1. Snowmass 14-7-01G. Eigen, University of Bergen G. Eigen University of Bergen Snowmass July 14, 2001

2. Snowmass 14-7-01G. Eigen, University of Bergen OUTLINE  Introduction  Silicon Vertex Detectors  Drift Chambers  DIRC  Electromagnetic Calorimeters  IFR  Trigger Rates  Examples of strawman detectors  Conclusion

3. Snowmass 14-7-01G. Eigen, University of Bergen Introduction  For precision measurements of CP-violation asymmetries and rare B decays high luminosities are an important prerequisite  Recently, the design of an e + e - storage ring  s ~ 10GeV with luminosities of £ peak = 10 36 has become feasable  So how do present subsystems of multipurpose detectors cope with the increased background levels ?  The following results are my personal views based on BABAR studies: Report of the High-Luminosity Background Task force (C. Hast, W. Kozanecki (chair), A. Kulikov, T.I. Meyer, S. Petrak, T. Schietinger, S. Robertson,M. Sullivan, J. Va’vra, BaBar Note 522)  Results for £ peak ≥ 10 35 should be taken with a grain of salt:  Extrapolations are made over > 2 orders of magnitude (errors > factor 2)  Extrapolations depend very much on IR layout

4. Snowmass 14-7-01G. Eigen, University of Bergen Background Issues  Acceptable levels of backgrounds are determined by  Radiation hardness of subdetectors  inefficiencies, destruction  Trigger rate  deadtime, loss of signal  Detector occupancies  inefficiencies, worse resolution, worse S/B  Occupancy and trigger rate determine acceptable dynamic running conditions  Total integrated radiation dose determines lifetime of subdetectors  Dose is accumulated under normal running conditions, during injection, machine studies and beam-loss events  At PEP II dose accumulated during running dominates  At £ peak = 10 36 machine this is different, injection losses determine dose

5. Present Measures of BABAR Subsystems to Machine Backgrounds  Radiation Hardness of SVT detector modules is estimated at 2MRad Instantaneous dose rate in radiation protection diodes BW:MID & FE:MID are within factor of two representative of harshest radiation levels hitting SVT modules in horizontal plane  Total current drawn by drift chamber is limited to 1000  A by existing HV power supplies  Counting rate above 200-300 kHz in DIRC phototubes starts inducing significant dead time with present electronics  Fractional EMC crystal occupancy above a 1 MeV threshold and number of crystals above 10 MeV characterize potential degradation of calorimeter energy resolution, as well as number of fake neutral clusters  Level-1 (L1) trigger rate is currently limited to 2.0-2.5 kHz by DAQ bandwidth considerations

6. Snowmass 14-7-01G. Eigen, University of Bergen Present Sources of Machine Backgrounds  Detector subsystems are subjected to different machine-related backgrounds  Electrons:  lost particles backgrounds (beam-gas bremsstrahlung,  Coulomb scattering) and synchrotron radiation  Positrons:  lost particles backgrounds (beam-gas bremsstrahlung)  2 beams:  no collision  single beam backgrounds above plus beam-gas cross term  in collision  backgrounds from luminosity, beam-beam tails & above 3  Note that there is a difference in operation between PEP II at high £ peak & an  £ peak = 10 36 collider:  PEP II: inject & run (stable beams)   continuous injection (no stable beams)

7. Snowmass 14-7-01G. Eigen, University of Bergen Backgrounds in PEP II & in an L=10 36 Machine  Background estimates by W. Kozanecki based on J. Seeman’s design PEP II 10 36  Beam loss rates in PEP II and a 10 36 machine differ by a factor of > 10 3 but only small fraction will contribute to detector backgrounds HER LER Super HERSuper LER Beam current I b [A]0.71.45.520.5 Beam lifetime  b [min] 5501504.23.2 Beam loss rate I b /  b Luminosity [A/min]0.370.35 Vacuum [A/min]0.060.68 Touschek [A/min]0.062.28 b-b tune shift [A/min]0.552.05 Dynamic aperture [A/min]0.281.03 Total [A/min] 1.3  10 -3 9.3  10 -3 1.326.39

8. Snowmass 14-7-01G. Eigen, University of Bergen Backgrounds in an L=10 36 Machine  In PEP II LER lifetime is dominated by vacuum or Touschek effect, while HER lifetime is affected by beam-beam tune shift and then vacuum  Background sources in SVT, DCH and EMC result from beam-gas in the incoming straight section  Beam-beam tune shifts, dynamic aperture and vacuum losses probably will contribute to vacuum-like backgrounds, since losses are transverse (like distant LER Coulomb scattering in PEP II)  Since quads need to be shielded transverse losses are produced at betatron collimators far from IP  combined transverse losses are main issue with LER backgrounds only 15%-20% of them, HER is minor problem  Effects of longitudinal losses at £ peak = 10 36 are not known, since these have not been studied in PEP II  Since sum of longitudinal, all transverse and injection losses is so large, vacuum in IR will be less a problem, still need pressure of 10 -9 within 50m of IP

9. Snowmass 14-7-01G. Eigen, University of Bergen Dependence of backgrounds on beam currents  Touschek: Dependence is not known, expect no effect for a while (low I LER, long Touschek lifetime, negligible secondary particles) At some point it will take off  need simulation with Turtle  Beam-beam tune shift: very non-linear and very tune sensitive  Dynamic Aperture: linear (?)  Vacuum: quadratic in I LER (the base pressure will be well-controlled, the dynamic pressure will dominate)  Luminosity: linear in beam currents

10. Snowmass 14-7-01G. Eigen, University of Bergen Estimates of backgrounds due to beam losses  Touschek: Need Turtle-like simulation of energy spectrum  Tranverse losses: Scale distant Coulomb prediction by the ratio of loss rates with measured distant LER-only contributions (DCH,DIRC)  Injection losses: Take clean injection day from PEP II and scale by injection currents  Secondary particles: Due to multistage injection, betatron collimation and momentum collimation secondary particles are big issue realistic simulation is a major task  Radiative Bhabha: Debris in the detector from radiative Bhabhas eventually will become large, it is sensitive to beam line geometry & IR layout  Caution: In extrapolations below none of above effects is included

11. Multipurpose Detector for e+e-Collisions at 10GeV

12. Snowmass 14-7-01G. Eigen, University of Bergen Luminosity Considerations  For luminosities shown in blue extrapolations have been taken from the report of the High-Luminosity Background Task force, while for luminosities shown in green results are my extrapolations using the algorithms given by the High-Luminosity Background Task force Date£ peak [cm -1 s -1 ] June 2002 6.5  10 33 August 2005 1.5  10 34 2008 ? 5.0  10 34 ? 1.0  10 35 1.0  10 36

13. Snowmass 14-7-01G. Eigen, University of Bergen Silicon Vertex Trackers

14. Snowmass 14-7-01G. Eigen, University of Bergen Dose accumulated in BABAR SVT

15. Snowmass 14-7-01G. Eigen, University of Bergen SVT Radiation Dose in Middle Plane time SVT dose rate [krad/y] 2  10 33 10 34 5 10 35 5 10 36 FE MID BW MID  SVT dose rate: FE MID [kRad/y] =128 I LER + 16 I 2 LER BW MID [kRad/y] =246 I HER + 9.1 I 2 HER  In top & bottom planes dose rate is ~ factor of 10 lower than in middle plane

16. Snowmass 14-7-01G. Eigen, University of Bergen Silicon Vertex Detector Occupancy

17. Snowmass 14-7-01G. Eigen, University of Bergen Conclusion on Silicon Vertex Detectors  Radiation levels depend very strongly on IR layout, (KEKB < PEP II)  In BABAR silicon detectors are expected to survive a total dose of 2MRad  With replacements of detectors in the MID plane BABAR SVT is expected to survive luminosities of 1.5-3  10 34  LHC R&D demonstrated that Si detectors can survive high irradiation H. Yamamoto bonded 150  thick pixels (55   55  ) (CMOS)  At £ peak ~ 1  10 36 occupancy is an issue for Si strip detectors close to IR  pixels in first two layers  So for £ peak ~ 1-10  10 35 appropriate silicon detectors probably work £ peak [cm -1 s -1 ] 6.5  10 33 1.5  10 34 5  10 34 1  10 35 1  10 36 ∫£dt [fb -1 ]/y 65150500100010000 I LER/ I HER [A]2.8/1.13.7/1.34.6/1.59/2.518/5.5 D SVT [kRad/y]480/280690/ 3401300/4702450/6707490/1630

18. Snowmass 14-7-01G. Eigen, University of Bergen Drift Chambers

19. Snowmass 14-7-01G. Eigen, University of Bergen  Machine backgrounds affect operation of Drift Chamber in 3 ways:  Total current I DCH in Drift Chamber drawn by wires is dominated by charge of beam-related showers I DCH is limited by high-voltage system,  above limit chamber becomes non operational!  high currents also contribute to aging of chamber!  maximum Q max: 0.1-1.0 Cb/cm of wire  Occupancy in Drift Chamber due to backgrounds (hits, tracks) can hamper reconstruction of physics events  Ionization radiation can permanently damage read-out electronics & digitizing electronics Drift Chambers

20. Snowmass 14-7-01G. Eigen, University of Bergen Drift Chamber Currents  I DCH [  A] = 35.3 I LER +23.5 I 2 LER + 77.2 I HER +46.3 I 2 HER + 41.9 £ -14 with currents in [A] and luminosity in units of [10 33 cm -1 s -1 ]  Single beam and collision measurements taken June/ July at HV=1900V  For HV=1960V scale current by factor 1.67

21. Snowmass 14-7-01G. Eigen, University of Bergen Measured Drift Chamber Currents & Models  Single-beam measurements (LER) taken with BABAR DCH in June and July 2000 at HV=1900V

22. Snowmass 14-7-01G. Eigen, University of Bergen Drift Chamber Backgrounds  Extrapolation for HV=1900V  At HV=1960 background levels are expecetd to be 65% higher time total DCH current [  A] 2  10 33 10 34 5 10 35 5 10 36 Luminosity I LER I HER

23. Snowmass 14-7-01G. Eigen, University of Bergen Drift Chamber Occupancy  N DCH = 0.044+0.191 I LER +0.0402 I 2 LER + 1.03 I HER +0.113 I 2 HER + 0.147 £ with occupancy in [%], currents in [A], luminosity in units of [10 33 cm -1 s -1 ] at 1900V  At HV=1900V (Jan-July): N DCH = 158+0.27 I DCH (<350  A)  At HV=1960 V(July-now): N DCH = 203+0.18 I DCH (>200  A)  Large spread  extrapolation difficult data points at ~ same £

24. Snowmass 14-7-01G. Eigen, University of Bergen Drift Chamber Occupancy  Extrapolation for HV=1900V time DCHoccupancyt [%] 2  10 33 10 34 5 10 35 5 10 36 Luminosity I LER I HER  N DCH = 0.044+0.191 I LER +0.0402 I 2 LER + 1.03 I HER +0.113 I 2 HER + 0.147 £

25. Snowmass 14-7-01G. Eigen, University of Bergen Conclusion on Drift Chambers  Total dose depends on ∫£dt: at 20 fb -1 accumulated 100 rads  For £ peak > 1  10 35 it is very unlikely that drift chambers will work One needs other devices: straws, TPC with GEM readout, Si tracker £ peak [cm -1 s -1 ] 6.5  10 33 1.5  10 34 5  10 34 1  10 35 1  10 36 ∫£dt [fb -1 ]/y 65150500100010000 I LER/ I HER [A]2.8/1.13.7/1.34.6/1.59/2.518/5.5 I DCH [  A] 6801250 3370688051960 N DCH [%]3.1 5 1223173 Q wire [mCb]~15 361002002000

26. Snowmass 14-7-01G. Eigen, University of Bergen GEM Layout

27. Snowmass 14-7-01G. Eigen, University of Bergen GEM Layout

28. Snowmass 14-7-01G. Eigen, University of Bergen DIRC PARTICLE IDENTIFICATION

29. Snowmass 14-7-01G. Eigen, University of Bergen Composition of DIRC Background time DIRC occupancy [ kHz] 2  10 33 10 34 5 10 35 5 10 36  N DIRC [kHz] = 35 I LER + 8.5 I HER + 25 £ total I LER I HER

30. Snowmass 14-7-01G. Eigen, University of Bergen Conclusion on DIRC  BABAR DIRC is ok up to £ peak =6  10 34, however the water tank provides a huge Cherenkov detector  At high luminosities £ peak >1  10 35 another approach is needed: a compact readout using focussing or timing £ peak [cm -1 s -1 ] 6.5  10 33 1.5  10 34 5  10 34 1  10 35 1  10 36 ∫£dt [fb -1 ]/y 65150500100010000 I LER/ I HER [A]2.8/1.13.7/1.34.6/1.59/2.518/5.5 N DIRC [kHz]270 516 1470284025700

31. Snowmass 14-7-01G. Eigen, University of Bergen Different DIRC Imaging Methods  Note that different imaging methods can be chosen in each space dimension

32. Snowmass 14-7-01G. Eigen, University of Bergen DIRC Readout  B. Ratcliff

33. Snowmass 14-7-01G. Eigen, University of Bergen Separation Performance vs Random Rates

34. Snowmass 14-7-01G. Eigen, University of Bergen ELECTROMAGNETIC CALORIMETER

35. Snowmass 14-7-01G. Eigen, University of Bergen Average Occupancy in EMC Crystals  N EMC (E> 1MeV)= 9.8 + 2.2 I HER +2.2 I LER + 1.4 £ N EMC (E> 10MeV)= 4.7 I HER + 0.23 I 2 HER +2.4 I LER + 0.33 I 2 LER + 0.6 £ with beam currents in units of [A] and luminosity in units of [10 33 cm -1 s -1 ] Single Crystal occupancy # Crystals with > 10 MeV

36. Snowmass 14-7-01G. Eigen, University of Bergen Light Yield Changes in EMC

37. Snowmass 14-7-01G. Eigen, University of Bergen Worst Dose Rate in EMC

38. Snowmass 14-7-01G. Eigen, University of Bergen Effect of Background on  0 Reconstruction  Background photons both increase  0 background levels and degrade mass resolution

39. Snowmass 14-7-01G. Eigen, University of Bergen time 2  10 33 10 34 5 10 35 5 10 36 Composition of EMC Backgrounds EMC occupancyt [%] time # EMC crystals  > 10 MeV total I LER I HER 2  10 33 10 34 5 10 35 5 10 36  > 1 MeV  N EMC (E> 1MeV)= 9.8 + 2.2 I HER +2.2 I LER + 1.4 £ N EMC (E> 10MeV)= 4.7 I HER + 0.23 I 2 HER +2.4 I LER + 0.33 I 2 LER + 0.6 £ total I LER I HER noise

40. Conclusion on Electromagnetic Calorimeters  For luminosities < 1.5  10 34 integrated radiation dose for CsI(Tl) crystals is not expected to be a problem if observed light losses scale as expected  Impact of large number of low-energy photons on EMC energy resolution depends on clustering algorithm, digital filtering, etc (needs further study) Expect luminosity contribution to be dominant  Expect reduction of background rates through improvements of vacuum near IR combined with effective collimation against e+ from distant Coulomb scattering  For luminosities >1  10 35 light loss due to radiation and occupancy levels for present CsI(Tl) crystals are not acceptable  need R&D studies and look into other scintillator (pure CsI, LSO, GSO?) £ peak [cm -1 s -1 ] 6.5  10 33 1.5  10 34 5  10 34 1  10 35 1  10 36 ∫£dt [fb -1 ]/y 65 150500100010000 I LER/ I HER [A]2.8/1.13.7/1.34.6/1.59/2.518/5.5 N EMC [%]2842931751460 N cluster 21 3256122783

41. Snowmass 14-7-01G. Eigen, University of Bergen Properties of Scintillating Crystals

42. Snowmass 14-7-01G. Eigen, University of Bergen INSTRUMENTED FLUX RETURN

43. Snowmass 14-7-01G. Eigen, University of Bergen Conclusion on IFR  Main issue is high occupancy in outer layers due to beam-related backgrounds  Presently outer RPC layer has random occupancy of several %  At design currents and at higher luminosity this will become an unacceptably high contribution to  /  misidentification  Solution for £ peak ~ 3-5  10 34 : build 5 cm thick Fe shield following outer-most chamber  At £ peak > 1  10 35 occupancy becomes an issue despite shielding RPC’s are not suited, replace them with scintillating fibers

44. Snowmass 14-7-01G. Eigen, University of Bergen TRIGGERS

45. Snowmass 14-7-01G. Eigen, University of Bergen L1 Trigger Rate vs Current in Machine

46. Snowmass 14-7-01G. Eigen, University of Bergen Trigger Rates time Total trigger rate [Hz] 2  10 33 10 34 5 10 35 5 10 36 Total (L) I HER I LER Background  Expected L1 trigger rate: L1 [Hz]=130 (cosmics)+ 130 I LER + 360 I HER + 70 £

47. Snowmass 14-7-01G. Eigen, University of Bergen Extrapolation on Trigger Rates  For £ peak ~1.5  10 34 in BABAR trigger needs to be upgraded to cope with high rates  For higher luminosities one could do more stringent prescaling of Bhabhas, radiative Bhabhas, beam gas, (want to keep all b, c decays) One needs to design appropriate tracking device used in trigger  LHC experiments can accept L1 trigger rates of 100 kHz (ATLAS) bunch crossing is 40 MHz £ peak [cm -1 s -1 ] 6.5  10 33 1.5  10 34 5  10 34 1  10 35 1  10 36 ∫£dt [fb -1 ]/y 65 150500100010000 I LER/ I HER [A]2.8/1.13.7/1.34.6/1.59/2.518/5.5 L1 [Hz] 1350 21304800920074500

48. Snowmass 14-7-01G. Eigen, University of Bergen Trigger for High Luminosity Machine

49. Snowmass 14-7-01G. Eigen, University of Bergen Trigger for High Luminosity Machine

50. Detector Considerations  The angular acceptance is limited by beam focussing elements to 300mr  By keeping present boost  =0.58 and a resolution improved by a factor of two one needs to move closer to IP  1cm gold-plated Be beam pipe  To cope with occupancy problems near IR, use Si pixel detectors for first 2 layers of vertex detector, 3 layers Si strip detectors  For central tracker consider either all Si strips, straw tubes or TPC with GEMs readout  For particle identification consider Super DIRC  For EMC consider scintillating crystal calorimeter based on pure CsI, LSO or GSO  For IFR use Fe plates read out with scintillating fibers  Strawman designs resulted in discussions in breakout sessions: G. Dubois-Felsman, G. E., M. Giorgio, D. Hitlin, X. Lou, D. Leith, E. Paoloni, I. Peruzzi, M. Piccolo, M. Sokoloff, H. Yamamoto

51. Snowmass 14-7-01G. Eigen, University of Bergen Modified Multipurpose Detector TPC with GEMs ECs or strawtubes Pure CsI with APD’s readout Compact DIRC IFR with scintillating fibers First 2 layers pixels +3 layers Si strips

52. Snowmass 14-7-01G. Eigen, University of Bergen Compact Multipurpose Detector SVT 2 Ly pixel 3 Ly Si strip 4 Ly Si strip tracker Compact DIRC LSO EMC 3T Coil IFR Fe + scint. fibers

53. Snowmass 14-7-01G. Eigen, University of Bergen Conclusions  Vertex detectors:  Based on studies at LHC silicon vertex detectors probably will work at high luminosties of £ peak ~ 1-10  10 35, need pixel detectors in first two layers (  R & D)  Central tracker:  For £ peak > 1  10 35 it is very unlikely that drift chambers will work Need to consider an all Si strip tracker, straw tubes or TPC/GEMs  Particle ID:  With appropriate design of accepted counting rates, beam collimation & shielding a compact DIRC probably will work at £ peak ~ 1-10  10 35  Electromagnetic Calorimeter:  For £ peak >1  10 35 light loss due to radiation and occupancy levels for present CsI(Tl) crystals are not suitable explore other scintillators (pure CsI, LSO, GSO,…) (  need R&D)  Trigger:  It should be possible to design trigger system for £ peak = 1  10 36

54. Snowmass 14-7-01G. Eigen, University of Bergen Silicon Vertex Detectors

55. Snowmass 14-7-01G. Eigen, University of Bergen L1 Trigger Rate vs Current in Machine

56. Snowmass 14-7-01G. Eigen, University of Bergen Drift Chamber Currents

57. Snowmass 14-7-01G. Eigen, University of Bergen Average Occupancy in EMC Crystals Single Crystal occupancy # Crystals with > 10 MeV  N EMC (E> 1MeV)= 9.8 + 2.2 I HER +2.2 I LER + 1.4 £ N EMC (E> 10MeV)= 4.7 I HER + 0.23 I 2 HER +2.4 I LER + 0.33 I 2 LER + 0.6 £ with beam currents in units of [A] and luminosity in units of [10 33 cm -1 s -1 ]