NA48/2 KABES detector: a short overview

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NA48/2 KABES detector a short overview
Massimiliano Fiorini (Università degli Studi di
Ferrara)
On behalf of M. Boyer, C. Cheshkov, J.B. Cheze,
X. Coppolani, A. Delbart, J. Derré, S. Herlant,
P. Le-Bourlout, P. Legou, O. Maillard, I.
Mandjavidze, C. Mazur, E. Mazzucato, F. Nizery,
F. Orsini, B. Peyaud, M. Riallot, B. Vallage. CEA
DSM/Dapnia Saclay S. Basilev, Y. Potrebenikov,
I. Slepnev, V. Slepnev. JINR/Dubna
K RARE DECAY WORKSHOP - Frascati - 27 May 2005
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NA48 KABES principle TPC micromegas
TOTAL X/X0 1.3x10-3
Operated _at_ Edrift 0.83 kV/cm vDRIFT 8
cm/µs Tdrift1 Tdrift2 750 ns 48 strips with
0.8 mm pitch Very low discharge probability
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KABES main features
Reference B. Peyaud et al. NIM A 535 (2004)
247-252
Gas mixture Ne(79)C2H6(11)CF4(10)
Time window (extraction)
0.5 ?s Number of TDC channels 6x48288
Central strips rate 2 MHz Limits of TDC
readout Maximum particle flux 40
Mp/s Maximum hit rate /strip 8
Mhit/s
TOT Ttrailing-Tleading ltTOTgt 35 ns Low
occupancy _at_20 MHz ltStrip multiplicitygt 1.5
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Performance in NA48/2
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TEST of 25 µm mesh detector FADC readout

• 8 bit FADC 960 MHz (2 interleaved 480 MHz)
  only 18 channels at 480 MHz sampling frequency
• new mesh gap ltpulse widthgt reduced to
  20 ns
• beam momentum 75 GeV/c (only K)
• beam intensity scan up to 16x nominal intensity
• better double pulse
• resolution with FADC
• extract time
• information from fit
• reconstruction of
• tracks even in high
• rate beam

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Conclusions

• high rate and high-resolution TPC operating with
  50 µm micromegas amplification gap _at_20 MHz
• further improvement of occupancy with 25 µm
  amplification gap is expected
• all mesh currents are linear at high beam rate
  (up to 16xI0) KABES does NOT saturate
• LATEST RESULT use of a faster preamplifier
  reduces the pulse width of a factor of 2
• Further Investigations different gas mixture,
  use of double amplification gap