1. Guy Wormser, Super B-Factory Workshop, Jan 04 1 Current Background Situation in BaBar “Always a concern, often an issue but never a showstopper” zThe background sources: (Synchrotron Radiation), Beam-Gas, Radiative Bhabbas, Beam-Beam effects, Radiation bursts, Injection, (Touscheck) zThe background effects: integrated dose, instantaneous damage, operational issues, data quality zThe background remediation strategy Babar protection system, budget policy, forward looking to bottlenecks using projection and simulations z Today’s questions yTrickle injection yInjection quality yPreparation for tomorrow z Conclusion

2. Guy Wormser, Super B-Factory Workshop, Jan 04 2 The background sources zSynchrotron radiation : very well masked, has never been a problem for BABAR zBeam-Gas : BABAR sees debris from electromagnetic showers of scattered electrons and photons. yTwo subcomponents : Brems and Compton scattering yWell described by simulation yEfficient collimator scheme

3. Guy Wormser, Super B-Factory Workshop, Jan 04 3 The background sources (2) zRadiative Bhabbas yShowers debris from off-energy electrons or positrons after Bhabbas scattering swept away by magnetic elements in interaction regions zBeam-beam effects z« Trapped/Dust events » (HER specific) zTouschek effects : not observed yet

4. Guy Wormser, Super B-Factory Workshop, Jan 04 4 Predictability score zPredictables sources ySynchrotron yBeam gas xBremstralhung xCompton yTouschek zIn principle predictable source yRadiatvie Bhabbas zUnreliably predictable sources yBeam-beam yElectron cloud effects yInjection doses zUnpredictable sources yRadiation bursts, “dust events”

5. Guy Wormser, Super B-Factory Workshop, Jan 04 5 Agressive PEP-II plans Can BABAR keep up? Present headroom limited! Historically, the same challenge has always been met!

6. Guy Wormser, Super B-Factory Workshop, Jan 04 6 Background parametrization based on February 2002 data The observed background is roughly twice larger than the sum of the single beam contributions

7. Guy Wormser, Super B-Factory Workshop, Jan 04 7 DCH background history M. Kelsey

8. Guy Wormser, Super B-Factory Workshop, Jan 04 8 Serious problem in DCH readout if nothing is done

9. Guy Wormser, Super B-Factory Workshop, Jan 04 9 Remediation and Forward looking of bottlenecks zExample of DIRC TDC y In 1999, we predicted that the single rate PMT in the DIRC would in 2002-2003 exceed the 200 kHz limit yA lot of effort to improve the shiedling yLaunch design of a new TDC, implemented in summer 2002 with a 2 MHz capability. yThe 200 kHz limit was indeed reached in fall 2002 zNext on line: DCH read out!

10. Guy Wormser, Super B-Factory Workshop, Jan 04 10 DIRC main source of background: Radiative Bhabhas striking Q4 magnet inboard flange z Source discovered empirically with a Geiger counter. z Shielding erected step-by-step slowly building empirically a proof that things are improving. z A final shield erected in 2001, and the whole job completed in 2002. z Carsten proved later, with a Turtle program, that a major source of DIRC background is the radiative Bhabhas striking Q4 inboard flange, which is too small.

11. Guy Wormser, Super B-Factory Workshop, Jan 04 11 IFR issues zIFR is the only BABAR subdetector where the existing hardware capabilities are presently significantly degraded because of background: Layers 13, 15,16 turned off in the forward endcap (loss of factor ~2 in the mu/pi rejection in that region) IFR background comes losses near collimator BSC3042 which is very sensitive to beam-beam effects and thus very useful to the rest of BABAR… Must provide a shielding wall (summer 2004)

12. Guy Wormser, Super B-Factory Workshop, Jan 04 12 IFR issues

13. Guy Wormser, Super B-Factory Workshop, Jan 04 13 IFR and beam loss monitor

14. Guy Wormser, Super B-Factory Workshop, Jan 04 14 SVT Background from HER (BW:MID) Moves toward half-integer HER sensitive SVT module (Does not have threshold shift problem): Background almost doubled after move to half-integer Again it has come down a bit during run-4 Note peak occupancy is 150% higher than average occupancy! For occupancies in all SVT modules, see: http://www.slac.stanford.edu/~babarsvt/SectionOccupancies.ps

15. Guy Wormser, Super B-Factory Workshop, Jan 04 15 SVT rates in 2003 compared to 2002 extrapolation

16. Guy Wormser, Super B-Factory Workshop, Jan 04 16 Single beam and lumi sensitivity HERHER **2 LERLER* *2 Lumi SVT( mid) XY0 DCH1103025752 DRC13018010 EMC2.20 01.4

17. Guy Wormser, Super B-Factory Workshop, Jan 04 17 MID Plane Doses Stable beam contribution of FW:MID and BW:MID is overestimated Run 3+4 dose is 40- 60% of Run1+2 Luminosity is 55% of Run1+2 Damage in SVT modules starts

18. Guy Wormser, Super B-Factory Workshop, Jan 04 18 TOP Doses Dominated by injection dose (up to 90%) Getting HER to “trickle quality” would provide large gains

19. Guy Wormser, Super B-Factory Workshop, Jan 04 19 Summary of Detector sensivities and main issues zSVT : Integrated Dose, Occupancy, single beam and beam-beam, FE electronics strange effects zDCH : Readout capabilities, radiative Bhabbas zDIRC : No problem for now, radaitive Bhabbas zEMC Integrated dose in Endcap for the long term, leakage current in Diodes (neutrons?), occupancy, zIFR Single rate for external layers, beam-beam effects zSVTRAD : integrated dose, will need to be replaced soon zIntegrated dose: SVT 2Mrad in the most exposed regions, EMC 1 krad in the most exposed regions zRather similar to what BELLE received ?

20. Guy Wormser, Super B-Factory Workshop, Jan 04 20 MID Dose Rates until 2009 Use Seeman model for beam currents to predict dose rates: Dose rates do not looking forbiddingly high Rates peak at roughly the current soft abort limits - DQ should still be reasonable

21. Guy Wormser, Super B-Factory Workshop, Jan 04 21 Midplane Doses until 2009 Module exchange in 2005 looks well timed with 4 Mrad budget One rotation in 2007 should be able to keep MID modules installed in 2005 below 5 Mrad A rotation will move the high dose in FE:MID to other module

22. Guy Wormser, Super B-Factory Workshop, Jan 04 22 BABAR scorecard July 2004

23. Guy Wormser, Super B-Factory Workshop, Jan 04 23 BABAR scorecard July 2006

24. Guy Wormser, Super B-Factory Workshop, Jan 04 24 Dose in calorimeter

25. Guy Wormser, Super B-Factory Workshop, Jan 04 25 BABAR scorecard 2009

26. Guy Wormser, Super B-Factory Workshop, Jan 04 26 Data quality issues in SVT

27. Guy Wormser, Super B-Factory Workshop, Jan 04 27 Resolution degration with occupancy

28. Guy Wormser, Super B-Factory Workshop, Jan 04 28 Example in

29. Guy Wormser, Super B-Factory Workshop, Jan 04 29 HER Injection Problems

30. Guy Wormser, Super B-Factory Workshop, Jan 04 30 Characterization of injection aborts/inhibits BP / LP + ODF

31. Guy Wormser, Super B-Factory Workshop, Jan 04 31 A variety of fast radiation spikes (stored beams) B. Petersen G. Wormser

32. Guy Wormser, Super B-Factory Workshop, Jan 04 32 A variety of fast radiation spikes (stored beams) B. Petersen G. Wormser

33. Guy Wormser, Super B-Factory Workshop, Jan 04 33 Run 4 Trip Summary Average of 4 trips/day – Run 3 average was 3 trips/day Last two weeks average is down to almost 1 trip/day Only one other abort looked suspicious A couple of aborts are due to broken thermistor

34. Guy Wormser, Super B-Factory Workshop, Jan 04 34 Some exemple of « Dust events »

35. Guy Wormser, Super B-Factory Workshop, Jan 04 35 Trickle solved top of fill beam_beam effects

36. Guy Wormser, Super B-Factory Workshop, Jan 04 36 Revided simulation efforts zLocations of the sources of Lumi terms and possible shielding zImprovment of collimators locations zValidation of new IR design

37. Guy Wormser, Super B-Factory Workshop, Jan 04 37 Evidence for neutron radiation? zDiode leakage current in EMC read-out zIFR background ? zJ. Vavra developped a neutron detector very insensitive to photons that will be placed shortly along the beam pipe

38. Guy Wormser, Super B-Factory Workshop, Jan 04 38 Conclusions for short term issues zWe have to look far ahead: Minimum 3 years zLook for worst case scenarios! zLook for end-product effects! zBABAR issues yImmediate concerns: SVT ATOM chip, IFRForward endcap yNext on-line: DCH DAQ yLonger term issues: SVT and EMC in 2008 zChanges in background issues yBeam-beam tails yinjections ytrapped events

39. Guy Wormser, Super B-Factory Workshop, Jan 04 39 Background issues for a Super B factory zDetector has to stay always on! z Detector Protection system : can we get rid of it? If not, it has to stand 100 MRad yAvoid all detector susceptible to instantaneous damage zOnce proper rad hard technology has been chosen, occupancy will become the next major issue : ultra fast and hyper-segmented

40. Guy Wormser, Super B-Factory Workshop, Jan 04 40

41. Guy Wormser, Super B-Factory Workshop, Jan 04 41 BABAR scorecard today X: visible effect with non-zero impact - : visible effect with no impact ? : yet unknown fixed: det upgrade to fix a significant issue x(trickle)