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Journal of astronomical telescopes, instruments, and systems 8(01), 014007-1 (2022). doi:10.1117/1.JATIS.8.1.014007, The prototype Schwarzschild-Couder Telescope (pSCT) is a candidate for a medium-sized telescope in the Cherenkov Telescope Array. The pSCT is based on a novel dual mirror optics design which reduces the plate scale and allows for the use of silicon photomultipliers as photodetectors. The prototype pSCT camera currently has only the central sector instrumented with 25 camera modules (1600 pixels), providing a 2.68$^{\circ}$ field of view (FoV). The camera electronics are based on custom TARGET (TeV array readout with GSa/s sampling and event trigger) application specific integrated circuits. Field programmable gate arrays sample incoming signals at a gigasample per second. A single backplane provides camera-wide triggers. An upgrade of the pSCT camera is in progress, which will fully populate the focal plane. This will increase the number of pixels to 11,328, the number of backplanes to 9, and the FoV to 8.04$^{\circ}$. Here we give a detailed description of the pSCT camera, including the basic concept, mechanical design, detectors, electronics, current status and first light., Published by SPIE, [Bellingham, Wash.]

Heterojunction photodetector based on reduced graphene oxide (rGO) has been realized using a spin coating technique. The electrical and optical characterization of bare GO and thermally reduced GO thin films deposited on glass substrate has been carried out. Ultraviolet–visible–infrared transmittance measurements of the GO and rGO thin films revealed broad absorption range, while the absorbance analysis evaluates rGO band gap of about 2.8 eV. The effect of GO reduction process on the photoresponse capability is reported. The current–voltage characteristics and the responsivity of rGO/n-Si based device have been investigated using laser diode wavelengths from UV up to IR spectral range. An energy band diagram of the heterojunction has been proposed to explain the current versus voltage characteristics. The device demonstrates a photoresponse at a broad spectral range with a maximum responsivity and detectivity of 0.20 A/W and 7 × 1010 cmHz/W, respectively. Notably, the obtained results indicate that the rGO based device can be useful for broadband radiation detection compatible with silicon device technology.

The Cherenkov Telescope Array (CTA) is the next-generation ground-based observatory for very-high-energy gamma rays. One candidate design for CTA's medium-sized telescopes consists of the Schwarzschild-Couder Telescope (SCT), featuring innovative dual-mirror optics. The SCT project has built and is currently operating a 9.7-m prototype SCT (pSCT) at the Fred Lawrence Whipple Observatory (FLWO); such optical design enables the use of a compact camera with state-of-the art silicon photomultiplier detectors. A partially-equipped camera has recently successfully detected the Crab Nebula with a statistical significance of 8.6 standard deviations. A funded upgrade of the pSCT focal plane sensors and electronics is currently ongoing, which will bring the total number of channels from 1600 to 11328 and the telescope field of view from about 2.7° to 8° . In this work, we will describe the technical and scientific performance of the pSCT.

For the first time in the history of ground-based $\gamma$-ray astronomy, the on-axis performance of the dual mirror, aspheric, aplanatic Schwarzschild-Couder optical system has been demonstrated in a $9.7$-m aperture imaging atmospheric Cherenkov telescope. The novel design of the prototype Schwarzschild-Couder Telescope (pSCT) is motivated by the need of the next-generation Cherenkov Telescope Array (CTA) observatory to have the ability to perform wide ($\geq 8^{\circ}$) field-of-view observations simultaneously with superior imaging of atmospheric cascades (resolution of $0.067^{\circ}$ per pixel or better). The pSCT design, if implemented in the CTA installation, has the potential to improve significantly both the $\gamma$-ray angular resolution and the off-axis sensitivity of the observatory, reaching nearly the theoretical limit of the technique and thereby making a major impact on the CTA observatory sky survey programs, follow-up observations of multi-messenger transients with poorly known initial localization, as well as on the spatially resolved spectroscopic studies of extended $\gamma$-ray sources. This contribution reports on the initial alignment procedures and point-spread-function results for the challenging segmented aspheric primary and secondary mirrors of the pSCT., Comment: 19 pages, 11 figures, proceedings for SPIE Optical Engineering + Applications, 2020, Online Only

In a previous work, we have presented an innovative theoretical model to describe the evolution of the life cycle of a new technology. We have proposed a mathematical approach based on a rate equation, similar to that used to describe quantum level transitions. The model is able to describe the hype curve evolution in many relevant conditions, which can be associated with various external parameters. In this article, we apply this model to describe the evolution of the number of publications in some different research fields that are very current and extremely advanced in terms of social impact. The applications have been chosen in the fields of biomolecular chemistry, genetics and superconducting nanoelectronics.

In this work, the authors investigated MoO3 films with thickness between 30 nm and 1 μm grown at room temperature by solid phase deposition on polycrystalline Cu substrates. Atomic force microscopy, scanning electron microscopy, and scanning tunneling microscopy revealed the presence of a homogenous MoO3 film with a “grainlike” morphology, while Raman spectroscopy showed an amorphous character of the film. Nanoindentation measurements evidenced a coating hardness and stiffness comparable with the copper substrate ones, while Auger electron spectroscopy, x-ray absorption spectroscopy, and secondary electron spectroscopy displayed a pure MoO3 stoichiometry and a work function ΦMoO3 = 6.5 eV, 1.8 eV higher than that of the Cu substrate. MoO3 films of thickness between 30 and 300 nm evidenced a metallic behavior, whereas for higher thickness, the resistance–temperature curves showed a semiconducting character.In this work, the authors investigated MoO3 films with thickness between 30 nm and 1 μm grown at room temperature by solid phase deposition on polycrystalline Cu substrates. Atomic force microscopy, scanning electron microscopy, and scanning tunneling microscopy revealed the presence of a homogenous MoO3 film with a “grainlike” morphology, while Raman spectroscopy showed an amorphous character of the film. Nanoindentation measurements evidenced a coating hardness and stiffness comparable with the copper substrate ones, while Auger electron spectroscopy, x-ray absorption spectroscopy, and secondary electron spectroscopy displayed a pure MoO3 stoichiometry and a work function ΦMoO3 = 6.5 eV, 1.8 eV higher than that of the Cu substrate. MoO3 films of thickness between 30 and 300 nm evidenced a metallic behavior, whereas for higher thickness, the resistance–temperature curves showed a semiconducting character.

The Italian Institute of Nuclear Physics (INFN) is currently involved in the R&D for the integration of Fondazione Bruno Kessler (FBK) Silicon Photomultipliers (SiPM) in the focal plane camera for the prototype of the Schwarzschild–Couder Telescope (pSCT) proposed to integrate the Cherenkov Telescope Array (CTA) observatory . High density FBK SiPMs optimized for the detection of Near Ultraviolet Cherenkov light (NUV-HD) will be used to equip the camera, coupled to the TARGET-7 readout electronics. A first production of 9 INFN modules is being tested and will be installed on the focal plane of the pSCT camera. Each module consists of 64 6 mm × 6 mm pixels, based on 40 μ m × 40 μ m microcells, arranged in 16-pixel matrices. The front-end electronics is based on the TARGET-7 ASIC, a 16-channel chip for sampling and digitization of the signal. Here we report measurements of the performances of the complete readout chain, including results regarding homogeneity in terms of gain and signal-to-noise ratio .

Silicon Photomultipliers (SiPM) are standard sensors widely employed for applications in which high sensitivities and fast responses in the detection of low fluxes of visible and UV photons are required. The Italian Institute of Nuclear Physics (INFN), in collaboration with Fondazione Bruno Kessler (FBK), is involved in a R&D project for SiPM sensors sensitive to near UV wavelengths. The performances of the latest technology of NUV-High-Density SiPM have confirmed that the quality of the current production technology opens the possibility to employ these devices for many applications. In this contribution, we review the performances of the latest technology of NUV-High-Density SiPM and the prospects for their use in one of the designs of the camera focal planes of Schwarschild-Couder Telescope prototype, including the development of packaging procedures of single sensors into high-density multi-SiPM modules and the development of a custom front-end ASIC for a high rate waveform sampling of the SiPM signals.

Electrical transport measurements and transient optical pump-probe experiments have been performed on epitaxial films of the electron doped Nd 1.83Ce0.17Cu4-δ compound for studying the non-equilibrium carrier dynamics in this material. Samples have been grown on (001)-oriented SrTiO3 substrates by dc sputtering in a mixed atmosphere of both Ar and O2. X-ray diffraction analysis and scanning electron microscope equipped with a wavelength dispersive spectroscopy detector have been used to characterize the structure and the composition of the thin films. Time-resolved femtosecond pump-and-probe spectroscopy has been also carried out on our samples in the temperature range 4.2K-300 K.

Transport properties of NbN/NiCu superconductor/ferromagnet (S/F) nanostripes fabricated in both in single-wire and series-parallel, meander-type configurations are presented down to T = 4.2 K. In particular, the enhancement of the superconducting critical current has been observed at smaller widths, apparently, due to an extra pinning mechanism, arising from clustering of ferromagnetic atoms inside the thin S layer. Moreover, we observed a number of characteristic voltage steps on the nanostripe current-voltage characteristics and their nature was investigated as a function of temperature. An explanation in terms of active phase-slip phenomena has been proposed based of the time-dependent Ginzburg-Landau theory and led to an estimation of the inelastic electron-phonon relaxation time τe-ph ~ 1 ps, in agreement with the τopt = 1.2±0.3 ps value, measured by the femtosecond transient optical reflectivity spectroscopy method on the same bilayer. Transient optical properties of our superconducting S/F nano-bilayers have been also investigated and compared to those obtained for pure NbN nanostripe reference samples. Finally, electrical photoresponse signals of S/F heterostructures exposed to ultraweak pulsed (width 400 ps, repetition rate ~100 MHz) laser radiation at 850 nm wavelength exhibited the falling time of voltage responses directly dependent on the NiCu overlayer. We have also noticed that the presence of the top F layer and the resulting proximity effect reduced frequency of dark counts in our samples.

The attention of the present paper is focused on the use of an infrared imaging device to monitor the thermal response of composite materials under cyclic bending. Three types of composites are considered including an epoxy matrix reinforced with either carbon fibres (CFRP) or glass fibres (GFRP) and a hybrid composite involving glass fibres and aluminium layers (FRML). The specimen surface, under bending, displays temperature variations pursuing the load variations with cooling down under tension and warming up under compression; such temperature variations are in agreement with the bending moment. It has been observed that the amplitude of temperature variations over the specimen surface depends on the material characteristics. In particular, the presence of a defect inside the material affects the temperature distribution with deviation from the usual bending moment trend.

We have investigated deep defects in structural Al-Ti alloy planar samples used in aeronautical application, by means of eddy current Non-Destructive Evaluation (NDE). The experimental system is a Scanning Magnetic Microscope (SMM) equipped with a high-critical temperature (HTc) dc Superconducting Quantum Interference Device (SQUID) magnetometer characterized by field sensitivity of 20 pT/(Hz)(1/2) and spatial resolution of about 50 mu m. We have detected cracks several millimeters below the surface, keeping relatively high spatial resolution. By mapping the magnetic field distribution, we can localize the sub-surface crack position. The experimental results confirm that this system could be used to detect defects with high resolution for the modeling of fatigue cracks in structures of aeronautical interest.

The Cherenkov Telescope Array (CTA), with more than 100 telescopes, will be the largest ever ground-based gamma-ray observatory and is expected to greatly improve on both gamma-ray detection sensitivity and energy coverage compared to current-generation detectors. The 9.7-m Schwarzschild-Couder telescope (SCT) is one of the two candidates for the medium size telescope (MST) design for CTA. The novel aplanatic dual-mirror SCT design offers a wide field-of-view with a compact plate scale, allowing for a large number of camera pixels that improves the angular resolution and reduce the night sky background noise per pixel compared to the traditional single-mirror Davies-Cotton (DC) design of ground-based gamma-ray telescopes. The production, installation, and the alignment of the segmented aspherical mirrors are the main challenges for the realization of the SCT optical system. In this contribution, we report on the commissioning status, the alignment procedures, and initial alignment results during the initial commissioning phase of the optical system of the prototype SCT., 8 pages, PoS proceedings 36th ICRC 2019 Madison