Computational evaluation of a novel beta radiation probe design using integrated circuits

Researchers at Texas A&M University (TAMU) have designed the radiation integrated circuit (RIC) for deployment as a new radiation detection system. Most integrated circuits are susceptible to radiation-induced failures, and decades of research have gone into solving this problem. Research at TAMU has led to a novel integrated circuit design that utilizes both radiation-hardened areas (RHAs) and radiation-sensitive areas (RSAs) to take advantage of these failures. The RSAs are susceptible to charged particle interactions, allowing the RIC to detect alpha and beta particles. However, beta particles are more penetrating compared to alpha particles, resulting in a lower interaction probability for beta particles incident on a bare RIC. In any material, the higher the beta energy, the deeper the beta particle can penetrate; therefore, the use of a wedge-shaped attenuator for beta particle detection not only increases interaction probability, but also provides the capability to perform maximum beta energy discrimination in the field. The objective of this research was to optimize the design of the RIC. Monte Carlo N-particle radiation transport code (MCNP) simulations assessed the beta particle detection and maximum energy discrimination performance of plate glass, borosilicate (Pyrex®) glass, acrylic (Lucite®), and natural rubber attenuators. In this proof-of-concept analysis, natural rubber was observed to be the optimal attenuating material for the beta probe with respect to maximum energy discrimination capability and weight, but all materials considered proved to be good candidates. The results of this study are promising and indicate the potential to achieve maximum beta particle energy discrimination of 50 keV using a wedged, natural rubber attenuator on the RIC.

The Self-Absorption Effect of Ni-63 Beta Source to the Silicon Carbide based Betavoltaic Battery

A typical planar structure is the most feasible conceptual design of betavoltaic battery due to its simplicity. The self-absorption of beta source, however, causes a limitation to the geometrical efficiency. Herein, we tried to investigate the self-absorption event in Ni-63 beta source by changing the geometrical aspects and evaluated its effect on each layer of a 4H-SiC semiconductor as the radiation-electricity converter. The design configuration from previous literature was adopted and the model was developed using Monte Carlo N-Particle X (MCNPX) consists of radioisotope source, semiconductor, and also ohmic contacts. The energy of beta emission was adjusted to the actual Ni-63 beta spectra with an isotropic distribution of ejected particles. The average beta energy deposition degrades along with the addition of source mass thickness, but the n+ substrate has a unique result where a peak is observed at 0.1246 mg/cm2 due to the self-absorption effect. Furthermore, the rectangular surface area magnification gives a positive impact on the beta energy deposition up to 2.48% and the photon average energy deposition up to 137.21%. The results of average electron absorbed dose are consistent with Oldano-Pasquarelli semi-empirical theory of self-absorption in the beta source, where the upper layer receives a wider angular distribution of particles compared to the lower one, which corresponds to the counting geometrical coefficients.