Determining reaction cross sections via characteristic X-ray detection: α-induced reactions on 169Tm for the astrophysical γ-process

The cross sections of the Tm169(α,γ)Lu173 and Tm169(α,n)Lu172 reactions have been measured first time using a new method, by detecting the characteristic X-ray radiation following the electron capture-decay of 172,173Lu. Despite the relatively long half-life of the reaction products (T1/2=500 and 6.7 days, respectively) it was possible to measure the cross section of the Tm169(α,γ)Lu173 reaction close to the Gamow window (T9=3.5 GK), between Ec.m.=13.16 and 17.08 MeV. The Tm169(α,n)Lu172 reaction cross section was measured from Ec.m.=11.21 MeV up to Ec.m.=17.08 MeV. The experimental results have been compared to theoretical predictions.