2,864 research outputs found

    The first version Buffered Large Analog Bandwidth (BLAB1) ASIC for high luminosity collider and extensive radio neutrino detectors

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    Future detectors for high luminosity particle identification and ultra high energy neutrino observation would benefit from a digitizer capable of recording sensor elements with high analog bandwidth and large record depth, in a cost-effective, compact and low-power way. A first version of the Buffered Large Analog Bandwidth (BLAB1) ASIC has been designed based upon the lessons learned from the development of the Large Analog Bandwidth Recorder and Digitizer with Ordered Readout (LABRADOR) ASIC. While this LABRADOR ASIC has been very successful and forms the basis of a generation of new, large-scale radio neutrino detectors, its limited sampling depth is a major drawback. A prototype has been designed and fabricated with 65k deep sampling at multi-GSa/s operation. We present test results and directions for future evolution of this sampling technique.Comment: 15 pages, 26 figures; revised, accepted for publication in NIM

    The CAST Time Projection Chamber

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    One of the three X-ray detectors of the CAST experiment searching for solar axions is a Time Projection Chamber (TPC) with a multi-wire proportional counter (MWPC) as a readout structure. Its design has been optimized to provide high sensitivity to the detection of the low intensity X-ray signal expected in the CAST experiment. A low hardware threshold of 0.8 keV is safely set during normal data taking periods, and the overall efficiency for the detection of photons coming from conversion of solar axions is 62 %. Shielding has been installed around the detector, lowering the background level to 4.10 x 10^-5 counts/cm^2/s/keV between 1 and 10 keV. During phase I of the CAST experiment the TPC has provided robust and stable operation, thus contributing with a competitive result to the overall CAST limit on axion-photon coupling and mass.Comment: 19 pages, 11 figures and images, submitted to New Journal of Physic

    The ArgoNeuT Detector in the NuMI Low-Energy beam line at Fermilab

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    The ArgoNeuT liquid argon time projection chamber has collected thousands of neutrino and antineutrino events during an extended run period in the NuMI beam-line at Fermilab. This paper focuses on the main aspects of the detector layout and related technical features, including the cryogenic equipment, time projection chamber, read-out electronics, and off-line data treatment. The detector commissioning phase, physics run, and first neutrino event displays are also reported. The characterization of the main working parameters of the detector during data-taking, the ionization electron drift velocity and lifetime in liquid argon, as obtained from through-going muon data complete the present report.Comment: 43 pages, 27 figures, 5 tables - update referenc

    A Highly Digital VCO-Based ADC With Lookup-Table-Based Background Calibration

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    CMOS technology scaling has enabled dramatic improvement for digital circuits both in terms of speed and power efficiency. However, most traditional analog-to-digital converter (ADC) architectures are challenged by ever-decreasing supply voltage. The improvement in time resolution enabled by increased digital speeds drives design towards time-domain architectures such as voltage-controlled-oscillator (VCO) based ADCs. The main challenge in VCO-based ADC design is mitigating the nonlinearity of VCO Voltage-to-frequency (V-to-f) characteristics. Achieving signal-to-noise ratio (SNR) performance better than 40dB requires some form of calibration, which can be realized by analog or digital techniques, or some combination. This dissertation proposes a highly digital, reconfigurable VCO-based ADC with lookup-table (LUT) based background calibration based on split ADC architecture. Each of the two split channels, ADC A and B , contains two VCOs in a differential configuration. This helps alleviate even-order distortions as well as increase the dynamic range. A digital controller on chip can reconfigure the ADCs\u27 sampling rates and resolutions to adapt to various application scenarios. Different types of input signals can be used to train the ADC’s LUT parameters through the simple, anti-aliasing continuous-time input to achieve target resolution. The chip is fabricated in a 180 nm CMOS process, and the active area of analog and digital circuits is 0.09 and 0.16mm^2, respectively. Power consumption of the core ADC function is 25 mW. Measured results for this prototype design with 12-b resolution show ENOB improves from uncorrected 5-b to 11.5-b with calibration time within 200 ms (780K conversions at 5 MSps sample rate)

    Advanced Denoising for X-ray Ptychography

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    The success of ptychographic imaging experiments strongly depends on achieving high signal-to-noise ratio. This is particularly important in nanoscale imaging experiments when diffraction signals are very weak and the experiments are accompanied by significant parasitic scattering (background), outliers or correlated noise sources. It is also critical when rare events such as cosmic rays, or bad frames caused by electronic glitches or shutter timing malfunction take place. In this paper, we propose a novel iterative algorithm with rigorous analysis that exploits the direct forward model for parasitic noise and sample smoothness to achieve a thorough characterization and removal of structured and random noise. We present a formal description of the proposed algorithm and prove its convergence under mild conditions. Numerical experiments from simulations and real data (both soft and hard X-ray beamlines) demonstrate that the proposed algorithms produce better results when compared to state-of-the-art methods.Comment: 24 pages, 9 figure

    The MEG detector for μ+e+γ{\mu}+\to e+{\gamma} decay search

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    The MEG (Mu to Electron Gamma) experiment has been running at the Paul Scherrer Institut (PSI), Switzerland since 2008 to search for the decay \meg\ by using one of the most intense continuous μ+\mu^+ beams in the world. This paper presents the MEG components: the positron spectrometer, including a thin target, a superconducting magnet, a set of drift chambers for measuring the muon decay vertex and the positron momentum, a timing counter for measuring the positron time, and a liquid xenon detector for measuring the photon energy, position and time. The trigger system, the read-out electronics and the data acquisition system are also presented in detail. The paper is completed with a description of the equipment and techniques developed for the calibration in time and energy and the simulation of the whole apparatus.Comment: 59 pages, 90 figure

    Bremsstrahlung Suppression due to the LPM and Dielectric Effects in a Variety of Materials

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    The cross section for bremsstrahlung from highly relativistic particles is suppressed due to interference caused by multiple scattering in dense media, and due to photon interactions with the electrons in all materials. We present here a detailed study of bremsstrahlung production of 200 keV to 500 MeV photons from 8 and 25 GeV electrons traversing a variety of target materials. For most targets, we observe the expected suppressions to a good accuracy. We observe that finite thickness effects are important for thin targets.Comment: 52 pages, 13 figures (incorporated in the revtex LaTeX file
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