[HN Gopher] Experimental and Theoretical Confirmation of Covalen...
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       Experimental and Theoretical Confirmation of Covalent Bonding in
       a-Pu
        
       Author : PaulHoule
       Score  : 31 points
       Date   : 2025-10-01 23:42 UTC (3 days ago)
        
 (HTM) web link (advanced.onlinelibrary.wiley.com)
 (TXT) w3m dump (advanced.onlinelibrary.wiley.com)
        
       | addaon wrote:
       | Why should the nuclear physicists have all the fun? Let the
       | chemists play too.
       | 
       | I assume the huge density difference between plutonium allotropes
       | contributes to making a density wave (explosion) an effective way
       | to trigger criticality?
        
         | PaulHoule wrote:
         | The chemistry and solid state physics of the actinides is
         | pretty interesting because of all the electrons whizzing
         | around: consider the infrared spectrum of thoria which makes it
         | the choice for gas light mantles or the glow in the dark
         | behavior of uranium glass which has nothing to do with
         | radioactivity.
        
           | HPsquared wrote:
           | Not forgetting the Lanthanides, their cousins in the f-block,
           | which have various interesting optical / catalytic / magnetic
           | properties (e.g. Europium, Cerium, Neodymium).
        
         | philipkglass wrote:
         | Lower initial density isn't really an advantage. If I recall
         | correctly, alpha phase plutonium was used in early nuclear
         | weapons cores because it was easier to shape. The brittle,
         | harder, denser delta phase (with mechanical properties
         | comparable to cast iron) was used in later weapons once the
         | difficulties of machining it were overcome.
         | 
         | The decisions made during the Manhattan Project were not aimed
         | at high efficiency nuclear weapons; the project needed to
         | ensure that reliable weapons could be constructed quickly with
         | the limited information available at the time. Even before
         | fusion weapons were invented, atomic bombs became significantly
         | more powerful, efficient, and lightweight due to realizing
         | design optimizations that couldn't be tested before the war
         | ended.
        
           | addaon wrote:
           | > Lower initial density isn't really an advantage.
           | 
           | Wouldn't larger change in density for a given force be an
           | advantage, though? It allows you to have a larger subcritical
           | mass (at the lower density) that becomes critical as force is
           | applied, without having to play geometric games; but maybe
           | those games are trivial?
        
             | jabl wrote:
             | AFAIU it is suspected that many(most?) bombs have hollow
             | cores; if so, they're already "playing geometric games".
        
       | trebligdivad wrote:
       | What does the word 'macropscopic' mean in it's abstract? The best
       | bet is a typo of macroscopic - but hmm it's made it through that
       | far and I do find a bunch of other uses of that word in physicsy
       | stuff
       | 
       | (The nice word in there is 'ansatzes' which I didn't know, as
       | something like a starting guess/assumption)
        
         | gus_massa wrote:
         | Guessing: macropscopic is a typo. Most dictionaries don't have
         | many technical words and you get use to click " _add to
         | dictionary_ ". After a few days it's not highlighted in any of
         | the authors or reviewers text editor and nobody notice it. If
         | you want to get fancy, call it " _click fatigue_ ".
        
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       (page generated 2025-10-05 23:01 UTC)