Beamline 12 Project BL12 In-vacuum Undulator Source August 11, 2004 Andy Ringwall BL12 In-vacuum Undulator Source August 11, 2004 Andy Ringwall

Present Spear3 9S Straight (the East Pit) UPBEAM MATCHING CELL 7.33 m Y Z, e- beam X DRIFT SPOOLS ENTRANCE MASK SUPPORTS GATE VALVE Beamline 9 on other side of wall

Double Waist Lattice and Vertical Beta Function m “Double waist” (DW) lattice proposed to replace 9S drift straight: two new ID straights and resulting beamlines m DW studies by M. Cornacchia et al.:  Low vertical beta function at the center of each straight; β = 1.6 m  Z = 1.8 m space for two undulators (1.5 m devices + approx. 0.3 m of transition length)  Focusing triplet: three quadrupoles, K values: 1.458, -1.99,  Four symmetric, 5 mrad chicane bends providing 10 mrad beamline separation  Beta function reduced from β = 9.9 m to 2.5 m in all four Spear3 matching straights 5 mrad chicane bend, 4X e-,chicane bend uses S3 style corrector Triplet This chicane kick is shown toward wall; design kick is away from wall toward Spear center

Symmetric vs. Asymmetric Chicane m Symmetric, 5 mrad bend chicane requires redesign and removal of the downbeam matching chamber: $$ risks, schedule risks, technical risk m An asymmetric bend chicane (2.0, 4.4, 14.4 & 8.0 mrad) resolves this problem and preserves 1.5 m of undulator length e- Undulator radiation, BL12 Undulator radiation, future beamline Fixed absorber Replaceable mask Exit flange, start beamline frontend

Asymmetric Chicane (Plan View), Components

m Beam “bump” studies at BL9 wiggler chamber characterized the dynamic aperture giving “conservative” and “aggressive” gaps for the new undulator; BL9 chamber has a physical aperture of 12 mm and vertical β = 4.8  Studies show an effective acceptance of mm-mrad to mm-mrad  Beta scaling (clear aperture :: β 1/2 ) to the new straights sets the required minimum gap of in-vacuum device: ã Conservative: 6.20 mm, clear aperture ã Aggressive: 4.96 mm m Assuming.40 (conservative) or.25 (aggressive) space for Cu-Ni sheets, used to reduce wall current impedance, results in pole gaps of: ã Conservative:7.0 mm = x.40 ã Aggressive:5.5 mm = x.25 m Preliminary undulator design:  λ u = 22 mm, 136 pole, Br = 1.05 (Sm-Co 2:17) ã Swiss Light Source in-vac undulator: λ u = 17, 19 mm, gap = 4.0 mm, length = 2 m  Bo = T (aggressive gap, K = 2.06);.75 T (conservative, K = 1.54) ã K =.093 λ u [mm] Bo [T]  Undulator name: U22 e- Beam Acceptance, Undulator Gap

U22 Peak Pole Field, Bo, vs. Aperture (5.0 mm, 10 kG) (6.2 mm, 7.5 kG) (20.2 mm, 0.88 kG)

Expected Undulator Performance Pole gap = 7 mm Increasing gap decreasing B 0 2.5X brightness “jump” at n=5 to n=3 crossover BL 11 wiggler brightness = 12 keV

Expected Undulator Performance Pole gap = 5.5 mm

SLS U19 As Built