424 research outputs found
Después de la inundación, el desastre continúa: fraccionamiento nuevo mirador en Chilpancingo, Guerrero
El presente ensayo aborda el tema del desastre originado en la ciudad de Chilpancingo de los Bravo, capital del estado de Guerrero, en donde 1,295 viviendas fueron afectadas por los fenómenos meteorológicos Íngrid y Manuel, en septiembre de 2013. En el documento se analizan las acciones para reparar los daños, realizadas por el Estado, tomando como caso de estudio el Fraccionamiento Nuevo Mirador, un conjunto habitacional creado ex profeso para alojar a los afectados por el desastre. Considerando que los desastres no son producto de las manifestaciones de la naturaleza, sino que el causante principal es el ser humano, quien al intervenir el hábitat natural de manera inadecuada fomenta el riesgo de provocarlo, en este texto se hace una reflexión histórica, crítica y teórica sobre acciones implementadas por diversos actores políticos y sociales vinculados con el ordenamiento territorial de Chilpancingo, la segunda ciudad más poblada de la entidad (la primera es Acapulco, que cuenta con 725,549 habitantes en su área urbana),1 la cual se encuentra ubicada en una zona altamente sísmica, y en las inmediaciones del corredor de huracanes que anualmente afectan la costa del Pacífico mexicano, además de ser la sede económica-administrativa del gobierno estatal a la cual diariamente arriban miles de personas en busca de solucionar sus demandas sociales. Con el tiempo gran parte de esta población demandante se ha asentado en diversas partes de la ciudad, la mayoría no aptas para el desarrollo urbano por ser zonas con altas pendientes, susceptibles a deslaves e inundaciones
Background studies and shielding effects for the TPC detector of the CAST experiment
Sunset solar axions traversing the intense magnetic field of the CERN Axion
Solar Telescope (CAST) experiment may be detected in a Time Projection Chamber
(TPC) detector, as X-rays signals. These signals could be masked, however, by
the inhomogeneous background of materials in the experimental site. A detailed
analysis, based on the detector characteristics, the background radiation at
the CAST site, simulations and experimental results, has allowed us to design a
shielding which reduces the background level by a factor of ~4 compared to the
detector without shielding, depending on its position, in the energy range
between 1 and 10 keV. Moreover, this shielding has improved the homogeneity of
background measured by the TPC.Comment: 14 pages, 5 figures, accepted in New Journal of Physic
The CAST Time Projection Chamber
One of the three X-ray detectors of the CAST experiment searching for solar
axions is a Time Projection Chamber (TPC) with a multi-wire proportional
counter (MWPC) as a readout structure. Its design has been optimized to provide
high sensitivity to the detection of the low intensity X-ray signal expected in
the CAST experiment. A low hardware threshold of 0.8 keV is safely set during
normal data taking periods, and the overall efficiency for the detection of
photons coming from conversion of solar axions is 62 %. Shielding has been
installed around the detector, lowering the background level to 4.10 x 10^-5
counts/cm^2/s/keV between 1 and 10 keV. During phase I of the CAST experiment
the TPC has provided robust and stable operation, thus contributing with a
competitive result to the overall CAST limit on axion-photon coupling and mass.Comment: 19 pages, 11 figures and images, submitted to New Journal of Physic
CAST microbulk micromegas in the Canfranc Underground Laboratory
During the last taking data campaigns of the CAST experiment, the micromegas
detectors have achieved background levels of keVcms between 2 and 9 keV. This performance has
been possible thanks to the introduction of the microbulk technology, the
implementation of a shielding and the development of discrimination algorithms.
It has motivated new studies towards a deeper understanding of CAST detectors
background. One of the working lines includes the construction of a replica of
the set-up used in CAST by micromegas detectors and its installation in the
Canfranc Underground Laboratory. Thanks to the comparison between the
performance of the detectors underground and at surface, shielding upgrades,
etc, different contributions to the detectors background have been evaluated.
In particular, an upper limit keVcms
for the intrinsic background of the detector has been obtained. This work means
a first evaluation of the potential of the newest micromegas technology in an
underground laboratory, the most suitable environment for Rare Event Searches.Comment: 6 pages, 8 figures. To appear in the proceedings of the 2nd
International Conference on Technology and Instrumentation for Particle
Physics (TIPP 2011
Low Background Micromegas in CAST
Solar axions could be converted into x-rays inside the strong magnetic field
of an axion helioscope, triggering the detection of this elusive particle. Low
background x-ray detectors are an essential component for the sensitivity of
these searches. We report on the latest developments of the Micromegas
detectors for the CERN Axion Solar Telescope (CAST), including technological
pathfinder activities for the future International Axion Observatory (IAXO).
The use of low background techniques and the application of discrimination
algorithms based on the high granularity of the readout have led to background
levels below 10 counts/keV/cm/s, more than a factor 100 lower than
the first generation of Micromegas detectors. The best levels achieved at the
Canfranc Underground Laboratory (LSC) are as low as 10
counts/keV/cm/s, showing good prospects for the application of this
technology in IAXO. The current background model, based on underground and
surface measurements, is presented, as well as the strategies to further reduce
the background level. Finally, we will describe the R&D paths to achieve
sub-keV energy thresholds, which could broaden the physics case of axion
helioscopes.Comment: 6 pages, 3 figures, Large TPC Conference 2014, Pari
A Micromegas-based low-background x-ray detector coupled to a slumped-glass telescope for axion research
We report on the design, construction and operation of a low background x-ray
detection line composed of a shielded Micromegas (micromesh gaseous structure)
detector of the microbulk technique. The detector is made from radiopure
materials and is placed at the focal point of a ~5 cm diameter, 1.3 m
focal-length, cone-approximation Wolter I x-ray telescope (XRT) comprised of
thermally-formed (or "slumped") glass substrates deposited with multilayer
coatings. The system has been conceived as a technological pathfinder for the
future International Axion Observatory (IAXO), as it combines two of the
techniques (optic and detector) proposed in the conceptual design of the
project. It is innovative for two reasons: it is the first time an x-ray optic
has been designed and fabricated specifically for axion research, and the first
time a Micromegas detector has been operated with an x-ray optic. The line has
been installed at one end of the CERN Axion Solar Telescope (CAST) magnet and
is currently looking for solar axions. The combination of the XRT and
Micromegas detector provides the best signal-to-noise ratio obtained so far by
any detection system of the CAST experiment with a background rate of
5.410counts per hour in the energy region-of-interest and
signal spot area.Comment: 21 pages, 16 figure
Towards a new generation axion helioscope
We study the feasibility of a new generation axion helioscope, the most
ambitious and promising detector of solar axions to date. We show that large
improvements in magnetic field volume, x-ray focusing optics and detector
backgrounds are possible beyond those achieved in the CERN Axion Solar
Telescope (CAST). For hadronic models, a sensitivity to the axion-photon
coupling of \gagamma\gtrsim {\rm few} \times 10^{-12} GeV is
conceivable, 1--1.5 orders of magnitude beyond the CAST sensitivity. If axions
also couple to electrons, the Sun produces a larger flux for the same value of
the Peccei-Quinn scale, allowing one to probe a broader class of models. Except
for the axion dark matter searches, this experiment will be the most sensitive
axion search ever, reaching or surpassing the stringent bounds from SN1987A and
possibly testing the axion interpretation of anomalous white-dwarf cooling that
predicts of a few meV. Beyond axions, this new instrument will probe
entirely unexplored ranges of parameters for a large variety of axion-like
particles (ALPs) and other novel excitations at the low-energy frontier of
elementary particle physics.Comment: 37 pages, 11 figures, accepted for publication in JCA
Probing the axion-nucleon coupling with the next generation of axion helioscopes
A finite axion–nucleon coupling, nearly unavoidable for QCD axions, leads to the production of axions via the thermal excitation and subsequent de-excitation of 57Fe isotopes in the sun. We revise the solar bound on this flux adopting the up to date emission rate, and investigate the sensitivity of the proposed International Axion Observatory IAXO and its intermediate stage BabyIAXO to detect these axions. We compare different realistic experimental options and discuss the model dependence of the signal. Already BabyIAXO has sensitivity far beyond previous solar axion searches via the nucleon coupling and IAXO can improve on this by more than an order of magnitude
The International Axion Observatory (IAXO)
The International Axion Observatory (IAXO) is a new generation axion
helioscope aiming at a sensitivity to the axion-photon coupling of a few
10 GeV, i.e. 1 - 1.5 orders of magnitude beyond the one currently
achieved by CAST. The project relies on improvements in magnetic field volume
together with extensive use of x-ray focusing optics and low background
detectors, innovations already successfully tested in CAST. Additional physics
cases of IAXO could include the detection of electron-coupled axions invoked to
solve the white dwarfs anomaly, relic axions, and a large variety of more
generic axion-like particles (ALPs) and other novel excitations at the
low-energy frontier of elementary particle physics. This contribution is a
summary of our paper [1] to which we refer for further details.Comment: 4 pages, 2 figures. To appear in the proceedings of the 7th Patras
Workshop on Axions, WIMPs and WISPs, Mykonos, Greece, 201
El Nuevo Historicismo aplicado al cómic egipcio
La novel·la gràfica per adults al món àrab és tot un fenomen que ha augmentat significativament el seu volum de produccions a partir de les conegudes "Primaveres Àrabs" l'any 2011. La història contemporània egípcia ens permet conèixer el antecedents i l'actualitat dels fets revolucionaris que van expulsar a Hosni Mubarak. A partir de les vinyetes que creen els joves artistes podem copsar la realitat sociopolítica del país.La novela gráfica para adultos en el mundo árabe es todo un fenómeno que ha aumentado significativamente su volumen de producciones a partir de las conocidas "Primaveras Árabes" en el año 2011. La historia contemporánea egipcia nos permite conocer los antecedentes y la actualidad de los hechos revolucionarios que depusieron a Hosni Mubarak. A partir de las viñetas que crean los jóvenes artistas podemos ver la realidad sociopolítica del país.The Graphic Novel for adults in the Arab world it's a phenomenon which the volume of productions has increased significantly as from the known "Arab Springs" in the 2011. The Egyptian contemporary history allow us to know the backwards and afterwards of the revolutionary facts that deposed Hosni Mubarak. From the cartoons created by young artist we can approach to the socio-political reality of the country
- …