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59,202 Views ⢠Jan 7, 2024 ⢠Click to toggle off description
Step-by-step guide on how to derive and solve the neutron diffusion equation to determine the critical mass of an atomic bomb. It involves solving a partial differential equation but every step is presented. In the end a general formula for a nuclear critical mass is found.
Relevant links:
⢠Critical Mass: when the atomic bomb got real    â˘Â Critical Mass: when the atomic bomb g... Â
⢠Physics of a Nuclear Explosion    â˘Â Physics of a nuclear explosion Â
⢠Nuclear Weapons Q&A #1    â˘Â Nuclear Weapons Q&A #1 Â
⢠Series on Nuclear Weapons Physics    â˘Â Physics of Nuclear Weapons Â
⢠"Critical Assembly Simulator" by Alex Wellerstein blog.nuclearsecrecy.com/misc/criticality/
⢠The Feynman Lectures on Physics www.feynmanlectures.caltech.edu/
Errata:
⢠at 10:10 the Laplacian of f should say: â²f= (1/r²)*d/dr(r² df/dr) (not 1/r² in the derivative bracket), this is a typo and not an error in the calculation; thanks to @fatassmonkey37 for pointing this out
⢠at 15:58 the subscripts are reversed, it should say: Ν_f = 16.89 cm, Ν_t = 3.596 cm; thanks to @lucacastronuovo9789 for pointing this out
Credits:
"Critical Assembly Simulator" courtesy of Alex Wellerstein blog.nuclearsecrecy.com/misc/criticality/
Diffusion by JrPol under CC BY 3.0 Deed creativecommons.org/licenses/by/3.0/deed.en
Metal cube by JOGOS Public Assets under CC BY-SA 4.0 Deed creativecommons.org/licenses/by-sa/4.0/deed.en
Chapters:
00:00 Neutron diffusion equation
05:41 Solution
15:24 Critical mass
20:13 Advanced solution
Views : 59,202
Genre: Science & Technology
Date of upload: Jan 7, 2024 ^^
Rating : 4.975 (18/2,887 LTDR)
RYD date created : 2024-05-18T13:57:35.04316Z
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YouTube Comments - 350 Comments
Top Comments of this video!! :3
Absolutely fascinating. I have always been interested how this was calculated ever since I did a school assignment on the Manhattan project when I was 14 in 1974.
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17:15 This will very quickly start blowing up LOL, I've often heard of exponentials "blowing up" but here, never a more true definition đ
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This is the first time that I am excited for a homework assignment and I can't believe it came from YouTube, I really want to try to do this! Brilliant video and thanks for educating us on this fascinating topic!
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Man, I am a high schooler and I am trying my best to learn Physics, a subject that I love with all of my heart, I am self studing calculus to, one day, contribute a little to this wonderful field, the things that I find more interesting are the possibilities that the Island of stability can give us, and I want to dedicate my life to that.
Take my money (earned by surveys so no problem for me) and buy a cup of something
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This channel deserves more views and subs, one of the best Physics YT channels out there keep it up!
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Not going to lie, the maths is a bit beyond me, but I love how you worked out the critical masses. All of your videos have been amazing and I always look forward to the next one.
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You know itâs a good day when you get a notification for Dr. Jorge S. Diaz đĽ
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Shame how underrated this channel isđ˘
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Thank you for this video, I got stuck while working on building my atomic bomb and this was very helpful.
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Thank you I was trying to find this for a long long time
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This is an amazing video! Made me even more excited to learn DPEs next semester!
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Wow, so well explained. Such advanced physics explained step by step. I hope more people checks your wonderful channel
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The Differential Equation of DOOM :)
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A coffee/beer from a nuclear colleague from Poland, with kind regards!â
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Very underrated YouTube channel.
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That's worth a coffeeâ
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Thanks. I'll make sure to employ this new information... wisely...
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Actually, I am amazed by your work. I donât know what to say. I thought a lot about the effort you made to make this video. It must have been hard. I donât think anyone can thank you as you deserve. In fact, I am traveling to Russia, where there are no means of support or Communication with the outside world, even YouTube ads are prohibited, so I turned on a VPN so that ads would appear on your videos and I could watch them. Indeed, I watched 14 ads and visited 11 advertiserâs websites. This took some time, but it is nothing compared to the time that you spent making this video, and perhaps this is worth a few cents to the channel, but I feel that it is more moral support than material support. Thank you from the bottom of my heart, you brilliant mind.â¤
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Excellent! Could you make a video on the implosion physics ? For example, it is often said that although it was known that hollow cores would have a much better yield, the original bomb used a "conservative" design based on a solid core ("Christy core") because the maths of hollow core implosion was too difficult to solve at the time (but it was finally implemented in all designs a few years later). I could not find any more detailed info on that on the web.
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@jakubstawarczyk
4 months ago
Amazing, as a theoretical physicist myself, I'm looking forward to see more mathematical videos about this topic đ
Edit: makes me wanna sit down with numerical methods and analyze more reallistic example of shrinking and expanding core (true R(t))
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