In this paper we examine nonradiative processes ~cross relaxation and energy migration! vital for the generation of blue avalanche emission in Tm:LiYF4 crystals subjected to radiation near 648 nm. Time-domain and temperature-dependent measurements indicate that two sequential cross-relaxation processes dominate the nonradiative decays of the G4 and H4 excited states in this crystal. The occurre...

When using avalanche photodiodes (APDs) in applications, temperature dependence of avalanche breakdown voltage is one of the performance parameters to be considered. Hence, novel materials developed for APDs require dedicated experimental studies. We have carried out such a study on thin Al1-x Ga x As0.56Sb0.44 p-i-n diode wafers (Ga composition from 0 to 0.15), plus measurements of avalanche g...

Snapback breakdown is the second order effect of avalanche breakdown in a device. Snapback occur when the excess supply voltage and high currents created flow through the device and become unstable. These two breakdowns are used to explain the concept of Vertical Impact Ionization MOSFET (IMOS) in its Equivalent Circuit Model. The equivalent circuit model design consists of MOS transistors that...

Single-photon detectors (SPDs) are the most sensitive instruments for light detection. In the near-infrared range, SPDs based on III–V compound semiconductor avalanche photodiodes have been extensively used during the past two decades for diverse applications due to their advantages in practicality including small size, low cost and easy operation. In the past decade, the rapid developments and...

We study a model of “organized” criticality, where a single avalanche propagates through an a priori static (i.e., organized) sandpile configuration. The latter is chosen according to an i.i.d. distribution from a Borel probability measure ρ on [0, 1]. The avalanche dynamics is driven by a standard toppling rule, however, we simplify the geometry by placing the problem on a directed, rooted tre...

ballast as a part of the railway system plays an important role in the operation of the railways and also has a great impact on repair and maintenance activities. hence most of the repair and maintenance activities in traditional railway systems are due to the defections in the ballast layer and therefore most of the maintenance budget is spent on repairing these defects. these repair and maint...

The GRASS system has been used to evaluate avalanche risk. This has been done by combining heterogeneous data. Val di Pejo, located in the north-western Trentino, an Italian alpine region which shows frequent and sometimes huge avalanche phenomena, has been selected as test area. A morphologic risk has been defined in those areas where the slope is between 28° and 55° for a minimum surface of a...