http://hdl.handle.net/20.500.11765/1580 2026-05-10T08:46:28Z 2026-05-10T08:46:28Z García Gil, Alejandro Manuel Muñoz Tuñón, Casiana Varela, Antonia María http://hdl.handle.net/20.500.11765/17644 2026-05-09T23:11:55Z 2010-01-01T00:00:00Z

Título : Atmosphere Extinction at the ORM on La Palma: A 20 yr Statistical Database Gathered at the Carlsberg Meridian Telescope Autor : García Gil, Alejandro Manuel; Muñoz Tuñón, Casiana; Varela, Antonia María Resumen : The Observatorio del Roque de los Muchachos (ORM), in the Canary Islands (Spain), was one of the candidates to host the future European Extremely Large Telescope (E-ELT) and is the site of the Gran Telescopio Canarias (GTC), the largest optical infrared facility to date. Sky transparency is a key parameter as it defines the quality of the photometry to be acquired in the astronomical observations. We present a study of the atmosphere extinction at the ORM, carried out after analysis of a database spanning more than 20 yr,1to our knowledge, the longest and most complete and homogeneous in situ database available for any observatory. It is based on photometric measurements in the V band and r′ band (transformed to the V-band extinction coefficient kV) using the Carlsberg Meridian Telescope (CMT). Clear seasonal variations that repeat yearly are observed. The median value of kV is 0.13 mag airmass-1; the mean value has a maximum in the summer months (June-September), corresponding to the season with maximum frequency of nights affected by dust or cirrus (∼29% in summer, but only ∼13% during the rest of the year). Two volcanic eruptions took place during the database baseline, which has enabled the study of the impact of volcanoes on the global atmosphere extinction. For the 5 yr of available information, we have estimated the average monthly weather downtime from the CMT data log, obtaining a result (20.7%) in reasonable agreement with earlier studies. The main conclusion of our study is that there is no significant evidence from the CMT data for any secular changes in kV over the 20 yr database baseline.

2010-01-01T00:00:00Z Sancho Sánchez, Pedro http://hdl.handle.net/20.500.11765/14873 2026-05-09T23:11:56Z 2010-01-01T00:00:00Z

Título : Identical two-particle interferometry in diffraction gratings Autor : Sancho Sánchez, Pedro Resumen : We study diffraction and interference of indistinguishable particles. We consider some examples where the wavefunctions and detection probabilities can be evaluated in an analytical way. The diffraction pattern of a two-particle system shows notorious differences for the cases of bosons, fermions and distinguishable particles. In the example of near-field interferometry, the exchange effects for two-fermion systems lead to the existence of planes at which the probability of double detection is null. We also discuss the relation with the approach to systems of identical particles based on correlation functions. In particular, we shall see that these functions reflect, as in noise interferometry, the underlying periodic structure of the diffraction grating.

2010-01-01T00:00:00Z Martínez Lozano, José Antonio Utrillas, María Pilar Núñez Mora, José Ángel Esteve Martínez, Anna Raquel Gómez Amo, José Luis Estellés Leal, Víctor Pedrós, Roberto http://hdl.handle.net/20.500.11765/14872 2026-05-09T23:11:56Z 2012-01-01T00:00:00Z

Título : Measurement and Analysis of Broadband UVB Solar Radiation in Spain Autor : Martínez Lozano, José Antonio; Utrillas, María Pilar; Núñez Mora, José Ángel; Esteve Martínez, Anna Raquel; Gómez Amo, José Luis; Estellés Leal, Víctor; Pedrós, Roberto Resumen : Measurements of broadband UVB irradiance (290–315 nm) at 14 locations in Spain for the period 2000–2009 have been used to generate instantaneous, hourly and daily values of irradiance (W m−2) and radiant exposure (kJ m−2). These measurements, and its statistical indices, have been analyzed. For the UVB irradiance, the values corresponding to July (maximum) and December (minimum) have been analyzed as representative of the year during the whole period for all locations. For the UVB radiant exposure, the temporal evolution of daily values has been evaluated for all locations to estimate an average yearly behavior. The accumulated radiant exposure for an average year has also been studied for each location. Finally, to determine possible trends in the evolution of the UVB levels, the linear regressions for the mean daily values for all locations have been determined.

2012-01-01T00:00:00Z Castro Lobera, María Paloma Velarde, Manuel G. Ardao Berdejo, José Perlado Martín, José Manuel Sedano, Luis http://hdl.handle.net/20.500.11765/14871 2026-05-09T23:11:58Z 2012-01-01T00:00:00Z

Título : Tritium clouds environmental impact in air into the Western Mediterranean Basin evaluation Autor : Castro Lobera, María Paloma; Velarde, Manuel G.; Ardao Berdejo, José; Perlado Martín, José Manuel; Sedano, Luis Resumen : The paper considers short-term releases of tritium (mainly but not only tritium hydride (HT)) to the atmosphere from a potential ITER-like fusion reactor located in the Mediterranean Basin and explores if the short range legal exposure limits are exceeded (both locally and downwind). For this, a coupled Lagrangian ECMWF/FLEXPART model has been used to follow real time releases of tritium. This tool was analyzed for nominal tritium operational conditions under selected incidental conditions to determine resultant local and Western Mediterranean effects, together with hourly observations of wind, to provide a short-range approximation of tritium cloud behavior. Since our results cannot be compared with radiological station measurements of tritium in air, we use the NORMTRI Gaussian model. We demonstrate an overestimation of the sequence of tritium concentrations in the atmosphere, close to the reactor, estimated with this model when compared with ECMWF/FLEXPART results. A Gaussian “mesoscale” qualification tool has been used to validate the ECMWF/FLEXPART for winter 2010/spring 2011 with a database of the HT plumes. It is considered that NORMTRI allows evaluation of tritium-in-air-plume patterns and its contribution to doses.

2012-01-01T00:00:00Z