Modeling mode arrivals in the 1995 SWARM experiment acoustic transmissions

As part of the Shallow Water Acoustics in a Random Medium (SWARM) experiment, a 16 element WHOI vertical line array (WVLA) was moored in 70 m of water off the New Jersey coast. A 400-Hz acoustic tomography source was moored some 32-km shoreward of this array, such that an acoustic path was created that was anti-parallel to the primary propagation direction for shelf-generated internal wave solitons. The presence of these soliton internal waves in the acoustic waveguide causes significant coupling of energy between propagating acoustic modes, creating fluctuations in modal intensities and modal peak arrival times, as well as time spreading of the pulses. Two methods by which acoustic propagation and scattering in soliton-filled waveguides can be modeled are presented here in order to understand and explain the scattering observed in the SWARM field data. The first method utilizes the Preisig and Duda [IEEE J. Ocean. Eng. 22, 256-269 (1997)] Sudden Interface Approximation (SIA) to represent the solitons. The second method, which is computationally slower, uses a finely meshed, "propagated" thermistor record to simulate the solitons in the SWARM experiment waveguide. Both numerical methods are found to generate scattering characteristics that are similar to the SWARM field data.     

Suppression of recoil heating by an optical lattice

We report suppression of atomic heating by light scattering due to tight binding in a 3D far-off-resonant optical lattice. We show that rescattered spontaneously emitted photons do not heat trapped atoms when the scattering rate is much less than the trap vibrational frequency.     

Search for neutrino oscillations at the palo verde nuclear reactors

We report on the initial results from a measurement of the antineutrino flux and spectrum at a distance of about 800 m from the three reactors of the Palo Verde Nuclear Generating Station using a segmented gadolinium-loaded scintillation detector. We find that the antineutrino flux agrees with that predicted in the absence of oscillations excluding at 90% C.L. nu;(e)-nu;(x) oscillations with Deltam(2)>1.12x10(-3) eV(2) for maximal mixing and sin (2)2straight theta>0.21 for large Deltam(2). Our results support the conclusion that the atmospheric neutrino oscillations observed by Super-Kamiokande do not involve nu(e).     

Polarization decreases the specific heat of liquid 3He

We report on the first measurements of the polarization dependence of the specific heat of liquid 3He. Transient polarizations m of up to 70% were reached by using the rapid melting technique. The specific heat at 60-100 mK and 27 bars is found to decrease approximately as m(2), the reduction reaching at least 30% for m = 70%. These results contradict the nearly localized picture of 3He, and are in agreement with the idea that a large part of the specific heat is due to spin fluctuations.     

The Rotational Spectrum of OCCCS Revisited

The rotational spectrum of the linear chain molecule tricarbon oxide sulfide, OCCCS, was recorded at room temperature between 118 and 179 GHz using a new commercial millimeter-wave spectrometer. The observed transitions were analyzed together with hitherto unassigned transitions from measurements between 78 and 118 GHz. About 1900 rotational transitions of OCCCS in the vibrational ground state and in 13 excited bending states could be assigned, the latter including the eighth, ninth, and tenth excited state of the low-lying bending mode nu(7) as well as the second excited state of the bending mode nu(6). Besides the determination of effective constants for these newly identified vibrational states, our data also served to considerably improve the effective constants for some of the bending states already characterized in previous publications. Copyright 2000 Academic Press.     

Observation of B --> K(+/-) pi(0) and B --> (K)0 pi(0), and evidence for B --> pi(+)pi(-)

We have studied charmless hadronic decays of B mesons into two-body final states with kaons and pions and observe three new processes with the following branching fractions: beta(B-->pi(+)pi(-)) = (4.3(+1. 6)(-1.4)+/-0.5)x10(-6), beta(B-->K(0)pi(0)) = (14.6(+5.9+2.4)(-5.1-3. 3))x10(-6), and beta(B-->K(+)/-pi(0)) = (11.6(+3.0+1.4)(-2.7-1.3))x10(-6). We also update our previous measurements for the decays B-->K(+)/-pi(-/+) and B+/--->K(0)pi(+/-).     

Two-body B meson decays to eta and eta('): observation of B --> eta K*

In a sample of 19 x 10(6) produced B mesons, we have observed the decays B-->eta K(*) and improved our previous measurements of B-->eta'K. The branching fractions we measure for these decay modes are B(B+-->eta K(*+)) = (26.4(+9.6)(-8.2)+/-3.3)x10(-6), B(B(0)-->eta K(*0)) = (13.8(+5.5)(-4.6)+/-1.6)x10(-6), B(B(+)-->eta'K(+) = (80(+10)(-9)+/-7)x10(-6), and B(B(0)-->eta'K0) = (89(+18)(-16)+/-9)x10(-6). We have searched with comparable sensitivity for related decays and report upper limits for these branching fractions.     

Femtosecond surface vibrational spectroscopy of CO adsorbed on Ru(001) during desorption

Using time-resolved sum-frequency generation spectroscopy, the C- O stretch vibration of carbon monoxide adsorbed on a single-crystal Ru(001) surface is investigated during femtosecond near-IR laser excitation leading to desorption. A large transient redshift, a broadening of the resonance, and a strong decrease in intensity are observed. These originate from coupling of the C- O stretch to low-frequency modes, especially the frustrated rotation, that are highly excited in the desorption process.     

Partially coherent conical beams

We introduce a new class of partially coherent beams that can propagate over large distances without changing their transverse profiles and their coherence properties. Such beams are generated by an incoherent superposition of identical fully coherent beams of arbitrary form, whose axes lie on a cone.     

Diode laser frequency-noise suppression by >50dB by use of electro-optic parametric master oscillators

We demonstrate a novel frequency-stabilization scheme for laser diodes that is capable of linewidth reduction by more than 5 orders of magnitude. In this master-slave scheme the diode laser emission is frequency-offset phase locked to the emission of an electro-optic parametric oscillator (EOPO), and the laser diode is simultaneously used as the EOPO pump source. As a result the initial frequency fluctuations of the pump are reduced to the intrinsic noise level of the EOPO, which can be extremely small. We demonstrate that subhertz linewidths of the beat notes of the signals of two of these systems can be readily achieved if acoustic perturbations are suppressed.