Cross-sections for 43Sc, 44mSc, and 44gSc from two heavy ion reactions

Abstract

Two different heavy ion reactions were used to produce ⁴³Sc (t${}_{\frac{1}{2}}$ = 3.891 h), ${}^{44g}$Sc (t${}_{\frac{1}{2}}$ = 4.042 h), and ${}^{44m}$Sc (t${}_{\frac{1}{2}}$ = 58.61 h) among other stable or long-lived chemically separable products. Production cross sections for ¹⁹F + ²⁷Al and the reverse kinematic reaction ³⁵Cl + ${}^{nat}$B were measured using an MC-SNICS ion source and the Notre Dame FN Tandem Accelerator. ¹⁹F beams from 35 to 60 MeV were produced with beam currents between 40–80 pnA and ³⁵Cl beams were produced at six entrance energies with comparable beam currents. This work reports nuclear reaction cross sections ²⁷Al (¹⁹F, x) ⁴³Sc, ²⁷Al (¹⁹F, pn) ${}^{44g}$Sc, and ²⁷Al (¹⁹F, pn) ${}^{44m}$Sc at six energies between 35 and 60 MeV lab energy. Cross sections within the same energy range were measured for ²⁷Al (¹⁹F, 3pn) ⁴²K and ²⁷Al (¹⁹F, 3p) ⁴³K. Comparative measurements were performed for the same compound nucleus produced from ${}^{nat}$B(³⁵Cl, x) ⁴³Sc, ${}^{nat}$B(³⁵Cl, pn) ${}^{44g}$Sc, and ${}^{nat}$B(³⁵Cl, pn) ${}^{44m}$Sc. The measured thin target cross sections show an overestimation by several statistical models for the scandium radioisotopes. This is corroborated by the measured thick target production rates for both entrance channels. This may be due to angular momentum effects of a heavy ion entrance channel compared to light-ion production, but additional work is required to understand this discrepancy. These measurements demonstrate that the medically useful ⁴³Sc, ${}^{44g}$Sc, and ${}^{44m}$Sc radioisotopes can be free of the long-lived contaminant ⁴⁶Sc without the use of enriched targets, using heavy ion beams and robust target materials.