Results from Cosmic Test.

Results from CSC ME234/2-001 Cosmic Test at Fermilab (June-July 2000).

Introduction.

- The data were taken on the cosmic muon test stand at Fermilab. Results below are mostly for anode TDC readout data.

Comparison with ALCT data will be given later.

Calibration.

ALCT calibration control of AFEB.

- ALCT provides two signals for AFEB calibration. First one is the test pulse like shown here (from the ASIC test stand).

The amplitude of the test pulse is controlled by the ALCT DAC code (see page 1 in ALCT with data obtained with digital scope).

Corresponding input charge Qin was calculated as Qin(fC) = DAC(mV) * Ccal where Ccal = 0.24 pF is the intrinsic injection

capacitance of the CMP16F ASIC. The irregularities in the difference between fit and data are due to change in scale of scope.

The fitted function DAC(mV) vs DAC code is

DAC(mv) = (0.202E+02) + (0.531E+01)*DAC + (0.124E-01)*DAC**2 - (0.976E-04)*DAC**3.

Better and simpler fit can be done if one can limit it to the region of Qin=0-100 fC. Note that Ccal and function DAC(mV)

vs DAC(code) must be measured and documented during mass production ASIC's and ALCT's tests for each ASIC chip

and each ALCT board.

- The second ALCT calibration signal provides voltage level to control AFEB's discriminators threshold. In DAQ software

JTAG code is used for this and one JTAG count corresponds to U(ALCT) ~ 9.5 mV (page 2 of ALCT). Then the threshold of

discriminator is Ud = Ubase - U(ALCT), where Ubase = 1550 - 1600 mV is the base voltage of the discriminator. Therefore

higher JTAC corresponds to lower threshold Qthr. Typically JTAG = 140 corresponds to the Qthr of 20 fC and 125 - to the

Qthr of 40 fC for ALCT and AFEB used during the test run. The U(ALCT) vs JTAG function must be specified for each ALCT

board and Ubase should be specified during mass production ASIC's test.

- The JTAG can be tuned for each anode board to get one and the same threshold for all boards (see Fig.1a and Fig.1b in the talk).

The noise rate, efficiency etc.

Chamber anode noise rate vs HV at Qthr = 20 fC.

- Noise rate per wire group at HV=3.6 kV (includes cosmic muon rate) (Rate per wire group)

- Averaged over wire groups noise rate (layer by layer) vs HV (includes cosmic muon rate)

(Aver. rate). There is no noise at HV = 0 kV.

Crosstalk between layers at Qthr=20 fC.

- The crosstalk was measured as a ratio of anode wire groups occupancies in the CSC layers 1,3,5 (2,4,6) having HV of 0

to the occupancies of corresponding wires in layers 2,4,6 (1,3,5) having HV of 3.4, 3.6, 3.8 and 3.9 kV. The trigger

was from vertical cosmic muon tracks. The results are given for ALCT and TDC hits. For the TDC the earliest hits

have been used (software provides only one hit from each ALCT channel).

- the wire group by group crosstalks vs HV for each layer are given here for ALCT and for TDC. For TDC data from even

planes the results do not look right (except at HV=3.9 kV).

- details are here for ALCT and for TDC where page 9 has averaged over wire groups crosstalks vs HV. At HV=3.6 kV

(nominal HV) the crosstalks between layers are less than 1%.

Anode front-end efficiency (TDC hits) vs HV at Qthr = 20 fC.

- Efficiency vs HV (eff_20 fC) layer by layer, all wire groups. Open circles - TDC hits, filled circles - ALCT hits.

- HV50 (HV for efficiency of 50% as a parameter of the fitted Gauss error function) (HV50_20 fC) vs wire group.

- Sigma (a parameter of the fitted Gauss error function) (Sigma_20 fC) vs wire group.

- Efficiency at mean HV50 and Qthr=20 fC Eff(mean HV50) vs wire group.

- Maximum efficiency (Max_eff_20 fC) vs wire group.

- Maximum efficiency (TDC only, different scale) (Max_eff_20 fC, TDC) vs wire group.

Anode front-end efficiency (TDC hits) vs HV at Qthr = 40 fC.

- Efficiency vs HV (eff_40 fC) layer by layer, all wire groups.

- HV50 (HV50_40 fC) vs wire group.

- Sigma (Sigma_40 fC) vs wire group.

- Maximum efficiency (TDC, ALCT) (Max_eff_40 fC) vs wire group.

- Maximum efficiency (TDC only, different scale) (Max_eff_40 fC, TDC) vs wire group.

Comparison of the anode front-end efficiencies (TDC hits) at Qthr = 20 fC and 40 fC.

- Efficiency vs HV (eff_20_40 fC) layer by layer, averaged over wire groups.

- Difference HV50(40 fC) - HV50(20 fC) vs wire group (eff_20_40 fC) layer by layer.

Cluster size vs HV at Qthr = 20 fC and 40 fC.

- The cluster size is defined as the number of adjucent wire groups with at least one hit in each of them. The minimum

length is 1 ("Single"), CL2 have two wire groups ON etc. Sometimes the layer in the event can have several

"Single" and/or CL2 etc. All of them are counted therefore sum of their fractions relatively to the number of muons

crossing the aperture of the chamber can exceed 100%. Each run had 10,000 events and about 53% of them are the muons

which go through the chamber. This fraction for each layer was defined at HV=3.6 kV where the chamber is 100% efficient.

The averaged over all six layers fractions of the clusters with different sizes vs HV are given here (cluster size).

The types of hits distributions in each layer (SINGLE, CL2, CL3 etc and MANY) are given in (types).

Time distributions (from TDC hits).

A drift time per plane at HV=3.6 kV.

- The residuals of the drift time relatively to the mean drift time (in each wire group) are plotted here.

Time distributions for the 1-st, 2-nd, 3-rd and 4-th hits (from 4 and more layers) at HV=3.6 kV.

- Events with only one vertical muon track were selected. The track was defined as a pair of hits in layers 1 and 6 in one

and the same wire group. The time distributions are here. The efficiency of having 4 and more hits in such track is 99.7 +- 0.1 %

The efficiency to be inside the 25 ns window vs window position for the 1-st, 2-nd, 3-rd and 4-th

hits (from 4 and more layers) at HV=3.6 kV.

- The maximum efficiency for the 2-nd hit is 96.2% and the corresponding range of 25 ns window positions for efficiency greater

than 92 % is 10 ns (plots).

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Last modified: Mon Sep 4 18:30:00 CST 2000 teren@fnal.gov