Central detectors -0.90.9
ALICE TPC (88 m3 in volume)
inner radius 90 cm
outer radius 250 cm
total number of channels 570,000.
ITS
improves momentum resolution (~ 5% at 100 GeV/c)
six cylindrical layers, radii ranging from 4 - 44 cm.
Silicon Pixel detectors (SPD)
Silicon Drift detectors (SDD)
double-sided micro-strip silicon detectors (SSD).
Four layers have analog read-out for PID
Time Of Flight detector (TOF)
multigap resistive plate chambers, intrinsic time resolution of the order of 50 ps
total surface of 140 m2; the total number of channels is 160,000.
discriminates between /K (K/p) up to pt~2 GeV/c (~3.5 GeV/c),
High-Momentum PID (HMPID)
seven modules, over 160,000 readout channels
HMPID /K (K/p) up to pt ~3 GeV/c (~5 GeV/c)
Transition Radiation Detector (TRD)
electron identification
six layers of radiator followed by Time Expansion Chambers
electron identification for pt  1 GeV/c
total surface is 800 m2
number of electronics channels is ~ one million
PHOS
prompt photons, 0's and 's are measured in PHOS
a single-arm, high-resolution electromagnetic calorimeter.
PbWO4 crystals
EMCal
Electromagnetic calorimetry0.7, =110o
moderate resolution Pb-scintillator sampling calorimeter
A calibration trigger on cosmic rays (ACORDE) is installed on top of the L3 magnet.
ALICE Muon Spectrometer
complete spectrum of heavy quark vector mesons (as well as the invariant mass
continuum) will be measured in the +- channel
The forward muon arm (2-9 degrees) consists of a complex arrangement of absorbers, a
large dipole magnet, and 14 stations of tracking and triggering chambers.
quarkonia states down to zero transverse momentum
consists of a front absorber a large dipole magnet (nominal field 0.7 T, field integral of 3
Tm) a high-granularity tracking system and a trigger system placed behind a passive muon filter
wall. The tracking system is based on cathode pad chambers. These are arranged in five stations
(each one made of two chambers): two of them are placed before, one inside and two after the
dipole and the total number of channels is about one million. Thanks to the high space resolution
(better than 100 m in the bending plane) and to the bending power of the magnet, an invariant
mass resolution as good as 70 MeV/c2 (100 MeV/c2) is achieved at the J/ () mass, allowing to
resolve all the heavy quark vector mesons. The aim of the trigger system is to select events
containing a pair of high-pt muons of opposite sign emitted in heavy quarkonia decays. The pt
selection is made by means of two trigger stations, each one consisting of two planes of singlegap Resistive Plate Chambers[11,12].
The ALICE setup is completed by several small detector systems at small angle
purpose of these detectors is to measure global event characteristics and to provide
interaction triggers.
Zero Degree Calorimeters [13,14] measure the energy carried by the spectator neutrons
and protons
placed at about 116 m from the Interaction Point.
Multiplicity Detector (PMD) and by the Forward Multiplicity Detector (FMD),
respectively. The former is a pre-shower gaseous detector; the latter consists of a mosaic of
silicon pads detector surrounding the beam pipe. The task of the T0 Cerenkov counter array is to
determine the event time with a precision better than 50 ns, while the one of the V0 scintillator
array is to provide a fast measurement of the event multiplicity.