# physics

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Compute the average number of interactions per bunch crossing for a luminosity L=2.5E31 cms-1,if the total cross section is sigma =20mb and bunch crossing occur every T=4.What is the probability of having zero interactions in a bunch?

• physics -

What is a bunch crossing? Bunch of what?

What are mb units? Millbarnes?

cm/s is not a unit of luminosity

What is T? What are its units?

this is jibberish

• physics -

Trying to sort out the units.

20 mb = 20 millibarns (mbarn)?

the luminosity is presumably cm2 s^-1

because by definition

event rate = luminosity * cross section

Not sure of units of T ns?

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