45 research outputs found
First record of Gymnocranius griseus (Temminck & Schlegel, 1843) (family Lethrinidae) from southern Oman, Western Indian Ocean
Primer registre de Gymnocranius griseus (Temminck & Schlegel, 1843) (família Lethrinidae) del sud d’Oman, oest de l’oceà Índic
Es va recol·lectar un únic espècimen (285 mm longitud estàndard) de Gymnocranius griseus (Temminck & Schlegel, 1843) a la ciutat de Salalah (Oman), a la costa del mar d’Aràbia. És el primer registre d’aquesta espècie a les aigües d’Oman. Presenta característiques específiques: cos alt (2,17 vegades la longitud estàndard); els perfils dorsal i ventral del cap són uniformement convexos; el perfil de la part ventral del cos és recte; la vora inferior de l’ull se situa lleugerament per sota de la línia que uneix la part anterior de la boca amb el centre de l’aleta caudal lobulada; l’ull és relativament ample, de diàmetre pràcticament igual o lleugerament superior a les distàncies preorbitària i interorbitària; la boca és relativament petita i la part posterior dels maxil·lars arriba pràcticament al nivell dels orificis nasals anteriors; presenta tres parells de fines canines a la part anterior del maxil·lar superior i un parell a la part anterior de l’inferior, com també altres dents vil·liformes que adquireixen forma cònica a les parts laterals. L’espècimen va ser identificat com un G. griseus atès que les seves característiques corresponen a la descripció diagnòstica de Carpenter & Allen (1989).
Palabras clave: Gymnocranius griseus, Salalah, Mar de Arabia, Primer registro.A single specimen (285 mm SL) of Gymnocranius
griseus (Temminck & Schlegel, 1843) was collected from Salalah, Arabian Sea coast of Oman.
It is the first record of this species from the Omani waters. It shows specific characters:
deep body (2.17 times SL); evenly convex dorsal and ventral profile of head; ventral part
of body profile straight; lower edge of eye slightly above a line from tip of snout to middle
of caudal fin fork; eye relatively large, its diameter about equal to or slightly larger than
preorbital and interorbital widths; mouth relatively small, posterior part of jaws reaching to
about level of anterior nostrils; three pair and one pair of slender canines at front of upper
and lower jaw, respectively, other teeth villiform, becoming conical on lateral sections. The
specimen was identified as G. griseus as these characters fit the diagnostic description of
Carpenter & Allen (1989).
Key words: Gymnocranius griseus, Salalah, Arabian Sea, First record.Primer registre de Gymnocranius griseus (Temminck & Schlegel, 1843) (família Lethrinidae) del sud d’Oman, oest de l’oceà Índic
Es va recol·lectar un únic espècimen (285 mm longitud estàndard) de Gymnocranius griseus (Temminck & Schlegel, 1843) a la ciutat de Salalah (Oman), a la costa del mar d’Aràbia. És el primer registre d’aquesta espècie a les aigües d’Oman. Presenta característiques específiques: cos alt (2,17 vegades la longitud estàndard); els perfils dorsal i ventral del cap són uniformement convexos; el perfil de la part ventral del cos és recte; la vora inferior de l’ull se situa lleugerament per sota de la línia que uneix la part anterior de la boca amb el centre de l’aleta caudal lobulada; l’ull és relativament ample, de diàmetre pràcticament igual o lleugerament superior a les distàncies preorbitària i interorbitària; la boca és relativament petita i la part posterior dels maxil·lars arriba pràcticament al nivell dels orificis nasals anteriors; presenta tres parells de fines canines a la part anterior del maxil·lar superior i un parell a la part anterior de l’inferior, com també altres dents vil·liformes que adquireixen forma cònica a les parts laterals. L’espècimen va ser identificat com un G. griseus atès que les seves característiques corresponen a la descripció diagnòstica de Carpenter & Allen (1989).
Palabras clave: Gymnocranius griseus, Salalah, Mar de Arabia, Primer registro
Measurement of the Spectral Shape of the beta-decay of 137Xe to the Ground State of 137Cs in EXO-200 and Comparison with Theory
We report on a comparison between the theoretically predicted and
experimentally measured spectra of the first-forbidden non-unique -decay
transition ^{137}\textrm{Xe}(7/2^-)\to\,^{137}\textrm{Cs}(7/2^+). The
experimental data were acquired by the EXO-200 experiment during a deployment
of an AmBe neutron source. The ultra-low background environment of EXO-200,
together with dedicated source deployment and analysis procedures, allowed for
collection of a pure sample of the decays, with an estimated
signal-to-background ratio of more than 99-to-1 in the energy range from 1075
to 4175 keV. In addition to providing a rare and accurate measurement of the
first-forbidden non-unique -decay shape, this work constitutes a novel
test of the calculated electron spectral shapes in the context of the reactor
antineutrino anomaly and spectral bump.Comment: Version as accepted by PR
Generative Adversarial Networks for Scintillation Signal Simulation in EXO-200
Generative Adversarial Networks trained on samples of simulated or actual
events have been proposed as a way of generating large simulated datasets at a
reduced computational cost. In this work, a novel approach to perform the
simulation of photodetector signals from the time projection chamber of the
EXO-200 experiment is demonstrated. The method is based on a Wasserstein
Generative Adversarial Network - a deep learning technique allowing for
implicit non-parametric estimation of the population distribution for a given
set of objects. Our network is trained on real calibration data using raw
scintillation waveforms as input. We find that it is able to produce
high-quality simulated waveforms an order of magnitude faster than the
traditional simulation approach and, importantly, generalize from the training
sample and discern salient high-level features of the data. In particular, the
network correctly deduces position dependency of scintillation light response
in the detector and correctly recognizes dead photodetector channels. The
network output is then integrated into the EXO-200 analysis framework to show
that the standard EXO-200 reconstruction routine processes the simulated
waveforms to produce energy distributions comparable to that of real waveforms.
Finally, the remaining discrepancies and potential ways to improve the approach
further are highlighted.Comment: 20 pages, 10 figure
Measurement of the Spectral Shape of the β-Decay of ¹³⁷Xe to the Ground State of ¹³⁷Cs in EXO-200 and Comparison with Theory
We report on a comparison between the theoretically predicted and experimentally measured spectra of the first-forbidden nonunique β-decay transition ¹³⁷Xe(7/2⁻)→¹³⁷Cs(7/2⁺). The experimental data were acquired by the EXO-200 experiment during a deployment of an AmBe neutron source. The ultralow background environment of EXO-200, together with dedicated source deployment and analysis procedures, allowed for collection of a pure sample of the decays, with an estimated signal to background ratio of more than 99 to 1 in the energy range from 1075 to 4175 keV. In addition to providing a rare and accurate measurement of the first-forbidden nonunique β-decay shape, this work constitutes a novel test of the calculated electron spectral shapes in the context of the reactor antineutrino anomaly and spectral bump
An integrated online radioassay data storage and analytics tool for nEXO
Large-scale low-background detectors are increasingly used in rare-event
searches as experimental collaborations push for enhanced sensitivity. However,
building such detectors, in practice, creates an abundance of radioassay data
especially during the conceptual phase of an experiment when hundreds of
materials are screened for radiopurity. A tool is needed to manage and make use
of the radioassay screening data to quantitatively assess detector design
options. We have developed a Materials Database Application for the nEXO
experiment to serve this purpose. This paper describes this database, explains
how it functions, and discusses how it streamlines the design of the
experiment
Search for Two-neutrino Double-Beta Decay of to the excited state of with the Complete EXO-200 Dataset
A new search for two-neutrino double-beta () decay of
to the excited state of is performed with
the full EXO-200 dataset. A deep learning-based convolutional neural network is
used to discriminate signal from background events. Signal detection efficiency
is increased relative to previous searches by EXO-200 by more than a factor of
two. With the addition of the Phase II dataset taken with an upgraded detector,
the median 90 confidence level half-life sensitivity of
decay to the state of is
using a total exposure of . No statistically
significant evidence for decay to the state is
observed, leading to a lower limit of at 90 confidence level, a factor of
improvement over the current world's best constraint.Comment: 9 pages, 6 figures, 2 table
Measurement of the Spectral Shape of the β-Decay of ¹³⁷Xe to the Ground State of ¹³⁷Cs in EXO-200 and Comparison with Theory
We report on a comparison between the theoretically predicted and experimentally measured spectra of the first-forbidden nonunique β-decay transition ¹³⁷Xe(7/2⁻)→¹³⁷Cs(7/2⁺). The experimental data were acquired by the EXO-200 experiment during a deployment of an AmBe neutron source. The ultralow background environment of EXO-200, together with dedicated source deployment and analysis procedures, allowed for collection of a pure sample of the decays, with an estimated signal to background ratio of more than 99 to 1 in the energy range from 1075 to 4175 keV. In addition to providing a rare and accurate measurement of the first-forbidden nonunique β-decay shape, this work constitutes a novel test of the calculated electron spectral shapes in the context of the reactor antineutrino anomaly and spectral bump