Structural trends in atomic nuclei from laser spectroscopy of tin

Tin is the chemical element with the largest number of stable isotopes. Its complete proton shell, comparable with the closed electron shells in the chemically inert noble gases, is not a mere precursor to extended stability; since the protons carry the nuclear charge, their spatial arrangement also drives the nuclear electromagnetism. We report high-precision measurements of the electromagnetic moments and isomeric differences in charge radii between the lowest 1/2(+), 3/2(+), and 11/2(-) states in Sn117-131, obtained by collinear laser spectroscopy. Supported by state-of-the-art atomic-structure calculations, the data accurately show a considerable attenuation of the quadrupole moments in the closed-shell tin isotopes relative to those of cadmium, with two protons less. Linear and quadratic mass-dependent trends are observed. While microscopic density functional theory explains the global behaviour of the measured quantities, interpretation of the local patterns demands higher-fidelity modelling. Measurements of the hyperfine structure of chemical elements isotopes provide unique insight into the atomic nucleus in a nuclear model-independent way. The authors present collinear laser spectroscopy data obtained at the CERN ISOLDE and measure hyperfine splitting along a long chain of odd-mass tin isotopes.Peer reviewe

Evolution of nuclear structure of germanium isotopes around N = 40

Collinear laser spectroscopy measurements were performed on 68−74Ge isotopes (Z = 32) using the COLLAPS setup at ISOLDE/CERN. The hyperfine structure of the 4s24p2 3P1 → 4s24p5s 3P o 1 transition in the germanium atom was probed with laser light of 269 nm, produced by combining the frequency-mixing and frequency-doubling techniques. A detailed analysis of the hyperfine spectra of 69Ge, led to revised values of its magnetic and quadrupole moments, which deviate significantly from the results from an earlier study using the atomic beam magnetic resonance technique. The experimental moments of 69,71,73Ge agree well with the effective single-particle value for an odd neutron in respectively the νf5/2, νp1/2 and νg9/2 orbit, using $g^{eff}_s = 0.7 g^{free}_s , which might suggest rather pure configurations. However, a comparison with large-scale shell-model calculations using the JUN45 interaction, with 56Ni as a core and neutrons limited to N = 50, reveal rather mixed wave-functions. Through a comparison of the odd-N isotope magnetic and quadrupole moments with neighbouring isotones, the structural change from the single-particle nature of nickel to deformation in germanium is further investigated around N = 40. The experimental mean square charge radii of 68−74Ge are compared with the droplet model values revealing a weak subshell effect at N = 40 and an increased collectivity in the germanium isotopes, as compared to their lower-Z isotones. The odd-even staggering of the radii of the germanium isotopes is found to be larger than for the other isotopes in the region, with less than 40 neutrons. While only one value is available beyond N = 40, this value suggests a weakening of the odd-even staggering, but more neutron-rich data are needed to confirm this

Fission cross section measurement of 234U(n,f) using Micromegas detectors

Εθνικό Μετσόβιο Πολυτεχνείο--Μεταπτυχιακή Εργασία. Διεπιστημονικό-Διατμηματικό Πρόγραμμα Μεταπτυχιακών Σπουδών (Δ.Π.Μ.Σ.) “Φυσική και Τεχνολογικές Εφαρμογές

Radiation Dosimetry Estimations in the Venusian Atmosphere during Different Periods of Solar Activity

The new space era has expanded the exploration of other planets of our solar system. In this work, radiation quantities are estimated in the Venusian atmosphere using the software tool DYASTIMA/DYASTIMA-R, such as the energy deposit and the ambient dose equivalent rate. Monte Carlo simulations of the secondary particle cascades for different atmospheric layers were performed during solar minimum and solar maximum conditions, as well as during the extreme solar particle event that took place in October 1989, with a focus on the so-called Venusian zone of habitability

Radiation Exposure in the Lower Atmosphere during Different Periods of Solar Activity

In recent years, there has been a huge increase in air travel, both for business and leisure. For this reason, entities such as the European Commission and the International Committee on Radiological Protection have provided several recommendations for the radiation protection of aviation crews and frequent flyers, as well as highlighted the need for accurate tools for radiation assessment in the atmosphere. With a focus on the most frequent commercial flying altitudes, this work has performed dosimetry calculations in the lower atmosphere of Earth for different values of cut-off rigidity, covering the recent solar cycles 23 and 24. Results are based on Monte Carlo simulations performed with the validated Geant4 software application Dynamic Atmospheric Shower Tracking Interactive Model Application (DYASTIMA) and its extension, DYASTIMA-R

Radiation Exposure in the Lower Atmosphere during Different Periods of Solar Activity

In recent years, there has been a huge increase in air travel, both for business and leisure. For this reason, entities such as the European Commission and the International Committee on Radiological Protection have provided several recommendations for the radiation protection of aviation crews and frequent flyers, as well as highlighted the need for accurate tools for radiation assessment in the atmosphere. With a focus on the most frequent commercial flying altitudes, this work has performed dosimetry calculations in the lower atmosphere of Earth for different values of cut-off rigidity, covering the recent solar cycles 23 and 24. Results are based on Monte Carlo simulations performed with the validated Geant4 software application Dynamic Atmospheric Shower Tracking Interactive Model Application (DYASTIMA) and its extension, DYASTIMA-R

Strontium-90 pollution can be bioremediated with the green microalga Tetraselmis chui

The high strontium-90 uptake by the green microalga Tetraselmis chui is related to its ability to form strontium-rich inclusions of amorphous calcium carbonate (called micropearls). </p

Hemispherical Deflector Analyzer input lens optimization using SIMION

<p>A poster presented at HNPS2014,</p> <p>AUTh, Thessaloniki, Greece</p

First radiative proton capture measurements on 107,109-Ag and 112-Cd relevant to the p-process

One of the important, but still unsettled topics in Nuclear Astrophysics is the production of the <i>p</i>-nuclei [1,2]. The p-process relies on an extended reaction network, which can be described theoretically by the Hauser-Feshbach statistical model, which in turn relies strongly on experimental data. To provide reliable data for <i>p</i>-nuclei, an experimental campaign at the Tandem Accelerator Laboratory of NCSR "Demokritos'', focusing on measurements of cross-sections in the^107,109Ag(p,γ)^108,110Cd [3] and ¹¹²Cd(p,γ)¹¹³In [4]<br>reactions was carried out. Both reactions were studied using a set of four HPGe detectors via the in-beam γ-ray spectroscopy, while for the latter the activation method was additionally employed to account for the population of a low-lying isomeric state. Total cross sections for proton beam energies lying inside the Gamow window for energies relevant to <i>p</i>-process nucleosynthesis were obtained for the first time. Experimental results are compared to Hauser-Feshbach calculations performed with the latest version of the TALYS code (v1.9) [5]. An overall good agreement has been achieved. These results provide important new input for the theoretical description of the<i> p</i>-process, but additionally for the origin of the cross-point <i>p</i>-nucleus ¹¹³In.<div><br></div><div><b>References</b><br><br>[1] M. Arnould and S. Goriely, Phys. Rep. <b>384</b>, 1 (2003)<br>[2] T. Rauscher <i>et al.</i>, Rep. Prog. Phys. <b>76</b>, 066201 (2013)<br>[3] A. Khaliel <i>et al.</i>, Phys. Rev. C <b>96</b>, 035806 (2017)<br>[4] A. Psaltis <i>et al. </i>(2018), in prep.<br>[5] A. Koning, S. Hilaire and S. Goriely, TALYS-1.9, A Nuclear Reaction Program, NRG-1755 ZG Petten, The Netherlands (2017)</div><div><br></div><div>Poster presented at the 15^th International Symposium on Nuclei in the Cosmos (June 24-29, 2018 Assergi, L'Aquila, Italy)</div

THE GROUND-LEVEL ENHANCEMENT OF 2012 MAY 17: DERIVATION OF SOLAR PROTON EVENT PROPERTIES THROUGH THE APPLICATION OF THE NMBANGLE PPOLA MODEL

In this work, we apply an updated version of the Neutron Monitor (NM) Based Anisotropic GLE Pure Power Law (NMBANGLE PPOLA) model, in order to derive the characteristics of the ground-level enhancement (GLE) on 2012 May 17 (GLE71), the spectral properties of the related solar energetic particle (SEP) event, the spatial distributions of the high-energy solar cosmic ray fluxes at the top of the atmosphere, and the time evolution of the location of the GLE source. Our modeling, based uniquely on the use of ground-level NM data, leads to the following main results. The SEP spectrum related to GLE71 was rather soft during the whole duration of the event, manifesting some weak acceleration episodes only during the initial phase (at ~01:55-02:00 UT) and at ~02:30-02:35 UT and ~02:55-03:00 UT. The spectral index of the modeled SEP spectrum supports the coronal mass ejection-shock driven particle acceleration scenario, in agreement with past results based on the analysis of satellite measurements. During the initial phase of GLE71, the solar proton source at the top of the atmosphere was located above the northern hemisphere, implying that the asymptotic directions of viewing of the northern hemisphere NMs were more favorably located for registering the event than the southern ones. The spatial distribution of the solar proton fluxes at the top of the atmosphere during the main phase manifested a large variation along longitude and latitude. At the rigidity of 1 GV, the maximum primary solar proton flux resulted on the order of ~3 × 104 part. m-2 s-1 sr-1 GV-1