  Prototype SiPMs with 4384 pixels of dimensions $15 \times 15~\mu $m$^2$
produced by KETEK have been irradiated with reactor neutrons to eight fluences
between $10^9$ and $5\times 10^{14}$ cm$^{-2}$. For temperatures between
$-30~^\circ $C and $+30~^\circ $C capacitance-voltage, admittance-frequency,
current-forward voltage, current-reverse voltage and charge-voltage
measurements with and without illumination by a sub-nanosecond laser have been
performed. The data have been analysed using different methods in order to
extract the dependence on neutron fluence and temperature of the electrical
parameters, the breakdown oltage, the activation energy for the current
generation, the dark-count rate and the response to light pulses. The results
from the different analysis methods are compared.
