  In recent years, particle discrimination methods based on digital waveform
analysis techniques for neutron-transmutation-doped silicon (nTD-Si) detectors
have become widely used for the identification of low-energy charged particles.
Although the particle discrimination capability of this method has been well
demonstrated for small incident angles, the particle discrimination performance
may be affected by changes in the detector response when the detector is moved
closer to the charged particle source and the incident position distribution
and incident angle distribution to the detector become wide. In this study, we
performed a beam test for particle discrimination in light-charged ($Z \le 2$)
particles using the digital waveform analysis method with a pad-type nTD-Si
detector and investigated the dependence of the performance of the particle
discrimination on the incident position and incident angle. As the incident
angle increased, a decrease in the maximum current was observed, which was
sufficient to affect the performance of the particle discrimination. This
decrease can be expressed as a function of the penetration depth of the charged
particles into the detector, which varies for each nuclide.
