Abstract
Earthquakes frequently occur in Japan. Even though countermeasures are thoroughly considered and well executed, earthquakes still impact facilities and experimental devices. The large ...relative displacements induced by an earthquake can damage beam pipe bellows and interfere with sub-detectors by causing the tolerance between them to disappear. Even magnet quenches have been triggered by induced voltages caused by the relative displacements between the superconducting solenoids (i.e., the detector solenoid and the compensating solenoids surrounding the final focus quadrupole magnets, or QCSs). In response, we installed acceleration sensors on the Belle II detector and mounted gap sensors on the QCSs to measure the relative displacements. These measurements enabled the characteristics of the earthquakes that have affected the Belle II detector to be analysed. Response spectrum analyses (RSAs) of the Belle II detector were conducted to evaluate the impact of earthquakes according to the ground motion measurements. We then compared the measurements to the RSA results, which led to an idea for a countermeasure.
Negative thermal expansion is an unusual phenomenon appearing in only a handful of materials, but pursuit and mastery of the phenomenon holds great promise for applications across disciplines and ...industries. Here we report use of x-ray spectroscopy and diffraction to investigate the 4f-electronic properties in Y-doped SmS and employ the Kondo volume collapse model to interpret the results. Our measurements reveal an unparalleled decrease of the bulk Sm valence by over 20% at low temperatures in the mixed-valent golden phase, which we show is caused by a strong coupling between an emergent Kondo lattice state and a large isotropic volume change. The amplitude and temperature range of the negative thermal expansion appear strongly dependent on the Y concentration and the associated chemical disorder, providing control over the observed effect. This finding opens avenues for the design of Kondo lattice materials with tunable, giant, and isotropic negative thermal expansion.
The surface detector array of the Telescope Array experiment Abu-Zayyad, T.; Aida, R.; Anderson, R. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2012, Letnik:
689
Journal Article
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Odprti dostop
The Telescope Array (TA) experiment, located in the western desert of Utah, USA, is designed for the observation of extensive air showers from extremely high energy cosmic rays. The experiment has a ...surface detector array surrounded by three fluorescence detectors to enable simultaneous detection of shower particles at ground level and fluorescence photons along the shower track. The TA surface detectors and fluorescence detectors started full hybrid observation in March, 2008. In this article we describe the design and technical features of the TA surface detector.
Previous measurements of the composition of Ultra-High Energy Cosmic Rays (UHECRs) made by the High Resolution Fly’s Eye (HiRes) and Pierre Auger Observatory (PAO) are seemingly contradictory, but ...utilize different detection methods, as HiRes was a stereo detector and PAO is a hybrid detector. The five year Telescope Array (TA) Middle Drum hybrid composition measurement is similar in some, but not all, respects in methodology to PAO, and good agreement is evident between data and a light, largely protonic, composition when comparing the measurements to predictions obtained with the QGSJetII-03 and QGSJet-01c models. These models are also in agreement with previous HiRes stereo measurements, confirming the equivalence of the stereo and hybrid methods. The data is incompatible with a pure iron composition, for all models examined, over the available range of energies. The elongation rate and mean values of Xmax are in good agreement with Pierre Auger Observatory data. This analysis is presented using two methods: data cuts using simple geometrical variables and a new pattern recognition technique.
We present new spectroscopic and photometric data of the Type Ibn supernovae 2006jc, 2000er and 2002ao. We discuss the general properties of this recently proposed supernova family, which also ...includes SN 1999cq. The early-time monitoring of SN 2000er traces the evolution of this class of objects during the first few days after the shock breakout. An overall similarity in the photometric and spectroscopic evolution is found among the members of this group, which would be unexpected if the energy in these core-collapse events was dominated by the interaction between supernova ejecta and circumstellar medium. Type Ibn supernovae appear to be rather normal Type Ib/c supernova explosions which occur within a He-rich circumstellar environment. SNe Ibn are therefore likely produced by the explosion of Wolf–Rayet progenitors still embedded in the He-rich material lost by the star in recent mass-loss episodes, which resemble known luminous blue variable eruptions. The evolved Wolf–Rayet star could either result from the evolution of a very massive star or be the more evolved member of a massive binary system. We also suggest that there are a number of arguments in favour of a Type Ibn classification for the historical SN 1885A (S-Andromedae), previously considered as an anomalous Type Ia event with some resemblance to SN 1991bg.
•The burst of air shower like events related lightning discharge.•The spatial distribution of high energy radiation from lightning was observed.•The shower reconstruction shows that the shower was ...initiated at a low altitude.
The Telescope Array (TA) experiment is designed to detect air showers induced by ultra high energy cosmic rays. The TA ground Surface particle Detector (TASD) observed several short-time bursts of air shower like events. These bursts are not likely due to chance coincidence between single shower events. The expectation of chance coincidence is less than 10−4 for five-year's observation. We checked the correlation between these bursts of events and lightning data, and found evidence for correlations in timing and position. Some features of the burst events are similar to those of a normal cosmic ray air shower, and some are not. On this paper, we report the observed bursts of air shower like events and their correlation with lightning.
Pressure dependence of the Ce valence in CeCu(2)Ge(2) has been measured up to 24 GPa at 300 K and to 17 GPa at 18-20 K using x-ray absorption spectroscopy in the partial fluorescence yield. A smooth ...increase of the Ce valence with pressure is observed across the two superconducting (SC) regions without any noticeable irregularity. The chemical pressure dependence of the Ce valence was also measured in Ce(Cu(1-x)Ni(x))(2)Si(2) at 20 K. A very weak, monotonic increase of the valence with x was observed, without any significant change in the two SC regions. Within experimental uncertainties, our results show no evidence for the valence transition with an abrupt change in the valence state near the SC II region, challenging the valence-fluctuation mediated superconductivity model in these compounds at high pressure and low temperature.
Interatomic Coulombic decay (ICD) from an Auger-final dicationic state is observed in the Ar dimer. A 2p inner-shell vacancy created by photoionization is replaced with 3s and 3p vacancies via ...intra-atomic Auger decay. The Auger-final dicationic state is subject to ICD in which one of the 3p electrons in the same Ar atom fills the 3s vacancy while one of the 3p electrons from the neighboring Ar atom is emitted as an ICD electron. This ICD process is unambiguously identified by electron-ion-ion coincidence spectroscopy in which the kinetic energy of the ICD electron and the kinetic energy release between Ar+ and Ar2+ are measured in coincidence.
The death of massive stars produces a variety of supernovae, which are linked to the structure of the exploding stars. The detection of several precursor stars of type II supernovae has been reported ...(see, for example, ref. 3), but we do not yet have direct information on the progenitors of the hydrogen-deficient type Ib and Ic supernovae. Here we report that the peculiar type Ib supernova SN 2006jc is spatially coincident with a bright optical transient that occurred in 2004. Spectroscopic and photometric monitoring of the supernova leads us to suggest that the progenitor was a carbon-oxygen Wolf-Rayet star embedded within a helium-rich circumstellar medium. There are different possible explanations for this pre-explosion transient. It appears similar to the giant outbursts of luminous blue variable stars (LBVs) of 60-100 solar masses, but the progenitor of SN 2006jc was helium- and hydrogen-deficient (unlike LBVs). An LBV-like outburst of a Wolf-Rayet star could be invoked, but this would be the first observational evidence of such a phenomenon. Alternatively, a massive binary system composed of an LBV that erupted in 2004, and a Wolf-Rayet star exploding as SN 2006jc, could explain the observations.
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Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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