Nuovo Cimento Della Societa Italiana Di Fisica C-colloquia on Physics 

About: Nuovo Cimento Della Societa Italiana Di Fisica C-colloquia on Physics is an academic journal. The journal publishes majorly in the area(s): Large Hadron Collider & Cosmic ray. Over the lifetime, 78 publications have been published receiving 488 citations.

Insolation signatures of Quaternary climatic changes

Abstract: From a set of simple trigonometrical formulae allowing the computation of long-term variations of the Earth's orbital elements, mid month daily insolations have been computed for each 10-deg latitude and, by steps of 1000 y, for one million years before present (YBP) and one hundred thousand years after present. The deviations from present values and especially from mean values computed over the past 10/sup 6/ y are graphically reproduced for 60 degrees N latitude which is thought to be one of the most sensitive latitudes as far as glacial-intergalactic sequences of the Quaternary period are concerned. From these data, some specific features, called insolation signatures, of the insolation pattern are found to be significantly related to well-established climatic changes, like the 125000 YBP interglacial, the 70000 YBP persistent-cooling tend and the 20000 YBP glacial maximum. Mathematical techniques of data analysis, like harmonic analysis and principal-component analysis, have been used to statistically improve the validity of the relationship that has been found between glaciation extent, mainly their triggering, and April to October insolations.

3He/4He ratios of fumaroles and bubbling gases of hot springs in Tatun Volcano Group, North Taiwan

Abstract: Eleven representative fumarolic gases and bubbling gases of hot springs have been collected from Tatun Volcano Group, North Taiwan for the helium isotope measurement. All the samples, except one, exhibit consistent corrected helium isotope ratios (3He/4He) with the mean value of 4.67 times of air ratios (RA). The preliminary helium data show that more than 60% of helium composition comes from deep magmatic source in this area. It implies that a relic magma reservoir may still exist underneath North Taiwan.

Multibaseline phase unwrapping for INSAR topography estimation

Abstract: Multibaseline Synthetic Aperture Radar (SAR) Interferometry (INSAR) can be successfully exploited for automatic phase unwrapping and high quality Digital Elevation Model (DEM) reconstruction. The information coming from several interferograms with different baselines increases the elevation ambiguity interval and allows automatic phase unwrapping. The height of each pixel in the image is considered as a random variable: a Maximum-Likelihood (ML) estimation of the height is carried out by exploiting the probability density function of the interferometric phase, that depends on the local coherence value. After phase unwrapping is possible to combine all the information available, getting a combined DEM that is more reliable than each single DEM. Results obtained using ERS-1/2 SAR data gathered over Vesuvius and Etna are presented. In both cases an accuracy better than 8 meters was obtained.

Novel Geometrical Concept of a High Performance Brain PET Scanner : Principle, Design and Performance Estimates

Abstract: We present the principle, a possible implementation and performance estimates of a novel geometrical concept for a high resolution positron emission tomograph. The concept, which can for example be implemented in a brain PET device, promisses to lead to an essentially parallax free 3D image reconstruction with excellent spatial resolution and constrast, uniform over the complete field of view. The key components are matrices of long axially oriented scintillator crystals which are read out at both extremities by segmented Hybrid Photon Detectors. We discuss the relevant design considerations for a 3D axial PET camera module, motivate parameter and material choices, and estimate its performance in terms of spatial and energy resolution. We support these estimates by Monte Carlo simulations and in some cases by first experimental results. From the performance of a camera module, we extrapolate to the reconstruction resolution of a 3D axial PET scanner in a semi-analytical way and compare it to an existing state-of-the art brain PET device. We finally describe a dedicated data acquisition system, capable to fully exploit the advantages of the proposed concept. We conclude that the proposed 3D Axial concept and the discussed implementation is a competitive approach for high resolution brain PET. Excellent energy resolution and Compton enhanced sensitivity are expected to lead to high quality reconstruction and reduced scanning times.

String Theory and Pre-big bang Cosmology

Abstract: Summary. In string theory, the traditional picture of a Universe that emerges from the inflation of a very small and highly curved space-time patch is a possibility, not a necessity: quite different initial conditions are possible, and not necessarily unlikely. In particular, the duality symmetries of string theory suggest scenarios in which the Universe starts inflating from an initial state characterized by very small curvature and interactions. Such a state, being gravitationally unstable, will evolve towards higher curvature and coupling, until string-size effects and loop corrections make the Universe “bounce” into a standard, decreasing-curvature regime. In such a context, the hot big bang of conventional cosmology is replaced by a “hot big bounce” in which the bouncing and heating mechanisms originate from the quantum production of particles in the high-curvature, large-coupling pre-bounce phase. Thanks to the strong coupling there is also an associate production of higher-dimensional branes, which could prepare (and provide the initial conditions for) a subsequent phase of brane-dominated inflation.