Search results for "SPECTRA"
showing 10 items of 3542 documents
Transfer reactions on light exotic nuclei studied with CHIMERA detector at LNS
2014
The kinematical coincidence method is used to extract angular distribution of elastic scattering and transfer reactions. The detected light particle energy spectra are used to extract the angular distribution with around 1° resolution in the Center of Mass (CM) system. Examples with 10Be beam are presented. In the case of proton scattering, γ-ray coincidences are used to discriminate excited levels population from elastic scattering. © Owned by the authors, published by EDP Sciences, 2014.
On the soft excess in the x-ray spectrum of circinus X-1: Revisitation of the distance to circinus X-1
2005
We report on a 300 ks BeppoSAX (0.12-200 keV) observation of Circinus X-1 (Cir X-1) at phases between 0.62 and 0.84 and on a 90 ks BeppoSAX observation of Cir X-1 at phases 0.11-0.16. Using the canonical model adopted until now to fit the energy spectrum of this source, large residuals appear below 1 keV. These are well fitted using an equivalent hydrogen column of 0.66¿1022 cm-2, adding absorption edges of O VII, O VIII, and Ne IX in the spectra extracted from the observation at phases 0.62-0.84 and adding absorption edges of O VII, O VIII, Mg XI, and Mg XII and absorption lines of O VIII and Mg XII in the spectra extracted from the observation at phases 0.11-0.16. During the observation a…
Comparison of hydrogen Balmer-alpha Stark profiles measured at high electron densities with theoretical results
2005
Profiles of the H-alpha line calculated using the full computer simulation method (FCSM) and the standard theory (ST) agree excellently with a measured profile (at an electron density of Ne = 9.0 × 1016 cm−3 and temperature T = 12 600 K) in an argon–hydrogen (minority) arc plasma. Calculated widths (FCSM) and shifts (ST) also agree well with experimental data from flash-tube plasmas and gas-linear pinch plasmas. Some discrepancies are probably caused by experimental flaws. Our analysis of the so-called generalized theory (GT) shows that this theory is burdened with un-physical approximations, and consequently so are all subsequent modifications based on GT. It is shown that the so-called ac…
Study of the far wing of the Balmer α line of hydrogen perturbed by collisions with protons
2002
The theory of the Balmer α line of atomic hydrogen perturbed by collisions with protons predicts quasi-molecular satellites in the line wing due to H-H+ collisions. Measurements of the spectrum of a laser-produced plasma confirm the existence of the strongest of these features.
Rotational and vibrational spectra of quantum rings
2000
One can confine the two-dimensional electron gas in semiconductor heterostructures electrostatically or by etching techniques such that a small electron island is formed. These man-made ``artificial atoms'' provide the experimental realization of a text-book example of many-particle physics: a finite number of quantum particles in a trap. Much effort was spent on making such "quantum dots" smaller and going from the mesoscopic to the quantum regime. Far-reaching analogies to the physics of atoms, nuclei or metal clusters were obvious from the very beginning: The concepts of shell structure and Hund's rules were found to apply -- just as in real atoms! In this Letter, we report the discovery…
X-ray spectroscopy of the Hertzsprung-gap giant star 31 Com, observed with XMM-Newton
2003
We have analysed the XMM-Newton X-ray spectra of the yellow giant 31 Com with the aim of deriving information on the coronal structures of this archetypical Hertzsprung-gap star. To determine the emission measure distribution vs. temperature, EM(T), and the elemental abundances of the coronal plasma, with an accurate line-based approach, we have developed a new method for simple and accurate line measurements, based on rebinning and co-adding the two RGS spectra. We have reconstructed the EM(T) independently with both APED and CHIANTI atomic databases in order to investigate possible differences in the final outcome of the analysis, and we have obtained consistent results. The derived emiss…
X-ray emission from MP Muscae: an old classical T Tauri star
2007
We study the properties of X-ray emitting plasma of MP Mus, an old classical T Tauri star. We aim at checking whether an accretion process produces the observed X-ray emission and at deriving the accretion parameters and the characteristics of the shock-heated plasma. We compare the properties of MP Mus with those of younger classical T Tauri stars to test whether age is related to the properties of the X-ray emission plasma. XMM-Newton X-ray spectra allows us to measure plasma temperatures, abundances, and electron density. In particular the density of cool plasma probes whether X-ray emission is produced by plasma heated in the accretion process. X-ray emission from MP Mus originates from…
In-beam spectroscopy of $^{253,254}$No
2002
In-beam conversion electron spectroscopy experiments have been performed on the transfermium nuclei 253,254No using the conversion electron spectrometer SACRED in nearly collinear geometry in conjunction with the gas-filled separator RITU at the University of Jyvaskyla. The experimental setup is discussed and the spectra are compared to Monte Carlo simulations. The implications for the ground-state configuration of 253No are discussed.
A semiconductor detector telescope electron spectrometer
1971
Abstract A simple d E d x+E type semiconductor detector telescope electron spectrometer featuring high detection efficiency and effective discrimination against γ-rays and heavy particles is described. The line shape of the spectrometer is better than that of a single detector of corresponding size; at 1 MeV, the peak-to-total ratio is approximately 0.8. The device is suited to the study of beta-ray spectra and conversion electron lines at energies above about 0.4 MeV.
Revised values for the nuclear quadrupole moments ofS33andS35
2014
High-level quantum-chemical calculations are reported for the sulfur electric-field gradients of the CS and SiS molecules. Highly accurate values are obtained in these calculations by using coupled-cluster methods for the treatment of electron correlation together with large atomic-orbital basis sets and by taking into account relativistic effects. The computational results for the sulfur electric-field gradient are used to determine revised values for the $^{33}\mathrm{S}$ and $^{35}\mathrm{S}$ quadrupole moments, thereby taking advantage of available accurate values for the sulfur quadrupole couplings of CS and SiS from the analysis of rotational spectra. The derived values of $\ensuremat…