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43,44 Sc/ 47 Sc is one of the most promising theranostic pairs in nuclear medicine. The co-emission of 1157 keV γ-rays with 99.9% branching ratio by 44 Sc and the presence of its metastable state 44 m Sc push to favour the adoption of 43 Sc for Positron Emission Tomography (PET) diagnostic procedures to lighten the dose to the patient and to the personnel. The β + emitter 43 Sc can be produced at a medical cyclotron by proton bombardment of an enriched 43 Ca or 46 Ti oxide target. 43 Sc can be also produced by deuteron bombardment of an enriched 42 Ca oxide target. Only a few medical cyclotrons currently in operation offer deuteron beams. Some can be adapted to operate both a proton or a deuteron source. To compare these three production routes, an accurate knowledge of the cross-sections is essential. In this paper, we report on the cross-section measurement of the reaction 42 Ca(d,n) 43 Sc performed at the 6 MV HVEC EN-Tandem of the Ion Beam Physics group at ETH in Zürich. A study of the production yield by using commercially available enriched target materials is also presented., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

In this study 129I and 236U concentrations in seawater samples collected onboard R/V Polarstern during the PS100 expedition in the Fram Strait in 2016 are presented. The overall aim of the study was to investigate the distribution of these long‐lived radionuclides along the transect located at 79°N. The combination of both radionuclides was used for the first time in the Fram Strait to trace ocean circulation pathways of Atlantic waters. Results show that both 129I and 236U concentrations as well as 236U/238U ratios are about two times higher (> 600 × 107 at kg(−1), > 20 × 106 at kg(−1), and 2.8 × 10−9, respectively) in the cold and fresh outflowing surface waters from the Arctic Ocean (Polar Surface Water, PSW) compared to inflowing Atlantic origin waters (300 × 107 at kg(−1)129I, 12 × 106 at kg(−1)236U, and 1.4 × 10−9 236U/238U). A comparison with the different 129I and 236U input functions for the Atlantic branches entering the Arctic Ocean reveals that the middepth Atlantic origin waters outflowing the Arctic Ocean show more influence of the Barents Sea Branch Water than the Fram Strait Branch Water. The high radionuclide concentrations observed in the PSW indicate substantial influence of the Norwegian Coastal Current. This current carries a significantly larger proportion of 129I and 236U releases from European reprocessing plants than the aforementioned Atlantic branches. We estimate surface water transit times from the northern Norwegian Coast through the Arctic to the PSW of 12–19 years, less than for the middepth Barents Sea Branch Water (16–23 years). Plain Language Summary: In this work we reconstructed the circulation of Atlantic waters in‐ and outflowing the Arctic Ocean through one of the main gates connecting these two oceans: the Fram Strait, located between Greenland and Svalbard. We measured the long‐lived artificial radionuclides 129I and 236U to track the different water masses. These two radionuclides are present in the marine environment after the nuclear weapon tests (1950s‐1960s) and from two European nuclear reprocessing plants (from 1960's until today). In particular the input of 129I from these two reprocessing plants changed over time and can therefore also be used to estimate travel times of water masses. We collected 140 seawater samples at various depths from the Fram Strait in summer 2016. Our results depict higher concentrations of 129I and 236U in the waters outflowing the Arctic Ocean compared to those entering the polar region through the Fram Strait. The combination of 129I and 236U allowed us to distinguish between three main branches of Atlantic origin waters outflowing the Arctic Ocean having different travel times through the Arctic Ocean. We proved that 129I and 236U have a great potential as tracers to understand ocean circulation and travel times in the Arctic and North Atlantic oceans. Key Points: In 2016, inflowing Atlantic waters to the Arctic Ocean have lower 129I and 236U concentrations than outflowing Arctic watersHigh 129I and 236U in outflowing surface Arctic waters indicate substantial influence from the Norwegian Coastal CurrentCombination of 129I and 236U allowed for an estimation of transit times for Atlantic branches through the Arctic Ocean to the Fram Strait [ABSTRACT FROM AUTHOR]

Abstract: The current performance of all three AMS systems in operation at ETH Zurich, the 6MV HVEC EN-Tandem facility “TANDEM”, the 0.5MV NEC Pelletron “TANDY”, and the 0.2MV system “MICADAS” is summarized. Radionuclides routinely measured with these AMS systems include 10Be, 14C, 26Al, 36Cl, 41Ca, 129I and the actinides. The reference materials used for the normalization of the AMS measurements at the ETH Zurich AMS facilities are presented. This paper therefore is a comprehensive status report of all three AMS systems currently operated by the Laboratory of Ion Beam Physics (LIP) at ETH Zurich and documents their performance and operation parameters. [Copyright &y& Elsevier]

Well-established data on production-rates of long-lived radionuclides are important for the understanding and calculation of various nucleosynthesis processes. However, lack of information exists for a list of nuclides as pointed out by nuclear-data requests. In addition, the search for supernova (SN)-produced radionuclides will give an improved insight into explosive scenarios. Accelerator mass spectrometry (AMS) represents a technique, which is capable to quantify such long-lived radionuclides using mass spectrometric methods. The potential of AMS is presented here as a powerful tool for probing nucleosynthesis. Applications of AMS are exemplified for a few specific cases: the detection of extraterrestrial radioactivity on Earth in terrestrial archives as a signature of nearby SN explosions, and the measurement of cross-sections, as an important ingredient for stellar as well as nuclear model calculations. [ABSTRACT FROM AUTHOR]

Gamma-ray telescopes in orbit around the earth are searching for evidence of the elusive radionuclide 22Na produced in novae. Previously published uncertainties in the dominant destructive reaction, 22Na(p,γ)23Mg, indicated new measurements in the proton energy range of 150 to 300 keV were needed to constrain predictions. We have measured the resonance strengths, energies, and branches directly and absolutely by using protons from the University of Washington accelerator with a specially designed beam line, which included beam rastering and cold vacuum protection of the 22Na implanted targets. The targets, fabricated at TRIUMF-ISAC, displayed minimal degradation over a ~20 C bombardment as a result of protective layers. We avoided the need to know the absolute stopping power, and hence the target composition, by extracting resonance strengths from excitation functions integrated over proton energy. Our measurements revealed that resonance strengths for Ep=213, 288, 454, and 610 keV are stronger by factors of 2.4-3.2 than previously reported. Upper limits have been placed on proposed resonances at 198, 209, and 232 keV. These substantially reduce the uncertainty in the reaction rate. We have re-evaluated the 22Na(p,γ) reaction rate, and our measurements indicate the resonance at 213 keV makes the most significant contribution to 22Na destruction in novae. Hydrodynamic simulations including our rate indicate that the expected abundance of 22Na ejecta from a classical nova is reduced by factors between 1.5 and 2, depending on the mass of the white-dwarf star hosting the nova explosion. [ABSTRACT FROM AUTHOR]

Abstract: The radioisotope 182Hf (t 1/2 =8.9Ma) is of great interest for astrophysical applications as a chronometer for the early solar system or as possible live supernova remnant on earth. However, AMS measurements of 182Hf are seriously influenced by the presence of the stable isobar 182W, which cannot be separated at typical AMS energies. Previous studies revealed a possible suppression of 182W against 182Hf by extracting the negatively charged pentafluoride from the ion source, leading to a detection limit for 182Hf/180Hf in the order of 10−11. However, this suppression behavior is in contrast to theoretical calculations of the electron affinity and recent measurements using SIMS instruments, where the achieved suppression cannot be reproduced. The aim of our study is to determine the effects of ion source background as well as further investigate the suppression of tungsten against hafnium by extracting negatively charged fluoride ions from different sample materials. The previously reported suppression factor of about 6000 could be increased to 36000 by careful tuning of the ion source using HfF4 as sample material. The trend of the theoretical electron affinities could be reproduced using atomic tungsten and hafnium instead of HfF4 as sample material. This supports the assumption that the major contribution of the tungsten background is not sputtered from the target matrix but comes from somewhere else in the ion source. Measurements from the second ion source show a higher background of tungsten and a lower suppression factor, i.e. careful design of the ion source is crucial. Moving the sputter beam over the target surface extending over the wheel holding the targets revealed the highest tungsten background was detected outside the sputter target position. Further investigations are necessary to locate the origin of the tungsten background in the ion source. Possible sources are the material used for the ion source construction or contaminations in the cesium used for sputtering. [Copyright &y& Elsevier]