All-dielectric invisibility cloaks made of BaTiO3-loaded polyurethane foam

Transformation optics has led the way in the development of electromagnetic invisibility cloaks from science fiction to engineering practice. Invisibility cloaks have been demonstrated over a wide range of the electromagnetic spectrum, and with a variety of different fabrication techniques. However, all previous schemes have relied on the use of metamaterials consisting of arrays of sub-wavelength inclusions. We report on the first cloaking structure made of a high-kappa dielectric-loaded foam mixture. A polyurethane foam mixed with different ratios of barium titanate is used to produce the required range of permittivities, and the invisibility cloak is demonstrated to work for all incident angles over a wide range of microwave frequencies. This method will greatly facilitate the development and large-scale manufacture of a wide range of transformation optics-based structures

Sensitivity of ARGO-YBJ to different composition models in the energy range 10 ÷ 500 TeV

The ARGO-YBJ experiment is currently under construction at the Yangbajing Cosmic Ray Laboratory (4300 m a.s.l.).The detector consists of a central carpet, 74 × 78 m2, made of a single layer of Resistive Plate Counters (RPCs), and surrounded by a partially instrumented guard ring for a total instrumented area of about 6700 m2. The digital read-out, performed by means of pick-up electrodes 6.7 × 62 cm2 (strip), allows to measure the charged particle number of small size air showers. The technique of counting the number of fired strips on the ARGO carpet corresponds to operate in the 10÷500 TeV energy region where both direct and indirect measurements on the primary cosmic radiation have been performed. Many composition models have been proposed by different experiments. In this work we discuss the ability of the ARGO detector to discriminate among some models

Results of the ARGO-YBJ test experiment

A resistive plate counters (RPCs) carpet of ∼50 m2 has been put in operation in the Yangbajing Laboratory (Tibet, P.R. China) at 4300 m a.s.l., in order to study the RPCs performance at high altitude and the detector capability of imaging the EAS disc. This test has been performed in view of an enlarged use of RPCs for the ARGO-YBJ experiment. This experiment will be devoted to a wide range of fundamental issues in cosmic rays and astroparticle physics, including in particular γ-ray astronomy and γ-ray bursts physics at energies ⩾100 GeV. In this paper we present and discuss the procedures adopted to calibrate the detector and reconstruct the shower direction. Results concerning many shower features as the angular distribution, the density spectrum, the time profile of the shower front, are found well consistent with the expectation

Results from the Analysis of data collected with a 50m2 RPC carpet at Yangbajing

An RPC carpet covering View the MathML source (ARGO-YBJ experiment) will be installed in the YangBaJing Laboratory (Tibet, People's Republic of China) at an altitude of 4300 m a.s.l. A test-module of View the MathML source has been put in operation in this laboratory and about 106 air shower events have been collected. The RPC performance at high altitude and the carpet capability of reconstructing the shower features are presented

Performance of the RPCs for the ARGO detector operated at the YangBaJing Laboratory (4300 m a.s.l.)

Bakelite RPCs, assembled according to the ARGO design, have been operated in the high altitude Laboratory of YBJ using dedicated electronics to pick-up the streamer signal. Here we report on the results concerning absorbed current, single counting rate, efficiency and time resolution. Environmental data concerning the operating temperature inside the ARGO experimental hall are also reported