physics

NA31 experiment

NA31 experiment 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 NA31 experiment rather than just read about it. In short: NA31 is a CERN experiment which was proposed in 1982 as a measurement of |η00 /η+-|2 by the CERN-Edinburgh-Mainz-Pisa-Siegen collaboration. It took data between 1986 and 1989, using a proton beam from the SPS through the K4 neutral beam-line.

Key takeaways

NA31 experiment belongs to physics; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect NA31 experiment to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NA31 experiment from memory before moving on to harder problems.

Reference excerpt

NA31 is a CERN experiment which was proposed in 1982 as a measurement of |η00 /η+-|2 by the CERN-Edinburgh-Mainz-Pisa-Siegen collaboration. It took data between 1986 and 1989, using a proton beam from the SPS through the K4 neutral beam-line. Its aim was to experimentally prove direct CP-violation.

CP violation While charge symmetry and parity symmetry are both violated for any transformation under the weak interaction, the CP violation is known only to appear in particular phenomena - kaon and B-meson decays - under the weak interaction. CP-violation was first theoretically developed for the Standard Model by Kobayashi and Maskawa in 1973 when they introduced a third generation of quark (bottom and top) and thus extended the Cabibbo matrix to the 3x3 CKM matrix, parameterizing the couplings between quark-mass eigenstates and the charge weak gauge bosons. CP violation then appears through the presence of complex parameters in this matrix. Determined from the relative decay rates of short- and long-lived neutral kaons into two neutral and charged pions, respectively, the so-called ε'/ε ratio which expresses the relative strength of direct CP-violation was known to be small but expected to be different from zero in the Standard Model. The measurement of this small deviation from zero was the aim of NA31 in order to prove the existence of direct CP-violation in kaon decays under weak interaction.

Evolution of the experiment NA31 found the first evidence for direct CP violation in 1988 with a ratio deviating about three standards from zero. However, shortly after, another experiment – E731 at Fermilab – reported a measurement consistent with zero. A better precision was needed by both NA31 and Fermilab to find consistent results and thus to allow a final conclusion. A new generation of detectors were thus built, both at CERN (for what became the NA48 experiment) and at Fermilab (KTeV). Finally, in 1999, the two new experiments confirmed both direct CP violation in the decay of neutral kaons (CERN Courier September 1999 p32), a discovery which was later recognized by honours, as one of the most important discoveries made at CERN. In particular the 2005 European Physics Society High Energy and Particle Physics Prize was awarded jointly to the NA31 Collaboration and its spokesman Heinrich Wahl.

The detector

The detector was compounded by wire chambers combined with calorimetry in order to determine K0 parameters (e.g. energy, decay vertex). A great precision on these parameters is required to define well the phase space for all the decay modes which are to be compared. It consists of :

an evacuated decay region. proportional wires chambers to measure the charged pion direction. liquid argon calorimeter with a good energy and position resolution to measure the photons from the pion decay. a hadron calorimeter to measure the energy of the charged pions. a plane of scintillation counters serving as muon identifiers.

See also List of SPS experiments NA48 NA62

References

External links NA31 CERN experiment record on INSPIRE-HEP

Illustrations

Worked examples

Example 1 — a first encounter with NA31 experiment

Start with the simplest possible case. Write down what NA31 experiment 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 NA31 experiment 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 NA31 experiment 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 NA31 experiment

In research: NA31 experiment 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 NA31 experiment 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: NA31 experiment is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1980s in science, CERN experiments, Particle experiments, so understanding it makes those chapters shorter.
In everyday life: Look for NA31 experiment 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.

Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “NA31 experiment” →

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study NA31 experiment in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NA31 experiment 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 NA31 experiment out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NA31 experiment in simple terms?

Why does NA31 experiment 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 NA31 experiment?

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 NA31 experiment.