4,465 research outputs found
Dark Matter directional detection: comparison of the track direction determination
Several directional techniques have been proposed for a directional detection
of Dark matter, among others anisotropic crystal detectors, nuclear emulsion
plates, and low-pressure gaseous TPCs. The key point is to get access to the
initial direction of the nucleus recoiling due to the elastic scattering by a
WIMP. In this article, we aim at estimating, for each method, how the
information of the recoil track initial direction is preserved in different
detector materials. We use the SRIM simulation code to emulate the motion of
the first recoiling nucleus in each material. We propose the use of a new
observable, D, to quantify the preservation of the initial direction of the
recoiling nucleus in the detector. We show that in an emulsion mix and an
anisotropic crystal, the initial direction is lost very early, while in a
typical TPC gas mix, the direction is well preserved.Comment: 9 pages, 5 figure
Xylosandrus compactus (Coleoptera : Curculionidae : Scolytinae), a new pest of Swietenia macrophylla in the peruvian Amazonia
Lonchophorellus scylla Clark, 1989 (Coleoptera : Curculionidae) nueva plaga de la guayaba (Psidium guayava L., Myrtaceae)
Atteva punctella Cramer (Lepidoptera : Yponomeutidae), plaga de Simarouba amara Aubl. (Simaroubaceae), en Peru
Probe of Lorentz Invariance Violation effects and determination of the distance of PG 1553+113
The high frequency peaked BL Lac object PG 1553+113 underwent a flaring event
in 2012. The High Energy Stereoscopic System (H.E.S.S.) observed this source
for two consecutive nights at very high energies (VHE, 100~GeV). The data
show an increase of a factor of three of the flux with respect to archival
measurements with the same instrument and hints of intra-night variability. The
data set has been used to put constraints on possible Lorentz invariance
violation (LIV), manifesting itself as an energy dependence of the velocity of
light in vacuum, and to set limits on the energy scale at which Quantum Gravity
effects causing LIV may arise. With a new method to combine H.E.S.S. and Fermi
large area telescope data, the previously poorly known redshift of PG 1555+113
has been determined to be close to the value derived from optical measurements.Comment: 2014 Fermi Symposium proceedings - eConf C14102.
NcorpiN : A software for N-body integration in collisional and fragmenting systems
NcorpiN is a -body software developed for the time-efficient
integration of collisional and fragmenting systems of planetesimals or moonlets
orbiting a central mass. It features a fragmentation model, based on crater
scaling and ejecta models, able to realistically simulate a violent impact. The
user of NcorpiN can choose between four different built-in modules
to compute self-gravity and detect collisions. One of these makes use of a
mesh-based algorithm to treat mutual interactions in time.
Another module, much more efficient than the standard Barnes-Hut tree code, is
a tree-based algorithm called FalcON. It relies on fast
multipole expansion for gravity computation and we adapted it to collision
detection as well. Computation time is reduced by building the tree structure
using a three-dimensional Hilbert curve. For the same precision in mutual
gravity computation, NcorpiN is found to be up to 25 times faster
than the famous software REBOUND. NcorpiN is written entirely in
the C language and only needs a C compiler to run. A python add-on, that
requires only basic python libraries, produces animations of the simulations
from the output files. The name NcorpiN, reminding of a scorpion,
comes from the French -corps, meaning -body, and from the mathematical
notation , due to the running time of the software being almost
linear in the total number of moonlets. NcorpiN is designed
for the study of accreting or fragmenting disks of planetesimal or moonlets. It
detects collisions and computes mutual gravity faster than REBOUND, and unlike
other -body integrators, it can resolve a collision by fragmentation. The
fast multipole expansions are implemented up to order six to allow for a high
precision in mutual gravity computation.Comment: 29 pages, 6 figure
Produccion y comercializacion de la larva de Rhynchophorus palmarum (Coleoptera : Dryophtoridae) en la Amazonia peruana
Determination of guidance values for closed landfill gas emissions
International audienceIn order to promote active landfill gas collection and treatment or natural attenuation, it is necessary to identify trigger values concerning landfill gas emissions in the preliminary stage of a risk assessment. The determination of these values is the first goal of a work which includes a large regulation review and the study of a generic inhalation exposure scenario for the most common reuse of French Municipal Solid Waste (MSW) landfill surface, namely a recreational area without residential buildings. The health risk levels of this scenario are lower than the usual levels and enable to determine trigger values for methane production rate. These results and the methane oxidation rate in the landfill cover allow for the determination of residual methane surface emission rates. The combination of these parameters with on-site specific measurements enables the promotion of natural attenuation or active landfill gas treatment
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