1,115 research outputs found

    The Weak Tie Between Natural Gas and Oil Prices

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    Several recent studies establish that crude oil and natural gas prices are cointegrated, so that changes in the price of oil appear to translate into changes in the price of natural gas. Yet at times in the past, and very powerfully in the last two years, many voices have noted that the two prices series appear to have "decoupled". We explore the apparent contradiction between these two views. Although we also find that the two series are cointegrated, recognition of the statistical fact of cointegration needs to be tempered with two additional points that we think have been insufficiently emphasized in the past literature. First, there is an enormous amount of unexplained volatility in natural gas prices at short horizons. Hence, any simple formulaic relationship between the price of oil and the price of natural gas will leave a large portion of the price of natural gas unexplained. Second, the cointegrating relationship does not appear to be stable through time. Natural gas prices may be tied to oil prices, but the relationship can shift dramatically over time. Therefore, although the two price series are cointegrated, the confidence intervals for both short and long time horizons are large.Massachusetts Institute of Technology. Center for Energy and Environmental Policy Researc

    Kaon decay interferometry as meson dynamics probes

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    We discuss the time dependent interferences between KLK_L and KSK_S in the decays in 3π3\pi and ππγ\pi\pi\gamma, to be studied at interferometry machines such as the ϕ\phi-factory and LEAR. We emphasize the possibilities and the advantages of using interferences, in comparison with width measurements, to obtain information both on CPCP conserving and CPCP violating amplitudes. Comparison with present data and suggestions for future experiments are made.Comment: 15 pages, in RevTex, Report INFNNA-IV-93-31, UTS-DFT-93-2

    Quartz Cherenkov Counters for Fast Timing: QUARTIC

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    We have developed particle detectors based on fused silica (quartz) Cherenkov radiators read out with micro-channel plate photomultipliers (MCP-PMTs) or silicon photomultipliers (SiPMs) for high precision timing (Sigma(t) about 10-15 ps). One application is to measure the times of small angle protons from exclusive reactions, e.g. p + p - p + H + p, at the Large Hadron Collider, LHC. They may also be used to measure directional particle fluxes close to external or stored beams. The detectors have small areas (square cm), but need to be active very close (a few mm) to the intense LHC beam, and so must be radiation hard and nearly edgeless. We present results of tests of detectors with quartz bars inclined at the Cherenkov angle, and with bars in the form of an "L" (with a 90 degree corner). We also describe a possible design for a fast timing hodoscope with elements of a few square mm.Comment: 24 pages, 14 figure

    Measurements of the Decay KLe+eγK_L \to e^+e^-\gamma

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    The E799-II (KTeV) experiment at Fermilab has collected 83262 KLe+eγK_L \to e^+e^-\gamma events above a background of 79 events. We measure a decay width, normalized to the KLπ0π0πD0K_L \to \pi^0\pi^0\pi^0_D (\pi^0 \to \gamma\gamma, \pi^0 to \gamma\gamma, \pi^0_D \to e^+e^-\gamma) decay width, of Γ(\Gamma(K_L \to e^+e^-\gamma)/Γ(KLπ0π0πD0)=(1.3302±0.0046stat±0.0102syst)×103)/\Gamma(K_L \to \pi^0\pi^0\pi^0_D) = (1.3302 \pm 0.0046_{stat} \pm 0.0102_{syst}) \times 10^{-3}. We also measure parameters of two KLγγK_L \gamma^{\ast}\gamma form factor models. In the Bergstrom, Masso, and Singer (BMS) parametrization, we find \caks = -0.517 \pm 0.030_{stat} \pm 0.022_{syst}. We separately fit for the first parameter of the D'Ambrosio, Isidori, and Portoles (DIP) model and find \adip = -1.729 \pm 0.043_{stat} \pm 0.028_{syst}.Comment: 5 pages, 3 figures, submitted to PR

    Improved KL->pi e nu Form Factor and Phase Space Integral with Reduced Model Uncertainty

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    Using the published KTeV sample of 2 million KL-> pi e nu decays and a new form factor expansion with a rigorous bound on higher order terms, we present a new determination of the KL->pi e nu form factor and phase space integral. Compared to the previous KTeV result, the uncertainty in the new form factor expansion is negligible and results in an overall uncertainty in the phase space integral (IKe) that is a factor of two smaller: IKe = 0.15392 +- 0.00048 \.Comment: 3 pages, 2 figures, submitted to PRD Rapid Communicatio

    Search for the Rare Decay K_{L}\to\pi^{0}\pi^{0}\gamma

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    The KTeV E799 experiment has conducted a search for the rare decay KLπ0π0γK_{L}\to\pi^{0}\pi^{0}\gamma via the topology KLπ0πD0γK_{L}\to\pi^{0}\pi^{0}_D\gamma (where πD0γe+e\pi^0_D\to\gamma e^+e^-). Due to Bose statistics of the π0\pi^0 pair and the real nature of the photon, the KLπ0π0γK_{L}\to\pi^{0}\pi^{0}\gamma decay is restricted to proceed at lowest order by the CP conserving direct emission (DE) of an E2 electric quadrupole photon. The rate of this decay is interesting theoretically since chiral perturbation theory predicts that this process vanishes at level O(p4)O(p^4). Therefore, this mode probes chiral perturbation theory at O(p6)O(p^6). In this paper we report a determination of an upper limit of 2.43×1072.43\times 10^{-7} (90% CL) for KLπ0π0γK_{L}\to\pi^{0}\pi^{0}\gamma. This is approximately a factor of 20 lower than previous results.Comment: six pages and six figures in the submission. Reformatted for Physics Review

    New Fast Shower Max Detector Based on MCP as an Active Element

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    One possibility to make a fast and radiation resistant shower maximum (SM) detector is to use a secondary emitter as an active element. We present below test beam results, obtained with different types of photo detectors based on micro channel plates (MCP) as secondary emitter. The SM time resolution – we obtained for this new type of detector is at the level of 20-30 ps. We estimate that a significant contribution to the detector response originates from secondary emission of the MCP

    Detailed Study of the KL -> 3pi0 Dalitz Plot

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    Using a sample of 68 million KL -> 3pi0 decays collected in 1996-1999 by the KTeV (E832) experiment at Fermilab, we present a detailed study of the KL -> 3pi0 Dalitz plot density. We report the first observation of interference from KL->pi+pi-pi0 decays in which pi+pi- rescatters to 2pi0 in a final-state interaction. This rescattering effect is described by the Cabibbo-Isidori model, and it depends on the difference in pion scattering lengths between the isospin I=0 and I=2 states, a0-a2. Using the Cabibbo-Isidori model, we present the first measurement of the KL-> 3pi0 quadratic slope parameter that accounts for the rescattering effect.Comment: accepted by Phys. Rev

    Expression of Interest: The Atmospheric Neutrino Neutron Interaction Experiment (ANNIE)

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    Submitted for the January 2014 Fermilab Physics Advisory Committee meetingSubmitted for the January 2014 Fermilab Physics Advisory Committee meetingSubmitted for the January 2014 Fermilab Physics Advisory Committee meetingSubmitted for the January 2014 Fermilab Physics Advisory Committee meetingNeutron tagging in Gadolinium-doped water may play a significant role in reducing backgrounds from atmospheric neutrinos in next generation proton-decay searches using megaton-scale Water Cherenkov detectors. Similar techniques might also be useful in the detection of supernova neutrinos. Accurate determination of neutron tagging efficiencies will require a detailed understanding of the number of neutrons produced by neutrino interactions in water as a function of momentum transferred. We propose the Atmospheric Neutrino Neutron Interaction Experiment (ANNIE), designed to measure the neutron yield of atmospheric neutrino interactions in gadolinium-doped water. An innovative aspect of the ANNIE design is the use of precision timing to localize interaction vertices in the small fiducial volume of the detector. We propose to achieve this by using early production of LAPPDs (Large Area Picosecond Photodetectors). This experiment will be a first application of these devices demonstrating their feasibility for Water Cherenkov neutrino detectors
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