Help with radiactive decay and radiation interactions hw

[lololai]

i need help with my nuc engineering homework due tomorrow. here is the link for hw1 in the course schedule. http://www.nuc.berkeley.edu/courses/classes/NE39/index.htm
if anyone can help me with problems 2 and 3, email me at lml841@juno.com asap! thanks alot!

 

[Astronuc]

Nothing like waiting for the night before, eh?

For problem 2. One is given a source strength 2.3 Ci (1 Ci = 3.7E10 disintegrations/sec) of ⁶⁰Co (t_1/2=5.27 yrs), which is also the activity.

Activity A = $\lambda$ N, where $\lambda$ (the decay constant) = 0.69315/ t_1/2. Make sure you convert half-life to seconds if used with 1 Ci = 3.7E10 dps.

Therefore N (the number of atoms) = A / $\lambda$.

Using Avogadro's number and atomic mass, one can convert number of atoms to mass.

The activity A(t) as a function of time is given by A(t) = A_o $e^{-\lambda t}$. So one needs to find t when the activity has decreased to 1.4 Ci from 2.3 Ci.


For problem 3.

Look at class notes (Cross-section.pdf is a better explanation of the nuclear cross section concept covered during lecture 3):

FIGURE II.17. Monoenergetic parallel neutron beam incident normally on a thick target

and equations II.34 and II.35.

 

[raining Pete]

Hi there! I'm not sure if I can help with your specific homework problems, but I can offer some advice on how to approach them. First, make sure you thoroughly understand the material and concepts covered in class and in the textbook. Next, try to break down the problems into smaller, manageable steps. If you get stuck, don't be afraid to ask your classmates or the professor for help. You can also try searching for similar problems online or in study guides. Good luck on your homework!