753 research outputs found
AMS02 results after 4 years of data taking on the International Space Station
The AMS02 experiment is taking data on the International Space Station since May, 19, 2011. This report summarizes the key results published or presented in public conferences using the data collected in the first 4 years of the mission, trying to interpret them in terms of the latest models of Cosmic Ray (CR) propagation. In particular the fluxes of primary CR, like proton, Helium and Carbon, or of secondaries like Lithium and Boron, can be used to constraint the models and compare them with the observed anti-proton flux, to see if hints of Dark Matter (DM) can be identified. The same can be done in the lepton sector by looking at electrons and positrons. In the near future AMS02 will continue the observation of light nuclei, including isotopes like Deuterium, He-3 and He-4, and of anti-nuclei, like anti-Deuterium and anti-Helium, which represent, together with anti-protons and positrons, the golden channels in which to look for eventual Dark Matter or antimatter signals
Begging and parental care in relation to offspring need and condition in the barn swallow (Hirundo rustica)
Parents are selected to maximize their fitness by allocating
care among their progeny in relation to the differential reproductive
value of offspring. Nestlings have been hypothesized to
signal need for parental care reliably through their begging behavior,
but offspring condition as reflected by their reproductive value may
likewise affect begging and hence provisioning. We assessed the relative
importance of need and condition in determining begging behavior
and feeding rate of nestling barn swallows (Hirundo rustica)
through short-term starvation, a challenge to their immune system
with a foreign antigen negatively affecting condition, and brood size
manipulation. Food deprivation but not condition or brood size
manipulation increased nestling begging rate. Parents fed offspring
depending on both need and condition but only when feeding broods
that were reduced or of normal size. In enlarged broods, offspring
received less food per capita than in reduced broods, and parents
did not discriminate among nestlings relative to their need or condition.
Thus, nestlings signal their need by increased solicitation.
Parents allocate food to offspring dependent on both need and condition,
with these effects depending on parental workload as determined
by experimental brood size
Results on Multiple Coulomb Scattering from 12 and 20 GeV electrons on Carbon targets
Multiple scattering effects of 12 and 20 GeV electrons on 8 and 20 mm
thickness carbon targets have been studied with high-resolution silicon
microstrip detectors of the UA9 apparatus at the H8 line at CERN. Comparison of
the scattering angle between data and GEANT4 simulation shows excellent
agreement in the core of the distributions leaving some residual disagreement
in the tails.Comment: 14 pages, 16 figures. Updated to match published versio
The electromagnetic calorimeter of the AMS-02 experiment
The electromagnetic calorimeter (ECAL) of the AMS-02 experiment is a
3-dimensional sampling calorimeter, made of lead and scintillating fibers. The
detector allows for a high granularity, with 18 samplings in the longitudinal
direction, and 72 sampling in the lateral direction. The ECAL primary goal is
to measure the energy of cosmic rays up to few TeV, however, thanks to the fine
grained structure, it can also provide the separation of positrons from
protons, in the GeV to TeV region. A direct measurement of high energy photons
with accurate energy and direction determination can also be provided.Comment: Proceedings of SF2A conference 201
The FDM readout system for the TES bolometers of the SWIPE instrument on the balloon-borne LSPE experiment
We present the design and first tests of a prototype readout for the SWIPE instrument onboard the LSPE balloon-borne experiment. LSPE aims at measuring the linear polarization of the Cosmic Microwave Background (CMB) at large angular scales, to find the imprint of inflation on the B-mode CMB polarization. The SWIPE instrument hosts two focal planes hosting 163 TES Au/Mo spiderweb bolometers each, cooled at 0.3 K for the detection of microwave frequencies of 140, 220 and 240 GHz. To read all the detectors, a 16 channel frequency domain multiplexing readout system has been devised, consisting of LC resonators composed of custom Nb superconducting inductors and commercial SMD capacitors. A set-up consisting of 14 LC resonators shows that we can accommodate 16 channels in the frequency range between 200 kHz and 1.6 MHz, since the necessary line-widths can be achieved. A preliminary firmware for the generation and read-out of the biasing frequency comb is also discussed
Design and construction of new central and forward muon counters for CDF II
New scintillation counters have been designed and constructed for the CDF
upgrade in order to complete the muon coverage of the central CDF detector, and
to extend this coverage to larger pseudorapidity. A novel light collection
technique using wavelength shifting fibers, together with high quality
polystyrene-based scintillator resulted in compact counters with good and
stable light collection efficiency over lengths extending up to 320 cm. Their
design and construction is described and results of their initial performance
are reported.Comment: 20 pages, 15 figure
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