Small proton therapy accelerator by non-scaling FFAG

1. Small proton therapy accelerator by non-scaling FFAG Dejan Trbojevic-BNL, Eberhard Keil-CERN, and Andrew Sessler-LBL • Introduction: • Proton/carbon therapy – very fast growing field – very large number of facilities. • competition within proton therapy machines today: synchrotrons, cyclotrons, FFAG’s, …. • IBA, Siemens, Varian-ACCEL, Hitachi, Austron, … • Is there a reason to compete? price, circumference, fastest treatment rate, scanning-(treatment length), total ammount of steel • Properties of the lattice: • Basic cell orbits • radius, magnetic fields, aperture (orbit offsets), betatron functions, energy range, available drift space for cavities and exctraction/injection … • Acceleration: • Fast phase adjustments each turn- similar to the harmonic number jump. • Results from the six dimensional tracking studies • Concerns: • resonance crossing, fringe fields, emittance preservation, exctraction/injection, size of the RF power … • Summary FFAG08 Manchester Workshop – Dejan Trbojevic

2. Introduction hadron therapy: From Steve Peggs PAC07 talk: • 1 in 3 Europeans will confront some form of cancer in their lifetime. • Cancer is the 2nd most frequent cause of death. • Hadron therapy [protons, carbon, neutrons] is 2nd only to surgery in its success rates. • 45% of cancer cases can be treated, mainly by surgery and/or radiation therapy. FFAG08 Manchester Workshop – Dejan Trbojevic

3. Introduction: • Hadron (proton, carbon, neutron) therapy machines today: • synchrotrons, cyclotrons, FFAG’s, …. • Private companies producing them: IBA, Siemens, Varian-ACCEL, • Hitachi, ……. • Are there reasons to get involved? • Price might be to high? • Size might be to large for a hospital? circumference, magnets? • Rate for treatment could be faster? • A total ammount of steel could be smaller? • The energy and intensity modulation could be improved? FFAG08 Manchester Workshop – Dejan Trbojevic

4. Experimental results from: NSRL Laboratory at Brookhaven National Lab - Adam Rusek Very similar to the body cell density Ion: H+ Peak position: 26.1 cm in high density polyethylene (r=0.97 gr/cm3) Kinetic Energy: 205.0 MeV/n LET(in water): 0.4457 KeV/mm FFAG08 Manchester Workshop – Dejan Trbojevic

5. Experimental results from: NSRL Laboratory at Brookhaven National Lab - Adam Rusek Ion: C6+ Peak position: 8.375 cm in high density polyethylene (r=0.97 gr/cm3) Kinetic Energy: 200.2 MeV/n LET(in water): 16.23 KeV/mm FFAG08 Manchester Workshop – Dejan Trbojevic

6. Orbit offsets and dimensions in the cell L=1.12 m ½ F 14.1 cm D ½ F 8.21 8 cm 2.6 -2.5 -6.9 -10.1 38 cm ½ QLf=44 cm/2 QLd=22 cm ½ Ff = ½ 0.15271631 Fd=0.1090831 ½ Ff = ½ 0.15271631 FFAG08 Manchester Workshop – Dejan Trbojevic

7. The whole ring with all elements: 24 doublets 12 cavities Three kickers Circumference = 26.88 m D=8.56 m r=4.278 m FFAG08 Manchester Workshop – Dejan Trbojevic

8. Small proton therapy machine FFAG08 Manchester Workshop – Dejan Trbojevic

9. Tunes vs. momentum 250.0 MeV Ek=30.96 MeV FFAG08 Manchester Workshop – Dejan Trbojevic

10. Betatron Functions Dependence on Momentum FFAG08 Manchester Workshop – Dejan Trbojevic

11. Magnetic Properties: Offsets at F dp/p x0ff(m) 50 0.140638 40 0.111097 30 0.082114 20 0.053819 10 0.026376 0 0.000000 -10 -0.025024 -20 -0.048317 -30 -0.069370 -40 -0.087506 -50 -0.101838 LBD = 22 cm LBF = 30 cm Gd = -14.3 T/m Gf= 8.73 T/m Bdo= 0.804 T Bfo= 0.563 T Values of the magnetic fields at the maximum orbit offsets: Bd max-= 0.804 + (-14.3)*(-0.0484) = 1.496 T Bd max+= 0.804 + (-14.2)*(0.107) = -0.715 T Bf max+= 0.563 + 8.73 * 0.141 = 1.794 T Bf max- = 0.563 + 8.73 * (-0.102) = -0.327 T Minimum horizontal aperture: Amin=0.140638+0.101838+6s ~ 26 cm Offsets at D dp/p x0ff(m) 50 0.107354 40 0.083583 30 0.060737 20 0.039014 10 0.018662 0 0.000000 -10 -0.016560 -20 -0.030484 -30 -0.041077 -40 -0.047447 -50 -0.048481 FFAG08 Manchester Workshop – Dejan Trbojevic

12. Acceleration: The total stored energy in the cavity is related to the amplitude of the RF voltage: angular resonant frequency is wr Electron gains energy: FFAG08 Manchester Workshop – Dejan Trbojevic

13. Acceleration: 26.88 meter circumference 22 MeV < proton kinetic energy < 250 MeV, 0.24 <  < 0.61 Central rf frequency = 374 MHz FFAG08 Manchester Workshop – Dejan Trbojevic

14. Acceleration Harmonic number variation FFAG08 Manchester Workshop – Dejan Trbojevic

15. Requires a loaded quality factor Q=50 Full horizontal aperture 28 cm Full vertical aperture 3 cm, R/Q = 33 Ohm (circuit) for beta=0.24 FFAG08 Manchester Workshop – Dejan Trbojevic

16. The cavity is about $1million. A 100 kW driver is about $1 million Imagine a bunch train that fills about half the ring at injection We have about 80 nanoseconds to change the cavity frequency when there is no beam (depends on energy) With Q=50 and fres=370 MHz the exponential decay time for the field is 43 nanoseconds. Two e-folding times is pretty good so I’ll assume the voltage is limited by power Can take about 20 kV of synchronous voltage. FFAG08 Manchester Workshop – Dejan Trbojevic

17. Accelerating cavity – Mike Blaskiewicz: The voltage scales with beam velocity as FFAG08 Manchester Workshop – Dejan Trbojevic

18. 24 cells – twelve cavities 30 kV per cavity ~ 1300 turns: going through the third order resonance - horizontal phase space 400 1 900 53 102 4 500 150 55 1000 37 63 164 600 1100 73 49 200 700 1200 52 87 300 800 1340 FFAG08 Manchester Workshop – Dejan Trbojevic

19. 24 cells – twelve cavities 30 kV per cavity ~ 1300 turns: going through the third order resonance - vertical phase space 956 1187 695 829 1 turn number 15 1193 857 704 1007 420 733 886 1200 1138 507 807 1157 618 916 1300 FFAG08 Manchester Workshop – Dejan Trbojevic

20. Blow up from the third order resonance in x,x’ ~1.3 FFAG08 Manchester Workshop – Dejan Trbojevic

21. Blow up from the third order resonance in y,y’ ~1.9 FFAG08 Manchester Workshop – Dejan Trbojevic

22. 24 cells – twelve cavities 30 kV per cavity ~ 1300 turns: going through the third order resonance - longitudinal phase space 1 600 55 10 1000 90 30 58 2 15 100 700 42 1100 61 3 18 200 47 1200 800 400 5 23 65 49 7 28 51 70 500 900 1300 FFAG08 Manchester Workshop – Dejan Trbojevic

23. Blow up from the third order resonance in long. space FFAG08 Manchester Workshop – Dejan Trbojevic

24. 24 cells – twelve cavities 30 kV per cavity ~ 1300 turns: third order resonance avoided, no random errors: x, x’ phase space 1 400 900 50 10 60 1000 500 1100 20 100 600 30 200 700 1200 40 300 800 1350 FFAG08 Manchester Workshop – Dejan Trbojevic

25. 24 cells – twelve cavities 30 kV per cavity ~ 1300 turns: third order resonance avoided, no random errors: y, y’ phase space 900 1 20 200 500 1000 300 31 505 2 1109 401 694 53 3 1230 800 407 100 10 1300 FFAG08 Manchester Workshop – Dejan Trbojevic

26. 24 cells – twelve cavities 30 kV per cavity ~ 1300 turns: Third order resonance avoided, no random errors - longitudinal phase space 1 12 6 17 1000 600 7 18 13 2 700 1100 19 14 46 8 3 800 1200 4 15 96 9 900 1300 500 5 16 11 FFAG08 Manchester Workshop – Dejan Trbojevic

27. 731 850 941 35 2 1036 12395 1 77 506 Blow up in x, x’ due to the random errors of 10-3 third order avoided 12395/12=1032 FFAG08 Manchester Workshop – Dejan Trbojevic

28. Blow up in x, x’ due to the random errors of 10-3Third order avoided xo xf xf /xo~1.8 Bmax~1.95 T @x=xmax FFAG08 Manchester Workshop – Dejan Trbojevic

29. Blow up in y, y’ due to the random errors of 10-3third order avoided y’o y’f yo yf yf /yo~1.4 FFAG08 Manchester Workshop – Dejan Trbojevic

30. MOTIVATION • Comparable (synchrotrons ~C=60m) or smaller size (cyclotrons are smaller but definitelly require large ammount of steel). • Fast acceleration rate. • Energy scanning simple: single turn exctraction at required energy. • No radiation loss (cyclotrons have unavoidable activation due to losses inside of cyclotrons as well as from the raster to allow the required energy range. • Easy to operate because of the fixed and linear dependence of the magnetic field. • Small orbit offsets – small aperture. • RESONANCE crossing • End magnetic field effect • Large power for the RF CONCERNS: FFAG08 Manchester Workshop – Dejan Trbojevic

31. Additional subjets: FFAG08 Manchester Workshop – Dejan Trbojevic

32. Lattice got simplified with smaller number of magnets: FFAG08 Manchester Workshop – Dejan Trbojevic

33. Basic cell of non-scaling FFAG small therapy accelerator FFAG08 Manchester Workshop – Dejan Trbojevic

34. Small proton non-scaling FFAG accelerator for energy range of 1.35-12 MeV • Orbits and offsets during acceleration. • Magnets: Dimensions, gradients and fields • Ring • Acceleration • Summary Dejan Trbojevic and Sandro Rugierro FFAG08 Manchester Workshop – Dejan Trbojevic

35. Orbits during acceleration and offsets in one cell 25 cm 8.30 mm Ek=12 MeV -7.10 mm 6 cm Ek=1.35 MeV QLF/2 = 17/2 cm BLD =10 cm QLF/2 FFAG08 Manchester Workshop – Dejan Trbojevic

36. Betatron Functions FFAG08 Manchester Workshop – Dejan Trbojevic

37. Dimensions, Gradients and Magnetic Fileds Kinetic energy range for protons: Emin = 1.35 MeV <-> Emax = 12 MeV Bending angles - both magnets bend positive: ANGBD = 0.145444104332861 rad ANGBF= 0.203621746066005 rad Rigidity and central momentum: BRHO = 0.334766674280 Tm For dp/p=+-50% Bending fields in the Focusing and Defocusing combuned function magnets: BYQ = 0.400975145538842 T BYD= 0.486898391011451 T Gradients in T/m: GBF= 8.70 T/m GBD=-12.5 T/m Dimensions: QLF=0.17 m BL =0.10 m Drift between magnets = 6 cm Drift for cavities and kickers 25 cm. Maximum magnetic fields: BF max = 0.401 + 8.70 * 0.083 = 1.25 T (12 kG ) BD max = 0.4869 + (-12.5) * (-0.035) = 0.95 T FFAG08 Manchester Workshop – Dejan Trbojevic

38. Ring – circumference = 10.44 m, radius 1.66 m r = 1.66 m FFAG08 Manchester Workshop – Dejan Trbojevic

39. Acceleration: same as for the proton therapy machine FFAG08 Manchester Workshop – Dejan Trbojevic