1. NLC - The Next Linear Collider Project Detector Design Issues:  Interaction Region David Asner/LLNL Linear Collider Retreat, Santa Cruz, June 27-29, 2002 This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48.

2. NLC - The Next Linear Collider Project Overview Is this assumption valid? Is the required detector design for  the same as e + e - ? What is different about the  IR? What is different about  interactions? Historically  physics studies assumed an ideal detector Recently, comparable performance to e + e - is assumed

3. NLC - The Next Linear Collider Project Some  Analyses in Progress s-channel higgs production –Mass measurement –Cross section x BR bb, WW*, ZZ*, Z  –MSSM deviation from SM –CP properties Heavy MSSM H 0,A 0 –Discovery –Tan , –H 0,A 0 mass splitting H + H - production –Charged higgs mass –Width, BR to extract tan    h*  hh –Higgs self coupling  H   csH + –Use polarization to measure L,R chiral couplings  squarks,sleptons  –Measure  1,  2 mass –Mixing angles –BR to sleptons,sneutrinos  W + W - –10x e + e - cross section  tt  and e + e - Physics: Similar detector performance QCD Extra-dimensions b tagging is at least as important at  Reflected in the number of studies of h  bb

4. NLC - The Next Linear Collider Project Integrating Laser Optics in  IR Essentially identical to e + e - IR 30 mRad x-angle Extraction line ± 10 mRadian Large final mirror 6cm (0.2X 0 ) thick Lucite, with central hole 7 cm radius. –Remove all material from the flight path of the backgrounds Mirror placement for LCD-Large

5. NLC - The Next Linear Collider Project 2D Interaction Region: Snowmass 2001 Cylindrical carbon fiber outer tube Vacuum boundary with transition from thick cylinder to thin beampipe. Sections of “strongback” for optical support Thermal Management

6. NLC - The Next Linear Collider Project Neutron Backgrounds (e + e - IR) The closer to the IP a particle is lost, the worse Off-energy e+/e- pairs hit the Pair- LumMon, beam-pipe and Ext.- line magnets Radiative Bhabhas & Lost beam <x10 Solutions: Move L* away from IP Open extraction line aperture Low Z (Carbon, etc.) absorber where space permits Neutrons from Beam Dump(s) Solutions: Geometry & Shielding Shield dump, move it as far away as possible, and use smallest window –Constrained by angular distribution of beamstrahlung photons Minimize extraction line aperture Keep sensitive stuff beyond limiting aperture –If VXD R min down x2 Fluence UP x40  Interaction Region Extraction line aperture is  10mRad L1 and L2 of Silicon have direct line of site to the beam dump  Greatly increased neutron flux

7. NLC - The Next Linear Collider Project Neutrons from the Beam Dump Geometric fall off of neutron flux passing 1 mrad aperture Limiting Aperture Radius (cm) z(m) # Neutrons per Year for e + e - 1.00.5 Integral Limiting aperture for  is 10mRad

8. NLC - The Next Linear Collider Project Neutron hit density in VXD NLC-LD-500 GeV e + e - NLC-LD-500 GeV  Beam-Beam pairs1.8 x 10 9 hits/cm 2 /yr expect similar Radiative Bhabhas1.5 x 10 7 hits/cm 2 /yrexpect similar Beam loss in extraction line0.1 x 10 8 hits/cm 2 /year expect similar Backshine from dump1.0 x 10 8 hits/cm 2 /yr 1.0 x 10 11 hits/cm 2 /yr TOTAL1.9 x 10 9 hits/cm 2 /yr 1.0 x 10 11 hits/cm 2 /yr Neutron Backgrounds Summary Figure of merit is 3 x 10 9 for CCD VXD Takashi Maruyama & Jeff Gronberg L1 & L2 cannot use CCD – Active Pixels?

9. NLC - The Next Linear Collider Project Summary: LD @ 500 GeV (e + e - IR)

10. NLC - The Next Linear Collider Project LD Detector Occupancies (e + e - IR) from e+e- Pairs @ 500 GeV DetectorPer bunchR. O.Eff. #B OccupancyComment VXD-L136E-3/mm 2 50  s 1485.3/ mm 2 1.5cm, 4T VXD-L23.1E-3/mm 2 250  s 7422.3/ mm 2 2.6cm, 4T TPC 1336 , 5trks55  s 160Few per mil Barrel ECAL 1176 , 0.63GeV 150 ns10.63 GeV 101  >3MeV Endcap ECAL 1176 , 1.92GeV 150 ns11.92 GeV 91  >3MeV VXD-L138E-3/mm 2 8 ms1907.2/ mm 2 1.2cm, 3T VXD-L23.1E-3/mm 2 8 ms1900.6/ mm 2 1.4cm, 3T TPC 1377 , ?trks 8 ms190“Few per mil”Needs Study Barrel ECAL 547 , 0.73 GeV 8 ms190139 GeVNeeds Study Endcap ECAL 597 , 0.9 GeV 8 ms190171 GeVNeeds Study TESLATESLA NLCNLC  requires single bunch resolution – relies on few ns TPC timing

11. NLC - The Next Linear Collider Project Time Resolution and Bunch Structure 3 Tesla TPC time res  1.4 ns =  2  bunches  95x120 Hz with 1.5x10 10 e/bunch

12. NLC - The Next Linear Collider Project Photons have Structure Three types of  collisions –Direct –Once resolved –Twice resolved Electroweak (DIS) Strong (  collider) “  ”=0.99  +.01 

13. NLC - The Next Linear Collider Project Resolved Photon Backgrounds:#1 Concern  collisions are NOT like e + e - 1.5x10 10 e - and 1x10 10  About 98% of interactions are  About 80%  *  * and 18%  * Cross section to hadronic final states is about 400nb (p t >2 MeV) Total  luminosity ~ 100 nb -1 s -1 Expect 3 - 4 underlying hadronic events per “interesting” event |cos  |<0.9 about 50 GeV, |cos  |<0.8 about 25 GeV

14. NLC - The Next Linear Collider Project Resolved Photon Background Cos  vs Energy (GeV) 85 tracks/crossing (|cos  | < 0.9) p avg = 0.6 GeV (p > 0.2 GeV)

15. NLC - The Next Linear Collider Project Conclusion  IR design requires larger aperture extraction line  10mRad –VXD L1 & L2 have direct line of site to beam dump –CCD’s cannot handle neutron flux 10 11 n/cm/y –Need to study the impact on detector performance (b-tagging) if Only have a 3 layer CCD-VXD, L3, L4 & L5 Replace L1 & L2 with active pixels All layers active pixels –Need detector design for these scenarios Radiation Summary Table for LD–500 GeV: Redo for  IR Detector Occupancy Table: Include resolved photons Simulation to assess if occupancy is low enough for pattern recognition + TPC time stamp to resolve single crossing