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,

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

Outline 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

Current pulses in strip detectors 13rd CBM Collaboration meeting, FEE section, 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 IEEE Nuclear Science Symposium, p.8

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

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

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

Very front-end tasks 13rd CBM Collaboration meeting, FEE section, 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

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

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

Three possible solutions for TOT 13rd CBM Collaboration meeting, FEE section,  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

Jitter (transient noise example) 13rd CBM Collaboration meeting, FEE section,

Statement of other problems 13rd CBM Collaboration meeting, FEE section, Balistic deficit Double sided read-out Leakage current (DC mode) compensation versus noise Type of shaping (CR-RC n 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

Two versions of data-driven architecture 13rd CBM Collaboration meeting, FEE section, 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 beg Mainstream solution is token-ring derandomisation

On the way tasks 13rd CBM Collaboration meeting, FEE section, 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 Other

Some references 13rd CBM Collaboration meeting, FEE section, 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 P. Allport. Silicon strip detector designs for the ATLAS experiment. NIM A, vol. 386, 1997 pp. 109– R. Kollipara, A. Arodzero, J. Brau et al. Study of 18-cm long single- sided AC-coupled silicon microstrip detectors IEEE Trans. on NS, Vol. 42, Issue 2, April 1995, pp.92 – H. Spieler. Front-End Electronics Systems for Particle Detection and Imaging. Signal Formation and Acquisition. IEEE Nuclear Science Symposium, Dresden, 2008, p.8. 5.F. Goulding, D. Landis, Ballistic deficit correction in semiconductor detector spectrometers, IEEE Trans. on NS, vol. 35, issue 1, 1988, pp Dušan Kollár, Pulse processing and Analyses, DNP, FMFI UK Bratislava,

Some conclusions 13rd CBM Collaboration meeting, FEE section, 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