Detection of the Cherenkov light diffused by Sea Water with the ULTRA Experiment

The study of Ultra High Energy Cosmic Rays represents one of the most challenging topic in the Cosmic Rays and in the Astroparticle Physics fields. The interaction of primary particles with atmospheric nuclei produces a huge Extensive Air Shower together with isotropic emission of UV fluorescence light and highly directional Cherenkov photons, that are reflected/diffused isotropically by the impact on the Earth's surface or on high optical depth clouds. For space-based observations, detecting the reflected Cherenkov signal in a delayed coincidence with the fluorescence light improves the accuracy of the shower reconstruction in space and in particular the measurement of the shower maximum, giving a strong signature for discriminating hadrons and neutrinos, and helping to estimate the primary chemical composition. Since the Earth's surface is mostly covered by water, the ULTRA (UV Light Transmission and Reflection in the Atmosphere)experiment has been designed to provide the diffusing properties of sea water, overcoming the lack of information in this specific field. A small EAS array, made up of 5 particle detectors, and an UV optical device, have been coupled to detect in coincidence both electromagnetic and UV components. The detector was in operation from May to December, 2005, in a small private harbor in Capo Granitola (Italy); the results of these measurements in terms of diffusion coefficient and threshold energy are presented here.Comment: 4 pages, 3 figures, PDF format, Proceedings of 30th ICRC, International Cosmic Ray Conference 2007, Merida, Yucatan, Mexico, 3-11 July 200

Extreme Energy Cosmic Rays (EECR) Observation Capabilities of an "Airwatch from Space'' Mission

The longitudinal development and other characteristics of the EECR induced atmospheric showers can be studied from space by detecting the fluorescence light induced in the atmospheric nitrogen. According to the Airwatch concept a single fast detector can be used for measuring both intensity and time development of the streak of fluorescence light produced by the atmospheric shower induced by an EECR. In the present communication the detection capabilities for the EECR observation from space are discussed.Comment: 3 pages (LaTeX). To appear in the Proceedings of TAUP'9

The EUSO simulation and analysis framework

ESAF is the simulation and analysis software framework developed for the EUSO experiment. ESAF's scope is the whole process of data simulations and data-analysis, from the primary particle interaction in atmosphere to the reconstruction of the event. Based on the ROOT package and designed using Object Oriented technology, ESAF is organized in two main programs: the full montecarlo simulation and the reconstruction framework. The former includes all the relevant physical contributions, shower development in atmosphere, light transport to the detector pupil and detector response, while the latter comprises basic data cleaning, track direction, shower profile and energy reconstruction algorithms. Here we describe the software architecture and its main features

The Role of Eye Gaze in Subjective Decision Making

Shimojo, Simion, Shimojo and Scheier (2003) provided preliminary evidence that eye movements have an active role in preference formation. In their study, subjects were presented with two faces and chose which was more attractive. By manipulating how long subjects were able to look at each face after an eye movement, Shimojo et al. (2003) showed that faces presented for a longer duration were more likely to be chosen as more attractive. However, a recent study from Nittono and Wada (2009) showed that an eye movement may not be necessary for this effect, as novel graphic patterns presented in the centre of the screen (thus requiring no eye movements) for longer durations were also more likely to be preferred. The purpose of the current study was to further investigate whether eye movements do have an active role in preference formation. The present study used the same paradigm as Shimojo et al.’s (2003) study. Subjects in Experiment 1 were presented with images of two real faces, alternatively (one for 900ms, one for 300ms) for six repetitions. There were 3 independent experimental conditions. One group were required to make eye movements to laterally presented faces and judge attractiveness (lateral attractiveness condition), a second were not required to make eye movements to centrally presented faces and judge attractiveness (central attractiveness condition). The third were required to make eye movements to laterally presented faces and judge roundness (lateral roundness condition). The findings indicated that subjects were more likely to choose the longer presented faces in the lateral attractiveness and central attractiveness conditions, but not the lateral roundness conditions. Experiment 2 was similar to Experiment 1 with the exception of the type of stimuli, which consisted of computer generated faces (CGFs). Subjects were more likely to choose the longer presented CGF in the lateral attractiveness, central attractiveness and lateral roundness conditions. The findings of the present study were not in line with Shimojo et al.’s (2003) previous findings, who found that faces presented for a longer duration were only preferred in the lateral attractiveness condition of their study. It is possible that the faces that are presented for the longer duration in the current paradigm are preferred due to the increase in exposure duration irrespective of an eye movement (as per the findings from Nittono and Wada, 2009). As it is unclear as to whether eye movements play an active role in preference formation, the findings of the present study have not been able to contribute to computational models of decision making

Results from the ULTRA experiment in the framework of the EUSO project

The detection of Cerenkov light from EAS in a delayed coincidence with fluorescence light gives a strong signature to discriminate protons and neutrinos in cosmic rays. For this purpose, the ULTRA experiment has been designed with 2 detectors: a small EAS array (ETscope) and an UV optical device including wide field (Belenos) and narrow field (UVscope) Cerenkov light detectors. The array measures the shower size and the arrival direction of the incoming EAS, while the UV devices, pointing both to zenith and nadir, are used to determine the amount of direct and diffused coincident Cerenkov light. This information, provided for different diffusing surfaces, will be used to verify the possibility of detecting from Space the Cerenkov light produced by UHECRs with the EUSO experiment, on board the ISS

Observation of CR Anisotropy with ARGO-YBJ

The measurement of the anisotropies of cosmic ray arrival direction provides important informations on the propagation mechanisms and on the identification of their sources. In this paper we report the observation of anisotropy regions at different angular scales. In particular, the observation of a possible anisotropy on scales between $\sim$ 10 $^{\circ}$ and $\sim$ 30 $^{\circ}$ suggests the presence of unknown features of the magnetic fields the charged cosmic rays propagate through, as well as potential contributions of nearby sources to the total flux of cosmic rays. Evidence of new weaker few-degree excesses throughout the sky region $195^{\circ}\leq$ R.A. $\leq 315^{\circ}$ is reported for the first time.Comment: Talk given at 12th TAUP Conference 2011, 5-9 September 2011, Munich, German

Dimethyl ether as a drift-chamber gas

We have continued the testing of dimethyl ether as a drift-chamber gas in order to improve the understanding of its properties. In particular, we report on measurement accuracy, on systematic effects, and some preliminary data on the ageing of a detector filled with dimethyl ether.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26012/1/0000079.pd

Measurement of the antiproton/proton ratio in the few-TeV energy range with ARGO-YBJ

Cosmic ray antiprotons provide an important probe for the study of cosmic ray propagation in the interstellar space and to investigate the existence of Galactic dark matter. The ARGO-YBJ experiment is observing the Moon shadow with high statistical significance at an energy threshold of a few hundred GeV. Using all the data collected until November 2009, we set two upper limits on the antip/p flux ratio: 5% at an energy of 1.4 TeV and 6% at 5 TeV with a confidence level of 90%. In the few-TeV range the ARGO-YBJ results are the lowest available, useful to constrain models for antiproton production in antimatter domains.Comment: Talk given at the CRIS 2010 Conference, September 2010, Catania - Italy, 6 page