Mice VC Nov 2005 Jean-Sébastien Graulich Slide 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 ?

100 ns

Digitisation Dead time

Particle Trigger

Bursts ! IsisMicrostructure

224 nsShould be ~500 ns

1700 ns on average

Next Particle Trigger

SoS

DAQ gate

EoS~1 ms

DAQ Trigger

DAQ Event !

Particle Events !

“GoodEvent”

(TOF0xTOF1xTOF2)

RF Pulse1 ms

20 ms

Isis Beam Radius

MS

RF Trigger

Target Position

SPILL !

RF Cycle

1 secPULSE !

Mice VC Nov 2005 Jean-Sébastien Graulich Slide 3

ReminderReminder

Main Requirement from the MICE Main Requirement from the MICE proposalproposal

The aim is to collect data for 600 muons/Spill A spill is 850 µs long (flat top of the RF)

First Principle: First Principle: Readout of Detector Readout of Detector Data at the end of the SpillData at the end of the Spill

DAQ-trigger is given by the End of Spill Signal

Data for ~600 muons has to be Data for ~600 muons has to be buffered in the Front End Electronicsbuffered in the Front End Electronics

Particle-trigger (or strobe) is given when a particle go through MICE

Digitization dead time will limit the Digitization dead time will limit the number of muons we can collectnumber of muons we can collect

Mice VC Nov 2005 Jean-Sébastien Graulich Slide 4

#events vs dead #events vs dead timetime

850 microsecond RF Flat top850 microsecond RF Flat top Multiple events per burst rejectedMultiple events per burst rejected

0

100

200

300

400

500

600

700

800

0.00 1.00 2.00 3.00 4.00 5.00

Digitization dead time (micro sec)

Acq

uir

ed e

ven

ts/s

pil

l

600 kHz

1 MHz

Mice VC Nov 2005 Jean-Sébastien Graulich Slide 5

ADC <-> Flash ADCADC <-> Flash ADC

Conventional ADC Conventional ADC (currently on the market)(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 digitizerFlash 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

Mice VC Nov 2005 Jean-Sébastien Graulich Slide 6

StretcherStretcher

Problem 1: $ High frequency Flash ADC are Problem 1: $ High frequency Flash ADC are expensive: 1000 EUR/chexpensive: 1000 EUR/ch

Problem 2: Data volumeProblem 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 Solution 1: Stretcher -> Reduce sampling frequencyfrequency

~ 300 ns

StretcherV ~ Q

Mice VC Nov 2005 Jean-Sébastien Graulich Slide 7

Commercial Flash Commercial Flash ADCsADCs

TPG (Alice) flash ADC looks out of specsTPG (Alice) flash ADC looks out of specs Sampling frequency 10 MHz 1 kSample buffer (100 µs)

Commercial Flash ADCCommercial 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:Still expensive: ~ 500 EUR / ch

Still Large data size:Still Large data size: ~ 2 MB/Spill (10 samples/signal)

Mice VC Nov 2005 Jean-Sébastien Graulich Slide 8

Charge w/o ADCCharge w/o ADC

Solution 2 (Thanks to Emilio Radicioni)Solution 2 (Thanks to Emilio Radicioni)

TDCs existTDCs 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 ?Stretcher possible ? Resolution ? Resolution ?

Time over Threshold ~ Q

Stretcher

Tot ~ Q

TDCWithToT

Th

Mice VC Nov 2005 Jean-Sébastien Graulich Slide 9

ConclusionConclusion

Conventional ADC should be Conventional ADC should be excludedexcluded

Flash ADC can be used but they are Flash ADC can be used but they are expensiveexpensive

Maybe we can be smart and use only Maybe we can be smart and use only TDCTDC

Expertise in electronics from Sofia is Expertise in electronics from Sofia is very welcome/valuablevery welcome/valuable

I am only proposing ideasI am only proposing ideas Don’t expect me to build the hardware