Spin magnetization of strongly correlated electron gas confined in a two-dimensional finite lattice

The influence of disorder and interaction on the ground state polarization of the two-dimensional (2D) correlated electron gas is studied by numerical investigations of unrestricted Hartree-Fock equations. The ferromagnetic ground state is found to be plausible when the electron number is lowered and the interaction and disorder parameters are suitably chosen. For a finite system at constant electronic density the disorder induced spin polarization is cut off when the electron orbitals become strongly localized to the individual network sites. The fluctuations of the interaction matrix elements are calculated and brought out as favoring the ferromagnetic instability in the extended and weak localization regime. The localization effect of the Hubbard interaction term is discussed.Comment: 7 pages, 9 figure

Investigation of the Δn = 0 selection rule in Gamow-Teller transitions : The β-decay of 207 Hg

Gamow-Teller β decay is forbidden if the number of nodes in the radial wave functions of the initial and final states is different. This Δn=0 requirement plays a major role in the β decay of heavy neutron-rich nuclei, affecting the nucleosynthesis through the increased half-lives of nuclei on the astrophysical r-process pathway below both Z=50 (for N>82) and Z=82 (for N>126). The level of forbiddenness of the Δn=1ν1g 9/2 →π0g 7/2 transition has been investigated from the β − decay of the ground state of 207 Hg into the single-proton-hole nucleus 207 Tl in an experiment at the ISOLDE Decay Station. From statistical observational limits on possible γ-ray transitions depopulating the π0g 7/2 −1 state in 207 Tl, an upper limit of 3.9×10 −3 % was obtained for the probability of this decay, corresponding to log⁡ft>8.8 within a 95% confidence limit. This is the most stringent test of the Δn=0 selection rule to date

THE EXPLOITATION OF THE TULGHEŞ-GRINŢIEŞ URANIUM DEPOSIT. BETWEEN BENEFITS AND CONTROVERSY

The Exploitation of the Tulgheș-Grințieș Uranium Deposit. Between Benefits and Controversy. Romania is one of the few European states (alongside the Czech Republic, France, Germany, Ukraine) and one of the few in the world with uranium deposits (Canada, Australia, Niger, Namibia are others), mainly used in the energy sector. According to recent studies, the only currently exploited deposit (Crucea-Botușana, Suceava County) is nearly depleted (by 2019) and will be eventually shut down. For this reason, there are plans to open a new uranium mining facility in the Tulgheș-Grințieș area, where geological surveys have proven that the area holds the largest uranium deposit in the country. It will provide the necessary fuel for Cernavodă Nuclear Power Plant, for the two functional reactors, which have a total capacity of 706 MW each (producing roughly 18% of the country's electricity needs), as well as for units 3 and 4, not operational yet. The study at hand intends to emphasize several aspects regarding the exploitation possibilities for the uranium deposit from the two mineralized structures located in the fracture areas of the central Carpathian line, through which the crystalline overflows the Cretaceous Flysch. Furthermore, the environmental impact analysis as well as the long term safety and security of the population inhabiting the area will be of utmost importance

Radon Measurements and Radon Remediationin Băiţa-Ştei Pronearea

Băiţa-Ştei was the largest uranium reserve in Romania with estimated reserves of 450,000 tons of high grade metal. It was a large open pit mine in the northwest of Romania (West Carpathian Mountains), situated at 123 km south-east of Oradea, the capital of Bihor County. The transport during the time of sediment by Crişul Băiţa water course increased the uranium and radium content in the river meadow. The building material from Crişul Băiţariver bed (stone, gravel, sand) was used as construction material for the houses. In addition, some people living on this valley and surroundings after the opening exploitation used as building material the uranium waste from this mine. Preliminary indoor radon measurement (grab samples) in the villages situated on the route of ore transport (BăiţaPlai -Ştei) shown high radon concentrations, until 5000 Bq m−3. The new result obtained in this work in springer season 252 Bq m−3 is comparable with the annual means of 241 Bq m−3 and 229 Bq m−3 respectively, previously obtained, but more than twice times higher than the average value of 126 Bq m−3, computed for Romania. About 3000 of etched CR-39 track detectors were used followed by a selection of 20 houses proposed for remediation where a systematic investigation regarding radon sources was performed. The measured indoor radon concentration in the surveyed buildings ranged from 40 to 4000 Bq m−3. For experimental research, a representative pilot house was chosen. This house represents an example of a typical building from this area, with complex and various radon entry pathways which are correlated with the geology of soil. This building was chosen as pilot house due to the fact that it requires different ventilation systems or other remedial measures to be installe