Wednesday, September 10, 2014

CHEM 312 Fall 2014: Lecture 4 Alpha Decay

This lecture discusses alpha decay in radionuclides. Theories on alpha decay are presented. Systematics and energetics involved in alpha decay are presented. The correlation between Q value and decay energy is described. The Geiger Nuttall relationship is provided, described, and utilized in a model for alpha decay. Tunneling is also exploited to described alpha decay, coupling energy and half-life. Gamow calculations are shown to reflect the Geiger Nuttall relationship. Hindered alpha decay is discussed. Hindered alpha decay is employed to described nuclear properties. Hinderance factors are described, along with how they are calculated and where they can be found. Proton and other charged particle emission are presented.

32 comments:

  1. The material in this lecture is a bit harder compared to the others but still manage able. All in all great lecture and cannot wait till next weeks lecture.

    ReplyDelete
  2. Thank you for the interesting lecture! I definitely agree with the comment above, but I'm still enjoying the material. I find the sections from the Modern Nuclear Chemistry book to be especially helpful in clarifying what I don't understand in the lecture.

    ReplyDelete
    Replies
    1. thanks for comments, especially regarding the reading material.

      Delete
  3. The homework questions provided at the end of the lecture were useful in determining whether or not I fully understood the material in the lecture.

    ReplyDelete
    Replies
    1. thanks for the comment. That is the concept with the PDF quizzes. I appreciate the feedback.

      Delete
  4. I find the PDF quizzes really helpful because they help me to really focus on what we are supposed to learn and get from the lecture.

    ReplyDelete
  5. For question 1 please make sure you provide the alpha decay energy, not the Q value. The Q value is the total energy of the system. The Q includes the alpha decay energy and the daughter. The alpha decay energy is always slightly less than the Q value.

    ReplyDelete
  6. The pdf quizzes allow me to gauge on what I have learned and what I still need to work on. I can start to see how other material from previous lectures tie in.

    ReplyDelete
    Replies
    1. excellent. I am happy to hear about the previous lectures.

      Delete
  7. After completing the lecture and quiz, I do not understand what is meant by daughter recoil. Does it have to do with calculating the frequency?

    ReplyDelete
    Replies
    1. I was a bit confused by this as well. I assume that "Daughter Recoil" refers to the kinetic energy of the daughter nucleus after the decay event. It helped to draw an analogy between decay and a collision problem from an introductory physics class, where the products of the collision have new kinetic energies similar to how decay products have kinetic energies. I'm not sure if this is accurate, though and wonder if anyone could correct it?

      Delete
    2. The daughter recoil comes from this concept. The Q value is the total energy from the decay. The alpha decay energy and the daughter recoil energy come from the Q value. The daughter has recoil due to the fact that for every reaction there is an equal and opposite reaction, from Newton's law of motion.

      The alpha decay energy is generally on the order of MeV. The daughter has a recoil energy on the order of keVs. This compares with bond energies, usually measured on the order of eV.

      Delete
  8. This comment has been removed by the author.

    ReplyDelete
  9. The PDF quiz helped me clear up confusions I had about the terms "Alpha Decay Energy" and "Q value" and their relationship to each other. I appreciate the feedback given to my PDF Submissions, but couldn't help feel that it would be a bit unproductive on a future assignment if many students had similar problems that each emailed their results and got similar feedback one at a time from Dr. Czerwinski. It might be more efficient if there were a way to submit our responses on the blog and collaborate on problem solving methods together. I'm not entirely sure how such a system could be designed to ensure that struggling students actually learn instead of getting the answers, or how it would even be implemented, but I think something like that might improve this class, and online education in general, if done correctly.

    ReplyDelete
    Replies
    1. Thanks for the comment. After seeing a few of the quizzes I added the comment on the blog so others would see it. So far I am very pleased with the feedback and response.

      Delete
  10. After viewing the lecture I was also confused about the Q value of alpha decay, but after reviewing the slide and viewing the blog comments the difference between the Q value and alpha particle kinetic energy is clear. Also thanks for including the conceptual review questions at the end of the lecture.

    ReplyDelete
    Replies
    1. thanks for the comments! I am glad to hear the Q value and the decay energy are clearer.

      Delete
  11. Information abounds in this lecture, almost a tad overwhelming.
    I believe there is a typo on slide 4, in the example for U-238. The Q-value was calculated as 4.270, but where it is input into the equation the number was changed to 4.720. However, the decay energy calculated is correct for the 4.270 value.

    ReplyDelete
  12. Thanks for the comment. Corrections on the way.

    ReplyDelete
  13. I've finished the lecture and submitted the quiz. Thank you for your above explanations in the blog. They've really helped clear things up.

    ReplyDelete
  14. thanks for the comments and the quiz submission!

    ReplyDelete
  15. Sorry I forgot to comment! I watched the lecture video and submitted the quiz!

    ReplyDelete
    Replies
    1. Thanks for the comment Marko. I have not received the quiz yet.

      Delete
  16. I really enjoyed this lecture, because it takes the concepts that we briefly discussed and gives a much more thorough explanation. This is a great way to teach this since there is so much material to cover and if not broken up would be quite overwhelming. Thank you again for the office hours, they helped immensely.

    ReplyDelete
    Replies
    1. thanks for your comment. I appreciate the feedback on the lecture structure

      Delete
  17. This lecture finally makes more sense. The beginnings were very broad and now I feel like we are narrowing the material down.

    ReplyDelete
    Replies
    1. happy to see things are coming together in the lectures

      Delete
  18. Alpha decay seems like the easiest to understand out of all the decays to me. The neutrino concept blows my mind my mind with turning protons into neutrons or vice-versa in beta decay, but this makes sense.

    ReplyDelete
    Replies
    1. thanks for your comment comparing the decay methods.

      Delete