Tailoring medium energy proton beam to induce low energy nuclear reactions in ⁸⁶SrCl₂ for production of PET radioisotope ⁸⁶Y

This paper reports results of experiments at Brookhaven Linac Isotope Producer (BLIP) aiming to investigate effective production of positron emitting radioisotope ⁸⁶Y by the low energy ⁸⁶Sr(p,n) reaction. BLIP is a facility at Brookhaven National Laboratory designed for the proton irradiation of the targets for isotope production at high and intermediate proton energies. The proton beam is delivered by the Linear Accelerator (LINAC) whose incident energy is tunable from 200 to 66 MeV in approximately 21 MeV increments. The array was designed to ensure energy degradation from 66 MeV down to less than 20 MeV. Aluminum slabs were used to degrade the proton energy down to the required range. The production yield of ⁸⁶Y (1.2+/−0.1 mCi (44.4+/−3.7) MBq/μAh) and ratio of radioisotopic impurities was determined by assaying an aliquot of the irradiated ⁸⁶SrCl₂ solution by gamma spectroscopy. The analysis of energy dependence of the ⁸⁶Y production yield and the ratios of radioisotopic impurities has been used to adjust degrader thickness. Experimental data showed substantial discrepancies in actual energy propagation compared to energy loss calculations. - Highlights: • High energy proton accelerator was used to produce ⁸⁶Y via low energy ⁸⁶Sr(p,n) reaction. • Proton energy was tailored by degradation. • Radioisotopic purity of yttrium fraction is comparable to that obtained in "small" cyclotron. • Energy loss calculations were not reliable