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B field and RVTX

Yasuhiro Sugimoto

KEK

Feb.4, 2008

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Baseline design for LOI

Agreement in a phone meeting Two configurations

5 single layers 3 doublets

Same inner and outer radii (Rout=60mm) |cos|=0.95 for inner three layers and outer two la

yers have same length as the 3ed layer |cos|=0.95 for inner two doubles and outer doubl

et has the same length as the 2nd doublet

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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 x (m) 2.1e-2 2.0e-2

Beta function at IP y (m) 4.0e-4 4.0e-2

Beam size at IP x (m) 6.55e-7 6.4e-7

Beam size at IP y (m) 5.7e-9 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 N 1.257 1.29

* Talk by Andrei Seryi at SiD Workshop at SLAC, Jan. 2008

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Distribution of p.b. core

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Design criteria

Pair background core should not hit the beam pipe Somewhat realistic assumption for the gaps and

spaces (G1, G2, L1, L2)

Core of Pair-Background

L2

G2

L1

G1

Si waferBeam Pipe

R2

Z2

R1

Z1

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Results

Assumption 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