Nonscaling FFAG design and EMMA experiment Shinji Machida ASTeC/STFC/RAL 18 January 2011

Contents Muon FFAG design and EMMA EMMA Commissioning results Future plans

Muon FFAG design and EMMA EMMA Commissioning results Future plans

IDR Muon FFAG Updated recently to have 5 m long drift space for injection/extraction (J Scott Berg.) Make injection/extraction optics reasonable. Ease the stringent hardware specifications. As a baseline design, kept linear nonscaling lattice. No chromaticity correction included. Simple and cost effective way to be competitive with RLA. No difference from ISS FFAG as far as beam dynamics is concerned. As Scott mentioned this morning, we have updated the FFAG design recently. Main difference is the 5 m long drift space which makes injection and extraction optics reasonable and also ease the stringent hardware specifications. As far as the ring optics is concerned, we kept linear nonscaling lattice, which means no chromaticitiy correction is included as a base line design. We think this is a simple and cost effective way to be competitive with RLA. Despite all these updates, it is reasonable to say that there is no difference from ISS FFAG as far as beam dynamics is concerned.

Where we are now? Hardware design and R&D (Jaroslaw Pasternak.) Superconducting magnet Kicker and septa Power supply for pulsed magnets Tracking under end to end simulation initiative Interface between other parts incl. inj/ext (David Kelliher.) Evaluate transmission of realistic particle distribution made at the upstream. So where we are now? We have started hardware design and R&D which Jaroslaw will talk about shortly. We also started the effort of end to end simulation in terms of interface between other accelerators, which includes injection and extraction design which David will talk about in the next talk. Eventually we will see transmission of realistic particle distribution made at the upstream and then pass it to the decay ring. That is a goal.

If FFAG works as expected? Do we have enough knowledge of this new machine? Design and construct the world first linear nonscaling Fixed Field Alternating Gradient Accelerator; EMMA. EMMA was (and still is) Electron Model for Muon Acceleration Although it is now called Electron Model for Many Applications Cost about £6.5 M (~£9 M) However, even more fundamental question is if FFAG works as we expected. In other words, do we have a correct model to understand the reality. Since the linear nonscaling FFAG is a completely new beast to the field, our immediate task is to show it.

Goals Rapid acceleration with large tune variation due to natural chromaticity. Serpentine acceleration or acceleration outside rf bucket. Large acceptance for huge muon beam emittance.

Muon FFAG and EMMA Requirement of rf is much lower, a factor of 1000. Ratio Momentum 12.6 – 25 GeV/c 10 – 20 MeV/c 1 : 0.001 rf voltage 1214 MV 2.28 MV 1 : 0.002 Number of cell 64 42 1 : 0.66 Circumference 667 m 16.6 m 1 : 0.025 QD/QF length 2.251/1.087 m 0.0777/0.0588 m 1 : 0.035/0.054 Straight section 5 m 0.2 m 1 : 0.04 Aperture ~ 300 mm ~ 30 mm 1 : 0.1 Let me compare parameters of Muon FFAG and EMMA. Muon FFAG’s momentum range is from 12.6 to 25 GeV/c whiereas the EMMA is about 1000 times lower. Consequently required rf voltage is also 1000 times smaller which is a good help to reduce the cost and the model much simpler. On the other hand, the number of cell is about the same. Since the machine circumference is only a few percent of the muon ffag, emma’s magnet length and straight section is also a few percent of muon ffag, Requirement of rf is much lower, a factor of 1000. Space is more packed in longitudinal than in transverse. Relatively large aperture magnets. Injection/extraction might be harder than Muon FFAG.

EMMA in pictures FQUAD Cavity DQUAD Ion Pump Ion Pump Ion Pump Girder

Muon FFAG design and EMMA EMMA Commissioning results Future plans

Four sector commissioning Beam image on screen at the end of 4 sectors. 22:37 on 22 June 2010

Complete ring A beam circulates first for three turns and then for thousands turns a few day later. on 16 August 2010 First Turn Second Turn

Measurement of basic parameters Time of flight Closed orbit Betatron oscillations Tune Dispersion

Source of COD Misalignment turns out worse than expected. Realignment during shutdown should make COD less than +/- 1 mm. horizontal vertical We observed synchrotron oscillations and compared with simulation. Synchrotron oscillation period suggests we have enough voltage for acceleration.

rf voltage Consistent synchrotron oscillation period in experiment and simulation suggests there is enough rf voltage. We observed synchrotron oscillations and compared with simulation. Synchrotron oscillation period suggests we have enough voltage for acceleration. expected Experiment set1

Toward acceleration Signal suggests only a few MeV gain or loss. simulation simulation However, we did not get any signal of serpentine acceleration in this case deceleration yet. If we have a serpentine acceleration, it should appear like this when you measure phase oscillation near unstable fixed point. If you compare with simulation, it seems that there is a hard wall somewhere between. This can be transverse or longitudinal. “hard wall” Experiment set1

Bottom line Serpentine channel acceleration is not demonstrated yet. COD was too large? Correction was not effective? Problem in rf? Stability of optics with very small dispersion function has been shown. Dependence of time of flight on beam momentum is partially confirmed.

Muon FFAG design and EMMA EMMA Commissioning results Future plans and EMMA upgrade

Where we are now? “Proof of principle” phase (~publication of a letter) June to October 2010: injection, lattice tuning, measure basic parameters, rf setup January to March 2011: acceleration/deceleration Detailed measurement (~publication of full papers) April 2011 to March 2012/13: list in the following page EMMA upgrade (~leading the FFAG community) For 5 to 10 years from now: list in the following page So where we are now. I should say we are in the proof of principle phase. The commissioning is started in June and spent a few months to try to inject a beam, tuning a lattice and measure transverse parameters and setup rf. Obviously acceleration or deceleration comes next.

Plan for the next three months “Acceleration/deceleration” has a priority. Improve correction algorithm to eliminate “hard wall”. More diagnostics should be ready and tested. Another 6~7 runs (each 3~4 days) until March 2010.

Plan for the next 1~2 yrs (1) more EMMA run Serpentine channel acceleration Set frequency and voltage to achieve desired parameters Accelerate point beam Measure mapping of longitudinal phase space Study parameter dependence of longitudinal phase space Dependence of transverse amplitude, etc. Acceleration with varying phase advance Effect of magnet errors Slowly cross individual resonance Examine effects of space charge, etc.

Plan for the next 1~2 yrs (2) more EMMA run (continued) Show large longitudinal and transverse acceptance Scan injected beam in horizontal phase space Scan injected beam in vertical phase space Scan injected beam in longitudinal phase space, etc.

Plan for the next 1~2 yrs (3) Installation of peripheral equipments Injection line additional diagnostics BPM at end of injection line to optimise septum entry angle Install collimators in diagnostics line Better understanding of off closed orbit beam Remote control room Give external labs control of EMMA and ancillaries for dedicated experiments Promotes collaboration and expertise exchange

Summary FFAG has to be benchmarked. EMMA is a machine which proves that our NF design of final acceleration works. So far, no big surprise. In two years, we will gain much more knowledge, both design and operational view point, on a linear nonscaling FFAG. Just in time to be integrated to RDR. In summary, EMMA is the machine which proves that our NF design of final acceleration works. So far, no big surprise. In two years, we will gain much more knowledge, both design and operational view point, on a linear nonscaling FFAG. Hopefully, these are just in time to be integrated to RDR.

Thank you.

ALICE and EMMA at Daresbury Accelerators and Lasers in Combined Experiments Parameter Value Nominal Gun Energy 350 keV Injector Energy 8.35 MeV Max. Energy 35 MeV Linac RF Frequency 1.3 GHz Max Bunch Charge 80 pC Emittance 5-15 mm-mrad EMMA