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HXRSS Design Status. P. Emma et al Feb. 25, 2011. Figure 1 of the paper…. “…introduces no path delay of x-rays”. Taper works better. 1- m m rms e - pulse length (3 fs). Taper last 10 undulators for 100-GW power level. HRXSS Physics Requirements Document:
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HXRSS Design Status P. Emma et al Feb. 25, 2011
Figure 1 of the paper… “…introduces no path delay of x-rays” Taper works better 1-mm rms e- pulse length (3 fs) Taper last 10 undulators for 100-GW power level
HRXSS Physics Requirements Document: Electron & FEL parameters (e.g., 20 pC) Chicane parameters Magnet requirements Crystal with position/angle controls Vacuum chamber requirements Bragg diagnostic requirements All tolerances
New HXR Self-Seeding Chicane for the LCLS Undulator (~U12) 3.4 m QUAD QUAD BFW existing undulator segment BPM Remove one segment and add chicane (1.5 Å, 13.64 GeV) 3.20 m QUAD QUAD BFW 60 cm 60 cm 36cm 36cm 36cm 36cm BPM 58 cm ELEVATION VIEW e- provides 0-40 fs delay 2.6 mm crystal QUAD QUAD BFW B1 B4 B2 B3 BPM e- chicane raft 0-80 mm PLAN VIEW Beam Finder Wire |B0| ≈ 3.34 kG, R56 = 12 mm, cDt = 6 mm, hmax = 2.6 mm, q = 2.67 mrad
e- beam with dipoles ON & inserted e- & x-ray beam with dipoles retracted x-ray beam with dipoles inserted 356 mm 80 mm 2.6mm 8 mm 32 mm 0 - 80 mm alignment stage alignment stage chicane raft chicane raft existing horizontal slider motor existing girder existing girder cross-sectional view elevation view
CCD camera YAG screen (>0.3-mm thick?) vacuum window Bragg reflected x-rays f v 0.1 mm incident x-rays transmitted x-rays q crystal FEL Wavelength Range: lr = 1.4 to 1.7 Å (somewhat arbitrary) Bragg Crystal Angles :q = 51.7° (1.4 Å) to 72.4° (1.7 Å) Camera Viewing Angles: f= 2(p/2 -q) = 35.2° to 76.6° (>41°)* * Compromise: Allow camera viewing only from 1.4 to 1.6 Å or f= 77.6° to 51.4° (~27° range)
HXRSS Chicane Dipole Magnet Design is Ready • D. Walz • 0-6 A • 576 main coil turns • ±1% trim coils (±6 A) • No water cooling • ~50 W/magnet • 0.02° C tunnel rise
Possible 4-Axis Diamond Positioning System D. Shu (ANL)
Possible HXRSS Layout at U15 (or U16) Crystal chamber (ion pump must move) Sliding raft to move all 4 dipoles IN or OUT (8 cm) J. Amann (SLAC) D. Shu (ANL)
Issues • Do we place it at U15 or U16 (need ~1 GW seed)? • Will we lose power in SASE mode (25% so far)? • Can the chicane be tweaked to fix the phase error? • Is a 0-40 fs chicane OK (i.e.,only 20-40 pC supported) • OK to have 2.6-mm crystal-to-electron hor. clearance? • Commissioning plan started, but needs more thought. • Existing LCLS monochromator only measures 10-4 BW. This will have to suffice OK for now? • What will go wrong and how do we avoid it?