Investigation of Transient Effects in a Time-Dependent Magnetic Kicker

Buijsman, S.F. (2019) Investigation of Transient Effects in a Time-Dependent Magnetic Kicker. Master's Thesis / Essay, Physics.

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Abstract

The most recent developments in the experimental determination of the muon anomalous magnetic dipole moment (g - 2) have indicated a difference of 3.6 standard deviations between the theory and experiment. The muon g - 2 EDM experiment situated at J-PARC is designed to simultaneously measure g - 2 and the electric dipole moment (EDM) at low energies by measuring the spin precession vector. This is done by measuring trajectories of decay positrons, which are, by violation of parity conservation, preferably emitted in the direction of the spin of the muon in the muon rest frame. The J-PARC experiment aims to improve upon the previous measurement to a precision of 0.1 ppm (from 0.54 ppm, by BNL), in parallel with the experiment situated at Fermilab, which aims for similar precision goals. The muons are injected in a storage ring of a 33 cm radius in a 3 T magnetic field. A weak magnetic focusing field keeps the muons in the storage region. A time-dependent magnetic kicker brings the muons from the injection volume to the storage volume. Various systematic effects caused by the magnetic kicker have been investigated. The electric field induced by the time-varying kicker field has a negligible effect on the dynamics of the injected muons. The electric field decayed below the desired 10 mV/cm after about 150 ns after the kicker was switched off. The volume of acceptance was determined to reduce calculation time. The muon spin was successfully tracked using a numerical method that preserves the length of the spin vector. Oscillations in the pitch angle have been observed. The frequencies present in this oscillation correspond well with theory. Their values are found to be ω1 = 4.5 10^5 2 π rad/s and ω2 = 1.4 10^6 2π rad/s. Effects caused by retardation, transient currents and broadening of the current waveform due to dispersion have been investigated. Muon injection did not succeed for effective current speeds below 7/10 c. It has been shown that successful injection is prevented for a kicker coil of multiple turns. Retardation effects are negligible compared to transient and dispersion effects. Broadening of the current waveform prevents injection for a broadening greater than 1/12 ns for each ns of propagation time. To still successfully trap muons while taking these effects into account, the kicker parameters need to be adjusted accordingly. When these effects are taken into account, muon injection is expected to be successful.

Item Type:	Thesis (Master's Thesis / Essay)
Supervisor name:	Onderwater, C.J.G. and Jungmann, K.H.K.J.
Degree programme:	Physics
Thesis type:	Master's Thesis / Essay
Language:	English
Date Deposited:	08 Jul 2019 12:40
Last Modified:	18 Mar 2022 13:51
URI:	https://fse.studenttheses.ub.rug.nl/id/eprint/19995

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