Study of the transverse beam tails at LEP

The transverse beam profile in LEP has been studied. Non-Gaussian tails of the distribution have been limiting the maximum current that could safely be collided and are a potential source of backgroun d to the experiments. Scattering processes have been identified as a mechanism which launches particles to large amplitude. Simulations of the relevant scattering processes have been implemented in the tracking code DIMAD. Results from the tracking agree with measurement results for a single beam and for colliding beams with a low beam-beam tune shift. Tail measurements also helped in understandin g the dynamic aperture measurements at LEP

Transverse beam tails due to inelastic scattering

Non-Gaussian beam tails producing low beam lifetimes and background to the experimental detectors can be a serious performance limitation in colliding beam facilities. We describe simulations and measurement of non-Gaussian beam tails, performed on the e+ e- collider LEP, that revealed the importance of inelastic particule scattering as launching processes of particules to large amplitude

Observations and simulations of beam tails in LEP

Transverse beam tails have been measured in LEP using scraping collimators and loss monitors. Very significant non-Gaussian tails are present for colliding beams and high beam-beam tune shift. On a lower but still significant level, non-Gaussian tails are also present in the horizontal plane for a single beam. Comparison of measurements with detailed simulations allowed us to identify off-momentum particles produced by scattering processes as a source of significant transverse tails

Cavity-enhanced optical detection of carbon nanotube Brownian motion

Optical cavities with small mode volume are well-suited to detect the vibration of sub-wavelength sized objects. Here we employ a fiber-based, high-finesse optical microcavity to detect the Brownian motion of a freely suspended carbon nanotube at room temperature under vacuum. The optical detection resolves deflections of the oscillating tube down to 50pm/Hz^1/2. A full vibrational spectrum of the carbon nanotube is obtained and confirmed by characterization of the same device in a scanning electron microscope. Our work successfully extends the principles of high-sensitivity optomechanical detection to molecular scale nanomechanical systems.Comment: 14 pages, 11 figure

Trapped-Atom-Interferometer in a Magnetic Microtrap

We propose a configuration of a magnetic microtrap which can be used as an interferometer for three-dimensionally trapped atoms. The interferometer is realized via a dynamic splitting potential that transforms from a single well into two separate wells and back. The ports of the interferometer are neighboring vibrational states in the single well potential. We present a one-dimensional model of this interferometer and compute the probability of unwanted vibrational excitations for a realistic magnetic potential. We optimize the speed of the splitting process in order suppress these excitations and conclude that such interferometer device should be feasible with currently available microtrap technique.Comment: 6 pages, 6 figures, submitted to PR

Creating Ioffe-Pritchard micro-traps from permanent magnetic film with in-plane magnetization

We present designs for Ioffe-Pritchard type magnetic traps using planar patterns of hard magnetic material. Two samples with different pattern designs were produced by spark erosion of 40 $\mu$m thick FePt foil. The pattern on the first sample yields calculated axial and radial trap frequencies of 51 Hz and 6.8 kHz, respectively. For the second sample the calculated frequencies are 34 Hz and 11 kHz. The structures were used successfully as a magneto-optical trap for $^{87}$Rb and loaded as a magnetic trap. A third design, based on lithographically patterned 250 nm thick FePt film on a Si substrate, yields an array of 19 traps with calculated axial and radial trap frequencies of 1.5 kHz and 110 kHz, respectively.Comment: 8 pages, 5 figures Revised and accepted for EPJD, improved picture

Dynamically controlled toroidal and ring-shaped magnetic traps

We present traps with toroidal $(T^{2})$ and ring-shaped topologies, based on adiabatic potentials for radio-frequency dressed Zeeman states in a ring-shaped magnetic quadrupole field. Simple adjustment of the radio-frequency fields provides versatile possibilities for dynamical parameter tuning, topology change, and controlled potential perturbation. We show how to induce toroidal and poloidal rotations, and demonstrate the feasibility of preparing degenerate quantum gases with reduced dimensionality and periodic boundary conditions. The great level of dynamical and even state dependent control is useful for atom interferometry.Comment: 6 pages, 4 figures. Paragraphs on gravity compensation and expected trap lifetimes adde

Beam Tails in LEP

Beam tails have been measured in LEP using scraping collimators and loss monistors for separated and colliding beams. Significant non-Gaussian beam tails have been observed with colliding beams for high beam-beam tune shift parameters and bunch currents

Cold atoms in videotape micro-traps

We describe an array of microscopic atom traps formed by a pattern of magnetisation on a piece of videotape. We describe the way in which cold atoms are loaded into one of these micro-traps and how the trapped atom cloud is used to explore the properties of the trap. Evaporative cooling in the micro-trap down to a temperature of 1 microkelvin allows us to probe the smoothness of the trapping potential and reveals some inhomogeneity produced by the magnetic film. We discuss future prospects for atom chips based on microscopic permanent-magnet structures.Comment: Submitted for EPJD topical issue "Atom chips: manipulating atoms and molecules with microfabricated structures