View on the TOT option for CBM-XYTER (toward specs)

1. View on the TOT option for CBM-XYTER (toward specs) E. Atkin, I.Ilyushchenko, A.Kluev, Yu.Volkov, MEPhI A.Voronin, SINP MSU 13rd CBM Collaboration meeting, FEE section, 12.03.09

2. To present a status view of joint team (MEPhI/SINP MSU) on the CBM-XYTER FEE specs, relevant to TOT option Aim 13rd CBM Collaboration meeting, FEE section, 12.03.09

3. Starting points are: • - CBM XYTER wiki • - internet- some experience • Signal shape & equivalent circuit => DR • TOT option for CBM-XYTER. • Jitter. Transient noise view. • Statement of other problems • Two versions of data-driven architecture • On the way tasks & conclusions Outline 13rd CBM Collaboration meeting, FEE section, 12.03.09

4. The duration of the electron and hole pulses is determined by the time required to traverse the detector as in a parallel-plate detector, but the shapes are very different. H. Spieler. Front-End Electronics Systems for Particle Detection and Imaging – Signal Formation and Acquisition. 2008 IEEE Nuclear Science Symposium, p.8 Current pulses in strip detectors 13rd CBM Collaboration meeting, FEE section, 12.03.09

5. CBM strips are not micro, but long transmission lines … accurate matching with FEE via quality microcables (up to tens cm in length) needed Equivalent detector ckt. simplified(toward lumped model) 13rd CBM Collaboration meeting, FEE section, 12.03.09

6. Transient noise 2 mips Threshold 1 mip Effectivness improvement Signal dynamic range (SDD=2) 13rd CBM Collaboration meeting, FEE section, 12.03.09

7. Part of noisy 1 mip/threshold Threshold/base line noise LSB ~ 70..80% part of cluster goes to strip Other factors related to signal shape and amplitude (4÷6):1 (?):1 1:(0.7÷0.8)typ (?):1 From threshold (read LSB) to 2 mips (7.2 fC max) we should foresee 4-bit range We have quite rigit specs on the noise  accurate filtering needed How many ADC bits needed? 13rd CBM Collaboration meeting, FEE section, 12.03.09

8. Statistics of detector signals • Detector should be considered as a RF structure – long transmission line • Strips-FEE cabling (up to tens cm length) also looks like a transmission line which makes a delay and change a pulse shape • Radiation hard environment Very front-end tasks 13rd CBM Collaboration meeting, FEE section, 12.03.09

9. TOT methodically is a type of ADC and similar to Wilkinson (dual slope) one Pulse measurement process in Wilkinson ADC: What does the TOT option mean for CBM-XYTER? 13rd CBM Collaboration meeting, FEE section, 12.03.09

10. How to put threshold? 13rd CBM Collaboration meeting, FEE section, 12.03.09

11. Single slope TOT uses capacitor, charging by constant current source till the crossing of the signal falling edge • Direct TOT uses leading/falling edge comparator for time references • Schmidt trigger TOT (due to built-in hysteresis) uses lower threshold for the trailing edge triggering Three possible solutions for TOT 13rd CBM Collaboration meeting, FEE section, 12.03.09

12. Transient noise Jitter (transient noise example) 13rd CBM Collaboration meeting, FEE section, 12.03.09

13. Balistic deficit • Double sided read-out • Leakage current (DC mode) compensation versus noise • Type of shaping (CR-RCn and anti-tail/anti-alias) both for amplitude measurements and timing • Discriminator options (LE, CFD, ID) for timing • Discriminator charge sensitivity • All versus long-term radiation • All versus power consumption Detector signal family simulations needed Statement of other problems 13rd CBM Collaboration meeting, FEE section, 12.03.09

14. Mainstream solution is token-ring derandomisation Back-up architecture with cross-point switch is advantageous since it allows to perform a peak find function after derandomisation and therefore save power consumption Now the derandomiser chip based on 12816 cross-point switch under development (A.Kluev). Pipeline ADC (Yu.Bocharov/A.Simakov) is expected to be one of the built-in block TOT study will trend us to incorporate front-end test structures. Prototyping  late 2009.. beg. 2010 Two versions of data-driven architecture 13rd CBM Collaboration meeting, FEE section, 12.03.09

15. Direct agreements with Cadence and MG have signed for the next two years • Europractice membership & DKs updated • Expected are that 3 new PhD students for FEE development will be involved in the CBM FEE activity for 3 years starting from May 2009 • Other On the way tasks 13rd CBM Collaboration meeting, FEE section, 12.03.09

16. 1. S. Godowsky, M. Turala, et al. Pulse shapes of silicon strip detectors as a diagnostic tool. NIM A, 1993, Volume 326, Issue 1-2, pp. 239-242. • 2. P. Allport. Silicon strip detector designs for the ATLAS experiment. NIM A, vol. 386, 1997 pp. 109–116. • 3. R. Kollipara, A. Arodzero, J. Brau et al. Study of 18-cm long single-sided AC-coupled silicon microstripdetectors IEEE Trans. on NS, Vol. 42,  Issue 2,  April 1995 , pp.92 – 101. • 4. H. Spieler . Front-End Electronics Systems for Particle Detection and Imaging . Signal Formation and Acquisition. IEEE Nuclear Science Symposium, Dresden, 2008, p.8. • F. Goulding, D. Landis, Ballistic deficit correction in semiconductor detector spectrometers, IEEE Trans. on NS, vol. 35, issue 1, 1988, pp. 119-124. • DušanKollár,  Pulse processing and Analyses, DNP, FMFI UK Bratislava, www.dnp.fmph.uniba.sk/~kollar/je_w/el3.htm#5b Some references 13rd CBM Collaboration meeting, FEE section, 12.03.09

17. TOT option should be considered as an ADC block • - For amplitude measurements 4-5 bit (6 bit?) resolution ADC needed at lowest power consumption • Filtering is to be studied versus jitter and time walk taking into account other system problems • Different ways for power consumption minimizing is to be studied both at the block and architecture (system) level • Detector signal family (for both sides) is to be studied as well as multichannel equivalent circuits Some conclusions 13rd CBM Collaboration meeting, FEE section, 12.03.09