100 research outputs found

    Measurement results and improvements on an open EPR system

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    Electron spin resonance (ESR) is a spectroscopic method that allows to measure stable radicals induced by ionizing radiation. The EPR measurements can help to estimate the dose absorbed by people exposed during a nuclear disaster, detecting the number of radicals induced in their mobile phones due to the exposition [1]. Using conventional closed microwave cavities, the phone display must be fragmented in order to be introduced inside the resonator, becoming no more usable. The aim of this work is to develop a system, compatible with the spectrometer Bruker Elexys E500, able to preserve the sample integrity. The system uses an X-band resonant metallic cavity with a slit, realized on one side, for the leak of the excitation magnetic field and a Helmotz coil pair. The resonator allows measuring a sample lodged outside the cavity, while the coils produce a 100 kHz modulated field that encodes the output signal at a particular frequency and increases the SNR

    The Extreme Energy Events HECR array: status and perspectives

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    The Extreme Energy Events Project is a synchronous sparse array of 52 tracking detectors for studying High Energy Cosmic Rays (HECR) and Cosmic Rays-related phenomena. The observatory is also meant to address Long Distance Correlation (LDC) phenomena: the network is deployed over a broad area covering 10 degrees in latitude and 11 in longitude. An overview of a set of preliminary results is given, extending from the study of local muon flux dependance on solar activity to the investigation of the upward-going component of muon flux traversing the EEE stations; from the search for anisotropies at the sub-TeV scale to the hints for observations of km-scale Extensive Air Shower (EAS).Comment: XXV ECRS 2016 Proceedings - eConf C16-09-04.

    U-PHOS Project: Development of a Large Diameter Pulsating Heat Pipe Experiment on board REXUS 22

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    U-PHOS Project aims to analyse and characterise the behaviour of a large diameter Pulsating Heat Pipe (PHP) on board REXUS 22 sounding rocket. A PHP is a passive thermal control device consisting of a serpentine capillary tube, evacuated, partially filled with a working fluid and finally sealed. In this configuration, the liquid and vapour phases are randomly distributed in the form of liquid slugs and vapour plugs. The heat is efficiently transported by means of the self-sustained oscillatory fluid motion driven by the phase change phenomena. On ground conditions, a small diameter is required in order to obtain a confined slug flow regime. In milli-gravity conditions, buoyancy forces become less intense and the PHP diameter may be increased still maintaining the slug/plug flow configuration typical of the PHP operation. Consequently, the PHP heat power capability may be increased too. U-PHOS aims at proving that a Large Diameter PHP effectively works in milli-g conditions by characterizing its thermal response during a sounding rocket flight. The actual PHP tube is made of aluminum (3 mm inner diameter, filled with FC-72), heated at the evaporator by a compact electrical resistance, cooled at the condenser by a Phase Change Material (PCM) embedded in a metallic foam. The tube wall temperatures are recorded by means of Fibre Bragg Grating (FBG) sensors; the local fluid pressure is acquired by means of a pressure transducer. The present work intends to report the actual status of the project, focusing in particular on the experiment improvements with respect to the previous campaign

    Upgraded Pulsating Heat Pipe Only For Space (U-Phos): Results of the 22nd Rexus Sounding Rocket Campaign

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    A large tube may still behave, to a certain extent, as a capillary in a micro-gravity environment. This very basic concept is here applied to a two-phase passive heat transfer devices in order to obtain a new family of hybrid wickless heat pipes. Indeed, a Loop Thermosyphon, which usually consists of a large tube, closed end to end in a loop, evacuated and partially filled with a working fluid and intrinsically gravity assisted, may become a capillary tube in space condition and turn its thermo-fluidic behavior into a so called Pulsating Heat Pipe (PHP), or better, a Space Pulsating Heat Pipe (SPHP). Since the objective of the present work is to experimentally demonstrate the feasibility of such a hybrid device, a SPHP has been designed, built, instrumented and tested both on ground and microgravity conditions on the 22nd ESA REXUS Sounding Rocket Campaign. Ground tests demonstrate that the device effectively work as a gravity assisted loop thermosyphon, whether the sounding rocket data clearly reveal a change in the thermal hydraulic behavior very similar to the PHP. Since a microgravity period of approximately 120s is not sufficient to reach a pseudo steady state regime, further investigation on a longer term weightless condition is mandatory

    Uncertainty on radiation doses estimated by biological and retrospective physical methods

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    Biological and physical retrospective dosimetry are recognised as key techniques to provide individual estimates of dose following unplanned exposures to ionising radiation. Whilst there has been a relatively large amount of recent development in the biological and physical procedures, development of statistical analysis techniques has failed to keep pace. The aim of this paper is to review the current state of the art in uncertainty analysis techniques across the ‘EURADOS Working Group 10— Retrospective dosimetry’ members, to give concrete examples of implementation of the techniques recommended in the international standards, and to further promote the use of Monte Carlo techniques to support characterisation of uncertainties. It is concluded that sufficient techniques are available and in use by most laboratories for acute, whole body exposures to highly penetrating radiation, but further work will be required to ensure that statistical analysis is always wholly sufficient for the more complex exposure scenarios

    !CHAOS: A cloud of controls

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    The paper is aimed to present the !CHAOS open source project aimed to develop a prototype of a national private Cloud Computing infrastructure, devoted to accelerator control systems and large experiments of High Energy Physics (HEP). The !CHAOS project has been financed by MIUR (Italian Ministry of Research and Education) and aims to develop a new concept of control system and data acquisition framework by providing, with a high level of abstraction, all the services needed for controlling and managing a large scientific, or non-scientific, infrastructure. A beta version of the !CHAOS infrastructure will be released at the end of December 2015 and will run on private Cloud infrastructures based on OpenStack
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