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Future of Rare Kaon Decays at the CERN-SPS

Future of Rare Kaon Decays at the CERN-SPS. Fermilab, October 7 , 2004 Ceccucci for the NA48-Future Working Group. “CERN Director General Outlines Seven-point Strategy for European Laboratory”.

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Future of Rare Kaon Decays at the CERN-SPS

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  1. Future of Rare Kaon Decays at the CERN-SPS • Fermilab, October 7 , 2004 • Ceccucci for the • NA48-Future Working Group A. Ceccucci/ CERN

  2. “CERN Director General Outlines Seven-point Strategy for European Laboratory” 18.6.2004 Official CERN Press ReleaseGeneva 18 June 2004. At the 128th session of CERN Council, held today under the chairmanship of Professor Enzo Iarocci, CERN Director General, Robert Aymar, outlined a seven-point scientific strategy for the Organization. Top of the list was completion of the Large Hadron Collider (LHC) project with start-up on schedule in 2007. This was followed by consolidation of existing infrastructure at CERN to guarantee reliable operation of the LHC, with the third priority being an examination of a possible future experimental programme apart from the LHC.……… ………. A. Ceccucci/ CERN

  3. NA48 Data Taking NA48: ’/ 1997 ’/ 1998 ’/ 1999 no spectrometer 2000 KL NA48/1 KS ’/lower inst. intensity 2001 2002 NA48/1: KS 2003 NA48/2: K Total: 5.3M KL00 1996 Re e’/e = 14.7 ± 2.2 10-4 Ave: Re e’/e = 16.7 ± 2.3 10-4 + KLRare Decays First observation of K0S→p0 e+e-and K0S→p0m+m- Search for Direct CP-Violation in charged kaon decays NA48/2: K 2004 A. Ceccucci/ CERN

  4. NA48-Future Working Group CERN-SPSC-2004-010 SPSC-EOI-002 • We identified the Rare Kaon Decays as the next logical step of the Kaon Programme at CERN • Short term (2004-2010): NA48/3K+→p+n n **LETTER OF INTENT** • Longer term (>2010): • Assuming a new or refurbished SPS capable to deliver higher intensity/energy as the ultimate injector for LHC NA48/4KL→p0 ee (mm) NA48/5KL→p0n n A. Ceccucci/ CERN

  5. Letter of Intent to Measure the Rare Decay K+→ p+ n n at the CERN SPS Cambridge: D. Munday; CERN: N. Cabibbo, A. Ceccucci*, V. Falaleev, F. Formenti, B. Hallgren, A. Gonidec, P. Jarron, M. Losasso, A. Norton, P. Riedler G. Stefanini; Dubna: S. Balev, S. Bazylev, P. Frabetti, E. Goudzovski, D. Gurev,V. Kekelidze, D. Madigozhin, N. Molokanova, R. Pismennyy, Y. Potrebenikov, A. Zinchenko; Ferrara: W. Baldini, A. Cotta Ramusino, P. Dalpiaz, C. Damiani, M. Fiorini, A. Gianoli, M. Martini, F. Petrucci, M. Savrie’, M. Scarpa, H. Wahl; Firenze: E. Iacopini, M. Lenti, G. Ruggiero; Mainz: K. Kleinknecht, B. Renk, R. Wanke; UC Merced: R. Winston; Perugia: P. Cenci, M. Piccini; Pisa: A. Bigi, R. Casali, G. Collazuol, F. Costantini, L. Di Lella, N.Doble, R. Fantechi, S.Giudici, I. Mannelli, A. Michetti, G.M. Pierazzini, M. Sozzi; Saclay: B. Peyaud, J. Derre; Sofia: V. Kozhuharov, L.Litov, S. Stoynev; Torino: C. Biino, F. Marchetto *contact person A. Ceccucci/ CERN

  6. Main K+decay modes competing with K+→p+nn BR(K+→p+nn)~10-10 !! A. Ceccucci/ CERN

  7. Framework • So far K+→p+nn only studied with kaon decays at rest • This limits the statistics to a few events • We plan to collect ~100 events at the SPS by 2010 • We dubbed this initiative NA48/3 • the name is not an issue at this early stage • Employ high energy kaons has the following advantages: • The larger cross section increases the kaon content in the beam • The rejection of backgrounds from K+→p+p0is simplified • Tens of GeV of EM energy is deposited in the photon vetoes! • Accidental background are minimised • The use of unseparated beam becomes a possibility • 2/3 of the final state is invisible !! • The kaon and the pion must be redundantly measured to keep backgrounds under control • Muon and photon vetoes are essential A. Ceccucci/ CERN

  8. Region I Region II Kinematics A. Ceccucci/ CERN

  9. Acceptance Region I Region II Acceptance Acceptance 75 GeV/c A. Ceccucci/ CERN

  10. THE BEAM A. Ceccucci/ CERN

  11. Rationale p0= primary proton momentum pk= secondary beam momentum • Kaon production increases as p02 • Use highest p0 (that is 400 GeV/c protons from SPS) • For a fixed fiducial length the number of decays increases as pk. If p0 is fixed the maximum is for: pk = 0.23 p0 • For unseparated beams the limitation comes from the detectors, not from the amount of protons A. Ceccucci/ CERN

  12. Choice of pk=75 GeV/c 75 GeV/c is about the maximum momentum for which a beam incorporating stages for large solid angle acceptance, momentum selection, K+ tagging, beam momentum measurement and tracking using standard beam elements can fit into the present length of 102 m A. Ceccucci/ CERN

  13. NA48/3: Beam Layout Dipoles Dipoles Beam-line 102 m long about 17% K+ lost A. Ceccucci/ CERN

  14. NA48/3: Beam Across Tank A. Ceccucci/ CERN

  15. Already Available New high-intensity K+ beam for NA48/3 A. Ceccucci/ CERN

  16. 1HISTOGRAM NO 21 DISTRIBUTION OF P IN GEVC 102.000 M FROM THE TARGET0 INTERVAL SCALE FACTOR.. 100 X'S EQUAL 5637 ENTRIES0LESS THAN 72.000 0 72.000 TO 72.200 0 72.200 TO 72.400 0 72.400 TO 72.600 0 72.600 TO 72.800 0 72.800 TO 73.000 1 73.000 TO 73.200 20 73.200 TO 73.400 178 XXX 73.400 TO 73.600 576 XXXXXXXXXX 73.600 TO 73.800 1210 XXXXXXXXXXXXXXXXXXXXX 73.800 TO 74.000 2068 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 74.000 TO 74.200 2870 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 74.200 TO 74.400 3727 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 74.400 TO 74.600 4598 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 74.600 TO 74.800 5354 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 74.800 TO 75.000 5637 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 75.000 TO 75.200 5596 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 75.200 TO 75.400 5126 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 75.400 TO 75.600 4288 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 75.600 TO 75.800 3400 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 75.800 TO 76.000 2623 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 76.000 TO 76.200 1820 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 76.200 TO 76.400 1068 XXXXXXXXXXXXXXXXXX 76.400 TO 76.600 552 XXXXXXXXX 76.600 TO 76.800 250 XXXX 76.800 TO 77.000 61 X 77.000 TO 77.200 8 77.200 TO 77.400 0 77.400 TO 77.600 0 77.600 TO 77.800 0 77.800 TO 78.000 00GREATER THAN 78.000 00 TOTAL NUMBER OF ENTRIES = 51031 INCLUDING OVERFLOW AND UNDERFLOW0 MEAN = 74.981 RMS HALF WIDTH = 0.7100HISTOGRAM NO 21 DISTRIBUTION OF P IN GEVC 102.000 M FROM THE TARGET TURTLE SIMULATION MOMENTUM DISTRIBUTION <p> = 74.981 GeV/c, RMS = 0.710 GeV/c A. Ceccucci/ CERN

  17. Y [mm] X [mm] -60.000 -20.000 20.000 60.000 TOTALS I**---**---**---**---**---**---**I---------60.000 I I 0-54.000 I I 0-48.000 I I 0-42.000 I I 0-36.000 I I 0-30.000 I I 0-24.000 I 8T$$$$$$$$$A I 932-18.000 I A$$$$$$$$$$$$A I 5407-12.000 I Z$$$$$$$$$$$$Z I 8326 -6.000 I $$$$$$$$$$$$$$ I 9999 0.000 I $$$$$$$$$$$$$$ I 9999 6.000 I W$$$$$$$$$$$$W I 8536 12.000 I 4$$$$$$$$$$$$G I 5529 18.000 I 3Q$$$$$$$$T2 I 787 24.000 I I 0 30.000 I I 0 36.000 I I 0 42.000 I I 0 48.000 I I 0 54.000 I I 0 I**---**---**---**---**---**---**I-------- I I I 134455554431 I I 15428485392461 I I 59077738177357 I TOTALS I 000000007855957371007700000000 I 9999 TOTAL NUMBER OF ENTRIES = 51031 -60.000 -20.000 20.000 60.000 TOTALS I**---**---**---**---**---**---**I---------60.000 I I 0-54.000 I I 0-48.000 I I 0-42.000 I I 0-36.000 I I 0-30.000 I I 0-24.000 I 2AQ$$$$$$OF1 I 397-18.000 I $$$$$$$$$$$$ I 4016-12.000 I 1$$$$$$$$$$$$4 I 8053 -6.000 I 2$$$$$$$$$$$$2 I 9999 0.000 I 3$$$$$$$$$$$$2 I 9999 6.000 I $$$$$$$$$$$$ I 8186 12.000 I $$$$$$$$$$$$2 I 4102 18.000 I 2GS$$$$$$$F2 I 396 24.000 I I 0 30.000 I I 0 36.000 I I 0 42.000 I I 0 48.000 I I 0 54.000 I I 0 I**---**---**---**---**---**---**I-------- I I I 2456666542 I I 631337614046 I I 7435062357861 I TOTALS I 000000006682187334832000000000 I 9999 TOTAL NUMBER OF ENTRIES = 51031 BEAM TRANSVERE SIZE SPIBES2 -60.000 -20.000 20.000 60.000 TOTALS I**---**---**---**---**---**---**I---------60.000 I I 0-54.000 I I 0-48.000 I I 0-42.000 I I 0-36.000 I I 0-30.000 I I 0 -24.000 I 4H$$$$$$$$K5 I 603-18.000 I 3$$$$$$$$$$$$ I 5010-12.000 I H$$$$$$$$$$$$K I 8414 -6.000 I H$$$$$$$$$$$$H I 9999 0.000 I L$$$$$$$$$$$$H I 9999 6.000 I A$$$$$$$$$$$$E I 8483 12.000 I $$$$$$$$$$$$6 I 5058 18.000 I 4L$$$$$$$$H3 I 590 24.000 I I 0 30.000 I I 0 36.000 I I 0 42.000 I I 0 48.000 I I 0 54.000 I I 0 I**---**---**---**---**---**---**I-------- I I I 134456555431 I I 213971951312 I I 61257420138277 I TOTALS I 000000008999158636733400000000 I 9999 TOTAL NUMBER OF ENTRIES = 51031 SPIBES1 FTPC (KABES) A. Ceccucci/ CERN

  18. Y [mm] X [mm] Spot at Wire Chamber 6: 1HISTOGRAM NO 29 HORIZONTAL AXIS X IN MM 204.858 M FROM THE TARGET VERTICAL AXIS Y IN MM 204.858 M FROM THE TARGET0 -60.000 -20.000 20.000 60.000+ TOTALS I**---**---**---**---**---**---**I-------- -60.000 TO -54.000 I I 0 -54.000 TO -48.000 I I 0 -48.000 TO -42.000 I I 0 -42.000 TO -36.000 I I 0 -36.000 TO -30.000 I 2321 11 I 10 -30.000 TO -24.000 I 159XT$$$$SJE73 I 334-24.000 TO -18.000 I 8$$$$$$$$$$$U72 I 1947 -18.000 TO -12.000 I 1E$$$$$$$$$$$$D I 4900 -12.000 TO -6.000 I G$$$$$$$$$$$$J1 I 8143 -6.000 TO 0.000 I 1L$$$$$$$$$$$$I2 I 9999 0.000 TO 6.000 I G$$$$$$$$$$$$82 I 9984 6.000 TO 12.000 I G$$$$$$$$$$$$E1 I 8252 12.000 TO 18.000 I F$$$$$$$$$$$$E1 I 4901 18.000 TO 24.000 I AV$$$$$$$$$$X7 I 1929 24.000 TO 30.000 I 2ERYVWQSPFF5 I 254 30.000 TO 36.000 I 21 1 1 I 5 36.000 TO 42.000 I I 0 42.000 TO 48.000 I I 0 48.000 TO 54.000 I I 0 54.000 TO 60.000 I I 0 I**---**---**---**---**---**---**I-------- I I I 1356776531 I I 15731887723651 I I 16166042762880 I TOTALS I 000000027056033304565390000000 I 9999 0 TOTAL NUMBER OF ENTRIES = 51031 INCLUDING UNDERFLOW AND OVERFLOW AS FOLLOWS 0 UNDERFLOW OVERFLOW ACROSS 0 0 DOWN 0 00HISTOGRAM NO 29 HORIZONTAL AXIS X IN MM 204.858 M FROM THE TARGET VERTICAL AXIS Y IN MM 204.858 M FROM THE TARGET A. Ceccucci/ CERN

  19. Muon Halo Calculation • The flux of “halo muons” crossing the WC has been calculated using the HALO program: • Single rate in the WC is dominated by muons from kaon decays • The total halo is about 7 MHz • Thank to the new beam design, the situation appears much better than in NA48/2 A. Ceccucci/ CERN

  20. DETECTORS A. Ceccucci/ CERN

  21. NA48/3 Detector Layout 10 MHz Kaon decays 800 MHz (p/K/p) Only the upstream detectors see the 800 MHz beam A. Ceccucci/ CERN

  22. Detectors • CEDAR • To tag positive kaon identification • GIGATRACKER • To Track secondary beam before it enters the decay region • ANTI • Photon vetoes surrounding the decay tank • WC • Wire chambers to track the kaon decay products • CHOD • Fast hodoscope to make a tight K-pi time coincidence • LKR • Forward photon veto and e.m. calorimeter • MAMUD • Hadron calorimeter, muon veto and sweeping magnet • SAC and CHV • Small angle photon and charged particle vetoes A. Ceccucci/ CERN

  23. 2004 Test beam • It was of the utmost importance to test in 2004 the performance of the NA48 detectors at intensities comparable to NA48/3 (no SPS in 2005!) • This was a unique opportunity to collect data to validate our –simulated- understanding to quantify the necessary effort (technical and financial) to transform NA48 into an experiment capable to address K+→p+nn. • Thank to the extension granted by CERN we could test: • WC: raise intensity to about 30 times NA48/2 • GIGATRACKER • Tested a state-of the-art ALICE SPD assembly in our beam • Use a thinner 25 micron MICROMEGAS amplification gap • Read out KABES with 480 MHz FADC (former NA48 tagger FADC) • Read KABES at ~14 times the NA48/2 rate • LKR: Complement the photon coverage with extra LKr electronics and a Small Angle Calorimeter SAC (CMS RCAL prototype) • CHOD test of prototypes • A few very preliminary results will be shown A. Ceccucci/ CERN

  24. Increase of beam Intensity • I0 = Intensity of NA48/2 K+ beam • Tune the K12 beam to + 75 GeV/c • Open up the aperture of the P42 line (X3.5) • Opening momentum bite DP/P from 5 to 20 % (X4) • Turn on both K+ and K- polarities (X1.3) • Employ a shorter T4 target (100 mm instead of 300 mm) (X1.6) • Tot ~  29 I0 • Accidentals in  29 I0 beam NA48/2 are dominated by pions rather than kaons • Expect cleaner situation with new beam A. Ceccucci/ CERN

  25. CEDAR • CErenkov Differential Counter with Achromatic Ring Focus • He pressure adjusted to make it sensitive only to kaons • Requires beam divergency < 0.1 mrad • Built at CERN in the 80’s (Bovet et al.) for use in the SPS beam lines • We will certainly need to upgrade the photon detectors and front-end electronicsto operate at the NA48/3 rates (~60 MHz) Beam A. Ceccucci/ CERN

  26. K/p Cedar-W Cedar-N CEDAR A. Ceccucci/ CERN

  27. GIGATRACKER • Specifications: • Momentum resolution to ~ 0.5 % • Angular resolution ~ 10 mrad • Time resolution ~ 100 ps • Minimal material budget • Perform all of the above in • 800 MHz hadron beam, 40 MHz / cm^2 • Hybrid Detector: • SPIBES (Fast Si micro-pixels) • Momentum measurement • Facilitate pattern recognition in subsequent FTPC • Time coincidence with CHOD • FTPC (NA48/2 KABES technology with FADC r/o) • Track direction A. Ceccucci/ CERN

  28. SPIBES1 SPIBES2 FTPC 6.25 12.45 m GIGATRACKER • momentum: use SP1 and SP2 to measure y = 40 mm displacement. Assuming σp~50µm from pixel and 350µm thick Si (0.37% X0) • σ= (σp√2 ‡ σMS ) ⁄ 40 mm = 0.25% • direction: use SP2 and FTPC. Assuming σp~100µm from pixel and similar from FTPC and no MS from FTPC (from SP2 no influence) • ∆Өх= σp√2 ⁄ 12.4m = 11µrad Tails in the beam? (Turtle simulation) • time resolution: essential to obtain a low background due to accidental hits and to allow the pattern recognition (see result from test beam) . For a pixel C≈ 100 fF a risetime ~ 2 ns should be achievable for 130 nm technology and a good S/N. A. Ceccucci/ CERN Mara Martini

  29. 5 cm Proposal for SPIBES Beam square shape 5x5 cm2 • An effort must be done to minimize the overall thickness to ≤ 350 µm of Si without loosing in yield . • Should avoid a substrate • The cooling should be studied • The dimension of the pixel cell and of the chip must be optimized to fit the 2n rule and to match the design requirements (PA, Discri, multiplexed TDC, power consumption, r/o bus) 300 x 100 µm pixel cell 80000 pixels in total to cover the beam A. Ceccucci/ CERN Mara Martini

  30. Test of ALICE pixel in NA48/2 beam 1 ALICE assembly 1 DAQ adapter card 30 m DAQ cables 30 m JTAG control cables LV and HV power supplies VME crate with r.o. module (Pilot) and JTAG controller JTAG multiplexer MXI interface to PC ALICE PTS software (LabView) PC remotely controlled from NA48 control room A. Ceccucci/ CERN

  31. Single Chip Alice Assembly tested • Assembly 7: • 150µm thick ALICE chip • 200µm thick sensor • 1.1 % X0 all together • Mounted on a thin test-PCB • Vfd=15V • Vop=50V • 8192 pixels • Produced 2003, tested in • ALICE p-TB 2003 Sensor Chip A. Ceccucci/ CERN

  32. MULTIPLICITY (200 nsec gate) I0 I0/4 <mult> = 1.1 <mult> = 1.3 14xI0 4xI0 <mult> = 7.8 <mult> = 3.1 A. Ceccucci/ CERN

  33. MULTIPLICITY (200 nsec gate) MULTIPLICITY (200 nsec gate) for r/o window of 10 ns: 1GHz x 10 ns x 1.1 ~ 10 hits/ trig for σ = 100ps we expect in a ±2.5σ: 0.5 accident hits/trig A. Ceccucci/ CERN

  34. FTPC (KABES+FADC) • NA48/2 • KABES has achieved very good performance • Position resolution ~ 70 micron • Time resolution ~ 0.6 ns • Rate per micro-strip ~ 2 MHz • NA48/3 • Intensity ~ 10 higher per unit area • 600 ns drift • The long drift (600 ns) makes a standalone pattern recognition very difficult or just impossible ( That’s why we plan to have SPIBES in front) • To reduce double pulse resolution and improve the time resolution one has to reduce the pulse duration and possibly read-out every micro-strip with 1 GHz FADC A. Ceccucci/ CERN

  35. Tdrift2 Micromegas Gap 50 μm Micromegas Gap 50 μm Tdrift1 KABES principle: TPC + micromegas Operated @ Edrift=0.83kV/cm Tdrift1 + Tdrift2 = 750ns 48 strips with 0.8 mm pitch Very low discharge probability A. Ceccucci/ CERN

  36. TEST OF KABES IN 2004LOW INTENSITY A. Ceccucci/ CERN

  37. KABES 25 micron amplification gap Recent lab test with 25 mm gap Width ~30 ns Width ~18 ns 50 mm gap 25 mm gap improvement of occupancy observed with25mmamplification gap A. Ceccucci/ CERN

  38. BEAM DATA: 50/25μ mesh 2003/2004Time over Threshold (ns) A. Ceccucci/ CERN

  39. 2004 KABES TEST HIGH INTENSITY FLUX PER UNIT AREA CLOSE TO NA48/3 ! A. Ceccucci/ CERN

  40. TEST OF KABES with 480 MHz FADC A. Ceccucci/ CERN

  41. FADC Readout (1) • 8 bit FADC 960 MHz (2 interleaved 480 MHz) from NA48 proton tagger • 9 FADC boards (18 channels “480 MHz mode”) • 18 FADC channels connected to KABES strips in station upstream UP and downstream K5 23  FADC 1 K5 24  FADC 8 K5 25  FADC 3 K5 26  FADC 5 K5 27  FADC 7 K1 23  FADC 16 K1 24  FADC 14 K1 25  FADC 12 K1 26  FADC 10 K2 K1 K6 23  FADC 9 K6 24  FADC 11 K6 25  FADC 13 K6 26  FADC 15 K6 27  FADC 17 K2 23  FADC 6 K2 24  FADC 4 K2 25  FADC 2 K2 26  FADC 18 K5 K6 K3 K4 A. Ceccucci/ CERN

  42. Multiple pulses without Zero-suppression A. Ceccucci/ CERN

  43. FADC data (1) • Distribution of time over threshold • Low intensity run • Threshold set to 37 ADC counts (~27 mV) • ±2 samples over threshold ~20 ns time over threshold (KABES 25 µm mesh) A. Ceccucci/ CERN

  44. FADC data • Number of pulses per channel as a function of beam intensity • noisy channels 10,12,14,16 all connected to K1 x1 x3 x7 x12 A. Ceccucci/ CERN

  45. Multiple pulses with Zero-supp • Some data from RUN 16964 (14xI0) • horizontal scale: FADC time units (2×1.04 ns) A. Ceccucci/ CERN

  46. Attempt to fit single pulses • fit of 500 FADC pulses from the low intensity RUN (16916) • 4 parameters function used: • uncertainty of 1.7 counts per FADC value A. Ceccucci/ CERN

  47. Attempt to fit multiple pulses • “hand fit” of a six pulses event from run 16964 (x 14 I0) A. Ceccucci/ CERN

  48. KABES FADC Conclusion • We read-out the micro-strips with FADC • Double pulse resolution capability is very good • To do list: • develop reconstruction from list of times in strips and measure resolution (space, time, angular) as a function of beam intensity A. Ceccucci/ CERN

  49. ANTI • Set of ring-shaped photon vetoes surrounding the decay tank • Specification: inefficiency to detect photons above 100 MeV < 10-4 • The NA48 ANTI’s (AKL) need to be replaced • Extensive R&D Performed by American and Japanese groups • Claims that inefficiency as low as 10-5 can be achieved • Baseline solution: Lead/ Plastic scintillator sandwich (1-2 mm lead / 5 mm plastic scintillator) • Cost driver of NA48/3 A. Ceccucci/ CERN

  50. Current NA48 ANTI A. Ceccucci/ CERN

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