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Measuring and Modelling the Magnetic Field of the MICE Spectrometer Solenoids

Langlands, Joe (2018) Measuring and Modelling the Magnetic Field of the MICE Spectrometer Solenoids. PhD thesis, University of Sheffield.

Available under License Creative Commons Attribution-Noncommercial-No Derivative Works 2.0 UK: England & Wales.

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Muon accelerators offer precise measurements of the Higgs boson’s properties and the PMNS matrix parameters. To make muon accelerators possible, tertiary beams of muons must first be cooled to allow them to be accepted into the accelerator and have a useful luminosity. The Muon Ionisation Cooling Experiment aims to demonstrate the ionisation cooling technique. This method involves passing muons through an absorber material. MICE will demonstrate the method by measuring the emittance of a muon beam before and after it passes through an absorber material. The two spectrometer solenoids are critical to the experiment as they produce the magnetic fields which cause the muons to undergo helical trajectories, thus allowing the two scintillating fibre trackers to measure the emittance. The field produced by the spectrometer solenoids needs to be known and software models are required for the tracking algorithm and simulation packages. A custom made field mapping machine was produced for the task of measuring the field produced by the solenoids. Using the data from this machine, models of the field are produced using least squares fitting. The full model uses a two-step procedure. The first step calculates two fields with differing lengths and thicknesses about the as-built dimensions of the coil being modelled. Then these fields are mixed until the square residuals with the data are minimised. The residual field is calculated between the model and data. The next stage of the model solves Laplace’s equation to yield Fourier-Bessel expansions. The coefficients and phases of each term of the expansions are found by fitting to different parts of the residual field. The full model is then a sum of the mixed field and the Fourier-Bessel terms. The results of these models are compared with data and show decent agreement.

Item Type: Thesis (PhD)
Academic Units: The University of Sheffield > Faculty of Science (Sheffield) > Physics and Astronomy (Sheffield)
Identification Number/EthosID: uk.bl.ethos.770197
Depositing User: Mr Joe Langlands
Date Deposited: 01 Apr 2019 09:25
Last Modified: 25 Sep 2019 20:07
URI: http://etheses.whiterose.ac.uk/id/eprint/23398

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