649 research outputs found
Low-noise design issues for analog front-end electronics in 130 nm and 90 nm CMOS technologies
Deep sub-micron CMOS technologies provide wellestablished solutions to the implementation of low-noise front-end electronics in various detector applications. The IC designers’ effort is presently shifting to 130 nm CMOS technologies, or even to the next technology node, to implement readout integrated circuits for silicon strip and pixel detectors, in view of future HEP applications. In this work the results of noise measurements carried out on CMOS devices in 130 nm and 90 nm commercial processes are presented. The behavior of the 1/f and white noise terms is studied as a function of the device polarity and of the gate length and width. The study is focused on low current density applications where devices are biased in weak or moderate inversion. Data obtained from the measurements provide a powerful tool to establish design criteria in nanoscale CMOS processes for detector front-ends in LHC upgrades
MAPS in 130 nm triple well CMOS technology for HEP applications
Deep N-well CMOS monolithic active pixel sensors (DNWMAPS) represent an alternative approach to signal processing in pixellated detectors for high energy physics experiments. Based on different resolution constraints, two prototype MAPS, suitable for applications requiring different detector pitch, have been developed and fabricated in 130 nm triple well CMOS technology. This work presents experimental results from the characterization of some test structures together with TCAD and Monte Carlo simulations intended to study the device properties in terms of charge diffusion and charge sharing among pixels
Deep R-band counts of z~3 Lyman break galaxy candidates with the LBT
Aims. We present a deep multiwavelength imaging survey (UGR) in 3 different
fields, Q0933, Q1623, and COSMOS, for a total area of ~1500arcmin^2. The data
were obtained with the Large Binocular Camera on the Large Binocular Telescope.
Methods. To select our Lyman break galaxy (LBG) candidates, we adopted the well
established and widely used color-selection criterion (U-G vs. G-R). One of the
main advantages of our survey is that it has a wider dynamic color range for
U-dropout selection than in previous studies. This allows us to fully exploit
the depth of our R-band images, obtaining a robust sample with few interlopers.
In addition, for 2 of our fields we have spectroscopic redshift information
that is needed to better estimate the completeness of our sample and interloper
fraction. Results. Our limiting magnitudes reach 27.0(AB) in the R band
(5\sigma) and 28.6(AB) in the U band (1\sigma). This dataset was used to derive
LBG candidates at z~3. We obtained a catalog with a total of 12264 sources down
to the 50% completeness magnitude limit in the R band for each field. We find a
surface density of ~3 LBG candidates arcmin^2 down to R=25.5, where
completeness is >=95% for all 3 fields. This number is higher than the original
studies, but consistent with more recent samples.Comment: in press by A&A, full LBG candidates' catalog will be available in
electronic form at the CD
Variable stars and stellar populations in Andromeda XXI: II. Another merged galaxy satellite of M31?
B and V time-series photometry of the M31 dwarf spheroidal satellite
Andromeda XXI (And XXI) was obtained with the Large Binocular Cameras at the
Large Binocular Telescope. We have identified 50 variables in And XXI, of which
41 are RR Lyrae stars (37 fundamental-mode RRab, and 4 first-overtone RRc,
pulsators) and 9 are Anomalous Cepheids (ACs). The average period of the RRab
stars ( = 0.64 days) and the period-amplitude diagram place And~XXI in the
class of Oosterhoff II - Oosterhoff-Intermediate objects. From the average
luminosity of the RR Lyrae stars we derived the galaxy distance modulus of
(m-M)= mag, which is smaller than previous literature
estimates, although still consistent with them within 1 . The galaxy
color-magnitude diagram shows evidence for the presence of three different
stellar generations in And~XXI: 1) an old ( 12 Gyr) and metal poor
([Fe/H]=1.7 dex) component traced by the RR Lyrae stars; 2) a slightly
younger (10-6 Gyr) and more metal rich ([Fe/H]=1.5 dex) component populating
the red horizontal branch, and 3) a young age ( 1 Gyr) component with
same metallicity, that produced the ACs. Finally, we provide hints that And~XXI
could be the result of a minor merging event between two dwarf galaxies.Comment: accepted for publications in Ap
Allenamides Playing Domino: A Redox-Neutral Photocatalytic Synthesis of Functionalized 2-Aminofurans
A photoredox catalytic synthesis of functionalized 2-aminofurans is proposed starting from α-halo carbonyl substrates and N-allenamides. The protocol proves to be efficient and sustainable thanks to: i) the use of visible light as green energy source, ii) the redox-neutral nature of the transformation, allowing to avoid additives and strong oxidants, iii) the mild reaction conditions and the functional groups tolerance, iv) the low photocatalyst loading and the absence of excess reagents, v) the one-pot formation of three new bonds in a domino sequence. According to our mechanistic hypothesis, the transformation is configured as a double radical-polar crossover reaction, in which the photocatalyst is excited, oxidized and reduced twice for each molecule of 2-aminofuran produced. The novelty of the designed synthetic approach also lies in the use of N-allenamides as substrates, which, after the addition of the first electrophilic radical, preserve a further reactive π-system, making possible the addition of a second α-keto radical and enabling the installation of a keto functionality at a remote position. The good yields, the broad scope, and the possibility to further synthetically elaborate the obtained furans make this protocol particularly promising for the construction of useful products. (Figure presented.)
Redetermination of tetrakis(N,N-diethyldithiocarbamato)tin(IV)
The crystal structure of the title compound, [Sn(C5H10NS2)4], was originally determined by Harreld & Schlemper [Acta Cryst. (1971), B27, 1964–1969] using intensity data estimated from Weissenberg films. In comparison with the previous refinement, the current redetermination reveals anisotropic displacement parameters for all non-H atoms, localization of the H atoms, and higher precision of lattice parameters and interatomic distances. The complex features a distorted S6 octahedral coordination geometry for tin and a cis disposition of the monodentate dithiocarbamate ligands
Understanding light quanta: First quantization of the free electromagnetic field
The quantization of the electromagnetic field in vacuum is presented without
reference to lagrangean quantum field theory. The equal time commutators of the
fields are calculated from basic principles. A physical discussion of the
commutators suggest that the electromagnetic fields are macroscopic emergent
properties of more fundamental physical system: the photons
Characterizing faint galaxies in the reionization epoch: LBT confirms two L<0.2L* sources at z=6.4 behind the CLASH/Frontier Fields cluster MACS0717.5+3745
We report the LBT/MODS1 spectroscopic confirmation of two images of faint
Lyman alpha emitters at behind the Frontier Fields galaxy cluster
MACSJ0717.5+3745. A wide range of lens models suggests that the two images are
highly magnified, with a strong lower limit of mu>5. These are the faintest z>6
candidates spectroscopically confirmed to date. These may be also multiple
images of the same z=6.4 source as supported by their similar intrinsic
properties, but the lens models are inconclusive regarding this interpretation.
To be cautious, we derive the physical properties of each image individually.
Thanks to the high magnification, the observed near-infrared (restframe
ultraviolet) part of the spectral energy distributions and Ly-alpha lines are
well detected with S/N(m_1500)>~10 and S/N(Ly-alpha)~10-15. Adopting mu>5, the
absolute magnitudes, M_1500, and Ly-alpha fluxes, are fainter than -18.7 and
2.8x10^(-18)erg/s/cm2, respectively. We find a very steep ultraviolet spectral
slope beta=-3.0+/-0.5 (F_lambda=lambda^(beta)), implying that these are very
young, dust-free and low metallicity objects, made of standard stellar
populations or even extremely metal poor stars (age<~30Myr, E(B-V)=0 and
metallicity 0.0-0.2 Z/Zsolar). The objects are compact (< 1 kpc^(2)), and with
a stellar mass M* < 10^(8) M_solar. The very steep beta, the presence of the
Ly-alpha line and the intrinsic FWHM (<300 km/s) of these newborn objects do
not exclude a possible leakage of ionizing radiation. We discuss the
possibility that such faint galaxies may resemble those responsible for cosmic
reionization.Comment: Accepted by ApJL; 6 pages, 4 figures, 1 table, emulateapj forma
Real-Time Oil Leakage Detection on Aftermarket Motorcycle Damping System with Convolutional Neural Networks
In this work, we describe in detail how Deep Learning and Computer Vision can help to detect fault events of the AirTender system, an aftermarket motorcycle damping system component. One of the most effective ways to monitor the AirTender functioning is to look for oil stains on its surface. Starting from real-time images, AirTender is first detected in the motorbike suspension system, simulated indoor, and then, a binary classifier determines whether AirTender is spilling oil or not. The detection is made with the help of the Yolo5 architecture, whereas the classification is carried out with the help of a suitably designed Convolutional Neural Network, OilNet40. In order to detect oil leaks more clearly, we dilute the oil in AirTender with a fluorescent dye with an excitation wavelength peak of approximately 390 nm. AirTender is then illuminated with suitable UV LEDs. The whole system is an attempt to design a low-cost detection setup. An on-board device, such as a mini-computer, is placed near the suspension system and connected to a full hd camera framing AirTender. The on-board device, through our Neural Network algorithm, is then able to localize and classify AirTender as normally functioning (non-leak image) or anomaly (leak image)
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