63 research outputs found

    Narrow ridge waveguide high power single mode 1.3-μm InAs/InGaAs ten-layer quantum dot lasers

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    Ten-layer InAs/In0.15Ga0.85As quantum dot (QD) laser structures have been grown using molecular beam epitaxy (MBE) on GaAs (001) substrate. Using the pulsed anodic oxidation technique, narrow (2 μm) ridge waveguide (RWG) InAs QD lasers have been fabricated. Under continuous wave operation, the InAs QD laser (2 × 2,000 μm2) delivered total output power of up to 272.6 mW at 10 °C at 1.3 μm. Under pulsed operation, where the device heating is greatly minimized, the InAs QD laser (2 × 2,000 μm2) delivered extremely high output power (both facets) of up to 1.22 W at 20 °C, at high external differential quantum efficiency of 96%. Far field pattern measurement of the 2-μm RWG InAs QD lasers showed single lateral mode operation

    The performance of the jet trigger for the ATLAS detector during 2011 data taking

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    The performance of the jet trigger for the ATLAS detector at the LHC during the 2011 data taking period is described. During 2011 the LHC provided proton–proton collisions with a centre-of-mass energy of 7 TeV and heavy ion collisions with a 2.76 TeV per nucleon–nucleon collision energy. The ATLAS trigger is a three level system designed to reduce the rate of events from the 40 MHz nominal maximum bunch crossing rate to the approximate 400 Hz which can be written to offline storage. The ATLAS jet trigger is the primary means for the online selection of events containing jets. Events are accepted by the trigger if they contain one or more jets above some transverse energy threshold. During 2011 data taking the jet trigger was fully efficient for jets with transverse energy above 25 GeV for triggers seeded randomly at Level 1. For triggers which require a jet to be identified at each of the three trigger levels, full efficiency is reached for offline jets with transverse energy above 60 GeV. Jets reconstructed in the final trigger level and corresponding to offline jets with transverse energy greater than 60 GeV, are reconstructed with a resolution in transverse energy with respect to offline jets, of better than 4 % in the central region and better than 2.5 % in the forward direction

    Constraints on spin-0 dark matter mediators and invisible Higgs decays using ATLAS 13 TeV pp collision data with two top quarks and missing transverse momentum in the final state

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    This paper presents a statistical combination of searches targeting final states with two top quarks and invisible particles, characterised by the presence of zero, one or two leptons, at least one jet originating from a b-quark and missing transverse momentum. The analyses are searches for phenomena beyond the Standard Model consistent with the direct production of dark matter in pp collisions at the LHC, using 139 fb−1 of data collected with the ATLAS detector at a centre-of-mass energy of 13 TeV. The results are interpreted in terms of simplified dark matter models with a spin-0 scalar or pseudoscalar mediator particle. In addition, the results are interpreted in terms of upper limits on the Higgs boson invisible branching ratio, where the Higgs boson is produced according to the Standard Model in association with a pair of top quarks. For scalar (pseudoscalar) dark matter models, with all couplings set to unity, the statistical combination extends the mass range excluded by the best of the individual channels by 50 (25) GeV, excluding mediator masses up to 370 GeV. In addition, the statistical combination improves the expected coupling exclusion reach by 14% (24%), assuming a scalar (pseudoscalar) mediator mass of 10 GeV. An upper limit on the Higgs boson invisible branching ratio of 0.38 (0.30+0.13−0.09) is observed (expected) at 95% confidence level

    Search for long-lived neutral particles in pp collisions at s√=13 TeV that decay into displaced hadronic jets in the ATLAS calorimeter

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    This paper describes a search for pairs of neutral, long-lived particles decaying in the ATLAS calorimeter. Long-lived particles occur in many extensions to the Standard Model and may elude searches for new promptly decaying particles. The analysis considers neutral, long-lived scalars with masses between 5 and 400 GeV, produced from decays of heavy bosons with masses between 125 and 1000 GeV, where the long-lived scalars decay into Standard Model fermions. The analysis uses either 10.8 fb−1 or 33.0 fb−1 of data (depending on the trigger) recorded in 2016 at the LHC with the ATLAS detector in proton–proton collisions at a centre-of-mass energy of 13 TeV. No significant excess is observed, and limits are reported on the production cross section times branching ratio as a function of the proper decay length of the long-lived particles

    Deep generative models for fast photon shower simulation in ATLAS

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    The need for large-scale production of highly accurate simulated event samples for the extensive physics programme of the ATLAS experiment at the Large Hadron Collider motivates the development of new simulation techniques. Building on the recent success of deep learning algorithms, variational autoencoders and generative adversarial networks are investigated for modelling the response of the central region of the ATLAS electromagnetic calorimeter to photons of various energies. The properties of synthesised showers are compared with showers from a full detector simulation using geant4. Both variational autoencoders and generative adversarial networks are capable of quickly simulating electromagnetic showers with correct total energies and stochasticity, though the modelling of some shower shape distributions requires more refinement. This feasibility study demonstrates the potential of using such algorithms for ATLAS fast calorimeter simulation in the future and shows a possible way to complement current simulation techniques

    Search for doubly charged Higgs boson production in multi-lepton final states using 139 fb−1 of proton–proton collisions at s√ = 13 TeV with the ATLAS detector

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    A search for pair production of doubly charged Higgs bosons (H±± ), each decaying into a pair of prompt, isolated, and highly energetic leptons with the same electric charge, is presented. The search uses a proton–proton collision data sample at a centre-of-mass energy of 13 TeV corresponding to an integrated luminosity of 139 fb−1 recorded by the ATLAS detector during Run 2 of the Large Hadron Collider (LHC). This analysis focuses on same-charge leptonic decays, H±±→ℓ±ℓ′± where ℓ,ℓ′=e,μ,τ, in two-, three-, and four-lepton channels, but only considers final states which include electrons or muons. No evidence of a signal is observed. Corresponding upper limits on the production cross-section of a doubly charged Higgs boson are derived, as a function of its mass m(H±±), at 95% confidence level. Assuming that the branching ratios to each of the possible leptonic final states are equal, B(H±±→e±e±)=B(H±±→e±μ±)=B(H±±→μ±μ±)=B(H±±→e±τ±)=B(H±±→μ±τ±)=B(H±±→τ±τ±)=1/6, the observed (expected) lower limit on the mass of a doubly charged Higgs boson is 1080 GeV (1065 GeV) within the left-right symmetric type-II seesaw model, which is the strongest limit to date produced by the ATLAS Collaboration. Additionally, this paper provides the first direct test of the Zee–Babu neutrino mass model at the LHC, yielding an observed (expected) lower limit of m(H±±) = 900 GeV (880 GeV)

    НОВЫЕ МЕТОДЫ ЛЕЧЕНИЯ ВАСКУЛОГЕННОЙ ЭРЕКТИЛЬНОЙ ДИСФУНКЦИИ

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    Introduction. In the initial stages of vasculogenic erectile dysfunction (ED), young men who are dissatisfied by administration of inhibitor 5-phosphodiesterase and/or intracavernous injections tend to deny surgical treatment. At the decompensated stage of ED penile prosthesis implantation presents the method of choice. However, currently there are new treatment approaches, the effectiveness of which is actively being investigated.Materials and methods. In article results of surgical treatment of 38 patients (25–48 years, mean age 34.3 ± 7.4 years) with vasculogenic ED are presented: 33 – venoocclusive ED, 5 – arterial insufficiency of the corpora cavernosa, 2 of them have hemodynamic and clinical signs of arteriovenous ED in subcompensation. The treatment included stenting or endovascular embolization with spirals.Results. Maximum follow-up was 4 years. Overall clinical effectiveness and subsequent sexual rehabilitation were assessed as sufficient based on the international index of erectile function before surgery was 10,5 ± 3,6 (9–13) and after surgery – 21,3 ± 4,2 (14–25) (p = 0,001).Conclusion. Application of these innovative technologies allows to perform a sexual rehabilitation of most patients with ED and to avoid phalloprosthesis implantation.Введение. На начальных стадиях васкулогенной эректильной дисфункции (ЭД) артериовенозного генеза молодые мужчины, не удовлетворенные результатами терапии ингибиторами 5-фосфодиэстеразы и/или интракавернозными инъекциями, отвергают хирургическое лечение. На декомпенсированной стадии ЭД фаллопротезирование становится методом выбора. Однако существуют и новые методы лечения, эффективность которых активно исследуется.Материалы и методы. В статье приведены результаты хирургического лечения 38 пациентов 25–48 лет (в среднем 34,3 ± 7,4 года) с васкулогенной ЭД: 33 – с веноокклюзивными нарушениями эрекции, 5 – с артериальной недостаточностью кавернозных тел, из них у 2 были гемодинамические и клинические признаки артериовенозной ЭД в стадии субкомпенсации. Проводились стентирование или рентгеноэндоваскулярная эмболизация вен спиралями.Результаты. Максимальный срок наблюдения составил 4 года. Общая клиническая компенсация и последующая сексуальная реабилитация оценивалась как удовлетворительная: международный индекс эректильной функции до операции составил 10,5 ± 3,6 (9–13), после операции – 21,3 ± 4,2 (14–25) (p = 0,001).Заключение. Использование данных инновационных технологий позволяет провести сексуальную реабилитацию большинства больных с ЭД и избежать фаллопротезирования

    Sperm phenotypes in varicocele [Фенотип сперматозоидов при варикоцеле]

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    The study objective is to microscopically evaluate the morphology of sperm in patients with varicocele after surgical treatment and therapy with Prostatilen® AC. Materials and methods. The treatment group included 20 males between 26 and 45 years of age (mean age 31.6 ± 6.1 years) with various stages of varicocele and fertility problems; among them, 10 patients with subclinical stages of varicocele received conservative treatment with Prostatilen® AC (group 1) and were examined before and after the treatment; 10 males with infertility caused in part by varicocele of the spermatic cord veins were examined 6 months to 3 years after surgical treatment (group 2). Standard clinical and lab tests, sperm analysis, electron microscopy of the ejaculate were performed. The control group included 65 fertile males whose sperm samples were obtained from a bank of reproductive cells and tissues and used for comparison in microscopic examination. Results. In patients who received conservative treatment the number of sperm with immature chromatin decreased (p = 0.045) compared to the control group. This characteristic differed in patients after varicocelectomy and patients after conservative treatment (p = 0.037). Compared to control, the number of sperm with excess residual cytoplasm in the head and neck was higher in patients after varicocelectomy (p = 0.011). After conservative treatment, the number of sperm with excess residual cytoplasm was close to the control number and lower than in patients after varicocelectomy (р = 0.028). Conclusion. In patients with subclinical varicocele, conservative treatment with Prostatilen® AC leads to significant improvement in sperm ultrastructure compared to patients who underwent surgery to treat this pathology. © 2019 Andrologia i Genital'naa Hirurgia. All rights reserved
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