Tue18Apr20174:00 pmLewis 101
Colloquium: Measurements Of Beam Cooling In Muon Ionization Cooling Experiment
Tanaz A. Mohayai
Department of Physics
Illinois Institute of Technology
Measurements Of Beam Cooling In Muon Ionization Cooling Experiment
The international Muon Ionization Cooling Experiment, MICE, is a high energy physics experiment located at Rutherford Appleton Laboratory in the U.K., and its aim is to demonstrate muon beam cooling for the first time. When muons are produced from pion decay, they occupy a large volume in the position-momentum phase space and the process of reducing their volume is known as beam cooling. Several beam cooling techniques exist, but the ionization cooling is the only technique fast enough to be used for muons within their short lifetime. Ionization cooling occurs when the beam loses momentum through energy loss, while traversing a material. In MICE, commonly used figures of merit for cooling are the beam emittance reduction, the phase-space volume reduction, and the phase-space density increase. Emittance is the measure of the size of the beam, and with a reduced beam emittance or phase-space volume, more muons can fit in a smaller aperture of a cost-effective accelerator. This may enable the construction of a future high-intensity muon accelerators, such as a Neutrino Factory or a Muon Collider. To demonstrate beam cooling, MICE makes use of two scintillating-fiber tracking detectors, immersed in the constant magnetic fields of the Spectrometer Solenoid modules. These trackers, one upstream and one downstream of the absorber reconstruct and measure the position and momentum coordinates of individual muons, and the absorber provides the ionization energy loss required for beam cooling. The choice of absorber material is dependent on the achievable energy loss, and the aim is to maximize beam cooling through energy loss while minimizing beam heating from multiple Coulomb scattering. In addition, given the precision with which MICE aims to demonstrate beam cooling, it is necessary to develop analysis tools that can work around any effects which may lead to inaccurate cooling measurements. Non-linear effects in beam optics is one example of such effects and it can result in apparent emittance growth or beam heating. The Kernel Density Estimation, KDE technique is an analysis tool which is insensitive to these non-linear effects and measures the muon beam phase-space density and volume. This talk will give an overview of the recent MICE results, the emittance measurement technique in the recent MICE data, and the novel application of the KDE technique in MICE.