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DCH Summary

DCH Summary. G. Finocchiaro For the DCH group XIV SuperB Meeting LNF, 1 October 2010. Topics Discussed in This Meeting. Lab activities Background studies Cell design optimization DCH Readout architecture. LAB activities @LNF – Prototype 1.

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DCH Summary

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  1. DCH Summary G. Finocchiaro For the DCH group XIV SuperB Meeting LNF, 1 October 2010

  2. Topics Discussed in This Meeting • Lab activities • Background studies • Cell design optimization • DCH Readout architecture G. Finocchiaro

  3. LAB activities @LNF – Prototype 1 Continuing cosmic ray data taking with “Proto 1” • 6x4 BABAR–like hex cells – external tracker with ≤80mm extrapolation accuracy • Campaign with He + various iC4H10/CH4/C2H6 mixtures and HV / threshold settings MT track PROTO1 track Al-Mylar windows 10cm lead pcut~150MeV/c G. Finocchiaro

  4. Space-time correlations Example: 60%He-40%C2H6 @HV=2010V • Measured time vs. extrapolated impact parameter – t vs. R • Fit R vs. t relationship using Chebyshev polynomials of order (up to) 5 • Time range rescaled to [-1,+1] interval Drift velocity G. Finocchiaro

  5. Space-time relations fits (cont.) • Border cells show some L-R asymmetry • Internal cells are symmetric L+R RIGTH L+R RIGTH LEFT LEFT 60%He-40%C2H6 HV=2010V G. Finocchiaro

  6. Track fit residuals & Spatial resolution – 60%He-40%C2H6 60%He-40%C2H6 HV=2010V G. Finocchiaro

  7. Gas Mixture Comparison PRESENTED @ ELBA NEW • tmax and space resolution depend on other parameters. Figures shown are preliminary and indicative • Results for iC4H10 and CH4 –based gas mixtures to be updated with analysis software used for C2H6 gases G. Finocchiaro

  8. Drift Tubes for Cluster Counting CINJ = 1.8 pF • Two square-section tubes (24mm side) built to study cluster counting issues in simplified environment. • One tube (400mm long), equipped with 250MHz BW preamplifier placed on top of our telescope Gain ≈ 5 mV/fC Noise ≈ 1900 erms @ CIN = 3pF • Waveform digitized with the DRS4 switched capacitor array (http://drs.web.psi.ch/) • 4 channels, 1024 channels each @ 5GSa/sec max. • remaining channels read 3 cells of Proto 1 • Dump waveforms when at least one of them exceeds 25mV In spite of x3 higher preamp bandwidth, a noise level similar to proto1 (~1.4 mV RMS) is obtained with a careful shielding (…) G. Finocchiaro

  9. Counting Clusters… • Adequate preamp bandwidth is (clearly) crucial to count clusters (1st attempt at) Peak finding 85%He-15%C2H6 nP=10.2/cm INPUT SIGNAL 1024 channels, 2Gsample/sec TARGET SIGNAL (cluster) Position of peaks from finding algorithm G. Finocchiaro

  10. Lab Activity @TRIUMF: Wire Aging Tests size of single electron peak increases due to Malter effect as chamber ages • Goal is to verify that the chamber will survive the SuperB lifetime. • Test proposed materials using single cell, as per Boyarski. e.g. bare Al wire. • Primarily a test of Malter effect (field wire aging). • Uses 55Fe both to age the wires and to characterize performance. A. M. Boyarski, Nucl. Instr. Meth. A 535, 632 (2004) SCHEMATIC picoammeter monitors total deposited charge G. Finocchiaro

  11. Charge collected by aging chamber in 55Fe events low pulse-height events due to interactions near edge of cell Higher gain (3.3x) — 55Fe peak off scale to precisely measure the 1e- peak auger events in gold normalized noise/cosmic spectrum 55Fe G. Finocchiaro ADC channel

  12. Lab Activity @TRIUMF: Cluster Counting • Single-cell 2.7m long drift tube to test the feasibility of detecting individual clusters as they drift to the sense wire. • dispersion and attenuation as a function of distance from preamp. • Start with 55Fe, ~170 e- in BaBar gas (He:Iso 80:20, no water). • aim to use UV laser eventually, to generate small, triggered pulses • First preliminary results • example: rise time as a function of distance from preamp aluminized-mylar windows G. Finocchiaro

  13. Topics Discussed in This Meeting • Lab activities • Background studies • Cell design optimization • DCH Readout architecture G. Finocchiaro

  14. “SuperB” layer configuration in FullSim G. Finocchiaro

  15. Occupancies vs. energies Dana Lindemann (McGill) G. Finocchiaro

  16. Shield Geometry G. Finocchiaro

  17. G. Finocchiaro

  18. Occupancy from Large-angle Bhabha’s with FastSim D. Swersky (McGill) SHIELDED UNSHIELDED G. Finocchiaro

  19. Issues to be solved • Background rate depends on GEANT4 step length • incorrect treatment of Coulomb diffusion in low-density material? • Belle-II estimate much smaller background rate from radiative Bhabha’s and much larger from Touschek than we do (H. Nakayama’ talk on Tuesday 28th) G. Finocchiaro

  20. Topics Discussed in This Meeting • Lab activities • Background studies • Cell layout optimization with Garfield • DCH Readout architecture G. Finocchiaro

  21. Garfield studies of cell shapeand superlayer transitions Chris Hearty, Philip Lu

  22. Transitions between stereo superlayers

  23. Stereo-stereo transition: Impact on Reconstruction

  24. Axial-stereo transition G. Finocchiaro

  25. Axial-stereotransition:impactonreconstruction G. Finocchiaro

  26. Topics Discussed in This Meeting • Lab activities • Background studies • Cell design optimization • DCH Readout architecture G. Finocchiaro

  27. G. FELICI (LNF) Data transfer optimization Trigger 1 Ch n 32 samples Trigger 2 Ch n+i 32 samples Trigger 3 Ch n+i 32 samples • FEE data transfer optimization : download the 3 events as a single “big” event • Pro : Front-End data transfer optimization • Cons : • events are overlapped in the same data frame (further elaboration required to split single events) • data frames do not have the same lengths (L1 trigger occurrences) The trigger burst case Event management optimization Trigger 1 Ch n 32 samples Trigger 2 Ch n+i 32 samples Trigger 3 Ch n+i 32 samples • Single event data transfer : readout each event separately • Pro : • Front-End events have the same size • FEX can be applied while reading the event • Readout procedure provides event de-randomization • Cons : • Partial (previous) L1 event re-reading LNF-SuperB Workshop – September 2010

  28. Trigger Latency Time + n samples (Dual-port memory) 32 word block data readout RO buffer n 2 1 0 Ev3 Ev2 Ev1 DATA RO SM (FEX) Pushing mode Concentrator board Sampled data A pushing-mode FE readout architecture (counter value @ L1) - Latency Read ADDR ADDR Sampling clock COUNTER (0 – n) ADDR FiFO Empty L1 FIFO FiFO Read L1 (synchronized by sampling clock) Data (counter value @ L1) NB : minimum trigger spacing > sampling period (≈ 36 ns) A simulation of the readout architecture will be carried out in the next weeks LNF-SuperB Workshop – September 2010

  29. Summary • Good progress in many areas including: • study of gas mixtures with prototypes • evaluation of background for different shields and DCH geometries • Definition of optimal cell layout • Aging tests • Effort starting on: • Cluster counting R&D • Design of readout chain • DCH trigger still to be tackled G. Finocchiaro

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