The subtle distinctions between these (and between other so-called modal verbs) are gradually disappearing, but they still matter to many readers and can be useful.

Lower case

mid-50s

mid-90s

mid-week

mid-season

But midday

Measure of radiation dose; symbol mSv

See sievert.

No hyphen.

An unstable subatomic particle of the same class as an electron (a lepton), but with a mass around 200 times greater. Muons make up much of the cosmic radiation reaching the Earth’s surface.

milliwatts

Use a capital letter when you are writing the names of places, and words relating to them:

Africa, African
China, Chinese
England, Englishman
France, He speaks French

See capital letters

Use "ndashes" – like these – to separate clauses in sentences. The HTML code to use is – Use hyphens elsewhere (compound adjectives, for example). 

The particle detector – housed in a custom-built cavern 100 metres below ground – is made up of concentric subdetectors. 

Plural: neutrinos.

A neutral subatomic particle with a mass close to zero and half-integral spin, which rarely reacts with normal matter. Three kinds of neutrinos are known, associated with the electron, muon, and tau particle.

Nobel prize in physics, Nobel prize in literature, Nobel peace prize etc.

See nobelprize.org for detailed information about Nobel laureates including biographies and full transcriptions of their acceptance speeches. 

It is a (persistent) myth that "none" has to take a singular verb: plural is acceptable and often sounds more natural, eg "none of the current squad are good enough to play in the Premiership", "none of the issues have been resolved"

Numbers

When applied to countable objects, spell out numbers below 10:

• There are four large detectors at the LHC.
• The LHC construction project had three phases.

For 10 and above, use digits. Numbers up to 9999 do not take a comma. Numbers with five digits take a comma every three digits. So it’s:

One, nine, 10, 100, 1001 and 9999, but 10,000 or 564,381 or 1,057,983.

Try to avoid putting numbers at the start of a sentence, but if it’s unavoidable, spell them out.

Not "okay"

No hyphen

CERN openlab has a lower case "o". See their website

The spontaneous process of one fundamental particle transforming into other fundamental particles. During this process, an fundamental particle becomes a different particle with less mass and an intermediate particle is created. For example, a W boson can decay into a tau and a neutrino. The intermediate particle then transforms into other particles. If the particles created are not stable - like the tau in this example - the decay process can continue.

Whenever you link to a PDF, make sure to put the link on the letters [PDF] inside square brackets. This is for people using the website on a mobile phone - PDFs can take a long time to load. 

Find out more about CERN in the general brochure [PDF]

Lower case. Not Petabyte, or worse, PetaByte

A unit of information equal to one thousand million million (10¹⁵) or, strictly, 250 bytes.

Almost overnight, companies are transitioning from storing gigabytes of data to managing terabytes, and even petabytes, of information.

See telephone numbers

Use only 2D pie charts, and label each slice with its corresponding percentage.

A rant about 3D pie charts

Never use 3D pie charts. They misrepresent data.

The important parameter of a pie chart is area. If the pie is represented in 3D, the foreshortening skews the area of each slice and the chart becomes misleading.

In the example below, the 1% slice is at the "back" of the chart – the perspective imposed makes that slice look smaller. Bringing this slice to the front would similarly skew the look of the chart, making the 1% slice look bigger.

Not pi-meson.

An ionized gas consisting of positive ions and free electrons in proportions resulting in more or less no overall electric charge, typically at low pressures (as in the upper atmosphere and in fluorescent lamps) or at very high temperatures (as in stars and nuclear fusion reactors).

The current passed through a column of plasma.

See quark-gluon plasma

Not policeman.