XUV generation from plasma produced by a XeCl excimer laser on a Cu target

Summary We present a detailed study of XUV and soft X-ray emission from Cu plasma produced by an excimer laser at intensitiesI _L≦8·10¹¹ W/cm². The XeCl excimer laser (ψ≈308 nm) delivers pulses with energyE _L≈2.3 J, temporal durationt _L≈100 ns and brightnessB≧10¹⁴ W/cm² sr. We recorded a spectral conversion efficiency η=0.5% eV⁻¹ forI _L=4·10¹¹W/cm² in the aluminium window at 73eV with a harder X-ray tail around ≈400eV. We also measured the dependence of X-ray signal on laser intensity and viewing angle. Experimental results have been compared with some analytical laser-plasma interaction models.     

Contributions to the Boltzmann-like model for traffic flow. Numerical studies and experimental validations for concentration-dependent programs

Summary A Boltzmann-like model for vehicular traffic on highway, recently proposed[10], is analyzed. Both the model for a ?rigid? driving program and for a concentration-dependent driving program are considered, and the solutions for the homogeneous and stationary case are determined for a few theoretical and experimental speed distributions. The results are compared with the solutions of the Prigogine model; a comparison with experimental data is also given.

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Sommario Si analizza il modello tipo Boltzmann recentemente proposto [10] per il traffico automobilistico su autostrada. Si considerano sia il modello per programma di guida rigido sia per programma di guida dipendente dalla concentrazione, e si danno le soluzioni per il caso omogeneo e stazionario per alcune distribuzioni teoriche e sperimentali di velocità desiderate. I risultati sono confrontati con i risultati del modello di Prigogine e con dati sperimentali.

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Research performed under contract with the Committee for Mathematical Sciences of the C.N.R.     

Non-paulian Nuclear Processes in Highly Radiopure NaI(Tl): Status and Perspectives

Searches for non-paulian nuclear processes, i.e. processes normally forbidden by the Pauli–Exclusion–Principle (PEP) with highly radiopure NaI(Tl) scintillators allow the test of this fundamental principle with high sensitivity. Status and perspectives are addressed.     

Syn-Anti Isomerism in Arylthioamides: 1H and 13C-N. M. R. Configurational Analysis of 6-Aryl-3-thioaroyl-3, 4-Dihydro-2H-1, 3, 5-Thiadiazines

Recently we have reported on a direct synthetic route to the new class of 6-aryl-3-thioaroyl-3, 4-dihydro-2H-1, 3, 5-thiadiazines⁽¹⁾     

Contribution to the external gamma dose rate from <Superscript>137</Superscript>Cs and <Superscript>40</Superscript>K activity concentrations determined in the vertical profile of sandy beaches

Sampling sites, located along the Calabria and Basilicata Regions coastal beaches (south of Italy), were selected to assess the external gamma dose rate in air, 1 m above ground, and to estimate the fraction attributable to the radiocesium and radiopotassium contents along the vertical sand profile. Mean values for the gamma dose rate were: 76±30 nGy·h⁻¹. ¹³⁷Cs and ⁴⁰K deposition densities in sand samples were determined for each sampling site (mean values 0.24±0.22 kBq·m⁻² and 178±88 kBq·m⁻², respectively). The ¹³⁷Cs external dose rate contribution was assessed using a Monte Carlo simulation code. The method gives an estimation of the contribution to the external gamma dose rate of each sand layer along the vertical profile. The dose rate associated with the ¹³⁷Cs content in sand was 0.16±0.14 nGy·h⁻¹. The cosmic radiation and ⁴⁰K contributions to the external gamma dose rate were estimated using the UNSCEAR methodologies. The values obtained were 34±3 nGy·h⁻¹ and 18±9 nGy·h⁻¹, respectively.     

Signals from dark Universe: DAMA/LIBRA at LNGS

The DAMA/LIBRA set-up (about 250 kg highly radiopure NaI(Tl) sensitive mass) is running at the Gran Sasso National Laboratory of the INFN. The first DAMA/LIBRA results point out the presence of a dark matter particle component in the galactic halo, as well as the former DAMA/NaI set-up; cumulatively the data support such evidence at 8.2σ CL and satisfy all the peculiarities of the dark matter annual modulation signature.     

Concentration, distribution and characteristics of depleted uranium (DU) in the Kosovo ecosystem: A comparison with the uranium behavior in the environment uncontaminated by DU

The smear samples of the penetrator were analyzed for the determination of the uranium composition. The obtained relative composition (m/m) of uranium isotopes in all the smear samples is in the range of 99.76-99.78% for ²³⁸U, 0.000659-0.000696% for ²³⁴U, 0.213-0.234% for ²³⁵U, and 0.00274-0.00328% for ²³⁶U, showing characteristics of depleted uranium (DU). The uranium concentrations in Kosovo soil and water samples as well as biological samples were investigated. It was found that the uranium concentrations in the Kosovo soil samples are in the range of 11.3-2.26·10⁵ Bq·kg^-1 for ²³⁸U, 10.3-3.01·10⁴ Bq·kg^-1 for ²³⁴U, 0.60-3251 Bq·kg^-1 for ²³⁵U, and ￡0.019-1309 Bq·kg^-1 for ²³⁶U. The obtained activity ratios are in the range of 0.112-1.086 for ²³⁴U/²³⁸U, 0.0123-0.1144 for ²³⁵U/²³⁸U, and 0-0.0078 for ²³⁶U/²³⁸U, indicating the presence of DU in about 77% of the surface soil samples. At a specific site, the DU inventory in the surface soil is about 140 mg·cm^-2, which is 1.68·10⁶ times higher as the estimated mean DU dispersion rate in the region. The uranium concentrations in Kosovo lichen, mushroom, bark, etc., are in the range of 1.97-4.06·10⁴ Bq·kg^-1 for ²³⁸U, 0.48-5158 Bq·kg^-1 for ²³⁴U, 0.032-617 Bq·kg^-1 for ²³⁵U, and ￡0.019-235 Bq·kg^-1 for ²³⁶U with mean activity ratios of 0.325±0.0223 for ²³⁴U/²³⁸U, of 0.0238±0.0122 for ²³⁵U/²³⁸U, and 0.0034±0.0028 for +U/²³⁸U, indicating the presence of DU in the entire sample. On the contrary, the uranium concentrations in Kosovo water samples are low, compared with the water samples collected in central Italy, indicating the presence of negligible amount of DU. The uranium isotopes in Kosovo waters do not constitute a risk of health at the present time. This revised version was published online in July 2006 with corrections to the Cover Date.     

Three‐dimensional frameworks built from piperazine‐2,5‐dione and simple metal salts (M = Co,Ni, Cu and Ag)

Compounds trans‐tetraaquadichloridocobalt(II)–piperazine‐2,5‐dione (1/1), [CoCl₂(H₂O)₄]·C₄H₆N₂O₂, (I), and trans‐tetraaquadichloridonickel(II)–piperazine‐2,5‐dione (1/1), [NiCl₂(H₂O)₄]·C₄H₆N₂O₂, (II), are isomorphous. In each structure, the metal complex and the piperazinedione unit both lie across centres of inversion in the space group P2₁/n. The [MCl₂(H₂O)₄] units (M = Co or Ni) are linked by O—H...Cl hydrogen bonds into sheets of R₂²(8) and R₄²(12) rings, and these sheets are linked by the piperazinedione components via a combination of O—H...O and N—H...Cl hydrogen bonds into a three‐dimensional framework. In catena‐poly[[[trans‐diaquacopper(II)]‐di‐μ‐chlorido] piperazine‐2,5‐dione solvate], {[CuCl₂(H₂O)₂]·C₄H₆N₂O₂}_n, (III), the metal ion and the piperazine unit both lie across centres of inversion in the space group I2/a. The coordination polymer forms chains of centrosymmetric [CuCl₂(H₂O)₂] units running parallel to [010] and these are linked by the piperazinedione units into a three‐dimensional framework structure. In poly[μ₃‐nitrato‐μ₂‐piperazine‐2,5‐dione‐silver(I)], [Ag(NO₃)(C₄H₆N₂O₂)]_n, (IV), the silver and nitrate ions lie on mirror planes in the space group Pnma, while the piperazinedione unit lies across a centre of inversion. The compound is a coordination polymer containing five‐coordinate approximately square‐pyramidal Ag, in which the ligating O atoms are derived from three different nitrate ligands and two different piperazinedione ligands. The ionic components form sheets in which each anion is coordinated to three different cations, and these sheets are linked into a three‐dimensional framework by the organic ligands, each of which coordinates to two different Ag centres. The significance of this study lies in its demonstration of a wide variety of framework types built from a common and very simple organic component with simple metal salts.