1. Present and possible future schemes for hadron therapy linacs Alberto Degiovanni for the ADAM team HG2017 Workshop , Valencia

2. Outline Present status of LIGHT Layout First results New developments
Possible new schemes
Discussion

3. LIGHT (Linac for Image Guided Hadron Therapy) Overview
Proton Source
Modulator-klystron systems
Radio Frequency Quadrupole (RFQ)
Side Coupled Drift Tube Linac (SCDTL)
Coupled Cavity Linac (CCL)

4. LIGHT Main Parameters Parameter Value Unit Length ~25 m Max. Energy
230
MeV
Output Peak Current
(at the end) μA
Pulse Length
0.5-5 μs
RF Frequency
MHz
Max. Repetition Rate
200 Hz
Peak RF Power
~60 MW

5. LIGHT (Linac for Image Guided Hadron Therapy) @point 2
5 MeV
37.5 MeV
70-90 MeV
0.04 MeV

6. Proton Source Quantity Value Unit Output Energy 40 ± 0.4 keV
Output pulsed Current
Range: [1-300] ± 2% µA
Current ripple during flattop
± 1 %
Pulse to pulse current reproducibility
± 2-3
Repetition rate
Range: [5-200] Hz
Beam pulse width
Range: [0.5-5] µs

7. Proton source test results
Example of emittance measurements and corresponding rms emittances (white) with the representation of the RFQ acceptance ellipse (red).

8. The Radio Frequency Quadrupole (RFQ)
High frequency RFQ designed by CERN
4 vanes type
750 MHz
4 modules - 2 m
5 MeV energy gain
Section
RFQ
RF frequency [GHz]
0.749
Energy [MeV]
0.04-5
Length [m] 2
Foto piu’ recente

9. RFQ test results 5 MeV Results from the RFQ commissioning with beam
Profile and energy measurements
Comparison of measured and expected beam
profiles at the spectrometer profile monitor
calculated average beam energy from the spectrometer measurement is 5.07 MeV (expected energy 5.0 MeV)
Energy spread: measured rms energy spread is 7.0 keV (expected value is 7.5 keV)
Emittance
The expected rms emittance is 0.33 p.mm.mrad in both planes
5 MeV

10. The Side Coupled Drift Tube Linac (SCDTL)
Designed in collaboration with ENEA (Frascati, I)
Manufactured at TSC/VDL
Section
SCDTL
RF frequency [GHz]
2.998
Energy [MeV]
5-37.5
Length [m]
6.2

11. The Coupled Cavity Linac (CCL)
Section
CCL
RF frequency [GHz]
2.998
Energy [MeV]
Length [m]
15.5
Designed by ADAM
Manufactured by VDL
4 modules already conditioned

12. SCDTL and CCL E-field measurements

13. Fields in the CCL accelerating cells

14. Experience with conditioning and operation

15. Filling times module Q0 Qloaded τ [ns] CCL1 7320 3660 389 CCL2 7820
3910
415
CCL3
8200
4100
435
CCL4
8620
4310
458
CCL5
8940
4470
475
CCL6
9000
4500
478
CCL7
9800
4900
520
CCL8
10100
5050
536
CCL9
10400
5200
552
CCL10
10600
5300
563
CCL11
10820
5410
574
CCL12
11200
5600
595
CCL13
11520
5760
612
1.5
1.0 us

16. Some RF gymnastics – reducing the filling time

17. Energy and Intensity modulations
pulsed source
Einj
active energy variation
70 <E < 230 MeV
Klystron RF pulse
RF power into the tanks
Proton pulses from source
5.0 μs
Active energy modulation
Rep rate 200 HZ
~ 5 ms
Active intensity modulation
time I P
The cyclinac concept, proposed by TERA Foundation foresees the use of a LINAC booster combined with a MeV cyclotron as injector.
The use of linacs for protontherapy is very well suited for 3D spot scanning.
Protons are provided by an external pulsed source and pre-accelerated by the cyclotron.
The extracted protons are then boosted by the linac, that is divided in a certain number of modules each one powered by a compact modulator-klystron system with a typical peak power in the order of 10 MW with a repetition rate up to 200 Hz.
The modularity of the linac allows to achieve the active beam energy modulation. By switching ON and OFF the linac modules, and by reducing the power of the last active one, one can vary the energy of the beam from pulse to pulse by electronic means and without the need of absorbers.
The beam intensity can also be varied by changing the current from the pulsed source.

18. A modular approach towards industrialization
Unit Systems
Accelerating System
Control System
Cooling System
Focusing System
RF Network System
RF Power System
Support System
Vacuum System
Accelerating System
Control System
Cooling System
Focusing System
RF Network System
RF Power System
Support System
Vacuum System

19. Transverse beam optics
A FODO lattice is used to keep the beam focused along the linac
Small aperture Permanent Magnet Quadrupole (PMQ):
+ no power consumption !
+ strong gradient possible
+ reduced size and cost !
- Precision alignement needed !
BJA Magnetics

20. Energy modulation

21. Accelerating gradient and real estate gradient
Presence of electric field free spaces (for PMQ and flanges!) reduces real estate gradient!
Typical filling factor is ~ 70-75%

22. TW first proposal in X-band
X-band travelling wave structure design for TERA (A.Grudiev, 10/12/2008)
Reducing the space for focusing element along the beam path!
Strong magnetic field needed!

23. Conservative/safety aspect in LIGHT 1
Power from klystron: 7.5 MW
P_loss wg network: ~ 15%
Power available per unit: ~ 6.4 MW
Max power used: ~5 MW
Power safety/operational margin: ~ 28%
RF network includes Isolator for protection of the klystron from reflected power.
Part of RF network under SF6 !
LIGHT: MeV
Peak power [Mw] 48
Total length [m]
12.3
Active length [m]
9.5
Fill factor
0.77
Number of kl. 8

24. Accelerator shielding
Example of shielding impact on the foot-print (only accelerator is considered, since treatment room will be all the same independent of accelerator)

25. TULIP all-linac with new btw structures
BTW – MB klystrons
Btw: MeV
Peak power [Mw]
108
Total length [m]
7.7
Active length [m]
4.4
Fill factor
0.57
Number of kl. 18
SCDTL
RFQ

26. Peak surface fields RFQ IH-750 DTL-3000 BTW-3000 Frequency [MHz] 750
Avg gradient E0 [MV/m] -
5.7 16 50
Peak Es [MV/m]
~ 50
150
200
Peak Sc [MW/mm2]
0.036
0.5
0.75

27. CABOTO: CArbon BOoster for Therapy in Oncology

28. Shorter linac = higher power !
Gradient vs Power
L = n*lc
Shorter linac = higher power !

29. Conclusion
First prototype of LIGHT is under construction and being installed and tested with beam at CERN P2
Conservative design for version 1 – (length vs power)
New developments are ongoing in the field, collaboration TERA-CLIC
New TULIP and CABOTO designs takes advantages of novel TW structures and future spread of High Efficiency MB klystrons!

30. ¡ MUCHAS GRACIAS !

31. EXTRA

32. Typical beam spot at the output of the linac
<1mm
<1mm
<1mm