This README file provides instructions for reading the radioactive decay 
schemes in the files zXX.aYYY found in the directory RadioactiveDecay5.0
(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 '#' 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, followed by a character representing the floating
level.  If this is "-", the level is assumed to be fixed.  If it is
+X, +Y, +Z, +W, +U or +V, the level is floating, or undetermined.  The number 
following this 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 four 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, the third column indicates whether the level 
is floating or not, as mentioned above, and the fourth column is the total 
branching ratio going through this mode, as a fraction of unity.  Therefore,
the fourth column of all the 4-column records under a given 'P' line should sum
to 1.0.

If there are five 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 and third columns are the excitation
level (keV) of the daughter reached after the decay and its floating level 
indicator, and the fourth column is the branching ratio as a percentage
(! note... not a fraction of unity) of the total branching ratio which came 
from the 4-column record for this decay.

In the case of beta- or beta+ decay, there will often be a sixth 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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