Efficient Production of High Specific Activity Thulium-167 at Paul Scherrer Institute and CERN-MEDICIS

Thulium-167 is a promising radionuclide for nuclear medicine applications with potential use for both diagnosis and therapy (“theragnostics”) in disseminated tumor cells and small metastases, due to suitable gamma-line as well as conversion/Auger electron energies. However, adequate delivery methods are yet to be developed and accompanying radiobiological effects to be investigated, demanding the availability of 167Tm in appropriate activities and quality. We report herein on the production of radionuclidically pure 167Tm from proton-irradiated natural erbium oxide targets at a cyclotron and subsequent ion beam mass separation at the CERN-MEDICIS facility, with a particular focus on the process efficiency. Development of the mass separation process with studies on stable 169Tm yielded 65 and 60% for pure and erbium-excess samples. An enhancement factor of thulium ion beam over that of erbium of up to several 104 was shown by utilizing laser resonance ionization and exploiting differences in their vapor pressures. Three 167Tm samples produced at the IP2 irradiation station, receiving 22.8 MeV protons from Injector II at Paul Scherrer Institute (PSI), were mass separated with collected radionuclide efficiencies between 11 and 20%. Ion beam sputtering from the collection foils was identified as a limiting factor. In-situ gamma-measurements showed that up to 45% separation efficiency could be fully collected if these limits are overcome. Comparative analyses show possible neighboring mass suppression factors of more than 1,000, and overall 167Tm/Er purity increase in the same range. Both the actual achieved collection and separation efficiencies present the highest values for the mass separation of external radionuclide sources at MEDICIS to date.

The Search for μ+ → e+γ with 10–14 Sensitivity: The Upgrade of the MEG Experiment

The MEG experiment took data at the Paul Scherrer Institute in the years 2009–2013 to test the violation of the lepton flavor conservation law, which originates from an accidental symmetry that the Standard Model of elementary particle physics has, and published the most stringent limit on the charged lepton flavor violating decay μ+→e+γ: BR(μ+→e+γ) <4.2×10−13 at 90% confidence level. The MEG detector has been upgraded in order to reach a sensitivity of 6×10−14. The basic principle of MEG II is to achieve the highest possible sensitivity using the full muon beam intensity at the Paul Scherrer Institute (7×107 muons/s) with an upgraded detector. The main improvements are better rate capability of all sub-detectors and improved resolutions while keeping the same detector concept. In this paper, we present the current status of the preparation, integration and commissioning of the MEG II detector in the recent engineering runs.

Laser Spectroscopy Measurements of Metastable Pionic Helium Atoms at Paul Scherrer Institute

We review recent experiments carried out by the PiHe collaboration of the Paul Scherrer Institute (PSI) that observed an infrared transition of three-body pionic helium atoms by laser spectroscopy. These measurements may lead to a precise determination of the charged pion mass, and complement experiments of antiprotonic helium atoms carried out at the new ELENA facility of CERN.

The Quasi-Liquid Layer on ice observed with NEXAFS

&lt;p&gt;&lt;strong&gt;The Quasi-Liquid Layer on ice observed with NEXAFS&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;&lt;em&gt;Gabathuler, Y. Manoharan, H. Yang, A. Boucly, A. Luca, M. Ammann, T. Bartels-Rausch&lt;/em&gt;&lt;/p&gt;&lt;p&gt;Paul Scherrer Institute, Villigen, Switzerland&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;As temperature approaches the melting point of ice from below, the hydrogen-bonding network at the air &amp;#8211; ice interface evolves from a well-defined hexagonal structure towards more randomly spatialized interactions. The general agreement is that a Quasi-Liquid-Layer (QLL) exists at the surface of the ice, and reports on the thickness of this disordered interfacial layer range from 2 nm to 25 nm at 271 K, depending on the probing technique (atomic force microscopy (AFM), ellipsometry, optical reflectivity, sum-frequency generation (SFG)) [1]. These large differences partly arise from the fact that the different techniques are probing different properties of the interface, and the delicate calibration into the thickness of the QLL contributes greatly to the uncertainty.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;We investigate the QLL using Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy, as Bluhm and his group did in 2002 [2]. The technique probes Auger electrons emitted upon X-ray absorption, thus, NEXAFS becomes inherently sensitive to the upper few nm of the air-ice interfacial region. This work focuses on the probing depth associated with this method and proposes a comprehensive treatment of the data, to help resolve the discrepancy of current thickness data. The importance of the QLL&amp;#8217;s thickness comes from its contribution to environmental science as a reservoir for chemical impurities and as a host of chemical reactions with an impact on atmospheric and cryospheric composition.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;We will present a first data set of NEXAFS from neat ice between &amp;#8211; 40 &amp;#176;C and 0&amp;#176;C acquired at the ISS endstation at the Swiss Light Source of the Paul Scherrer Institute. Results including error bars will be compared to earlier studies. The preliminary analysis suggests that the interfacial disorder seems to be less pronounced than reported in many earlier studies, very much in agreement with recent SFG [3] and AFM data [4].&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;Literature References:&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;Acknowledgment:&lt;/p&gt;&lt;p&gt;We thank A. Laso for technical help, SNF for funding (grant 178962)&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

The Metamorphosis of Radionuclide Production and Development at Paul Scherrer Institute

Radionuclide production and development has a long history at the Paul Scherrer Institute (PSI) and dates back to the founding times of its forerunner institutions: the Federal Institute for Reactor Research and the Swiss Institute for Nuclear Research. The facilities used for this purpose have evolved substantially over the last five decades. Many radiometals in use today, as radiopharmaceuticals, are for the diagnosis and treatment of disease, with the most popular means of detection being Positron Emission Tomography. These positron emitters are easily produced at low proton energies using medical cyclotrons, however, developments at these facilities are lacking. Currently, the fixed 72 MeV proton beam at PSI is degraded at IP2 irradiation station to provide the desired energy to irradiate targets to produce the likes of 44Sc, 43Sc and 64Cu as a proof of principle, which are of great interest to the nuclear medicine community. This development work can then be implemented at facilities containing medical cyclotrons. A history of the development of radionuclides at PSI, along with current development and projects with partner institutions, is described.

The TELL automatic sample changer for macromolecular crystallography

In this paper, the design and functionalities of the high-throughput TELL sample exchange system for macromolecular crystallography is presented. TELL was developed at the Paul Scherrer Institute with a focus on speed, storage capacity and reliability to serve the three macromolecular crystallography beamlines of the Swiss Light Source, as well as the SwissMX instrument at SwissFEL.

Energy Conversion Processes with Perovskite-type Materials

Mixed oxides derived from the perovskite structure by combination of A- and B-site elements and by partial substitution of oxygen provide an immense playground of physico-chemical properties. Here, we give an account of our own research conducted at the Paul Scherrer Institute on perovskite-type oxides and oxynitrides used in electrochemical, photo(electro)chemical and catalytic processes aimed at facing energy relevant issues.

A concept for disposal of highly acidic spent nuclear fuel solutions at PSI

During previous radioanalytical studies at Paul Scherrer Institute ca. 30 L of acidic waste containing spent nuclear fuel was produced, and now they need to be disposed A flow sheet for conditioning of these waste was designed and the extraction chromatography technique is evaluated. Suitable sorbents, such as AMP_PAN, TBP impregnated resin and DGA resin, were selected for the task of Cs-removal, extraction of U and Pu, and extraction of minor actinides and lanthanides, respectively. A pilot device will be built for preliminary tests with simulated solutions, and the facility will be built and evaluated with the real spent fuel solutions.