From: g_d_pusch_remove_underscores@xnet.com   
      
   I wrote:   
      
   > Muon mean range is about 1.8 km in vacuum; in most forms of matter   
   > (including air) muon range is around 1 gm/cm^2 at energies above 100 MeV,   
   > so dividing by the sea-level density of air, the muon mean range is about   
   > 8.5 meters.   
      
   ...Unfortunately, however, I have just realized that I was reading   
   the wrong curve on the graph in the Particle Data Book; the actual muon   
   range is on the order of 200--300 gm/cm^2, so the muon range in air   
   is essentially the same as in vacuum. Mea culpa... :-(   
      
   This implies that the energy deposited in the air around the bomb will be   
   even more diffuse than I had thought, further weakening the already weak   
   "blast effect" component, and making a "pure" matter/antimatter bomb w/out   
   a high-Z "tamper" even more nearly an "enhanced radiation weapon." To get a   
   high explosive yield out of the thing, one will need to wrap it in a tungsten   
   or uranium "tamper" to absorb the charged pions and the pi-zero decay gammas   
   (the latter would be more than a little "dirty," since the energetic pions   
   and pi-zero decay gammas will induce a lot of fissions and photofissions...).   
      
      
   -- Gordon D. Pusch   
      
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