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Future Cold BPMs at DESY. D. Nölle, MDI 1.12.06. One injector initially installed. Connection to 2 nd stage upgrade included in beam distribution layout. Motivation: X-FEL. Superconducting 20 GeV LINAC With 120 Cryomodules. Properties of XFEL radiation.
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Future Cold BPMs at DESY D. Nölle, MDI 1.12.06
One injector initially installed Connection to 2nd stage upgrade included in beam distribution layout Motivation: X-FEL Superconducting 20 GeV LINAC With 120 Cryomodules
Properties of XFEL radiation • X-ray FEL radiation (0.2 - 14.4 keV) • ultrashort pulse duration <100 fs (rms) • extreme pulse intensities 1012-1014 ph • coherent radiation x109 • average brilliance x104 • Spontaneous radiation (20-100 keV) • ultrashort pulse duration <100 fs (rms) • high brilliance Goal 30.000 Pulses/s
Just for Info: Accelerator Layout Parm’s 1) The limitation to 3,000 bunches at 20 GeV beam energy is related to a maximum load of 300 kW on each of the beam dumps in the initially installed two electron beam lines.
3.4km Overall layout and site
XFEL Cryo Module • BPMs are the only monitor installed • In the 1.2 km long main LINAC • They sit every 12 m at the end of • the cavity string together with • Quadrupole • Steerer pair • HOM Absorber
HOM absorber bellows BPM quadrupole gate valve In More Detail • Cold BPM with well defined „Interface“ • Resolution < 50 µm, single Bunch (RMS) @ 0.3 – 1.2 nC, circular shaped beam • Coupling x/y < 1 % • Particle Free, at least to Class 100 • Beampipe 78 mm, stainless, copper plated • Length 170 mm • „Cavity Fanges2, fixed type on both sides • Fixed directly to the cold quad • Tolerances (Electrical to magnetical axis) • 300 µm (RMS) Transversal • 3 mrad (RMS) Roll angle
Two Candiates for the Cold BPM Pick-up Reentrant • Two Prototypes are installed in TTF, close to each other • DESY Pick up: First Tests with „Neumann Electronics“ • CEA Reentrant: • Installed, first RF Tests • Beam Test in the next Accelerator Physics Period of TTF TTF Installation
Pickup „Prototype“ • Needs more Investigation of • Button Size/Geometrie • Feedthrough Technology • Beam Tests have shown Resolution better 50 µm @ 1 nC
Q = 0.5 nC y Hor. Beam Postion x Calc. Steerer Kick First Beam Measurements: 13ACC7 with modified HERA Electronics • Prototype electronics using the Delay Line Principle • Peak Detektor sampled with an 81 MHz VME ADC with DOOCS integration • SB BPM Resolution @ 0.9 nC: 25 µm • (measured using correlation techniques)
Reentrant Cavity BPM Already presented by Claire • Collaboration with CEA Saclay • Potential of much higher resolution (< 10 µm) • Mechanics more complicated • Cleaning for particle cleanness more problematic. • Possible BPM for ILC ?
wakefield spectrum Higher Order Modes (HOM) in Accelerating Cavities • other modes: Higher Order Modes (HOM) • excited by the electron beam (unavoidable) • monopole, dipole, quadrupole etc. modes • Need to be damped • Why not use them as Cavity BPMs • All Cavities have HOM Couplers • Potential for sub µm Resolution