Low-energy universality in three-body models

We study the low-energy universality observed in three-body models through a scale-independent approach. From the already estimated infinite number of three-body excited energy states, which happen in the limit when the energy of the subsystem goes to zero, we are able to identify the lower energies of the helium trimers as possible examples of Thomas-Efimov states. By considering this example, we illustrate the usefulness of a scaling function, which we have defined. The approach is applied to bosonic systems of three identical particles, and also to the case where two kinds of particles are present.

Exploring neutrino mixing with low energy superbeams

We explore the features of neutrino oscillation which are relevant for measurements of the leptonic CP violating phase δ and the sign of Delta;m13 2 in experiments with low-energy conventional superbeams. Toward the goal, we introduce a new powerful tool called the CP trajectory diagram in bi-probability space which allows us to represent pictorially the three effects, the effects of (a) genuine CP violation due to the sin δ term, (6) CP conserving cos δ term, and (c) fake CP violation due to earth matter, separately in a single diagram. By using the diagram, we observe that there is a two-fold ambiguity in the determination of S which is related with the sign of Delta;m13 2. Possible ways of resolving the ambiguity are discussed. In particular, we point out that an in situ simultaneous measurement of δ and the sign of Delta;m13 2 can be carried out at distances of about 700 km, or at the Phase II of the JHF experiment provided that sin δ ·Delta;m13 2 < 0, both with a megaton class water Cherenkov detector.

Halo nuclei in a three-body model and universal characteristics of low-energy few-body systems

Within general characteristics of low-energy few-body systems, we revise some well-known correlations found in nuclear physics, and the properties of low-mass halo nuclei in a three-body neutron-neutron-core model. In this context, near the critical conditions for the occurrence of an Efimov state, we report some results obtained for the neutron- 19C elastic scattering. © 2010 American Institute of Physics.

Chaotic Dynamics in a Low-Energy Transfer Strategy to the Equilateral Equilibrium Points in the Earth-Moon System

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Theoretical prevision for the low-energy 3S1-3D1 mixing parameters

Using a recent shape-independent approximation for the 3S1-3D1 mixing parameter, theoretical prevision for the low-energy mixing parameters is made. The present prevision is consistent with the deuteron binding energy, its asymptotic D-state to S-state ratio, ηd, the triplet-scattering length, and the meson exchange tail of the tensor nucleon-nucleon potential. The theoretical prevision up to an incident laboratory energy of 25 MeV is consistent with the recent multi-energy determination of mixing parameters, but is much higher than many single-energy determinations of the same. The low single-energy values of the mixing parameter could be reproduced by meson-theoretical potentials only with a substantially reduced ηd. © 1994 The American Physical Society.

Characterization of an extrapolation chamber for low-energy X-rays: Experimental and Monte Carlo preliminary results

The extrapolation chamber is a parallel-plate ionization chamber that allows variation of its air-cavity volume. In this work, an experimental study and MCNP-4C Monte Carlo code simulations of an ionization chamber designed and constructed at the Calibration Laboratory at IFEN to be used as a secondary dosimetry standard for low-energy X-rays are reported. The results obtained were within the international recommendations, and the simulations showed that the components of the extrapolation chamber may influence its response up to 11.0%. (C) 2011 Elsevier Ltd. All rights reserved.

A rationale for long-lived quarks and leptons at the LHC: low energy flavour theory

In the framework of gauged flavour symmetries, new fermions in parity symmetric representations of the standard model are generically needed for the compensation of mixed anomalies. The key point is that their masses are also protected by flavour symmetries and some of them are expected to lie way below the flavour symmetry breaking scale(s), which has to occur many orders of magnitude above the electroweak scale to be compatible with the available data from flavour changing neutral currents and CP violation experiments. We argue that, actually, some of these fermions would plausibly get masses within the LHC range. If they are taken to be heavy quarks and leptons, in (bi)-fundamental representations of the standard model symmetries, their mixings with the light ones are strongly constrained to be very small by electroweak precision data. The alternative chosen here is to exactly forbid such mixings by breaking of flavour symmetries into an exact discrete symmetry, the so-called proton-hexality, primarily suggested to avoid proton decay. As a consequence of the large value needed for the flavour breaking scale, those heavy particles are long-lived and rather appropriate for the current and future searches at the LHC for quasi-stable hadrons and leptons. In fact, the LHC experiments have already started to look for them.

Dissociative electron attachment to chloromethane.

A low energy electron may attach to a molecule, forming a metastable resonance, which may dissociate into a stable anion and a neutral radical. Chloromethane has been a good target for dissociative electron attachment studies, since it is a small molecule with a clear dissociative ‘sigma*’ shape resonance. We present potential energy curves for CH3Cl and its anion, as a function of the C-Cl distance. Due to the resonant nature of the anion, a correct description requires a treatment based on scattering calculations. In order to compute elastic cross sections and phase shifts we employed the Schwinger multichannel method, implemented with pseudopotentials of Bachelet, Hamann and Schlüter, at the static-exchange plus polarization approximation. At the equilibrium geometry, the resonance was found arround 3.3 eV, in accordance to experience. The incoming electron is captured by a ‘sigma*’ orbital located at the C-Cl bond, which will relax in the presence of this extra electron. We took this bond as the reaction coordinate, and performed several scattering calculations for a series of nuclear conformations. The phase shift obtained in each calculation was fitted by a two component function, consisting in the usual Breit-Wigner profile, which captures the resonant character, and a second order polynomial in the wave number, which accounts for the background contribution. That way, we obtained position and width of the resonance, which allowed us to build the potential energy curve. For larger distances, the anion becomes stable and usual electronic structure calculations suffice. Furthermore, the existence of a dipole-bound anion state is revealed when we employed a set of very diffuse functions. The knowledge on the behaviour of the neutral and anionic electronic states helps us in elucidating how the dissociation takes place.

Design and Setup of a New HPGe Detector Based Body Counter Capable of Detecting Also Low Energy Photon Emitters

The present work describes the development of a new body-counter system based on HPGe detectors and installed at IVM of KIT. The goal, achieved, was the improvement of the ability to detect internal contaminations in the human body, especially the ones concerning low-energy emitters and multiple nuclides. The development of the system started with the characterisation of detectors purchased for this specific task, with the optimisation of the different desired measurement configurations following and ending with the installation and check of the results. A new software has been developed to handle the new detectors.

Prototipo di schermo adattativo basato su Android e Bluetooth Low Energy

La tesi nasce da un'attività di ricerca approfondita su alcune tecnologie innovative e all'avanguardia nell'ambito del mobile computing e dell'Internet of Things. Tra queste il focus principale è orientato allo studio del Bluetooth Low Energy, nuova specifica di Bluetooth caratterizzata principalmente da un consumo di energia assai ridotto. In particolare, si è approfondito il suo funzionamento nel caso dei beacon, piccoli dispositivi che permettono una localizzazione mediante l'invio di un segnale BLE. Inoltre è stata analizzata la possibilità di interazione con Android, poiché oggigiorno non si può evitare di pensare a come queste tecnologie possano interfacciarsi con il mondo degli smartphone e dei tablet. Come conseguenza di tale attività di ricerca è stato analizzato un caso di studio che permettesse di applicare le tecnologie studiate e la loro interazione. Si è pensato quindi a un piccolo sistema distribuito per schermi adattativi (capaci di modificare i contenuti visualizzati in relazione ad eventi esterni) affinché ogni schermo mostrasse dinamicamente l'orario delle lezioni di ciascuno studente all'avvicinarsi di quest'ultimo, e solo per il tempo di permanenza nei pressi dello schermo. Si è quindi progettato e sviluppato un prototipo, e infine durante il testing si sono potute verificare le attuali potenzialità di queste tecnologie e trarre conclusioni sulla possibilità della loro futura diffusione e di impiego in contesti differenti.

Realizzazione di un'interfaccia universale in tecnologia Bluetooth Low Energy per sensori integrati

Lo scopo dell’elaborato di tesi è la progettazione e lo sviluppo di un’applicazione per il modulo Bluetooth Low Energy (BLE) Texas Instrument CC2650 in grado di leggere le informazioni da un sensore analogico, tramite un Analog-Digital- Converter (ADC), e di scambiare i dati con uno smartphone Android in tempo reale. L’interfaccia realizzata deve essere universale, ovvero dovrà essere compatibile con sensori di diverso tipo, facilmente estensibile per l’aggiunta di un numero maggiore di periferiche di lettura e utilizzabile con un ampio numero di dispositivi.

Attenuazione del multipath attraverso tecniche di diversità per applicazioni beacon tramite segnali Bluetooth Low Energy

In questo elaborato è stato effettuato uno studio di soluzioni tecnologiche per eseguire una localizzazione di prossimità in ambienti indoor tramite la percezione di segnali Bluetooth Low Energy. Il sistema analizzato e sperimentato è composto da un dispositivo in ricezione che effettua una stima della distanza che intercorre con il trasmettitore, tramite la valutazione della potenza del segnale ricevuto. A causa della propagazione indoor, tale stima risulta poco accurata in termini di ranging in quanto vengono a generarsi delle fluttuazioni istantanee del segnale ricevuto dovute a fenomeni di multipath. L’obiettivo di questo progetto è stato quello di mitigare queste oscillazioni sfruttando due trasmettitori al posto di uno, effettuando quindi in ricezione opportune combinazioni fra i segnali ricevuti (Diversity Combining Techniques).

Confronto tra Bluetooth classic e Bluetooth low energy nelle comunicazioni tra sensori inerziali e dispositivi mobili in applicazioni biomeccaniche in ambito medico e sportivo

In questo elaborato sono stati confrontati i moduli bluetooth WT11, BLE113 , BT121 rispetto alle loro caratteristiche di banda, consumo, range e utilizzabilita in un contesto applicativo stringente come quello degli utilizzi biomeccanici. Si sono prima elencati i settori di riferimento, per poi descrivere il contesto applicativo in ambito medico e sportivo. Il confronto finale ha tenuto conto delle modalita di comunicazione bluetooth classic e bluetooth low energy, cercando di motivare quale modulo risulti migliore per questo particolare e innovativo contesto.