752 research outputs found
Distortions of Experimental Muon Arrival Time Distributions of Extensive Air Showers by the Observation Conditions
Event-by-event measured arrival time distributions of Extensive Air Shower
(EAS) muons are affected and distorted by various interrelated effects which
originate from the time resolution of the timing detectors, from fluctuations
of the reference time and the number (multiplicity) of detected muons spanning
the arrival time distribution of the individual EAS events. The origin of these
effects is discussed, and different correction procedures, which involve
detailed simulations, are proposed and illustrated. The discussed distortions
are relevant for relatively small observation distances (R < 200 m) from the
EAS core. Their significance decreases with increasing observation distance and
increasing primary energies. Local arrival time distributions which refer to
the observed arrival time of the first local muon prove to be less sensitive to
the mass of the primary. This feature points to the necessity of arrival time
measurements with additional information on the curvature of the EAS disk.Comment: 10 pages, 6 figures, accepted for publication in Astroparticle
Physic
Features of Muon Arrival Time Distributions of High Energy EAS at Large Distances From the Shower Axis
In view of the current efforts to extend the KASCADE experiment
(KASCADE-Grande) for observations of Extensive Air Showers (EAS) of primary
energies up to 1 EeV, the features of muon arrival time distributions and their
correlations with other observable EAS quantities have been scrutinised on
basis of high-energy EAS, simulated with the Monte Carlo code CORSIKA and using
in general the QGSJET model as generator. Methodically various correlations of
adequately defined arrival time parameters with other EAS parameters have been
investigated by invoking non-parametric methods for the analysis of
multivariate distributions, studying the classification and misclassification
probabilities of various observable sets. It turns out that adding the arrival
time information and the multiplicity of muons spanning the observed time
distributions has distinct effects improving the mass discrimination. A further
outcome of the studies is the feature that for the considered ranges of primary
energies and of distances from the shower axis the discrimination power of
global arrival time distributions referring to the arrival time of the shower
core is only marginally enhanced as compared to local distributions referring
to the arrival of the locally first muon.Comment: 24 pages, Journal Physics G accepte
On the Discovery of the GZK Cut-off
The recent claim of the '5 sigma' observation of the Greisen and Zatzepin and
Kuzmin cut-off by the HiRes group based on their nine years data is a
significant step toward the eventual solution of the one of the most intriguing
questions which has been present in physics for more than forty years. However
the word 'significance' is used in the mentioned paper in the sense which is
not quite obvious. In the present paper we persuade that this claim is a little
premature.Comment: 10 page
On the energy of neutrinos from gamma ray bursts
Ultra high energy protons accelerated at the shocks causing gamma ray bursts
photoproduce pions, and then neutrinos in situ. I consider here the sources of
losses in this process, namely adiabatic and synchrotron losses by both pions
and muons. When the shocks under consideration are external, i.e., those
between the ejecta and the surrounding interstellar medium, I show that
neutrinos produced by pion decay are unaffected by losses; those produced by
muon decay, in the strongly beamed emission required by afterglow observations
of GRB 971214, are limited in energy, but still exceed 10^19 eV. In particular,
this means that ultra high energy neutrinos will be produced through
afterglows.Comment: to appear in The Astrophysical Journal. AASTEX LateX, 2 figure
Simulation of Ultra-High Energy Photon Propagation in the Geomagnetic Field
The identification of primary photons or specifying stringent limits on the
photon flux is of major importance for understanding the origin of ultra-high
energy (UHE) cosmic rays. We present a new Monte Carlo program allowing
detailed studies of conversion and cascading of UHE photons in the geomagnetic
field. The program named PRESHOWER can be used both as an independent tool or
together with a shower simulation code. With the stand-alone version of the
code it is possible to investigate various properties of the particle cascade
induced by UHE photons interacting in the Earth's magnetic field before
entering the Earth's atmosphere. Combining this program with an extensive air
shower simulation code such as CORSIKA offers the possibility of investigating
signatures of photon-initiated showers. In particular, features can be studied
that help to discern such showers from the ones induced by hadrons. As an
illustration, calculations for the conditions of the southern part of the
Pierre Auger Observatory are presented.Comment: 41 pages, 9 figures, added references in introduction, corrected
energy in row 1 of Table 3, extended caption of Table
The neutron 'thunder' accompanying the extensive air shower
Simulations show that neutrons are the most abundant component among
extensive air shower hadrons. However, multiple neutrons which appear with long
delays in neutron monitors nearby the EAS core ('neutron thunder') are mostly
not the neutrons of the shower, but have a secondary origin. The bulk of them
is produced by high energy EAS hadrons hitting the monitors. The delays are due
to the termalization and diffusion of neutrons in the moderator and reflector
of the monitor accompanied by the production of secondary gamma-quanta. This
conclusion raises the important problem of the interaction of EAS with the
ground, the stuff of the detectors and their environment since they have often
hydrogen containing materials like polyethilene in neutron monitors. Such
interaction can give an additional contribution to the signal in the EAS
detectors. It can be particularly important for the signals from scintillator
or water tank detectors at km-long distances from the EAS core where neutrons
of the shower become the dominant component after a few mcsec behind the EAS
front.Comment: 12 pages, 4 figures, accepted by J.Phys.G: Nucl.Part.Phy
Methodology for evaluating the radiological consequences of radioactive effluents released in normal operations. July 1979, Joint Report by the National Radiological Protection Board and the Commissariat a L'Energie Atomique.
Study of a mini-array for the Linsley effect in cosmic-ray air showers
The arrival-time distribution of shower particles far from the core has been measured as a function of shower axis distance at the Akeno Observatory by a cluster of 64 scintillators (total area 16 m2) located near the centre of the 1 km2 array. More than 3500 1 km2 array events and about 300 20 km2 array events have been analysed. The authors compare parameters tau (exponential fit to arrival times), sigma (conventional dispersion) and tr (rise time) for the specification of the spread in arrival times. From a measurement of time spread, the shower axis distance can be determined with an uncertainty of 25 to 30% with this detector system. The resulting uncertainty in shower size, including a 60% uncertainty in particle density measurement, is 120 to 140%. The resultant smearing of changes in slope of the frequency spectrum of incident showers is calculated. The smearing masks all but the gross changes in slope. The method may be useful for anisotropy studies, when a system for finding direction is included.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/49016/2/jgv15i1p113.pd
Learning to be Waste Wise
The Learning to be Waste Wise Activity Guide is a series of curriculum-linked activity packs written for the Waste Wise Schools Program. Each booklet covers a different topic including a general introduction to waste, the â3Rsâ (Reduce, Reuse and Recycle), âWormsâ and âCompostâ. The activities are designed to complement the schoolâs ongoing waste minimisation projects, and to support learning at every stage of a schoolâs Waste Wise journey. In turn, Waste Wise projects provide real life context to curriculum outcomes while directly involving students in their own learning.
By reinforcing Waste Wise principles through the curriculum in an engaging and practical way, teachers will find it easier to incorporate waste reduction practices in their school. In addition, the involvement of students and the modelling of positive behaviours, reinforces the environmental principles and curriculum outcomes.
The activities are designed to be fun; to promote life-long learning; to empower and enable students, teachers and the rest of the school community to take responsibility for their waste minimisation actions; to develop positive environmental values and to promote long-term behaviour change
The Extremely High Energy Cosmic Rays
Experimental results from Haverah Park, Yakutsk, AGASA and Fly's Eye are
reviewed. All these experiments work in the energy range above 0.1 EeV. The
'dip' structure around 3 EeV in the energy spectrum is well established by all
the experiments, though the exact position differs slightly. Fly's Eye and
Yakutsk results on the chemical composition indicate that the cosmic rays are
getting lighter over the energy range from 0.1 EeV to 10 EeV, but the exact
fraction is hadronic interaction model dependent, as indicated by the AGASA
analysis. The arrival directions of cosmic rays are largely isotropic, but
interesting features may be starting to emerge. Most of the experimental
results can best be explained with the scenario that an extragalactic component
gradually takes over a galactic population as energy increases and cosmic rays
at the highest energies are dominated by particles coming from extragalactic
space. However, identification of the extragalactic sources has not yet been
successful because of limited statistics and the resolution of the data.Comment: The review paper including 21 figures. 39 pages: To be published in
Journal of Physics
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