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  • 2015AlrashdiPhD

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Studies in positron and gamma ray production for future facilities

Research output: ThesisDoctoral Thesis

  • Ayash Alrashdi
Publication date2015
Number of pages159
Awarding Institution
  • Lancaster University
<mark>Original language</mark>English


The next generation of particle colliders after the LHC (Large Hadron Collider) at CERN are likely to be high-precision electron positron colliders such as the ILC (International Linear Collider) or CLIC (Compact Linear Collider). This next generation of colliders will give new scope to explore particle interactions in more detail than in current accelerators. However, producing a sufficient numbers of positrons is a significant challenge. One of the most difficult problems associated with the production of positrons is designing a production target that will survive in an intense photon beam while rotating at high speeds to spread out the energy from the beam. In the first part of this thesis I present a solution to a torque problem affecting the positron production target of high-energy electron-positrons colliders. Typically, the target experiences a braking force due to immersing the wheel inside a strong magnetic field to improve the capture efficiency for positrons. Using OPERA 3D software, a large number of simulations were performed to explore the movement of the target wheel inside the field. I developed a new magnet design which could help to reduce the torque effects. I show that a decrease in the torque parallel to the drive shaft from 500 Nm to 20 Nm is possible in principle, while a torque of 10 Nm perpendicular to the drive shaft is predicted. Also, the baseline design of the ILC (International Linear Collider) positron source requires the production of an intense ux of gamma rays. In the second part of this thesis I present an investigation of different magnetic field maps and the trajectories of electrons passing through the undulator. I present an investigation of using the spent gamma ray beam of the ILC for additional applications, including nuclear physics. As a result of changing the collimator shape, as well as the parameters of the undulator magnets, I obtain spectra from numerical simulations using the HUSR/GSR software package. I show that a narrow bandwidth energy spectrum of 5% and photon flux of 1013 photon/s is possible in principle.