A compact design for beam transport

A double-achromatic, double-focusing magnet system of very small size is described which will be used in the injection line for an undulator in a FEL experiment. Because of the double focusing no quadrupoles are needed between the dipole, which couples the electrons in the FEL cavity, and the undulator. An example will be worked out for an electron bunch of 25 MeV, 100 A which is focused on a spot of 1 mm diameter

Electronic orders near the type-II van Hove singularity in BC3_3

Using the functional renormalization group, we investigate the electron instability in the single-sheet BC$_3$ when the electron filling is near a type-II van Hove singularity. For a finite Hubbard interaction, the ferromagnetic-like spin density wave order dominates in the immediate vicinity of the singularity. Elsewhere near the singularity the p-wave superconductivity prevails. We also find that a small nearest-neighbor Coulomb repulsion can enhance the superconductivity. Our results show that BC$_3$ would be a promising candidate to realize topological $p+ip'$ superconductivity, but the transition temperature is practically sizable only if the local interaction is moderately strong.Comment: 6 pages, 6 color figures. arXiv admin note: text overlap with arXiv:1503.0047

Location of Investors and Capital Flight

This paper utilizes a very simple model to study the timing and determinants of speculationagainst a fixed exchange rate regime when investors are heterogeneous because of locationaldifferences. Location matters because resident players may incur smaller costs when takinga short-position, are less exposed to exchange rate risk, possess better information quality,have more knowledge about each others information sets, due to asymmetries in tax treatment,or because of the presence of government guarantees. Our model clarifies the respective rolesplayed by local and international investors during episodes of capital flight as well as theresulting room of maneuver for policymakers in emerging markets

Magnetotransport properties of iron microwires fabricated by focused electron beam induced autocatalytic growth

We have prepared iron microwires in a combination of focused electron beam induced deposition (FEBID) and autocatalytic growth from the iron pentacarbonyl, Fe(CO)5, precursor gas under UHV conditions. The electrical transport properties of the microwires were investigated and it was found that the temperature dependence of the longitudinal resistivity (rhoxx) shows a typical metallic behaviour with a room temperature value of about 88 micro{\Omega} cm. In order to investigate the magnetotransport properties we have measured the isothermal Hall-resistivities in the range between 4.2 K and 260 K. From these measurements positive values for the ordinary and the anomalous Hall coefficients were derived. The relation between anomalous Hall resistivity (rhoAN) and longitudinal resistivity is quadratic, rhoAN rho^2 xx, revealing an intrinsic origin of the anomalous Hall effect. Finally, at low temperature in the transversal geometry a negative magnetoresistance of about 0.2 % was measured

Zero slippage operation of TEUFEL

The Free Electron Laser in Twente TEUFEL is very suitable to operate near zero slippage conditions. The resonator is a waveguide structure with hole coupling for the electron beam to enter and exit and to out-couple the light. Due to the long wavelength, the diameter of the waveguide can have macroscopic dimensions to significantly affect the group velocity of the generated light via the dispersion relation. Whereas the longitudinal phase-velocity has to be equal to the longitudinal velocity of the electrons to be at resonance, the longitudinal group velocity has to be equal the longitudinal velocity of the electrons too, to operate in the zeroslippage regime. Both conditions can be fulfilled in a waveguide. Advantage of operation in the zero-slippage regime is to allow short pulse operation at high gain. The energy density of the light travels with the electron pulse. For our FEL we expect operation with the following parameters: Electron energy 4 MeV; diameter of circular waveguide 3.2 mm; generated wavelength 658 mm; pulse duration 25 ps. Due to the high quality beam, i.e. high current and low emittance we expect high gain

Towards a single step process to create high purity gold structures by electron beam induced deposition at room temperature

Highly pure metallic structures can be deposited by electron beam induced deposition and they have many important applications in different fields. The organo-metallic precursor is decomposed and deposited under the electron beam, and typically it is purified with post-irradiation in presence of O2. However, this approach limits the purification to the surface of the deposit. Therefore, 'in situ' purification during deposition using simultaneous flows of both O2 and precursor in parallel with two gas injector needles has been tested and verified. To simplify the practical arrangements, a special concentric nozzle has been designed allowing deposition and purification performed together in a single step. With this new device metallic structures with high purity can be obtained more easily, while there is no limit on the height of the structures within a practical time frame. In this work, we summarize the first results obtained for 'in situ' Au purification using this concentric nozzle, which is described in more detail, including flow simulations. The operational parameter space is explored in order to optimize the shape as well as the purity of the deposits, which are evaluated through scanning electron microscope and energy dispersive x-ray spectroscopy measurements, respectively. The observed variations are interpreted in relation to other variables, such as the deposition yield. The resistivity of purified lines is also measured, and the influence of additional post treatments as a last purification step is studied.EMPA is acknowledged for providing the original code for the GIS simulator model, which was extended by Stan de Muijnck (TU Delft) with the new geometry. Pleun Dona (FEI) is acknowledged for helping in the design of the concentric nozzle and in getting a working prototype. Patricia Peinado is also acknowledged for help on experimental activities. This work was supported by NanoNextNL program, a Dutch national research and technology program for micro- and nano-technology

Diversity at the Ballot Box: Electoral Politics and Maine\u27s Minority Communities, Post-WWII to the Present

As this year’s Sampson Center exhibition makes clear the powerful desire to find historical inevitability in the advance toward equal opportunity for all Americans has become far more nuanced by the sometimes discomforting reminders that advances at the ballot box are neither as clear-cut nor as unconditional as we once hoped. The ancient antipathies of racism, anti-Semitism, and homophobia are not so easily elided by political campaigns and elections. The pace of social consensus requires a degree of patience and continuing attention that tries the very fabric of American life while we attempt to comprehend the consequences of change wrought by our heightened understanding of the implications of diversity in American life. Table of Contents: Introduction (Selma Botman, USM President) Quiet Revolution: A Tally of Black Victories (Bob Greene, for the African American Collection) Is It Good for the Jews? Is it Good for Everyone? Maine Jewry between Civic Idealism and the Politics of Reality (Abraham J. Peck, Scholar-in-Residence for the Judaica Collection) From the Closet to the Ballot-Box: Electoral Politics and Maine’s LGBT Citizens, 1970s to the Present (Howard M. Solomon, Scholar-in-Residence for the Lesbian, Gay, Bisexual, and Transgender Collection)https://digitalcommons.usm.maine.edu/event_catalog/1003/thumbnail.jp

Explaining Africa’s public consumption procyclicality : revisiting old evidence

This paper compiles a novel dataset of time-varying measures of government consumption cyclicality for a panel of 46 African economies between 1960 and 2014. Government consumption has, generally, been highly procyclical over time in this group of countries. However, sample averages hide serious heterogeneity across countries with the majority of them showing procyclical behavior despite some positive signs of graduation from the “procyclicality trap” in a few cases. By means of weighted least squares regressions, we find that more developed African economies tend to have a smaller degree of government consumption procyclicality. Countries with higher social fragmentation and those are more reliant on foreign aid inflows tend to have a more procyclical government consumption policy. Better governance promotes counter- cyclical fiscal policy whileincreased democracy dampens it. Finally, some fiscal rules are important in curbing the procyclical behavior of government consumption.info:eu-repo/semantics/publishedVersio