PbS quantum dot narrowband photoconductors employed for the realization of a compact wavelength-meter system.

Microbial colonization can lead to various biodeterioration phenomena in outdoor stone monuments. To prevent these issues and mitigate the negative effects of chemical control, recent research has focused on encapsulating biocides in nanostructures. We tested the antifouling efficiency of the new multifunctional coating through in situ experiments performed on the Aurelian Walls in Rome. We selected two different biocides (2-mercaptobenzothiazole and zosteric sodium salt) and loaded them into two different silica nanocontainers (nanocapsules and mesoporous particles), which were dispersed in TEOS coatings. These coatings were applied to four common lithotypes (marble, travertine, mortar, and brick). Subsequently, we accelerated the colonization by inoculating microorganisms onto half of the samples, subjecting all samples to aging cycles. We conducted colorimetric, infrared spectroscopy, and other microscopic analyses to assess their durability and antimicrobial action. Our 3-year survey indicates that the coatings demonstrated antifoulant efficiency across all samples, with higher effectiveness observed on brick and mortar compared to travertine and marble. Among the nanostructures, nanocapsules exhibited greater efficiency than mesoporous particles, and regarding the biocides, the commercial one outperformed the natural one. These findings highlighted the potential of such systems in preserving cultural heritage; however, further research and product development is imperative for practical implementation.

The Taishan Antineutrino Observatory (TAO) is a satellite experiment of the Jiangmen Underground Neutrino Observatory (JUNO). TAO consists of a spherical ton-level Gadolinium-doped Liquid Scintillator detector and its main purpose is the precise measurement of the reactor antineutrino spectrum by detection of light produced in v̅_e + p⟶ e ⁺ + n reaction, as a reference for JUNO. About 4,500 photoelectrons per MeV could be detected by instrumenting the sphere surface (∼10 m²) with state-of-the-art Silicon PhotoMultipliers (SiPMs), resulting in a sub-percent energy resolution. In this work we present the implemented architecture of the readout electronics based on low-noise, high-speed Front-End Boards (FEBs) connected to a 50×50 mm² SiPM Hamamatsu tile, composed by 32 SiPM elements of 12×6 mm² each, divided into two independent output channels. The overall 4,024 FEBs will be supplied through eight custom flanges that have to bring in about 1.5 kW. On the same flanges the 8,048 output signal cables are distributed and routed to the Front-End Controllers (FECs), based on Virtex Ultrascale FPGAs, able to manage up to eight 16-channel ADCs, for a total of 128 channels on a single FEC, with a maximum sampling rate of 250 MHz with 12-bit resolution. A dedicated trigger and data-acquisition system will filter and record occurring events, rejecting dark count events. We report the results of the characterization for the pre-production FEBs batch, following the main figures of merit defined for the experiment, showing single photoelectron resolution better than 13% and dynamic range up to 250 photoelectrons.

Silicon PhotoMultipliers (SiPMs) are widely employed for several applications, such as High Energy Physics experiments, as well as other research and industrial fields. SiPMs operating at low temperature, in particular, are the most interesting application for the new large particle detectors for neutrinos and dark matter experiments. In this work we present a low-noise, high-speed front-end electronics (Front-End Boards, FEBs) for large area SiPMs to be employed in the JUNO-TAO experiment for rare event searching. The FEBs are able to manage the signals coming from a 25 cm² SiPM tile, showing single photoelectron resolution better than 13% and dynamic range up to 250 photoelectrons. A careful approach to the front-end electronics design has shown to be critical in order to fully keep the exceptional performances of the SiPMs in terms of single photon detection, dynamic range, and fast timing properties. The sub-nanosecond timing properties make them suitable to work with the typical mixtures of liquid scintillators currently being used in particle and astroparticle physics experiments. The JUNO-TAO detector will achieve an energy resolution better than 2% at 1 MeV by the use of state-of-the-art SiPMs operating at -50°C. A dedicated readout system has been developed in order to collect and digitize the ∼8,000 channels needed to ensure the requested performances. A complete test report about the performance of the pre-production FEBs batch will be presented, showing the solution taken to ensure a high stability and reproducibility of the results.