Experimental evidence of planar channeling in a periodically bent crystal

The usage of a Crystalline Undulator (CU) has been identified as a promising solution for generating powerful and monochromatic $\gamma$-rays. A CU was fabricated at SSL through the grooving method, i.e., by the manufacturing of a series of periodical grooves on the major surfaces of a crystal. The CU was extensively characterized both morphologically via optical interferometry at SSL and structurally via X-ray diffraction at ESRF. Then, it was finally tested for channeling with a 400 GeV/c proton beam at CERN. The experimental results were compared to Monte Carlo simulations. Evidence of planar channeling in the CU was firmly observed. Finally, the emission spectrum of the positron beam interacting with the CU was simulated for possible usage in currently existing facilities

A strained silicon cold electron bolometer using Schottky contacts

We describe optical characterisation of a strained silicon cold electron bolometer (CEB), operating on a 350 mK stage, designed for absorption of millimetre-wave radiation. The silicon cold electron bolometer utilises Schottky contacts between a superconductor and an n++ doped silicon island to detect changes in the temperature of the charge carriers in the silicon, due to variations in absorbed radiation. By using strained silicon as the absorber, we decrease the electron-phonon coupling in the device and increase the responsivity to incoming power. The strained silicon absorber is coupled to a planar aluminium twin-slot antenna designed to couple to 160 GHz and that serves as the superconducting contacts. From the measured optical responsivity and spectral response, we calculate a maximum optical efficiency of 50% for radiation coupled into the device by the planar antenna and an overall noise equivalent power, referred to absorbed optical power, of 1.1×10−16 W Hz−1/2 when the detector is observing a 300 K source through a 4 K throughput limiting aperture. Even though this optical system is not optimized, we measure a system noise equivalent temperature difference of 6 mK Hz−1/2. We measure the noise of the device using a cross-correlation of time stream data, measured simultaneously with two junction field-effect transistor amplifiers, with a base correlated noise level of 300 pV Hz−1/2 and find that the total noise is consistent with a combination of photon noise, current shot noise, and electron-phonon thermal noise

Effective mobilities in pseudomorphic Si/SiGe/Si p-channel metal-oxide-semiconductor field-effect transistors with thin silicon capping layers

The room-temperature effective mobilities of pseudomorphic Si/Si0.64Ge0.36/Si p-metal-oxidesemiconductor field effect transistors are reported. The peak mobility in the buried SiGe channel increases with silicon cap thickness. It is argued that SiO2/Si interface roughness is a major source of scattering in these devices, which is attenuated for thicker silicon caps. It is also suggested that segregated Ge in the silicon cap interferes with the oxidation process, leading to increased SiO2/Si interface roughness in the case of thin silicon caps

A consensus building exercise to determine research priorities for silver trauma

Background Emergency care research into ‘Silver Trauma’, which is simply defined as major trauma consequent upon relatively minor injury mechanisms, is facing many challenges including that at present, there is no clear prioritisation of the issues. This study aimed to determine the top research priorities to guide future research. Methods This consensus-based prioritization exercise used a three-stage modified Delphi technique. The study consisted of an idea generating (divergent) first round, a ranking evaluation in the second round, and a (convergent) consensus meeting in the third round. Results A total of 20 research questions advanced to the final round of this study. After discussing the importance and clinical significance of each research question, five research questions were prioritised by the experts; the top three research priorities were: (1). What are older people’s preferred goals of trauma care? (2). Beyond the Emergency Department (ED), what is the appropriate combined geriatric and trauma care? (3). Do older adults benefit from access to trauma centres? If so, do older trauma patients have equitable access to trauma centre compared to younger adults? Conclusion The results of this study will assist clinicians, researchers, and organisations that are interested in silver trauma in guiding their future efforts and funding toward addressing the identified research priorities

Torsion pairs and rigid objects in tubes

We classify the torsion pairs in a tube category and show that they are in bijection with maximal rigid objects in the extension of the tube category containing the Pruefer and adic modules. We show that the annulus geometric model for the tube category can be extended to the larger category and interpret torsion pairs, maximal rigid objects and the bijection between them geometrically. We also give a similar geometric description in the case of the linear orientation of a Dynkin quiver of type A.Comment: 25 pages, 13 figures. Paper shortened. Minor errors correcte

The Microcalorimeter Arrays for a Rhenium Experiment (MARE): a next-generation calorimetric neutrino mass experiment

Neutrino oscillation experiments have proved that neutrinos are massive particles, but can't determine their absolute mass scale. Therefore the neutrino mass is still an open question in elementary particle physics. An international collaboration is growing around the project of Microcalorimeter Arrays for a Rhenium Experiment (MARE) for directly measuring the neutrino mass with a sensitivity of about 0.2eV/c2. Many groups are joining their experiences and technical expertise in a common effort towards this challenging experiment. We discuss the different scenarios and the impact of MARE as a complement of KATRIN.Comment: 3 pages, 1 figure Nucl. Instr. Meth. A, proceedings of LTD11 workshop, Tokyo 200

A narrow band neutrino beam with high precision flux measurements

The ENUBET facility is a proposed narrow band neutrino beam where lepton production is monitored at single particle level in the instrumented decay tunnel. This facility addresses simultaneously the two most important challenges for the next generation of cross section experiments: a superior control of the flux and flavor composition at source and a high level of tunability and precision in the selection of the energy of the outcoming neutrinos. We report here the latest results in the development and test of the instrumentation for the decay tunnel. Special emphasis is given to irradiation tests of the photo-sensors performed at INFN-LNL and CERN in 2017 and to the first application of polysiloxane-based scintillators in high energy physics.Comment: Poster presented at NuPhys2017 (London, 20-22 December 2017). 5 pages, 2 figure

Interfacial engineering of semiconductor–superconductor junctions for high performance micro-coolers

The control of electronic and thermal transport through material interfaces is crucial for numerous micro and nanoelectronics applications and quantum devices. Here we report on the engineering of the electro-thermal properties of semiconductor-superconductor (Sm-S) electronic cooler junctions by a nanoscale insulating tunnel barrier introduced between the Sm and S electrodes. Unexpectedly, such an interface barrier does not increase the junction resistance but strongly reduces the detrimental sub-gap leakage current. These features are key to achieving high cooling power tunnel junction refrigerators, and we demonstrate unparalleled performance in silicon-based Sm-S electron cooler devices with orders of magnitudes improvement in the cooling power in comparison to previous works. By adapting the junctions in strain-engineered silicon coolers we also demonstrate efficient electron temperature reduction from 300 mK to below 100 mK. Investigations on junctions with different interface quality indicate that the previously unexplained sub-gap leakage current is strongly influenced by the Sm-S interface states. These states often dictate the junction electrical resistance through the well-known Fermi level pinning effect and, therefore, superconductivity could be generally used to probe and optimize metal-semiconductor contact behaviour