3,074 research outputs found
Interview with Peter John Wyllie
No full textAn interview in four sessions, March and April 2002, with Peter John Wyllie, professor of geology, emeritus, in the Division of Geological and Planetary Sciences. Dr. Wyllie received his undergraduate and graduate education at the University of St Andrews, in Scotland (BSc, geology and physics, 1952; BSc, geology, 1955, honors; PhD 1958). Joined Caltech faculty 1983 as chair of the Division of Geological and Planetary Sciences, remaining chairman until 1987. Served as divisional academic officer 1994-1999 and became professor emeritus in 1999.
In this interview, he recalls growing up in England, his grammar school education, national service, undergraduate career at St Andrews, and participation in two British Greenland Expeditions (1950 and 1952-1954). Graduate work with Harald Drever at St Andrews, continuing under O. F. Tuttle at Penn State. Postdoc at Leeds University, U.K., 1959-1961. Returned to Penn State in 1961 as associate professor of geochemistry. Moved to the University of Chicago in 1965, remaining for eighteen years and chairing the Department of Geophysical Sciences before coming to Caltech.
He discusses his division chairmanship, teaching the introductory geology course, and the evolution of the division’s curriculum, particularly under chairman Edward M. Stolper. Recalls his involvement with various geological societies and receipt of several awards, including Wollaston Medal (1982) and Roebling Medal, Mineralogical Society of America (2001). Discusses his work on the National Academy of Sciences’ first national survey of earth sciences. Discusses high-pressure experimental petrology at Penn State, Chicago, and Caltech with various graduate students and postdocs, including Gus Koster van Groos, David Watkinson, John K. Robertson, Wuu-Liang Huang, and Who-jer Lee. Comments on the current state of the division as it moves into an era of global change and collaboration with environmental engineering
Where's the petrology in "Earth Sciences and Society"
No full text"The first, by Peter Wyllie, is entitled ‘Where's the Petrology in Earth Sciences and Society’, and reviews the involvement of igneous and metamorphic petrology in the Whole Earth system approach advocated in the first US national disciplinary survey of Earth Sciences, Solid-Earth Sciences and Society, published by the US National Academy of Sciences Press in 1993.
Measurement of the ratio of branching fractions B(B0→K∗0γ )/B(B0s→φγ ) and the directCP asymmetry inB 0→K∗0γ
No full textThe ratio of branching fractions of the radiative B decays B0→K⁎0γ and B0s→ϕγ has been measured using an integrated luminosity of 1.0 fb−1 of pp collision data collected by the LHCb experiment at a centre-of-mass energy of s√=7TeV. The value obtained is
B(B0→K⁎0γ)B(B0s→ϕγ)=1.23±0.06(stat.)±0.04(syst.)±0.10(fs/fd),
where the first uncertainty is statistical, the second is the experimental systematic uncertainty and the third is associated with the ratio of fragmentation fractions fs/fd. Using the world average value for B(B0→K⁎0γ), the branching fraction B(B0s→ϕγ) is measured to be (3.5±0.4)×10−5.
The direct CP asymmetry in B0→K⁎0γ decays has also been measured with the same data and found to be
ACP(B0→K⁎0γ)=(0.8±1.7(stat.)±0.9(syst.))%.
Both measurements are the most precise to date and are in agreement with the previous experimental results and theoretical expectations
First observation of the decay Bs0→K*0K*0
No full textThe first observation of the decay B0s→K∗0K∗0 is reported using 35 pb−1 of data collected by LHCb in proton–proton collisions at a centre-of-mass energy of 7 TeV. A total of 49.8±7.5 B0s→(K+π−)(K−π+) events are observed within ±50 MeV/c2 of the B0s mass and 746 MeV/c2 < mKπ < 1046 MeV/c2, mostly coming from a resonant B0s→K∗0K∗0 signal. The branching fraction and the CP-averaged K∗0 longitudinal polarization fraction are measured to be B(B0s→K∗0K∗0)=(2.81±0.46(stat.)±0.45(syst.)±0.34(fs/ fd))×10−5 and fL =0.31±0.12(stat.)±0.04(syst.)
Observation of the suppressed ADS modes B± → [π±K-/+ π+π-]D K± and B± → [π± K-/+π+π-]Dπ±
No full textAn analysis of and B± → DK± and B± → Dπ±
decays is presented where the D meson is reconstructed in the four-body final state K± π-/+π+π-. Using LHCb data corresponding to an integrated luminosity of 1.0 fb-1, first observations are made of the suppressed ADS modes B± →[π± K-/+π+π-]DK± and B± → [π± K-/+π+π-]Dπ± with a significance of 5.1 sigma and greater than 10 sigma, respectively. Measurements of CP asymmetries and CP-conserving ratios of partial widths from this family of decays are also performed. The magnitude of the ratio between the suppressed and favoured B± → DK ± amplitudes is determined to be rKB = 0.097 ± 0.011
Branching fraction and CP asymmetry of the decays B+→K0Sπ+ and B+→K0SK+
No full textAn analysis of B+ → K0
Sπ+ and B+ → K0
S K+ decays is performed with the LHCb experiment. The pp
collision data used correspond to integrated luminosities of 1 fb−1 and 2 fb−1 collected at centre-ofmass
energies of
√
s = 7 TeV and
√
s = 8 TeV, respectively. The ratio of branching fractions and the
direct CP asymmetries are measured to be B(B+ → K0
S K+
)/B(B+ → K0
Sπ+
) = 0.064 ± 0.009 (stat.) ±
0.004 (syst.), ACP(B+ → K0
Sπ+
) = −0.022 ± 0.025 (stat.) ± 0.010 (syst.) and ACP(B+ → K0
S K+
) =
−0.21 ± 0.14 (stat.) ± 0.01 (syst.). The data sample taken at
√
s = 7 TeV is used to search for
B+
c
→ K0
S K+ decays and results in the upper limit ( fc · B(B+
c
→ K0
S K+
))/( fu · B(B+ → K0
Sπ+
)) <
5.8 × 10−2 at 90% confidence level, where fc and fu denote the hadronisation fractions of a ¯b
quark
into a B+
c or a B+ meson, respectively
A Gigabit Transceiver for Data Transmission in Future High Energy Physics Experiments
No full textThe transmission of data from detectors in future high energy experiments will be driven by a number of requirements. In many cases, raw bandwidth is the strongest of these but other needs such as diverse functionality, compactness, low power and radiation resistance are equally important. The GigaBit-Transceiver project has been launched to provide a solution to these problems. The aim is to deliver a chip-set to build a bidirectional optical link transmitting and receiving serial data at 4.8 Gigabit/s. The project is based on three integrated circuits; a trans-impedance amplifier to receive signals from a photo-diode, a laser driver, and a transceiver containing a high-speed serialiser and de-serialiser. All of these have been successfully prototyped, and this paper will focus on the design and results from the serialiser/deserialiser prototype. This has been designed in commercial 130 nm CMOS with particular emphasis on enhancing its immunity to single-event-effects. The specific design features to achieve this will be described. The chip has been fully characterized in the lab, and jitter and bit-error-rate measurements are presented. The custom packaging of the chip will also be described together with the next steps foreseen in the project
Effective lifetime measurements in the B-s(0) -> K+K-, B-0 -> K+pi(-) and B-s(0) -> pi K-+(-) decays
No full textMeasurements of the effective lifetimes in the View the MathML source, B0→K+π− and View the MathML source decays are presented using 1.0 fb−1 of pp collision data collected at a centre-of-mass energy of 7 TeV by the LHCb experiment. The analysis uses a data-driven approach to correct for the decay time acceptance.
This is the most precise determination to date of the effective lifetime in the View the MathML source decay and provides constraints on contributions from physics beyond the Standard Model to the View the MathML source mixing phase and the width difference ΔΓs
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