Update on the RICH Beamtest 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 Jianchun Wang 03/11/05 BTeV Collaboration meeting

Phase II Beamtest (01/10/05-01/31/05) Special thanks to Erik Ramberg, Dario Menasce, Lorenzo Uplegger, Dave Slimmer, Margaret Greaney, Terry Tope, et al.  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.

In M-TEST Area MAPMTs Beam (120 GeV p) Glass mirror Gas tank: C 4 F 8 O and Argon

53 MAPMT Tubes mounted on baseboards in RICH enclosure 12 pairs of MUX/FEH boards inside the enclosure 10 had been used in data taking. 12 F-T boards mounted outside on the enclosure 24 50’ long cables 12 F-T boards 6 pairs of PMC/PTA cards in PCI expansion box Linux box running Pomone based DAQ

First Ring Observed at 01/28/05 13:15 Cross-talk between adjacent cells ? Cross-talk or two real photon? 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.

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.

Cluster Size In HV Scan Beam Background 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.

Threshold Scan  We use threshold DAC = 121 (44 Ke) as nominal threshold. We also took good data at even lower threshold DAC=125 (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. Thr. ~ 27 Ke Thr. ~ 44 Ke

Mirror tilt angle Beam inclination angle Refractive index Fit these 3 parameters by minimizing: Parameter Determination

 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. Detector Alignment mrad  1.15 mrad

Detector Alignment Stability Mirror adjusted deliberately Over ~ 100 hrs 1 mrad ~ ring shifts by 1 pixel/cell

Refractive Index n= (preliminary) Measurement at 412 nm using Michelson interferometry

Refractive Index Before Correction  The “index” n is determined from the  2 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.

Single Photon Cherenkov Angle Resolution  This is a single run with nominal setting.  Cross talk and track direction dispersion contributes to the resolution in real data.  ~ 0.79 mrad  ~ 0.75 mrad Data MC

Track Cherenkov Angle Resolution  Data = mrad  MC = mrad Data Single track peak Data = 43.1 MC = 40.5 The difference is about 5%, which is the same as cross talk effect.

Double Track Peak Issue Single track peak = 43.1  = 6.5 Double track peak = 76.8  = 10.2 = 86.2 = 76.9  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.

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.  C 4 F 8 O 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 R&D.