Department of Electronics - IPN - IN2P3

Department of Electronics - IPN - IN2P3

General & technical departments

Deparrttmentt off Electtrroni


Contact : P. Edelbruck tél. +33 1 69 15 74 74 (

Le Service d’Electronique Physique

Le Service d’Electronique Physique a pour mission le développement et la construction d’équipements de mesure et

d’acquisition de données. De nombreux instruments ne sont pas disponibles sur le marché et doivent être conçus et

réalisés à la demande, en vue d’équiper les détecteurs très particuliers de la physique nucléaire. L’activité du

service couvre toutes les phases du développement, depuis l’expression du besoin jusqu’à la fourniture « clé en

main » d’un appareil ou d’un sous-ensemble. Le service comprend 25 personnes dont une douzaine d’ingénieurs

intégrés à des équipes projets. Un groupe est chargé de la conception électromécanique et du développement des

circuits imprimés. Un atelier doté d’une structure d’achat est chargé de la construction des prototypes et de la

sous-traitance des productions en volume. Ces deux dernières années ont vu l’aboutissement de projets importants

dont un détecteur de particules chargées (MUST II) doté d’un ASIC développé avec le CEA. Le détecteur de muons

du projet Alice (10 6 voies) est maintenant en production et le détecteur germanium de grand volume AGATA est en

plein développement avec la perspective de construction de plusieurs milliers de cartes au nouveau standard ATCA.

Mission of the Group

The Electronics Group is composed of 25 persons,

including 12 electronics engineers. Its mission is the design

and the development of electronic equipments associated to

nuclear physics detectors. The activities are centred on

front-end electronics i.e. preamplifiers and signal

conditioning. The tasks range from spectroscopy,

calorimetry and tracking, using charge or energy

measurements for all kind of detectors (gas,

semiconductors, scintillators, PMDs…) to accurate timing

determination using analog and digital circuitry. The group

designs and manufactures complex digital interfaces

between the physics world and the acquisition systems.

From a manufacturing point of view, the group is in charge

of the delivery of the complete system. This is achieved

either using the internal workshop or subcontracting the

manufacturing task to industrial companies. The workshop

provides the necessary means for prototyping and repair

tasks in all cases. Due to the increase of the channel count

and complexity of most modern detectors, instrumentation

often requires the use of custom designed integrated

circuits. A special team with the appropriate design tools

exists for this purpose. Several components have been

successfully designed and manufactured, in collaboration

with other institutes (MUST with CEA) or internally (TDC

for G0, Analog pipe-line for AZ4π).

Teams & Organization

The department has two permanent entities working for all

projects : Design and Workshop. The rest of the staff is

organized in project teams, usually lead by a physicist in

the scope of a physics research project. This organization

changes over time, according to needs. With four persons,

the Design Group is in charge of the “electromechanical”

design of the instruments. Most of the work consists of

printed circuit board design. Three persons with

workstations and Cadence CAD tools are allocated fulltime

to this task. They also take care of the internal

component data base, with a permanent worry of making

manufacturing easy, safe and cost effective. Last but not

least the team is responsible of blueprints production for

manufacturing, of primary importance when the work is

subcontracted. A team of five persons is in charge of

hardware manufacturing and maintenance. Most of the

prototypes of the electronic boards are assembled

internally. Two persons are especially skilled in Surface

Mount Device assembling and repair. A new machine for

repairing Ball Grid Array packages (BGA) has been bought

in 2005. The team also takes care of the management of

external fabrication when quantities are large or a special

technology is required. In the later case, they select the

manufacturer, place the order and provide a total follow up.

ASIC Design

Although belonging to project teams, two engineers are

especially trained in silicon integrated circuits design. The

most recent development is an analog pipeline circuit

aimed to high speed signal sampling. The group has also

provided the design of the analog section of the recent

MUST II chip built in collaboration with CEA (see article

in this issue). The team also contributes to the IN2P3

“0.35μ building block club”. The objective of this

organization is to allow the whole community to reuse fully

documented designs issuing from larger systems designed

in the laboratories. Two original basic bricks have been

submitted so far (Delay Locked Loop and High Speed



The electronics for the large muon detector of ALICE (10 6

channels) has now entered its production phase. MUST II is

also completed and the production of 6 units has started.

The AZ4π project represents the R&D phase of the design

of a future charged particle detector (FAZIA) comprising

8000 channels and covering a 4π solid angle. The challenge

here is to perform Charge/Mass identification at high

energy, with high Z nuclei. A special high speed ASIC has

been designed for this purpose. The large volume

germanium detector AGATA will be tested in 2006 with an

electronic system developed with CSNSM and using the

new high speed communication standard ATCA.

- 141 -

General & technical Departments

The electtrroni

ics off ALIICE dimuon ttrracki ing chamberrs

IPNO Participation : V. Chambert, P. Courtat, S. Drouet, B.-Y. Ky, J-M. Martin, C. Oziol

Collaboration : Institut de Physique Nucléaire d’Orsay, Saha Institute of Nuclear Physics, Istituto

Nazionale di Fisica Nucleare Sezione di Cagliari, Subatech Nantes

L’électronique des chambres à fils du bras Dimuon d’Alice

Le bras Dimuon de l’expérience Alice du Cern comprend entre autres un système de reconstruction de traces des

particules composé de 10 chambres à fils reparties dans 5 stations. L’IPNO a en charge la coordination de

l’électronique pour tout le bras Dimuon, ainsi que la construction de la station 1. Le système de lecture des

chambres comprend des cartes frontales de lecture et de numérisation des données, des bus de transmission vers

les châssis CROCUS de lecture et un châssis de transmission et de mise en forme du trigger. Après une brève

présentation de ces systèmes nous décrirons de façon plus détaillée le système CROCUS.

Electronics architecture

The ALICE dimuon arm is, for the main parts, composed of

several absorbers, of a trigger system, of a dipole and of a

tracking system. The tracking system is composed of five

stations with two chambers for each of them.

IPN Orsay is in charge of the electronics coordination for

the tracking system (fig 1). It means that front-end

electronics (≈20 000 Manu boards, more than 10 6 channels),

CROCUS read out crates (≈ 22 crates), trigger dispatching

crates (2 crates) and the related software were designed at

Orsay and we will produced for the whole Dimuon


Besides these elements, data bus transmission (bus patch)

were designed at Orsay but each station adapted the system

for its needs and produced them.

Orsay is also responsible for the design and production of

transmission boards called translators and bridges both for

station 1 and 2.

CROCUS crate

A rough estimation of the typical information

number to read in the case of a “mean” collision gives

about 150 kB distributed in the five stations. Using a safety

factor of 2, the electronics will have to handle an

acquisition rate of 1200 evts/s for the lead beams and of




2 x 32



Up to 26 or 3 x 17


Up to 100 PATCH BUS

per detector.




DETECTOR: Chapter 1

FEE: Chapter 2

MANU: Chapter 2.1

READ OUT: Chapter 3

DISPATCHING: Chapter 3.2

CROCUS: Chapter 3.3

SOFTWARE: Chapter 3.4

LOW VOLTAGE: Chapter 4



EMC: Chapter 7







10 Meter max

Ribbon cable



Up to 50 PATCH BUS connected.



Optical link:


100 meter.




Ribbon cable

40 meter


One crate for all



Link to download:


DSP code.

From CTP

Trigger information:

L0, L1…..


- Monitoring.

- Stand alone DAQ.

- Test configuration.

fig 1:

2000 evts/s for the high intensity Ca beams.

- 142 -

The choice has been done to use DSP AD21160M (Digital

Signal Processor) farms to achieve the data readout coming

from the FEE. These DSPs are gathered in « clusters » in 20

specific crates called CROCUS (Cluster Read Out

Concentrator Unit System). Each crate is composed of 5

cards called « frontal » directly connected to the Patch

buses by ribbon cables and of a concentrator card which

collects the data coming from all the frontal cards then,

after, formatting, transmits them to the SIU (Source

Interface Unit) which will achieve the transmission towards

the DDL (Detector Data Link) (fig 1). This modularity

provides a high readout speed and minimizes the

General & technical Departments

consequences of a malfunctioning of an element. Moreover,

the use of all these DSPs permits the buffering of events at

different levels in the readout chain.

Each CROCUS crate has many functions :

- it picks up the detectors data, it concentrates them, it

sends them to the DAQ

- it generates the Front-end control signals and send

them to the front-end through buses

- it picks up trigger signals from dispatching crate and it

broadcasts them to the Front-end electronics

- It generates calibration signals, it sends them to the

detectors, and it processes the calibration data and it

sends them to the DAQ

- It detects failures on the read out chain

The production of the 22 crates is foreseen for 2006.

The very complex software design is in progress

All the CROCUS crates are close to the detector (less than

10 meters) to insure a good efficiency of the data

acquisition through 8 bits/ 20Mo/s linkport. The crate itself

is a specific one VME 6U 9T, amagnetic aluminum made,

very compact to be easily integrated on the detector.

The CROCUS architecture concentrates data with the

following scheme :

- each CROCUS frontal board (CROCUS_FRT) receives

data from 10 buses and it concentrates them within 2

front-end DSP.

- All the front-end DSP (10 for a CROCUS crate) are

connected through the back plane (CROCUS_back) to

2 DSP called concentrators located. Each connection is

done with a linkport.

- The concentrator DSP are located on a concentrator

board called CROCUS_CRT.

- A master DSP located on CROCUS_CRT gathers all

the data via a parallel bus 320MB/s and sends them

through a Xilinx FPGA to the SIU unit

- The SIU unit transmits data to ALICE DAQ with an

optical fiber.


Fig 2 : CROCUS crate prototype


are designed. Their integration in the specific crate is in


[1] The electronics of ALICE dimuon tracking chamber PRR


- 143 -

General & technical departments

The ASIIC developmentt actti ivitti

ies off tthe Electtrroni

ics Grroup

IPNO Participants : J.-C. Cuzon, S. Drouet, P. Edelbruck, E. Wanlin

Les activités de développements d’ASICS du Service d’Electronique Physique

Les détecteurs développés dans le domaine de la physique nucléaire embarquent aujourd’hui une instrumentation

de plus en plus complexe qui peut parfois comporter plusieurs millions de voies de mesure. Les niveaux de

précision requis, les volumes de données, la complexité des traitements effectués en ligne et les vitesses de

transfert conduisent fréquemment à abandonner les technologies d’électronique traditionnelle (discrète) et à

recourir aux techniques d’intégration sur silicium. Le Service d’Electronique Physique de l’Institut est engagé dans

cette voie depuis de nombreuses années et possède à son actif des réalisations importantes. On peut citer un

circuit de mesure de temps (TDC) destiné à la spectrométrie de masse, une chaîne de mesure pour les détecteurs

au silicium développée en collaboration avec le CEA et dernièrement une mémoire analogique rapide destinée à la

numérisation de signaux à très grandes vitesses. Le savoir-faire acquis par le groupe dans le domaine du

développement d’ASIC est aujourd’hui significatif et les outils informatiques disponibles permettent d’aborder le

développement de circuits analogiques-numériques complexes.

The complexity of the electronic equipment embedded in

nuclear physics detectors is becoming quite complex in

terms of technical specifications but also in terms of

channel count. A detector may comprise several millions of

electronic channels. The required precision level, the

volume of data and the complexity of the processing

performed online often leads to move from traditional

discrete technology to integrated solutions. The Electronics

Group of the Institute has started integrating designs many

years ago and several components have been developed.


I) was instrumented in the early 90’s with discrete

electronics. The second generation detector had several

hundreds of channels and clearly required an integrated

solution. A collaboration team was set up between IPN and

CEA for the design of an ASIC. The aim was to come up

with a chip performing timing and energy measurements

for 16 channels in a single chip (preamplifier, trigger,

shaper, time to analog converter and data read-out). The

preamplifier, the energy section and the logic interfaces

were designed at IPN and the timing and the multiplexing

modules at CEA.

The first achievement was a chipset aimed to mass

spectroscopy. The issue at this time (mid 90’s) was more of

a technical nature. The requirement was to measure time

intervals with a resolution better than 0.25 ns and a very

high repetition rate (multi-hit). Less than 20 ns may have

elapsed between two successive events. These features

were absolutely not achievable with commercial

components and have led to the design of two original

ASICs. The development has been performed using a

bipolar technology from the French silicon founder

Thomson. It was a success and the chips have been used in

a wide range of instrument during 10 years. They represent

the heart of CTN, a module aimed to mass spectroscopy,

now in use in many laboratories worldwide, as well as

COMET, a general purpose acquisition board used at

Tandem and CERN. They have also been implemented in

TOHR, a high resolution instrument for nuclear biology

research and recently in G0, an experiment in hadronic

physics (TJNAF-USA).


Many experiments in nuclear physics use detectors

sensitive to charged particles. Semi-conductor devices are

very well suited for this purpose and allow for a precise

measurement of energy, time and position. Position

measurements are using matrix of silicon detectors with

high channel counts. The first detector of this kind (MUST

- 144 -


View of the ASIC MAR

Another field rapidly developing in nuclear instrumentation

is the digital pulse shape analysis of signals issued by

General & technical departments

detectors of many kinds. These techniques can be used for

the localization of an interaction within a crystal

(Germanium) and for the mass over charge discrimination

of the incoming particle (silicon or scintillators). Off the

shelf fast flash ADCs can be used directly when the signals

are reasonably slow. With faster signals, the analog to

digital conversion cannot be performed directly. One way

to overcome this difficulty is to sample and store the fast

signal in a high speed analog memory (pipeline) and to

“replay” the portion of interest at a lower rate, allowing for

the use of a conventional flash ADC. The technique is

called FISO (Fast In - Slow Out). Although such methods

are now well known, no component is available on the

market place. The technique is clearly relevant for the

AZ4π R&D program and the design of such an analog

pipeline was decided.

The recording device is composed of a matrix of 1240

analog storage cells. Each cell is written in turn, with a time

interval of 0.5 ns. The matrix is handled as a ring buffer,

i.e. writing is performed continuously, overwriting the

older cells, until the process is stopped by a trigger signal.

The content is then frozen and the stored voltages can be

read out through a read bus.

successfully tested. 25 units have been packaged and will

been used to build up a first set of prototype boards for the

actual detector. However, a few flaws have been detected

and corrections will be performed. A new prototype will be

submitted to the founder at the beginning of 2006

The fast amplifier

Several building blocks had to be especially designed for

this application:

- The storage cell itself, composed of a capacitor

associated to very accurate switching devices

- The delay-locked-loop, an element delivering the 0.5

ns time interval

- The read and write amplifiers, with a bandwidth as

large as 350 MHz and high slew rate

- The logic of the whole system.

The building blocks were designed in such a way that they

can be reused later, even for a different application.

Furthermore, two of them were made available to the entire

IN2P3 community through the special “club 035” structure

started in 2004.

The amplifier test chip


The delay-locked-loop

The blocks were first manufactured as single elements in

special test chips and tested. The entire design has then

been assembled and the complete chip manufactured

beginning of 2005. The circuit was functional and has been

The Department of Electronics has now built up a valuable

experience in ASIC design. Skilled engineers doted with

powerful CAD tools are available within the Institute.

Numerous physics project can and will use these techniques

in the future. They will benefits in both the increase of the

performance level (precision, energy and timing

resolutions) and the complexity level : complex signal

processing over millions of channels.

- 145 -

General & technical departments

MAR :: An asic fforr tthe ffastt digittal


ion off currrrentt signals

IPNO Participation : J.-C. Cuzon, S. Drouet, P. Edelbrück, L. Leterrier, E. Wanlin

MAR : un asic pour la numérisation rapide des signaux de courant

Développé il a 4 ans, le préamplificateur à grande vitesse PACI offre une image précise du processus de collection

de charge d'un détecteur de silicium. Ce signal peut être employé pour la discrimination en Masse/Energie dans ce

type détecteur, en utilisant des techniques de filtrages numériques. Comme aucun composant du commerce ne

s’adapte à nos contraintes, nous avons décidé de concevoir un circuit intégré (asic) d’une mémoire analogique

(MAR) qui échantillonne le signal à très grande vitesse (jusqu'à 2 GSPS) avec la possibilité d’être lue à une vitesse

inférieure (50 MSPS) en employant un ADC du commerce. La profondeur de stockage de cette mémoire est

d’environ 1240 échantillons, avec une vitesse d'écriture réglable (de 100MSPS jusqu’à 2GSPS). Après l’étape de la

conception et du dessin physique, le layout a été envoyé chez le fondeur (AMS) en décembre 2004 et nous avons

reçu 25 puces encapsulées en mars 2005. Actuellement nous sommes en train de tester les performances et

fonctionnalités de cet asic MAR dans le but de réaliser une carte d’acquisition rapide.


Four years ago, the Electronics group developed a new

version of charge preamplifier called PACI having an

additional output of which the signal is a faithful

representation of the current pulse. The knowledge of the

shape of this pulse makes possible to obtain additional

information (A, Z...) in order to improve discrimination.

Accordingly, the electronics group is designing and

realizing a fast acquisition system allowing to digitalize the

output current signal of a preamplifier PACI. These current

signals have the following time characteristics: minimum

rise time of 2-3ns, duration of the impulse of few 10ns to


Considering the minimum rise time, the digitalization

system must be very fast, more than 1GSPS (giga samples

per second). Knowing that the very fast converters (>

1GSPS) available in the market do not correspond to our

application (too high dissipation, high price, 8 bits of

resolution), the SEP decided to develop a ASIC which

memorize the current signal at 2GSPS in an analog way.

on one of the DLL, this one is lower than 10ps rms. The

average value of one delay is 502ps.

When the analog levels of input current signal are

memorized in the asic, all the samples are sent to an analogto-digital

converter with a sampling frequency of 50MSPS

and with 12bits resolution. The digitized samples are then

processed by a FPGA realizing a digital processing of the


The diagram below represents the test bench which permits

to characterize the MAR asic.

Presentation of the asic MAR

This ASIC called MAR (Fast Analog Memory = Mémoire

Analogique Rapide) is based on an analog pipeline structure

storing the samples in an analog circular buffer. The aim of

this memory is to memorize in an analog way the current

signal coming from the detector via the PACI preamplifier.

This analog signal is sampled at 500ps (2GSPS) by the

1239 memorizing cells made of capacitors and MOS

switches. Thus, this memory can store a 619.5ns signal

when the time base is 500ps.

In the asic, the 1239 cells are placed in matrix form : 59

lines by 21 columns. Thus, each line contains 21 memory

cells. This dimension was not taken randomly : thanks to

this one, the asic can sample the signal with various time

Fig. 2 : Photo of the test bench with the asic MAR

bases without having time distortion. The following time

bases are available : 500ps, 1ns, 2ns, 5ns and 10ns.

Features of the asic MAR

It is important to note that each line is made up of 21 • Built in 0.35µm CMOS technology by AMS

memory cells and a DLL (Delay Locked Loop). These 59 • Area : 23mm²

DLLs give all the precision of the moment of sampling. On • Supply voltage : 3.3V ; Power : 800mW

the first version of the asic, jitter measurements were made • Input span : 2Vpp

- 146 -















50MHz / 12bits





Gestion USB

Carte d'acquisition commandée par un module USB





Fig. 1 : Functional diagram of the test bench of the asic


General & technical departments

• Input bandwidth : 350MHz

• Expected S/N ratio: 72dB

• Programmable time bases (in GSPS) : 2, 1, 0.5,

0.2, 0.1

• 1239 memory cells (matrix of 21x59 cells)

• Memory depth : from 619.5ns to 12.39µs (in

function of the selected time base)

• Read time (Sending of all the analog samples to

the ADC) : 25µs

Asic status

All the analog part of this ASIC was designed, simulated,

optimized and drawing by the SEP.

All the digital part allowing the control of the analog

pipeline was designed by the SEP and the layout (drawing)

was made at Strasbourg thanks to the help of A. Himmi

(Laboratory IReS/IN2P3).

The first version of the asic was sent to the AMS foundry at

the beginning of December 2004, and we received 25 chips

in the middle of march 2005.

The design and the realization of the asic test bench was

performed in parallel with the foundry of the asic.

For few weeks, the SEP has tested the asic (cf. Fig.2), and

for a first prototype, good results appeared. Below, we can

see some sampling results (made by MAR):

Fig. 3 : Sinusoidal signal with a 20MHz frequency and an

amplitude 800mVpp

Some mistakes appeared during the test. Thus, some

correction of the layout will be done, and a new version of

the asic will be sent to the AMS foundry in the first quarter

of 2006. So, the new version will be tested in mid-2006.

It is important to note that the first version of the asic

MAR works and thus, we will use it in a demonstration

board for AZ4π experiment despite its imperfections.

Future objective

The final goal is to realize a fast acquisition board :










Fast Analog




Sampling Board

Acquisition controller


Data storage


Communication controller





Fig. 5: Acquisition board for AZ4π

GBit Link to





This board will meet the following characteristics :

‣ Compactness (a few cm²) for the integration close to

the detectors (a few thousands channels must be


‣ low thermal dissipation.

‣ Modularity.

‣ One energy channel.

‣ One channel for the process of the current signal

(shape analysis).

So, the first objective is to correct the layout for the second

version of MAR (mid-2006).

The second objective is to realize a fast acquisition system

for the AZ4π R&D program, with the collaboration of LPC

Caen and INFN Florence. This system will integrate, of

course, the asic "MAR", and will be able to do recognitions

of the current signals coming from the preamplifier PACI.

For the first version of this system, we will use the first

version of the asic MAR. The first version of this board will

be available in the beginning of 2006.

Fig. 4 : Sinusoidal signal with a 100MHz frequency and an

amplitude 650mVpp

- 147 -

General & technical department

The Frrontt End Electtrroni

ics off tthe AGATA dettecttorr

IPNO Participation : P. Edelbruck, X. Grave, C. Huss, C. Oziol, S. Royer.

Collaboration : CCLRC, CSNSM, INFN, IReS.

L’électronique de Front-End du détecteur AGATA

AGATA est un spectromètre gamma destiné aux expériences de physique des noyaux exotiques. Il comprend 180

cristaux de germanium de gros volume fonctionnant à basse température. Chaque cristal est segmenté en 36

sections dont les électrodes sont lues par des préamplificateurs à faible bruit embarqués. Ce détecteur apportera,

par rapport à ses prédécesseurs une grande amélioration en efficacité (zones mortes réduites) et en résolution. Il

bénéficiera, au niveau de son électronique de deux innovations techniques majeures : un traitement entièrement

numérique des signaux, associé à une méthode de localisation des interactions basée sur l’analyse des impulsions

de collection de charge. Chacune des 7000 voies d’électronique sera munie d’un convertisseur Analogique-

Numérique à grande vitesse et grande résolution (Flash ADC) associé à une électronique d’acquisition fortement

intégrée. C’est cette électronique qui est en cours de développement à l’IPN, en collaboration étroite avec le

CSNSM voisin. Ce dernier fournira les cartes de traitement de premier niveau (1250 unités) et l’IPN l’infrastructure

bâtie sur le nouveau standard de télécommunication ATCA (360 cartes portées par 30 châssis).

AGATA is a gamma ray detector aimed to high resolution γ

-ray spectroscopy with exotic beams. Despite its large size,

it is designed to be “portable” and will be used in several

nuclear physics facilities in Europe. The detector is made of

180 crystals of high purity germanium. Each crystal is

segmented into 36 volumes, each of which bearing one

electrode, also called segment, read by a high resolution

preamplifier. The detector will provide significant

improvements over its predecessors in terms of efficiency

(reduced dead zones) and resolution. It will benefit from

two major technical innovations: all signal processing will

be entirely digital and new localisation algorithms will be

performed on the charge signals, allowing for

unprecedented spatial precision. To achieve these goals,

each of the 7000 channels will be read out by a high speed

analog to digital converter associated to a strongly

integrated digital electronics. This electronics is currently

being developed between IPN and the neighbour lab

CSNSM. The later is providing the first level local level

mezzanine boards (1250 units) while IPN is designing the

infrastructure, based on the new ATCA telecom standard

(360 boards located in 30 crates).

Computing Architecture. This is a new hardware standard

originally designed for telecommunication systems,

featuring very high bandwidth (potentially hundreds of

Gbyte/s). One crate can accommodate up to 16 large

boards, with a form factor well suited to carry the projected

pre-processing modules. Communication between the

chassis and the external world is performed by one or two

switching boards locally connected to the carriers through

high speed serial links located on the backplane. One single

link offers up to 10 Gbit/s of data rate. The actual

communication protocol is not defined by the standard and

remains open for a future choice. The first demonstrator

will use the well known Gigabit Ethernet standard while the

final version will use PCI-express or Infiniband offering

even more bandwidth.




3 X 2 Carriers =

1 cluster



11 9 7 5 3



3 X 2 Carriers =

1 cluster


6 8 10 12 14 16







1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

The 36 fold segmented germanium crystal

The ATCA standard

The AGATA throughput is currently estimated to 380

Mbyte/s per crystal i.e. 2.2 Gbyte/s for the 6 crystal filling

in one crate. A breakthrough was really required to cope

with such a data rate. The solution was found with ATCA.

The acronym stands for Advanced Telecommunications

- 148 -



One chassis bearing the electronics of 6 crystals

System architecture

The signals issued by the crystals are first digitized in the

vicinity of the detectors by an ensemble of ADC (14 bit -

100 Msample/s) developed by IReS in Strasbourg. The high

speed digital stream is transported to the local level

General & technical department

processing electronics through optical fibres at the rate of 2

Gbit/s. One set of fibres is handling 6 electrodes, 6 sets

being required for one crystal, plus one for the central

contact. Each fibre feeds one mezzanine card where the

digital stream is rebuilt for processing using high speed

deserializers (SERDES). Field Programmable Gate Arrays

(FPGA) perform in real time the calculation of the energy

of physical events (digital shaping) and the recording of the

signal shape, just like a digital oscilloscope. Another type

of mezzanine board (Global Trigger System) designed in

Padova (INFN) provides an accurate clock to the whole

system. It also delivers the “date” of all physical events

with a resolution of 10 ns (Time Stamping).

1 crystal

6 Segments


6 Segments




6 Segments


6 Segments


6 Segments


6 Segments


















The electronics of one crystal







The pre-processing boards

The pre-processing boards are built around state of the art

FPGA of the Virtex-II pro family. Two chips are required

for six channels. Each chip bears the deserialsers, one

power-PC processor and several millions of programmable

logic gates performing all the digital processing in real

time. The boards communicate with the central control

system through Ethernet links taken over from the carrier


Data acquisition


TCLK port

Slow control




The carrier boards

JTAG connect.









32 bits 100Mhz


LSA connect.



CPU serial


Config CPU





FIFO Acquisition


FIFO Carrier






The carrier board

32 bits






32 bits

100ME Base

PHY Fabric
















PCI Express

ou GbE

I2C thermal

And power



3.3V 2.5V

1,2V 1.5V 1.8V

The role of the carrier boards is to provide an infrastructure

to the processing mezzanine cards. Each detector will

necessitate two carriers holding six segment mezzanines,

one central contact mezzanine and one GTS card. The first

facility offered by the carrier is of a mechanical nature. One

carrier card will house four mezzanines built in the

standard PMC form factor. The connexions to the detectors,

to the ADC system and to the central trigger will be

performed through the front panel with optic fibre

connectors. The carrier board will also generate the

voltages required by the various components. Up to 200 W

of power will be converted into 6 different low voltages

from the unique 48 V source provided by the ATCA


Two large FPGA will handle the data acquisition process

itself. Synchronisation signals will be received from the

GTS board and distributed to all mezzanines. Trigger

requests will be gathered from the central contact and sent

to GTS. Trigger commands will then be dispatched to all

cards. When the reading process is completed on each

mezzanine (energy calculation, signal storage etc.) the

carrier board will collect the data from all modules, build

the event package and send it to the central DAQ through

the backplane and the switch boards.

Last but not least, the carrier will handle all the “slow

control” issues, ranging from basic house keeping like

power and temperature management, software download, to

physics parameter handling and online calibration

procedures. As the total number of FPGA in the system

will be very high (several thousands), all possible

maintenance operation like updating the hardware codes

(VHDL) will be feasible from the remote central control

system without any manual intervention on the boards. All

slow control communication will be performed through

standard Ethernet links using the TCP/IP protocol, making

remote control versatile and portable.

Pulse shape analysis

The 30 ATCA chassis will communicate with a large

processor farm which will perform the in-line analysis of

all the channels in order to extract two important data :

- The geometrical location of the interaction within the

crystal. This information will permit a precise

correction of the Doppler Effect affecting the energy

measurement, leading to a resolution improvement of

an order of magnitude over existing detectors.

- In the case of a Compton cascade, determine the

position of each photon belonging to the event and

calculate the total energy as well as the angle of the

original photon.

The next future

Building and testing the electronics will take three steps :

one single detector will be equipped and tested mid 2006 in

Orsay. A demonstrator made of a large set of 15 detectors

will then be constructed and used for real physics

experiments in 2007. The complete detector with 180

crystals will be ready by 2010.

- 149 -

General & technical departments


ics fforr MUST2 ((MUrr à Sttrri ip))

IPNO Participation : J.-P. Baronick, D. Beaumel, P. Edelbruck, G. Guerin, P. Guilland, D. Lalande, L.

Lavergne, L. Leterrier, V. Le Ven, A. Mongaillard, D. Rougier, S. Royer, S. Tanguy, M. Vilmay, E. Wanlin

Collaboration : GANIL, CEA/DAPNIA.

MUST2 est un télescope ∆E-E de seconde génération constitué d’un détecteur Si à 256 pistes double face suivi de

deux détecteurs Si(Li) segmentés en 8 secteurs et de seize cristaux de CsI. Les détecteurs, l’électronique front end

et la mécanique ont été pris en charge par le service détecteurs de la DR, le SEP et le SRM. L’électronique front

end est réalisée autour d’un composant intégré full custom (MATE3), conçu en collaboration avec le CEA/DAPNIA.

Pour l’électronique d’acquisition, elle a été conçue par le GANIL en standard VXI taille C. Actuellement, la

production d’un ensemble de quatre télescopes est lancée et sera achevée en janvier 2006. Le reste de la

production sera réalisé courant 2006. Les premières résolutions en énergies obtenues avec le détecteur Si à strips

sont de l’ordre de 40keV avec une source alpha 3 pics et de 30keV au générateur d’impulsion.

MUST II is a charged particle detector of second generation

developed in collaboration with GANIL, CEA/DAPNIA

and IPN. Each telescope (Fig 1) consists of a double-sided

Silicon strips (Si strips) detector, followed by two Silicon

Lithium (Si(Li)) detectors and sixteen Caesium Iodide (CsI)

scintillators with photodiode read-out. The Si strips detector

has128 strips on each side and the expected energy and time

resolution are 50keV and 250ps for 5.48MeV alpha. Each

Si(Li) detector is divided into 8 segments with the 120keV

desired energy resolution. For the CsI, the requested energy

resolution is 5% for 5.48MeV alpha.

All mechanics has been designed by SRM. In particular,

this mechanics is composed of the cooling system allowing

to drain the heat of electronic devices of outside the vacuum

chamber in order to hold a constant low temperature.

Si (Li)

Si (Strips)



Front end electronics

The front end electronics, realized by SEP, is located close

to the rear of each telescope and consists of two electronic

boards called MUFEEX3 (MUst Front End Electronics) and

MUFEEY3. The links between Si strips detectors and

electronic boards are made via Kapton flexible circuits.

Above, the top and bottom views of the MUFEEX3 board

processing 128 signals from the junction side of Si strips

detector, as well as the 16 channels of the Si(Li) detectors.

MUFEEX3 and MUFEEY3 boards are nearly the same.

Apart from MUFEEY3 which processes 128 signals from

the ohmic side of Si strips detector and 16 channels from


Each MUFEE bears 9 MATE3 ASICs (Application Specific

Integrated Circuits), each processing 16 channels in energy

and time. These energy and time information are carried on

2 analogue lines per board, read in current differential mode

through twisted pair to the external VXI crate. The MATE3

are connected in daisy chain and read one after the other.

The readout time for 544 information is 80µs.

In order to have a good immunity against the

electromagnetic perturbations, all readout signals are

transmitted in LVDS (Low Voltage Differential Signal).

The slow control, assured via the I²C industrial protocol,

allows in particular the configuration of the ASICs, the

temperature monitoring, the test signal injection, the

multiplexing of inspection channels, the board

identification and the memorization of experiment


On each MUFEE, one pulse generator drive each analogue

test input of each MATE3, which allows to check the good

functionality of all ASICs and to calibrate electronics


MATE3 (Must Asic for Time and Energy)

It has been realized in collaboration with the CEA/DAPNIA

from Saclay : SEP has developed the charge sensitive

preamplifier, the energy channel and the logic I2C

interface; CEA has taken responsibility for the timing

energy and other blocks explained later and for the final

assembly. The ASIC technology is the 0.8μm BICMOS

from AMS. MATE3 has 16 channels and delivers three

types of analogue information for each channel: time of

flight and energy loss of the detected particle and value of

DC leakage current. MATE3 also gives a trigger logic

signal corresponding to the cross over of an adjustable

threshold. The slow control of the ASIC is assured via the

I2C industrial protocol.

- 150 -

General & technical departments


The block diagram of one MATE channel is shown














Filtre & Ampli

Filtre &





+ discri - TAC

resetCSA seuils

requêtei stop

DAC 8 bits

Requete j





One channel consists in three main blocks : A charge

sensitive preamplifier, the energy block, and the time and

decision block.

MATE3 must be able to accept current signals coming not

only from both sides of the Si strip detector, but also from

SiLi and CsI detectors. This means that each channel can

process both signal polarities, from the charge sensitive

preamplifier to the energy and time blocks. Furthermore,

the charge sensitive preamplifier gain and the filter peaking

time are programmable to suit various kind of detectors and


Charge sensitive preamplifier

The architecture is a single ended folded cascade amplifier,

bipolar, using MOS and bipolar transistors. The input

transistor is a wide PMOS of 8500μm/1.2μm

(gm=28.4mS). The rise time of the preamplifier is 10ns.

A set of four integration capacitors programmable via two

slow control bits is used to match the desired gain

according to the selected detector.

The maximum energies to be accepted by the charge

sensitive preamplifier and energy block are +/-45MeV,

225MeV and 200MeV for the Si strips, SiLi and CsI

detectors respectively.

Energy channel

This block is composed of a shaper and a track and hold.

The shaper consists of a CR-RC filter, with respectively 1

and 3μs of peaking time, selectable by slow control, for the

Si strips and SiLi/CsI detectors.

Then, the amplitude of the signal is memorized via a track

and hold stage on the rise time of the HOLD signal coming

from MUVI. In read out mode, this memorized signal is

sent to a Voltage to Current Converter (VIC) whose transfer

gain is +/-2mA/V.

Timing and decision channel

This channel has two main objectives : determine quickly

whether the channel has triggered or not and measure the

time of flight of the particle.

The first section is a fast CR 2 -RC filter with a peaking time

of 22ns; it has a differential structure, thus providing

immunity against parasitic coupling and reducing jitter to

achieve a good time resolution. The differential outputs of

this shaper, then, pass through a leading edge discriminator,





in which the threshold voltage is set by an internal 8 bits

programmable DAC.

The discriminator output gives the start signal to the time to

amplitude converter (TAC) as well as the « REQUETE »

signal which is ‘or wired’ with the other fifteen channels of

MATE3. The intrinsic time resolution of the TAC is 18ps

FWHM. The TAC is stopped by an external signal “STOP”

coming from MUVI.

In read out mode, the time information is sent to a Voltage

to Current Converter.

The TAC has two programmable time ranges: 0ns/300ns

and 0ns/600ns.

Power consumption, layout and package

The power consumption of the chip is 447mW. The layout

is shown hereafter; the area is 41mm2

(6.438*6mm.368mm). MATE is packaged in a ceramic 64

pins TQFP64L.



Complete telescope system

The GANIL developed a VXI-C standard board, called

MUVI (MUst in VXI), assuring the slow control, data

coding, digital processing and data memorization for four

telescopes. The management of trigger signals is performed

by the GMT module.

The communication between MUFEE and MUVI boards is

carried in the eight meters transmission line.

The ensemble of front end electronics is supplied by several

CAEN power supply modules located in SY1527 system.

Châssis VXI

MUVI (VXI taille C)







Interface VXI

Mise en forme

4 bus analog

& codage

Signaux cont

Slow control

Bus I2C

Trigger local

Trigger externe


1 bus analog

bus I2C 1 bus analog

signaux cont.





128 strips en Y

16 pads

128 strips en X


1 bus analog

signaux cont. bus I2C 1 bus analog

Détecteur Si strips

Détecteur Si(Li)

16 pads

Détecteur CsI


- 151 -

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