Assigned: 16
September 2014
Due: 23 September 2014
Quiz 1 office hours: 1000-1130, 18
September 14, 1st floor HRC
Lecture 1: Introduction, Chart
of the Nuclides
Lecture 2: Nuclear Properties
Lecture 3: Decay Kinetics
Use lecture notes, textbooks, Chart of the Nuclides, Table of the
Isotopes, and web pages. Show your work
or references on a separate page. Please post any questions related to the quiz on the blog.
Do we submit this quiz the same way we submit the other quizzes? And if so, do we need to scan our work/references and email that as well?
ReplyDeleteplease submit the quiz as the PDF quizzes. You can scan your work and sent in on a separate e-mail. Use the header Quiz 1: name
ReplyDeleteNeed to fix question 3.5 and republish
ReplyDeleteQuestion 3.5 on Quiz 1 corrected. I apologize for any inconvenience this may have caused.
ReplyDeleteI have a question about 5.4. The lecture on this graph mentioned that atomic numbers 56-59 are the most stable, meaning that fission and fusion reactions both tend to be exothermic until they approach those elements, but aren't all elements heavier than Nickel still formed via fusion by inputting energy in endothermic reactions? I don't recall a maximum atomic mass achievable by fusion or how A>240 elements are formed.
ReplyDeleteIn lecture 9 we will discuss the stellar nuclear reactions responsible for making the elements. We will see the fusion produces elements up to A=56. Above this to Bi isotopes the slow neutron capture process (s-process) produces the bulk of the stable isotopes. To reach elements with a Z greater the 83, the rapid neutron process (r-process) is necessary. Again this is covered in lecture 9. Excellent question!
DeleteFor question 9, would the number of atoms decrease? And do we include the saturation factor in calculating the activity?
ReplyDeleteThe number of 187W atoms, and the subsequent activity, increases until saturation is reached. The saturation equation is necessary for this question. The relevant section is lecture 3, production of radionuclides. An example of the saturation equation is provided with 59Fe and 56Mn.
ReplyDeleteERG program comments:
ReplyDeletewhen you download the ERG program is does not bring an icon to your desktop or launcher.
Once you download the program, search for ERG on your computer. On my computer the program is in:
C:Program files (x86)/ERG/Nuclide Tools
If you go here you should be able to open the NuclideTools application.
The answers to Quiz 1 are posted on the web page. Please review the answers with your submission. Make any changes to your quiz and resubmit. You will need to provide the work or comments with any changes to Quiz 1. Questions can be posted to the blog. Changes to Quiz 1 are due Monday 6 October.
ReplyDeletecomments on question 2
ReplyDeleteFor this question I want to find the neutron flux that gives me the same fission rate as the 239Pu decay rate. So all one needs to do is set equations equal to each other.
The 239Pu decay rate is
A=(decay constant)N
Solve this in decays per minute. This is what the fission rate should equal.
The fission rate is
R=N(cross section)(flux)
You want to solve for the neutron flux. N is the number of atoms
Set up the equations so A=R
(decay constant)N=N(cross section)(flux)
Rearrange and solve for flux
flux=(decay constant)/(cross section)
Question 3 comment.
ReplyDeletePlease review the guide for using the chart of the nuclides on page 44 and 45 of the chart of the nuclides. The information is also covered in lecture 1, part 2, page 14.
The cross section is for the reaction with the target. For producing 60Co from reaction a neutron on 59Co, the cross section data is on the 59Co isotope. In this case the nuclear reaction is (n,gamma). The neutron interacts with 59Co to make 60Co, so the relevant cross section in the interaction of 59Co with a neutron.
Sent in the corrected quiz 1 with an excel sheet for the questions that were corrected. Thanks for allowing us to correct the answers and see what was incorrect.
ReplyDeleteNo worries. I am still trying to figure out how to best organize the exams. This feedback is extremely valuable.
DeleteQuiz 1 answers with comments can be found at: http://radchem.nevada.edu/classes/chem312/quizzes.html
ReplyDelete