1. News on second coordinate readout
A. Piskun for the Dubna muon group
GSI, Darmstadt, 13 December 2011
Strip wave impedance for different strip configurations
Influence of high strip capacitance on the noise of FEE channel
Influence of high strip capacitance on signal shape
Test stand – imitation of RSP detector layer, real 60Co and cosmic strip signals

2. Strip wave impedance
Wave impedance is measured for strips of different width (1÷8 cm) and for different gaps (d= 0÷15 mm) between strip board and Fe plate of absorber structure
FEE input impedance = 46 Ohm
1cm width strip and gap of 15 mm are the most appropriate for the impedance match

3. Noise of double Ampl-8.3 vs strip capacitance
Strip capacitance varies in diapason 400 ÷ 1000 pF (depends on strip dimensions and gap between strip board and absorber plate)
Double Ampl-8.3 Amplification: Ka≈ 390 mV/uA
(A2DB-32 card was used)
C=0 pF noise r.m.s ≈ 12mV (~0,03uA)
C=500 pF (strip length ~1m) noise r.m.s ≈ 20mV (~0,05uA)
C=1000 pF (strip length ~ 2m) noise r.m.s ≈ 22mV (~0,05uA)
Average strip signal ~ 0,7uA
Noise caused by high strip capacitance is not a limiting factor for strip signal R/O

4. Influence of strip capacitance on signal shape
Input signal shape
(generator pulse: amplitude 100mV, width 100 ns)
The worst case: С=10000pF, 10 uA Input signal (equivalent to strips 8cm x 100cm)
Oscillograms of A2DB-32 analog output signal (inversed to input)
C = 0 pF
For 5 uA Input signal
For 1 uA Input signal

5. Influence of strip capacitance on signal shape
Oscillograms of A2DB-32 analog output signal (inversed to input)
C = 500 pF
For 5 uA Input signal
For 1 uA Input signal
C = 1000 pF
Low signals with high strip capacitance remain detectable

6. Scintillation counters telescope
Model of the Range System prototype detecting layer in Fe absorber gap (configuration assembled for study of real 1m long strip signals)
Scintillation counters telescope
Copper foil
(covers operational strips)
Strip board
60Co source
MDT layer
A-32
(hidden in the gap)
A2DB-32
HV/S cards
A2DB-32
Asum-96
“absorber plates”
(imitation based on fiber glass laminate boards)

7. Wire (waveform 1) and 1 m long strip (waveform 2) signals from 60Co source for 3 different positions of the source along the strip
MDT HV=2,4 kV, wire signals are used for triggering
Far end from strip FEE
Middle position
Close to strip FEE
No dependence of strip signal shape on distance from strip FEE to the area where the signal is induced was observed on the 1m long strips

8. Wire (waveform 1) and strip (waveform 2) signal accumulations from 60Co source for different MDT HV potentials
MDT HV =2.05kV
MDT HV =2.15kV
Counting rate (a) and efficiency (b) curves of the MDTs with the open and closed cathode geometries for cosmic rays at a threshold of 2.0 μA.
MDT HV =2.25kV
MDT HV =2.35kV
We expect to achieve the strip signal registration efficiency close to the one of the wire signal.

9. Characteristic strip signals (waveform 2) corresponding to wire signals (waveform 1) from cosmic for different MDT HV potentials
MDT HV potential =2.2kV
MDT HV potential =2.3kV
MDT HV potential =2.4kV
Triggering by scintillators telescope, wire signal – OR of 8 wires (output of ASum-96 => higher noise, halved wire amplitudes)
Wire (waveform 1) and strip (waveform 2) signal accumulations for cosmic (MDT HV potential = 2 .3kV)

10. Conclusion
Chosen configuration -1cm strip width and 15mm gap - proved to be optimal for matching of strip wave impedance and FEE input impedance
High strip capacitance is not a limiting factor for strip signal readout
Strip signals are detectable