Improved alternating gradient transport and focusing of neutral molecules

Polar molecules, in strong-field seeking states, can be transported and focused by an alternating sequence of electric field gradients that focus in one transverse direction while defocusing in the other. We show, by calculation and numerical simulation, how one may greatly improve the alternating gradient transport and focusing of molecules. We use a new optimized multipole lens design, a FODO-lattice beam transport line, and lenses to match the beam transport line to the beam source and to the final focus. We derive analytic expressions for the potentials, fields, and gradients that may be used to design these lenses. We describe a simple lens optimization procedure and derive the equations of motion for tracking molecules through a beam transport line. As an example, we model a straight beamline that transports a 560 m/s jet-source beam of methyl fluoride15 m from its source and focuses it to 2 mm diameter. We calculate the beam transport line acceptance and beam survival, for a beam with a velocity spread, and estimate the transmitted intensity for specified source conditions. Possible applications are discussed.Comment: 10 pages, 9 figures, one bi

Understanding the temperature and the chemical potential using computer simulations

Several Monte Carlo algorithms and applications that are useful for understanding the concepts of temperature and chemical potential are discussed. We then introduce a generalization of the demon algorithm that measures the chemical potential and is suitable for simulating systems with variable particle number.Comment: 23 pages including 6 figure

Teaching statistical physics by thinking about models and algorithms

We discuss several ways of illustrating fundamental concepts in statistical and thermal physics by considering various models and algorithms. We emphasize the importance of replacing students' incomplete mental images by models that are physically accurate. In some cases it is sufficient to discuss the results of an algorithm or the behavior of a model rather than having students write a program.Comment: 21 pages, 4 figures, submitted to the American Journal of Physic