Cross section data for the production of the positron emitting niobium isotope ⁹⁰Nb via the ⁹⁰Zr(p, n)-reaction

Abstract

The radioisotope 90 Nb decays with a positron branching of 53% and a relatively low β + -energy of E mean = 0.66 MeV and E max = 1.5 MeV. Its half-life of 14.6 h makes it especially promising for quantitative investigation of biological processes with slow distribution kinetics using positron emission tomography. To optimise its production, the excitation functions of 90 Zr( p, xn)-processes were studied over the proton energy range of 7.5 to 19 MeV via the stacked-foil technique using both nat Zr and 99.22% enriched 90 ZrO 2 as targets. Thick target yields of 90 Nb were calculated from the measured excitation functions and were verified experimentally. The optimum energy range for the production of 90 Nb via the 90 Zr( p, n)-process was found to be E p = 17 → 7 MeV, with a yield of 600 MBq 90 Nb/µA h. The yield and radionuclidic purity of 90 Nb over the energy range of E p = 17.6 → 8.1 MeV were determined experimentally using nat Zr. At 4 h after EOB the yield of 90 Nb was found to be 290 MBq/µA h and its radionuclidic purity ≥ 95%.

Excitation functions of natZr+p nuclear processes up to 70MeV: New measurements and compilation

“…[22] show good agreement with the general trend of the excitation function. Interestingly, the data of Busse et al [18], measured on enriched targets above 15.5 MeV, show a sharper decrease beyond the first peak maximum than any of the other data sets. However, their lower energy data points measured on both natural and enriched Zr samples are consistent with the majority of the previous results.…”

“…Except in the case of one work [20], all results locate the position of the first peak between 14 and 15 MeV [15,18,19,[21][22][23]25,26]. The entire excitation function based on the work of Kondtrat'ev et al [20] seems to be shifted by 3-5 MeV towards higher energies.…”

“…Note that due to the high natural abundance of 90 [18], the only previous investigators of the 90 Zr(p,2n) 89g Nb nuclear reaction, to our knowledge. Their converted data are shown in Fig.…”

“…A literature search for relevant experimental cross sections found 14 studies that reported excitation functions for Zr+p reactions in different energy intervals below 70 MeV [15][16][17][18][19][20][21][22][23][24][25][26][27][28]. All authors measured the activity of their irradiated samples non-destructively, i.e.…”

“…9. This process was investigated by the majority of the authors: nine of the fourteen groups who studied nat Zr+p presented cross sections for this process in different energy regions [15,[18][19][20][21][22][23]25,26].…”