3,720 research outputs found
Search for Antimatter in Space with the Alpha Magnetic Spectrometer
The Alpha Magnetic Spectrometer (AMS) is a state of the art particle physics
experiment for the extraterrestrial study of antimatter, matter and missing
matter. AMS successfully completed the precursor STS91 Discovery flight (June
2nd-12th, 1998), completing 152 orbits at 52 degrees of latitude and about 400
km of height, collecting more than 100 million CR events. In this paper we
report on the first flight experience and we present preliminary results on the
search for nuclear antimatter. No antimatter nuclei with Z>=2 were detected. We
obtain a model dependent upper limit on the anti-He /He flux <1.14 10^^-6 In
the rigidity region between 1.6 to 20 GV we obtain a model independent,
conservative upper limit on anti-He /He flux <1.7 10^^-6 and <2.8 10^^-5 for
Z>2, improving the results of previous published searches performed with
stratospheric balloons.Comment: 1 tex file, 15 pages, 11 figures ps.gz file
Production networks and failure avalanches
Although standard economics textbooks are seldom interested in production
networks, modern economies are more and more based upon suppliers/customers
interactions. One can consider entire sectors of the economy as generalised
supply chains. We will take this view in the present paper and study under
which conditions local failures to produce or simply to deliver can result in
avalanches of shortage and bankruptcies across the network. We will show that a
large class of models exhibit scale free distributions of production and wealth
among firms and that metastable regions of high production are highly
localised
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