Abstract
All known small solar system bodies have diameters between a few meters and a few thousands of kilometers. Based on the collisional evolution of solar system bodies, a larger number of ...asteroids with diameters down to ∼2 m is thought to exist. As all solar system bodies, small bodies can be passive sources of high-energy gamma-rays, produced by the interaction of energetic cosmic rays impinging on their surfaces. Since the majority of known asteroids are in orbits between Mars and Jupiter (in a region known as the Main Belt), we expect them to produce a diffuse emission close to the ecliptic plane. In this work, we have studied the gamma-ray emission coming from the ecliptic using the data collected by the Large Area Telescope (LAT) onboard the Fermi satellite. We have fit the results with simulations of the gamma-ray intensity at the source level (calculated with the software
FLUKA
) to constrain the small solar system bodies population. Finally, we have proposed a model describing the distribution of asteroid sizes and we have used the LAT data to constrain the gamma-ray emission expected from this model and, in turn, on the model itself.
Abstract
The Cherenkov Telescope Array (CTA) will be the next major observatory for Very High Energy gamma-ray astronomy. Its optical throughput calibration relies on muon Cherenkov rings. This work ...is aimed at developing a fast and efficient muon tagger at the camera level for the CTA telescopes. A novel technique to tag muons using the capabilities of silicon photomultiplier Compact High-Energy Camera CHEC-S, one of the design options for the camera of the small size telescopes, has been developed, studying and comparing different algorithms such as circle fitting with the Taubin method, machine learning using a neural network and simple pixel counting. Their performance in terms of efficiency and computation speed was investigated using simulations with varying levels of night sky background light. The application of the best performing method to the large size telescope camera has also been studied, to improve the speed of the muon preselection.
Satellite experiments for gamma-ray and cosmic-ray detection employ plastic scintillators to discriminate charged from neutral particles in order to correctly identify gamma-rays and charged nuclei. ...The High Energy Cosmic Radiation Detection (HERD) facility will be among these experiments, to be installed onboard the future Chinese Space Station (CSS), to detect cosmic-rays and gamma-rays up to TeV energies. The plastic scintillator detector (PSD) will consist of scintillator tiles or bars coupled to Silicon Photomultipliers (SiPMs). To discriminate gamma-rays from charged particles and measure the ion charge up to iron nuclei a wide dynamic range is required, from few tens up to thousands of photoelectrons. We have equipped a plastic scintillator tile prototype with SiPMs produced by Hamamatsu and AdvanSiD and coupled their analog signals to the DT5550W board based on the CITIROC ASIC, produced by CAEN SpA. The CITIROC ASIC allows both the formation of a fast trigger with a configurable threshold and the digitization of analog waveforms after a preamplification and shaping stage along two paths with different gain settings. The performance of our prototype will be shown.
Plastic scintillators are widely used for anti-coincidence systems and for the identification of charged cosmic-ray nuclei in satellite experiments. For this reason, a plastic scintillator detector ...(PSD) should have a high detection efficiency for charged cosmic rays and a very good capability of measuring charges. We implemented a full and customizable simulation tool to investigate the performance of a PSD coupled to Silicon Photomultipliers. The overall performance of the detector is studied by tracking optical photons produced inside the scintillator. The simulation will be used for the design of a PSD for future space experiments, such as HERD, AMEGO, e-Astrogam. In this work we investigated in detail the effect of Birks’ saturation in the discrimination of charged ions up to iron nuclei. We will show the comparison between simulations and measurements conducted on prototype scintillator tiles.
The High Energy Cosmic Radiation Detection (HERD) facility, onboard the future China’s Space Station (CSS), will provide high quality data on charged cosmic rays and gamma rays in the energy range ...from few GeV to PeV. HERD will be equipped with a fine granularity cubic crystals calorimeter and a precision tracker detector. The entire instrument will be surrounded by a Plastic Scintillator Detector (PSD) that will be used to discriminate charged from neutral particles in order to correctly identify gamma-rays and nuclei. One proposed configuration for the HERD PSD consists of tiles of plastic scintillator, optically coupled to SiPMs. In 2019-2020, two beam tests were performed at CNAO (Centro Nazionale di Adroterapia Oncologica) in Pavia (Italy), exposing some PSD tiles, equipped with SiPMs, to low-beta p and C ion beams in order to evaluate the detector response to heavy ions. Spatial and temporal resolution were also evaluated using a radioactive source.
Abstract
An incremental version of the fourth catalog of active galactic nuclei (AGNs) detected by the Fermi Large Area Telescope is presented. This version (4LAC-DR3) derives from the third data ...release of the 4FGL catalog based on 12 yr of
E
> 50 MeV gamma-ray data, where the spectral parameters, spectral energy distributions (SEDs), yearly light curves, and associations have been updated for all sources. The new reported AGNs include 587 blazar candidates and four radio galaxies. We describe the properties of the new sample and outline changes affecting the previously published one. We also introduce two new parameters in this release, namely the peak energy of the SED high-energy component and the corresponding flux. These parameters allow an assessment of the Compton dominance, the ratio of the inverse-Compton to the synchrotron-peak luminosities, without relying on X-ray data.
A light tracker based on scintillating fibers with SiPM readout Mazziotta, M.N.; Altomare, C.; Bissaldi, E. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/2022, Letnik:
1039
Journal Article
Recenzirano
We have developed a novel light tracker based on plastic scintillating fiber arrays readout with Silicon Photomultipliers (SiPMs). The tracker consists of multiple planes, with the fibers in each ...plane oriented perpendicularly to those in the adjacent plane, in order to allow 3D track reconstruction. The fibers in each plane have round cross sections, with a diameter of 500μm, and are arranged in two staggered layers in a close-packed configuration. The fibers are readout by means of SiPM arrays with a 250μm strip pitch placed at one of their ends. Scintillating fibers allow a reduced material budget while providing a good spatial resolution and a fast response. This design is therefore suitable to track low-energy particles, such as the lowest energy cosmic rays or the electrons produced in Compton scatterings of gamma rays with energies down to 100 keV. We have built a detector prototype, equipped with Hamamatsu 128-channel SiPM arrays, readout with 32-channel PETIROC2A front-end ASICs. These ASICs are controlled by a custom data acquisition system board equipped with Xilinx Kintex-7 FPGA with self-triggering capabilities. The prototype has been tested with particle beams, cosmic rays and radioactive sources. The tracker design will be presented and performance of the prototype will be discussed.
A compact, light scintillating fiber tracker with SiPM readout Pillera, R.; Altomare, C.; Bissaldi, E. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
March 2023, 2023-03-00, Letnik:
1048
Journal Article
Recenzirano
We present the concept of a novel compact and light tracker based on arrays of plastic scintillating fibers readout with Silicon Photomultipliers (SiPMs). The tracker will be composed of multiple ...planes, with the fibers in each plane oriented perpendicularly to those in the adjacent planes. Each plane will consist of two staggered layers of fibers, having a round cross section with 500 μm diameter and arranged in a close packed configuration. Scintillation photons produced in the fibers will be collected by SiPM arrays with 250 μm strip pitch located at one end of the fibers. This configuration will ensure an accurate spatial resolution and a fast response, while keeping a reduced material budget. Hence, this detector will be suitable to track low energy particles and will be able to efficiently detect the Compton scattered electrons produced by gamma rays with energies down to 100 keV. We built a reduced scale tracker prototype, using Hamamatsu 128 channel SiPM arrays and 32 channel PETIROC2A front end ASICs readout. The latter are controlled by a custom data acquisition board with self triggering capabilities. We tested this prototype with cosmic rays, radioactive sources and accelerated particle beams.
After large galaxies merge, their central supermassive black holes are expected to form binary systems. Their orbital motion should generate a gravitational wave background (GWB) at nanohertz ...frequencies. Searches for this background use pulsar timing arrays, which perform long-term monitoring of millisecond pulsars at radio wavelengths. We used 12.5 years of Fermi Large Area Telescope data to form a gamma-ray pulsar timing array. Results from 35 bright gamma-ray pulsars place a 95% credible limit on the GWB characteristic strain of 1.0 × 10
at a frequency of 1 year
. The sensitivity is expected to scale with
, the observing time span, as Formula: see text. This direct measurement provides an independent probe of the GWB while offering a check on radio noise models.
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