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Forum: Hadronic Processes
Re: Warning RadioactiveDecay lacks factor ln(2) in decay width-half life conversion (Mikhail)
Date: 24 Oct, 2015
From: Dennis H. Wright <Dennis H. Wright>

Hi Mikhail,

   Looking through the alpha emitters in RadioactiveDecay4.2, the half-life values listed there are in good agreement with those listed in the nuclear wallet cards (www.nndc.bnl.gov);  there is no missing factor of ln(2).   I looked at 230Th and 210Po, for example.   

   As you mentioned, almost all of the low-mass alpha emitters (5He, 7B, etc.) have been removed from
RadioactiveDecay since version 3.4.  The reason this was done is that the ground state lifetimes were very short and we interpreted this to mean that the process was not radioactive decay, but nuclear fragmentation.  Soon we plan to add such things as radioactive proton and neutron emission, but for now they do not exist in the code.

  This leaves us with the remaining case of 8Be.  Here, the wallet cards list the width as 5.57 eV.   Since it is a width and not a lifetime, we first get the mean-life = 6.582 x 10**-16 eV s / 5.57 eV = 1.18 x 10**-16 s.  The half-life is then 0.693*1.18x10**-16 = 8.19 x10** -17 s, in agreement with the value in RadioactiveDecay4.2.   

  In short, all the files in RadioactiveDecay4.2 seem to be OK as they are.

Dennis

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