We have developed a high-efficiency pulsed slow positron beam for experiments with orthopositronium in vacuum. The new pulsing scheme is based on a double-gap coaxial buncher powered by an RF pulse of appropriate shape. The modulation of the positron velocity in the two gaps is used to adjust their time-of-flight to a target. This pulsing scheme allows to minimize non-linear aberrations in the ...

The interaction of light with matter has been an intensely studied area both theoretically and experimentally. Lasers are one of the most important tools for such experimental research. Progress in this area has been linked to the evolving capabilities of lasers. There are two features of lasers that are of importance in the study of light matter interactions the pulse duration and intensity. R...

We demonstrate a photon-counting technique for detecting Bragg excitation of an ultracold gas of atoms. By measuring the response of the light field to the atoms, we derive a signal independent of traditional time-of-flight atom-imaging techniques. With heterodyne detection we achieve photon shot-noise limited detection of the amplification or depletion of one of the Bragg laser beams. Photon c...

This work treats degenerate four-wave mixing ~DFWM! in noncentrosymmetric materials, taking into full account the fact that the DFWM signal arises from third-order nonlinear optical effects as well as from two distinct combinations of second-order effects: second-harmonic generation plus difference frequency generation and optical rectification plus Pockels effect. Because of these second order...

Last year an intense electron beam produced by an induction accelerator was bunched using a Free Electron Laser and used to generate radio-frequency power by its passage through a resonant cavity. An improved version of this experiment has been carried out in the last few months. Our aims were mainly to extract a higher beam current from the FEL and to obtain a longer R-F pulse duration from th...

was used to deliver rectangular pulses for extracellular field stimulation of individual heart cells. We found that single frog and guinea pig ventricular myocytes are excitable with rectangular pulse field stimulation over a wide range of pulse durations, ranging from 10 msec to as little as 20 ,usec. The excitation field strength varies inversely with pulse duration as described by the Weiss-...

Pulse timing of the isolated pulsar PSR B1882-11 shows strong Fourier power at periods ≃ 1000, 500 and 250 d, correlated with changes in the pulse profile (Stairs, Lyne & Shemar 2000). We study the extent to which these data can be explained by precession of the star's rigid crust coupled to the magnetic dipole torque. We find that the correlated changes in the pulse duration and spin period de...

We analyzed the two-dimensional 2D electron momentum distributions of high-energy photoelectrons of atoms in an intense laser field using the second-order strong field approximation SFA2 . The SFA2 accounts for the rescattering of the returning electron with the target ion to first order and its validity is established by comparing with results obtained by solving the time-dependent Schrödinger...

Objectives: To compare between pulsed dye laser and podophyllin resin in treatment of genital warts regarding pain, number of sessions, clearance rate, and recurrence. Methods: Thirty-nine female patients were divided into two groups, the first group; 20 patients was treated with podophyllin resin, the second group 19 patients was treated with pulsed dye laser (Candela) 595nm, 1.5 ms pulse dura...

The propensity of molecules to spatially align along the polarization vector of intense, pulsed light fields is related to readily-accessible parameters (molecular polarizabilities, moment of inertia, peak intensity of the light and its pulse duration). Predictions can now be made of which molecules can be spatially aligned, and under what circumstances, upon irradiation by intense light. Accou...