Atomic Interactions in Precision Interferometry Using Bose-Einstein Condensates

We present theoretical tools for predicting and reducing the effects of atomic interactions in Bose-Einstein condensate (BEC) interferometry experiments. To address mean-field shifts during free propagation, we derive a robust scaling solution that reduces the three-dimensional Gross-Pitaevskii equation to a set of three simple differential equations valid for any interaction strength. To model the other common components of a BEC interferometer---condensate splitting, manipulation, and recombination---we generalize the slowly-varying envelope reduction, providing both analytic handles and dramatically improved simulations. Applying these tools to a BEC interferometer to measure the fine structure constant (Gupta, et al., 2002), we find agreement with the results of the original experiment and demonstrate that atomic interactions do not preclude measurement to better than part-per-billion accuracy, even for atomic species with relatively large scattering lengths. These tools help make BEC interferometry a viable choice for a broad class of precision measurements.Comment: 8 pages, 6 figures, revised based on reviewer comment

Electro-optic bunch diagnostics on ALICE

An electro-optic longitudinal bunch profile monitor has been implemented on ALICE (Accelerators and Lasers in Combined Experiments) at the Daresbury Laboratories and will be used both to characterise the electron bunch and to provide a testbed for electro-optic techniques. The electro-optic station is located immediately after the bunch compressor, within the FEL cavity; its location allows nearby OTR, beam profile monitors and Coherent Synchrontron Radiation (CSR) diagnostics to be used for calibration and benchmarking. We discuss the implementation and the planned studies on electro-optic diagnostics using this diagnostic station

Upconversion of a relativistic Coulomb field terahertz pulse to the near infrared

We demonstrate the spectral upconversion of a unipolar subpicosecond terahertz (THz) pulse, where the THz pulse is the Coulomb field of a single relativistic electron bunch. The upconversion to the optical allows remotely located detection of long wavelength and nonpropagating components of the THz spectrum, as required for ultrafast electron bunch diagnostics. The upconversion of quasimonochromatic THz radiation has also been demonstrated, allowing the observation of distinct sum- and difference-frequency mixing components in the spectrum. Polarization dependence of first and second order sidebands at ωopt±ωTHz, and ωopt±2ωTHz, respectively, confirms the χ(2) frequency mixing mechanism

Two-Photon Spectroscopy of the NaLi Triplet Ground State

We employ two-photon spectroscopy to study the vibrational states of the triplet ground state potential ($a^3\Sigma^+$) of the $^{23}$Na$^{6}$Li molecule. Pairs of Na and Li atoms in an ultracold mixture are photoassociated into an excited triplet molecular state, which in turn is coupled to vibrational states of the triplet ground potential. Vibrational state binding energies, line strengths, and potential fitting parameters for the triplet ground $a^3\Sigma^+$ potential are reported. We also observe rotational splitting in the lowest vibrational state.Comment: 7 pages, 3 figure

Avian Use of Rice-Baited Trays Attached to Cages with Live Decoy Blackbirds in Central North Dakota

For several decades, blackbird depredation of sunflower has been a continuous problem. Sunflower growers consistently place blackbirds in the top tier of problems associated with growing sunflower in the northern Great Plains. Many non-lethal tactics have been employed in an attempt to protect ripening sunflower from foraging flocks of blackbirds. Thinning cattail-choked wetlands to reduce roosting habitat, using pyrotechniques to frighten feeding birds, planting Wildlife Conservation Sunflower Plots to lure birds away from commercial plots, applying taste repellents, and adapting cultural methods such as block planting to synchronize ripening are just a few such tactics. Even so, the numbers of blackbirds migrating through the northern Great Plains can overwhelm non-lethal techniques. That is, in some circumstances there are too many blackbirds for non-lethal techniques to be effective. One avicide, DRC-1339, is registered for use as a lethal bait in the U.S. and North Dakota. The avicide is usually mixed with brown rice at a ratio of 1:25 (treated rice kernel to untreated rice kernels). Normally, the rice mixture is broadcast on the ground in the ripening or sprouting crop. Non-blackbirds are plentiful in ripening sunflower fields, causing a potential risk to these species with the use of DRC-1339. These granivorous non-blackbirds might eat treated rice, causing an unintentional loss. A number of species of songbirds and sparrows could be at risk. Also, ring-necked pheasants (Phasianus colchicus) and mourning doves (Zenaida macroura) are species of high concern. One potential method of avoiding non-blackbirds is to put live decoys (blackbirds) in cages in areas devoid of habitat to attract free-living blackbirds to bait trays attached to the top of the decoy cages. The intent is to reduce large concentrations of blackbirds that cannot be otherwise dispersed by non-lethal means. The objective of this study is to identify and quantify the avian species visiting the bait trays. Our goal is to develop an effective and environmentally-safe method for managing locally abundant blackbird populations

Photoassociation of Ultracold NaLi

We perform photoassociation spectroscopy in an ultracold $^{23}$Na-$^6$Li mixture to study the $c^3\Sigma^+$ excited triplet molecular potential. We observe 50 vibrational states and their substructure to an accuracy of 20 MHz, and provide line strength data from photoassociation loss measurements. An analysis of the vibrational line positions using near-dissociation expansions and a full potential fit is presented. This is the first observation of the $c^3\Sigma^+$ potential, as well as photoassociation in the NaLi system.Comment: 6 pages, 3 figure

Longtitudinal electron beam diagnostics via upconversion of THz to visible radiation

Longitudinal electro-optic electron bunch diagnostics has been successfully applied at several accelerators. The electro-optic effect can be seen as an upconversion of the Coulomb field of the relativistic electron bunch (THz radiation) to the visible spectral range, where a variety of standard diagnostic tools are available. Standard techniques to characterise femtosecond optical laser pulses (auto- and cross-correlators) have led to the schemes that can measure electron bunch profiles with femtosecond resolution. These techniques require, however, well synchronized femtosecond laser pulses, in order to obtain the desired temporal resolution. Currently, we are exploring other electro-optic variants which require less advanced laser systems and will be more amenable to beam based longitudinal feedback applications. The first results of one such new scheme will be presented in this paper

Convergence science in the Anthropocene: Navigating the known and unknown

Rapidly changing ecological and social systems currently pose significant societal challenges. Navigating the complexity of social-ecological change requires ap- proaches able to cope with, and potentially solve, both foreseen and unforeseen societal challenges. The emergent field of convergence addresses the intricacies of such challenges, and is thus relevant to a broad range of interdisciplinary issues. This paper suggests a way to conceptualize convergence research. It discusses how it relates to two major societal challenges (adaptation, transformation), and to the generation of policy-relevant science. It also points out limitations to the further development of convergence research