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The number (n) and diameter (d) of superheated droplets in bubble detectors of Type T-12 have been determined with high-energy heavy ions 56Fe, 84Kr and 132Xe at HIMAC accelerator in the National Institute of Radiological Sciences (NIRS), Chiba Japan. The approach to determining the number and diameter of superheated droplets is based on determination of (1) the average gap distance (g) between two neighboring bubbles in a track of high-energy heavy ion and (2) the volume ratio (VL/V) of superheated droplets to the whole volume of the detector. The volume ratio is known from preparation process of bubble detectors. The average gap distance can be obtained from the mean of gap distances measured between two neighboring bubbles in a track of heavy ion. From g and VL/V one can obtain the two basic parameters n and d of the bubble detector, which are unknown due to invisibility of superheated droplets in bubble detector. Four batches of bubble detectors of Type T-12 were calibrated by this approach. It shows that the average gap distance of bubbles in the detectors is ∼1 mm, the volume density (number n) of superheated droplets in the detectors is ∼106 cm−3 and the diameter of superheated droplets is in the range from ∼30 to 50 μm. It also shows that the two parameters n and d are different from batch to batch of the detectors when VL/V is the same. Therefore, one should make a calibration of bubble detectors at accelerator with heavy ions before using the detectors. This property is similar to that of etch track detectors (SSNTD). Keywords: Bubble detector, Number of superheated droplets, Diameter of superheated droplets, Gap distance between two neighboring bubbles in a track, Calibration of bubble detectors with heavy ions at accelerator, Grubbs criteria for rejecting parasitic erroneous data

We report a novel cavity feedback mechanism for stabilizing single-longitudinal-mode (SLM) operation of diamond Raman lasers. Polarization-dependent Raman gain and in-grown stress birefringence in diamond were investigated as sources for Hansch-Couillaud-type locking signals. The power range of SLM operation increased from 2.1 W to 7.2 W, compared to the free-running laser, for a simple standing-wave laser cavity without frequency-selective elements. Methods for further increasing power range and frequency stability are discussed.

In this work we study the effect of laser conditioning on laser-induced damage of ion-beam sputtered, anti-reflection coated laser optics with ns-pulsed laser radiation at a wavelength of 355 nm. With respect to applications in aerospace, measurements were performed under high vacuum. At laser fluences below 20 J/cm2, laser-induced damage appears as pin-point damage (small explosion pits with sizes in the range of 1 micro-meter), sometimes referred to as "grey haze". We find that ramped laser conditioning is an effective tool to reduce not only the abundance but also the average size of pin-point damage at laser fluences exceeding the optic’s unconditioned laser-induced damage threshold. We discuss our results in the context of the small absorber model for damage crater formation.

International audience; A new contactless technique is presented for the detection of micron-sized insulating particles in the flow of an electrically conducting fluid. A transverse magnetic field brakes this flow and tends to become entrained in the flow direction by a Lorentz force, whose reaction force on the magnetic-field-generating system can be measured. The presence of insulating particles suspended in the fluid produce changes in this Lorentz force, generating pulses in it; these pulses enable the particles to be counted and sized. A two-dimensional numerical model that employs a moving mesh method demonstrates the measurement principle when such a particle is present. Two prototypes and a three-dimensional numerical model are used to demonstrate the feasibility of a Lorentz force particle analyzer (LFPA). The findings of this study conclude that such an LFPA, which offers contactless and on-line quantitative measurements, can be applied to an extensive range of applications. These applications include measurements of the cleanliness of high-temperature and aggressive molten metal, such as aluminum and steel alloys, and the clean manufacturing of semiconductors. Published by AIP Publishing.

Field exposition experiments have been initiated by the German Federal Office for Radiation Protection (Bundesamt für Strahlenschutz – BfS) to examine genotoxic effects of THz radiation in vitro. Two different human skin cell types are exposed to continuous-wave radiation at six distinct frequencies between 100 GHz and 2.52 THz originating from different sources of THz radiation under defined environmental conditions. The cell containers are irradiated with free space power flux densities between 0.1 mW/cm2 and 2 mW/cm2 measured traceable to the SI units. For meaningful results, dosimetric calculations using the finite differences time-domain method have been performed in order to access the fields and consequently the specific absorption rate (SAR) in the cell layer.

In order to investigate the complex relative dielectric constant of different materials over a frequency range of 50 MHz to 3 GHz a setup has been built that allows rf-measurements in a climate chamber. Within this chamber the temperature and humidity can be changed and be measured by accurate sensors. The construction of the rf-part of the setup has been made with an outer cylindrical shell that allows climate interactions through its large orifices. Methods for calculating the complex relative dielectric constant from the measured scattering parameters are presented and the changes of the relative constants due to different humidity conditions are shown.

A conceptual framework to predict microphysical and optical properties of contrail particles within a wingspan behind the source aircraft is developed. Results from two decades of contrail observations and numerical simulations are reviewed forming the basis of theoretical model development. The model utilizes cloud theory applied to the dynamics and thermodynamics of jet aircraft exhaust plumes in upper tropospheric conditions. Droplet nuclei include soot particles emitted from aircraft engines and atmospheric particles entrained into the plume. These precursor particles activate into copious homogeneously freezing water droplets as the plume relative humidity rises beyond liquid water saturation. A unimodal size spectrum of ice particles develops wherein ice particles grow to micrometer mean sizes. Contrail particle formation is analyzed over a wide range of soot emissions relating to conventional jet fuels as well as to alternative aviation fuels producing much less soot and volatile particle emissions. For current aviation fuels and propulsion technology, the number of contrail ice particles scales roughly in proportion to the number of emitted soot particles that act as water condensation nuclei despite their poor hygroscopicity. Close to the contrail formation threshold, only few plume particles can be water activated and freeze. Implications for effects of alternative fuels on contrails, an arena for future scientific exploration, are outlined.

Nanoscale inhomogeneities and impurity clustering are often found to drastically affect the magnetic and transport properties in disordered/diluted systems, giving rise to rich and complex phenomena. However, the physics of these systems still remains to be explored in more details as can be seen from the scarce literature available. We present a detailed theoretical analysis of the effects of nanoscale inhomogeneities on the spin excitation spectrum in diluted magnetic systems. The calculations are performed on relatively large systems (up to $N$=$66^3$). It is found that even low concentrations of inhomogeneities have drastic effects on both the magnon density of states and magnon excitations. These effects become even more pronounced in the case of short ranged magnetic interactions between the impurities. In contrast to the increase of critical temperatures $T_C$, reported in previous studies, the spin-stiffness $D$ is systematically suppressed in the presence of nanoscale inhomogeneities. Moreover $D$ is found to strongly depend on the inhomogeneities' concentration, the cluster size, as well as the range of the magnetic interactions. The findings are discussed in the prospect of potential spintronics applications. We believe that this detailed numerical work could initiate future experimental studies to probe this rich physics with the most appropriate tool, Inelastic Neutron Scattering (INS)., One new figure added, text revised and some figures modified to match the published version

Fur die EUV-Lithographie, die als aussichtsreichstes Verfahren fur die Herstellung von Halbleiterstrukturen unterhalb von 50 nm gilt, kommen reflektierende Multischichten als optische Elemente zum Einsatz. Diese mussen eine moglichst hohe Reflektivitat aufweisen, da diese die Effizienz des Verfahrens und damit den Durchsatz einer zukunftigen Chip-Fabrik masgeblich bestimmt. In dieser Arbeit werden Untersuchungen zur Grenzflachenbeschaffenheit von Mo/Si Multischichten, die mittels Magnetron Sputter Deposition hergestellt wurden, vorgestellt. Ausgehend vom zweikomponentigen Mo/Si-System, bei dem vorrangig der Einfluss der Abscheidebedingungen auf die Grenzflachenrauhigkeit betrachtet wird, gelang es, durch den Einbau von dunnsten Barriereschichten auch die Grenzflacheninterdiffusion zu reduzieren. Im reinen Mo/Si System ist vor allem ein niedriger Ar-Sputtergasdruck wichtig, um glatte Grenzflachen zu erzeugen. Die Verringerung der Interdiffusion der Mo- und Si-Atome kann durch den Einbau von C- und B4C-Barriereschichten geeigneter Dicke erreicht werden. Als Ergebnis der Untersuchungen wurden Mo/Si Multischichten mit momentan den weltweit hochsten EUV-Reflektivitaten prapariert: REUV = 70.1 % (λ = 13.3 nm, α = 1.5°), REUV = 71.4 % (λ = 12.5 nm, α = 22.5°). EUV lithography is the most promising technique for the fabrication of semiconductor structures below 50 nm. This requires the use of reflecting multilayers as optical elements. These multilayers must have reflectances as high as possible since it determines the efficiency of the technique and therefore the throughput of a future chip fab. In this work we present investigations on the interface quality of Mo/Si multilayers which are prepared by magnetron sputter deposition. Starting from the two-component Mo/Si system, that has mainly been optimized with respect to interface roughness, we show that interface interdiffusion can also be reduced by the introduction of tiny barrier layers. In pure Mo/Si multilayers particularly a low Ar sputter gas pressure is important to get smooth layers, whereas the interdiffusion can be reduced by the deposition of C and B4C barrier layers on the individual interfaces. As result of our work, we have prepared Mo/Si multilayers with outstanding high reflectances: REUV = 70.1 % (λ = 13.3 nm, α = 1.5°), REUV = 71.4 % (λ = 12.5 nm, α = 22.5°).

A quantitative study of the long-range interaction between single copper adatoms on Cu(111) mediated by the electrons in the two-dimensional surface-state band is presented. The interaction potential was determined by evaluating the distance distribution of two adatoms from a series of scanning tunneling microscopy images taken at temperatures of 9-21 K. The long-range interaction is oscillatory with a period of half the Fermi wavelength and decays for larger distances d as 1/d(2). Five potential minima were identified for separations of up to 70 A. The interaction significantly changes the growth of Cu/Cu(111) at low temperatures.

The ionisation of deep impurity centres in germanium has been observed with radiation in the terahertz range where the photon energy is much less than the binding energy of the impurities. It is shown that for not too high radiation intensities the ionisation is caused by the Poole-Frenkel effect. As in the well-known case of d.c. fields, the electric field of the high-frequency radiation lowers the Coulomb potential barrier and enhances the thermal emission of carriers.