Yasuhiro Sugimoto KEK Feb.4, 2008 B field and RVTX Yasuhiro Sugimoto KEK Feb.4, 2008

Baseline design for LOI Agreement in a phone meeting Two configurations 5 single layers 3 doublets Same inner and outer radii (Rout=60mm) |cosq|=0.95 for inner three layers and outer two layers have same length as the 3ed layer |cosq|=0.95 for inner two doubles and outer doublet has the same length as the 2nd doublet

Pair background simulation Generator: CAIN Crossing angle: 14 mrad B-field: 3, 3.5, and 4T Machine parameters: Nominal option in 2005 2005 parameter Recent parameter* Beta function at IP bx (m) 2.1e-2 2.0e-2 Beta function at IP by (m) 4.0e-4 4.0e-2 Beam size at IP sx (m) 6.55e-7 6.4e-7 Beam size at IP sy (m) 5.7e-9 Disruption parameter Dx 1.62e-1 1.7e-1 Disruption parameter Dy 1.85e+1 1.91+1 Beamstrahlung parameter Uave 0.046 0.047 Beamstrahlung power Pbeamstrahlung (W) 2.48e+5 2.4e+5 Number of beamstrahlung photons Ng 1.257 1.29 * Talk by Andrei Seryi at SiD Workshop at SLAC, Jan. 2008

Distribution of p.b. core

Design criteria Pair background core should not hit the beam pipe Somewhat realistic assumption for the gaps and spaces (G1, G2, L1, L2)

Results Assumption Minimum radius G1 = 2 mm G2 = 4 mm (core-pipe:2mm and pipe-ladder:2mm) L1 = 5 mm L2 = 20 mm Minimum radius 3 T 3.5 T 4 T R1 (mm) 12 11 10.5 Z1 (mm) 45 42 40 R2 (mm) 17 16 15 Z2 (mm) 76 72 68