PMT is widely used in high energy physics experiments to detect single photons.
The PMT single photoelectron (PE) response (SER) is a template function
describing the pulse shape of single PE. In PMT waveform simulation and analysis,
the shape of SER are usually fixed for the one PMT.
This work proposes a linear model using multiple Gaussian parameters and
multiple basis, which allows SER to adjust its shape without introducing much
complexity such as non-linear and empirical SER formula. This model provides an
easy extension to PMT electronics simulation and waveform analysis. The
corresponding calibration algorithm is also developed and applied on real data,
which demonstrates the shape variance of PMT PE pulses.