1. Particle Physics Group Meeting January 4 th – 5 th 2010 Commissioning EMMA, the Worlds First Non Scaling Fixed Field – Alternating Gradient Accelerator. Jimmy Garland4th/5th Jan 20101

2. Introduction EMMA (Electron Machine with Many Applications) is a proof of principle machine being built at the Daresbury Laboratory It is the worlds first NS-FFAG accelerator Participating bodies/institutions include: The University of Manchester The Cockcroft Institute ASTeC/STFC The Daresbury Science and Innovation Campus The construction and commissioning is currently underway. Currently my project will focus on the beam dynamics in EMMA for example the longitudinal phase space and how it changes with acceleration/rapid resonance crossing. Jimmy Garland4th/5th Jan 20102

3. What is an FFAG? In a conventional synchrotron the magnetic field is ramped up with increasing particle energy. This keeps the particles on the design orbit. This means a slow repetition rate/cycling of the accelerator => no good for applications where high current and quick cycling are required. FFAG’s use fixed-field magnets thus the particle radius is proportional to energy. Quicker cycling of the machine can be achieved. There are two types of FFAG… Jimmy Garland4th/5th Jan 20103

4. Scaling FFAG In a scaling FFAG the fields match and magnets are arranged such that the betatron tune (and orbit shape) is independent of energy. Jimmy Garland4th/5th Jan 20104

5. Non-Scaling FFAG In a non-scaling FFAG the lattice comprises a strong focusing lattice. The tune is energy dependent. The strong focusing elements and complex fields allow for a more compact design making the machine smaller. Jimmy Garland4th/5th Jan 20105

6. Parameters for EMMA EMMA is a 10-20 MeV electron machine. 16.5m in circumference. 1 – 20Hz repetition rate. Acceleration to desired energy in ~10’s of turns. Consists of 42 D-F quadrupole doublets. These are offset from the axis so as to provide dipole effects as well as strong focusing. Applications include: – Proton cancer therapy (PAMELA) – ADSR’s, using thorium seems most promising – Design for a muon accelerator Jimmy Garland4th/5th Jan 20106

7. EMMA Lattice F D Cavity 210 mm D 65 mm 55 mm Magnet Centre-lines High Energy Beam Low Energy Beam Jimmy Garland4th/5th Jan 20107

8. EMMA Lattice Jimmy Garland4th/5th Jan 20108

9. What I’ve been doing so far Modeling the injection line in MAD8. Matching the beam parameters from ALICE to EMMA. Jimmy Garland4th/5th Jan 20109

10. What I’ve been doing so far In order to probe the properties of the beam in EMMA we need to optimise ALICE and have a small enough emittance and energy spread. Emittance describes the beam distribution in phase space: where sigma’s represent in this case the physical particle distribution in the y-plane. Normalised beam emittance in EMMA is ~3000  mm·mrad. Must try to keep the emittance small before injection and inject at various places. Jimmy Garland4th/5th Jan 201010

11. What I’ve been doing so far Taking data from ALICE -> Emittance and (soon) energy spread. Jimmy Garland4th/5th Jan 201011

12. What I’ve been doing so far Put a YAG screen in at position 1, measure the RMS beam size 1. Then put a slit in at position 1 (to make the beam point like) and put a YAG screen in at position 2 and measure the beam size here. We will have the divergence of the beam over the distance between the two positions. RMS emittance can be obtained from the size and divergence of the beam over the length separating the slit and screen. Scan through solenoid currents with the slit to get emittance of beam as a function of current/field strength to find optimum magnet strength for lowest emittance. 1. RMS beam size is obtained by fitting an intensity Gaussian (with background) to the pixels obtained form a YAG screen image. Jimmy Garland4th/5th Jan 201012

13. What I plan to do next Complete emittance analysis. Take more data from ALICE and produce measurements for emittance and energy spread. Find optimum operating conditions in ALICE. Study the injection line model with GPT which takes account of space charge effects. Eventually study the beam in EMMA! Jimmy Garland4th/5th Jan 201013

14. Thanks For Listening! Jimmy Garland4th/5th Jan 201014

15. Extra slides if needed… Jimmy Garland4th/5th Jan 201015

16. Non-Scaling FFAG So in a non-scaling FFAG lattice the tune is energy dependent. The strong focusing elements and complex fields allow for a more compact design making the machine smaller. As the betatron tune and path length change with energy the beam must be accelerated fast to overcome resonances which could destroy the beam. In an NS-FFAG fast acceleration (~10’s of turns) to design energy is possible => faster cycling of the machine and potentially higher current. Jimmy Garland4th/5th Jan 201016