CALICE analogue HCAL

Analogue HCAL R&D for the ILC detector

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Introduction

An International Linear Collider ILC is proposed for the study of e⁺e^- interactions at very high energies where the production of multi-jet events with new heavy particles is expected.

: Figure 1: Active layers of the physics prototype

Optimal energy and mass resolution of all components of the final state will be achieved when the final state particle flow is reconstructed with highest possible detector granularity. Whereas all charged particles can be measured with sufficient precision in a large volume tracking system, the neutral particles have to be reconstructed and identified in a calorimeter system:
an electromagnetic calorimeter (ECAL) followed by a hadronic calorimeter (HCAL) with highest possible granularity.
The CALICE collaboration studies the performance of such calorimeters within a long, detailed R&D program for an ECAL and several options of high granular analogue and digital HCAL calorimeters with sensitive layers of gas or plastic scintillators. The Tile-HCAL subgroup has build a small prototype called MiniCal as well as a 1 m³ steel/scintillator sandwich sampling calorimeter called physics prototype for study series in various test beams. High granularity is achieved by 38 scintillator tile layers (90 x 90 cm²) along a depth of 5 λ. The mosaic of detector layers exhibits 3 x 3 cm² tiles in the center (100 tiles), surrounded by a large area covered with 6 x 6 cm² tiles and finally enclosed by a strip of 12 x 12 cm² tiles. MC studies show that such a tile pattern allows excellent longitudinal and lateral topological reconstruction of the cluster tree within the particle shower.
The 7608 tiles in total are read out individually by wavelength-shifter fibers which illuminate small photo-detectors on tile (SiPMs or APDs) insensitive to large magnetic fields. The SiPM signals are recorded in 16-bit ADCs.
In test beam studies the Tile-HCAL is headed by an ECAL (~1 λ) and followed by a tail catcher (~10 λ) to measure the shower leakage.
We are part of the european EUDET project.

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Instituts working on the Tile HCAL

Country	Institute	Contact person
Czech Rep.	IPASCR Prague	J. Cvach
France	LAL Orsay	C. De La Taille
Germany	DESY	F. Sefkow
Germany	Hamburg University	E. Garutti
Germany	Heidelberg University	H.-C. Schultz-Coulon
Germany	MPI Munich	F. Simon
Germany	Wuppertal University	C. Zeitnitz
Germany	Mainz University	V. Büscher
Norway	Bergen University	G. Eigner
Russia	JINR Dubna	I. Tiapkin
Russia	ITEP Moscow	M. Danilov
Russia	LPI Moscow	V. Kozlov
Russia	MEPhI Moscow	S. Somov
UK	Imperial College London	P. Dauncey
USA	Northern Illinois University	V. Zutshi
Europe	CERN	L. Linssen

The purpose of R&D

The goal of the ongoing R&D work is to demonstrate that particle flow measurements give the superior jet and heavy particle mass resolution expected. Measurements with different HCAL prototypes (scintillator tile, various tile sizes; RPC-gas; GEM-gas) will be performed and compared. For the Tile-HCAL option alternatively the analogue, semi-analogue (few bits) and digital (1-bit) use of the recorded information will be studied.

Charges of the test beam studies are to:

verify the MC predicted performance in the shower energy measurement of various particles in the momentum range from 1 - ~80 GeV/c,
study the energy resolution for all possible incidence angles,
study cluster/shower separation procedures as needed for the particle flow measurement,
study pattern recognition improvement by lateral staggering of layers,
study the energy- and angle measurement for jets with overlay of measured single particle shower patterns,
measure the e/pi response function of the HCAL,
measure the HCAL shower leakage for corrections in deposed energy,
study identification and tracking of penetrating cosmic and beam muon tracks, as required for online calibration of calorimeter cells,
check the identification of muon tracks within a hadronic cluster environment,
study calibration with MIP tracks within hadronic showers,
demonstrate stability, monitoring- and precise calibration capability of the HCAL prototype during year-long measurement periods,
optimize the cell level energy weighting procedure (compensation),
select, tune and improve the best MC simulation tools and
invent ⁄ select and improve the best cluster ⁄ shower reconstruction tools.

Further information

In case you got curios and want to learn more, also have a look at:

calorimetry - a brief desciption of the working principle
particle flow - the basic ideas and problems of this Ansatz
MiniCal - a small prototype to chose the read out technology
physics prototype - a proof of principle prototype as described above

For people working on this project

There are some additional information about:

testbeam - data taking at CERN and FNAL
elog - even more detailed run by run information
flc wiki - some hints for software users as well as developers
SiPM database - specifications for each SiPM
paper - written in our collaboration
meetings - talks on weekly, HCAL main, CALICE meetings and conferences
further links - on ILC related R&D, DESY, CALICE, ...