1. Mice VC Nov 2005Jean-Sébastien GraulichSlide 1 The ADC Problem in MICE o Reminder: Spill, Readout and Digitization o Acquisition Rate vs dead time o Conventional ADC vs Flash ADC o Stretcher and Sampling frequency o Commercial Flash ADCs o Charge measurement without ADC ?

3. Mice VC Nov 2005Jean-Sébastien GraulichSlide 3 Reminder  Main Requirement from the MICE proposal The aim is to collect data for 600 muons/Spill A spill is 850 µs long (flat top of the RF)  First Principle: Readout of Detector Data at the end of the Spill DAQ-trigger is given by the End of Spill Signal  Data for ~600 muons has to be buffered in the Front End Electronics Particle-trigger (or strobe) is given when a particle go through MICE  Digitization dead time will limit the number of muons we can collect

4. Mice VC Nov 2005Jean-Sébastien GraulichSlide 4 #events vs dead time  850 microsecond RF Flat top  Multiple events per burst rejected

5. Mice VC Nov 2005Jean-Sébastien GraulichSlide 5 ADC Flash ADC  Conventional ADC (currently on the market) 1 datum/ch = charge (~12 bits) Dead time > 2.8 µs w/o zero suppression Given by the conversion time Buffer size ~ 30 events Would be enough if zero suppression but then the Dead Time is longer  Flash ADC = Waveform digitizer The signal is digitized with given sampling frequency and resolution Many data points/ch (~ 12 bit each) Charge reconstructed by software Direct signal from PMt -> requires ~ 300 MHz Sampling f Dead time given by access to the buffer memory (<< µs) Buffer size: up to 1MSample/ch ~ 30 ns Gate ~ 100 ns Q

6. Mice VC Nov 2005Jean-Sébastien GraulichSlide 6 Stretcher  Problem 1: $ High frequency Flash ADC are expensive: 1000 EUR/ch  Problem 2: Data volume 20 samples/ch/muon No zero suppression (keep low dead time) 600 µ x 240 ch x 20 sample x 12 bits = 4.2 MB/Spill  Solution 1: Stretcher -> Reduce sampling frequency ~ 300 ns Stretcher V ~ Q

7. Mice VC Nov 2005Jean-Sébastien GraulichSlide 7 Commercial Flash ADCs  TPG (Alice) flash ADC looks out of specs Sampling frequency 10 MHz 1 kSample buffer (100 µs)  Commercial Flash ADC Struck SiS3300: 8 Ch, 1-100 MHz, 12-bit, 128 kSample/ch ~3500 EUR/board http://www.struck.de/sis3300.htm Hytec VTR2537: 8 Ch, 60 MHz, 12-bit, 1 MSample/ch < 4500 EUR/board http://www.hytec-electronics.co.uk/2537.html  Still expensive: ~ 500 EUR / ch  Still Large data size: ~ 2 MB/Spill (10 samples/signal)

8. Mice VC Nov 2005Jean-Sébastien GraulichSlide 8 Charge w/o ADC  Solution 2 (Thanks to Emilio Radicioni)  TDCs exist CAEN V767 and/or V1190 (128 ch/module !) < 50 EUR/ch 1 datum /ch -> ~ 350 kB/Spill (w/o zero suppression) Zero suppression comes for free !  Stretcher possible ? Resolution ? Time over Threshold ~ Q Stretcher Tot ~ Q TDC With ToT Th

9. Mice VC Nov 2005Jean-Sébastien GraulichSlide 9 Conclusion  Conventional ADC should be excluded  Flash ADC can be used but they are expensive  Maybe we can be smart and use only TDC  Expertise in electronics from Sofia is very welcome/valuable  I am only proposing ideas Don’t expect me to build the hardware