
This README file provides instructions for reading the radioactive decay 
schemes in the files zXX.aYYY found in the directory RadioactiveDecay4.0
(most recent version).  This directory, as well as previous versions, is
available from the Geant4 download page 

http://cern.ch/geant4/support/download.shtml

under the Data files heading. In order to use the radioactive decay module
correctly, you must download and unpack the above directory in your local
area, and set the environment variable

G4RADIOACTIVEDATA

to point to it. 

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In each of the files, lines beginning with either a 'W' or a '#' are 
comments.

Lines beginning with a 'P' are headers, indicating metastable states of the
nucleus which may be parent nuclei for further decays.  The first number is
the excitation energy in keV and the second is the half life in seconds.
Indented lines under the 'P' lines are decay modes for that excitation.
There are two types of records here, distinguished by the number of columns.

If there are 3 columns only, this is a header describing the total strength
of each type of decay from this level.  The first column is the decay mode,
the second column is always zero, and the third column is the total branching
ratio going through this mode, as a fraction of unity.  Therefore, the third
column of all the 3-column records under a given 'P' line should sum to 1.0.

If there are four columns, this is a record which describes a subset of the 
decay type, specific to a given lower level in the daughter species.  The 
first column is the decay type, the second column is the excitation level
(keV) of the daughter reached after the decay, and the third column is the
branching ratio as a percentage (! note... not a fraction of unity) of the 
total branching ratio which came from the 3-column record for this decay.

In the case of beta- or beta+ decay, there will often be a fifth column
describing the "forbiddenness" of the particular decay channel.  This is
indicated by the tags firstForbidden, secondForbidden, thirdForbidden,
uniqueFirstForbidden, uniqueSecondForbidden, uniqueThirdForbidden, which
determine the shape of the beta spectrum.
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