Preferable to "about".

Use the full word. Don't abbreviate to "approx.", or worse, the symbol  "~".

The luminosity of the LHC has increased by approximately 16% over the last two months.

Atomic Spectroscopy And Collisions Using Slow Antiprotons

category of member of the personnel

Actuarial and Technical Committee (CERN Pension Fund)

A Toroidal LHC Apparatus

Acronym never to be spelled out for any audience

Antihydrogen TRAP Experiments

Acronym doesn’t need spelling out for the CERN Courier

Use in the CERN Courier 

Symbol b.

A unit of area. A barn is 10⁻²⁸ m² (100 fm²), about the cross-sectional area of a uranium nucleus.

A barn expresses the cross-section of any scattering process, which relates to the probability of interaction between small particles.

Sample size at CERN is often expressed in femtobarns and luminosity is expressed in inverse femtobarns.

Adjective: baryonic

A subatomic particle, such as a nucleon or hyperon, that has a mass equal to or greater than that of a proton.

Two words. See beam line

every second year

bit/s, kbit/s, Mbit/s, Gbit/s

Brookhaven National Laboratory

Spell out in first use then use acronym for the CERN Courier

no italics

A subatomic particle, such as a photon, which has zero or integral spin and follows a statistical description given by SN Bose and Einstein.