This lecture covers the fundamental equations that describe the decay of radionuclides. Basic equations and their utility are presented. Equations for mixtures, equilibrium, and branching of radionuclides are covered. Examples are provided for error evaluation from counts, activity determination, evaluation of half life, and lifetime of isotopes. Discussion of natural radiation and dating are given. Examples are provided for dating from 238U, 14C, and the Oklo reactor.
Finished listening to the 2 lectures and submitted the quiz. Hopefully I was thinking about questions 1 and 2 in the right direction. I tend to try and over complicate things. I am a little behind in the readings but hope to catch up before the exam is posted.
ReplyDeleteThanks for the comments. There were a number of questions on the quiz.
DeleteJust finished the quiz. I wasn't sure exactly how the first question was supposed to be done and I ended up making a spreadsheet to find the answer I chose. Everything else seemed straightforward and simple in terms of the lecture and the quiz.
ReplyDeletethanks for the comments.
DeleteFinished the quiz. I was confused with the first question until I realized it was giving me the relative standard deviation. Duh. So I rearranged a few equations and I think it worked.
ReplyDeletegreat approach. That is the correct way to work the question.
DeleteI have gone over the reading and looked at the videos but problem 1 is still being a royal pain. I feel like I'm doing half of it right and the other half is just me just randomly plugging numbers into equations.
ReplyDeletethanks for the comment. I will post something on questiob 1.
DeleteProblem 1 on the quiz is giving me quite a bit of trouble. I've been manipulating the equations around and I feel like I am getting to the right place, but the numbers don't agree with the choices listed and I'm not exactly sure what I am doing wrong.
ReplyDeletethanks for the comment. I will post a reply
DeleteI am also having trouble understanding how to do the first problem on the Quiz, but it is probably because this is my first time learning about decay statistics. The section of this lecture on branching in decay was pretty interesting. The part on cross sections being proportional to probability of a reaction is also a bit confusing to me but I'll work on it some more before the first test.
ReplyDeleteWe will discuss cross sections in more detail.
DeleteI submitted the quiz and like other have said, the first question was slightly confusing. After I went back and listened to the slide a few extra times, the question made sense.
ReplyDeleteGreat to hear about question 1.
DeleteJust finished watching the lecture and working through the quiz. The first problem was a little unclear at first but realizing it was asking more about a mathematical relationship helped me work through it. Excited to play around on the ERG nuclide program!
ReplyDeletethanks for the comment. There will be a question on quiz 1 using the ERG program.
DeleteQuestion 1 asks for the how long one needs to count a 5 Bq (5 decays/s) sample so the count error, (the relative error) is 3 %. Your detector has an efficiency of 2.5 %.
ReplyDeleteTo start the question one needs to remember that the relative error is the inverse of the standard deviation (see Lecture 3, part 1, page 9).
so
Error = 1/(standard deviation).
The standard deviation is the square root of the counts (M)
Standard deviation = M^0.5
So we get
0.03 = 1/M^0.5
M, the number of counts is equal to:
Activity*time*detector efficiency
Activity = 5 Bq, efficiency = 2.5 %
So this equation becomes
M = 5*time*0.025
M=0.125*time
We want to solve for time (in seconds)
0.03 = 1/M^0.5
0.03 = 1/(0.125*time)^0.5
(0.125*time)^0.5 = 1/0.03
(0.125*time)^0.5 = 33.333
0.125*time = 1111.1
time = 8888.9 seconds
1 hr = 3600 seconds
time = 2.47 hours.
So best answer from those present is 2.5 hours.