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

2. Contents Muon FFAG design and EMMA EMMA Commissioning results
Future plans

3. Muon FFAG design and EMMA
EMMA Commissioning results
Future plans

4. 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.

5. 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.

6. 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.

7. 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.

8. 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/ 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.

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

10. Muon FFAG design and EMMA
EMMA Commissioning results
Future plans

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

12. 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

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

14. 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.

15. 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

16. 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

17. 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.

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

19. 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.

20. 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.

21. 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.

22. 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.

23. 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

24. 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.

25. Thank you.

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