A high-resolution photoelectron velocity-map-imaging study is reported for the photodetachment of the atomic oxygen anion at 532 nm, where five of the six possible spin-orbit fine-structure transitions have been resolved. A resolution of ⌬E / E = 0.38% was achieved. Within the experimental uncertainty, each of the finestructure transitions has the same anisotropy, the averaged ␤ = −0.89͑1͒ consistent with previous, fine-structureunresolved, experimental and theoretical determinations.

Absolute differential cross sections for elastic scattering of electrons from sulfur hexafluoride (SF 6 ) have been measured at 11 incident energies between 2.7 and 75 eV and for scattering angles between 10 • and 130 • . The magnetic angle-changing device of Read and coworkers has been used to extend these measurements to backward angles (130 • -180 • ) for incident energies below 15 eV. The measurements reveal some substantial differences with several previous determinations and a reasonably good level of agreement with a recent close-coupling calculation.

A method of active field cancellation is described, which greatly reduces the stray magnetic field within the trap region of a Bose-Einstein condensation experiment. An array of six single-axis magnetic sensors is used to interpolate the field at the trap center, thus avoiding the impractical requirement of placing the sensor within the trap. The system actively suppresses all frequencies from dc to approximately 3000 Hz, and the performance is superior to conventional active Helmholtz cancellation systems. A method of reducing the field gradient, by driving the six Helmholtz coils independently, is also investigated.

Articles you may be interested inA Zeeman slower design with permanent magnets in a Halbach configuration Rev. Sci. Instrum. 82, 063115 (2011); 10.1063/1.3600897An efficient magneto-optical trap of metastable krypton atoms Rev.A method for optimizing the design and construction of a Zeeman slower coil is presented. Unlike traditional designs, the measured magnetic field profile very accurately matches the desired field profile, enabling significant advantages for loading a magneto-optic trap.

Abstract:We have developed and characterised a stable, narrow linewidth external-cavity laser (ECL) tunable over 100 nm around 1080 nm, using a single-angled-facet gain chip. We propose the ECL as a low-cost, high-performance alternative to fibre and diode lasers in this wavelength range and demonstrate its capability through the spectroscopy of metastable helium. Within the coarse tuning range, the wavelength can be continuously tuned over 30 pm (7.8 GHz) without mode-hopping and modulated with bandwidths up to 3 kHz (piezo) and 37(3) kHz (current). The spectral linewidth of the free-running ECL was measured to be 22(2) kHz (Gaussian) and 4.2(3) kHz (Lorentzian) over 22.5 ms, while a long-term frequency stability better than 40(20) kHz over 11 hours was observed when locked to an atomic reference. 175-210 (2012). 18. List of parts and instruments. We used an Innolume GM-1060-150-PM-250 gain module, a Thorlabs C240TME-1064 mounted aspheric lens, a Thorlabs GR13-1210 blazed diffraction grating, a Thorlabs KMSS/M kinematic mirror mount, a Thorlabs PA4FKW piezo chip, European Thermodynamics APH-127-10-25-S TEC modules, an Epcos S861 thermistor, and an AFW Technologies PISO-83-2-C-7-2-FB polarization maintaining in-fibre isolator in the construction of the laser. The laser was controlled using a custom-built current controller, ILX Lightwave LDT-5100 temperature controllers, and a PiezoDrive PDu-150CL piezo driver. The laser was frequency stabilised using a Brimrose TEM-250-50-10-2FP fibre-coupled AOM, an SRS SR510 lock-in amplifier, and a custom-built PI controller.