  In many particle physics experiments the data processing is based on the
analysis of the digitized waveforms provided by the detector. While the
waveform amplitude is usually correlated to the event energy, the shape may
carry useful information for event discrimination. Thanks to the high signal to
noise ratio they provide, matched filters are often applied. Their original
design is however intended for the estimation of the waveform amplitude only.
  In this work we introduce an analytical extension of the original matched
filter for the estimation of a possible shape deformation with respect to a
reference template. The new filter is validated on simulations and, with
respect to shape parameters calculated on unfiltered waveforms or derived from
the original matched filter, it improves the discrimination capability by at
least a factor 2 both at low and high signal to noise ratios, making it
applicable to the data of several experiments.
