Stephan Heinitz

Production, separation and target preparation of 171Tm and 147Pm for neutron cross section measurements

Abstract The knowledge of the neutron capture cross sections of s-process branching point isotopes represents a basic requirement for the understanding of star evolution. Since such branching point isotopes are by definition radioactive, the measurement of their cross sections from thermal to stellar energies becomes a challenging task. Considerable amounts of material have to be produced, representing a significant radioactive hazard. We report here on the production and separation of 3.5 mg 171Tm from 240 mg 170Er2O3 and 72 μg 147Pm from 100 mg 146Nd2O3 irradiated at the ILL high flux reactor. Thin targets were prepared with high chemical and radioisotopic purity suitable for neutron capture measurements at n_TOF CERN and the SARAF-LiLiT facility.

Nucleosynthesis Reactions With The High-intensity Saraf-lilit Neutron Source

We present a status report of recent neutron capture experiments performed with the mA-proton beam (1.92 MeV, 3 kW) of the Soreq Applied Research Accelerator Facility (SARAF) and the Liquid-Lithium Target (LiLiT). Experiments and preliminary results for (n,gamma) reactions on 36,38Ar, studied for the first time with 30-keV neutrons, on natKr, natCe and on radioactive targets 147Pm and 171Tm are described.

Separation of weighable amounts of 10Be from proton irradiated graphite

Large amounts of 10Be are produced at the PSI muon production facility by high-energy proton spallation in polycrystalline graphite. For the extraction of 10Be out of large amounts of carbon, pyrolysis followed by chemical purification has been performed. Approx. 270g of graphite from Target E92, which had received a total proton charge of 29 Ah between 2002 and 2005, have been burned at 1000°C in a stream of oxygen. The volatile radioactive oxidation product 3H2O was trapped in 3 water bubblers connected in series. The remainder, a white hygroscopic solid material mainly consisting of 7Li2O, 9/10BeO and 10/11B2O3, was dissolved in HF and subsequently purified by ion exchange chromatography. Radioactive impurities such as 22Na, 44Ti, 54Mn, 60Co, 101Rh, 133Ba and 172Hf have been separated from the final product. The purified material represents a mixture of approx. 6.5mg 9Be and 3.5mg (3.3MBq) 10Be. It is ready to be used for scientific investigations requiring large amounts of this precious isotope.

A comparison between the chemical behaviour of lead-gold and lead-bismuth eutectics towards 316L stainless steel

Summary Lead-gold eutectic (LGE) has been recently proposed as an alternative target material for high power spallation sources. In order to compare the corrosive properties of LGE to the better-studied eutectic of lead-bismuth (LBE), an isothermal twin-loop made of SS 316L was built and operated at the Institute of Physics of the University of Latvia. We have measured the concentration of steel alloying elements dissolved in both alloys at the end of two test campaigns via ICP-OES. In case of LGE, a pronounced concentration increase of Fe, Ni, Mn and Cr is found in the liquid metal, which is significantly higher compared to LBE. Similar results were obtained during complementary investigations on material samples exposed to both alloys in this twin-loop at 400 ◦C and 450 ◦C. These findings indicate that in contact with LGE, SS 316L steel suffers from substantial chemical attack. Detailed investigations using structure materials other than SS 316L have to be undertaken before qualifying LGE as a serious alternative to LBE.