Un alimentatore solare per stazioni remote

Un alimentatore solare può essere un oggetto sofisticato: quello che è stato realizzato dall’LNTS (Laboratori Nuove Tecologie Strumenti, UF Laboratori, Roma1) è una tessera del progetto STRADIUM (ASI), e fa tesoro dell’esperienza acquisita nella progettazione degli alimentatori del progetto PEGASO [Iarocci et al., 2008]. Nato per l’uso in stratosfera, l’alimentatore si presta benissimo all’uso in stazioni geofisiche remote. L’alimentatore accetta tre pannelli solari in ingresso ed utilizza due batterie di elementi Sn-Pb tenendo conto della variazione delle caratteristiche di carica con la temperatura. L’intervallo di temperatura di funzionamento, batterie comprese, va da –50 a + 60°C. La pressione di esercizio va da 1 bar a 5 mbar (dal livello del mare a 35 Km). Questi valori sono stati verificati sul prototipo, batterie comprese, in camera termovuoto. Le pagine che seguono sono quelle del manuale scritto a corredo dell’apparecchio: forniscono una descrizione fedele del principio di funzionamento e del dettaglio tecnico. Le seguenti figure fuori testo illustrano alcune delle fasi di costruzione e verifica del prototipo

Un generatore di impulso ad alta tensione per l'eccitazione di trasduttori piezoelettrici: un metodo per studiare la propagazione delle onde elastiche su campioni di rocce

Il dispositivo qui presentato è stato realizzato per lo studio della propagazione di onde elastiche in campioni di roccia [Wood A. W. Et al. 1955]. Mediante tale tecnica si riescono a determinare alcune caratteristiche fisiche delle rocce. Si tratta di un generatore di impulsi ad alta tensione, necessario per l’eccitazione di trasduttori piezoelettrici. La durata dell’impulso generato è di 1 s, l’ampiezza dell’ordine del kVolt. Il metodo utilizzato per effettuare la misura consiste nell’eccitare il trasduttore in trasmissione con un singolo impulso e quindi misurarne il tempo di volo con il trasduttore di ricezione. Il lavoro, oltre alla descrizione dello strumento, mostra alcuni esperimenti condotti su campioni di alluminio e diversi tipi di roccia. Tali esperimenti si sono resi necessari sia per il collaudo dello strumento che per la messa a punto del metodo

COMPORTAMENTO AD ALTA PRESSIONE DI TRASDUTTORI PIEZOELETTRICI PER APPLICAZIONI DI GEOFISICA SPERIMENTALE

L’investigazione del comportamento acustico di campioni di roccia implica l’uso di trasduttori piezoelettrici [Spinelli et al., 2009], sia in uso attivo (eccitazione e rilevazione) che passivo (rilevazione delle onde elastiche generate da fenomeni di fratturazione). In alcuni casi vengono imposte elevate pressioni per simulare le condizioni di sconfinamento del campione di roccia in profondità, utilizzando un liquido o un gas. La natura dei trasduttori piezoelettrici suggerisce che essi non debbano soffrire molto in ambienti in cui la variazioni di pressione o la pressione di esercizio sia un elemento non trascurabile e possono essere utilizzati in tali condizioni senza particolari precauzioni con evidenti vantaggi nella semplificazione del set-up sperimentale. Questa nota è la descrizione delle misure condotte per caratterizzare dei trasduttori piezoelettrici, nell’intervallo di pressione di interesse (0 - 1000 atm), da utilizzare per scopi sperimentali nell’ambito del progetto europeo ERC Starting Grant Project GLASS InteGrated Laboratories to investigate the mechanics of ASeismic vs. Seismic faulting. Per fare ciò due trasduttori sono stati incollati direttamente tra loro in modo da realizzare un quadripolo, con una porta d’ingresso e una di uscita, e ne è stata rilevata la caratteristica ingresso – uscita al variare della frequenza. Per il rilevamento delle caratteristiche elettriche sono stati usati differenti strumenti di misura: un generatore di segnali, un oscilloscopio e un analizzatore di reti vettoriale. Per imporre sui campioni una pressione controllata è stato allestito un apparato meccanico dedicato, formato da un insieme pistone-cilindro all’interno del quale viene alloggiata la coppia di trasduttori incollati. Nel cilindro viene inserito olio (adeguatamente incomprimibile ed elettricamente isolante) come vettore di pressione; la spinta sul pistone viene esercitata attraverso una pressa idraulica. Una particolare cura è stata posta nella costruzione del passacavo a tenuta per alte pressioni. Nei paragrafi che seguono verranno dapprima descritti i trasduttori usati per gli esperimenti e l’apparato meccanico, quindi si passerà alla presentazione delle misure effettuate in varie condizioni e con i vari strumenti

Muon tracking underground

We present a new design of plastic streamer tubes, optimized to match the experimental requirements of large-area under-ground detectors, where muon identification is needed with good angular resolution

Charged particle's flux measurement from PMMA irradiated by 80 MeV/u carbon ion beam

Hadrontherapy is an emerging technique in cancer therapy that uses beams of charged particles. To meet the improved capability of hadrontherapy in matching the dose release with the cancer position, new dose monitoring techniques need to be developed and introduced into clinical use. The measurement of the fluxes of the secondary particles produced by the hadron beam is of fundamental importance in the design of any dose monitoring device and is eagerly needed to tune Monte Carlo simulations. We report the measurements done with charged secondary particles produced from the interaction of a 80 MeV/u fully stripped carbon ion beam at the INFN Laboratori Nazionali del Sud, Catania, with a Poly-methyl methacrylate target. Charged secondary particles, produced at 90$\degree$ with respect to the beam axis, have been tracked with a drift chamber, while their energy and time of flight has been measured by means of a LYSO scintillator. Secondary protons have been identified exploiting the energy and time of flight information, and their emission region has been reconstructed backtracking from the drift chamber to the target. Moreover a position scan of the target indicates that the reconstructed emission region follows the movement of the expected Bragg peak position. Exploting the reconstruction of the emission region, an accuracy on the Bragg peak determination in the submillimeter range has been obtained. The measured differential production rate for protons produced with $E^{\rm Prod}_{\rm kin} >$ 83 MeV and emitted at 90$\degree$ with respect to the beam line is: $dN_{\rm P}/(dN_{\rm C}d\Omega)(E^{\rm Prod}_{\rm kin} > 83 {\rm ~MeV}, \theta=90\degree)= (2.69\pm 0.08_{\rm stat} \pm 0.12_{\rm sys})\times 10^{-4} sr^{-1}$.Comment: 13 pages, 9 figure

PEGASO: Polar Explorer for Geomagnetic And other Scientific Observation

PEGASO (Polar Explorer for Geomagnetic And other Scientific Observation) program has been created to conduct small experiments in as many disciplines on-board of small stratospheric balloons. PEGASO uses the very low expensive pathfinder balloons. Stratospheric pathfinders are small balloons commonly used to explore the atmospheric circumpolar upper winds and to predict the trajectory for big LDBs (Long Duration Balloons). Installing scientific instruments on pathfinder and using solar energy to power supply the system, we have the opportunity to explorer the Polar Regions, during the polar summer, following circular trajectory. These stratospheric small payload have flown for 14 up to 40 days, measuring the magnetic field of polar region, by means of 3-axis-fluxgate magnetometer. PEGASO payload uses IRIDIUM satellite telemetry (TM). A ground station communicates with one or more payloads to download scientific and house-keeping data and to send commands for ballast releasing, for system resetting and for operating on the separator system at the flight end. The PEGASO missions have been performed from the Svalbard islands with the logistic collaboration of the Andoya Rocket Range and from the Antarctic Italian base. Continuous trajectory predictions, elaborated by Institute of Information Science and Technology (ISTI-CNR), were necessary for the flight safety requirements in the north hemisphere. This light payloads (<10 Kg) are realized by the cooperation between the INGV and the Physics department “La Sapienza” University and it has operated five times in polar areas with the sponsorship of Italian Antarctic Program (PNRA), Italian Space Agency (ASI). This paper summarizes important results about stratospheric missions.PNRA, ASI.Published940-9455IT. Osservazioni satellitariN/A or not JCRope

Pegaso: an ultra-light long duration stratospheric payload for polar regions flights

Stratospheric balloons are powerful and affordable tools for a wide spectrum of scientific investigations that are carried out at the stratosphere level. They are less expensive compared to satellite projects and have the capability to lift payloads from a few kilograms to a couple of tons or more, well above the troposphere, for more than a month. Another interesting feature of these balloons, which is not viable in satellites, is the short turnaround time, which enables frequent flights. We introduce the PEGASO (Polar Explorer for Geomagnetism And other Scientific Observations) project, a stratospheric payload designed and developed by the INGV (Istituto Nazionale di Geofisica e Vulcanologia), Rome and La Sapienza University, Rome. The project was sponsored by the PNRA (Progetto Nazionale di Ricerche in Antartide), Italy (Peterzen et al., 2003). This light payload (10 kg) was used by the Italian Space Agency (ASI) and Andoya Rocket Range (ARR) for five different scientific missions. PEGASO carries a 3-component flux-gate magnetometer, uses a solar cell array as the power source and has a GPS location system. The bi-directional telemetry system for data transfer and the remote control system were IRIDIUM basedINGV, PNRA, ASI, ARR, CNR, La SapienzaPublishedBeijing, China1.10. TTC - Telerilevamentoope

A comparison of the development of audiovisual integration in children with autism spectrum disorders and typically developing children

This study aimed to investigate the development of audiovisual integration in children with Autism Spectrum Disorder (ASD). Audiovisual integration was measured using the McGurk effect in children with ASD aged 7–16 years and typically developing children (control group) matched approximately for age, sex, nonverbal ability and verbal ability. Results showed that the children with ASD were delayed in visual accuracy and audiovisual integration compared to the control group. However, in the audiovisual integration measure, children with ASD appeared to ‘catch-up’ with their typically developing peers at the older age ranges. The suggestion that children with ASD show a deficit in audiovisual integration which diminishes with age has clinical implications for those assessing and treating these children

Study of the time and space distribution of beta+ emitters from 80 MeV/u carbon ion beam irradiation on PMMA

Proton and carbon ion therapy is an emerging technique used for the treatment of solid cancers. The monitoring of the dose delivered during such treatments and the on-line knowledge of the Bragg peak position is still a matter of research. A possible technique exploits the collinear 511\ \kilo\electronvolt photons produced by positrons annihilation from $\beta^+$ emitters created by the beam. This paper reports rate measurements of the 511\ \kilo\electronvolt photons emitted after the interactions of a 80\ \mega\electronvolt / u fully stripped carbon ion beam at the Laboratori Nazionali del Sud (LNS) of INFN, with a Poly-methyl methacrylate target. The time evolution of the $\beta^+$ rate was parametrized and the dominance of $^{11}C$ emitters over the other species ($^{13}N$, $^{15}O$, $^{14}O$) was observed, measuring the fraction of carbon ions activating $\beta^+$ emitters $A_0=(10.3\pm0.7)\cdot10^{-3}$. The average depth in the PMMA of the positron annihilation from $\beta^+$ emitters was also measured, D_{\beta^+}=5.3\pm1.1\ \milli\meter, to be compared to the expected Bragg peak depth D_{Bragg}=11.0\pm 0.5\ \milli\meter obtained from simulations

PEGASO: LONG DURATION BALLOONS FROM NORTH POLE

In a joint effort, the Italian Space Agency (ASI) and Andoya Rocket Range (ARR) have initiated the development of a European balloon center in Svalbard, Norway that is an ideal location for performing Long Duration Balloon (LDB) flights. After the identification of the launch location several light balloon flights have been performed since 2003. The 2004 campaign utilized a 10000 m³ balloon produced for the program by Aerostar of Sulfur Springs, Texas USA. This flight lasted 40 days and was an excellent test of the small PEGASO payload, developed (for use in Antarctica) by the National Institute of Geophysics and Volcanology (INGV) with the PNRA (Progetto Nazionale di Ricerche in Antartide) sponsorship. This payload uses an IRIDIUM based bi-directional telemetry system. During summer 2005 two flights have been performed using balloons of the same size. They carried an updated telemetry and a scientific payload which analyzed the magnetic field of the Earth. The Institute of Information Science and Technology (ISTI-CNR) team computed predictions of the balloons trajectories, both before and during flights, as well as statistical evaluations of the seasonal flight windows at the beginning of the ASI LDB program. The 2004 and 2005 missions have been defined to investigate the stratospheric winds structure and they tested the possibility for future heavy LDB flights. The Italian scientific community foresees this kind of missions from 2007-2008 campaigns. Next sections, starting from a general overview of the Italian LDB program, give the description of the Pegaso flights and, in particular, the adopted technical solutions for the on-board and ground-based equipments.PublishedVOLTERRA, PISA1.10. TTC - Telerilevamentoope