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.


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


A cyclotron is an apparatus in which charged atomic and subatomic particles are accelerated by an alternating electric field while following an outward spiral or circular path in a magnetic field.

Perhaps the most important improvement has been the replacement of an electrical magnet with a series of permanent magnets to generate the cyclotron's magnetic field.

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