Photodisintegration of aligned deuterons at astrophysical energies using linearly polarized photons

Following the model independent approach to deuteron photodisintegration with linearly polarized $\gamma-$rays, we show that the measurements of the tensor analyzing powers on aligned deuterons along with the differential cross section involve five different linear combinations of the isovector $E1^j_v; j=0,1,2$ amplitudes interfering with the isoscalar $M1_s$ and $E2_s$ amplitudes. This is of current interest in view of the recent experimental finding \cite{blackston1} that the three $E1^j_v$ amplitudes are distinct and also the reported experimental observation \cite{sawatzky} on the front-back (polar angle) asymmetry in the differential cross section.Comment: 12 page

Bunching instability of rotating relativistic electron layers and coherent synchrotron radiation

We study the stability of a collisionless, relativistic, finite-strength, cylindrical layer of charged particles in free space by solving the linearized Vlasov-Maxwell equations and compute the power of the emitted electromagnetic waves. The layer is rotating in an external magnetic field parallel to the layer. This system is of interest to understanding the high brightness temperature of pulsars which cannot be explained by an incoherent radiation mechanism. Coherent synchrotron radiation has also been observed recently in bunch compressors used in particle accelerators. We consider equilibrium layers with a `thermal' energy spread and therefore a non-zero radial thickness. The particles interact with their retarded electromagnetic self-fields. The effect of the betatron oscillations is retained. A short azimuthal wavelength instability is found which causes a modulation of the charge and current densities. The growth rate is found to be an increasing function of the azimuthal wavenumber, a decreasing function of the Lorentz factor, and proportional to the square root of the total number of electrons. We argue that the growth of the unstable perturbation saturates when the trapping frequency of electrons in the wave becomes comparable to the growth rate. Owing to this saturation we can predict the radiation spectrum for a given set of parameters. Our predicted brightness temperatures are proportional to the square of the number of particles and scale by the inverse five-third power of the azimuthal wavenumber which is in rough accord with the observed spectra of radio pulsars.Comment: 15 pages, 9 figures, LaTeX; presented at the April Meeting in Denver, Colorado 2004; numerous typos corrected, one approximation removed, one new proof added, accepted for publication in Phys. Rev.

TEMPORARY TENSILE STRENGTH OF WELDED STRUCTURES MADE FROM DOMESTIC AND FOREIGN MATERIALS

When welding domestic and imported alloys with argonarc welding, unexplored material properties are formed in the weld, there is no information about the mechanical properties of welded joints, their continuity and uniformity. One of the most important criteria for working capacity of any construction is a strength of the whole structure and its individual elements. As a comparative characteristics that evaluates the strength of the materials we use tensile strength, that is, the tension corresponding to the greatest efforts preceding the rupture of the sample under static mechanical tests. Tests to identify the ultimate tensile strength of sheet welded joints were carried out on a universal testing machine Inspekt-50. In the course of studies there was defined tensile strength of welded constructions, obtained by fusing domestic and imported sheet hire materials. Tensile strength of the welded structure is determined by the characteristics of the least durable material in a pair of connected, which corresponds to conclusions made in the analytical review. When testing it was observed that the destruction of all samples made of combination of dissimilar materials occurred at the base of the weakest metal in the combination. The destruction of the weld was not fixed. The results obtained can be used in the design of welded constructions composed of parts made of domestic and imported materials. However, it is impossible to judge the working capacity of welded pipes of integrated air conditioning and anti-icing aircraft systems by tensile strength only. Subsequently, it is necessary to carry out tests on low-cycle fatigue and assess the strength of the welded ring joints under the action of static and pulsating internal pressure

Sensitive Spectroscopic Analysis of Biomarkers in Exhaled Breath

19th International Conference on Photoacoustic and Photothermal Phenomena (ICPPP) -- JUL 16-20, 2017 -- Bilbao, SPAINKaya, Necati/0000-0001-9461-7623WOS: 000431762900001We have developed a novel optical setup which is based on a high finesse cavity and absorption laser spectroscopy in the near-IR spectral region. In pilot experiments, spectrally resolved absorption measurements of biomarkers in exhaled breath, such as methane and acetone, were carried out using cavity ring-down spectroscopy (CRDS). With a 172-cm-long cavity, an efficient optical path of similar to 132 km was achieved. The CRDS technique is well suited for such measurements due to its high sensitivity and good spectral resolution. The detection limits for methane of similar to 8 ppbv and acetone of similar to 2.1 ppbv with spectral sampling of 0.005 cm(-1) were achieved, which allowed to analyze multicomponent gas mixtures and to observe absorption peaks of (CH4)-C-12 and (CH4)-C-13. Further improvements of the technique have the potential to realize diagnostics of health conditions based on a multicomponent analysis of breath samples.Robert A. Welch FoundationThe Welch Foundation [A1546]; Qatar Foundation [NPRP 8-735-1-154]; Turkish Ministry of EducationTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK); Higher Committee for Educational Development in Iraq (HCED)This work was supported by the Robert A. Welch Foundation Grant No. A1546 and the Qatar Foundation under the Grant NPRP 8-735-1-154. AB thanks for the support of the Turkish Ministry of Education, and EA thanks for the support of the Higher Committee for Educational Development in Iraq (HCED)