The Ghost Collider: developing particle accelerators with no beam transients

Present and future high-energy electron-positron colliders are limited by two effects: the energy required to accelerate the beams and the electromagnetic beam-beam disruption. The Ghost Collider is an innovative concept that circumvents both problems, based on Energy Recovery Linac (ERL) technology. 

The first key innovation is the placement of electron and positron bunches within the same acceleration bucket – one under acceleration, the other deceleration. The buckets are therefore electrically neutral, beam position monitors will register no current (hence “ghost”) and crucially when the beams are decelerated, the energy is recovered, a vital part of making the collider more sustainable.

The second key innovation is at the interaction point (IP); an electron bunch and a positron bunch collide with an electron bunch and a positron bunch from the opposite direction. These collisions are electrically neutral so there is no beam-beam disruption at the IP, at least to first order, eliminating the primary limit on luminosity in all other collider concepts. This is achieved with delay chicanes to allow accelerated electrons to reach the IP at the same time as accelerated positrons from one bucket behind.

The student will start by developing an understanding of existing Energy Recovery Linac (ERL) collider concepts, their motivations and drawbacks. They will learn a number of accelerator simulations codes and commence construction of initial simplified simulations of the proposed linac transport, arcs, and interaction region. In the first year, the focus will be on the linacs, then the various transport sections in the second year and finally the interaction point in the third year.

The thesis will describe the full layout of the ghost collider with all the innovative features fleshed out. The student will be supported by Dr Rob Apsimon and Dr Peter Williams from the Cockroft Institute and Dr Andrew Hutton from Jefferson Lab, who has developed the concept of the ghost collider. For further questions, please contact r.apsimon@lancaster.ac.uk in the first instance.

The student will become a member of the Cockcroft Institute and will participate in the Cockcroft Institute Education and Training Programme, whereby they will participate in a lecture programme over the first 2 years of study in addition to their work on their project. The candidate should have at least a 2:1 or equivalent in physics or engineering and have a solid understanding of mathematical concepts and theory.

Funding and eligibility: Upon acceptance of a student, this project will be funded by the Science and Technology Facilities Council for 3.5 years; UK and other students are eligible to apply, although overseas students may be required to secure additional funding. A full package of training and support will be provided by the Cockcroft Institute, and the student will take part in a vibrant accelerator research and education community of over 150 people. An IELTS score of at least 6.5 is required (or equivalent).