Radiochemical Determination of Long-Lived Radionuclides in Proton-Irradiated Heavy-Metal Targets: Part I-Tantalum.

In this study, distillation, precipitation, and ion-exchange methods were chosen for the separation of the long-lived β-emitters129 I,36 Cl and the α-emitters154 Dy,148 Gd,150 Gd, and146 Sm from Ta targets irradiated with protons up to 2.6 GeV to determine their production cross sections. Measurements of129 I/127 I and36 Cl/35 Cl ratios were performed with accelerator mass spectrometry. After separation of the lanthanides, the molecular plating technique was applied to prepare thin samples to obtain highly resolved α-spectra. Autoradiography and focused ion beam/scanning electron microscopy techniques were used to characterize the lanthanide deposited layer. Experimental cross-section data are compared with theoretical predictions obtained with INCL++ and ABLA07 code, and a satisfactory agreement is observed.