1. Overview of the KOPIO Detector 2005 RHIC & AGS Users ’ Meeting Brookhaven National Laboratory June 20, 2005 David E. Jaffe

2. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting2 Poor kinematic signature: 3-body decay Neutral initial and final states Only outgoing  0  is observable SM prediction Br(K L  0 ) = 3x10 -11 Main background is K L  0  0 with Br=9.3x10 -4 which implies a need for suppression of >7x10 7 Observing K L  0 “Experimentally, the problems are perhaps best represented by the statement that nobody has shown that a measurement of this decay is absolutely impossible” F.J.Gilman, “CP violation in Rare K Decays”, Blois CP Violations 1989:481-496

3. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting3 Experimental Search for K L  0 E391a using same technique and is the first dedicated experiment to search for K L  0 KTeV Results using ‘pencil’ beam PL B447(1999)240.

4. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting4 KOPIO technique: work in K L CMS Measure everything possible Microbunched K L beam Measure  directions in PR Measure  energy in CAL Reconstruct  0 from  Measure K L velocity from TOF Photon Veto (PV) Charged Particle Veto (CPV) Kinematic veto

5. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting5

6. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting6 KOPIO technique: work in K L CMS Measure everything possible Microbunched K L beam Measure  directions in PR Measure  energy in CAL Reconstruct  0 from  Measure K L velocity from TOF Photon Veto (PV) Charged Particle Veto (CPV) Kinematic veto

7. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting7 Microbunch Width 93 MHz cavity at 22 kV gave  = 240 ps  Microbunch time, in ns 93 MHz cavity at 22 kV gave  217 ps  Microbunch time, in ns DataSimulation Data Simulations predict  = 180ps utilizing new 25 and 100MHz cavities

8. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting8 Interbunch Extinction 4.5 MHz cavity at 130 kV gave  = 8 (+/- 6) x 10 -6 Microbunch time, in ns Data Simulation 4.5 MHz cavity at 130 kV gave  = 1.7 (+/- 0.9) x 10 -3. DataSimulation Interbunch events Interbunch events Extinction performance at high AGS intensities last remaining issue to be verified

9. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting9 KOPIO technique: work in K L CMS Measure everything possible Microbunched K L beam Measure  directions in PR Measure  energy in CAL Reconstruct  0 from  Measure K L velocity from TOF Photon Veto (PV) Charged Particle Veto (CPV) Kinematic veto

10. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting10 Extruded Scintillator & WLS fibers Cathode strip drift chambers................  e+e+ e-e- Preradiator – convert & measure  properties 64 Layers (4% X 0 /layer, 2.7 X 0 ) 256 Chambers 288 Scintillator Plates (1200 m 2) 150,000 Channels Readout 4m

11. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting11 KOPIO technique: work in K L CMS Measure everything possible Microbunched K L beam Measure  directions in PR Measure  energy in CAL Reconstruct  0 from  Measure K L velocity from TOF Photon Veto (PV) Charged Particle Veto (CPV) Kinematic veto

12. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting12 Shashlyk Photon Calorimeter APD Shashlyk modules prototyped and tested in beams. Required specs have all been met

13. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting13 KOPIO technique: work in K L CMS Measure everything possible Microbunched K L beam Measure  directions in PR Measure  energy in CAL Reconstruct  0 from  Measure K L velocity from TOF Photon Veto (PV) Charged Particle Veto (CPV) Kinematic veto

14. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting14 Every detector is a photon veto! Fine-sampling lead/scintillator-basedshower counters of shashlyk & bar geometry. All thick enough so punch-through not an issue. KOPIO PV estimates and simulations based on BNL E949 measurements supplemented by FLUKA calculations 1 MeV Visible Energy Threshold

15. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting15 Catcher: Hadron Blind Beam  Veto beam 420 modules of Pb-Aerogel counter

16. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting16 KOPIO technique: work in K L CMS Measure everything possible Microbunched K L beam Measure  directions in PR Measure  energy in CAL Reconstruct  0 from  Measure K L velocity from TOF Photon Veto (PV) Charged Particle Veto (CPV) Kinematic veto

17. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting17 Plastic Scintillator – backed up by  vetoes! 185 290 10 -5 10 -4 10 -3 Data MC Charged Particle Veto Performance 10 -6

18. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting18 KOPIO technique: work in K L CMS Measure everything possible Microbunched K L beam Measure  directions in PR Measure  energy in CAL Reconstruct  0 from  Measure K L velocity from TOF Photon Veto (PV) Charged Particle Veto (CPV) Kinematic veto

19. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting19 Kinematic Separation of Signal &Backgrounds SignalBackgrounds Pion kinetic energy squared (T *2 ) vs Ln(Missing Energy)

20. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting20 Discovering/Constraining New Physics 1 st yr 2 nd yr 3 rd yr KOPIO Proposal

21. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting21 Only approved experiment sensitive enough reach the SM level Uses a robust innovative technique to suppress background Only experiment that measures the area of the unitarity triangle Excellent discovery potential for non-SM physics KOPIO is Unique

22. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting22 Extras

23. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting23 BNL scientists and KOPIO BNL physics dept scientists currently participating on KOPIO D.Beavis: Integration SSM,Vacuum,CDR J.Frank : CPV STL, CPV construction D.Jaffe : Sim. SSM, Parameters STL, CDR, 2 students/2004,1 student/2005 S.Kettell: Trig/DAQ/Offline/FEE STL, Trigger L.Littenberg: Spokesman,CDR,1student/2004,1student/2005 G.Redlinger: DAQ SSM,CDR,PV ineff’y,1student/2004 C.Scarlett:CDR,1student/2004,2students/2005 M.Sivertz:AGS SSM,CAL/PV STL, CDR, CPVconstruction, microbunch testbeam,2students/2004,1student/2005 STL=Scrub Team Leader for Apr05 NSF review CDR=author of chapter(s) in KOPIO Conceptual Design Report for Apr05 NSF review

24. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting24 The Challenge of KOPIO B(K L  0 ) ~ 3  10 -11, need huge flux of K’s –rates inevitably rather high Kinematic signature weak (2 particles undetectable) Backgrounds with  0 up to 10 10 times larger Veto inefficiency on extra particles must be  10 -4 Huge flux of neutrons in beam –can make  0 off residual gas – require high vacuum –halo must be very small –hermeticity requires photon veto in this beam Need convincing measurement of background _

25. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting25 KOPIO Technique High intensity micro-bunched beam from the AGS Measure everything! (energy, position, angle, time) Eliminate extra charged particles or photons –KOPIO:  0 inefficiency < 10 -8 Suppress backgrounds –Predict backgrounds from data:dual cuts –Use “blind” analysis techniques –Test predictions “outside the box” Weight candidate events with S/N likelihood function

26. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting26 Proton Beam 100TP/spill (upgraded from present 70TP) ~5s spill, 2.3s interspill Microbunching Extract debunched beam resonantly between empty buckets 25MHz frequency 200ps bunch width 10 -3 interbunch extinction Kaon Beam 42.5 o take-off angle Soft momentum spectrum 0.5-1.5 GeV/c 3  10 8 K L /spill 8% decay 10 GHz neutrons Need AGS to provide 40 ns between microbunches  =200 ps

27. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting27 Extruded Scintillator & WLS fibers Cathode strip drift chambers................  e+e+ e-e- Preradiator – convert & measure  properties 64 Layers (4% X 0 /layer, 2.7 X 0 ) 256 Chambers 288 Scintillator Plates (1200 m 2) 150,000 Channels Readout 4m

28. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting28 Preradiator Angular resolution: 25 mr at 250 MeV/c Simulations agree with measurements. KOPIO Prototype Measurements – BNL LEGS Tagged Photon Beams

29. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting29 Shashlyk Photon Calorimeter APD Shashlyk modules prototyped and tested in beams. Required specs have all been met

30. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting30 Beam test of Calorimeter modules Simulation: Combined PR +CAL Energy Resolution

31. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting31 Charged Particle Veto in vacuum

32. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting32 Plastic Scintillator – backed up by  vetoes! 185 290 10 -5 10 -4 10 -3 Data MC Charged Particle Veto Performance 10 -6

33. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting33 Every detector is a photon veto! US Wall Barrel veto Preradiator Prerad outer veto Calorimeter  vetoes in D4 sweeping magnet  vetoes in DS vacuum pipe Fine-sampling lead/scintillator-based shower counters of shashlyk & bar geometry. All thick enough so punch- through not an issue. All with sufficient efficiency

34. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting34 E949 Single  Ineff’y Measurement ++ 22 11 K  2 Decay

35. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting35 KOPIO PV Estimates and Simulations based on improved BNL E949 Measurements supplemented by FLUKA calculations 1 MeV Visible Energy Threshold Photon Veto Inefficiency

36. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting36 Catcher: Hadron Blind Beam  Veto Aerogel Counter beam 420 modules of Pb-Aerogel counter

37. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting37 Catcher R&D results Modules prototyped and tested in beams.

38. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting38 K L modes simulated for bkgnd studies Largest back- grounds

39. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting39 Other Backgrounds K + contamination of beam: <0.001 of signal rate K L  K + e -, K - e + : ~ 0.001 of signal rate nN   N: negligible production from residual gas in decay volume if pressure<10 -6 Torr. Requirements on reconstructed Z V (K L ) suppress rate from US wall to <0.01 of signal rate n: far smaller than neutron background Hyperons: <10 -5 of signal rate Fake photons < 0.05 of signal rate assuming ~10 -3  10 -3 suppression from (vetoing)  (  /n discrimination) Two K L giving single candidate: negligible due to vetoes (K L   X)  (     e  ): ~0.01 of signal rate K S      10 -4 of K L     background rate _

40. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting40 Kinematic Separation of Signal &Backgrounds SignalBackgrounds Pion kinetic energy squared (T *2 ) vs Ln(Missing Energy)

41. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting41

42. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting42 KTeV (FNAL): B(K L  0 ) < 5.9  10 -7 (90% CL) KEK E391a >10 -9 ??  J-PARC LOI KOPIO (BNL): single event sensitivity <10 -12 –Discovery (5  ) for B(K L  0 )>5  10 -11 or <1.8  10 -11 –If nothing new, ~300 SM events Rule out BRs outside of (1  0.17)BR SM @ 95%CL Bound operators, B-system can’t access _ _

43. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting43 KOPIO Parameters  bunch width (extinction)200ps (10 -3 ) Beam halo10 -4 Vacuum10 -7 Torr   resolution @ 250MeV25 mr E  resolution2.7%/  E  (GeV) t  resolution90ps/  E  (GeV)  veto inefficiency(outside beam)E949 or better  veto efficiency(inside beam)>99% at 300 MeV n efficiency (inside beam)<0.3% at 800 MeV Charged particle inefficiency2  10 -5 (  + ), 1.2  10 -4 (  - )

44. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting44 Preradiator 64 Layers (4% X 0 /layer, 2.7 X 0 ) 256 Chambers 288 Scintillator Plates (1200 m 2) 150,000 Channels Readout 4m

45. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting45 Primary detection mode: Secondary mode: 2 photons covert in preradiator 1 photon in preradiator, 1 in BV Reconstruct 1 st  e + e - in “Preradiator”, Point to K decay vertex in vacuum

46. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting46 Simulation: Combined PR + CAL Energy Resolution Shashlyk Beam Measurements

47. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting47 Barrel Veto/Calorimeter Cylindrical array of 840 modules with 2.5m ID Both signal detection and vetoing functions –1  in prerad + 1  in BV/C Modified version of calorimeter shashlyk technology, pmt readout –Energy resolution calculated to be almost as good as calorimeter –Time resolution should be comparable B V/C lined with thin, high-efficiency, charged particle veto scintillators US end of barrel sealed by wall of plate shower-counter vetoes

48. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting48 D4 & downstream vetoes Charged &  vetoes in D4 sweeping magnet –Field sweeps vertically DS vetoes detect  ’s emerging from the beam Lead/scintillator plate sandwich counters Hermeticity completed by catcher veto at the back

49. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting49 Primary Backgrounds K * PV 2 K * C 2 * PV K * C 2 K * PV 4 Rejections Worst backgrounds are from K L decay

50. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting50 Simulation Tools GEANT3 –FLUKA, GCALOR, GHEISHA hadronic packages GEANT4 FLUKA MCNPX MARS KOPTICs –custom optics simulator FastMC –uses input from detailed simulators + input from experiments Critical parameters directly measured –Either in prototype tests or experiments

51. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting51 Alternative Display of Results

52. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting52 KOPIO Operations Plan 2010 Test Run – partial detector 2011 Engineering Run “Discovery phase”: Sensitivity goal:~10 -10 2012-16 Data Acquisition

53. June 20, 2005David E. Jaffe 2005 RHIC & AGS Users’ meeting53 Branching Ratio Measurement Precision Precision at B(K L  0  ) = 3  10 -11 Using probability likelihood method employing all observed events (approximately 300)  10% (Statistical) Precision on Im t :  5%