The High-Luminosity Large Hadron Collider (HL-LHC) project aims to crank up the performance of the LHC in order to increase the potential for discoveries after 2027. The objective is to increase luminosity by a factor of 10 beyond the LHC’s design value.
Luminosity is an important indicator of the performance of an accelerator: it is proportional to the number of collisions that occur in a given amount of time. The higher the luminosity, the more data the experiments can gather to allow them to observe rare processes.
The High-Luminosity LHC, which should be operational from the end of 2027, will allow physicists to study of known mechanisms in greater detail, such as the Higgs boson, and observe rare new phenomena that might reveal themselves. For example, the High-Luminosity LHC will produce at least 15 million Higgs bosons per year, compared to around three million from the LHC in 2017.
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Pixels
The Silicon Pixel detector immediately surrounds the interaction region of the proton-proton collisions. Its primary role is to detect the charged particles issued from the interactions, measure their directions and subsequently precisely determine the position of the primary interactions.
During HL-LHC running, more than 200 hard parton-parton interactions will occur at each bunch crossing. The new Pixel detector has been designed to cope with the large increase of detector occupancy and data rate. New radiation-hard technologies have been developed.
Strips
Consisting of 165 m2 of silicon sensors, the ITK Strip detector will be the largest tracker in ATLAS at the HL-LHC. The detector is designed to provide a fast and precise measurement of the trajectory and momentum of charged particles despite the busy environment expected in high-luminosity collisions. The detector is also designed to withstand 10 years of data taking in a high-radiation environment. US-ATLAS will contribute half of the barrel Strip detector.
Global Mechanics
The Global Mechanics structures are the primary integration supports for the Strip and Pixel subsystems of the Inner Tracker. The Outer Cylinder has a diameter of 2.1m and is 6m long. The Outer Cylinder allows the ITk to be assembled on the surface and lowered as a unit to be inserted into the Inner Warm Vessel of the ATLAS Argon Barrel. The Strip Barrel Shells and Pixel Support tube are supported by the Outer Cylinder and are designed to be stable at micron level during operation. The structures also perform as a faraday cage and gas enclosure for the
Liquid Argon (LAr)
The LAr calorimeter provides precision energy measurement of electromagnetic showers in the barrel and endcap regions, and energy of hadrons in the endcap and forward regions. It plays crucial roles for detecting electrons, photons and jets, and for measuring missing transverse energy in the detector system. The readout system both on and off detector, made of 180 thousand channels, will be replaced with more advanced analog and digital electronics for HL-LHC operation.
Tile
The "Tile" Calorimeter is the part of the calorimeter system that measures the energy of hadrons and other particles that are not fully measured in the electromagnetic calorimeter. Full measurement of the hadronic energy is essential for reconstructing the "jets" that are created by the decay of quarks and gluons emerging from the proton-proton collision. Tilecal consists of steel plates in which hadrons create a shower of particles, interspersed with plastc scintillators that emit light proportional to the shower energy.
Muon
A muon is a fundamental particle similar to electrons (same charge, same spin) but with a much larger mass. These particles are often found in the decay of some of the most exciting physics processes the ATLAS experiment is studying, such as those in Higgs physics and new physics beyond the standard model. The ATLAS muon spectrometer, made up of over 4,000 individual muon chambers, is over seven stories high and 150 feet long. During HL-LHC operation, the collision rate will be dramatically increased within the ATLAS detector. USATLAS is
TDAQ
The Trigger and Data Acquisition System will consist of a single-level hardware trigger that analyses calorimeter and muon detector information at 40 MHz within 10 μs latency. After the hardware-based trigger decision, the resulting full detector and trigger data will be read out at a rate of 1 MHz. An upgraded Event Filter system will provide high-level trigger functionality using commodity hardware, refining the trigger objects in order to achieve a maximum output rate of 10 kHz.