Efficient photon number detection with silicon avalanche photodiodes

We demonstrate an efficient photon number detector for visible wavelengths using a silicon avalanche photodiode. Under subnanosecond gating, the device is able to resolve up to four photons in an incident optical pulse. The detection efficiency at 600 nm is measured to be 73.8%, corresponding to an avalanche probability of 91.1% of the absorbed photons, with a dark count probability below 1.1x10^{-6} per gate. With this performance and operation close to room temperature, fast-gated silicon avalanche photodiodes are ideal for optical quantum information processing that requires single-shot photon number detection

IFKIS - a basis for managing avalanche risk in settlements and on roads in Switzerland

After the avalanche winter of 1999 in Switzerland, which caused 17&nbsp;deaths and damage of over CHF&nbsp;600&nbsp;mill. in buildings and on roads, the project IFKIS, aimed at improving the basics of organizational measures (closure of roads, evacuation etc.) in avalanche risk management, was initiated. <P style='line-height: 20px;'> The three main parts of the project were the development of a compulsory checklist for avalanche safety services, a modular education and training course program and an information system for safety services. The information system was developed in order to improve both the information flux between the national centre for avalanche forecasting, the Swiss Federal Institute for Snow and Avalanche Research SLF, and the local safety services on the one hand and the communication between avalanche safety services in the communities on the other hand. <P style='line-height: 20px;'> The results of this project make a valuable contribution to strengthening organizational measures in avalanche risk management and to closing the gaps, which became apparent during the avalanche winter of 1999. They are not restricted to snow avalanches but can also be adapted for dealing with other natural hazard processes and catastrophes

A new web-based system to improve the monitoring of snow avalanche hazard in France

International audienceSnow avalanche data in the French Alps and Pyrenees have been recorded for more than 100 years in several databases. The increasing amount of observed data required a more integrative and automated service. Here we report the comprehensive web-based Snow Avalanche Information System newly developed to this end for three important data sets: an avalanche chronicle (Enquete Permanente sur les Avalanches, EPA), an avalanche map (Carte de Localisation des Phenomenes d'Avalanche, CLPA) and a compilation of hazard and vulnerability data recorded on selected paths endangering human settlements (Sites Habites Sensibles aux Avalanches, SSA). These data sets are now integrated into a common database, enabling full interoperability between all different types of snow avalanche records: digitized geographic data, avalanche descriptive parameters, eyewitness reports, photographs, hazard and risk levels, etc. The new information system is implemented through modular components using Java-based web technologies with Spring and Hibernate frameworks. It automates the manual data entry and improves the process of information collection and sharing, enhancing user experience and data quality, and offering new outlooks to explore and exploit the huge amount of snow avalanche data available for fundamental research and more applied risk assessment