Air bearing provides friction-free support for shaker system slip table

Air bearing system supports a shaker system slip table with minimum friction. At each corner of a square of grooves made on the table, a hole is drilled through the table and fitted with air connections. Air pressure is simultaneously fed to the four fittings forming an air bearing

Buffer gas cooling of YbF molecules

This thesis reports on the production and characterisation of the first slow and cold beam of YbF molecules using buffer gas cooling. These molecules are being used to measure the electron’s electric dipole moment, and an intense source of slow-moving molecules is desirable for this experiment. The molecules are loaded into a buffer gas cell via laser ablation where they thermalise with cold helium buffer gas. They are then detected inside the cell using laser absorption imaging and spectroscopy on the X2Σ+→A2II1/2 transition. The formation, diffusion and thermalisation dynamics of the molecules inside the cell are studied. Measurements of laser absorption versus intensity reveal that saturation of the absorption is due to a competition between optical pumping into dark states and repopulation of the addressed level by inelastic and velocity-changing collisions. A beam of YbF molecules is extracted through an aperture in the buffer gas cell and characterised using laser induced fluorescence detection. Peak fluxes of 1010 molecules per steradian per pulse, in the rotational and vibrational ground state, are obtained. The translational and rotational temperatures are in equilibrium with the cell temperature of 4 K. The forward velocity of the pulses can be varied between 130 m/s and 200 m/s by changing the buffer gas pressure. This source is an order of magnitude brighter and more than three times slower than a supersonic source of YbF molecules and provides an excellent starting point for improving the measurement of the electron’s electric dipole moment and for deceleration and trapping experiments. In order to reduce the helium load on the vacuum system and to shorten the molecular pulses, a second set-up, delivering the buffer gas into an open copper cylinder in pulses rather than in a continuous flow,is characterised and shows promising first results

Making the most of the volunteer experience for both the volunteer and the community based organization : what can be learned from a review of the literature and research

This literature review discusses the research and the implications of it in the areas of: volunteer motivation; screening, training and supporting volunteers; volunteer empowerment; age, gender and disability as they relate to the volunteer experience; particular issues that schools must consider when using volunteers; legal issues which impact agencies; and best practices that have been developed for volunteer programs

Exploring Potential Flaws and Dangers Involving Machine Learning Technology

This paper seeks to explore the ways in which machine learning and AI may influence the world in the future and the potential for the technology to be misused or exploited. In 1959 Arthur Samuel defined machine learning as “the field of study that gives computers the ability to learn without being explicitly programmed” (Munoz). This paper will also seek to find out if there is merit to the current worry that robots will take over some jobs based in cognitive abilities. In the past, a human was required to perform these jobs, but with the rise of more complex automation a person may not be necessary. Many of the sources cited throughout this paper focus on the innovation of machine learning and AI and how dangerous the over automation of the world could be. Machine learning and the resulting AI’s have their place in the world and more than likely they will do nothing but push the world towards a more fruitful future. Looking at potential risks of letting lines of code make important decisions is crucial given the consequences that negligence can have. There is a need to explore these topics because losing the human element in decision making can have some big implications if the AI is not programmed correctly. Machine learning has one of the greatest opportunities to impact the world. The need for caution however cannot be understated because of the potential dangers it may pose to jobs, security, and the overall stability of an ever changing world

Franck-Condon Factors and Radiative Lifetime of the A^{2}\Pi_{1/2} - X^{2}\Sigma^{+} Transition of Ytterbium Monoflouride, YbF

The fluorescence spectrum resulting from laser excitation of the A^{2}\Pi_{1/2} - X^{2}\Sigma^{+} (0,0) band of ytterbium monofluoride, YbF, has been recorded and analyzed to determine the Franck-Condon factors. The measured values are compared with those predicted from Rydberg-Klein-Rees (RKR) potential energy curves. From the fluorescence decay curve the radiative lifetime of the A^{2}\Pi_{1/2} state is measured to be 28\pm2 ns, and the corresponding transition dipole moment is 4.39\pm0.16 D. The implications for laser cooling YbF are discussed.Comment: 5 pages, 5 figure

Characterization of a cryogenic beam source for atoms and molecules

We present a combined experimental and theoretical study of beam formation from a cryogenic buffer gas cell. Atoms and molecules are loaded into the cell by laser ablation of a target, and are cooled and swept out of the cell by a flow of cold helium. We study the thermalization and flow dynamics inside the cell and measure how the speed, temperature, divergence and extraction efficiency of the beam are influenced by the helium flow. We use a finite element model to simulate the flow dynamics and use the predictions of this model to interpret our experimental results.Comment: 10 pages, 14 figure

Detection of nanoplastic by surface-enhanced Raman microscopy

Currently the extent of nanoplastic in the environment can only be estimated by extrapolation from the plastic waste that can be detected. To be able to quantify the whole extent of the problem, detection methods have to be developed that can also identify particles that are smaller than 1 $\mu$m. Here we employ surface-enhanced Raman scattering (SERS) to image and identify single nanoplastic particles down to 100 nm in size. We obtain an experimental enhancement factor of more than three orders of magnitude measured on a single plastic particle instead of averaging over a concentration. Our results contribute to the better understanding and employment of SERS for nanoparticle detection and present an important step for the development of future sensors.Comment: 9 pages, 7 figure