New Initiatives for PRISM J. Pasternak Imperial College London/RAL STFC

1. New Initiatives for PRISM J. Pasternak Imperial College London/RAL STFC J. Pasternak

2. Outline • Introduction and motivation • PRISM Task Force initiative • Possible work strategy and ring design options • First ideas • Summary and future plans J. Pasternak

3. Introduction and Motivations • As charge lepton flavor violation (cLFV) is strongly suppressed in the Standard Model, • its detection would be a clear signal for new physics! • Search for cLFV is complementary to LHC. • The - + N(A,Z)→e- + N(A,Z) seems to be the best laboratory for cLFV. • The background is dominated by beam, which can be improved. • The COMET and Mu2e were proposed. • The PRISM-FFAG ring was proposed for a next generation experiment in order to: • -reduce the muon beam energy spread by phase rotation, • -purify the muon beam in the storage ring. J. Pasternak

4. The PRISM-FFAG Task Force Initiative • The PRISM-FFAG Task Force was proposed and discussed during the last PRISM-FFAG workshop at IC (1-2 July’09). • The aim of the PRISM-FFAG Task Force is to address • the technological challenges in realising an FFAG based • muon-to-electron conversion experiment, but also to strengthen • the R&D for muon accelerators in the context of the Neutrino Factory and future muon physics experiments. • It was proposed to achieve a conceptual design of the PRISM machine at the end of 2010/beginning 2011. • The following key areas of activity were identified and proposed • to be covered within the Task Force:- the physics of muon to electron conversion,- proton source,- pion capture,- muon beam transport,- injection and extraction for PRISM-FFAG ring,- FFAG ring design including the search for a new improved version,- FFAG hardware R&D for RF system and injection/extraction kicker • and septum magnets. • The Task Force will use phone conferences and next PRISM-FFAG • workshops were proposed. J. Pasternak

5. Current Design Parameters – A. Sato V per turn ~2-3 MV p/p at injection =± 20% p/p at extraction =± 2% (after 6 turns ~ 1.5 us) h=1 J. Pasternak

6. Possible PRISM Task Force Design Strategy Option 1: Adopt current design and work out injection/extraction, and hardware Option 2: Find a new design They should be evaluated in parallel and finaly confronted with the figure of merit (FOM) (number of muons delivered to target/cost). Requirements for a new design: • High transverse acceptance (at least 38h/5.7v [Pi mm] or more). • High momentum acceptance (at least ± 20% or more). • Small orbit excursion. • Compact ring size (this needs to be discussed). • Relaxed or at least conserved the level of technical difficulties. for hardware (kickers, RF) with respect to the current design. J. Pasternak

7. Ring Design Options R Scaling FFAG Options: • standard lattice, • periodic with extended cell (for example 5 magnets per cell), • superperiodic (proposed by S. Machida) • advanced (proposed by Y. Mori and collaborators, see J-P.Lagrange’s talk) Non-Scaling FFAG Problems to be addressed: • confirmation of a large DA • currently no insertion scheme, • very difficult injection • TOF with amplitude J. Pasternak

8. Basic constraints • Energy acceptance depends on RF voltage and harmonic number. Observation: if we want to go for h=2, we need a factor of 2 more RF! • Synchrotron tune tells us about number of turns needed for phase rotation. Observation: for h=2 phase rotation is twice as fast (3turns). • If we want to lower the central momentum (keeping momentum acceptance), RF voltage goes down, but bucket starts to be more asymmetric (A. Sato proposed to look at 40 MeV/c). • Changing central momentum increases revolution time. This is good for kickers, but you need to be within the frequency range of MA cavities. C. Ohmori J. Pasternak

9. First look at Non-Scaling Design Short Drift 0.376 m Short Drift 0.376 m Long Drift 1.1 m Long Drift 1.1 m F Quad, 0.376 m B from -0.07 to 0.1 T Defocusing RBend, 0.376 m B from 0.34 to 0.31 T • Some parameters: • Lattice Symmetric FDF triplet • N 10 • p0 68 MeV/c • Circunference 40.84 m • (QH, QV)/cell at p0 (0.276, 0.189) • Drif length 2.2 m J. Pasternak

10. Orbit in NS-PRISM prototype lattice p0 +20% p0 p0 p0 -20% p0 m • Orbit excursion 0.38 m • Orbit is very linear with momentum MeV/c J. Pasternak

11. Tunes Tune/cell QH QV MeV/c • Chromaticity is relatively flat in horizontal plane. • Vertical tune excursion is large – edge focusing. • Tunes cross – potential problem! J. Pasternak

12. Dynamical aperture tests xp,rad • Tracking of large amplitude particles shows • no strong distortion • Tracking is done with hard-edge • approximation, tracking with soft edges • needs to be done. x, m yp,rad y, m J. Pasternak

13. First phase rotation simulations Red- particles at injection Black- no transverse amplitude Blue – large horizontal amplitude Pink – large vertical amplitude • Phase rotation performed with non ideal „sawtooth” RF voltage • ToF variation with amplitude introduces a small additional energy spread, • but it can be accepted . J. Pasternak

14. Summary and future plans • PRISM Task Force was created and started to work. • First lattice examples with advanced scaling (J-B. Lagrange) • and non-scaling lattices was designed. • Hardware development for RF is on the way (C. Ohmori). • Hardware work for the kicker and septum is starting. • (It was proposed to scale ISIS extraction kicker system to • the PRISM parameters in collaboration with RAL). • We are aiming at the CDR in 2010/2011. • You are welcome to join PRISM Task Force! J. Pasternak