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particle flux unit

1

A unit used in measures of subatomic particles hitting spacecraft. One particle flux unit equals 1 particle per square centimeter of sensor area per second per steradian. The abbreviations PFU, pfu and p.f.u. are all encountered, but the most authoritative sources prefer “pfu”.

Some include the energy of the particles in the definition, namely, 1 pfu = 1 particle per square centimeter·second·steradian·kiloelectronvolt.

2

An informal unit used by geologists in the study of settling particles in the ocean. Currently, 1 particle flux unit is 1 milligram per square meter per day.

Susumu Honjo.
Chapter 7. Fluxes of Particles to the Interior of the Open Oceans.
in
Particle Flux in the Ocean.
V. Ittekkot, P. Schäfer, S. Honjo and P. J. Depetris. eds.
John Wiley and Sons, 1996.