4,129 research outputs found
Performance of resistive plate chambers for the muon detection at CMS
The latest results, still preliminary, of tests dedicated to study the performance of Resistive Plate Chamber for the CMS experiment are presented. Full efficiency with a 2 ns time resolution in conditions of incident flux up to 2 kHz/cm2 has been obtained. Detector uniformity has been studied and found to be well within the constraints due to the large surfaces used in the experiment. An aging test is currently being carried out and shows no significant performance variation with time
Long-term performance of double gap resistive plate chambers under gamma irradiation
In this paper, we describe a dedicated test to study possible long-term aging effects on Resistive Plate Chambers (RPCs). A double gap detector was operated under gamma irradiation for a period approximately equal to 10 years of LHC in the CMS-barrel region: an integrated dose of about and a total charge of about gap were accumulated on the chamber. The results show no relevant aging effect. Also the RPC sensitivity to gamma energies is measured
Artificial membranes biomimicking pit vipers' thermal sensing
Artificial membranes that are sensitive to temperature are needed in robotics to augment interactions with humans and the environment, and in bioengineering to improve prosthetic limbs. Existing flexible sensors achieved sensitivities of <100 mK, albeit within narrow (<5 K) temperature ranges. Other flexible devices, working in wider temperature ranges, exhibit orders of magnitude poorer responses. However, much more versatile and temperature sensitive membranes are found in animals such as pit vipers, whose pit membranes have the highest sensitivity in nature and are used to locate warm-blooded preys at distance. Here, we show that pectin films mimic the sensing mechanism of pit membranes and parallel their record performance. These films map temperature on surfaces with a sensitivity of <10 mK in a wide temperature range (40 K) and detect warm bodies at distance
Time-frequency mapping of two-colour photoemission driven by harmonic radiation
The use of few-femtosecond, extreme ultraviolet (XUV) pulses, produced by
high-order harmonic generation, in combination with few-femtosecond infrared
(IR) pulses in pump-probe experiments has great potential to disclose ultrafast
dynamics in molecules, nanostructures and solids. A crucial prerequisite is a
reliable characterization of the temporal properties of the XUV and IR pulses.
Several techniques have been developed. The majority of them applies phase
reconstruction algorithms to a photoelectron spectrogram obtained by ionizing
an atomic target in a pump-probe fashion. If the ionizing radiation is a single
harmonic, all the information is encoded in a two-color two-photon signal
called sideband (SB). In this work, we present a simplified model to interpret
the time-frequency mapping of the SB signal and we show that the temporal
dispersion of the pulses directly maps onto the shape of its spectrogram.
Finally, we derive an analytical solution, which allows us to propose a novel
procedure to estimate the second-order dispersion of the XUV and IR pulses in
real time and with no need for iterative algorithms
Biomimetic temperature-sensing layer for artificial skins
Artificial membranes that are sensitive to temperature are needed in robotics to augment interactions with humans and the environment and in bioengineering to improve prosthetic limbs. Existing flexible sensors achieved sensitivities of <100 millikelvin and large responsivity, albeit within narrow (<5 kelvin) temperature ranges. Other flexible devices, working in wider temperature ranges, exhibit orders of magnitude poorer responses. However, much more versatile and temperature-sensitive membranes are present in animals such as pit vipers, whose pit membranes have the highest sensitivity and responsivity in nature and are used to locate warm-blooded prey at distance. We show that pectin films mimic the sensing mechanism of pit membranes and parallel their record performances. These films map temperature on surfaces with a sensitivity of at least 10 millikelvin in a wide temperature range (45 kelvin), have very high responsivity, and detect warm bodies at distance. The produced material can be integrated as a layer in artificial skin platforms and boost their temperature sensitivity to reach the best biological performance
Novel beamline for attosecond transient reflection spectroscopy in a sequential two-foci geometry
We present an innovative beamline for extreme ultraviolet (XUV)-infrared (IR)
pump-probe reflection spectroscopy in solids with attosecond temporal
resolution. The setup uses an actively stabilized interferometer, where
attosecond pulse trains or isolated attosecond pulses are produced by
high-order harmonic generation in gases. After collinear recombination, the
attosecond XUV pulses and the femtosecond IR pulses are focused twice in
sequence by toroidal mirrors, giving two spatially separated interaction
regions. In the first region, the combination of a gas target with a
time-of-flight spectrometer allows for attosecond photoelectron spectroscopy
experiments. In the second focal region, an XUV reflectometer is used for
attosecond transient reflection spectroscopy (ATRS) experiments. Since the two
measurements can be performed simultaneously, precise pump-probe delay
calibration can be achieved, thus opening the possibility for a new class of
attosecond experiments on solids. Successful operation of the beamline is
demonstrated by the generation and characterization of isolated attosecond
pulses, the measurement of the absolute reflectivity of SiO2, and by performing
simultaneous photoemission/ATRS in Ge.Comment: 18 pages, 9 figure
Default and Control Networks Connectivity Dynamics Track the Stream of Affect at Multiple Timescales
In everyday life, the stream of affect results from the interaction between past experiences, expectations and the unfolding of events. How the brain represents the relationship between time and affect has been hardly explored, as it requires modeling the complexity of everyday life in the laboratory setting. Movies condense into hours a multitude of emotional responses, synchronized across subjects and characterized by temporal dynamics alike real-world experiences. Here, we use time-varying intersubject brain synchronization and real-time behavioral reports to test whether connectivity dynamics track changes in affect during movie watching. The results show that polarity and intensity of experiences relate to the connectivity of the default mode and control networks and converge in the right temporoparietal cortex. We validate these results in two experiments including four independent samples, two movies and alternative analysis workflows. Finally, we reveal chronotopic connectivity maps within the temporoparietal and prefrontal cortex, where adjacent areas preferentially encode affect at specific timescales
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