This lecture provides information on nuclear force and nuclear models. The strong force is introduced through isospin. A comparison of exchange particles is provided. The use of mirror nuclei to examine the strong force is presented. An overview of nuclear potentials is provided and used to discuss the shell model. States of the shell model and their relationship to magic numbers are discussed. Use of the shell model is determine nuclide spin and parity is presented. The relationship between spin and parity with nuclear deformation is introduced with Nilsson diagrams. Additional information on Nilsson diagrams can be found in the Table of the Isotopes. An introduction of the Fermi model for energetic nuclei is given. The lecture length is 53 minutes. The lecture is assigned on Saturday 27 January 2018 and due Thursday 1 February 2018. The answers to the Lecture 8 PDF quiz will be posted Thursday 2 February 2018.
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ReplyDeleteThanks for the PDF quiz and comment
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ReplyDeleteLecture done, quiz done. I'm a bit concerned with question 3 because none of my values matched the TOI except for the even-even nuclei. Is that the point or did I do something wrong?
ReplyDeleteThe shell model is based on spherical nuclei. If nuclei are not spherical then you would expect to see a difference between the spin and parity as measured and calculated by the shell model.
DeleteIf you examine the spin and parity of Hf isotopes, especially the metastable states, some very high and unusual spin states are observed.
DeleteExamples are below:
Delete177mHf 37/2-
178mHf 16+
179mHf 25/2-
This indicates the Hf nuclei are not necessarily spherical. If your shell model calculations do not match the spin and parity for a number of the Hf isotopes then you are very likely correct.
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ReplyDeleteThanks for the comments.
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ReplyDeleteBased on Nilsson diagram, does that imply nuclei have odd A numbers or odd number of nucleon (protons/neutrons) are usually deformed?
No usually. But even-even nuclei should be not be deformed. Deformed nuclei tend to have at least 1 unpaired nucleon.
DeleteLecture viewed, quiz submitted. I'm not sure about question 1, though; none of the elements have a Z (or N) equal to the magic number listed. Not sure what I'm forgetting.
ReplyDeleteUnnamed elements can be listed at Z= proton number. When I did my thesis work, we would write Rf as Z=104. In the question, the named elements are not magic, as you point out.
DeleteAh, ok! I got that wrong, then. Thanks!
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ReplyDeleteI have reviewed Lecture 8 and submitted PDF Quiz 8 by email
ReplyDeleteLecture 8 reviewed and submitted via canvas. I was wondering if Z=184 has added stability? From what I read it sounded like Z=184 only provides more stability for neutrons not protons. Also 184 is usually not listed with the magic numbers. Just wondering!
ReplyDelete-Sarah
This is Sarah Ostheller (student number 1671042), I'm on my sister's laptop so I wasn't signed in correctly! Sorry!
DeleteGreat comments. From the shell model in the quiz 184 is a magic number, so I would accept it. The point about neutrons is outstanding. It is also true the model ford not news to work for duch a high Z number.
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ReplyDeleteLecture viewed, I noticed I made a mistake on my first PDF quiz submission so i corrected it and resubmitted it.
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ReplyDeleteSorry for posting late - Ryan Cheung
no worries. I do not count this as late.
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