1. The LHCb Calorimeter system
Y~7m
X~8.5m
Z~2.7m
HCAL
ECAL
PS/SPD
mrad
mrad
VELO Vertex Locator
MAGNET
Calorimeters Energy measurement PID: e,, 0
Muon Stations
RICH 1 & 2 PID: K vs. π
Trackers TT+IT+OT Momentum measurement
The LHCb calorimeter system covers the area of ~7x8.5 m2. It has classical structure with an electromagnetic (ECAL) and hadronic (HCAL) calorimeters. The ECAL is preceded by the Scintillating Pad detector (SPD) and Pre-Shower (PS) – two planes of scintillating pads, with 15 mm thick lead converter plane between them.
The calorimeter system is intended to provide:
L0 trigger on high pT particles (4 μs for decision);
energy measurement and particle identification for hadrons, electrons and photons.
Its data are used in important physics analyses:
radiative decays of B-mesons: BdK*γ, BSφ γ, …;
decays with π0/η: Bd,s J/ψη, J/ψη’, …;
decays with electrons: BdK*e+e-
In all the four calorimeter subsystems the light signal produced in scintillator is captured by WLS fibers and read out by photomultipliers.
First years of running for the LHCb Calorimeter system and preparation for Run II

2. The Calorimeter system subdetectors
SPD PS
Lead
beam
PMT
WLS
fibers
light guide
scintillators
CW base
PMT
MAPMT
SPD and PS:15 mm thick scintillator tiles with embedded WLS fibers
Light readout: 64-channel HAMAMATSU multi-anode PMT R M64MOD
Size ~(7.7 x 6.3) m2, 2x6016 tiles
3 zones: Inner (cell size 4x4 cm2), Middle (6x6 cm2) and Outer (12x12 cm2)
Tilecal technology (originally developed for ATLAS)
6 tile rows, ~5.6 λI.
2 zones: Inner (cells 13x13 cm2), Outer (26x26 cm2).
Total of 1488 cells, ~(8.3 x 6.7) m2.
Embedded radioactive source 137Cs calibration system
Shashlik technology
3312 modules 12x12 cm2, 25X0
Light readout: HAMAMATSU PMT R
3 zones and 3 module types: Inner (9 cells per module), Middle (4), Outer (1).
Total of 6016 cells, (7.7 x 6.3) m2.
First years of running for the LHCb Calorimeter system and preparation for Run II

3. The Calorimeter system performance
Some ageing of CALO system is present, accounted for by frequent recalibrations
Since the beginning of the LHC operation, the LHCb calorimeter system runs successfully and meets its design parameters. Shown here are plots of reconstruction of several B decay channels, where calorimeter performance is crucial: BdK*γ; Bsφγ; BsJ/ψ η, BsJ/ψ η’.
B0 → K*γ
5279±93 ev
BS → φγ
691±36 ev
ECAL ageing, seen as variation of π0 reconstructed mass in time.
J/ψ → µ+µ-
η‘ → π+π-η(γγ)
J/ψ → µ+µ-
η → π+ π- π0
HCAL
Evidence of radiation ageing of WLS fiber /scintillator in HCAL central cells, per each tile row. From 137Cs scans.
First years of running for the LHCb Calorimeter system and preparation for Run II