1 ALICE T0 detector W.H.Trzaska (on behalf of T0 Group) LHCC Comprehensive Review, March 2003.

1

ALICE T0 detectorALICE T0 detector

W.H.Trzaska

(on behalf of T0 Group)

LHCC Comprehensive Review, March 2003

W.H.T. LHCC Comprehensive Review, March

2003 2

Evolution of Evolution of T0T0 detector concept detector concept

Initial proposal (TP, MoU) one detector does it all (MCP) cost ~1.5 MCHF (Greece,

Russia)

Fall 2000 split of FMD into 3

sub.detectors: Si FMDSi FMD, V0V0 and T0T0 (cost ~200 kCHF)

Spring 2001 Choice of PMT-based T0

(worked-out by a Russian team)

Spring 2002 Finland commits 200 kCHF to T0

and joins the T0 collaboration


2003 3

T0 must work for all ions and for all energy T0 must work for all ions and for all energy densitiesdensities

central

minimum bias


2003 4

Main requirements:Precise timing (50 ps) also on-lineMain LVL0 triggerRough on-line vertex (1.5 cm)Beam – gas suppressionPre-trigger for TDREvent spacing 25 ns (pp)Provide backup for V0 and FMDOperates in the magnetic field (0.5 T)Huge dynamic range (almost 1:1000)


2003 5

T0 – the final configuration:T0 – the final configuration:Two arrays of 12 PMTs with quartz radiators

T0 Right ( + 0.7 m) T0 Left ( - 3.5 m)

Two shoe boxes of fast electronics inside the magnet (+5 m and –5 m)Few creates of electronics outside the magnetLaser calibration system also outside the magnet


2003 6

Output signals:

T0 = (tr+tl)/2+td

T0v = tr-tl (ON/OFF adjustable during run)T0-L, T0-R, CoincTime and energies (all 24 PMTs)3 levels of sum energy Low Medium High


2003 7

T0 LeftT0 Left & & T0 RightT0 Right arrays: arrays: T0 LeftT0 Left & & T0 RightT0 Right arrays: arrays:

T0L -5 < < -4.5

T0R 2.9 < < 3.3


2003 8

Mechanics – T0 Right


2003 9

T0 Left


2003 10

T0-Right 1:1 prototype:T0-Right 1:1 prototype: T0-Right 1:1 prototype:T0-Right 1:1 prototype:


2003 11

Front view:Front view:


2003 12

Back view:Back view:


2003 13

End-cups on the base side:


2003 14

Mounting of the optical fibre (0.4 mm)


2003 15

PiLaserPiLaser400 nmpulse width <40ps roughly 400mW optical peak out of the fibre


2003 16

Possible location of shoe boxes:

Box50 W

Box50 W

12 PMTfull current

<15 W

12 PMTfull current

<15 W


2003 17

Inside the shoe box:

Inside the shoe box:

Am

p1gain=1

Am

p2gain=22

Am

p3ga

in=1

Mul

tiple

xer

D1

D2

Comparetor

output

output

Am

pg

ain

=2

2

Delay R1

R2

Delay

Adder

Dis

cri

min

ato

r 0

Shaper

Comparator

Input

Output

Dual CFDUnit

Dual CFDUnit


2003 18

Characteristics of the Dual CFD Unit


2003 19

Pre-TDR timetable

Production completed by July 2005Fully assembled T0 Tests before shipment to CERN Oct.

2005 Shipment to CERN – November 2005 Final tests – December 2005 Installation in ALICE – March 2006


2003 20

Pre-TDR financing

200 kCHF from Finland Sufficient to cover the detector and

front-end electronics

Readout electronics and integration with DAQ Collaboration with TOF group Greek contribution


2003 21

Highlights of 2002:Highlights of 2002:

Completion of the first draft of TDR (100 pages!)Mechanical prototype of T0 RightFinal multiplicity resolution simulationsElectronic prototypes: Dual CFD Unit (2 prototypes) Mean timer Circuit for generating T0V signal

Choice of laser and the layout of the laser calibration system


2003 22

Still to be chosen:

Final choice of time discriminators(test run @ CERN in July 2003)

Final configuration of readout electronics, DAQ and trigger collaboration with TOF discussions with the Greek team


2003 23

Measured performance of CFDU (JYFL) prototypeMeasured performance of CFDU (JYFL) prototype

5.3 ps/ch

Time walk

-40-20

0204060

1 10 100 1000 10000

Input amplitude [mV]

ps

Time walk

-40-20

0204060

1 10 100 1000 10000

Input amplitude [mV]

ps

Jitter = 25 ps (fwhm)


2003 24

The third option:

CFD DELAY

ADC RAM

RAMlogA

DELAY

T0

TlogA


2003 25

Mean timer prototype

C

1 2 p F

In1

I o

1 5 m A

+V

ECL/NIMDriver

Fastcomparator

I o

1 5 m A

NIM/PECLDriver

In2FastSwitch

FastSwitch

Out

NIM/PECLDriver


2003 26

T0VDC

Fast digitiser for T0V signal

Range of coded time intervals ±2.5 nsDigitisation step 20 ps (for 8-bit)Dead time not more than 25 nsTAC + Flash ADC


2003 27

T0VDC performance

0

50

100

150

200

250

0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 5.00

Delay [ns] vs. channel number

Calibration spectrum


2003 28

Cables and connection from L3

HV cables 2 x 12

Coaxial cables Thresholds 2 x 12 Bunch crossing 2 x 1 Time individual 2 x 12 Output Amplitudes 2 x 12 TRD wake up 2 x 4 T0 right/left 2 x 1

Optical fibre 2 x 12


2003 29

Counting room

Outside the Magnet (~5 m)

Inside the Magnet12 quartz counters

(T0 right)

Two ( left and right ) Constant Fraction Discriminator Units

1 ..................... 12

12 quartz counters(T0 left )

1 ..................... 12

BC

T0rightT0left

T0TRMs(T0 TDC Readout

Module)

Controlbus

T0signalDe-multiplexingcard LTM

(Local TriggerModule)

T0vertexT0signalT0multiplT0busy

1 ....................... 24

DDL

BC

Experimental area(~30 m)F

ast

char

ge

to t

ime

con

vert

or

(FQ

T)

RORC(Read-Out Receiver

Card)

LDC(Local Data

Concentrator)

T0left to TRD

T0right to TRD

De-

mu

ltip

lexi

ng

card

T0TRMs(T0 TDC

Readout Module )

DRM(Data Readout

Module)

BC

General, preliminary readoutscheme for T0:


2003 30

Layout and connections:

....

T0

TR

D

12 quartz counters(T0 right)

Two ( left and right ) Constant Fraction Discriminator Units

12 quartz counters(T0 left )

T0

AR

M

De

-mu

ltip

lex

ing

ca

rd

LTM

Am

plif

ire

s

DR

M

T0

AR

M

Ca

ma

c D

riv

er

VME Redaout Crate VME Local tTirgger Crate

LTU

TT

Cv

i

TT

Ce

x

Sin

gle

Bo

ard

Pro

cc

es

so

r

Camac Control Crate

Ge

ne

rato

r/L

as

er

cin

tro

ller

VD

L &

Ga

tec

on

tro

ller

Ca

ma

c c

rate

co

ntr

olle

r

T0

TR

M...


2003 31

Large change compared to the previous version of PYTHIA:

Efficiency of registration of p-p collisions

0 20 40 60 80 100 120 140 16050

55

60

65

70

75

80

85

90

95

100

Eff

icie

ncy

Multiplicity threshold

L R D

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1 ALICE T0 detector W.H.Trzaska (on behalf of T0 Group) LHCC Comprehensive Review, March 2003.

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