Alpha spectrometry with the inexpensive open-source detector Alphaino

A photodiode-based inexpensive detector working as counter and spectrometer for alpha particles, named Alphaino, is described and analyzed in depth. Prior to detector construction, Monte Carlo simulations by means of MCNPX ver. 2.7.0 code have been carried out to select the most suitable sensitive element for the intended applications. The detector has been tested for low-rate alpha-particle counting and spectroscopy, demonstrating a maximum achievable count rate of $4\cdot 10^3$ s⁻¹, with an energy resolution corresponding to a Full Width Half Maximum of 160 keV over the entire energy range of measured alpha, namely $4-6.5$ MeV, the intrinsic efficiency being 100%. Alphaino can be used for fast and qualitative analyses to radionuclides identification, and quantitative analyses when radionuclides monitored are characterized by well distinguished energy lines in spectra. Its applications will include ²²²Rn progeny monitoring by mechanical air sampling on a millipore filter, and disposable applications to qualitative measuring of potentially alpha-contaminated liquids (containing plutonium isotopes) by a droplet put on the photodiode itself, for a quick and cheap evaluation prior to initiate proper chemical treatments to classical alpha spectrometry by electrodeposition. Alphaino is completely open-source. The repository for the project is available on GITHUB at https://github.com/bemxgm/Radon-Monitor.