1. The Hadron Calorimeter (HCAL)
HCAL Barrel
HCAL Endcap
Optical fibres carry the signals of particles detected by HCAL
HCAL Forward Calorimeter
The Hadron Calorimeter (HCAL) measures the energy of composite particles called hadrons, such as protons, neutrons, kaons and pions, which are made of quarks and gluons. In addition, it also indirectly measures the presence of non-interacting, uncharged particles such as neutrinos. With the exception of muons and neutrinos, the HCAL is designed to stop all other known particles produced in collisions inside CMS. HCAL consists of 70,000 tiles grouped into scintillator trays sandwiched between layers of brass and quartz fibres embedded in a steel matrix.
How was the HCAL built?
How does the HCAL work?
Image 2 – Achintya to to provide 1) 2)
Image 1: Achintya to explain how to change that image (violet lines should be square…)
Scintillators with optical fibres form megatiles used in the HCAL Barrel
HCAL Barrel is made up of 36 wedges each of which weighs as much as 6 elephants
Layers of dense absorbers (brass or steel) interleaved with plastic scintillators or quartz fibres are used to determine the energy of hadrons coming from the LHC’s collisions. The scintillating materials produce a signal proportional to the number of charged particles traversing them.
When a hadronic particle hits an absorber plate numerous secondary particles are created. These secondary particles flow through successive layers of absorber resulting in a cascade or “shower” of particles.
When this shower passes through layers of plastic scintillators a blue-violet light is emitted. Within each scintillator tile optical fibres, with a diameter of less than 1mm, absorb this light. The fibres then shift the blue-violet light into the green region of the spectrum, and clear optic cables carry the signal in the form of this green light. 3) 4)
Over a million World War II brass shell casements from the Russian Navy were repurposed into components for the HCAL Endcap
One HCAL Endcap disc during construction 5) 6)
Quartz fibres make up modules of the Forward Hadron Calorimeter
Hadron Forward Calorimeter was a first CMS piece lowered to the cavern
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