478,018 research outputs found
Muon and Cosmogenic Neutron Detection in Borexino
Borexino, a liquid scintillator detector at LNGS, is designed for the
detection of neutrinos and antineutrinos from the Sun, supernovae, nuclear
reactors, and the Earth. The feeble nature of these signals requires a strong
suppression of backgrounds below a few MeV. Very low intrinsic radiogenic
contamination of all detector components needs to be accompanied by the
efficient identification of muons and of muon-induced backgrounds. Muons
produce unstable nuclei by spallation processes along their trajectory through
the detector whose decays can mimic the expected signals; for isotopes with
half-lives longer than a few seconds, the dead time induced by a muon-related
veto becomes unacceptably long, unless its application can be restricted to a
sub-volume along the muon track. Consequently, not only the identification of
muons with very high efficiency but also a precise reconstruction of their
tracks is of primary importance for the physics program of the experiment. The
Borexino inner detector is surrounded by an outer water-Cherenkov detector that
plays a fundamental role in accomplishing this task. The detector design
principles and their implementation are described. The strategies adopted to
identify muons are reviewed and their efficiency is evaluated. The overall muon
veto efficiency is found to be 99.992% or better. Ad-hoc track reconstruction
algorithms developed are presented. Their performance is tested against muon
events of known direction such as those from the CNGS neutrino beam, test
tracks available from a dedicated External Muon Tracker and cosmic muons whose
angular distribution reflects the local overburden profile. The achieved
angular resolution is 3-5 deg and the lateral resolution is 35-50 cm, depending
on the impact parameter of the crossing muon. The methods implemented to
efficiently tag cosmogenic neutrons are also presented.Comment: 42 pages. 32 figures on 37 files. Uses JINST.cls. 1 auxiliary file
(defines.tex) with TEX macros. submitted to Journal of Instrumentatio
Muon and Cosmogenic Neutron Detection in Borexino
Borexino, a liquid scintillator detector at LNGS, is designed for the
detection of neutrinos and antineutrinos from the Sun, supernovae, nuclear
reactors, and the Earth. The feeble nature of these signals requires a strong
suppression of backgrounds below a few MeV. Very low intrinsic radiogenic
contamination of all detector components needs to be accompanied by the
efficient identification of muons and of muon-induced backgrounds. Muons
produce unstable nuclei by spallation processes along their trajectory through
the detector whose decays can mimic the expected signals; for isotopes with
half-lives longer than a few seconds, the dead time induced by a muon-related
veto becomes unacceptably long, unless its application can be restricted to a
sub-volume along the muon track. Consequently, not only the identification of
muons with very high efficiency but also a precise reconstruction of their
tracks is of primary importance for the physics program of the experiment. The
Borexino inner detector is surrounded by an outer water-Cherenkov detector that
plays a fundamental role in accomplishing this task. The detector design
principles and their implementation are described. The strategies adopted to
identify muons are reviewed and their efficiency is evaluated. The overall muon
veto efficiency is found to be 99.992% or better. Ad-hoc track reconstruction
algorithms developed are presented. Their performance is tested against muon
events of known direction such as those from the CNGS neutrino beam, test
tracks available from a dedicated External Muon Tracker and cosmic muons whose
angular distribution reflects the local overburden profile. The achieved
angular resolution is 3-5 deg and the lateral resolution is 35-50 cm, depending
on the impact parameter of the crossing muon. The methods implemented to
efficiently tag cosmogenic neutrons are also presented.Comment: 42 pages. 32 figures on 37 files. Uses JINST.cls. 1 auxiliary file
(defines.tex) with TEX macros. submitted to Journal of Instrumentatio
Muon and Cosmogenic Neutron Detection in Borexino
Borexino, a liquid scintillator detector at LNGS, is designed for the
detection of neutrinos and antineutrinos from the Sun, supernovae, nuclear
reactors, and the Earth. The feeble nature of these signals requires a strong
suppression of backgrounds below a few MeV. Very low intrinsic radiogenic
contamination of all detector components needs to be accompanied by the
efficient identification of muons and of muon-induced backgrounds. Muons
produce unstable nuclei by spallation processes along their trajectory through
the detector whose decays can mimic the expected signals; for isotopes with
half-lives longer than a few seconds, the dead time induced by a muon-related
veto becomes unacceptably long, unless its application can be restricted to a
sub-volume along the muon track. Consequently, not only the identification of
muons with very high efficiency but also a precise reconstruction of their
tracks is of primary importance for the physics program of the experiment. The
Borexino inner detector is surrounded by an outer water-Cherenkov detector that
plays a fundamental role in accomplishing this task. The detector design
principles and their implementation are described. The strategies adopted to
identify muons are reviewed and their efficiency is evaluated. The overall muon
veto efficiency is found to be 99.992% or better. Ad-hoc track reconstruction
algorithms developed are presented. Their performance is tested against muon
events of known direction such as those from the CNGS neutrino beam, test
tracks available from a dedicated External Muon Tracker and cosmic muons whose
angular distribution reflects the local overburden profile. The achieved
angular resolution is 3-5 deg and the lateral resolution is 35-50 cm, depending
on the impact parameter of the crossing muon. The methods implemented to
efficiently tag cosmogenic neutrons are also presented.Comment: 42 pages. 32 figures on 37 files. Uses JINST.cls. 1 auxiliary file
(defines.tex) with TEX macros. submitted to Journal of Instrumentatio
Multiangle social network recommendation algorithms and similarity network evaluation
Multiangle social network recommendation algorithms (MSN) and a new assessmentmethod, called similarity network evaluation (SNE), are both proposed. From the viewpoint of six dimensions, the MSN are classified into six algorithms, including user-based algorithmfromresource point (UBR), user-based algorithmfromtag point (UBT), resource-based algorithm fromtag point (RBT), resource-based algorithm from user point (RBU), tag-based algorithm from resource point (TBR), and tag-based algorithm from user point (TBU). Compared with the traditional recall/precision (RP) method, the SNE is more simple, effective, and visualized. The simulation results show that TBR and UBR are the best algorithms, RBU and TBU are the worst ones, and UBT and RBT are in the medium levels
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RGFGA: An efficient representation and crossover for grouping genetic algorithms
There is substantial research into genetic algorithms that are used to group large numbers of
objects into mutually exclusive subsets based upon some fitness function. However, nearly all
methods involve degeneracy to some degree.
We introduce a new representation for grouping genetic algorithms, the restricted growth function
genetic algorithm, that effectively removes all degeneracy, resulting in a more efficient search. A new crossover operator is also described that exploits a measure of similarity between chromosomes in a population. Using several synthetic datasets, we compare the performance of our representation and crossover with another well known state-of-the-art GA method, a strawman
optimisation method and a well-established statistical clustering algorithm, with encouraging results
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