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Optical emission spectroscopy and microwave reflectometry for magnetised plasmas: Applications to ion sources and fusion machines
Get PDFInvestigation of magnetised plasmas by advanced diagnostics is a relevant topic in the frame of ion sources for high-performance particle accelerators and in thermonuclear fusion research for energetic purposes. In this paper, we
propose two different diagnostic techniques to provide complementary information on plasma properties: high-resolution Optical Emission Spectroscopy (OES) and Microwave Reflectometry (MR). Several OES measurements have been carried out at INFN-LNS to determine cold electron plasma density and temperature in the framework of the PANDORA project. Experimental results will be here presented
together with an ongoing R&D simulation work for the MR system to be employed in the Divertor Tokamak Test (DTT) facility in view of reconstructing the 1D electron density profile accurately. An overview of the perspectives and challenges of the two diagnostic systems will be given
Design and test of C-band prototypes linac for FLASH radiotherapy
Get PDFFLASH Radiotherapy (RT) represents an innovative technique in cancer treatment, delivering high radiation doses in microsecond pulses. In collaboration with INFN, Sapienza University of Rome is actively engaged in developing
innovative C-band structures for Very High Electron Energy (VHEE) linac to achieve the FLASH regime and to treat deep tumors. The RF electromagnetic design of the accelerating structures was carried out using CST Studio Suite. Following the design phase, we proceeded with the mechanical design and fabrication of copper prototypes. To assess their performance, low-power RF tests were conducted at Sapienza University of Rome and the field measurements within the cavity were obtained using the bead-pull technique.These prototypes serve as crucial milestones towards the final structure of the VHEE Linac
Color specification: Comparison between contact and non-contact measurement methodologies
Get PDFA methodological study regarding color specification through both contact and non-contact techniques is presented. The principal aim is the evaluation of chromatic differences obtained by the two methods varying the experimental
parameters in order to quantify their influence. The results obtained for cardboard cubes of seven hues, red (R), green (G), blue (B), yellow (Y), black (K), white (W) and grey (Gy), considering CIELAB 1976 coordinates, are presented. The color differences were evaluated through the ΔE values and in the chromatic plane using Δa∗ and Δb∗ differences. The study was performed using a Konica Minolta® CM
2600d spectrophotometer and a Konica Minolta CS-1000A spectroradiometer for, respectively, contact and non-contact measurements under different experimental conditions. Different illuminants (D65, A and F11) and both the 2◦ and 10◦ CIE standard observers were selected. In both cases the circular measuring area used was 11mm in diameter. The results obtained show good agreement except for the extreme achromatic black and white cubes. The best agreement was obtained when illuminant A is used for the colorimetric calculation. The obtained results provide novel and useful insights into the behavior of the color coordinates according to the chosen experimental conditions
The influence of ametropia on pupil diameter
Get PDFThe pupil changes its size in response to a series of factors among which the most relevant one is variations in the level of environmental brightness. Some studies proposed that pupil diameter can also be affected by refractive
condition although no consensus has been reached on this topic as other intervening factors could also explain such trend.Here we used a causal approach to tackle this point. We measured pupil diameters in a group of myopes and a group of hyperopes in two separate conditions. A condition where participants did not wear any correction (NC condition) and a condition in which their ametropia was corrected by means of daily disposable contact lenses matching their individual spherical equivalent (CL condition). In both conditions, pupil diameter was assessed at three distinct light levels (photopic, mesopic and scotopic). Results revealed a significant difference in pupil diameter between hyperopes and myopes in the NC condition at all the three light levels. Nevertheless, this difference was robustly reduced in the CL condition suggesting a causal relationship between ametropia and pupil size
Dehydration and surface friction of Kalifilcon A and Senofilcon A contact lenses
Get PDFIn the context of contact lens (CL) wear, it is crucial to tailor the dehydration tendency and surface friction of CLs to ensure comfort. This becomes particularly significant when dealing with eyes with damaged or absent glycocalyx,
leading to increased shear stress during blinking, as seen in cases of dry eye. Some manufacturers claim that the properties of their CLs are specifically crafted to retain
hydration, ensuring comfort even for individuals experiencing CL discomfort and dry eye symptoms. This study focuses on evaluating and comparing the properties of two silicone hydrogel (SiHy) materials, Kalifilcon A and Senofilcon A. Three key aspects were examined: i) the hydration (WCwear) of CLs after six hours of wear, compared to the CL equilibrium water content (EWC), ii) the in-vitro coefficient of friction of the CL surface at WCwear, and iii) the in-vitro dehydration profile from EWC down to WCwear, under conditions of temperature and humidity mimicking typical wear conditions. The results suggest that WCwear is lower than EWC by a few percentage points for both materials, in-vitro friction is slightly higher for the SiHy Kalifilcon A than for the SiHy Senofilcon A, and the SiHy Kalifilcon A dehydration profile shows the typical behavior of hydrogels, in contrast to Senofilcon A, which shows the typical behavior of SiHys
AutoEncoders for per-lumisection data quality monitoring at CMS
Get PDFThe monitoring of data quality is crucial both online, during the data taking, to promptly spot issues and act on them, and offline, to provide analysts with datasets that are cleaned against the occasional failures that may have crept in. Typically, data quality monitoring (DQM) is performed by shifters who look at a set of integrated quantities, compare them with reference histograms, and, based on their experience and training, assign quality flags. Recently CMS has developed the possibility of producing DQM plots per-lumisection, where a lumisection is a time unit corresponding to about 23 s of data taking. To analyze per-lumisection data, a manual approach would be prohibitive due to the high number of lumisections, therefore an automated one would be preferable. In this work, the first use in CMS of AutoEncoders to perform anomaly detection on per-lumisection data, specifically for quantities associated with jets and missing transverse energy, is presented. The technique developed allows the detection of anomalies at the level of individual
lumisections, which might be overlooked when examining integrated quantities, and serves as a proof of concept regarding the efficacy of this and similar approaches
FPGA inference of Deep Neural Network-based trigger algorithms at Colliders
Get PDFExperimental particle physics demands a sophisticated trigger and acquisition system capable to efficiently retain the collisions of interest for further investigation. Heterogeneous computing with the employment of FPGA cards may emerge as a trending technology for the triggering strategy of the upcoming high luminosity program of the Large Hadron Collider at CERN. In this context, this work presents two machine-learning algorithms for selecting events where neutral long-lived particles decay within the detector volume studying their accuracy and inference time when accelerated on commercially available Xilinx FPGA accelerator cards. The inference time is also compared with a CPU- and GPU-based hardware setup. The results indicate that all tested architectures fit within the accuracy and
latency requirements of a second-level trigger farm and that exploiting accelerator technologies for real-time processing of particle-physics collisions is a promising research field that deserves additional investigations, in particular with machinelearning models with a large number of trainable parameters
XPE Gas Pixel Detectors characterization using the X-ray Calibration Facility
Get PDFThe Imaging X-ray Polarimetry Explorer (IXPE) is a space mission launched on 9 December 2021 (collaboration NASA and ASI) to measure the linear polarization of different astrophysical sources over the photon energy range 2-8 keV.
The heart of IXPE Detector Unit, and of future polarization-aimed missions, is the Gas Pixel Detector. These detectors can be calibrated and characterized using the X-ray Calibration Facility, XCF, available at the Physics Department of the University of Torino. The XCF allows us to study X-rays at different energies with different spatial and polarization configurations. Initially conceived as a calibration source to qualify Gas Pixel Detectors, the XCF will support R&D programs of innovative position- energy- and polarization-sensitive X-ray detectors
Multi-meson photoproduction off the proton: Recent results from the CBELSA/TAPS experiment
Get PDFThe final state pπ0π0 was analysed in photoproduction data of the CBELSA/TAPS experiment. Measurement with linearly polarized photons and a transversely polarized butanol target allowed the extraction of single and double polarization observables. The observables entered the BnGa-PWA, where branching ratios of resonances were determined. Systematic differences in the decay branching ratios of N∗ and Δ∗ resonances via excited hadrons hint at the internal structure of these states