A low-cost small-size commercial PIN photodiode: II. Comparison of measurements with monoenergetic electrons to analytical expressions and Monte Carlo simulations

Abstract

<p>Commercial PIN photodiodes, repurposed as particle detectors, have received a lot of attention along the past</p><p>decades because they can offer a low-cost solution suitable for several applications. The BPX-65 photodiode has</p><p>been chosen because of its interesting features for measuring electrons in a harsh radiation environment close to</p><p>the beam of an accelerator. Its electrical characterisation and its application to photon spectrometry have been</p><p>presented in the companion paper I. Here, its response function (RF) to electrons is investigated using the beam</p><p>from an electron accelerator with a small energy spread. The empirical expressions for the RF available in the</p><p>literature have been improved, simplified, and combined to obtain a final form with 7 free parameters: 4 nonlinear</p><p>and 3 linear. A special fitting procedure, which takes advantage of the presence of the linear parameters,</p><p>is described. The behaviour of these parameters with beam energy and bias is investigated to uncover the</p><p>physical origin of the three components included in the proposed RF. The interpretation of the features of the</p><p>spectra is confirmed by Monte Carlo simulations carried out employing the general-purpose PENELOPE/penEasy</p><p>package. To take into account the charge-collection properties of the device, a simple model has been implemented</p><p>and is compared to data. It has then been possible to estimate the thickness of the partially dead layer</p><p>from the experiment.</p>