1,207 research outputs found
In situ observation of atmospheric oxygen and carbon dioxide in the North Pacific using a cargo ship
Atmospheric oxygen (O2) and carbon dioxide (CO2) variations in the
North Pacific were measured aboard a cargo ship, the New Century 2
(NC2), while it cruised between Japan and the United States between
December 2015 and November 2016. A fuel cell analyzer and a nondispersive
infrared analyzer were used for the measurement of O2 and
CO2, respectively. To achieve parts-per-million precision for the
O2 measurements, we precisely controlled the flow rates of the
sample and reference air introduced into the analyzers and the outlet
pressure. A relatively low airflow rate (10 cm3 min−1) was
adopted to reduce the consumption rate of the reference gases. In the
laboratory, the system achieved measurement precisions of 3.8 per meg for
δ(O2 ∕ N2), which is commonly used to express
atmospheric O2 variation, and 0.1 ppm for the CO2 mole
fraction. After the in situ observation started aboard NC2, we found that
the ship's motion caused false wavy variations in the O2 signal
with an amplitude of more than several tens of ppm and a period of about
20 s. Although we have not resolved the problem at this stage, hourly
averaging considerably suppressed the variation associated with ship motion.
Comparison between the in situ observation and flask sampling of air
samples aboard NC2 showed that the averaged differences (in situ–flask)
and the standard deviations (±1σ) are −2.8 ± 9.4 per meg
for δ(O2 ∕ N2) and −0.02 ± 0.33 ppm
for the CO2 mole fraction. We compared 1 year of in situ data for
atmospheric potential oxygen (APO; O2 +1.1 × CO2)
obtained from the broad middle-latitude region
(140° E–130° W, 29° N–45° N) with
previous flask sampling data from the North Pacific. This comparison showed
that longitudinal differences in the seasonal amplitude of APO, ranging from
51 to 73 per meg, were smaller than the latitudinal differences.</p
Observation of Large CP Violation in the Neutral B Meson System
We present a measurement of the Standard Model CP violation parameter sin
2phi_1 based on a 29.1 fb^{-1} data sample collected at the Upsilon(4S)
resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider.
One neutral B meson is fully reconstructed as a J/psi Ks, psi(2S) Ks, chi_c1
Ks, eta_c Ks, J/psi K_L or J/psi K^{*0} decay and the flavor of the
accompanying B meson is identified from its decay products. From the asymmetry
in the distribution of the time intervals between the two B meson decay points,
we determine sin 2phi_1 = 0.99 +- 0.14(stat) +- 0.06(syst). We conclude that we
have observed CP violation in the neutral B meson system.Comment: 4 figures, to appear in Phys. Rev. Letter
Observation of chi_c2 Production in B-meson Decay
We report the first observation of chi_c2 production in B-meson decays. We
find an inclusive B -> chi_c2 X branching fraction of (1.80^{+0.23}_{-0.28}+/-
0.26) 10^-3. The data set, collected with the Belle detector at the KEKB e^+e^-
collider, consists of 31.9 million B\bar B events. We also present branching
fractions and momentum spectra for both chi_c1 and chi_c2 production.Comment: 5 pages with 2 figure
Measurement of the CP Violation Parameter sin(2phi_1) in B^0_d Meson Decays
We present a measurement of the Standard Model CP violation parameter
sin(2phi_1) based on a 10.5 fb^{-1} data sample collected at the Upsilon(4S)
resonance with the Belle detector at the KEKB asymmetric e+e- collider. One
neutral B meson is reconstructed in the J/psi K_S, psi(2S) K_S, chi_{c1} K_S,
eta_c K_S, J/psi K_L or J/psi pi^0 CP-eigenstate decay channel and the flavor
of the accompanying B meson is identified from its charged particle decay
products. From the asymmetry in the distribution of the time interval between
the two B-meson decay points, we determine sin(2phi_1) = 0.58 +0.32-0.34 (stat)
+0.09-0.10 (syst).Comment: LaTex, 13 pages, 3 figures, submitted to P.R.
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