Narrow Results

A new technique of spectrum analysis for PIXE based on the linear associative neural network has been developed. The network has high capability in the association of almost all elements across the periodic table in samples, in the quantification with wide dynamic range of the concentrations, and in the analysis speed.

The DAΦNE electron-positron collider at the Laboratori Nazionali di Frascati dell'INFN has made available a unique quality negative kaons “beam”. Two experiments, SIDDHARTA and AMADEUS, will use this beam to perform unprecedented precision measurements on kaonic atoms and kaonic nuclei. The scientific cases, together with the experimental setups, are briefly presented in this paper.

X-ray spectral parameters were determined for WZ Sge observed with the ROSAT PSPC. The raw data were fitted with various spectral models and the best fit spectral models are found to be that of Raymond–Smith and Thermal Bremsstrahlung. The best fit temperature was estimated to be kT ~ 2.17 keV while the column density was found to be N_H ~ 2.8 × 10²⁰cm^-2. The estimated 0.1–2.4 keV flux was in the range of log F = -12 ergs cm^-2s^-1.

WZ Sge stars show long outburst recurrence times and weak X-ray emissions during the quiescence states. It is possible to lengthen repetition cycles by decreasing the viscosity parameter (α); however there still remains the question why α is so small, specifically for these objects. The Coronal Siphon Model of Meyer and Meyer–Hofmeister¹ can explain these phenomenons successfully. For this reason, the equations of this model were applied to the results of spectral analysis. Using this model, the mass accretion rate, mass evaporation rate in corona and the radius of the corona were calculated to be 10^14.48 gr yr^-1, 10^-5.4 gr cm^-2 s^-1 and 10^9.7 cm, respectively. The obtained values suggest that the corona model can indeed operate in WZ Sge system.

University-scale Z-pinch generators are able to produce High Energy Density (HED) plasmas in a broad range of plasma parameters under well-controlled and monitored experimental conditions suitable for radiation studies. The implosion of X-pinch and wire array loads at a 1 MA generator yields short (1-20 nsec) x-ray bursts from one or several bright plasma spots near the wire cross point (for X-pinches) or along and near Z-pinch axis (for wire arrays). Such X- and Z-pinch HED plasma with scales from a few µm to several mm in size emits radiation in a broad range of energies from 10 eV to 0.5 MeV and is subject of our studies during the last ten years. In particular, the substantial number of experiments with very different wire loads was performed on the 1 MA Zebra generator and analyzed: X-pinch, cylindrical, nested, and various types of the novel load, Planar Wire Arrays (PWA). Also, the experiments at an enhanced current of 1.5-1.7 MA on Zebra using Load Current Multiplier (LCM) were performed. This paper highlights radiative signatures of X-pinches and Single and Double PWAs which are illustrated using the new results with combined wire loads from two different materials.