The radionuclide $^{169}$Yb (T$_{1/2}$ = 32 d) decays with emission of Auger electrons and X-rays, which can be used for brachytherapy. We have systematically investigated the production routes of $^{169}$Yb through charged-particle induced reactions. Deuteron- and alpha-induced reactions on $^{169}$Tm and alpha-induced reactions on $^{\rm nat}$Er have already been studied. Recently an experiment of the proton-induced reaction on $^{169}$Tm was performed. In this paper, we report the preliminary result of this experiment.

The experiment was performed using the MGC-20E cyclotron at Institute for Nuclear Research (ATOMKI), Hungary. The stacked foil activation technique and the high-resolution gamma-ray spectrometry were used. Pure metallic foils of $^{169}$Tm (21.0 mg/cm$^{2}$, 99.0% purity) and $^{\rm nat}$Ti (9.1 mg/cm$^{2}$, 99.6% purity) were stacked as a target. The target was irradiated for 30 min by an 18 MeV proton beam with 210 nA. Gamma-ray spectra were collected for the irradiated foils by a HPGe detector.

Our preliminary result of the $^{169}$Tm(p,n)$^{169}$Yb reaction is shown in Fig. 1 in comparison with the previous experimental data [1-3] and the TENDL-2017 data [4]. The peak amplitude of the result is normalized to the data of Birattari et al. (1973) 1. The detailed analysis is being performed.

Reference

1. C. Birattari et al., Nucl. Phys. A 201 (1973) 579.
2. I. Spahn et al., Appl. Radiat. Isot. 63 (2005) 235.
3. F. Tarkanyi et al., Appl. Radiat. Isot. 70 (2012) 309.
4. A. Koning and D. Rochman, Nucl. Data Sheets 113 (2012) 2841.