Scientific Open-access Literature Archive and Repository
Not a member yet
16397 research outputs found
Sort by
Observing the corona and inner heliosphere with Parker Solar Probe
Get PDFThe recently launched Parker Solar Probe (PSP) mission is expected to provide unprecedented views of the solar corona and inner heliosphere. In addition to instruments devoted to taking measurements of the local solar wind, the spacecraft carries a visible imager: the Wide-field Imager for Solar PRobe (WISPR). WISPR will take advantage of the proximity of the spacecraft to the Sun to perform local imaging of the near-Sun environment. WISPR will observe coronal structures at high spatial and time resolutions, although the observed plane-of-sky will rapidly change because of the fast transit at the perihelia. We present a concise description of the PSP mission, with particular regard to the WISPR instrument, discussing its main scientific goals, targets of observations, and outlining the possible synergies with current and upcoming space missions
Updates on the PeNCIL project
Get PDFBy comparing measured and expected polarization in the HI Lyα 121.6 nm coronal emission line it is possible to infer the magnetic field in the solar corona. PeNCIL is the ideal device to perform such a measurement. It is a light transmitting polarimeter optimized at 121.6 nm, completely free of mechanical moving parts, thought as part of an internally occulted coronagraph to be flown aboard a future small solar mission. Its optical components are in de Senarmont configuration: a fixed MgF2 quarter wave retarder, a nano-wire grid polarizer (nano-WGP) and a MgF2 variable retarder modulated through a calibrated piezo-clamp (PCVR). The nano-WGP and the PCVR represent a first-ever achievement in the history of technology development for VUV. The nano-WGP fabrication is at the edge of the current nanotechnology since the pitch between wires shall be 40 nm. The PCVR is based on a MgF 2 parallelepipedic sample refractive index variations as produced by a piezo-electric clamp. This work addresses the status of the project with particular emphasis on the design and manufacturing of the nano-WGP and the PCVR
Solar limb brightening observed with SOHO/UVCS
Get PDFA model of the ultraviolet emission from chromospheric and transition region solar plasma is necessary for a correct interpretation of the measurements of the resonantly scattered spectral lines in solar corona and to determine the stray light correction needed to subtract non-coronal signal from coronagraphic data. That model is useful for analysis of SOHO/UltraViolet Coronagraph Spectrometer (UVCS) observations and for the incoming future missions for coronal study in UV spectral range. Escape probability techniques avoid the need for a full solution of the radiative transfer equation and reduce the question to a geometrical problem. In this paper we use UVCS observations to calculate a simple function to approximate a radial limb brightening
Introducing SWERTO: A regional space weather service
Get PDFThe Space WEeatherR TOr vergata university (SWERTO) service is an operational Space Weather service based on data from space-based and ground-based instruments, located in the Physics Department of the University of Rome Tor Vergata, Italy (UNITOV). The service is designed to promote the access to technical and scientific information by the regional industries whose technologies are sensible to Space Weather effects and allows registered users to access scientific data from instrumentation available to UNITOV researchers through national and international collaborations. To non-registered users, it provides a quick-look interface (spaceweather.roma2.infn.it) for the selection and visualization of such data and the visualization of the forecast for flare probability and Solar Energetic Particles (SEP) fluxes from prototype codes. The SWERTO database contains data on particles fluxes from the space missions ALTEA and PAMELA, and high-resolution and full disk spectro-polarimetric solar data. The solar data are related to solar Active Regions (ARs), observed at high resolution with the IBIS (Interferometric BIdimensional Spectropolarimeter) instrument, and full disk Line-of-Sight Doppler and magnetic field at different heights in the solar atmosphere, observed with the MOTH II telescope. SWERTO main goals are: i) design and realize a data-base with the particle fluxes recorded by the space missions and with the spectropolarimetric measurement of the solar photosphere; ii) allow an Open Access to the data-base and to prototype forecast to regional industries involved and exposed to Space Weather effects; iii) implement a tutorial and a FAQ section to help decision makers to realize and evaluate the risks from Space Weather events; iv) outreach and customer products
Uncovering carbon burning in stars
Get PDFCarbon burning takes place in stars at deep sub-Coulomb energies through the 12C(12C,α)20Ne and 12C(12C,p)23Na reactions. Here we report the first measurement of these reactions at the relevant energies via the Trojan Horse Method off the deuteron in 14N. In particular, the 12C+12C fusion has been measured from Ec.m.=2.7 MeV down to 0.8 MeV. This range of energies is relevant for several astrophysical scenarios, from superburst ignition to quiescent burning. The astrophysical S(E) factors reveal several resonances, which are responsible for a very large increase of the reaction rate at the relevant temperatures
NICA project: Challenges for heavy ion collider
Get PDFThe global scientific goal of the NICA/MPD (Nuclotron-based Ion Collider fAcility/Multy Purpose Detector) project realizing at JINR is to explore the phase diagram of strongly interacting matter in the region of high compression. The proposed program allows to search for possible signs of the phase transitions and critical phenomena in heavy ion (up to Au) collisions at centre-of-mass energies up to 11 GeV/u. The collider experiment provides optimum conditions for efficient measurements at energy scan. However, to reach required average luminosity of the order of 1027 cm−2 ·s−1 is a complicated accelerator task. In difference to high energy collider the luminosity is limited by Lasslet tune shift mainly, the beam-beam parameter is almost negligible. A flexible procedure of the beam storage and short bunch formation is to be applied to provide maximum peak luminosity in a wide energy range. To suppress luminosity dilution due to intra-beam scattering (IBS) an application of beam cooling methods is mandatory. A solution of these and other problems is presented on example of the NICA collider design
SiPMs for cryogenic temperature
Get PDFThe DarkSide-20k collaboration is preparing to equip 20 m2 of SiPMs working in liquid argon at 86 K for the direct search of WIMPs. The collaboration had to solve many technological aspects, such as the development of SiPM optimized for operation in liquid argon, the readout of large SiPM-based detectors, the reliable packaging of more than 200000 SiPMs using radiopure materials. The packaging solutions available for cryogenic applications and the performances of the newest cryogenic extended gain SiPMs from FBK will be discussed
Results from the CUORE experiment
Get PDFThe Cryogenic Underground Observatory for Rare Events (CUORE) is the first bolometric experiment searching for neutrinoless double beta decay that has been able to reach the 1-ton scale. In this talk we present the neutrinoless doube beta decay results of CUORE from examining a total TeO2 exposure of 86.3 kg yr, characterized by an effective energy resolution of 7.7 keV FWHM and a background in the region of interest of 0.014 counts/(keV kg yr). In this physics run, CUORE placed a lower limit on the decay half-life of 130Te > 1.3×1025 yr (90% C.L.). We then discuss the additional improvements in the detector performance achieved in 2018 and the latest update on the evaluation of the background budget
New results on Coulomb interaction effects in relativistic heavy ion collisions
Get PDFThe effects of the Coulomb interaction on charged pion production in Au+Au collisions at RHIC-BES energies are studied. From pT spectra of charged pions measured with STAR experiment, the negative-to-positive pion ratios as a
function of transverse momentum are obtained. Based of these pion ratio the finalstate Coulomb interaction can be investigated. The “Coulomb kick” (a momentum change due to Coulomb interaction) and initial pion ratio for RHIC-BES energies (7.7 GeV, 11.5 GeV, 19.6 GeV, 27 GeV and 39 GeV) and various centrality classes are obtained. The energy and centrality dependence of the Coulomb kick is presented.
These results are connected with the kinetic freeze-out dynamics
Dependence from the Isospin of the entrance channel in Projectile-like (PLF) break-up at Fermi energies
Get PDFThe reactions 124Xe + 64Zn and 64Ni at 35 A MeV beam incident energy (InKiIsSy, Inverse Kinematic Isobaric System) were studied at INFN-LNS with the 4π CHIMERA detector and compared to results of previous studied reactions 124,112Sn + 64,58Ni. The Intermediate Mass Fragments (IMF) production probability and emission mechanism in the projectile-like fragments (PLF) fission
were studied by using, as main observable, the angle between the center of mass velocity of the kinematical reconstructed PLF* respect to the relative velocity of the
PLF* break-up fragments. We show that prompt-dynamical emission is enhanced by increasing the projectile and target Isospin content in the entrance channel. It is found that the dynamical emission increases, separately, at the increasing of the projectile and target isospin respectively. Experimental results are compared within
the framework of the Constrained Molecular Dynamic code