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Lord, Tom, 24 June 2020 13:39
Preliminary results prepared for presentation at conferences¶
Multiple Coulomb Scattering in Lithium Hydride Absorbers (Preliminary)¶
Multiple coulomb scattering is a well known electromagnetic phenomenon experienced by charged particles traversing materials. However, from recent measurements by the MuScat experiment it is known that the available simulation codes, specifically GEANT4, overestimate the scattering of muons in low Z materials. This is of particular interest to the Muon Ionization Cooling Experiment (MICE) which has the goal of measuring the reduction of a muon beam emittance induced by energy loss in low Z absorbers. Multiple scattering induces positive changes in the emittance in contrast to the reduction due to ionization energy loss. It therefore is essential that MICE measures multiple scattering for its absorber materials; lithium hydride and liquid hydrogen; and validate the multiple scattering against known simulations. MICE took data with magnetic fields off suitable for multiple scattering measurements in the spring of 2016.
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Energy Loss in Lithium Hydride and Hydrogen Absorbers (Preliminary)¶
The cooling term of the ionization cooling equation is given by the "Bethe equation". A better understanding of the equation in hydrogen and lithium hydride is necessary in order to make more realistic predictions of the emittance reduction.
Data has been taken for several different muon beams traversing the lithium hydride absorber.
MICE measures the momentum upstream and downstream of the absorber using information from the trackers combined with measurements of the time of flight.
Emittance Exchange in MICE (Preliminary)¶
The Muon Ionization Cooling Experiment, MICE, has demonstrated transverse emittance reduction through ionization
cooling. Transverse ionization cooling can be used either to prepare a beam for acceleration in a neutrino factory or
for the initial stages of beam cooling in a muon collider. Later stages of ionization cooling in the muon collider require
the longitudinal emittance to be manipulated using emittance exchange and reverse emittance exchange, where
emittance is exchanged from and to longitudinal phase space respectively. A wedge absorber within the MICE cooling
channel has been used to experimentally study reverse emittance exchange in ionization cooling. Parameters
for this test have been explored in simulation and applied to experimental configurations using a wedge absorber
when collecting data in the MICE beam.
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Normalized Transverse Emittance Reduction in MICE 'Flip' Mode¶
Low emittance muon beams are central to the development of facilities such as a Neutrino Factory or a Muon Collider. The international Muon Ionization Cooling Experiment (MICE) was designed to demonstrate and study the cooling of muon beams. Several million individual muon tracks have been recorded passing through a liquid hydrogen or a lithium hydride absorber. Beam sampling routines were employed to account for imperfections in beam matching at the entrance into the cooling channel and enable an improvement of the cooling performance. A study of the change in normalized transverse emittance in a flipped polarity magnetic field configuration is presented and the characteristics of the cooling effect are discussed.
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Transverse Emittance Change in MICE ‘Solenoid Mode’ with Muon Ionization Cooling¶
Emittance reduction of muon beams is an important requirement in the design of a next-generation Neutrino Factory or Muon Collider. Ionization cooling has been proposed to meet this requirement, whereby beam emittance is reduced by passing a beam through absorbing material. Tight focussing is required in both horizontal planes, which is achieved in many designs using solenoid focussing. Ionization cooling has been demonstrated in the Muon Ionization Cooling Experiment (MICE) in 'flip' mode, where the solenoid field flips polarity across the absorber. We present the performance of MICE in 'solenoid' mode, where the field polarity does not change across the absorber.
Updated by Lord, Tom over 2 years ago · 34 revisions