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•Recovering two independent components (ICs) using nonnegative matrix factorization.•The extraction of three significant features from segmented images.•The SVM prediction model ...provides a good classification rate 99.93%.•The classification of ICs into neutron or gamma one.•The neutron-gamma discrimination is achieved in mixed radiation field.
Recent developments of digital signal processing have played an effective role to achieve a fast and accurate neutron-gamma discrimination. Thus, we present in this research work, a novel method which combines supervised and unsupervised machine learning to perform the neutron-gamma discrimination task at the output of a stilbene organic scintillation detector. We propose a three steps procedure that highly qualifies the discrimination. First, the detector’s output signals are processed as mixtures of several unknown sources, through nonnegative matrix factorization algorithms. Second, the continuous wavelet transform is performed to characterize the recovered original sources. The resulting time-scale representation is considered as an image which is segmented in order to extract main features of neutron signals versus the gamma ones. The features are then used as input of a nonlinear support vector machine classifier to finally achieve the neutron-gamma discrimination in mixed radiation field. Furthermore, the proposed method provides the classification precision for each radiation.
Soils from a prospective phosphate mining area in the Hinda district of the Congo were analyzed using the ICP-MS technique in order to assess the environmental pollution and human health risks ...presented by potentially toxic elements (PTEs). The results showed that the mean concentrations of PTEs exceeded the global crustal average. Environmental pollution was assessed, showing the study area polluted by PTEs. Human health risk was also assessed, with the results showing the level of cancer risk greater for children than that for adults, indicating that children are more susceptible to the carcinogenic effects of PTEs than their adult counterparts.
The main objective of the present study was to determine the concentration of major and minor elements contained in soil and phosphate rock samples collected in the prospective phosphate mining area ...in Hinda district. Samples have been analyzed using k0-neutron activation method through the Moroccan Triga Mark II research reactor. The results showed Al, Fe, K, Mg, Mn and Na as major elements and As, Br, Cr, V and U as minor elements, including rare earth elements in soils and phosphate rocks. These results were compared with other studies reported worldwide. Pollution indicators have been determined to assess pollution status.
In the last years, some studies investigated dosimetric benefits of a free flattening filter for the photon mode in the radiotherapy field. This study aims to provide a theoretical study published ...and analysis of basic dosimetric properties for a Saturne 43 Linac head to implement free flattening filter beams clinically.
This is the first Monte Carlo study for the head of Saturne 43 with replacement flattening filter mode investigating beam dosimetric characteristics, including central axis absorbed doses, beam profiles and photon energy spectra. The later ones were analyzed for flattening filter and replacement flattening filter beams using BEAMnrc and DOSXYZnrc Monte Carlo codes for 10 × 10 cm
, 5 × 5 cm
and 2 × 2 cm
square field sizes.
A 3.94-fold increase of dose rate and electron contaminating increased by 246.4 % with the replacement flattening filter mode for field size of 10 × 10 cm
. Reduction was made by replacement flattening filter beam in the peripheral dose up to 30%, and the time was reduced more than 50 %.
Results obtained from our study revealed that some characteristic dosimetries such as the maximum increase in depth dose rate, decrease in out-of-depth dose, and reducing time can be beneficial for the unflattened beam to be used in the radiotherapy for the advanced techniques.
Abstract
Since 2015 the LIGO and Virgo interferometers have detected gravitational waves from
almost one hundred coalescences of compact objects (black holes and neutron stars). This article
presents ...the results of a search performed with data from the ANTARES telescope to identify
neutrino counterparts to the gravitational wave sources detected during the third LIGO/Virgo
observing run and reported in the catalogues GWTC-2, GWTC-2.1, and GWTC-3. This search is
sensitive to all-sky neutrinos of all flavours and of energies > 100 GeV,
thanks to the inclusion of both track-like events (mainly induced by
ν
μ
charged-current
interactions) and shower-like events (induced by other interaction types). Neutrinos are selected
if they are detected within ± 500 s from the GW merger and with a reconstructed
direction compatible with its sky localisation. No significant excess is found for any of the 80
analysed GW events, and upper limits on the neutrino emission are derived. Using the information
from the GW catalogues and assuming isotropic emission, upper limits on the total energy
E
tot,
ν
emitted as neutrinos of all flavours and on the ratio
f
ν
=
E
tot,
ν
/
E
GW
between neutrino and GW emissions are also computed. Finally, a stacked
analysis of all the 72 binary black hole mergers (respectively the 7 neutron star-black hole
merger candidates) has been performed to constrain the typical neutrino emission within this
population, leading to the limits:
E
tot,
ν
< 4.0 × 10
53
erg and
f
ν
< 0.15
(respectively,
E
tot,
ν
< 3.2 × 10^53 erg and
f
ν
< 0.88) for
E
-2
spectrum
and isotropic emission. Other assumptions including softer spectra and non-isotropic scenarios
have also been tested.
One of the main objectives of the ANTARES telescope is the search for point-like neutrino sources. Both the pointing accuracy and the angular resolution of the detector are important in this context ...and a reliable way to evaluate this performance is needed. In order to measure the pointing accuracy of the detector, one possibility is to study the shadow of the Moon, i.e. the deficit of the atmospheric muon flux from the direction of the Moon induced by the absorption of cosmic rays. Analysing the data taken between 2007 and 2016, the Moon shadow is observed with
3.5
σ
statistical significance. The detector angular resolution for downward-going muons is
0
.
73
∘
±
0
.
14
∘
.
The resulting pointing performance is consistent with the expectations. An independent check of the telescope pointing accuracy is realised with the data collected by a shower array detector onboard of a ship temporarily moving around the ANTARES location.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract
By constantly monitoring a very large portion of the sky, neutrino telescopes are well-designed to detect neutrinos emitted by transient astrophysical events. Real-time searches with the ...ANTARES telescope have been performed to look for neutrino candidates coincident with gamma-ray bursts detected by the
Swift
and
Fermi
satellites, high-energy neutrino events registered by IceCube, transient events from blazars monitored by HAWC, photon-neutrino coincidences by AMON notices and gravitational wave candidates observed by LIGO/Virgo. By requiring temporal coincidence, this approach increases the sensitivity and the significance of a potential discovery. This paper summarises the results of the follow-up performed of the ANTARES telescope between January 2014 and February 2022, which corresponds to the end of the data-taking period.
Abstract
Solar Atmospheric Neutrinos (SA
ν
s) are produced by the interaction of cosmic rays with the solar medium. The detection of SA
ν
s would provide useful information on the composition of ...primary cosmic rays as well as the solar density. These neutrinos represent an irreducible source of background for indirect searches for dark matter towards the Sun and the measurement of their flux would allow for a better assessment of the uncertainties related to these searches. In this paper we report on the analysis performed, based on an unbinned likelihood maximisation, to search for SA
ν
s with the ANTARES neutrino telescope. After analysing the data collected over 11 years, no evidence for a solar atmospheric neutrino signal has been found. An upper limit at 90% confidence level on the flux of solar atmospheric neutrinos has been obtained, equal to 7×10
-11
TeV
-1
cm
-2
s
-1
at E
ν
= 1 TeV for the reference cosmic ray model assumed.
Inside nuclear reactors, gamma-rays emitted from nuclei together with the neutrons introduce unwanted backgrounds in neutron spectra. For this reason, powerful extraction methods are needed to ...extract useful neutron signal from recorded mixture and thus to obtain clearer neutron flux spectrum. Actually, several techniques have been developed to discriminate between neutrons and gamma-rays in a mixed radiation field. Most of these techniques, tackle using analogue discrimination methods. Others propose to use some organic scintillators to achieve the discrimination task. Recently, systems based on digital signal processors are commercially available to replace the analog systems. As alternative to these systems, we aim in this work to verify the feasibility of using a Nonnegative Tensor Factorization (NTF) to blind extract neutron component from mixture signals recorded at the output of fission chamber (WL-7657). This last have been simulated through the Geant4 linked to Garfield++ using a 252Cf neutron source. To achieve our objective of obtaining the best possible neutron-gamma discrimination, we have applied the two different NTF algorithms, which have been found to be the best methods that allow us to analyse this kind of nuclear data.
Monte Carlo (MC) calculations used to require long CPU times, which made it prohibitive for routine clinical use. Several variance reduction techniques (VRTs) are included in the BEAMnrc MC code to ...significantly improve the efficiency of photon beams for which the computation time constitutes a problematic parameter. This work focused on the optimization of VRTs parameters to improve the efficiency by BEAMnrc code. This work deals with the use of different VRTs parameters alone or combined, such as directional bremsstrahlung splitting (DBS), uniform bremsstrahlung splitting (UBS), photon and electron splitting, Russian roulette (RR), range rejection, and bremsstrahlung cross section enhancement (BCSE) included in BEAMnrc code. We found that the relative improvement in efficiency due to UBS without RR, ICM_SPLIT (e-/e+), BCSE, and DBS is over 85, 130, 3489, and 4652 times higher in comparison to analog simulation for total photon fluence efficiency in 12 MV photon beam, respectively. VRTs combined in parallel simulation lead to enhance the dose efficiency by 19321 times compared to analog simulation. It is demonstrated that it is possible to further improve the efficiency by optimizing VRTs parameters combined and at the same time preserving its accuracy in parallel simulation of a 12 MV photon beam.
It is demonstrated that it is possible to further improve the efficiency by optimizing VRTs parameters combined and at the same time preserving its accuracy in parallel simulation of a 12 MV photon beam.
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