Search Results (7 total)

We describe the status of our effort to realize a first neutrino factory and the progress made in understanding the problems associated with the collection and cooling of muons towards that end. We summarize the physics that can be done with neutrino factories as well as with intense cold beams of muons. The physics potential of muon colliders is reviewed, both as Higgs factories and compact high-energy lepton colliders. The status and time scale of our research and development effort is reviewed as well as the latest designs in cooling channels including the promise of ring coolers in achieving longitudinal and transverse cooling simultaneously. We detail the efforts being made to mount an international cooling experiment to demonstrate the ionization cooling of muons.

Long term simulations of Hamiltonian dynamical systems benefit from enforcing the symplectic symmetry. One of the several available methods to perform this symplectification is provided by the recently developed theory of extended generating functions. The theory offers an infinite supply of generator types that can be used for symplectification. Using Hofer's metric, a condition for optimal symplectification is given. In the weakly nonlinear case, the condition provides a generator type that, based on the limited information available on the system, in general gives optimal results.

Recently there has been renewed interest in the influence of fringe fields on particle dynamics, due to studies that revealed their importance in some cases, as, for example, the proposed Neutrino Factory and muon colliders. In this paper, we present a systematic study of generic fringe field effects. Using as an example a lattice of the proposed Neutrino Factory, we show that fringe fields influence the dynamics of particles at all orders, starting with the linear motion. It is found that the widely used sharp cutoff approximation leads to divergences regardless of the specific fall-off shape of the fields. The results suggest that a careful consideration of fringe field effects in the design stage of small machines for large emittances is always recommended.

A method is introduced that provides an accurate and fast approximation of high-order maps of fringe fields and other fields that change along the reference trajectory. While the effects of main fields of optical elements can be determined very efficiently with differential algebraic (DA) methods via exponentiation of the respective propagator, the computation of high-order maps of nonstationary fields in general requires time-consuming DA integration. The method of symplectic scaling presented in this paper provides a very fast approximation of such maps by relating an arbitrary map to a specific previously computed map. This is achieved by a combination of geometric scaling and scaling with rigidity performed in a canonically perturbative treatment of a strength parameter. The method is useful for detailed analysis of nonlinear motion in particle optics, which in many cases is strongly influenced or even dominated by the presence of fringe fields. The use of the symplectic scaling method typically speeds up the computation of fringe-field effects by around two orders of magnitude and thus approaches speeds similar to that of the main-field calculation. The method has been implemented in the code COSY INFINITY; several examples from various subfields of beam physics are given to illustrate the accuracy and speed of the method. © 1996 The American Physical Society.

An analytical theory of arbitrary-order achromats for optical systems with midplane symmetry is presented. It is based on the repeated use of identical cells; but besides mere repetition of cells, mirror symmetry is used to eliminate aberrations. Using mirror imaging of a cell around the x-y and x-z planes, we obtain four kinds of cells: the forward cell (F), the reversed cell (R), the cell in which the direction of bend is switched (S), and the cell where reversion and switching is combined (C). Representing the linear part of the map by a matrix, and the nonlinear part by a single Lie exponent, the symplectic symmetry is accounted for and transfer maps are easily manipulated. It is shown that independent of the choice and arrangement of such cells, for any given order, there is a certain minimum number of constraint conditions that has to be satisfied. It is shown that the minimum number of cells necessary to reach this optimum level is four, and out of the sixty-four possible four-cell symmetry arrangements, four combinations yield such optimal systems. As a proof of principle, the design of a fifth-order achromat is presented. © 1996 The American Physical Society.

A method is presented that allows the reconstruction of trajectories in particle spectrographs and the reconstructive correction of residual aberrations that otherwise limit the resolution. Using a computed or fitted high order transfer map that describes the uncorrected aberrations of the spectrograph, it is possible to calculate a map via an analytic recursion relation that allows the computation of the corrected data of interest such as reaction energy and scattering angle as well as the reconstructed trajectories in terms of position measurements in two planes near the focal plane. The technique is only limited by the accuracy of the position measurements, the incoherent spot sizes, and the accuracy of the transfer map. In practice the method can be expressed as an inversion of a nonlinear map and implemented in the differential algebraic framework. The method is applied to correct residual aberrations in the S800 spectrograph which is under construction at the National Superconducting Cyclotron Laboratory at Michigan State University and to two other high resolution spectrographs.

Electronic intrasubband excitations are studied by means of resonant inelastic light scattering by a two-dimensional electron gas. The different effect of sharp excitonic intermediate states on depolarized and polarized scattering gives direct evidence for the collective behavior of the spin-density excitation in contrast to the band of single-particle excitations. The observed spin-density energy (0.9 meV) is at significantly lower energy than the single-particle energy (1.1 meV). This is due to the Coulomb exchange interaction in the electron gas.