Soft Gamma Rays from Heavy WIMPs

We propose an explanation of the galactic center gamma ray excess by supersymmetric WIMPs as heavy as 500 GeV. The lightest neutralino annihilates into vector-like leptons or quarks which cascade decay through intermediate Higgs bosons. Due to the long decay chains, the gamma ray spectrum is much softer than naively expected and peaks at GeV energies. The model predicts correlated diboson and dijet signatures to be tested at the LHC.Comment: 8 pages, 8 figures; v2: focus on gamma ray excess, matches published versio

Development and Basic Qualification Steps towards an Electrochemically Based H-Sensor for Lithium System Applications

IFMIF-DONES, or the International Fusion Materials Irradiation Facility-DEMO Oriented Neutron Source, is a facility for investigations into foreseen fusion power plant materials using the relevant neutron irradiation of 14 MeV. This special n-irradiation is generated by the interaction of deuteron beams with liquid lithium. A critical issue during the operation of IFMIF-DONES is the enrichment of dissolved impurities in the Li-melt loops. The danger occurs as a result of hydrogen-induced corrosivity and embrittlement of the loop components, as well as the security hazards associated with the radioactive tritium. Hence, the application of liquid lithium in IFMIF-DONES requires a suitable impurity control system for reliable and low-level maintenance under the operating conditions of DONES. Regarding those requirements, an electrochemical sensor for hydrogen monitoring was developed in the frame of an international EUROFusion–WPENS task, to determine H-concentrations via the electro-motive force (EMF) of Li-melts and a suitable online-monitoring system. Long-term tests demonstrated that the sensor fulfills the requirements of chemical and mechanical stability and functionality under the harsh Li environment under the planned DONES conditions. Obtained results and operational experiences will be discussed in regard to application windows, reproducibility and calibration needs. Additionally, recommendations will be outlined for upgraded systems and future qualification needs

Electrochemical hydrogen detection in DONES loop materials

The radiation-induced degradation of materials in fusion systems is planned to be investigated in IFMIF-DONES (International Fusion Materials Irradiation Facility - DEMO Oriented NEutron Source), where fast neutrons are produced by a reaction of deuteron-beams with a liquid lithium target. A by-product as critical impurity is hydrogen, which might affect the reliable and safe operation of the IFMIF-DONES loops. Therefore, an important issue is the measurement and control of the hydrogen impurity concentrations in liquid lithium. Initially, a practically applicable direct measurement of hydrogen concentrations in lithium facilities did not exist. However, one promising approach to manage this issue is based on the electrochemistry of the DONES materials The developed Electro-Chemical Hydrogen Sensor for Liquid Lithium (ECHSLL) allows the measurement of the electromotive Force (EMF) between a reference materials system and the loop lithium melt, and thus the monitoring of the hydrogen impurity concentrations. This article will show backgrounds of non-metallic impurities in liquid metal materials and the specific material stabilities within DONES. Liquid lithium is a very reactive material. Therefore critical issuesareviable materials compatibilities, the interactions with hydrogen and the transport behaviour of H-ions in electrolytes at the applied temperatures. Further issues are also the syntheses of the electrochemical materials, as hydrogen conducting electrolytes, reference electrode systems and the different procedures (heat treatments and conditioning steps). The tests showed the functionality of the developed H-sensor. Beyond that, the used material combinations exhibited reliable behaviour in melts under harsh conditions. Hence, the most critical aspect (stability of the sensor materials in the Li-melt) has been resolved by using niobium sensor heads. The observed experimental EMF potentials are in good accordance compared with calculated models, also in long-time experiments

Sarrazin

Debatte um die Thesen von Sarrazin.Debate about Sarrazin\u27s book

Long-term corrosion behavior of Al-based coatings in flowing Pb–15.7Li, produced by electrochemical ECX process

RAFM-steels such as Eurofer are considered as structural materials for breeding blankets in future fusion power plants (DEMO). Some of these blankets e.g. HCLL, WCLL and DCLL, use flowing Pb–15.7Li as liquid breeding material. In these concepts, the breeding material will be in direct contact to the structural material at operational temperatures of up to 550 °C. However, bare RAFM steels suffer from strong corrosion attack with corrosion rates between 100 and 400 µm under these conditions. To protect bare RAFM steels from corrosion, Al-based coatings are considered as corrosion barriers. Different coating processes were developed in the past, with focus on electrochemical processes within the last decade. The currently most promising one is the so-called ECX process. Based on the electrodeposition of aluminum from an ionic liquid, it produces smooth and uniform Al enriched scales. These ECX coatings have already shown good short- to mid-term corrosion resistance in flowing Pb–15.7Li for up to 4000 h. In the current study, the long-term corrosion behavior of aluminum-based coatings on Eurofer made by ECX process was investigated. Exposure times of up to 10,000 h in flowing Pb–15.7Li were reached under fusion relevant conditions, i.e. 550 °C and a flow velocity of 0.1 m/s. In comparison to bare Eurofer the corrosion attack is drastically reduced while corrosion rates lay below 20 µm/a. Additionally, it was found that the corrosion behavior is also superior to the corrosion behavior of Al-based barriers produced by the ECA process after long-term exposure in Pb–15.7Li