A high resolution spectroscopic study of the oxygen molecule

A high resolution spectrometer which incorporates a narrow line width tunable dye laser was used to make absorption profiles of 57 spectral lines in the Oxygen A-Band at pressures up to one atmosphere in pure O2. The observed line profiles are compared to the Voigt, and a collisionally narrowed, profile using a least squares fitting procedure. The collisionally narrowed profile compares more favorable to the observed profiles. Values of the line strengths and self broadening coeffiencients, determined from the least square fitting process, are presented in tabular form. It is found that the experssion by Watson are in closest agreement with the experimentally determined strengths. The self broadening coefficients are compared with the measurements of several other investigators

Free-Knot Spline Approximation of Stochastic Processes

We study optimal approximation of stochastic processes by polynomial splines with free knots. The number of free knots is either a priori fixed or may depend on the particular trajectory. For the $s$-fold integrated Wiener process as well as for scalar diffusion processes we determine the asymptotic behavior of the average $L_p$-distance to the splines spaces, as the (expected) number $k$ of free knots tends to infinity.Comment: 23 page

Strength, Width, and Pressure Shift Measurements of 54 Lines in the Oxygen A-Band

The absorption band of molecular oxygen, centered at 760]en1] nm, is the atmospheric absorber for the Differential Absorption Lidar (DIAL) systems used to measure atmospheric temperature, pressure, and density. To provide accurate line parameters for such systems, a careful spectroscopic study was made of the A-band, with measurements of line strengths, widths, pressure-induced frequency shifts, and collisional narrowing effects. The width and shift parameters were measured over a temperature range of -20 to 100 C so that the temperature dependence of these parameters can also be determined. To analyze the results, a least-squares fiting routine was written to fit standard line profiles to the observed profiles. These measurements, which include the first observations of pressure shifts and collisional narrowing in the band, are an important contribution to lidar system utilizing the A-band

An annular lithium-drifted germanium detector for studying nuclear reaction gamma-rays

Fabrication and development of annular lithium drifted germanium detector for studying nuclear reaction gamma ray

Observation of long range magnetic ordering in pyrohafnate Nd2Hf2O7: A neutron diffraction study

We have investigated the physical properties of a pyrochlore hafnate Nd2Hf2O7 using ac magnetic susceptibility \chi_ac(T), dc magnetic susceptibility \chi(T), isothermal magnetization M(H) and heat capacity C_p(T) measurements, and determined the magnetic ground state by neutron powder diffraction study. An upturn is observed below 6 K in C_p(T)/T, however both C_p(T) and \chi(T) do not show any clear anomaly down to 2 K. The \chi_ac(T) shows a well pronounced anomaly indicating an antiferromagnetic transition at T_N = 0.55 K. The long range antiferromagnetic ordering is confirmed by neutron diffraction. The refinement of neutron diffraction pattern reveals an all-in/all-out antiferromagnetic structure, where for successive tetrahedra, the four Nd3+ magnetic moments point alternatively all-into or all-out-of the tetrahedron, with an ordering wavevector k = (0, 0, 0) and an ordered state magnetic moment of m = 0.62(1) \mu_B/Nd at 0.1 K. The ordered moment is strongly reduced reflecting strong quantum fluctuations in ordered state.Comment: 10 pages, 9 figures and 2 tables; to appear in Phys. Rev.

Stress transfer and Quaternary faulting in the northern Alpine foreland

Within the SPP Mountain Building Processes in Four Dimensions (MB-4D) we studied postglacial and present seismic rupturing in the northern Alpine Foreland to better understand the impact and forces of mountain building. We started a seismological field experiment to densify the permanent monitoring networks and the AlpArray Seismic Network. The later was also supported as well as its predecessor UNIBRA (Hetényi et al., 2018; Schlömer et al., 2022). Our StressTransfer network consisted of five recording stations in the Upper Rhine Graben, five in the Molasse Basin and five around the Albstadt Shear Zone (Mader et al., 2021a). The latter are still operating due to the increased seismicity during the last years below the western Swabian Alb. We determined local minimum 1-D seismic velocity models to relocate known events in the study regions (Mader et al., 2021b). Waveform cross-correlation was done to detect hitherto unknown events and recover earthquake sequences around the Albstadt Shear Zone (Mader et al., subm.). To determine fault planes and rupture mechanisms we used relative event locations (hypoDD) and FOCMEC for fault plane solutions. For the Albstadt Shear Zone (ASZ), an NNE–SSW striking left-lateral strike-slip rupture zone, we determined a direction of the maximum horizontal stress (SHmax) of 140°–149°. Down to ca. 7–8 km depth, SHmax is bigger than SV (vertical stress); below this depth, SV is the main stress component. Beneath the shallow Hohenzollerngraben (ca. 2-3 km depth), which is nearly perpendicular to the ASZ, we found an NW-SE striking dextral strike-slip fault zone with very weak micro-seismicity in 11-15 km depth (Figure 1). This zone is possibly a reactivated old upper-crustal tectonic structure. At the interception of the ASZ and the NW-SE striking fault zone we observe NNW-SSE striking sinistral strike-slip and normal faulting micro-earthquakes which belong to a heterogeneous deformation zone with complex faulting. In Figure 1 we summarize our current model for the ASZ and its surroundings. The detection of many micro-earthquakes and the related active faults was only possible with the help of the additional temporal recording stations in the region and the studies of a PhD student (S.M.). We thank the DFG for funding our project and the State Earthquake Service Baden-Württemberg in Freiburg for providing data (Az. 4784//18_3303)

Asymptotic Level Density of the Elastic Net Self-Organizing Feature Map

Whileas the Kohonen Self Organizing Map shows an asymptotic level density following a power law with a magnification exponent 2/3, it would be desired to have an exponent 1 in order to provide optimal mapping in the sense of information theory. In this paper, we study analytically and numerically the magnification behaviour of the Elastic Net algorithm as a model for self-organizing feature maps. In contrast to the Kohonen map the Elastic Net shows no power law, but for onedimensional maps nevertheless the density follows an universal magnification law, i.e. depends on the local stimulus density only and is independent on position and decouples from the stimulus density at other positions.Comment: 8 pages, 10 figures. Link to publisher under http://link.springer.de/link/service/series/0558/bibs/2415/24150939.ht

Airborne field strength monitoring

In civil and military aviation, ground based navigation aids (NAVAIDS) are still crucial for flight guidance even though the acceptance of satellite based systems (GNSS) increases. Part of the calibration process for NAVAIDS (ILS, DME, VOR) is to perform a flight inspection according to specified methods as stated in a document (DOC8071, 2000) by the International Civil Aviation Organization (ICAO). One major task is to determine the coverage, or, in other words, the true signal-in-space field strength of a ground transmitter. This has always been a challenge to flight inspection up to now, since, especially in the L-band (DME, 1GHz), the antenna installed performance was known with an uncertainty of 10 dB or even more. In order to meet ICAO's required accuracy of ±3 dB it is necessary to have a precise 3-D antenna factor of the receiving antenna operating on the airborne platform including all losses and impedance mismatching. Introducing precise, effective antenna factors to flight inspection to achieve the required accuracy is new and not published in relevant papers yet. The authors try to establish a new balanced procedure between simulation and validation by airborne and ground measurements. This involves the interpretation of measured scattering parameters gained both on the ground and airborne in comparison with numerical results obtained by the multilevel fast multipole algorithm (MLFMA) accelerated method of moments (MoM) using a complex geometric model of the aircraft. First results will be presented in this paper