHz in the future) and the acquisition sampling frequency is double of this value, the clock-delay module operates in the 80-120MHz frequency range. The clock timing jitter of the acquisition system greatly affects the measurements of the system: the output timing jitter from the clock-delay board should be less than 0.5ps-rms. Therefore, due to the very strict additive timing-jitter requirements, three phase shifter versions were designed, built and phase-noise evaluated. Low-pass-filter implementation achieved 563fs (at 283fs source jitter) of total-system timing jitter, integrated IQ multiplier 365fs (at 188fs of source) and passive IQ modulator 265fs (at 208fs of source).
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