In the pedunculate barnacle Alepas pacifica Pilsbry, 1907, a symbiont of jellyfish, several small individuals were found attached to conspecifics rather than directly to the host. We investigated ...whether these individuals act as dwarf males, as is known in some other species of barnacles. The conspecific-attached individuals had longer penes than juvenile hermaphrodites of similar sizes attached directly to the jellyfish, although there was no other morphological difference between these two types of individuals. Only the largest conspecific-attached individual was ovigerous. We conclude that the conspecific-attached individuals are dwarf males, which develop the male function at a smaller size than hermaphrodites do, with a small possibility of becoming hermaphroditic. This is the first report of dwarf males, and hence of the coexistence of males and hermaphrodites (androdioecy), in the family Lepadidae. In addition, the record of A. pacifica attached to Nemopilema nomurai Kishinouye, 1922, is reported herein as new to science. Chez la bernacle pédonculée Alepas pacifica Pilsbry, 1907, symbionte de méduse, plusieurs petits individus ont été trouvés attachés à des congénères plutôt que directement sur l’hôte. Nous avons recherché si ces individus agissent comme des mâles nains, comme c’est connu chez d'autres espèces de bernacles. Les individus attachés aux congénères ont des pénis plus longs que les juvéniles hermaphrodites de taille similaire attachés directement à la méduse, bien qu'il n'y avait pas d'autre différence morphologique entre les deux types d'individus. Seul le plus gros individu attaché à des congénères était ovigère. Nous concluons que les individus attachés à des congénères sont des mâles nains, qui développent la fonction mâle à une taille plus petite que ce que font les hermaphrodites, avec une faible possibilité de devenir hermaphrodites. Ceci est le premier signalement de mâles nains, et par conséquent la coexistence de mâles et d'hermaphrodites (androdioécie), dans la famille des Lepadidae. De plus le signalement de l'attachement de A. pacifica à Nemopilema nomurai Kishinouye, 1922, rapporté ici est aussi une nouveauté.
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Development of slow control system for the Belle II ARICH counter Yonenaga, M.; Adachi, I.; Dolenec, R. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2017, Letnik:
876
Journal Article
Recenzirano
A slow control system (SCS) for the Aerogel Ring Imaging Cherenkov (ARICH) counter in the Belle II experiment was newly developed and coded in the development frameworks of the Belle II DAQ software. ...The ARICH is based on 420 Hybrid Avalanche Photo-Detectors (HAPDs). Each HAPD has 144 pixels to be readout and requires 6 power supply (PS) channels, therefore a total number of 2520 PS channels and 60,480 pixels have to be configured and controlled. Graphical User Interfaces (GUIs) with detector oriented view and device oriented view, were also implemented to ease the detector operation. The ARICH SCS is in operation for detector construction and cosmic rays tests. The paper describes the detailed features of the SCS and preliminary results of operation of a reduced set of hardware which confirm the scalability to the full detector.
Development of the ARICH monitor system for the Belle II experiment Hataya, K.; Adachi, I.; Dolenec, R. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2017, Letnik:
876
Journal Article
Recenzirano
The Belle II detector is under construction at KEK in Japan. In the forward endcap region of the Belle II detector, particle identification (PID) is performed by the Aerogel Ring Imaging Cherenkov ...(ARICH) counter composed of aerogel tiles and 144-channel Hybrid Avalanche Photo-Detectors (HAPDs). The photon detection efficiency of the photosensor is important for a stable operation of the ARICH. To examine the performance of the HAPDs periodically, a monitor system using scattered photons injected by optical fibers is being developed. In this paper, we report the test using the prototype monitor system and the tests with a partially built ARICH detector.
Abstract
The Aerogel Ring Imaging Cherenkov (ARICH) counter serves as a particle identification device in the forward end-cap region of the Belle II spectrometer. It is capable of identifying pions ...and kaons with momenta up to $4\>$GeV$\>$c$^{-1}$ by detecting Cherenkov photons emitted in the silica aerogel radiator. After the detector alignment and calibration of the probability density function, we evaluate the performance of the ARICH counter using early beam collision data. Event samples of $D^{\ast +} \to D^0 \pi^+ (D^0 \to K^-\pi^+)$ were used to determine the $\pi(K)$ efficiency and the $K(\pi)$ misidentification probability. We found that the ARICH counter is capable of separating kaons from pions with an identification efficiency of $93.5 \pm 0.6 \, \%$ at a pion misidentification probability of $10.9 \pm 0.9 \, \%$. This paper describes the identification method of the counter and the evaluation of the performance during its early operation.
A 144-channel HAPD for the Aerogel RICH at Belle II Korpar, S.; Adachi, I.; Hamada, N. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2014, Letnik:
766
Journal Article
Recenzirano
A hybrid photo-detector (HAPD) has been developed for the aerogel RICH (ARICH) of the Belle II experiment. In the present contribution we report the performance tests in magnetic fields, results of ...the neutron and gamma irradiation studies, and of aging tests. We also review the production status and plans.
In the Belle II experiment, an aerogel-based proximity focusing ring-imaging Cherenkov (ARICH) counter is used for charged particle identification (PID) in the forward end-cap region. The goal is to ...separate kaons from pions at above 4σ significance level for momenta up to 4 GeV/c, which is critical for the measurements of rare B decays and CP violation in B decays. Chrerenkov photons are emitted in aerogel tiles and 144-channel Hybrid Avalanche Photo Detector (HAPDs) are used as the photo-detectors. We utilize a two-layer aerogel design with different refractive indexes in a focusing configuration. In Phase 3 of the Belle II operation (from Apr. 2019), the ARICH system has been operating smoothly. The performance of particle identification with ARICH has been well validated and is in agreement with simulation.
We search for bottomonium states in Υ(2S) → (bb)γ decays with an integrated luminosity of 24.7 fb(-1) recorded at the Υ(2S) resonance with the Belle detector at KEK, containing (157.8±3.6)×10(6) ...Υ(2S) events. The (bb) system is reconstructed in 26 exclusive hadronic final states composed of charged pions, kaons, protons, and K(S)(0) mesons. We find no evidence for the state recently observed around 9975 MeV (X(bb)) in an analysis based on a data sample of 9.3×10(6) Υ(2S) events collected with the CLEO III detector. We set a 90% confidence level upper limit on the branching fraction BΥ(2S) → X(bb)γ × ∑(i)BX(bb) → h(i) < 4.9×10(-6), summed over the exclusive hadronic final states employed in our analysis. This result is an order of magnitude smaller than the measurement reported with CLEO data. We also set an upper limit for the ηb(1S) state of BΥ(2S) → ηb(1S)γ × ∑(i)Bηb(1S) → h(i) < 3.7×10(-6).
Muon identification in the Belle experiment at KEKB Abashian, A; Abe, K; Abe, K ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/2002, Letnik:
491, Številka:
1-2
Journal Article
Recenzirano
Odprti dostop
This paper describes the muon identification method and its performance in the Belle experiment at KEKB. Muon and hadron likelihood are calculated for each track using its range and transverse ...scattering in the KL-and-muon detector (KLM). We apply a cut on the normalized muon likelihood Lμ to identify the track as a muon. Above the detection threshold of 0.6GeV/c, the measured muon detection efficiency and pion fake rate are approximately constant for momenta greater than 1.0 and 1.5GeV/c, respectively. Between 1.0 and 3.0GeV/c, the averaged muon detection efficiency is 89% and the pion fake rate per track is 1.4% over the KLM acceptance, using the standard selection criterion Lμ>0.9.
We have developed a new type of particle identification device, called an aerogel ring imaging Cherenkov (ARICH) counter, for the Belle II experiment. It uses silica aerogel tiles as Cherenkov ...radiators. For detection of Cherenkov photons, hybrid avalanche photo-detectors (HAPDs) are used. The designed HAPD has a high sensitivity to single photons under a strong magnetic field. We have confirmed that the HAPD provides high efficiency for single-photon detection even after exposure to neutron and
$\gamma $
-ray radiation that exceeds the levels expected in the 10-year Belle II operation. In order to confirm the basic performance of the ARICH counter system, we carried out a beam test at the using a prototype of the ARICH counter with six HAPD modules. The results are in agreement with our expectations and confirm the suitability of the ARICH counter for the Belle II experiment. Based on the in-beam performance of the device, we expect that the identification efficiency at
$3.5\,{\rm GeV}/c$
is 97.4% and 4.9% for pions and kaons, respectively. This paper summarizes the development of the HAPD for the ARICH and the evaluation of the performance of the prototype ARICH counter built with the final design components.
The mode of inheritance of body colour polymorphism (yellow or brown) was studied in the apple snail Pomacea canaliculata. Analyses of snail body colour over three generations showed that the yellow ...colour follows simple Mendelian inheritance, being recessive to brown. There were no deleterious effects of the yellow colour gene on the number of eggs per egg mass, egg weight, hatchability, daily egg mass production, or survival of the snails carrying it. By using the yellow colour as a genetic marker, the pattern of sperm competition was investigated. When two males (yellow and brown) were mated successively to a yellow female, sperm of the first male were displaced by the second male in all 10 cases studied. However, the duration needed for complete displacement varied among females, from just after the male exchange (within 4 days) up to 38 days. Yellow males had a comparable reproductive success to that of brown males.
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