Stability conditions for the solutions of the Half-Projected Hartree-Fock scheme. The lithium-hydride ground state

4 págs.; 1 fig.; 2 tabs.The stability conditions for the solutions of a two-unrestricted-determinant function (the half-projected Hartree-Fock function) are deduced from the necessary requirements for the minimization of the energy functional. The theory is applied to the case of the LiH ground state, in order to investigate the various solutions encountered in the variational problem. It is found that the two lowest solutions are local minima. The number of these solutions is estimated and their significance discussed as a function of the nuclear separation. © 1977 The American Physical Society.Peer Reviewe

IEA SHC Task 42 / ECES Annex 29 WG A1: Engineering and Processing of PCMs, TCMs and Sorption Materials

An overview on the recent results on the engineering and characterization of sorption materials, PCMs and TCMs investigated in the working group WG A1 "Engineering and processing of TES materials" of IEA SHC Task 42 / ECES Annex 29 (Task 4229) entitled "Compact Thermal Energy Storage" is presented

NectarCAM : a camera for the medium size telescopes of the Cherenkov Telescope Array

NectarCAM is a camera proposed for the medium-sized telescopes of the Cherenkov Telescope Array (CTA) covering the central energy range of ~100 GeV to ~30 TeV. It has a modular design and is based on the NECTAr chip, at the heart of which is a GHz sampling Switched Capacitor Array and a 12-bit Analog to Digital converter. The camera will be equipped with 265 7-photomultiplier modules, covering a field of view of 8 degrees. Each module includes the photomultiplier bases, high voltage supply, pre-amplifier, trigger, readout and Ethernet transceiver. The recorded events last between a few nanoseconds and tens of nanoseconds. The camera trigger will be flexible so as to minimize the read-out dead-time of the NECTAr chips. NectarCAM is designed to sustain a data rate of more than 4 kHz with less than 5\% dead time. The camera concept, the design and tests of the various subcomponents and results of thermal and electrical prototypes are presented. The design includes the mechanical structure, cooling of the electronics, read-out, clock distribution, slow control, data-acquisition, triggering, monitoring and services.Comment: In Proceedings of the 34th International Cosmic Ray Conference (ICRC2015), The Hague, The Netherlands. All CTA contributions at arXiv:1508.0589

Papel de las diatomeas como indicadores del grado de afección de embalses receptores de AMD: influencia del PH en el modo de ocurrencia

Este trabajo se basa en el estudio de 23 embalses ubicados en la Faja Pirítica Ibérica para llevar a cabo una clasificación ambiental basada en las comunidades de Diatomeas, con especial interés en aquellas acidófilas o ácido tolerantes, para definer la relación de estas comunidades con la físico-química de las aguas. Para ello, la distribución de diatomeas bentónicas se ha caracterizado, en particular en relación con el pH del medio, que ha permitido entender el papel de las diatomeas como indicadores de AMD en los embalses. Los resultados obtenidos confirmaron que las comunidades de diatomeas responden a variaciones en el pH y que el análisis cluster refleja los cambios en las comunidades de los embalses. Se verificó una relación de dependencia entre la abundancia y la distribución de las especies en relación con el pH del agua.Twenty three reservoirs located in the Iberian Pyrite Belt were studied in order to carry out an environmental assessment based on the communities of Diatoms, with special interest in those that present an acidophilic or acid-tolerant profile and to define the relation of these communities with the physical-chemical characteristics of the water. For this purpose, the distribution of benthic diatoms has been studied, in particular in relation to the pH of the medium, which has allowed. understanding the role of diatoms as indicators of AMD in the reservoirs. The obtained results confirmed that the diatom communities respond to variations in pH and that the cluster analysis reflects those changes in the communities of the reservoirs. A relationship of dependence between the abundance and distribution of the species under study with respect to the pH of the water was verified.info:eu-repo/semantics/publishedVersio

The Cherenkov Telescope Array Large Size Telescope

The two arrays of the Very High Energy gamma-ray observatory Cherenkov Telescope Array (CTA) will include four Large Size Telescopes (LSTs) each with a 23 m diameter dish and 28 m focal distance. These telescopes will enable CTA to achieve a low-energy threshold of 20 GeV, which is critical for important studies in astrophysics, astroparticle physics and cosmology. This work presents the key specifications and performance of the current LST design in the light of the CTA scientific objectives.Comment: 4 pages, 5 figures, In Proceedings of the 33rd International Cosmic Ray Conference (ICRC2013), Rio de Janeiro (Brazil). All CTA contributions at arXiv:1307.223

The major upgrade of the MAGIC telescopes, Part II: A performance study using observations of the Crab Nebula

MAGIC is a system of two Imaging Atmospheric Cherenkov Telescopes located in the Canary island of La Palma, Spain. During summer 2011 and 2012 it underwent a series of upgrades, involving the exchange of the MAGIC-I camera and its trigger system, as well as the upgrade of the readout system of both telescopes. We use observations of the Crab Nebula taken at low and medium zenith angles to assess the key performance parameters of the MAGIC stereo system. For low zenith angle observations, the standard trigger threshold of the MAGIC telescopes is ~50GeV. The integral sensitivity for point-like sources with Crab Nebula-like spectrum above 220GeV is (0.66+/-0.03)% of Crab Nebula flux in 50 h of observations. The angular resolution, defined as the sigma of a 2-dimensional Gaussian distribution, at those energies is < 0.07 degree, while the energy resolution is 16%. We also re-evaluate the effect of the systematic uncertainty on the data taken with the MAGIC telescopes after the upgrade. We estimate that the systematic uncertainties can be divided in the following components: < 15% in energy scale, 11-18% in flux normalization and +/-0.15 for the energy spectrum power-law slope.Comment: 21 pages, 25 figures, accepted for publication in Astroparticle Physic