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

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

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

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

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

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)

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

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.

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)

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