Second random-phase approximation with the Gogny force. First applications

We present the first applications of the second random-phase-approximation model with the finite-range Gogny interaction. We discuss the advantages of using such an interaction in this type of calculations where 2 particle-2 hole configurations are included. The results found in the present work confirm the well known general features of the second random-phase approximation spectra: we find a large shift, several MeV, of the response centroids to lower energies with respect to the corresponding random-phase-approximation values. As known, these results indicate that the effects of the 1 particle-1 hole/2 particle-2 hole and 2 particle-2 hole/2 particle-2 hole couplings are important. It has been found that the changes of the strength distributions with respect to the standard random-phase-approximation results are particularly large in the present case. This important effect is due to some large neutron-proton matrix elements of the interaction and indicates that these matrix elements (which do not contribute in the mean-field calculations employed in the conventional fit procedures of the force parameters) should be carefully constrained to perform calculation

Enabling Self-Powered Autonomous Wireless Sensors with New-Generation I2C-RFID Chips

A self-powered autonomous RFID device with sensing and computing capabilities is presented in this paper. Powered by an RF energy-harvesting circuit enhanced by a DC-DC voltage booster in silicon-on-insulator (SOI) technology, the device relies on a microcontroller and a new generation I2C-RFID chip to wirelessly deliver sensor data to standard RFID EPC Class-1 Generation-2 (Gen2) readers. When the RF power received from the interrogating reader is -14 dBm or higher, the device, fabricated on an FR4 substrate using low-cost discrete components, is able to produce 2.4-V DC voltage to power its circuitry. The experimental results demonstrate the effectiveness of the device to perform reliable sensor data transmissions up to 5 meters in fully-passive mode. To the best of our knowledge, this represents the longest read range ever reported for passive UHF RFID sensors compliant with the EPC Gen2 standard

04/15/1985 - Weekly Preview Review

Conventional RFID readers combine transmission (to the tag) and reception (from the tag) functions in a single physical device. In this paper we discuss the design and potential applications of a receive-only device, called "RFID listener", that decodes the signals from both the tag and the reader. This enables augmented RFID systems where one transmitter coexists with multiple listeners offering reception redundancy and diversity. We present a Software-Defined Radio (SDR) implementation of an RFID listener compliant with Gen2 standard, which can serve as a research tool for experimenting "on air" novel augmented RFID systems. Moreover, our listener can be used as a flexible and cheap protocol analyzer for conventional reader/tag systems. We present a test-bed setting where our listener and a conventional SDR reader are used in conjunction to measure separately the maximum downlink and uplink range. © 2011 IEEE

Mean-field calculations of exotic nuclei ground states

We study the predictions of three mean-field theoretical approaches in the description of the ground state properties of some spherical nuclei far from the stability line. We compare binding energies, single particle spectra, density distributions, charge and neutron radii obtained with non-relativistic Hartree-Fock calculations carried out with both zero and finite-range interactions, and with a relativistic Hartree approach which uses a finite-range interaction. The agreement between the results obtained with the three different approaches indicates that these results are more related to the basic hypotheses of the mean-field approach rather than to its implementation in actual calculations.Comment: 16 pages, 12 figures, 2 tables, accepted for publication in Physical Review

Low-lying magnetic excitations of doubly-closed-shell nuclei and nucleon-nucleon effective interactions

We have studied the low lying magnetic spectra of 12C, 16O, 40Ca, 48Ca and 208Pb nuclei within the Random Phase Approximation (RPA) theory, finding that the description of low-lying magnetic states of doubly-closed-shell nuclei imposes severe constraints on the spin and tensor terms of the nucleon-nucleon effective interaction. We have first made an investigation by using four phenomenological effective interactions and we have obtained good agreement with the experimental magnetic spectra, and, to a lesser extent, with the electron scattering responses. Then we have made self-consistent RPA calculations to test the validity of the finite-range D1 Gogny interaction. For all the nuclei under study we have found that this interaction inverts the energies of all the magnetic states forming isospin doublets.Comment: 19 pages, 13 figures, 7 tables, accepted for publication in Phys. Rev.

Electron-induced proton knockout from neutron rich nuclei

We study the evolution of the \eep cross section on nuclei with increasing asymmetry between the number of neutrons and protons. The calculations are done within the framework of the nonrelativistic and relativistic distorted-wave impulse approximation. In the nonrelativistic model phenomenological Woods-Saxon and Hartree-Fock wave functions are used for the proton bound-state wave functions, in the relativistic model the wave functions are solutions of Dirac-Hartree equations. The models are first tested against experimental data on $^{40}$Ca and $^{48}$Ca nuclei, and then they are applied to a set of spherical calcium isotopes.Comment: 5 pages, 2 figures. contribution to the XIX International School on Nuclear Physics, Neutron Physics and Applications, Varna (Bulgaria) September 19-25, 201