Slater-Pauling Behavior of the Half-Ferromagnetic Full-Heusler Alloys

Using the full-potential screened Korringa-Kohn-Rostoker method we study the full-Heusler alloys based on Co, Fe, Rh and Ru. We show that many of these compounds show a half-metallic behavior, however in contrast to the half-Heusler alloys the energy gap in the minority band is extremely small. These full-Heusler compounds show a Slater-Pauling behavior and the total spin-magnetic moment per unit cell (M_t) scales with the total number of valence electrons (Z_t) following the rule: M_t=Z_t-24. We explain why the spin-down band contains exactly 12 electrons using arguments based on the group theory and show that this rule holds also for compounds with less than 24 valence electrons. Finally we discuss the deviations from this rule and the differences compared to the half-Heusler alloys.Comment: 10 pages, 8 figures, revised figure 3, new text adde

Measurement of event-shape observables in Z→ℓ+ℓ− events in pp collisions at √ s=7 TeV with the ATLAS detector at the LHC

Event-shape observables measured using charged particles in inclusive $Z$-boson events are presented, using the electron and muon decay modes of the $Z$ bosons. The measurements are based on an integrated luminosity of $1.1 {\rm fb}^{-1}$ of proton--proton collisions recorded by the ATLAS detector at the LHC at a centre-of-mass energy $\sqrt{s}=7$ TeV. Charged-particle distributions, excluding the lepton--antilepton pair from the $Z$-boson decay, are measured in different ranges of transverse momentum of the $Z$ boson. Distributions include multiplicity, scalar sum of transverse momenta, beam thrust, transverse thrust, spherocity, and $\mathcal{F}$-parameter, which are in particular sensitive to properties of the underlying event at small values of the $Z$-boson transverse momentum. The Sherpa event generator shows larger deviations from the measured observables than Pythia8 and Herwig7. Typically, all three Monte Carlo generators provide predictions that are in better agreement with the data at high $Z$-boson transverse momenta than at low $Z$-boson transverse momenta and for the observables that are less sensitive to the number of charged particles in the event.Comment: 36 pages plus author list + cover page (54 pages total), 14 figures, 4 tables, submitted to EPJC, All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2014-0

Search for jet extinction in the inclusive jet-pT spectrum from proton-proton collisions at s=8 TeV

Published by the American Physical Society under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published articles title, journal citation, and DOI.The first search at the LHC for the extinction of QCD jet production is presented, using data collected with the CMS detector corresponding to an integrated luminosity of 10.7  fb−1 of proton-proton collisions at a center-of-mass energy of 8 TeV. The extinction model studied in this analysis is motivated by the search for signatures of strong gravity at the TeV scale (terascale gravity) and assumes the existence of string couplings in the strong-coupling limit. In this limit, the string model predicts the suppression of all high-transverse-momentum standard model processes, including jet production, beyond a certain energy scale. To test this prediction, the measured transverse-momentum spectrum is compared to the theoretical prediction of the standard model. No significant deficit of events is found at high transverse momentum. A 95% confidence level lower limit of 3.3 TeV is set on the extinction mass scale

Searches for electroweak neutralino and chargino production in channels with Higgs, Z, and W bosons in pp collisions at 8 TeV

Searches for supersymmetry (SUSY) are presented based on the electroweak pair production of neutralinos and charginos, leading to decay channels with Higgs, Z, and W bosons and undetected lightest SUSY particles (LSPs). The data sample corresponds to an integrated luminosity of about 19.5 fb(-1) of proton-proton collisions at a center-of-mass energy of 8 TeV collected in 2012 with the CMS detector at the LHC. The main emphasis is neutralino pair production in which each neutralino decays either to a Higgs boson (h) and an LSP or to a Z boson and an LSP, leading to hh, hZ, and ZZ states with missing transverse energy (E-T(miss)). A second aspect is chargino-neutralino pair production, leading to hW states with E-T(miss). The decays of a Higgs boson to a bottom-quark pair, to a photon pair, and to final states with leptons are considered in conjunction with hadronic and leptonic decay modes of the Z and W bosons. No evidence is found for supersymmetric particles, and 95% confidence level upper limits are evaluated for the respective pair production cross sections and for neutralino and chargino mass values

Risk assessment (chemical and radiological) due to intake of uranium through the ingestion of drinking water around two proposed uranium mining areas, Jharkhan d, India

Uranium is known for both chemical and radiological toxicity. East Singhbhum is known for uranium mining, and radionuclides can be expected in its groundwater. Groundwater was collected around two proposed sites of Bagjata and Banduhurang and analysed for U(nat). The study reveals that the U(nat) varied from <0.5–11.2 and <0.5–27.5 µg.L -1 for the Bagjata and Banduhurang mining areas, respectively. The excess lifetime cancer risk due to the consumption of uranium in water was calculated to be in the range of 8.81 × 10-6 to 4.34 × 10-5 and 3.36 × 10-6 to 9.55 × 10-5 for the two study areas, which are within the acceptable cancer risk value of 1 × 10-4. However, the risk at a few locations is very close to the threshold value. The chemical risk evaluated by the hazard quotient was found to be within 0.05–0.23 and 0.02–0.6 for the two study areas and did not exceed the limit of 1. Thus, the concentration of U(nat) in the groundwater presently does not pose any serious threat to local people but must be monitored periodically and adequate actions must be taken in the few areas with elevated levels of uranium in the groundwater

A simple method for calibration of Lucas scintillation cell counting system for measurement of 226Ra and 222Rn

Known quantity of radium from high grade ore solution was chemically separated and carefully kept inside the cavity of a Lucas Cell (LC). The 222Rn gradually builds up and attain secular equilibrium with its parent 226Ra. This gives a steady count after a suitable buildup period (>25 days). This secondary source was used to calibrate the radon counting system. The method is validated in by comparison with identical measurement with AlphaGuard Aquakit. The radon counting system was used to evaluate dissolved radon in ground water sample by gross alpha counting in LC. Radon counting system measures the collected radon after a delay of >180 min by gross alpha counting. Simultaneous measurement also carried out by AlphaGuard Aquakit in identical condition. AlphaGuard measures dissolved radon from water sample by constant aeration in a closed circuit without giving any delay. Both the methods are matching with a correlation coefficient of >0.9. This validates the calibration of Lucas scintillation cell counting system by designed encapsulated source. This study provides an alternative for calibration in absence of costly Radon source available in the market. Keywords: Radon counting system, Calibration, Lucas cel

Ingestion of U(nat),

Ingestion of radionuclides through food intake accounts for a substantial part of radiation doses and vegetables constitute essential components of the diet, by contributing protein, vitamins, iron, calcium and other nutrients. Radionuclides can be apprehended in the ecosystem of the East Singhbhum region which is known for its viable grades of uranium. In the present study, vegetables were collected from the villages around the proposed Bagjata mining area and analysed for U(nat), 226Ra, 230Th and 210Po. The geometric mean concentration of U(nat), 226Ra, 230Th, and 210Po were 0.05, 0.09, 0.17 and 1.12 Bq kg-1 fresh weight, respectively. The intake of the radionuclides from vegetables was found to be 49.58 Bq y-1while the ingestion dose was calculated to be 11.51 µSv y-1, respectively. The estimated doses are reflecting the natural background dose via the route of ingestion, which is much below the 1 mSv limit set in the new ICRP recommendations. It is lower than the global average annual radiation dose of 2 400 µSv to man from the natural radiation sources as proposed by UNSCEAR. The total cancer risk due to the consumption of vegetables was calculated to be 6.65 × 10-9 which is negligible and much lower than the threshold risk value of 10-6. The study also reveals that water is more conducive for high radioactivity occurrence in vegetables compared to soil systems