A burst of π+ mesons (or pions) travels down an evacuated beam tube at Fermilab moving at 0.89c
with respect to the laboratory.
a) Compute γ for this group of pions.
b) Pions are very short-lived particles. The proper mean lifetime of pions is 2.6 x 10-8 s. What mean
lifetime is measured in the lab?
c) If the burst contained 50,000 pions, how many remain after the group has traveled 50 m down the
beam tube?
d) What would be the answer to c ignoring time dilation?

Question

A burst of π+ mesons (or pions) travels down an evacuated beam tube at Fermilab moving at 0.89c
with respect to the laboratory.
a) Compute γ for this group of pions.
b) Pions are very short-lived particles. The proper mean lifetime of pions is 2.6 x 10-8 s. What mean
lifetime is measured in the lab?
c) If the burst contained 50,000 pions, how many remain after the group has traveled 50 m down the
beam tube?
d) What would be the answer to c ignoring time dilation?

fwizbang · Answer

you know v, how is gamma related to v?