37 research outputs found
Measurement of the longitudinal diffusion of ionization electrons in the MicroBooNE detector
Abstract: Accurate knowledge of electron transport properties is vital to understanding the information provided by liquid argon time projection chambers (LArTPCs). Ionization electron drift-lifetime, local electric field distortions caused by positive ion accumulation, and electron diffusion can all significantly impact the measured signal waveforms. This paper presents a measurement of the effective longitudinal electron diffusion coefficient, DL, in MicroBooNE at the nominal electric field strength of 273.9 V/cm. Historically, this measurement has been made in LArTPC prototype detectors. This represents the first measurement in a large-scale (85 tonne active volume) LArTPC operating in a neutrino beam. This is the largest dataset ever used for this measurement. Using a sample of ∼70,000 through-going cosmic ray muon tracks tagged with MicroBooNE's cosmic ray tagger system, we measure DL = 3.74+0.28 -0.29 cm2/s
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High-speed electronic imaging applications at Los Alamos National Laboratory
An overview is presented of high-speed imaging technology developed at the Los Alamos National Laboratory. High-speed imaging is used by Los Alamos primarily in the underground testing of nuclear devices at the Nevada Test Site (NTS). The first camera system developed, which is still the work horse'' of this application, uses focus projection scan (FPS) vidicon imaging technology operating at an effective pixel readout rate of approximately 40 Mpixels/s. In an effort to take advantage of charge-coupled devices (CCD) technology, a CCD camera is under development that currently operates at approximately 25 Mpixels/s, but, with an improved CCD sensor, has the prospect of operating at 70-100 Mpixel/s. A possible application of the technology to the detection of military ordnance is discussed. Also, a flexible test station is described that has been assembled for testing CCDs at high pixel readout rates. The station can operate at clock rates of up to 100 MHz and can accommodate a wide variety of single and multiport sensors
HIV-1 Envelope Glycoproteins from Diverse Clades Differentiate Antibody Responses and Durability among Vaccinees.
Induction of broadly cross-reactive antiviral humoral responses with the capacity to target globally diverse circulating strains is a key goal for HIV-1 immunogen design. A major gap in the field is the identification of diverse HIV-1 envelope antigens to evaluate vaccine regimens for binding antibody breadth. In this study, we define unique antigen panels to map HIV-1 vaccine-elicited antibody breadth and durability. Diverse HIV-1 envelope glycoproteins were selected based on genetic and geographic diversity to cover the global epidemic, with a focus on sexually acquired transmitted/founder viruses with a tier 2 neutralization phenotype. Unique antigenicity was determined by nonredundancy (Spearman correlation), and antigens were clustered using partitioning around medoids (PAM) to identify antigen diversity. Cross-validation demonstrated that the PAM method was better than selection by reactivity and random selection. Analysis of vaccine-elicited V1V2 binding antibody in longitudinal samples from the RV144 clinical trial revealed the striking heterogeneity among individual vaccinees in maintaining durable responses. These data support the idea that a major goal for vaccine development is to improve antibody levels, breadth, and durability at the population level. Elucidating the level and durability of vaccine-elicited binding antibody breadth needed for protection is critical for the development of a globally efficacious HIV vaccine. <b>IMPORTANCE</b> The path toward an efficacious HIV-1 vaccine will require characterization of vaccine-induced immunity that can recognize and target the highly genetically diverse virus envelope glycoproteins. Antibodies that target the envelope glycoproteins, including diverse sequences within the first and second hypervariable regions (V1V2) of gp120, were identified as correlates of risk for the one partially efficacious HIV-1 vaccine. To build upon this discovery, we experimentally and computationally evaluated humoral responses to define envelope glycoproteins representative of the antigenic diversity of HIV globally. These diverse envelope antigens distinguished binding antibody breadth and durability among vaccine candidates, thus providing insights for advancing the most promising HIV-1 vaccine candidates
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High-speed TV cameras for streak tube readout
Two fast framing TV cameras have been characterized and compared as readout media for imaging of 40 mm diameter streak tube (P-11) phosphor screens. One camera is based upon a Focus-Projection-Scan (FPS) high-speed electrostatic deflected vidicon with 30-mm-diameter PbO target. The other uses an interline transfer charge-coupled device (CCD) with 8.8 {times} 11.4 mm rectangular Si target. The field-of-view (FOV), resolution, responsivity, and dynamic range provided by both cameras when exposed to short duration ({approx} 10 {mu} full width at half maximum (FWHM)) transient illumination followed by a single field readout period of {lt}3 ms are presented. 11 refs., 8 figs., 3 tabs
EpiNet study of incidence of status epilepticus in Auckland, New Zealand: Methods and preliminary results.
The EpiNet project has been commenced to facilitate investigator-led collaborative research in epilepsy. A new Web-based data collection tool has been developed within EpiNet to record comprehensive data regarding status epilepticus and has been used for a study of status epilepticus in Auckland, New Zealand. All patients aged >4 weeks who presented to any of the five public hospitals and the major private hospital within Auckland city (population = 1.61 million) with an episode of status epilepticus between April 6, 2015 and April 5, 2016 were identified using multiple overlapping sources of information. For this study, status epilepticus was defined as any seizure exceeding 10 minutes in duration, or repeated seizures lasting >10 minutes without recovery between seizures. Patients who had either convulsive or nonconvulsive status epilepticus were included. Episodes of status epilepticus were classified according to the 2015 International League Against Epilepsy ILAE status epilepticus classification. A total of 477 episodes in 367 patients were considered as definite or probable status epilepticus; 285 episodes (62%) lasted >30 minutes, which is the duration that has previously been used for epidemiological studies of status epilepticus
DESHIMA 2.0: Development of an Integrated Superconducting Spectrometer for Science-Grade Astronomical Observations
Integrated superconducting spectrometer (ISS) technology will enable ultra-wideband, integral-field spectroscopy for (sub)millimeter-wave astronomy, in particular, for uncovering the dust-obscured cosmic star formation and galaxy evolution over cosmic time. Here, we present the development of DESHIMA 2.0, an ISS for ultra-wideband spectroscopy toward high-redshift galaxies. DESHIMA 2.0 is designed to observe the 220–440 GHz band in a single shot, corresponding to a redshift range of z = 3.3–7.6 for the ionized carbon emission ([C II] 158 μ m). The first-light experiment of DESHIMA 1.0, using the 332–377 GHz band, has shown an excellent agreement among the on-sky measurements, the laboratory measurements, and the design. As a successor to DESHIMA 1.0, we plan the commissioning and the scientific observation campaign of DESHIMA 2.0 on the ASTE 10-m telescope in 2023. Ongoing upgrades for the full octave-bandwidth system include the wideband 347-channel chip design and the wideband quasi-optical system. For efficient measurements, we also develop the observation strategy using the mechanical fast sky-position chopper and the sky-noise removal technique based on a novel data-scientific approach. In the paper, we show the recent status of the upgrades and the plans for the scientific observation campaign.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Tera-Hertz SensingElectronic