physics

High Luminosity Large Hadron Collider

High Luminosity Large Hadron Collider is a physics topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand High Luminosity Large Hadron Collider rather than just read about it. In short: The High Luminosity Large Hadron Collider (HL-LHC; formerly referred to as HiLumi LHC, Super LHC, and SLHC) is an upgrade to the Large Hadron Collider, operated by the European Organization for Nuclear Research (CERN), located at the French-Swiss border near Geneva. From 2011 to 2020, the project was led by Lucio Rossi.

Key takeaways

High Luminosity Large Hadron Collider belongs to physics; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect High Luminosity Large Hadron Collider to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of High Luminosity Large Hadron Collider from memory before moving on to harder problems.

Reference excerpt

The High Luminosity Large Hadron Collider (HL-LHC; formerly referred to as HiLumi LHC, Super LHC, and SLHC) is an upgrade to the Large Hadron Collider, operated by the European Organization for Nuclear Research (CERN), located at the French-Swiss border near Geneva. From 2011 to 2020, the project was led by Lucio Rossi. In 2020, the lead role was taken up by Oliver Brüning. The upgrade started as a design study in 2010, for which a European Framework Program 7 grant was allocated in 2011, with goal of boosting the accelerator's potential for new discoveries in physics. The design study was approved by the CERN Council in 2016 through which HL-LHC became a full-fledged CERN project. The upgrade work is currently in progress and physics experiments are expected to start taking data at the earliest in 2030. The HL-LHC project will deliver proton–proton collisions at 14 TeV with an integrated luminosity of 3 ab−1 for both ATLAS and CMS experiments, 50 fb−1 for LHCb, and 5 fb−1 for ALICE. In the heavy-ion sector, the integrated luminosities of 13 nb−1 and 50 nb−1 will be delivered for lead–lead and proton–lead collisions, respectively. The unit inverse femtobarn (fb−1) measures the time-integrated luminosity in terms of the number of collisions per femtobarn of the target's cross-section. The increase in the integrated luminosity for the aforementioned major LHC experiments will provide a better chance to see rare processes and improving statistically marginal measurements.

Introduction

Many different paths exist for upgrading colliders. A collection of different designs of the high luminosity interaction regions is being maintained by the European Organization for Nuclear Research (CERN). A workshop was held in 2006 to establish the most promising options. Increasing LHC luminosity involves reduction of the beam size at the collision point, and either the reduction of bunch length and spacing, or significant increase in bunch length and population. The maximum instantaneous luminosity increase of the existing nominal LHC luminosity (1×1034 cm−2⋅s−1) is about a factor of 4 higher than the LHC's performance at its peak luminosity of 2×1034 cm−2⋅s−1, unfortunately well below the LHC upgrade project's initial ambition of a factor of 10. However, at the LUMI'06 workshop, several suggestions were proposed that would boost the LHC peak luminosity by a factor of 10 beyond nominal towards 1×1035 cm−2⋅s−1. The peak luminosity at LHC was limited due to the cooling capacity of its triplet magnets and secondly due to the detector limits. The resultant higher event rate posed challenges for the particle detectors located in the collision areas. Through the ongoing upgrades, HL-LHC's peak luminosity is expected to be 5×1034 cm−2⋅s−1 and would most likely be pushed to 7.5×1034 cm−2⋅s−1.

Physics goals The HL-LHC upgrade being applicable to almost all major LHC experiments has a wide range of physics goals. Increasing the number of collisions per bunch crossing to 140, each time a proton bunch meets at the center of the detectors, from the current number of 60, will open a number of new avenues for observing rare processes and particles. The boost in the integrated luminosity, or evidently the larger collision event datasets that would be accumulated through HL-LHC in case of all the LHC experiments, is the most significant aspect towards achieving the goals described below. The motivation for the construction of large underground infrastructure at HL-LHC therefore, is to have a high efficiency and highly reliable machine that can deliver the required integrated luminosity. Major goals of HL-LHC thus belong to the following five categories; improved Standard Model measurements, searches for beyond the Standard Model (BSM) physics, flavor physics of heavy quarks and leptons, studies of the properties of the Higgs boson, and the studies of QCD matter at high density and temperature.

Measurements of the Higgs boson and understanding its connection to the electroweak symmetry breaking remains the primary goal. In the domain of flavour physics; LHCb, ATLAS and CMS together will test the unitarity of the Cabibbo–Kobayashi–Maskawa matrix, while ATLAS and CMS will measure the properties of the top quark, the fermion with the largest known mass and largest Yukawa coupling. HL-LHC will also add to the knowledge of parton distribution functions (PDFs) by measuring several Standard Model processes with the jets, top quarks, photons and electroweak gauge bosons in their final state. The jet and photon production in the heavy ion collisions forms the basis of QCD perturbation theory probes, and HL-LHC will measure this at very high energy scales. Owing to these high energy collisions, there is also a possibility for HL-LHC to detect BSM phenomena such as baryogenesis, dark matter, answers to the flavour problem, neutrino masses and insights into the strong CP problem. The upgrades to the heavy-ion injectors are also in progress and would bring up even more opportunities to observe very rare phenomena and to search for BSM physics.

Project timeline

The HL-LHC project was initiated in 2010, and the following has been the timeline till 2020, followed by the tentative future stages.

2010: HL-LHC was established at CERN as a design study. 2011: The FP7 HL-LHC design study was approved and started. 2014: The first preliminary report on the design study was published. 2015: Budget and schedule along with technical design report was made available. 2016: CERN Council approved the HL-LHC project with its initial budget and schedule. Followed by which the hardware parts consisting of components and models were validated. Between 2018 and 2020: The prototypes were tested and final Technical Design report was published. The underground excavation work was also carried out. Although the civil engineering work and prototyping process would continue till the end of 2022.

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with High Luminosity Large Hadron Collider

Start with the simplest possible case. Write down what High Luminosity Large Hadron Collider claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In physics, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to High Luminosity Large Hadron Collider before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about High Luminosity Large Hadron Collider ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of High Luminosity Large Hadron Collider

In research: High Luminosity Large Hadron Collider appears in physics research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses High Luminosity Large Hadron Collider in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: High Luminosity Large Hadron Collider is common in secondary-school and first-year university syllabi. It links to neighbouring topics CERN facilities, Large Hadron Collider, Particle physics facilities, so understanding it makes those chapters shorter.
In everyday life: Look for High Luminosity Large Hadron Collider outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study High Luminosity Large Hadron Collider in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what High Luminosity Large Hadron Collider means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain High Luminosity Large Hadron Collider out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is High Luminosity Large Hadron Collider in simple terms?

Why does High Luminosity Large Hadron Collider matter?

Because it connects several physics ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study High Luminosity Large Hadron Collider?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on High Luminosity Large Hadron Collider.