, WP1 Meeting, RAL J. Pasternak Status and Recent Progress in the Muon FFAG Designs for the NF J. Pasternak, Imperial College, London / RAL STFC Work in collaboration and with contributions from: M. Aslaninejad (IC), J. Scott Berg (BNL), D. Kelliher (ASTeC/STFC/RAL), S. Machida (ASTeC/STFC/RAL), Y. Mori (Kyoto University), T. Planche (Kyoto University), H. Witte (JAI)

, WP1 Meeting, RAL J. Pasternak Outline of the talk Status of baseline IDS FFAG design (S. Berg, S. Machida). Studies of injection/extraction for IDS muon FFAG (D. Kelliher, J.P., M. Aslaninejad, H. Witte). Scaling FFAG options for low energy acceleration (Y. Mori, T. Planche). Summary and future plans.

, WP1 Meeting, RAL J. Pasternak Reference IDS Neutrino Factory Design nsFFAG

, WP1 Meeting, RAL J. Pasternak Introduction Motivations for Non Scaling FFAGs: quasi-isochronous –enables high frequency RF linear fields – gives huge DA and allows for simple magnets small orbit excursion – cost effective Main problems: TOF with amplitude injection/extraction Lattice choice Triplet with long drift: due to longest drift injection/extraction seems to be most feasible comparing to other lattices allows for symmetric injection/extraction, good performance but less cost-effective

, WP1 Meeting, RAL J. Pasternak It will be tested in EMMA soon, 2010!

, WP1 Meeting, RAL J. Pasternak Alternative solution Nonliner NS-FFAG, S. Machida (1) Due to natural chromaticity time of flight depends on amplitude, which introduces longitudinal blow-up and limits acceptance. The lattice with chromaticity correction is proposed to correct for this effect. Natural chromaticity Corrected chromaticity, study by S. Machida

, WP1 Meeting, RAL J. Pasternak Alternative solution - Nonliner NS-FFAG, S. Machida (2) Layout of FFAG with insertions Please see S. Machida’s talk for updates.

, WP1 Meeting, RAL J. Pasternak Introduction to injection/extraction Working assumptions: Try to distribute kickers to reduce their strengths. Apply mirror symmetric solution to reuse kickers for both signs of muons. FDFFFDD Septum Positive Muons Negative Muons Septum Kickers

, WP1 Meeting, RAL J. Pasternak Injection – Triplet, D. Kelliher Kickers Septum Horizontal scheme is feasible in trilet. Scheme is less demanding with respect to special magnet needs. It uses m long kickers at T and the 2.4 m long septum at 2 T. Please see D. Kelliher’s talk for updates.

, WP1 Meeting, RAL J. Pasternak D. Kelliher

, WP1 Meeting, RAL J. Pasternak Effects of special magnets Beams close to septum push the magnet aperture. Special magnets with higher aperture is needed in injection/extraction regions. Those magnets introduce the ring lattice symmetry breaking, which can cause accelerated orbit distortion. Current studies show that the effect is not dramatic, but more simulations are needed.

, WP1 Meeting, RAL J. Pasternak Preliminary ideas for kicker R&D PS PFN switch Transmission line Kicker Termination 3 independent Pulse Forming Networks (PFNs) and switches are needed for every muon train. Termination is very important to avoid reflections back to magnet (for injection). Current is most likely to high for thyratrons, but IGBTs should be OK. We want to push conventional kickers, but may also look at new ideas. Kicker R&D are just starting for FFAG accelerators within IDS! FFAG IDS kicker: size HxV (~ 0.3 x~ 0.3 m), field 0.1 T, I~ 30 kA, V~60 kV, rise time 1.5 us length 1.4 m PAMELA-FFAG kicker: size HxV (~ x~0.026 m), field T, I~ 9 kA, V~50 kV rise time 100 ns length 1 m Work in collaboration with H. Witte.

, WP1 Meeting, RAL J. Pasternak Current pulse, H. Witte

, WP1 Meeting, RAL J. Pasternak 3 Current pulses for 3 bunches, H. Witte

, WP1 Meeting, RAL J. Pasternak Kicker magnet simulations, M. Aslaninejad We need to update the aperture requirements for kickers!

, WP1 Meeting, RAL J. Pasternak What about the septum? Superconducting septum of similar parameters was designed and constructed for Jefferson Lab Hall A The very similar septum is needed for medical FFAG for carbon treatment We may need to subdivide the septum into normal and superconducting part. HTS screening may be applied. We are just starting the study in collaboration with JAI, Oxford.

, WP1 Meeting, RAL J. Pasternak Some thougths, which need to be discussed and challenged soon! Long drift triplet may work without insertion Short drift triplet seems to be more cost effective, but injection/extraction is more difficult. Insertion may be beneficial here, and only modest additional drift space could be OK (3-4 m). What is the effect of chromaticity correction on the injection/extraction scheme?

, WP1 Meeting, RAL J. Pasternak What needs to be done: Update of the aperture requirements for kickers. Update of kicker and pulse generator parameters. Effect of chromaticity correction on injection/extraction. Address the level of chromaticity correction versus DA. Insertion study for the short drift triplet (or other configuration ?). Error study (including the effect of injection/extraction special magnets and possibly insertion).

, WP1 Meeting, RAL J. Pasternak Updated Scaling FFAG Lattice, T. Planche

, WP1 Meeting, RAL J. Pasternak Beam dynamics studies, T. Planche

, WP1 Meeting, RAL J. Pasternak Preliminary horizontal injection Rad The injection was studied as extraction. 2 kickers 0.19 T, 0.96 m (0.3 m space between the kicker and the magnet) Beam separation ąbout 1 cm Septum 0.96 m, 4 T, beam separation of about 25 cm at the magnet. 4.6 GeV beam, 3 cm normalized acceptance 3.6 GeV, beam, 3 cm normalized acceptance beam, 3 cm normalized acceptance

, WP1 Meeting, RAL J. Pasternak Preliminary horizontal extraction Rad 2 kickers 0.39 T, 0.96 m (0.3 m space between the kicker and the magnet) Beam separation ąbout 1 cm Septum 0.96 m, 4 T, beam separation of about 8 cm at the magnet GeV beam, 3 cm normalized acceptance 11.6 GeV, beam, 3 cm normalized acceptance Rad

, WP1 Meeting, RAL J. Pasternak Current status of scaling FFAG option The scaling FFAG ring has a good DA. 6D Beam dynamics studies are very promising! Horizontal injection requires T kickers and 4 T septum. Extraction requires T for the current geometry. Fast betatron decoherence makes options with more than 2 kickers questionable. The effect of decoherence needs to be studied. At extraction 4 T septum gives only 8 cm beam separation. We need to study the vertical injection/extraction schemes. More drift length would be beneficial!

, WP1 Meeting, RAL J. Pasternak Baseline NS linear FFAG lattices have been optimised. Alternative Nonlinear NS lattice with insertions and partial chromaticity correction was proposed. Injection/extraction schemes in the baseline lattices (FODO and triplet) were evaluated. The current results suggest triplet lattice with long drift to be most promising (the baseline?). Scaling FFAG option for low energy muon acceleration ( GeV) compatible with 200 MHz RF was proposed. Work in progress on all aspects of muon FFAG towards the Fermilab IDS meeting (beam dynamics and injection/extraction including kicker R&D)! Summary