  Measurements of the drift velocities of electrons and holes as functions of
electric field and temperature in high-purity n- and p-type silicon with <100>
crystal orientation are presented. The measurements cover electric field values
between 2.4 and 50 kV/cm and temperatures between 233 and 333 K. Two methods
have been used for extracting the drift velocities from current transient
measurements: A time-of-flight (tof) method and fits of simulated transients to
the measured transients, with the parameters describing the field and
temperature dependence of the electron and hole mobilities as free parameters.
A new mobility parametrization, which also provides a better description of
existing data than previous ones, allowed an extension of the classical tof
method to the situation of non-uniform fields. For the fit method, the use of
the convolution theorem of Fourier transforms enabled us to precisely determine
the electronics transfer function of the complete set-up, including the sensor
properties. The agreement between the tof and the fit method is about 1 %,
which corresponds to a time-of-flight uncertainty of 30 ps for a pad diode of
200 {\mu}m thickness at the highest voltages. Combining our results with
published data of low-field mobilities, we derive parameterizations of the
drift velocities in high-ohmic <100> silicon for electrons and holes for fields
between 0 and 50 kV/cm and temperatures between 233 and 333 K.
