plasma and fields evaluation at the chinese seismo electromagnetic satellite for electric field detector measurements

Model predictions are presented to evaluate the electrodynamic parameters as expected at the orbit of the China Seismic-Electromagnetic Satellite (CSES). The main objective of this paper is that of improving the accuracy of the electric field detectors (EFDs), which are installed on CSES and will measure the field vector in a wideband from dc up to 3.5 MHz. The electric field components are derived from the probe floating potential readings, thus an accurate characterization of the space environment is needed to model the currents collected from the ionosphere and establish the EFD probe response. The plasma environment and the magnetic field along the orbit are determined using the standard IRI and IGRF models. Simulations are used to determine the bias currents, which have to be applied to the probes to minimize the contact impedance between the EFDs and the ionospheric plasma. Correction voltages required to remove the $\vec {v}\times \vec {B}$ electric field from the EFD measurements are also estimated

Numerical Evidence of a Critical Line in the 4d Ising Spin Glass

We study numerically the four-dimensional ± J Ising spin-glass at nonzero external magnetic field. We find numerical evidence of the existence of the Almeida-Thouless critical line. The critical exponents differ from those found at zero external magnetic field

Silicon photomultipliers: On ground characterizations and modelling for use in front-end electronics aimed to space-borne experiments

Abstract Silicon Photomultipliers (Si-PM) consist of an array of semiconductor photodiodes joint on the common substrate and operating in limited geiger mode. A new generation of Si-PM is currently under test in INFN Rome Tor Vergata facilities: they consist of a 5625 element, 3 * 3 mm 2 array with an improved light response. These elements have been characterized. Furthermore, a functional model of the Si-PM has been developed to be used in a VLSI development of front-end electronics

The confining-Higgs phase transition in U(1)-Higgs LGT

Abstract We simulate the compact U(1)-Higgs model in a four-dimensional lattice. We present a numerical study for the behaviour around the region where the transition between the confining and Higgs phases disappears. The transition line is found to be first order and to end in a second-order point. We measure the critical exponents of the endpoint obtaining the mean field ones within errors

Gamma-Ray Burst observations by the high-energy charged particle detector on board the CSES-01 satellite between 2019 and 2021

In this paper we report the detection of five strong Gamma-Ray Bursts (GRBs) by the High-Energy Particle Detector (HEPD-01) mounted on board the China Seismo-Electromagnetic Satellite (CSES-01), operational since 2018 on a Sun-synchronous polar orbit at a $\sim$ 507 km altitude and 97$^\circ$ inclination. HEPD-01 was designed to detect high-energy electrons in the energy range 3 - 100 MeV, protons in the range 30 - 300 MeV, and light nuclei in the range 30 - 300 MeV/n. Nonetheless, Monte Carlo simulations have shown HEPD-01 is sensitive to gamma-ray photons in the energy range 300 keV - 50 MeV, even if with a moderate effective area above $\sim$ 5 MeV. A dedicated time correlation analysis between GRBs reported in literature and signals from a set of HEPD-01 trigger configuration masks has confirmed the anticipated detector sensitivity to high-energy photons. A comparison between the simultaneous time profiles of HEPD-01 electron fluxes and photons from GRB190114C, GRB190305A, GRB190928A, GRB200826B and GRB211211A has shown a remarkable similarity, in spite of the different energy ranges. The high-energy response, with peak sensitivity at about 2 MeV, and moderate effective area of the detector in the actual flight configuration explain why these five GRBs, characterised by a fluence above $\sim$ 3 $\times$ 10$^{-5}$ erg cm$^{-2}$ in the energy interval 300 keV - 50 MeV, have been detected.Comment: Accepted for publication in The Astrophysical Journal (ApJ

Electric field computation analysis for the Electric Field Detector (EFD) on board the China Seismic-Electromagnetic Satellite (CSES)

The floating potential variability of the Electric Field Detector (EFD) probes, on board the Chinese Seismo-Electromagnetic Satellite (CSES), has been modeled, and the effects of several structural and environmental elements have been determined. The expected floating potentials of the probes are computed considering the ambient ionospheric plasma parameter variations. In addition, the ion collection variability, due to the different probe attitudes along the orbit, and its effect on each floating potential, are considered. Particular attention is given to the analysis of the shadow produced by the stubs, in order to determine the artificial electric field introduced by instrumental effects which has to be subtracted from the real measurements. The modulation of the altered electric field, due to the effect on shadowing of the ion drift, as measured by the ESA satellite Swarm A in a similar orbit, is also modeled. Such simulations are made in preparation of real EFD data analysis performed during the upcoming flight of CSES.Published2206-22162A. Fisica dell'alta atmosferaJCR Journa

A Neuromorphic aVLSI network chip with configurable plastic synapses

We describe and demonstrate the key features of a neuromorphic, analog VLSI chip (termed F-LANN) hosting 128 integrate-and-fire (IF) neurons with spike-frequency adaptation, and 16 384 plastic bistable synapses implementing a self-regulated form of Hebbian, spike-driven, stochastic plasticity. We were successfully able to test and verify the basic operation of the chip as well as its main new feature, namely the synaptic configurability. This configurability enables us to configure each individual synapse as either excitatory or inhibitory and to receive either recurrent input from an on-chip neuron or AER (address event representation)-based input from an off-chip neuron. It's also possible to set the initial state of each synapse as potentiated or depressed, and the state of each synapse can be read and stored on a computer. The main aim of this chip is to be able to efficiently perform associative learning experiments on a large number of synapses. In the future we would like to connect up multiple F-LANN chips together to be able to perform associative learning of natural stimulus sets