millibarn

millibarn

[′mil·ə‚bärn]
(nuclear physics)
A unit of cross section equal to one-thousandth of a barn. Abbreviated mb.
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References in periodicals archive ?
where [[sigma].sub.pp], [[sigma].sub.nn], and [[sigma].sub.np] is the proton- proton, neutron-neutron, and neutron-proton interaction cross section and it is expressed in millibarn (mb), [beta] = v/c, [E.sub.lab] is the incident kinetic energy of the nucleon in MeV in the laboratory frame of reference, and [rho] is the nuclear matter density in unit of [fm.sup.-3].
The prefix yocto- means 10 exp -24, and yoctosecond (unlike anything below a millibarn) has a good chance of being used.
It turns out that even a barn is rather large for expressing the area over which certain nuclear reactions occur, and physicists have felt it necessary to define an even smaller area, the millibarn: A unit of nuclear cross section equal to 1/1000 barn