The measurement of the Doppler broadening of annihilation
 line is very popular and frequently use in the positron
 annihilation studies. The typical setup consists with the
 germanium detector, a positron source with sandwiched two
 identical samples fixed in a holder. The setup requires
 also a multichannel analyzer which collects the measured
 spectrum.


 

    In this measurement we analyze the shape of the
 annihilation line (511 keV) obtained for several samples.
 Therefore we extract the so-called S-parameter which is
 defined as the ratio of counts in the central part to
 the total area of annihilation line. This parameter is
 sensitive to the low momentum electrons which mainly are
 present in the open volume defects. The increase of the
 value of this parameter indicates the increase of the
 number of these defects where positrons are localized.
 It is well visible in the presented example where the
 annihilation line measured for the well annealed and
 exposed to the compression copper sample are depicted.
 The sample after compression has visible more counts
 in the central part. It is also useful to extract the
 so-called wing W-parameter which is defined as the ratio
 of counts in the off central part to the total area of
 annihilation line. The W-parameter is more sensitive to
 the chemical surrounding of annihilation site than the
 S parameter, because core electrons having higher momenta
 are contributing mainly to the region of larger energy
 deviation from 511 keV.




 

    For the analysis of the annihilation line the SP has
 been written. This program allows to extract the
 the S-parameter and W-parameter after fitting the gauss
 curve to the experimental points and subtraction of the
 background. The maximum of this curve defines the 511 keV
 position what is important for definition of regions for
 integration procedure in the calculations of the S- and
 W-parameters. The program is freeware.
 Download:  Instal-SP-1.ZIP (2 MB).