Status of Atlas Tile Calorimeter and Study of Muon

InteractionsL. Price for TileCal community

Short Overview of the TileCal Projectmechanicsinstrumentationelectronics

TileCal and muonsmuons for calibration of the TileCalmeasurement of muon energy losses

ATLAS hadron calorimeter TileCalTileCal community = 24 institutions

TileCal within the Atlas detector:- measures jets energies and directions- provides ATLAS with LVL1 trigger signals

TileCal - Barrel and 2 Extended barrels, each cylinder consists of 64 modules

Principle of the TileCal

Photomultiplier

Plastic scintillatorinside steel absorberstructure

WLS fiber

Principle of TileCal is a measurement of scintillation light produced by charged particles in plastic scintillator.

TileCal modules production:

BARREL - 65% of modules finished in JINR Dubna

EB A - 50% modules finished in US EB C - 73% modules finished in Spain

564 cm

292 cm

Modularity of the Tile Calorimeter

3 cylinders - barrel and two extended barrels

Each cylinder consists of 64 modules (+1 spare)

SUBMODULES Total number of submodules needed:65x19 + 2x65x9 = 1235+1170 = 240590% is done and the production of submodules will finish in the spring of 2002.

1. Stacking

2. Welding

3. Painting

Barrel = 19 submodules,Extended barrel = 9 submodules + special ITC submodules - more than 50% are finished

Monitor of production quality in all 9 plants

Scintillator tiles (100% are produced)wrapped in Tyvek sleeves

profiles with inserted fibres (65%)

Instrumentation of modulesin 4 different plants

Instrumentation of modules:

In total more than 50%modules are ready for calibration and preassembly

Cell to cell uniformity 6-7% < 10% (target value)

Cells are formed by making fibres bundles

Cylinder preassembly will start in April 2002 in building 185 at CERN

- EB C will be assembled first- Barrel- EB A

Installation in the pit is foreseen to start in Dec 2003 with the barrel

180 cm

564 cm

Electronics

Main goal is to start serial production of drawers containing electronics

PMT blocks PMT’s

Photomultipliers

Quantity: barrel : 45 PMTs/superdrawer * 65*2 = 5850 PMTs Ext. barrel : 32 PMTs/superdrawer * 65*2 = 4160 PMTs; total : =10010 PMTs

PMT‘s : 45% of tubes delivered and good quality proved by tests in 6 different labs.

PMT test bench

8 barrel modules and 16 extended barrel modules will be calibrated using particles.

Calibration of modules will be done with Cs radioactive source for all modules

90° Incidence

20° Incidence

H8 Table Setup

2001 Tiles Testbeam Program

Response to 180 GeV muons, pions, electrons

180 GeV e at 90°

Summary

180 GeV e at 90°

Summary

Target Value

1.2 pC/GeV/Cell

Target Value

1.2 pC/GeV/Cell

Interactions of different particles inside the TileCal

electron

pion

muon 1/50

1/500

Calibration of the TileCal using muons

•Cells of the first longitudinal sampling are calibrated with electrons of 20 to 300 GeV

•All calorimeter cells are calibrated relatively each to other using Cs radioactive source. •Precise description of TileCal response to muons (ATL-TILECAL-97-114). The most probable value of the muon signal can be used for the calibration.

Muon signal can be used also for in situ calibration.

Calorimeter light yield measured with muons

L

R

L + R

σ (L - R)2

muon

slope ~ 1/ Npe

Signal in each TileCal cell is read out from two sides L and R. Differences of signals are caused by photoelectron statistics

Typical values are 50-60 photoelectrons per 1 GeV of energy deposited in cell.

Muon energy losses in iron

Muon s with 150, 180 GeVare close to the critical energy

Mechanisms of muon energy losses

•Knock-on electrons •Bremsstrahlung•e+e- pair•Photonuclear interactions

Physics motivation for muon energy loss measurements

•Muon traverses more than 100 radiation lengths of dense calorimeter material before being measured by the muon system.

•There is a probability of 60 % that in H-> 4 μ at least one muon loses more than 10% of its energy (P~.002/rl)

•It is therefore essential to measure muon energy losses in the calorimeter

•Also the highest muon energy losses are dominated by bremsstrahlung and momentum transfer to nucleus is much higher than for electron bremsstrahlung. Consequently nuclear form factor should be taken into account.

•Nuclear form factor corrections were not known experimentally and different theoretical predictions exist.

•Photonuclear interactions of high energy muons at low momentum transfers are also poorly known experimentally and theoretical predictions implemented in different MC codes vary by an order of magnitude.

Measured differential probability of muon energy losses in TileCal prototypes

Published in Z. Phys. C 73 (1997) 455.

Theory without and with the nuclear formfactor correction to bremsstrahlung

Detailed measurements with the TileCal Module 0

μ

Nuclear form factor correction to muon bremsstrahlungEur. Phys. J. C 20 (2001) 3, 487-495

Atomic radius a times the minimal momentum transfer to nucleus δ

Unscreened nucleusScreened nucleus

(Published calculations give 0.5 to 1.5)

Measurement of muon photonuclear interactions

Top modules

Coordinate z

Coordinate z

Photonuclear int. Background

Central module

Bottom modules

muon

Photonuclear interactions: μ+A —>μ+ hadrons

Differential cross section of muon photonuclear interactions

(preliminary results)

Theory[C.19] Bezrukov, Bugaev,Sov. J. Nucl. Phys. 33 (1981) 635.

H1, ZEUS

Normalization is proportional to σ(γN)

σ(γN)

E lab

Our measurement

Summary

•Production of instrumented TileCal modules has passed 50% point and is progressing well.

•Production of superdrawers with electronics has started, first production modules have been calibrated at the beam and serial production will continue in the autumn after beam tests.

•Detailed studies of muon signal have been done with the TileCal module 0. Different mechanisms of muon energy losses has been studied, nuclear form factor correction to muon bremsstrahlung has been measured.

•Preliminary results about muon photonuclear interactions in iron have been presented.