Μελέτη της ελαστικής και ανελαστικής σκεδάσης - 1Η(6Ηe, 6He) 1H, 1H (6He, 6He ́)1H ́ - με το ανιχνευτικό σύστημα must

The purpose of the present study is twofold, to probe both the nuclear potential, as well as the structure of the radioactive nucleus 6He, which belongs to the category of the exotic borromean systems. The method used, is based on the determination of angular distribution, of the elastic and the inelastic scattering of protons from 6He in inverse kinematics, at a wide angular range with good resolution. In order to achieve this, we used the detection system of light particles, named MUST, which consists of eight telescopes with three detection stages each. This enabled a) the separation ofprotons from other light particles and b) the determination of the position and energy of the scattered protons in the telescopes. The theoretical analysis of data was made by using microscopic models (JLM and shell model) and m acroscopic models (Becchetti - Greenlees and CH89 phenomenological potentials). Concerning the analysis into the context of JLM calculations, it has been made clear the reduction of the real part of the optical potential, with a simultaneous increase of the imaginary,suggesting the presence of halo. M oreover, by studying the angular distribution of the resonance at 1.797 MeV, in the context of shell model calculations, the existence of halo at the 6He nucleus, was demonstrated. Furthermore, the determ ination of a mean value of nuclear deformation of that level was achieved. Finally, some new excited states - resonances of the continuum were found at 2.8,4, 7, 8 and 11 M eV, for which we attempted to determine their spin and multipolarity.Στο παρόν σύγγραμμα επιχειρείται η κατανόηση τόσο της δομής όσο και του πυρηνικού δυναμικού του ραδιενεργού πυρήνα Έ ίε, ο οποίος ανήκει στην κατηγορία των εξωτικών βορρομειακών συστημάτων. Η μέθοδος που ακολουθήθηκε ήταν ο προσδιορισμός των γωνιακών κατανομών της ελαστικής και ανελαστικής σκέδασης πρωτονίων σε αντίστροφη κινηματική σε μεγάλο γωνιακό εύρος και με καλή διακριτική ικανότητα. Για το σκοπό αυτό χρησιμοποιήθηκε το ανιχνευτικό σύστημα ελαφρών σωματιδίων M UST που απαρτίζεται από οκτώ τηλεσκόπια. Το κάθε τηλεσκόπιο αποτελείται από τρία στάδια ανίχνευσης, που επιτρέπουν τον διαχωρισμό των πρωτονίων από άλλα ελαφρά σωμάτια και τη μέτρηση της ενέργειας και της θέσης τους. Η θεωρητική ανάλυση των δεδομένων έγινε με τη χρήση μικροσκοπικών προτύπων (JLM και πρότυπο των φλοιών) και μακροσκοπικών προτύπων με χρήσητων φαινομενολογικών δυναμικών των Becchetti - Greenlees και το CH89. Στην περίπτωση του προτύπου JLM κατέστη σαφές ότι απαιτείται η ελάττωση του πραγματικού μέρους του οπτικού δυναμικού με ταυτόχρονη αύξηση του φανταστικού υποδεικνύοντας καταρχάς την ύπαρξη άλω. Εξάλλου, από τη μελέτη της γωνιακής κατανομής του συντονισμού στα 1.797 MeV στα πλαίσια του προτύπου των φλοιών αποδείχθηκε η ύπαρξη άλω στον πυρήνα του 6He. Έ γινε, επιπλέον, εφικτός οπροσδιορισμός μιας μέσης τιμής της πυρηνικής παραμόρφωσης του επιπέδου αυτού. Τέλος αναδείχθηκαν νέες διεγερμένες καταστάσεις - συντονισμοί στο συνεχές στα 2.8, 4, 7, 8 και 11 MeV, για τις οποίες έγινε προσπάθεια απόδοσης του spin και της ομοτιμίας τους

Dissolution and sorption mechanisms at the aluminosilicate and carbonate mineral-AMD (Acid Mine Drainage) interface

Aluminosilicate/silicate and carbonate materials (pure and industrial) interacted with natural Acid Mine Drainage (AMD) under ambient conditions for different time periods in order to elucidate the chemical processes at the aluminosilicate and carbonate mineral-AMD interface. More precisely, powdered materials were subjected to macroscopic neutralization experiments (using on-line pH-measurements, Inductively Coupled Plasma Optical Emission Spectroscopy, Powder X-ray Diffraction and Scanning Electron Microscopy with Energy Dispersive Spectroscopy), whereas interacted mm-sized single crystals were examined by means of nanoscale microscopic (in-situ Atomic Force Microscopy) and surface & bulk spectroscopic techniques (X-ray Photoelectron Spectroscopy, 12C-Rutherford Backscattering Spectroscopy, Solid-State 29Si and 27Al Magic-Angle-Spinning Nuclear Magnetic Resonance). The carbonates were proven to be more effective for neutralization of AMD, related to adequate removal of metals from the contaminated aqueous medium, but they are readily dissolved. The application of aluminosilicate/silicates showed that the removal of metals is considerably lower, and the pH stabilized at lower values, but they are more resistant. The investigation of interacted zeolite and calcite crystals revealed changes to the macrotopography, microtopography and nanotopography of surfaces. It was indicated that coupled dissolution and sorption (surface precipitation/co-precipitation, nucleation/crystal growth, adsorption or even absorption-including solid-state diffusion) phenomena occur simultaneously. Based on the experimental results, two generalized models -in nano(molecular)-scale- can be suggested regarding interaction of AMD with aluminosilicate and carbonate mineral surfaces

Dissolution and sorption mechanisms at the aluminosilicate and carbonate mineral-AMD (Acid Mine Drainage) interface

Aluminosilicate/silicate and carbonate materials (pure and industrial) interacted with natural Acid Mine Drainage (AMD) under ambient conditions for different time periods in order to elucidate the chemical processes at the aluminosilicate and carbonate mineral-AMD interface. More precisely, powdered materials were subjected to macroscopic neutralization experiments (using on-line pH-measurements, Inductively Coupled Plasma Optical Emission Spectroscopy, Powder X-ray Diffraction and Scanning Electron Microscopy with Energy Dispersive Spectroscopy), whereas interacted mm-sized single crystals were examined by means of nanoscale microscopic (in-situ Atomic Force Microscopy) and surface & bulk spectroscopic techniques (X-ray Photoelectron Spectroscopy, 12C-Rutherford Backscattering Spectroscopy, Solid-State 29Si and 27Al Magic-Angle-Spinning Nuclear Magnetic Resonance). The carbonates were proven to be more effective for neutralization of AMD, related to adequate removal of metals from the contaminated aqueous medium, but they are readily dissolved. The application of aluminosilicate/silicates showed that the removal of metals is considerably lower, and the pH stabilized at lower values, but they are more resistant. The investigation of interacted zeolite and calcite crystals revealed changes to the macrotopography, microtopography and nanotopography of surfaces. It was indicated that coupled dissolution and sorption (surface precipitation/co-precipitation, nucleation/crystal growth, adsorption or even absorption-including solid-state diffusion) phenomena occur simultaneously. Based on the experimental results, two generalized models -in nano(molecular)-scale- can be suggested regarding interaction of AMD with aluminosilicate and carbonate mineral surfaces

Capture reaction cross-section measurements relevant to p process: the case of (α , γ) reactions on

The cross sections of the 72Ge( α , γ)76Se and 1°7Ag(ρ, γ)1°8Cd reactions were measured at energies relevant to p-process nucleosynthesis. The new data, together with cross section results from our previous ( α , γ) measure-ments on 65Cu and 118Sn and other ( α , γ) cross-section data reported in lit-erature are compared with statistical model calculations performed using the latest version (1.9) of the statistical model code TALYS. In addition, the effect on these calculations of different combinations of the optical model potentials (OMPs), nuclear level densities (NLDs) and γ-ray strength functions (γSFs) entering the calculations was investigated

Capture reaction cross-section measurements relevant to p process: the case of (α , γ) reactions on 63Cu, 72Ge,118Sn and the 107Ag(ρ, γ)108Cd reaction

The cross sections of the 72Ge( α , γ)76Se and 1°7Ag(ρ, γ)1°8Cd reactions were measured at energies relevant to p-process nucleosynthesis. The new data, together with cross section results from our previous ( α , γ) measure-ments on 65Cu and 118Sn and other ( α , γ) cross-section data reported in lit-erature are compared with statistical model calculations performed using the latest version (1.9) of the statistical model code TALYS. In addition, the effect on these calculations of different combinations of the optical model potentials (OMPs), nuclear level densities (NLDs) and γ-ray strength functions (γSFs) entering the calculations was investigated

The FIDIAS project: Development of a Micromegas TPC for the detection of low-energy heavy ions

International audienceTime Projection Chambers are widely used since many years for tracking and identification of charged particles in high energy physics. We present here a new R&D project, called FIDIAS, meant to investigate the feasibility of a Micromegas TPC for low energy heavy ions detection. In this framework, a TPC prototype based on Micromegas bulk technique has been extensively tested with spontaneous fission source. A deep analysis of the experimental results has been realized leading to a full characterization of the prototype in terms of gain, energy resolution and track reconstruction as a function of three working gas: helium, neon and argon. The encouraging results have also been compared to simulations, showing the Micromegas TPC is a very well suited detector for the detection of heavy ions in nuclear reactions at low energy

Systematic measurements of proton- and alpha-capture cross sections relevant to the modelling of the p process

Several in-beam cross section measurements of proton- as well as α-capture reactions in the Se-Sb region have been carried out to obtain global input parameters for Hauser-Feshbach (HF) calculations. In total, 20 (p,γ) and 7 (α, γ) reactions were measured. We compare some of these results with Hauser-Feshbach calculations using various optical model potentials and nuclear level densities. © 2005 Elsevier B.V. All rights reserved.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Proton and alpha-particle capture reactions at sub-Coulomb energies relevant to the p process

Several cross-section measurements of proton as well as α-particle capture reactions in the Se-Sb region have been carried out at sub-Coulomb energies with the aim to obtain global input parameters for Hauser-Feshbach (HF) calculations. Some of the results are compared with HF calculations using various optical model potentials and nuclear level densities. © 2005 IOP Publishing Ltd.SCOPUS: cp.jinfo:eu-repo/semantics/publishe