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Background and Forward Geometry

Background and Forward Geometry. Takashi Maruyama. Introduction. Forward region design requires a coherent design from IP to LumiCal and to BeamCal Acceptance Clearance from pairs Beam parameters Solenoid field strength 5 Tesla vs. 4 Tesla No-DID or Anti-DID Beampipe

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Background and Forward Geometry

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  1. Background and Forward Geometry Takashi Maruyama

  2. Introduction • Forward region design requires a coherent design from IP to LumiCal and to BeamCal • Acceptance • Clearance from pairs • Beam parameters • Solenoid field strength 5 Tesla vs. 4 Tesla • No-DID or Anti-DID • Beampipe • Talk about forward geometry and background constraints

  3. SiD Forward Region Cooper SiD Workshop • Very useful discussions at SLAC during IRENG07 • The general layout of forward calorimetry follows parameters provided by Bill Morse and concepts suggested by Tom Markiewicz.

  4. Current Beam pipe is designed for ILC 500 GeV Nominal + 5 Tesla 4 Tesla 5 Tesla R (cm) Z (cm) For 4 Tesla, R=1.2 cm is tight and 43 mrad is too small. R=1.4 cm and 110 mrad beam-pipe would work.

  5. Current Beam pipe is not compatibe with the Low P or High Lumi options. 500 GeV Low P + 5 Tesla 500 GeV High Lum + 5 Tesla R (cm) Z (cm) 110 mrad beam-pipe would work as long as R= 1.2 cm  1.5 cm (Low P), and R= 1.2 cm  1.8 cm (High Lumi).

  6. Neutrons from the dump x (cm) C 2.4 cm quadrupole 2.4 cm 7 mrad n 2.11010 n’s/cm2/y 3.0 cm C’ Be Si VXD W BeamCal VXD Layer 1 fluence (one beam): 1.01010 n’s/cm2/y w/o BeamCal 2.4108 n’s/cm2/y w BeamCal z (cm)

  7. IP Beampipe radius and VXD layer 1 • Rbp = 1.2 cm and Rvxd1= 1.4 cm • OK for ILC 500 GeV Nominal + 5 Tesla • Intolerable neutron fluence if the Beamcal aperture is 1.5 cm • Increase to Rbp = 1.4 cm and Rvxd1= 1.6 cm? • Will work for • ILC 500 GeV Nominal + 4 Tesla • ILC 500 GeV Low P + 5 Tesla • Neutron fluence is acceptable • Keep Rbp = 1.2 cm and Rvxd1= 1.4 cm for LOI?

  8. Pair distribution at Z = 168 cm • Beam parameters – Nominal, Low Q, High Y, Low P, High Lumi • Solenoid field strength – 5 Tesla vs. 4 Tesla • Crossing angle (14 mrad) + DID/ANTI-DID ILC 500 GeV Nominal beam parameters + 5 Tesla ANTI DID No DID Y (cm) X (cm)

  9. Pair Radius in cm at Z=168 cm Radius in black is measured from solenoid axis (x,y) = (0., 0.). Radius in red is measured from extraction line (x,y) = (-1.176 cm, 0.)

  10. Bhabha and Pairs at Z=168 cm • Anti-DID • Nominal OK • Low P OK • No DID • Nominal OK • Low P Not OK 36 mrad Y (cm) -7.22 cm 4.87 cm X (cm)

  11. SiD Beam Pipe Cooper/Krempetz

  12. Beampipe

  13. Pairs at Z = 295 cm No DID Anti-DID ILC 500 GeV Nominal R < 5 cm R < 6 cm Y (cm) ILC 500 GeV Low P R < 6 cm R < 8 cm X (cm) X (cm)

  14. Preliminary BeamCal Sensor Layout Cooper • Assumes 6” silicon sensor technology. • Wedges rotated in alternate planes for overlap. # of pads would likely be increased Beam pipes through Beam Cal may be merged to improve vacuum conductance Outgoing beam pipe Incoming beam pipe Segmentation and readout can be different for r< 7cm and r>7cm Pairs are confined within r < 6 cm.

  15. Low Z material ILC 500 GeV Nominal + DID • Low Z layer in front of BeamCal to absorb low energy e+/e- coming out of BeamCal • 10 cm thick Be (0.28X0) • Other material to absorb neutrons as well Borated Poly is more effective in absorbing neutrons but X0 is longer.

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