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The PADME charged particle detector system should detect positrons and electrons with efficiency better than 99 {\%} and time resolution below 1 ns. The system hosts about 200 readout electronics channels whose operation has to be verified and commissioned. A custom based test system allowing to perform qualitative check of the produced frontend electronics has been developed and was used to test a total of 256 channels. The obtained time resolution was found to be consistent with the requirements and better than 500 ps for all the channels.

The PADME experiment at the Laboratori Nazionali di Frascati of the INFN searches for a hypothetical dark photon A ′ , produced in the annihilation between a positron of a beam with an electron of a target. The target is an active component of the experiment; it consists of a thin and large size diamond detector with a pattern of graphitic strips on both sides acting as ohmic electrodes for detector polarization and signal readout. In this paper the operation and performance of the active diamond target, as observed in the first PADME physics run, are reported.

One of the goals of the AIRFLY (AIR FLuorescence Yield) experiment is to measure the absolute fluorescence yield induced by electrons in air to better than 10% precision. We introduce a new technique for measurement of the absolute fluorescence yield of the 337 nm line that has the advantage of reducing the systematic uncertainty due to the detector calibration. The principle is to compare the measured fluorescence yield to a well known process - the Cerenkov emission. Preliminary measurements taken in the BFT (Beam Test Facility) in Frascati, Italy with 350 MeV electrons are presented. Beam tests in the Argonne Wakefield Accelerator at the Argonne National Laboratory, USA with 14 MeV electrons have also shown that this technique can be applied at lower energies., presented at the 5th Fluorescence Workshop, El Escorial - Madrid, Spain, 16 - 20 September 2007

The Italian institute for nuclear physics (INFN) has financed the SIMP project (2019-2021) in order to strengthen its skills and technologies in the field of meV detectors with the ultimate aim of developing a single microwave photon detector. This goal will be pursued by improving the sensitivity and the dark count rate of two types of photodetectors: current biased Josephson Junction (JJ) for the frequency range 10-50 GHz and Transition Edge Sensor (TES) for the frequency range 30-100 GHz. Preliminary results on materials and devices characterization are presented., Comment: 7 pages, 4 figures

In this paper, a two-dimensional numerical investigation on a prototypal solar chimney system integrated with an absorbing capacity wall in a south facade of a building is presented. The capacity wall is composed of a high absorbing plate and an assigned thickness of phase change material. The chimney consists of a converging channel with one vertical absorbing wall and the glass plate inclined of 2°. The chimney is 5.0 m high, with the channel height equal to 4.0 m, whereas the channel gap is at the inlet equal to 0.34 m and at the outlet it is 0.20 m. The thermal energy storage system is 4.0 m high with a paraffin wax. The transient analysis on a two-dimensional model in airflow is carried out and the governing equations for natural convection in turbulent flow with Boussinesq assumption and thermophysical properties temperature independent are given in terms of k-ε turbulence model. The problem is solved by means of the commercial code Ansys-Fluent using the finite volume method. The numerical analysis was intended to evaluate the thermal and fluid dynamic behavior of the solar chimney integrated with a latent thermal energy storage system for different values of the PCM thickness. The analysis is accomplished at the 21 June by the sunrise to sunset with the chimney oriented towards south. The simulations are performed considering the solar chimney located in Aversa, Italy. Results are given in terms of wall temperature distributions, air velocity and temperature fields and transversal profiles in the channel whereas in terms of liquid fractions, temperature and stream function fields for the phase change material. Thermal and fluid dynamics behaviors are evaluated in order to have some indications to improve the energy conversion system.

Nanofluids are obtained by dispersing nanoparticles and dispersant, when present, in a base fluid. Their properties, in particular their stability, however, are strictly related to several other parameters, knowledge of which is important to reproduce the nanofluids and correctly interpret their behavior. Due to this complexity, the results appear to be frequently unreliable, contradictory, not comparable and/or not repeatable, in particular for the scarcity of information on their preparation. Thus, it is essential to define what is the minimum amount of information necessary to fully describe the nanofluid, so as to ensure the possibility of reproduction of both their formulation and the measurements of their properties. In this paper, a literature analysis is performed to highlight what are the most important parameters necessary to describe the configuration of each nanofluid and their influence on the nanofluid’s properties. A case study is discussed, analyzing the information reported and the results obtained for the thermophysical properties of nanofluids formed by water and TiO2 nanoparticles. The aim is to highlight the differences in the amount of information given by the different authors and exemplify how results can be contradictory. A final discussion gives some suggestions on the minimum amount of information that should be given on a nanofluid to have the possibility to compare results obtained for similar nanofluids and to reproduce the same nanofluid in other laboratories.

In this paper a numerical investigation has been accomplished to study the thermal and fluid dynamic behavior of a tubular heat exchanger partially filled with metal foam. The Darcy – Brinkman - Forchheimer model and the local thermal non-equilibrium hypothesis (LTNE) for the thermal energy are used to execute two-dimensional analyses on the aluminum foam heat exchanger. The heat exchanger is studied for several air flow rates and a fixed temperature on the surface tube. The results are shown in terms of heat transfer rate and pumping power. Furthermore, the ratios in terms of heat transfer rate and pumping power are given for the two different configurations (partially and totally filled) in order to find the most convenient scheme. Furthermore, the temperature and pressure fields are evaluated. a comparison among the different thickness of the metal foam between two adjacent tubes and the fully filled configuration is given. The results show that the smaller value of metal foam thickness is characterized by a better performance.

Josephson junctions, in appropriate configurations, can be excellent candidates for detection of single photons in the microwave frequency band. Such possibility has been recently addressed in the framework of galactic axion detection. Here are reported recent developments in the modelling and simulation of dynamic behaviour of a Josephson junction single microwave photon detector. For a Josephson junction to be enough sensitive, small critical currents and operating temperatures of the order of ten of mK are necessary. Thermal and quantum tunnelling out of the zero-voltage state can also mask the detection process. Axion detection would require dark count rates in the order of 0.001 Hz. It is, therefore, is of paramount importance to identify proper device fabrication parameters and junction operation point., Comment: 7 pages, 9 figures

In the present paper a two-dimensional convective heat transfer problem in a partially filled channel with metal foam is numerically solved in steady state regime. An external thermoelectric generators (TEG) component is placed on the top surface of the channel. The numerical analyses are accomplished assuming the local thermal equilibrium (LTE) model to simulate the presence of the aluminum foam. The working fluid is exhaust gas with properties equal to the air for fixed temperature of the upper surface of the thermo-electric generator (TEG). The thermophysical properties are assumed temperature independent and the TEG component is considered as a solid with an internal energy generation. The Ansys-Fluent code is applied in order to resolve the governing equations for gas, porous media and TEG. Several mass flow rates of exhaust gas on the inlet section of the channel are considered. Different thicknesses of aluminum foam are assumed into the duct. The foam is characterized by different porosity equal to 0.90, 0.95, 0.97. Moreover, the number of pores per inch also changes and assumes the following values of 5, 20, 40. Results are showed in terms of temperature distributions, pressure drop, thermoelectric efficiency for different exhaust gas flow rates and metal foam characteristics and thicknesses. The results highlight that the use of metal foams significantly increases the heat transfer between the surface of exhaust gas tube and hot gas. Consequently, the effectiveness improves, and it increases between three-ten times with respect to the one for tube without metal foams. It is shown that the pore density does not affect the effectiveness.

Thermal storage system (TES) with phase change material (PCM) is an important device to store thermal energy. It works such a thermal buffer to reconcile the supply energy with the energy demand. It has a wide application field especially for solar thermal energy storage. The main drawback is the low value of thermal conductivity of the PCM making the system useless for the thermal engineering applications. A way to resolve this problem is to combine the PCM with a highly conductive material like metal foam and/or nanoparticles. In this paper a numerical investigation on the metal foam effects into the latent heat thermal energy storage system, based on a phase change material with nanoparticles (Nano-PCM), is accomplished. The modelled TES is a typical 70L water tank filled up with Nano-PCM with pipes to transfer thermal energy from a fluid to the Nano-PCM. The PCM is a pure paraffin wax and the nanoparticles are in aluminum oxide. The metal foam is made of aluminum with assigned values of porosity. The enthalpy-porosity theory is employed to simulate the phase change of the Nano-PCM and the metal foam is modelled as a porous media. Numerical simulations are carried out using the Ansys-Fluent code. The results are shown in term of melting time, temperature at varying of time and total amount of stored energy.

Solar chimney is a system to produce energy and it has several applications, such as production of electricity, buildings ventilation, heating and cooling. In this paper, a numerical investigation on a prototypal solar chimney system integrated in a south facade of a building is presented. The chimney is 4.0 m high, 1.5 m wide whereas the thickness at the inlet the channel has a gap equal to 0.34 m and at the outlet it is 0.20 m. The chimney consists of a converging channel with one vertical wall and one inclined of 2°. The analysis is carried out on a three-dimensional model in airflow and the governing equations are given in terms of k-ε turbulence model. The problem is solved by means of the commercial code Ansys-Fluent. Simulations are carried out considering the solar irradiance for assigned geographical location and for a daily distribution. Further, comparison between steady state and transient regimes is examined and discussed. Results are given in terms of wall temperature distributions, air velocity and temperature fields and transversal profiles. Performances are better when heat flux is higher and sun is in front of chimney and a low-emissivity glass improves solar chimney achievements. Analysis in transient regimes confirm results obtained in steady state regime.

A numerical investigation on the effects of the metal foam into the Latent Heat Thermal Energy Storage System, based on a phase change material, is accomplished. The geometry of the system is a rectangular box heated from below. The PCM is completely embedded in the rectangular box, it is pure paraffin wax with a low value of thermal conductivity and it melts in a range of temperatures. The metal foam is made of copper and it partially fills the rectangular box in order to understand the optimal filling ratio of the foam to have the better thermal performance. The enthalpy-porosity theory is employed to simulate the phase change of the PCM and the metal foam is modelled as a porous media that follow the Brinkman-extended Darcy model. The results are shown in term of melting time, temperature and energy at varying of time or at varying the filling height ratio.

Solar energy is an important renewable energy source that is increasingly used. One of the main drawbacks in the solar energy application is its working periodic time. Thermal Energy Storage (TES) can improve the efficient use and provision of thermal energy whenever there is a mismatch between energy generation and use. Various subsets of TES processes have been investigated and developed for heating and cooling of buildings, industrial applications, and utility and space power systems. The amount of energy input to TES by a sensible heat device is proportional to the difference between the storage final and initial temperatures, the mass of storage medium and its heat capacity. In this paper a high temperature TES is numerically investigated, and a parametric analysis is accomplished. In the formulation of the model it is assumed that the system geometry is cylindrical, the fluid thermophysical properties are dependent on temperature, the effect of gravity is neglected. Air is employed as the heat-carrying fluid and the solid elements, which are minichannels, are made of Cordierite. The system is a honeycomb structure made of parallel triangular channels. The Fluent code is used to solve the governing equations in transient regime. Numerical simulations are carried out with storage medium at different mass flow rates of the heat-carrying fluid and different number of channels for unit of length. Results show the effects of storage medium, mass flow rate on stored thermal energy and storage time. Results in terms of temperature as function of time are presented.

We realized a narrative review of the current literature starting from the case of a patient with raised CA15-3 during an uncomplicated pregnancy after breast cancer. The aim of our paper was to assess specificity, physiological changes and clinical utility of CA 15-3 monitoring during pregnancy after breast cancer, starting from clinical practice and retrieving the most relevant evidence in the literature.

Electric cars, in addition to representing an ecological solution for the serious problems of climate pollution due to the use of fossil fuels, can also represent a turning point in terms of renewal for the world economy with a product that in a short future will become a standard in all the advanced economies of the globe. One of the main problems of electric cars is given by the thermal control of their batteries, since, below and above a certain temperature range and also with the use of the air conditioning, they abruptly decrease the autonomy of the vehicle, creating inconvenience to the owners of such cars. The thermal control of lithium batteries for electric cars must therefore take into account both the problems of thermal increase due to the functioning of the battery itself, and the climatic conditions outside the vehicle which impact, if above a certain range, negatively on the performance of the automobile, decreasing both the autonomy and the battery life. In this study, an attempt is made to control both thermal aspects by trying to thermally isolate the battery from the vehicle’s external climate and by trying to control the temperature peaks due to the operation of the battery itself. For this purpose, in this study a two-dimensional model is considered to investigate numerically the thermal control of a lithium battery of a commercial electric car. The battery has the size of 8 cm x 31 cm x 67 cm and its capacity is equal to 232 Ah with 5.3 kWh. The thermal control is realized by means one internal layer of copper foam and paraffin, placed around the battery, and a more external paraffin layer. The external surfaces are cooled by an air flow. The governing equations are solved by finite volume method using the commercial code Ansys-Fluent. Different cases are simulated for different thickness of the two layers and air flow velocity. The results, carried out for metal foam with different PPIs and porosities, are given in terms of temperature and liquid fraction fields, heat transfer behaviors such as surface temperature profiles as a function of time and temperature distributions along the external surface of battery for the different cases.

Numerical simulation of nanofluid flows is of maximum importance for a large area of applications, especially in the solar energy technology. Even though a lot of numerical studies are available in the open literature, there is still a large debate in regard to the most appropriate approach when dealing with nanofluids. Plus, a precise simulation of the thermal fluid-solid system encompasses a profound understanding of the fundamental physical phenomena that appear in the nanofluid flow. In this idea, a number of simplifications and approaches are considered, and the aim of this benchmark study is to shed some light in the most suitable CFD approach when dealing with nanofluid flow. Finally, different approaches were considered by different research groups with relevant experience in CFD and are discussed accordingly and in connection with an experimental case that was chosen as a comparison. The current benchmark study was projected to be an ample reference for investigators interested in dealing with the numerical study of the nanofluids’ flow.

A computational investigation on thermal energy storage system using Phase Change Material (PCM) is accomplished. The system is a honeycomb structure made of parallel triangular channels and half of them are filled with PCM and the others are passed through by the working fluid. Various configurations for different Channels Per Unit of length (CPU) are investigated. A comparison between a direct model and a porous medium model is carried out. The porous medium is modelled with the Darcy law and to evaluate the heat transfer among solid, PCM and air and the local thermal equilibrium assumption is employed. Permeability, inertial resistant coefficient, effective thermal conductivity and interfacial heat transfer coefficient of the equivalent porous medium are evaluated by means of the direct model. Numerical simulations are carried out using the Ansys-Fluent code for the direct model with triangular channels and equivalent porous medium. Results in terms of melting time, fraction liquid and temperature fields as function of time are presented and a comparison between the two models is accomplished.

AGILE is a mission of the Italian Space Agency (ASI) Scientific Program dedicated to gamma-ray astrophysics, operating in a low Earth orbit since April 23, 2007. It is designed to be a very light and compact instrument, capable of simultaneously detecting and imaging photons in the 18 keV to 60 keV X-ray energy band and in the 30 MeV{50 GeV gamma-ray energy with a good angular resolution (< 1 deg at 1 GeV). The core of the instrument is the Silicon Tracker complemented with a CsI calorimeter and a AntiCoincidence system forming the Gamma Ray Imaging Detector (GRID). Before launch, the GRID needed on-ground calibration with a tagged gamma-ray beam to estimate its performance and validate the Monte Carlo simulation. The GRID was calibrated using a tagged gamma-ray beam with energy up to 500 MeV at the Beam Test Facilities at the INFN Laboratori Nazionali di Frascati. These data are used to validate a GEANT3 based simulation by comparing the data and the Monte Carlo simulation by measuring the angular and energy resolutions. The GRID angular and energy resolutions obtained using the beam agree well with the Monte Carlo simulation. Therefore the simulation can be used to simulate the same performance on-light with high reliability., 19 page 12 figures

In the present work a computational investigation of transient thermal control device using Phase Change Material (PCM) is accomplished. The system is a honeycomb solid checkerboard matrix filled with Phase Change Material. The honeycomb is set of different parallel squared channels and half of them are filled with PCM and the others are passed through by the working fluid. Various configurations are investigated for different channels per unit of length (CPL), different heat fluxes and inlet velocities. A comparison between the direct honeycomb model and a porous medium model is made. The porous medium is modelled with the extended Darcy-Brinkman law and to evaluate the heat exchange between the solid and the fluid zones a Local-Thermal Non-Equilibrium assumption is used. By the results of the direct honeycomb model the characteristics such as permeability, inertial resistant coefficient, effective thermal conductivity and interfacial heat transfer are evaluated and then compare with the porous medium model. The analysis have the aim of estimate an optimized configuration in term of channels per unit of length (CPL) as a balance between pressure drop and heat transfer rate inside the honeycomb system. Numerical simulations were carried out using the Ansys-Fluent 15.0 code. Results in terms of melting time, temperature fields, stored energy as function of time are presented for the charging and discharging phase.

In the present investigation a simplified analysis is accomplished to handle a parallel plate system with parallel channels as a porous media and to evaluate the permeability, inertia coefficient, the interfacial heat transfer coefficient between solid matrix and fluid and the specific area for the equivalent porous medium. In the local heat transfer coefficient is also considered the radiative heat transfer which will be temperature dependent. The evaluation of these two terms will be carried out numerically by the Ansys-Fluent code to compare the simplified and numerical model results. The analysis should allow the estimation of an optimized configuration, in terms of number of pore per inch (PPI) or channels per unit of length (CPL), as a balance between pressure drop and heat transfer rate inside the parallel plates configuration. Results show the effects of storage medium, different porosity values, porosity effect and mass flow rate on stored thermal energy and storage time. Results in terms of stored thermal energy as function of time are presented. Moreover, the behavior related to fluid pressure losses and internal heat transfer is analyzed.

Thermal storage system (TES) with phase change material (PCM) is an important device to store thermal energy. It works as a thermal buffer to reconcile the supply energy with the energy demand. It has a wide application field, especially for solar thermal energy storage. The main drawback is the low value of thermal conductivity of the PCM making the system useless for thermal engineering applications. A way to resolve this problem is to combine the PCM with a highly conductive material like metal foam and/or nanoparticles. In this paper a numerical investigation on the metal foam effects in a latent heat thermal energy storage system, based on a phase change material with nanoparticles (nano-PCM), is accomplished. The modelled TES is a typical 70 L water tank filled with nano-PCM with pipes to transfer thermal energy from a fluid to the nano-PCM. The PCM is a pure paraffin wax and the nanoparticles are in aluminum oxide. The metal foam is made of aluminum with assigned values of porosity. The enthalpy-porosity theory is employed to simulate the phase change of the nano-PCM and the metal foam is modelled as a porous media. Numerical simulations are carried out using the Ansys Fluent code. The results are shown in terms of melting time, temperature at varying of time, and total amount of stored energy. © 2018 by the authors. Licensee MDPI, Basel, Switzerland.

Solar energy is an important alternative energy source that will likely be utilized in the future. One main limiting factor in the application of solar energy is its cyclic time dependence. Therefore, solar systems require energy storage to provide energy during the night and overcast periods. Although the need of thermal energy storage also exists for many other thermal applications, it is particularly notable for solar applications. It can improve the efficient use and provision of thermal energy whenever there is a mismatch between energy generation and use. In sensible thermal storage, energy is stored by changing the temperature of a storage medium. The amount of energy input to thermal energy storage by a sensible heat device is proportional to the difference between the storage final and initial temperatures, the mass of storage medium and its heat capacity. Each medium and porous matrix has its own advantages and disadvantages.

In this paper a high temperature thermal storage in a honeycomb solid matrix is numerically investigated and a parametric analysis is accomplished. In the formulation of the model it is assumed that the system geometry is cylindrical, the fluid and the solid thermophysical properties are temperature independent and radiative heat transfer is take into account whereas the effect of gravity are neglected. Air is employed as the working fluid and the solid material is cordierite. The evaluation of the fluid and thermal behaviors are accomplished assuming the honeycomb as a porous medium. The Brinkman-Forchheimer-extended Darcy model is used in the governing equations and the local thermal non equilibrium is assumed. The commercial CFD Fluent code is used to solve the governing equations in transient regime. Numerical simulations are carried out with storage medium at different mass flow rates of the working fluid and different porosity values. Results show the effects of storage medium, different porosity values, porosity effect and mass flow rate on stored thermal energy and storage time. Results in terms of temperature profiles and stored thermal energy as function of time are presented.Copyright © 2012 by ASME

A description of transient natural convection in air in a vertical parallel plates channel, with one plate heated and the other one cooled at uniform heat flux, is numerically accomplished. The transient problem is two-dimensional and laminar with constant thermophysical properties. The numerical solution is carried out employing the commercial CFD code Fluent. The computational domain is made up of the physical configuration and two reservoirs, placed downstream and upstream the channel. Results are obtained for Rayleigh number between 103 and 106 and they are presented in terms of wall temperature profiles as a function of time, velocity and temperature profiles along transversal channel sections. The simulation allows to describe the fluid motion structures inside and outside the channel. A complete skew-symmetric motion is detected. For Ra≥105 temperature profiles as a function of time show periodical oscillations. For Ra≥104 overshoots are observed along the profiles and for corresponding average Nusselt number profiles dips are present.

In this paper an experimental investigation on natural convection in air in inclined channels with rectangular transversal section and lower wall heated at uniform heat flux is carried out. Wall temperature measurements and flow visualization are presented. The results allow investigating on the effect of the distance between the two principal parallel walls and of the inclination angle. The experiments are accomplished for two channel gap values: 20 and 40 mm. The inclination angle is equal to 80° and 88°. The flow development and the shape of flow transitions along the channel are visualized. Flow visualization allows to describe the secondary motion inside an inclined channel. Flow separation region along the lower heated plate begins at lower axial coordinate as the wall heat flux, the inclination angle and the channel gap are greater. The flow separation depends also on transversal coordinate. The detected secondary structures pass from thermals to plumes and vortices. Along the plane parallel to the heated wall, the visualization shows that thermal plumes split in V-shaped structures. For the largest considered channel gap value the instability phenomena in the channel are stronger and chaotic motion in the channel outlet zone is observed. When the channel gap value increases wall temperatures become lower because the higher distance between the walls determines a greater mass flow rate and an increase in the heat transfer.