Investigating the possibility of leakage detection in water distribution networks using cosmic ray neutrons in the thermal region

Water distribution systems can experience high levels of leakage, originating from different sources, such as deterioration due to aging of pipes and fittings, material defects, and corrosion. In addition to causing financial losses and supply problems, leakages in treated water distribution also represent a risk for public health. Despite several techniques for leak detection are already available, there is still a lot of interest in new non-invasive approaches, especially for scenarios where acoustic techniques struggle, such as in noisy environmental conditions. In this work we investigated the possibility of using cosmic ray (CR) neutrons for the detection of underground leakages in water distribution networks, by exploiting the difference in the above ground thermal neutron flux between dry and wet soil conditions. The potential of the technique has been assessed by means of an extensive set of Monte Carlo simulations based on GEANT4, involving realistic scenarios based on the Italian aqueduct design guidelines. Simulation studies focused on sandy soils and results suggest that a significative signal, associated with a leakage, could be detected with a data-taking lasting from a few minutes to a half-hour, depending on the environmental soil moisture, the leaking water distribution in soil, and the soil chemical composition. Finally, a brief description of a new portable and low-cost detector for thermal neutrons, currently under commission, is also presented

HD 17156b: A Transiting Planet with a 21.2 Day Period and an Eccentric Orbit

We report the detection of transits by the 3.1 M_Jup companion to the V=8.17 G0V star HD 17156. The transit was observed by three independant observers on Sept. 9/10, 2007 (two in central Italy and one in the Canary Islands), who obtained detections at confidence levels of 3.0 sigma, 5.3 sigma, and 7.9 sigma, respectively. The observations were carried out under the auspices of the Transitsearch.org network, which organizes follow-up photometric transit searches of known planet-bearing stars during the time intervals when transits are expected to possibly occur. Analyses of the 7.9 sigma data set indicates a transit depth d=0.0062+/-0.0004, and a transit duration t=186+/-5 min. These values are consistent with the transit of a Jupiter-sized planet with an impact parameter b=a*cos(i)/R_star ~ 0.8. This planet occupies a unique regime among known transiting extrasolar planets, both as a result of its large orbital eccentricity (e=0.67) and long orbital period (P=21.2 d). The planet receives a 26-fold variation in insolation during the course of its orbit, which will make it a useful object for characterization of exoplanetary atmospheric dynamics.Comment: Accepted for publication to A&A, 4 pages, 2 figure

Photometry of comet 9P/Tempel 1 during the 2004/2005 approach and the Deep Impact module impact

The results of the 9P/Tempel 1 CARA (Cometary Archive for Amateur Astronomers) observing campaign is presented. The main goal was to perform an extended survey of the comet as a support to the Deep Impact (DI) Mission. CCD R, I and narrowband aperture photometries were used to monitor the $Af\rho$ quantity. The observed behaviour showed a peak of 310 cm 83 days before perihelion, but we argue that it could be distorted by the phase effect, too. The phase effect is roughly estimated around 0.0275 mag/degree, but we had no chance for direct determination because of the very similar geometry of the observed apparitions. The log-slope of $Af\rho$ was around -0.5 between about 180--100 days before the impact but evolved near the steady-state like 0 value by the impact time. The DI module impact caused an about 60%{} increase in the value of $Af\rho$ and a cloud feature in the coma profile which was observed just after the event. The expansion of the ejecta cloud was consistent with a fountain model with initial projected velocity of 0.2 km/s and $\beta$=0.73. Referring to a 25~000 km radius area centered on the nucleus, the total cross section of the ejected dust was 8.2/$A$ km$^2$ 0.06 days after the impact, and 1.2/$A$ km$^2$ 1.93 days after the impact ($A$ is the dust albedo). 5 days after the event no signs of the impact were detected nor deviations from the expected activity referring both to the average pre-impact behaviour and to the previous apparitions ones.Comment: 25 pages (including cover pages), 9 figures, 1 table, accepted by Icarus DI Special Issu

A search for periodic and quasi-periodic photometric behavior in the cataclysmic variable TT arietis

Observations of TT Ari obtained at 11 observatories (campaign TT Ari-94) during 258 hr were carried out to study optical variability on timescales from minutes to weeks. The best-fit primary photometric period determined from 16 nights of data obtained at the Dushak-Eregdag station of the Odessa State University is P = 0d.133160 ± 0d.000004 with a mean amplitude of 0.0513 ± 0.0008 mag. This new primary photometric period is larger than that obtained during the TT Ari-88 campaign and is well outside the range of estimates published since 1961. Contrary to previous findings, the "5-7 hr" secondary photometric period is not seen. Our observations do show evidence for periods of 2d.916 and 0d.3040 with amplitudes of 43 and 25 mmag, respectively. The beat period between the spectroscopic and photometric periods is not seen. No coherent oscillations in the range f = 10-2500 cycles day-1 are found. The highest peaks in the power spectrum cover the wide range of 24-139 cycles day-1. In the mean periodogram, the highest peak corresponds to 21 and 30 minutes for the largest sets of observations, i.e., those obtained at Odessa and Krakow Universities, respectively. In the instrumental B system, variations with an amplitude exceeding 0.011 mag occur 8 times (from 33 runs) at 24 minutes. We conclude that quasi-periodic variations occur at a few preferred timescales rather than at a relatively stable period with a secular decrease. In the frequency range 90-900 cycles day-1, the power spectrum obeys a power law with a slope ranging from γ = 1.3 to 2.6 for different runs

M31N 2008-12a - the remarkable recurrent nova in M31: Pan-chromatic observations of the 2015 eruption

The Andromeda Galaxy recurrent nova M31N 2008-12a had been observed in eruption ten times, including yearly eruptions from 2008-2014. With a measured recurrence period of $P_\mathrm{rec}=351\pm13$ days (we believe the true value to be half of this) and a white dwarf very close to the Chandrasekhar limit, M31N 2008-12a has become the leading pre-explosion supernova type Ia progenitor candidate. Following multi-wavelength follow-up observations of the 2013 and 2014 eruptions, we initiated a campaign to ensure early detection of the predicted 2015 eruption, which triggered ambitious ground and space-based follow-up programs. In this paper we present the 2015 detection; visible to near-infrared photometry and visible spectroscopy; and ultraviolet and X-ray observations from the Swift observatory. The LCOGT 2m (Hawaii) discovered the 2015 eruption, estimated to have commenced at Aug. $28.28\pm0.12$ UT. The 2013-2015 eruptions are remarkably similar at all wavelengths. New early spectroscopic observations reveal short-lived emission from material with velocities $\sim13000$ km s$^{-1}$, possibly collimated outflows. Photometric and spectroscopic observations of the eruption provide strong evidence supporting a red giant donor. An apparently stochastic variability during the early super-soft X-ray phase was comparable in amplitude and duration to past eruptions, but the 2013 and 2015 eruptions show evidence of a brief flux dip during this phase. The multi-eruption Swift/XRT spectra show tentative evidence of high-ionization emission lines above a high-temperature continuum. Following Henze et al. (2015a), the updated recurrence period based on all known eruptions is $P_\mathrm{rec}=174\pm10$ d, and we expect the next eruption of M31N 2008-12a to occur around mid-Sep. 2016

Metrological Challenges of Synchrotron Radiation Optics

Modern third generation storage rings, require state-of-the-art grazing incidence x-ray optics, in order to monochromate the Synchrotrons Radiation (SR) source photons, and focus them into the experimental stations. Slope error tolerances in the order of 0.5 {micro}Rad RMS, and surface roughness well below 5 {angstrom} RMS, are frequently specified for mirrors and gratings exceeding 300 mm in length. Non-contact scanning instruments were developed, in order to characterize SR optical surfaces, of spherical and aspherical shape. Among these, the Long Trace Profiler (LTP), a double pencil slope measuring interferometer, has proved to be particularly reliable, and was adopted by several SR optics metrology laboratories. The ELETTRA soft x-rays and optics metrology laboratory, has operated an LTP since 1992. We review the basic operating principles of this instrument, and some major instrumental and environmental improvements, that were developed in order to detect slope errors lower than 1 {micro}Rad RMS on optical surfaces up to one metre in length. A comparison among measurements made on the same reference flat, by different interferometers (most of them were LTPs) can give some helpful indications in order to optimize the quality of measurement

I sistemi contabili universitari come strumenti di monitoraggio dell’economicità: un’evoluzione possibile?

Anche per le università pubbliche, come per agli altri tipi di aziende, l'economicità dipende congiuntamente dalle performance dell’ateneo e dal rispetto delle condizioni di equilibrio che consentono il suo funzionamento. Il lavoro esamina il ruolo che i diversi sistemi contabili delle università, alla luce delle specificità del suo contesto, possono svolgere: – nella misurazione dell’efficacia e dell’efficienza, con riferimento sia all’attività istituzionale che alle eventuali attività profit oriented; – nella valutazione della capacità di mantenere condizioni di equilibrio economico, patrimoniale, finanziario e monetario. Lo studio viene sviluppato considerando l’evoluzione finora compiuta dai sistemi contabili universitari sia per quanto riguarda l’oggetto di rappresentazione (contabilità generale - contabilità analitica) che con riferimento al profilo di indagine (contabilità finanziaria - contabilità economico patrimoniale), evidenziando pregi e difetti delle possibili configurazioni alternative. Nelle conclusioni vengono delineate le caratteristiche del sistema di contabilità direzionale (sistema di contabilità economico-patrimoniale, volto alla redazione di un unico bilancio per l’intero ateneo, integrato con la strumentazione tipica del controllo di gestione ed in particolare con la contabilità analitica e il budget) verso cui si ritiene debba evolversi il sistema contabile delle università per poter svolgere efficacemente il monitoraggio dell’economicità

I sistemi contabili universitari come strumenti di monitoraggio dell’economicità: un’evoluzione possibile?

Anche per le università pubbliche, come per agli altri tipi di aziende, l'economicità dipende congiuntamente dalle performance dell’ateneo e dal rispetto delle condizioni di equilibrio che consentono il suo funzionamento. Il lavoro esamina il ruolo che i diversi sistemi contabili delle università, alla luce delle specificità del suo contesto, possono svolgere: – nella misurazione dell’efficacia e dell’efficienza, con riferimento sia all’attività istituzionale che alle eventuali attività profit oriented; – nella valutazione della capacità di mantenere condizioni di equilibrio economico, patrimoniale, finanziario e monetario. Lo studio viene sviluppato considerando l’evoluzione finora compiuta dai sistemi contabili universitari sia per quanto riguarda l’oggetto di rappresentazione (contabilità generale - contabilità analitica) che con riferimento al profilo di indagine (contabilità finanziaria - contabilità economico patrimoniale), evidenziando pregi e difetti delle possibili configurazioni alternative. Nelle conclusioni vengono delineate le caratteristiche del sistema di contabilità direzionale (sistema di contabilità economico-patrimoniale, volto alla redazione di un unico bilancio per l’intero ateneo, integrato con la strumentazione tipica del controllo di gestione ed in particolare con la contabilità analitica e il budget) verso cui si ritiene debba evolversi il sistema contabile delle università per poter svolgere efficacemente il monitoraggio dell’economicità