Assigned:
23-Jan-19
1st Due Date: 28-Jan-19
2nd Due Date: 31-Jan-19
Lecture 1: Introduction, Chart
of the Nuclides
Lecture 2: Nuclear Properties
Lecture 3: Decay Kinetics
Lecture 4: Alpha Decay
Lecture 5: Beta Decay
Use lecture notes, textbooks, Chart of the Nuclides, Table of the
Isotopes, and web pages. Use the chart
of the nuclides as your primary dataset for isotope half-life. For
the second submission, show your work or references on a separate page and save
electronically. Please use 3 significant digits for your answers. Scientific notation should be written as
1.23E4 rather than 1.23x10^4.
A few questions on the quiz (warning, they may be VERY stupid):
ReplyDeleteA) In question 8 what does equilibrium mean and how do we calculate it?
B) In question 10 how do you find the cross sectional area?
C) In question 11.4 do you mean the most likely decay?
More questions potentially to follow
The use of cross section is found starting on page 39 of lecture 3. Cross section data is found in the table of the nuclides as described in lecture 1, starting on page 29.
DeleteThe most likely decay is the decay with the greatest probability.
Deletethanks for your questions
DeleteEquilibrium is discussed in lecture 3, slide 31. A key term for secular equilibrium is A1=A2. You can read about equilibrium starting on page 194 in Nuclear and Radiochemistry. The weblinks in the Decay Kinetics lecture also have information on equilibrium.
For question 10, the cross section data is blurry, I can't really tell the numbers..
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ReplyDeletePlease continue to post any questions.
ReplyDeleteWhat exactly is question 2 asking based off the chart? I'm unsure what to be measuring the radii for.
ReplyDeleteThe target isotopes are stable 90Zr and 197Au. The radii, as distance of closest approach, are measured with alpha particles emitted from the 3 radioactive isotopes in the table.
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ReplyDeleteI'm having difficulty figuring out the decay chain from 229Th to 225Ac for problem 8.4. Also, in 8.5 you want mass in grams, not Bq, right?
ReplyDeleteThe decay chain can be found in the chart of the nuclides. You can alos search for the decay chain online.
ReplyDeleteFor mass use g, Bq is not a mass unit.
In 8.5 the unit should be written at g, not Bq
DeleteI thought so, but you never know when some people like their units weird
DeleteFor problem 2, are we allowed to use any of the four values that are listed on the website? Or would you rather us choose a specific one?
ReplyDeleteOne more thing, could you clarify if the "1.55 Bq" supposed to be in grams or Bq's? I'm using lecture 3 slide 16 as my formula, but I can't see how Bq would work in this scenario.
DeleteSee above. It should list g not Bq.
DeleteKen, for calculating % error, are we supposed to use the sigma^-1 formula found on lecture 3, slide 9?
ReplyDeleteYes, that is it! The error is square root of the total counts. This can be used to find the percent error.
ReplyDeleteFor problem 11, is there a specific way of calculating hindrance factors? I don't quite remember if this was covered in lecture and I can't seem to find it, if it was.
ReplyDeleteSee lecture 4, page 15.
DeleteSome general comments on the exam.
ReplyDeleteFor question 3 remember 212Bi has branching decay.
To calculate the decay constant the half life should be in seconds. You may need to convert the half life from another time unit.
I'm still stumped on 8.2, could we use the formula on lecture 3, slide 27 at all?
ReplyDeleteLook at lecture 3, slide 15. For question 8.2 you need to know the 225Ra activity at equilibrium. If one knows the activity (A), use the equation
DeleteA=lambda*N, where lambda is the decay constant and N is the number of atoms. If you know the number of atoms then you have all the information you need.
Celebration of knowledge 1 is finished and uploaded to canvas. Good luck to the rest of you!
ReplyDeleteFor question 2, I'm not sure if I have the units right. So I'm using Z for the target nucleus, and the T as the alpha decay energy from the given molecule like 210Po in MeV. If I use MeV is that result of d0 in fm as shown in the equation? Because I thought MeV is based off the Joule which is based in meters.
ReplyDeleteThe equation presented, do=2.6Z/T is derived from the fundamental equation do=2Ze^2/T. If you set do in fm and T in MeV the fundamental equation then becomes do=2.6Z/T for the specific case.
DeleteMy celebration of learning is submitted! Via both canvas upload, and emailed with the submit button.
ReplyDeleteI may have submitted twice via email, my computer glitched a bit the first time I tried.
the exam was submitted via submit button.
ReplyDeleteCompleted and submitted via Canvas and the pdf submit button
ReplyDeleteCompleted and submitted! :)
ReplyDeleteSubmitted the exam.
ReplyDeleteExam submitted through canvas.
ReplyDeleteSubmitted!
ReplyDeleteExam submitted
ReplyDeleteSubmitted the exam via Canvas and form.
ReplyDeletesubmitted exam
ReplyDeleteI am starting to work on the second submission of exam 1 since the key have been posted this morning. How are the rules of significant figures enforced? If I have an answer that is 3.94E9 while the answer key has 3.93E9, will I still received full credit or only half credit from the correction of second submission. I just would like to point out that sig figs are not enforced in quizzes grading and only mentioned by one line at the beginning of the exam, so I do not know how harsh it will be graded on. Thank you!
ReplyDeleteThanks for the comment on the significant figures. Honestly this just makes it easier for me to grade. I would prefer if the significant figure values were consistent with the key. I am rather unlike to subtract points on this matter.
DeleteIf the answer is 3.94E9 and you provided 3.93E9, you would get full credit. One should expect some minor variations in calculation. For example I could ask for the decay constant of 229Th. From my examination of the literature there are 3 different half-life values for 229Th. I should therefore expect a potential range of values for the decay constant.
Thanks for asking your questions!
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ReplyDeleteI am working on corrections for exam 1, I was unsure of how to do question 10. How do I go about solving this problem?
ReplyDeleteReview lecture 3, starting on page 38. Follow the example on page 41. If you have further questions please post.
DeleteWhen looking at the answers for question 3 it seems that you used the small lambda*t assumption for all count times though in the slides it says this only applies for small relative count times to the half life. In my calculations the first two are similar when using the full equation but there seems to be a rapidly growing difference. Why would we use the assumption all the way through? I only used the short hand on the very first one as reference.
ReplyDeleteFor question 3 the answers should provide the expected total counts and the error from the counts.
DeleteI question 10 half life of 198Au is on the order of the irradiation time, so the saturation factor should be used.
Hi, Prof. Czerwinski.
ReplyDeleteI was wondering whether we would be able to submit corrections for multiple choice questions? For example, on 6.5 I misread the question as a multi-answer one and selected Np-236, Np-237, and U-233 (based on this table). The answer you have in the key is Np-236 - would my answer be considered correct or incorrect?
Thank you in advance!
Oh! I also noticed in your post that you expect a range of answers due to discrepancies in literature values. For 1.2, I had the density of a neutron star as the average of all four values listed on the website rather than choosing just one value - would this also be considered incorrect?
DeleteThanks again!
With the explanation your answer would be correct. The average value for the neutron star density would be acceptable. I am looking for an order of magnitude answer.
DeleteI'm looking at the key for the exam, and I had a couple of questions.
ReplyDelete1) For question 3, I only submitted the amount of full counts that could be completed in that time. I did not think that a part of a count could be counted, only full counts. Would my answer be considered correct? (For example. in the first part of the chart, I only listed that 4 counts would be completed in 30 s)
2) As someone asked earlier, if there are multiple choice questions, can we still receive credit back if we provide an explanation for why the correct answer is correct? For example, question 6.5.
Thank you
For part one, the full unit count would be considered correct. One can get fractional count depending on the units used. For example if the counts are in counts per minute, is it easy to get fractional units when converted to counts per second. Your comments certainly clarify your answers.
DeleteFor part 2, explanations on your selections are most certainly considered.
I have a question for the exam submission. For the first submission, I just did questions and filled the blanks and clicked "submit form". I wonder if work process is also needed for the first submission or it is just for the second submission?
ReplyDeleteThanks.
It should work either way. I will check to make sure your submission was sent. If there are any issues I will let you know.
DeleteI just re-submitted my Exam 1. I provided explanations for my fixed answers with comments on the PDF, colored red. If anything is not readable or requires further explanation, please let me know!
ReplyDeletethank you!!
DeleteRe-submitted exam one with corrections as comments in red as well! I can also explain more if needed
ReplyDeleteI've resubmitted the test corrections with explanations and formulas required, they are in red.
ReplyDeleteRe-submitted my exam corrects--comments are next to them in orange boxes!
ReplyDeletecorrections*
Delete(I couldn't help myself)
Thanks!!
DeleteExam 1 corrections submitted
ReplyDeleteSubmitted my corrections in a separate document along with my original exam as I believe I've fixed my form problem, please let me know if it isn't working properly. Comments with the math applied are next to the corrected answers!
ReplyDeletethanks for the submission!
ReplyDeleteResubmitted with the corrections
ReplyDeleteResubmitted with corrections. Ideally, should we send resubmissions through email or upload them on Canvas? Thanks!
ReplyDeleteI forgot to mention - the questions I corrected have a "checkmark" stamp next to them. And the corresponding calculations should be in a separate pdf.
DeleteTerrific. Thanks for the notifications.
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