Abstract
Time-dependent energy spectra of galactic cosmic rays (GCRs) carry crucial information regarding their origin and propagation throughout the interstellar environment. When observed at the ...Earth, after traversing the interplanetary medium, such spectra are heavily affected by the solar wind and the embedded solar magnetic field permeating the inner sectors of the heliosphere. The activity of the Sun changes significantly over an 11 yr solar cycle—and so does the effect on cosmic particles; this translates into a phenomenon called solar modulation. Moreover, GCR spectra during different epochs of solar activity provide invaluable information for a complete understanding of the plethora of mechanisms taking place in various layers of the Sun’s atmosphere and how they evolve over time. The High-Energy Particle Detector (HEPD-01) has been continuously collecting data since 2018 August, during the quiet phase between solar cycles 24 and 25; the activity of the Sun is slowly but steadily rising and is expected to peak around 2025/2026. In this paper, we present the first spectra for ∼50–250 MeV galactic protons measured by the HEPD-01 instrument—placed on board the CSES-01 satellite—from 2018 August to 2022 March over a one-Carrington-rotation time basis. Such data are compared to the ones from other spaceborne experiments, present (e.g., EPHIN, Parker Solar Probe) and past (PAMELA), and to a state-of-the-art three-dimensional model describing the GCRs propagation through the heliosphere.
We report on microwave emission from linear parallel arrays of underdamped Josephson junctions, which are described by the Frenkel-Kontorova (FK) model. Electromagnetic radiation is detected from the ...arrays when biased on current singularities (steps) appearing at voltages V(n)=Φ(0)(nc̅/L), where Φ(0)=2.07×10(-15) Wb is the magnetic flux quantum, and c̅, L, and n are, respectively, the speed of light in the transmission line embedding the array, L its physical length, and n an integer. The radiation, detected at fundamental frequency c̅/2L when biased on different singularities, indicates shuttling of bunched 2π kinks (magnetic flux quanta). Resonance of flux-quanta motion with the small-amplitude oscillations induced in the arrays gives rise to fine structures in the radiation spectrum, which are interpreted on the basis of the FK model describing the resonance. The impact of our results on design and performances of new digital circuit families is discussed.
Abstract The Electric Field Detector (EFD-02) on board the second China Seismo-Electromagnetic Satellite (CSES-02) will measure the electric field components at a Low Earth Orbit (LEO) over a wide ...frequency band (DC – 3.5 MHz) and with 1 μV/m sensitivity in the Low Frequency band. EFD-02 will measure the voltage differences between pairs of probes installed at the tips of four booms deployed from the satellite. In this article, we describe the Zynq System on Chip (SoC)-based digital hardware subsystem dedicated to signal processing, and the selected implementation strategy, which successfully complied to the specific requirements of the space mission. Furthermore, we present a comprehensive overview of the assessed instrument performance.
We investigate the magnetic response of transmission lines with embedded Josephson junctions and thus generating a 1D underdamped array. The measured multi-junction interference patterns are compared ...with the theoretical predictions for Josephson supercurrent modulations when an external magnetic field couples both to the inter-junction loops and to the junctions themselves. The results provide a striking example of the analogy between Josephson phase modulation and 1D optical diffraction grid. The Fiske resonances in the current-voltage characteristics with voltage spacing , where L is the total physical length of the array, the magnetic flux quantum and the speed of light in the transmission line, demonstrate that the discrete line supports stable dynamic patterns generated by the ac Josephson effect interacting with the cavity modes of the line.
We have designed and realized a Front-End chip for MPPC in standard CMOS 0.35μm technology. The channel presents a low input impedance in order to reduce as much as possible the recovery time of the ...sensor. This is achieved using the current domain for processing signals through the current conveyors (CCII) as building blocks of the channel. A current feed-back with low-pass filter has also been used to realize a sensitive improvement of the correction of the pile-up problem, in case of high repetition rate events. An independent arming threshold is available for each channel, providing the selection of the event through the peak level (proportional to the number of simultaneously hit pixels) reached by the signal. A constant-fraction functionality is present in order to reduce the well know time-walk problem. The delay in the correspondent branch is obtained by using an additional CCII block. The digital output of the discriminator channel has adjustable time width. The pilot chip is made up of five channels. All the values of the independent thresholds are stored in 10−bit registers as well as the values of the trigger output width and the main polarization current of the CCII blocks. All the registers are writable from a standard three-wire SPI. These features make the chip fully self-consistent. In this work we present and discuss the simulation results together with the preliminary test performed.
In recent works we presented the results of the characterization and the study of performance of several Silicon Photomultipliers delivered from MEPHI (Moscow Engineering and Physics Institute) and ...we proposed an electrical model of the SiPM to be used in analog simulations for the VLSI design of the pilot chip with
0.35
μ
m
technology produced. The results of the simulations was also presented. In this work we present the results of several test performed on the SiPM connected to the pilot chip. We also describe the prototype board with a micro-controller designed to adjust the parameters of the chip and to provide an adjustable and temperature controlled power supply to the SiPM. The results of the tests obtained allow us to refine the circuits design for the next chip. This chip has been developed inside the ALTCRISS and KLOE collaboration.
The goal of the NA62 experiment at the CERN SPS is the measurement of the Branching Ratio of the very rare kaon decay K super(+) arrow right pi super(+) nu nu with a 10% accuracy by collecting 100 ...events in two years of data taking. An efficient photon veto system is needed to reject the K super(+) arrow right pi super(+) pi super(0) background and a liquid krypton electromagnetic calorimeter will be used for this purpose in the 1-10 mrad angular region. The L0 trigger system for the calorimeter consists of a peak reconstruction algorithm implemented on FPGA by using a mixed parallel architecture based on soft core Altera NIOS II embedded processors together with custom VHDL modules. This solution allows an efficient and flexible reconstruction of the energy-deposition peak. The system will be totally composed of 36 TEL62 boards, 108 mezzanine cards and 215 high-performance FPGAs. We describe the design, current status and the results of the first performance tests.
We present a new limit on the production of a light dark-force mediator with the KLOE detector at DAΦNE. This boson, called U, has been searched for in the decay ϕ→ηU, U→e+e−, analyzing the decay ...η→π0π0π0 in a data sample of 1.7 fb−1. No structures are observed in the e+e− invariant mass distribution over the background. This search is combined with a previous result obtained from the decay η→π+π−π0, increasing the sensitivity. We set an upper limit at 90% C.L. on the ratio between the U boson coupling constant and the fine structure constant of α′/α<1.7×10−5 for 30<MU<400 MeV and α′/α⩽8×10−6 for the sub-region 50<MU<210 MeV. This result assumes the Vector Meson Dominance expectations for the ϕηγ⁎ transition form factor. The dependence of this limit on the transition form factor has also been studied.
Optical wavelength multiplexing is a widely used technique in Information and Communication Technology to increase maximum data transmission bandwidth on a single optical fiber. We propose wavelength ...multiplexing/demultiplexing using optical Ring Resonators (RR) on a silicon photonics circuit for fast timing highly segmented detectors readout. A cascaded microrings, sharing a common bus waveguide with individual drop waveguides, can be used to encode the readout of an array of detectors on a single optical fiber. The device works using a silicon strip-waveguide coupled to a set of N high Q-factor RR filters driven by a different ASIC (Application-Specific Integrated Circuit) front-end electronics.
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