Mike Jenkins and Ian Bailey

Positron Requirements of a New Collider CLIC SLCILC LHeC 6.0x10 12 e + /s 3.9x10 14 e + /s 4.0x10 16 e + /s 1.1x10 14 e + /s

Undulator-Based Positron Source

Based on OPERA 3D model created by Jim Rochford Image of ILC Undulator Prototype at RAL

Undulator-Based Positron Source Conversion Efficiency in Target (e + /γ) 7% Transport Efficiency through Source (FC) 80% Positrons within Damping Ring Acceptance (ILC) 67% e + /e - in Damping Ring2 γ/e - in Undulator200 ELI-NPCLICILCLHeC ~ x x x10 18

Efficiency of Positron Production

Ideal Helical Undulator Spectrum

Simulating Undulator Photon Spectra In order to test a non ideal helical undulator photon spectrum we need to be able to generate a photon spectrum from an arbitrary magnetic field map. HUSR developed at Cockcroft Institute by David Newton FluxCalc developed at Cockcroft Institute by Duncan Scott

HUSR: Particle Tracking HUSR utilizes Lie maps in the tracking of particles through a magnetic field z(m) x(m) y(m)

HUSR: Photon Spectra HUSR calculates the synchrotron radiation produced from a particle track at a number of observation points The electric field at each observation point is calculated using the retarded potential This field is then Fourier transformed to give the frequency spectrum of the observed radiation

Benchmarking HUSR

Optimising the Photon Spectrum

Short Undulators λ=11.5 mmλ=14.0 mm B (T)0.86 K The possibility of using a number of short undulators has been investigated Number of periods is 15 rather than 155 for ILC TDR Undulator module

Short 150 GeV

Short 250 GeV

Summary Undulator-based positron sources could provide the positron flux required by ILC and CLIC Further optimisation of positron source is possible Using new software tools we can now optimise the undulator Possibility to design an undulator to provide the required light for an experiment

Acknowledgements David Newton – University of Liverpool and Cockcroft Institute Duncan Scott – ASTeC and Cockcroft Institute Sabine Riemann, Andreas Schaelicke and Andriy Ushakov - PPS-Sim Group at DESY Jim Clarke and the HeLiCal collaboration

Photon Requirements LCLS CLIC LHeC ILC LCLS (1 KeV)CLICILCLHeC 1.2x x x x10 18

NbTi Helical Undulator B 0 (T)0.86 λ u (m) K0.92 γ/m/e Images of ILC Undulator Prototype at RAL * *Equation 1.9 From Klaus Flottmann’s Thesis

Nb 3 Sn Helical Undulator Based on OPERA 3D model created by Jim Rochford Z B 0 (T)0.985 λ u (m)0.01 K0.92 γ/m/e

‘Realistic’ Undulator Photon Spectra Spectrume + /e - (100m Undulator) Ideal0.87 Realistic0.93 *From Paper by B.M. Kincaid 1976, Eq 25

Growing Period Undulators z(m) x(m) y(m)

Off Axis Injection into Undulators z(m) x(m) y(m) z(m) x(m) y(m)

Summary Investigations into growing period undulators and effect of off axis electron trajectories is on going Photon and positron polarisation studies have been carried out Paper on undulator studies currently being written Positron source thesis to be submitted in Feb 2013