
#1
May1409, 11:35 AM

P: 176

1. The problem statement, all variables and given/known data
Three proton decays per cubic kilometer of water per year are detected by an array of photomultipliers immersed in the sea. Find the mean lifetime of the proton. 2. Relevant equations t = 1 / lambda 3. The attempt at a solution How is it possible to work this out without knowing the halflife? 



#2
May1409, 11:39 AM

Sci Advisor
HW Helper
P: 8,961

How many protons are there in a km^3 of sea water
How many decay per year? So whats the decay rate? 



#3
May1409, 02:06 PM

P: 176

about 6 x 10^29 , but im not too sure if this is correct. the decay rate is 3 proton per km^3 per year but what equation do I need to work out the mean halflife? is it decay rate = (lambda)(N)e^(lambda)(t) ? 



#4
May1409, 03:39 PM

Sci Advisor
HW Helper
P: 8,961

Radioactivity.
It doesn't ask for a halflife it asks for an average lifetime.
If 3 in 6 x 10^29 decay per year  then the average time for a proton to decay is just 1/decay rate (from dimensions) 



#5
May1409, 06:29 PM

P: 176




Register to reply 
Related Discussions  
Radioactivity Help!  Advanced Physics Homework  3  
Radioactivity  Introductory Physics Homework  8  
forces are actually involved in radioactivity  High Energy, Nuclear, Particle Physics  23  
radioactivity  Introductory Physics Homework  1 