49 research outputs found
Study of the effects of Pauli blocking and Pauli non-locality on the optical potential
Elastic scattering angular distributions for systems with reduced mass
between 3 and 34 and energies varying between 25 and 120 MeV/nucleon were
analyzed. The stable He, its exotic partner He, and the weakly bound
Li nuclei were included as projectiles in the systematics. Optical
model data analyzes were performed with an adjustable factor of normalization
included in the imaginary part of the potential. These analyzes indicated a
reduction of absorption for systems with small reduced masses that was detected
due to the refractive nature of the scattering by light systems.Comment: 16 pages, 7 figure
Performance of the reconstruction algorithms of the FIRST experiment pixel sensors vertex detector
Hadrontherapy treatments use charged particles (e.g. protons and carbon ions) to treat tumors. During a therapeutic treatment with carbon ions, the beam undergoes nuclear fragmentation processes giving rise to significant yields of secondary charged particles. An accurate prediction of these production rates is necessary to estimate precisely the dose deposited into the tumours and the surrounding healthy tissues. Nowadays, a limited set of double differential carbon fragmentation cross-section is available. Experimental data are necessary to benchmark Monte Carlo simulations for their use in hadrontherapy. The purpose of the FIRST experiment is to study nuclear fragmentation processes of ions with kinetic energy in the range from 100 to 1000 MeV/u. Tracks are reconstructed using information from a pixel silicon detector based on the CMOS technology. The performances achieved using this device for hadrontherapy purpose are discussed. For each reconstruction step (clustering, tracking and vertexing), different methods are implemented. The algorithm performances and the accuracy on reconstructed observables are evaluated on the basis of simulated and experimental data
Novel dual single sided silicon strip detector chip for radiotherapy verification
A novel dual single sided silicon strip detector (SSSSD) chip was designed to meet clinical requirements in radiotherapy verification. An available design from Micron Semiconductor Ltd. (BB7, 500 µ m thick) was the base of a two-dimensional detector adapted into a special configuration with the aim of uniforming and minimizing foreing materials around the active area (64 × 64 mm2). With this purpose, two independent BB7 SSSSDs were mounted in a perpendicular configuration, separated by a 500 µ m kapton dielectric film with the same dimensions as the silicon wafers, thus minimizing air gaps in between. This new configuration, called the dual SSSSD chip design, was mounted on kapton printed circuit board (PCB). Both silicon wafers were divided into 32 strips, 2 mm width each. The aim of developing this detector was to allow 2D dose measurements, improve spatial resolution and perform radiotherapy treatment verification faster than with a previous prototype. Characteristics and performance of the novel detector are presented
Performance of upstream interaction region detectors for the FIRST experiment at GSI
The FIRST (Fragmentation of Ions Relevant for Space and Therapy) experiment at GSI has been designed to study carbon fragmentation, measuring 12C double differential cross sections (∂2σ/ ∂θ∂E) for different beam energies between 100 and 1000 MeV/u. The experimental setup integrates newly designed detectors in the, so called, Interaction Region around the graphite target. The Interaction Region upstream detectors are a 250 μm thick scintillator and a drift chamber optimized for a precise measurement of the ions interaction time and position on the target. In this article we review the design of the upstream detectors along with the preliminary results of the data taking performed on August 2011 with 400 MeV/u fully stripped carbon ion beam at GSI. Detectors performances will be reviewed and compared to those obtained during preliminary tests, performed with 500 MeV electrons (at the BTF facility in the INFN Frascati Laboratories) and 80 MeV/u protons and carbon ions (at the INFN LNS Laboratories in Catania)
Long range effects on the optical model of 6He around the Coulomb barrier
We present an optical model (OM) analysis of the elastic scattering data of
the reactions 6He+27Al and 6He+208Pb at incident energies around the Coulomb
barrier. The bare part of the optical potential is constructed microscopically
by means of a double folding procedure, using the Sao Paulo prescription
without any renormalization. This bare interaction is supplemented with a
Coulomb dipole polarization (CDP) potential, which takes into account the
effect of the dipole Coulomb interaction. For this CDP potential, we use an
analytical formula derived from the semiclassical theory of Coulomb excitation.
The rest of the optical potential is parametrized in terms of Woods-Saxon
shapes. In the 6He+208Pb case, the analysis confirms the presence of long range
components, in agreement with previous works. Four-body Continuum-Discretized
Coupled-Channels calculations have been performed in order to better understand
the features of the optical potentials found in the OM analysis. This study
searches to elucidate some aspects of the optical potential of weakly bound
systems, such as the dispersion relation and the long range (attractive and
absorptive) mechanisms.Comment: Accepted in Nucl. Phys. A; 26 pages, 8 figures, 6 tables
Long range absorption in the scattering of 6He on 208Pb and 197Au at 27 MeV
Quasi-elastic scattering of 6He at E_lab=27 MeV from 197Au has been measured
in the angular range of 6-72 degrees in the laboratory system employing LEDA
and LAMP detection systems. These data, along with previously analysed data of
6He + 208Pb at the same energy, are analyzed using Optical Model calculations.
The role of Coulomb dipole polarizability has been investigated. Large
imaginary diffuseness parameters are required to fit the data. This result is
an evidence for long range absorption mechanisms in 6He induced reactions.Comment: 10 pages, 10 figures, minor corrections. To appear in Nucl. Phys.
Magnetic Field Amplification in Galaxy Clusters and its Simulation
We review the present theoretical and numerical understanding of magnetic
field amplification in cosmic large-scale structure, on length scales of galaxy
clusters and beyond. Structure formation drives compression and turbulence,
which amplify tiny magnetic seed fields to the microGauss values that are
observed in the intracluster medium. This process is intimately connected to
the properties of turbulence and the microphysics of the intra-cluster medium.
Additional roles are played by merger induced shocks that sweep through the
intra-cluster medium and motions induced by sloshing cool cores. The accurate
simulation of magnetic field amplification in clusters still poses a serious
challenge for simulations of cosmological structure formation. We review the
current literature on cosmological simulations that include magnetic fields and
outline theoretical as well as numerical challenges.Comment: 60 pages, 19 Figure
Body appreciation around the world: Measurement invariance of the Body Appreciation Scale-2 (BAS-2) across 65 nations, 40 languages, gender identities, and age.
The Body Appreciation Scale-2 (BAS-2) is a widely used measure of a core facet of the positive body image construct. However, extant research concerning measurement invariance of the BAS-2 across a large number of nations remains limited. Here, we utilised the Body Image in Nature (BINS) dataset - with data collected between 2020 and 2022 - to assess measurement invariance of the BAS-2 across 65 nations, 40 languages, gender identities, and age groups. Multi-group confirmatory factor analysis indicated that full scalar invariance was upheld across all nations, languages, gender identities, and age groups, suggesting that the unidimensional BAS-2 model has widespread applicability. There were large differences across nations and languages in latent body appreciation, while differences across gender identities and age groups were negligible-to-small. Additionally, greater body appreciation was significantly associated with higher life satisfaction, being single (versus being married or in a committed relationship), and greater rurality (versus urbanicity). Across a subset of nations where nation-level data were available, greater body appreciation was also significantly associated with greater cultural distance from the United States and greater relative income inequality. These findings suggest that the BAS-2 likely captures a near-universal conceptualisation of the body appreciation construct, which should facilitate further cross-cultural research. [Abstract copyright: Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.