Update on the RICH Beamtest

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Update on the RICH Beamtest
Jianchun Wang 03/11/05 BTeV Collaboration meeting
The RICH Group M. Artuso, S. Blusk, C.
Boulahouache, J. Butt, O. Dorjkhaidav, A. Kanan,
N. Menaa, R. Mountain, H. Muramatsu, R.
Nandakumar, K. Randrianarivony, L. Redjimi, R.
Sia, T.Skwarnicki, S. Stone, J.C. Wang, H.
Zhang Syracuse University H. Cease Fermilab
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Phase II Beamtest(01/10/05-01/31/05)

• The DAQ system is more sophisticated than that of
  phase I. It is able to readout all MAPMTs for
  each event.
• New firmware has been developed that allows
  individual track trigger using coincident signal
  of finger counters.
• The bias setting of front end electronics has
  been optimized.
• We developed new baseboard that provides a better
  match to the dynamic range of the front end
  electronics without sacrificing collection
  efficiency.

Special thanks to Erik Ramberg, Dario Menasce,
Lorenzo Uplegger, Dave Slimmer, Margaret Greaney,
Terry Tope, et al.
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In M-TEST Area
Glass mirror
MAPMTs
Gas tank C4F8O and Argon
Beam (120 GeV p)
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12 F-T boards mounted outside on the enclosure
12 pairs of MUX/FEH boards inside the
enclosure 10 had been used in data taking.
24 50 long cables
53 MAPMT Tubes mounted on baseboards in RICH
enclosure
6 pairs of PMC/PTA cards in PCI expansion box
Linux box running Pomone based DAQ
12 F-T boards
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First Ring Observedat 01/28/05 1315
This is a good ring with about 40 photon as
expected. Horizontally adjacent cells in one
MAPMT tube also have adjacent wires in cable,
adjacent traces in PCB and adjacent channels in
FEH ASIC.
Cross-talk between adjacent cells ?
Cross-talk or two real photon?
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Determination of HV Settings

• MAPMT tubes are divided into 3 groups according
  to their gain, and applied different HV.
• Definition two or more adjacent channels with
  hit form a cluster hit.
• The cluster hit may not correspond to only one
  photon, but with this treatment one can measure
  plateau.
• We decided to use 800/750/700 V as nominal HV.

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Cluster Size In HV Scan
Background
Beam
LED Pulser

• There are LEDs inside enclosure to generate
  light pulses. This is useful to study cross talk
  effect.
• We also took data with background (pure
  electronic noise and light leaks).
• With 800/750/700 V setting, most of cluster hits
  in beam data are due to photons hitting adjacent
  channels. Only 5 of total hits are due to
  cross-talk.

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Threshold Scan

• We use threshold DAC 121 (44 Ke) as nominal
  threshold. We also took good data at even lower
  threshold DAC125 (27 Ke).
• The detection efficiency is a smooth function of
  threshold as expected which is good.
• The last point is due to very low threshold that
  saturates the electronics.

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Parameter Determination
Fit these 3 parameters by minimizing
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Detector Alignment

• Mirror tilt angle is very close to the set value.
• Track inclination angle is close to zero
  indicating the quality of our initial mechanical
  alignment.
• Errors not are estimated yet.

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Detector Alignment Stability
Mirror adjusted deliberately
Over 100 hrs 1 mrad ring shifts by 1
pixel/cell
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Refractive Index
(preliminary)
Measurement at 412 nm using Michelson
interferometry
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Refractive Index Before Correction

• The index n is determined from the c2 fit.
• As function of run ID, the index roughly
  follows the trend of gas pressure.
• The pressure (P), temperature (T) and gas purity
  correction needs to be made.

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Single Photon Cherenkov Angle Resolution
s 0.75 mrad
s 0.79 mrad
MC
Data

• This is a single run with nominal setting.
• Cross talk and track direction dispersion
  contributes to the resolution in real data.

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Track Cherenkov Angle Resolution
Data
Data
Single track peak ltNgtData 43.1 ltNgtMC 40.5 The
difference is about 5, which is the same as
cross talk effect.
sData 0.118 mrad sMC 0.111 mrad
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Double Track Peak Issue
Single track peak ltNgt 43.1 s 6.5

• Number of hits in double track events is about
  10 lower than expectation.
• The deficit is due to well known photon overlap
  effect, which would seldom happen in a real
  experiment.
• This is proved in a simulation where we add hits
  from two real data single track events together.

ltNgt 76.9
ltNgt 86.2
Double track peak ltNgt 76.8 s 10.2
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Summary

• The DAQ system in phase II beam test works very
  well.
• With optimized baseboard voltage divider, FE bias
  setting the cross talk is reduced, while high
  efficiency in FE readout is maintained.
• Preliminary result shows that the photon yield
  and Cherenkov ring resolution is consistent with
  expectation.
• C4F8O is proved to be a suitable Cherenkov
  radiator.
• We have developed a new ASIC and presently
  characterizing a single chip hybrid. We are
  seeking financial support from FNAL to finish
  this RD.