# Presentation: 669259

## Tackling the search forLepton Flavor Violationwith GHz waveform digitizing using the DRS chip

- Stefan Ritt
- Paul Scherrer Institute, Switzerland

## Agenda

- DRS2

- DRS3

- DRS1

- MEG Experiment searching
- for e  down to 10-13

- Fermilab

- Feb. 26th, 2008

## Motivation

- Why should we search for *** e *** ?

## The Standard Model

|  |  | Fermions (Matter) |  |  |
| --- | --- | --- | --- | --- |
|  |  |  |  |  |
| Quarks |  | u
up | c
charm | t
top |
|  |  | d
down | s
strange | b
bottom |
|  |  |  |  |  |
| Leptons |  | e
electronneutrino | 
muonneutrino | 
tauneutrino |
|  |  | e
electron | 
muon | 
tau |

| Bosons |  |  |
| --- | --- | --- |
|  |  |  |
| 
photon |  | Force carriers |
| g
gluon |  |  |
| W
W boson |  |  |
| Z
Z boson |  |  |

| Higgs*
boson |
| --- |

- *) Yet to be confirmed

- Generation      I             II            III

- Fermilab

- Feb. 26th, 2008

## The success of the SM

- The SM has been proven to be extremely successful since 1970’s
- Simplicity (6 quarks explain >40 mesons and baryons)
- Explains all interactions in current accelerator particle physics
- Predicted many particles (most prominent *W*, *Z *)
- Limitations of the SM
- Currently contains 19 (+10) free parameters such as particle (neutrino) masses
- Does not explain cosmological observation such as Dark Matter and Matter/Antimatter Asymmetry

- CDF

- Today’s goal is to look for physics beyond the standard model

- Fermilab

- Feb. 26th, 2008

## Beyond the SM

- Find New Physics

- Fermilab

- Feb. 26th, 2008

## Discovery: 1936 in cosmic radiation
Mass: 105 MeV/c2
Mean lifetime: 2.2 s

- Mass: 105 MeV/c2
- Mean lifetime: 2.2 s

**The Muon**

- Seth Neddermeyer

- Carl Anderson

- e

- -

- 

- W-

- e-

**≈ ****100%**

**0.014**

**< 10****-11**

- led to Lepton Flavor Conservationas “accidental” symmetry

- Fermilab

- Feb. 26th, 2008

## LFV and Neutrino Oscillations

- Neutrino Oscillations  Neutrino mass    	*** e ***  possible even in the SM

-  LFV in the charged sector is forbidden in the Standard Model

-  mixing

- Fermilab

- Feb. 26th, 2008

## LFV in SUSY

- While LFV is forbidden in SM, it is possible in SUSY

- ≈ 10-12

- Current experimental limit:  BR(  e ) < 10-11

- Fermilab

- Feb. 26th, 2008

## History of LFV searches

- Long history dating back to 1947!
- Best present limits:
- 1.2 x 10-11 (MEGA)
***Ti → eTi* < 7 x 10-13 (SINDRUM II)
*** → **eee* < 1 x 10-12 (SINDRUM II)
- MEG Experiment aims at 10-13
- Improvements linked to advancein technology

- 1940    1950     1960     1970     1980     1990     2000     2010

- 10-1

- 10-2

- 10-3

- 10-4

- 10-5

- 10-6

- 10-7

- 10-6

- 10-9

- 10-10

- 10-11

- 10-12

- 10-13

- 10-14

- 10-15

- MEG

**SUSY SU(5)**
- BR(*** **** e ***) = 10-13  ***Ti **** eTi* = 4x10-16BR(** * **** eee*) = 6x10-16

- cosmic 

- stopped 

-  beams

- stopped 

- Fermilab

- Feb. 26th, 2008

**Current SUSY predictions**

- “Supersymmetric parameterspace  accessible by LHC”

- W. Buchmueller, DESY, priv. comm.

- current limit

- MEG goal

- J. Hisano et al., Phys. Lett. B391 (1997) 341
- MEGA collaboration, hep-ex/9905013

- tan 

- Fermilab

- Feb. 26th, 2008

## Experimental Method

- How to detect *** e ***?

## Decay topology  e 

**e**

****

****

*************** ******e *********

- 180o

-  → e  signal very clean
- Eg = Ee = 52.8 MeV
-  e = 180o
- e and  in time

- 52.8 MeV

- 52.8 MeV

- 10

- 20

- 30

- 40

- 50

- 60

- E[MeV]

- N

- 52.8 MeV

- 10

- 20

- 30

- 40

- 50

- 60

- Ee[MeV]

- N

- 52.8 MeV

- Fermilab

- Feb. 26th, 2008

## “Accidental” Background

**e**

****

****

*************** ******e *********

- 180o

-  → e  signal very clean
- Eg = Ee = 52.8 MeV
-  e = 180o
- e and  in time

****** ****e ******

****** ****e ******

- Annihilation
- in flight

- Background

- Good energy resolution
- Good spatial resolution
- Excellent timing resolution
- Good pile-up rejection

- Fermilab

- Feb. 26th, 2008

## Previous Experiments

| Exp./Lab | Author | Year | Ee/Ee %FWHM | E/E %FWHM | te (ns) | e (mrad) | Inst. Stop rate (s-1) | Duty cycle (%) | Result |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| SIN (PSI) | A. Van der Schaaf | 1977 | 8.7 | 9.3 | 1.4 | - | (4..6) x 105 | 100 | < 1.0  10-9 |
| TRIUMF | P. Depommier | 1977 | 10 | 8.7 | 6.7 | - | 2 x 105 | 100 | < 3.6  10-9 |
| LANL | W.W. Kinnison | 1979 | 8.8 | 8 | 1.9 | 37 | 2.4 x 105 | 6.4 | < 1.7  10-10 |
| Crystal Box | R.D. Bolton | 1986 | 8 | 8 | 1.3 | 87 | 4 x 105 | (6..9) | < 4.9  10-11 |
| MEGA | M.L. Brooks | 1999 | 1.2 | 4.5 | 1.6 | 17 | 2.5 x 108 | (6..7) | < 1.2  10-11 |
| MEG |  |  | ? | ? | ? | ? | ? | ? | ~ 10-13 |

- Fermilab

- Feb. 26th, 2008

## Collaboration

- ~70 People (40 FTEs) from five countries

- Fermilab

- Feb. 26th, 2008

## Paul Scherrer Institute

- Fermilab

- Feb. 26th, 2008

## PSI Proton Accelerator

- Fermilab

- Feb. 26th, 2008

## MEG beam line

- +

- R ~ 1.1x108 +/s at experiment

-  ~ 10.9 mm

- e+

- +

- Fermilab

- Feb. 26th, 2008

## Liquid Xenon Calorimeter

- Calorimeter: Measure  Energy, Positionand Time through scintillation light only
- Liquid Xenon has high Z and homogeneity
- ~900 l (3t) Xenon with 848 PMTs(quartz window, immersed)
- Cryogenics required: -120°C ... -108°
- Extremely high purity necessary:1 ppm H20 absorbs 90% of light
- Currently largest LXe detector in theworld: Lots of pioneering work necessary

- 

****

- Fermilab

- Feb. 26th, 2008

- Use GEANT to carefully study detector
- Optimize placement of PMTs according to MC results

- Fermilab

- Feb. 26th, 2008

## The complete MEG detector

- Fermilab

- Feb. 26th, 2008

## Current resolution estimates

| Exp./Lab | Author | Year | Ee/Ee %FWHM | E/E %FWHM | te (ns) | e (mrad) | Inst. Stop rate (s-1) | Duty cycle (%) | Result |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| SIN (PSI) | A. Van der Schaaf | 1977 | 8.7 | 9.3 | 1.4 | - | (4..6) x 105 | 100 | < 1.0  10-9 |
| TRIUMF | P. Depommier | 1977 | 10 | 8.7 | 6.7 | - | 2 x 105 | 100 | < 3.6  10-9 |
| LANL | W.W. Kinnison | 1979 | 8.8 | 8 | 1.9 | 37 | 2.4 x 105 | 6.4 | < 1.7  10-10 |
| Crystal Box | R.D. Bolton | 1986 | 8 | 8 | 1.3 | 87 | 4 x 105 | (6..9) | < 4.9  10-11 |
| MEGA | M.L. Brooks | 1999 | 1.2 | 4.5 | 1.6 | 17 | 2.5 x 108 | (6..7) | < 1.2  10-11 |
| MEG |  | 2008 | 0.8 | 4.3 | 0.18 | 18 | 3 x 107 | 100 | ~ 10-13 |

- Fermilab

- Feb. 26th, 2008

## MEG Current Status

- Goal: Produce “significant” result before LHC
- R & D phase took longer than anticipated
- Detector has been completed by theend of 2007
- Expected sensitivity in 2008: 2 x 10-12                              (current limit: 1 x 10-11)

- http://meg.psi.ch

- Fermilab

- Feb. 26th, 2008

## Pile-up in the DC system

- Pile-up can severely degrade the experiment performance ( MEGA Experiment) !
- Traditional electronics cannot detect pile-up

- TDC

- Amplifier

- Discriminator

- Measure Time

- Need fullwaveform digitization
- > 100 MHz to reject pile-up

- Moving average baseline

- hits

- Fermilab

- Feb. 26th, 2008

## Beam induced background

- 108 /s produce 108 e+/s produce 108 /s

- Cable ductsfor Drift Chamber

- Fermilab

- Feb. 26th, 2008

## Pile-up in the LXe calorimeter

- n

- E[MeV]

- 50               51              52

- e

- radiativemuon
- decay

- t

- PMT
- sum

****

**(********e********)****2**** + ******

**e**

****

- 51.5 MeV

- 0.511 MeV

-  ’s hitting different parts of LXe can be separated if > 2 PMTs apart (15 cm)
- Timely separated ’s need waveform digitizing > 300 MHz
- If waveform digitizing gives timing <100ps, no TDCs are needed

- ~100ns

- Fermilab

- Feb. 26th, 2008

## Need 500 MHz 12 bit digitization for Drift Chamber system
Need 2 GHz 12 bit digitization for Xenon Calorimeter + Timing Counters
Need 3000 Channels
At affordable price

- Need 2 GHz 12 bit digitization for Xenon Calorimeter + Timing Counters
- Need 3000 Channels
- At affordable price

**Requirements summary**

- Solution: Develop own“Switched Capacitor Array” Chip

- Fermilab

- Feb. 26th, 2008

## The Domino Principle

- Shift Register

- Clock

- IN

- Out

- “Time stretcher” GHz  MHz

- Waveform
- stored

- Inverter “Domino” ring chain

- 0.2-2 ns

- FADC
- 33 MHz

- Keep Domino wave running in a circular fashion and stop by trigger  Domino Ring Sampler (DRS)

- Fermilab

- Feb. 26th, 2008

## Switched Capacitor Array

- Cons
- No continuous acquisition
- No precise timing
- External (commercial) FADC needed
- Pros
- High speed (~5 GHz) high resolution (~12 bit equiv.)
- High channel density (12 channels on 5x5 mm2)
- Low power (10 mW / channel)
- Low cost (< 100$ / channel incl. VME board)

- t

- t

- t

- t

- t

- Fermilab

- Feb. 26th, 2008

## Folded Layout

- Fermilab

- Feb. 26th, 2008

## “Tail Biting”

- enable

- 1

- 2

- 3

- 4

- 1

- 2

- 3

- 4

- speed

- Fermilab

- Feb. 26th, 2008

## Sample readout

- 0.2 pF

- 20 pF

- DRS1

- Tiny signal

- Temperature
- Dependence

- ~kT

- Fermilab

- Feb. 26th, 2008

## DRS3

- Fabricated in 0.25 m 1P5M MMC process(UMC), 5 x 5 mm2, radiation hard
- 12 ch. each 1024 bins,6 ch. 2048, ..., 1 ch. 12288
- Sampling speed 10 MHz ... 5 GHz
- Readout speed 33 MHz, multiplexedor in parallel
- 50 prototypes receivedin July ‘06

- Fermilab

- Feb. 26th, 2008

## VME Board

- 32 channels input

- General purpose VPC board built at PSI

- 40 MHz 12 bit FADC

- USB adapter
- board

- Fermilab

- Feb. 26th, 2008

## Bandwidth + Linearity

- Readout chain shows excellent linearity from 0.1V ... 1.1V @ 33 MHz readout
- Analog Bandwidth is currently limited by high resistance of on-chip signal bus, will be increased significantly with DRS4

**450 MHz (-3dB)**

**0.5 mV max.**

- Fermilab

- Feb. 26th, 2008

## Signal-to-noise ratio

- “Fixed pattern” offset error of 5 mV RMScan be reduced to 0.35 mV by offsetcorrection in FPGA
**SNR:**
- 1 V linear range / 0.35 mV = 69 dB (11.5 bits)

- Offset
- Correction

- Fermilab

- Feb. 26th, 2008

## 12 bit resolution

- 11.5 bits effective resolution

- <8 bits effective resolution

- Fermilab

- Feb. 26th, 2008

## Sampling speed

- PLL

- Reference
- Clock (1-4 MHz)

- Vspeed

**~200 psec**

- Unstabilized jitter: ~70ps / turn
- Temperature coefficient: 500ps / oC

- R. Paoletti, N. Turini, R. Pegna, MAGIC collaboration

- Fermilab

- Feb. 26th, 2008

## How far can we go?

- Maximal sampling speed with current technologies
- DRS4: 5.5 GHz in favor of linearity and flexibility
- 0.250 m technology maximum: 8 GHz
- 0.130 m technology maximum: 15 GHz
- Timing in O(10ps) region is tough
- Sampling has to be close to source (cable effect)
- TDCs can work in this region (vernier method), but what about discriminator?
- Probably only possible with analog sampling

- threshold level

- first
- electrons

- noise

- timing jitter

- Fermilab

- Feb. 26th, 2008

## Timing Reference

- signal

- 20 MHz
- Reference clock

- PMT hit

- Domino stops after
- trigger latency

- 8 inputs

- shift register

- Reference
- clock

- domino wave

- MUX

- Calibrate inter-cell t’s for each chip
- 200 ps uncertainty using PLL
- 25 ps uncertainty for timing relative to edge

- Fermilab

- Feb. 26th, 2008

## What timing can be obtained?

- Detailed studies by G. Varner1) for LAB3 chip
- Bin-by-bin calibration using a 500 MHz sine wave
- Accuracy after calibration: 20 ps

- 1) G. Varner *et al.*, Nucl.Instrum.Meth. **A583, **447 (2007)

- 1ns

- Fermilab

- Feb. 26th, 2008

## On-chip PLL

- PLL

- Reference
- Clock
- fclk = fsamp / 2048

- Vspeed

- On-chip PLL should show smaller phase jitter
- If <100ps, no clock calibration required

- loop filter

- DRS4

- Simulation:

- Fermilab

- Feb. 26th, 2008

## Comparison with other chips

|  | MATACQ D. Breton | LABRADORG. Varner | DRS3 |
| --- | --- | --- | --- |
| Bandwidth (-3db) | 300 MHz | > 1000 MHz | 450 MHz |
| Sampling frequency | 1 or 2 GHz | 10 MHz ... 3.5 GHz | 10 MHz ... 5 GHz |
| Full scale range | ±0.5 V | +0.4 ...2.1 V | +0.1 ... 1.1V |
| Effective #bits | 12 bit | 10 bit | 12 bit |
| Sample points | 1 x 2520 | 9 x 256 | 12 x 1024 |
| Channel per board | 4 | N/A | 32 |
| Digitization | 5 MHz | N/A | 33 MHz |
| Readout dead time | 650 s | 150 s  | 3 s – 370 s |
| Integral nonlinearity | ± 0.1 % | ± 0.1 % | ± 0.05% |
| Radiation hard | No | No | Yes (chip) |
| Board | V1729 (CAEN) | - | planned (CAEN) |

- Fermilab

- Feb. 26th, 2008

## Waveform Analysis

- What can we learn from acquired waveforms?

## On-line waveform display

- click

- template
- fit

- pedestal
- histo

- 848
- PMTs

- “virtual oscilloscope”

- Fermilab

- Feb. 26th, 2008

## QT Algorithm

**QT Algorithm**

- original
- waveform

- smoothed and
- differentiated (Difference Of Samples)

- Threshold in DOS

- Region for pedestal evaluation

- integration area

- t

- Inspired by H1 Fast Track Trigger (A. Schnöning, Desy & ETH)
- Difference of Samples (= 1st derivation)
- Hit region defined when DOS is above threshold
- Integration of original signal in hit region
- Pedestal evaluated in region before hit
- Time interpolated using maximum value and two neighbor values in LUT  1ns resolution for 10ns sampling time

- Fermilab

- Feb. 26th, 2008

## Pulse shape discrimination

- 

- 

- Leading edge    Decay time     AC-coupling       Reflections

- Fermilab

- Feb. 26th, 2008

## -distribution 

******-distribution **

- 

- 

-  = 21 ns
-  = 34 ns
- Waveforms can be clearly distinguished

- Fermilab

- Feb. 26th, 2008

## Coherent noise

- i Vi (t)
- All PMTs

- Pedestal
- average

- Charge
- integration

- Found some coherent low frequency (~MHz) noise
- Energy resolution dramatically improved by properly subtracting the sinusoidal background
- Usage of “dead” channels for baseline estimation

- Fermilab

- Feb. 26th, 2008

## Pileup recognition

- original

- derivative

- t = 15ns

- E1

- E2

- T 8ns

- T 10ns

- T 15ns

- T 50ns

- T 100ns

- MC simulation

- Rule of thumb: Pileup can be detected if T ~ rise-time of signals

- Fermilab

- Feb. 26th, 2008

## Crosstalk elimination

- Crosstalk removal by subtracting empty channel

- Hit

- Hit

- subtract

- Fermilab

- Feb. 26th, 2008

## Spurious Noise Problem

- Found “sometimes” a high frequency“ring” on all channels
- 40 MHz, ~20 mV, 1kHz repetition
- Finally identified the liquid xenonpump as the source
- This noise can screw up timingfor rare events
- Without waveform digitizing, thiswould have been very hard todebug

- Fermilab

- Feb. 26th, 2008

## Template Fit

- Determine “standard” PMT pulse by averaging over many events  “Template”
- Find hit in waveform
- Shift (“TDC”) and scale (“ADC”)template to hit
- Minimize 2
- Compare fit with waveform
- Repeat if above threshold
- Store ADC & TDC values

-  Experiment
- 500 MHz sampling

- Fermilab

- Feb. 26th, 2008

## High pass filtering

- originalwaveform

- template fit

- after optimized high pass FIR filter

- integration
- area

- Get rid ofbaseline (lowfrequency)noise
- Improveresolutionsignificantly

- Fermilab

- Feb. 26th, 2008

## Baseline Subtraction

- Latch

- Latch

- Latch

- Latch

- Latch

**Baseline Subtraction**

- Baseline
- Subtraction

- Latch

- 12 bit

- 100 MHz Clock

- 

- 

- 

- 

- -

- +

- <thr

- 

- +

- -

- Baseline
- Register

- Baseline
- subtracted
- signal

- LUT
- 12x12

- Calibrated and linearized signal

- Fermilab

- Feb. 26th, 2008

## Constant Fraction Discr.

- Latch

- Latch

- Latch

- Latch

**Constant Fraction Discr.**

- Latch

- 12 bit

- Clock

- 

- +

- +

- MULT

- Latch

- 0

- &

- <0

- Delayed
- signal

- Inverted
- signal

- Sum

- Fermilab

- Feb. 26th, 2008

## Data Reduction

- Zero suppression: hit if max. value > *n* x (baseline)
- Readout window: start / width in respect to trigger
- Pile-up flag: Zero-crossings of first derivation
- Re-binning 4:1, 8:1, 16:1
- ADC: Numerical integral of hit over baseline
- TDC: Only simple threshold (usable to recognize accidentals) and time-over-threshold

- MEG: Applying to 94% of 100 Hz data
- Keeping only 6 Hz of waveforms

**TOT**

**0.5 ns bins**

**4 ns bins**

- Fermilab

- Feb. 26th, 2008

## Huffman encoding

| Diff | Bin. Code |
| --- | --- |
| -1 | 00 |
| 0 | 01 |
| 1 | 10 |
| 2 | 11 |

| Diff | Bin. Code |
| --- | --- |
| 0 | 01 |
| 1 | 10 |
| 0 | 01 |
| -1 | 00 |
| 1 | 10 |
| 0 | 01 |
| 0 | 01 |
| -1 | 00 |
| 0 | 01 |
| 0 | 01 |

**0**

**1**

**-1**

**2**

**0.6**

**0.2**

**0.2**

**0**

**0.2**

**0.4**

**1**

| Huffman |
| --- |
| 110 |
| 0 |
| 10 |
| 111 |

| Huffman |
| --- |
| 0 |
| 10 |
| 0 |
| 110 |
| 10 |
| 0 |
| 0 |
| 110 |
| 0 |
| 0 |

- Fermilab

- Feb. 26th, 2008

## Where to perform waveform analysis?

- Switching from ADC/TDC to ~GHz waveform digitization increases amount of data by ~1000x
- Many algorithms suitable for on-board (FPGA) processing
- Charge integration and time estimation (“QT”)
- Zero-suppression, re-binning, Huffman encoding
- Basic pile-up recognition (zero-crossings of derivative)
- Algorithms for embedded CPUs or PC farms
- Inter-channel cross-talk removal
- Template fit (floating point)

- DRS

- FPGA

- Front
- End
- PC

- Off-line Analysis

- Fermilab

- Feb. 26th, 2008

## DAQ System Principle

- Active Splitter

- Drift Chamber

- Liquid Xenon Calorimeter

- Timing Counter

- Waveform
- Digitizing

- Trigger

- Trigger
- Event number
- Event type

- Busy

- Rack PC

- Rack PC

- Rack PC

- Rack PC

- Rack PC

**optical****link****(SIS3100)**

- Rack PC

- Rack PC

- Rack PC

- Rack PC

- Event Builder

- Switch

- GBit Ethernet

- LVDS parallel bus

- VME

- VME

- Fermilab

- Feb. 26th, 2008

## Multi-threading model

**Multi-threading model**

- VME
- Transfer
- Thread

- Calibration
- Thread

- Calibration
- Thread

- Calibration
- Thread

- Calibration
- Thread

- Collector
- Thread

- VME

- Round-Robin
- distribution

- Network

- Zero-copy ring buffers

- Fermilab

- Feb. 26th, 2008

**Optimal rate with 4 calibration threads**

- Fermilab

- Feb. 26th, 2008

## DAQ System

- Use waveform digitization (500 MHz/2 GHz) on **all** channels
- Waveform pre-analysis directly in online cluster (zero suppression, calibration) using multi-threading
- MIDAS DAQ Software
- Data reduction: 900 MB/s  5 MB/s
- Data amount: 100 TB/year

**2000 channels****waveform digitizing**

**DAQ cluster**

- Fermilab

- Feb. 26th, 2008

## Advanced Topics

- Reduced dead time, integrated triggering

## “Residual charge” problem

- R

- “Ghost pulse”
- 2% @ 2 GHz

- After sampling a pulse, some residual charge remains in the capacitors on the next turn and can mimic wrong pulses

- Implemented
- in DRS4

- Fermilab

- Feb. 26th, 2008

## ROI readout mode

**ROI readout mode**

- readout shift register

- Trigger

- stop

- normal trigger stop after latency

- Delay

- delayed trigger stop

- Patent pending!

- 33 MHz

- e.g. 100 samples @ 33 MHz  **3 us** dead time(2.5 ns / sample @ 12 channels)

- Fermilab

- Feb. 26th, 2008

## Daisy-chaining of channels

- Channel 0 – 1024 cells

- Channel 1 – 1024 cells

- Channel 2 – 1024 cells

- Channel 3 – 1024 cells

- Channel 4 – 1024 cells

- Channel 5 – 1024 cells

- Channel 6 – 1024 cells

- Channel 7 – 1024 cells

- Domino Wave Generation

- DRS4 can be partitioned in: 8x1024, 4x2048, 2x4096, 1x8192 cells

- 1

- 0

- 1

- 0

- 1

- 0

- 1

- 0

- Fermilab

- Feb. 26th, 2008

## Interleaved sampling

- delays (200ps/8 = 25ps)

- 5 GSPS * 8 = 40 GSPS

- Fermilab

- Feb. 26th, 2008

## “Almost” Dead time free system

- CMC1

- CMC2

- 32 channel

- 16 channel

- MUX

- VME board

- One board is active while other board is read out

- Fermilab

- Feb. 26th, 2008

## DRS4 packaging

- DRS3

- DRS4

- 9 mm

- 18 mm

- 5 mm

- DRS4
- flip-chip

- Fermilab

- Feb. 26th, 2008

## New generation of FADCs

- 8 simultaneous flash ADCs on one chip
- Requiredifferentialinput
- DRS4 has beenredesigned withdifferentialoutput

- Fermilab

- Feb. 26th, 2008

## Trigger an DAQ on same board

- Using a multiplexer, input signals can simultaneously digitized at 65 MHz and sampled in the DRS
- FPGA can make local trigger(or global one) and stop DRSupon a trigger
- DRS readout (5 GHz samples)though same 8-channel FADCs
- Multiplexer will be included in DRS4

- analog front end

- DRS

- FADC12 bit
- 65 MHz

- FPGA

- trigger

- LVDS

- SRAM

- global trigger bus

- No splitter (signal quality!), no dedicated trigger boards, no dedicated scalers

- Fermilab

- Feb. 26th, 2008

## “Redefinition of DAQ”

- Because of the high channel density of the DRS system, it becomes affordable to use waveform digitizing in experiments which today use ADC/TCDs

| Conventional | New |
| --- | --- |
| AC coupling | Baseline subtraction |
| Const. Fract. Discriminator | DOS – Zero crossing |
| ADC | Numerical Integration |
| TDC | Bin interpolation (LUT)
Waveform Fitting |
| Scaler (250 MHz) | Scaler (50 MHz) |
| Oscilloscope | Waveform sampling |
| 400 $ / channel | 100 $ / channel |

- FADC

- FPGA

- CPU

- DRS

- ~GHz

- ~100
- MHz

- Fermilab

- Feb. 26th, 2008

## Availability

- DRS4 will become available in larger quantities in summer ’08
- Chip can be obtained from PSI on a “non-profit” basis
- Delivery “as-is”
- Reference design (schematics) from PSI
- Costs ~ 10-15$/channel
- Costs decrease if we find sell more...
- Full VME board can be purchased from CAENprobably end of ’08 with firmware forpeak sensing ADC, QDC, ...
- Struck, others, ... ?

- Fermilab

- Feb. 26th, 2008

## Other experiments using DRS

- MACE TelescopeIndia

- PET scanners

- BPM for XFEL@PSI

- 8 chn.with
- PGA

- Magic Telescope, Canary Islands

- Fermilab

- Feb. 26th, 2008

## Conclusions

- Switched Capacitor Array techniques has prospects to trigger a quantum step in data acquisition
- The DRS chip has been designed with maximum flexibility and can therefore be used in many applications
- Collaboration on a scientific basis is very welcome

- http://midas.psi.ch/drs

- Datasheets, publications:

- Fermilab

- Feb. 26th, 2008