1. A Design of a Gantry with Superconducting Magnets for 350 MeV Protons
Presented at: ECPM, May 12, 2012 by:
Mattia Schaer, Tony Lomax, Marco Schippers
Vladimir Anferov, Niek Schreuder

2. OUTLINE Motivation optics design of a 350 MeV SC gantry
What does it bring?

3. New Applications for E = 350 MeV
SHARPER DOSE DISTRIBUTION IN TREATMENTS
PROTON RADIOGRAPHY
Range verification by in-vivo by direct measurements with protons
Treatment of small lesions (stereo tactic trmt)
Sharpen edge of dose distrib.
ECPM 2012, EUCARD2 GANTRY Workshop
PSI Daresbury,

4. Existing 235 MeV Gantry Design
E = 235 MeV, Bρ = 2.35 Tm
Patent pending
Licensed to ProNova Solutions, LLC
y-plane
x-plane
14 m
5 cm
SC sections
Input beam: x = y = 5.0 mm , x’ = y’ = 2.4 mrad
δ = 0%
d_isoc
SCAN
2 SC achromats
< 4 T in SC-B, < 1.6 T in SC-Q
SC-Q: ~ 40 T/m
60 deg – 150 deg bends
small dispersion
Waist-to-waist imaging
Weight: ~ 12 tons
Dimensions:
Radius = 4.3 m
Length = 6.7 m
d_isoc = 3.0 m

5. Adapting to 350 MeV 235 MeV 350 MeV E = 350 MeV, Bρ = 2.94 Tm  + 25%
d_isoc
d_isoc
235 MeV
Gantry
350 MeV
Radius [m]
4.3
4.0
Length [m]
6.7
7.7
d_isoc [m]
3.0
2.5
25% Bρ increment but fields can not be increased  25% magnet length increase
ECPM 2012, EUCARD2 GANTRY Workshop
PSI Daresbury,

6. PSI-Optics for 350 MeV
y-plane
x-plane
14 m
5 cm
INBeam (2): x = y = 3.0 mm , x’ = y’ = 7.0 mr
δ = 0%
δ = 3%
SCAN
350 MeV
25% Bρ increment by increase of magnet length
PSI optics:
Point-to-point imaging
1 “normal“ quadrupole less
Positive pole face rotations
Large emittance and momentum acceptance:
ε = 21π mm.mrad and δ = ± 3%

7. Large Momentum Acceptance
Optics characterized by
δ = Δp/p0 = ± 3 %
Enabling new techniques:
SCENARIO 1: Static delivery of SOBP
SCENARIO 2: Energy changes “on-the-fly” ( PSIspec:100ms/% )
SCENARIO 3: Transport of the beam delivered by a booster
CONVENTIONAL USE
E < 250 MeV
B = T
HIGH E USE
E = 350 MeV
B = 4 T

8. New Solutions for E < 250 MeV
Static Delivery of SOBP
R(E)= cm
p0-δ
p0+δ p0
SOBP generated by protons with momentum between p0-3% and p0+3% can be delivered without magnetic field changes
Energy modulation:
either at the beginning in the degrader
or at the coupling point with a ridge filter
E [MeV]
Range cm]
R [cm] for +/- 3% p/p
100
7.8
1.6
150
15.9
3.0
250
38.0
7.0
ECPM 2012, EUCARD2 GANTRY Workshop
PSI Daresbury,

9. Stability / Sensitivity Tests
Errors in quads field in Achromat 1
y-plane
x-plane
5 cm
1 % err
5 % err
STABILITY REQUIREMENTS:
Beam position ± 1.0 mm
Beam size: ± 1.0 mm
Errors in quads field in Achromat 2
1 % err
5 % err
y-plane
x-plane
5 cm
Max allowed field errors ≤ 1 %
Graphs:
Bends are slower than Achr.Quads
ECPM 2012, EUCARD2 GANTRY Workshop
PSI Daresbury,

10. Conclusion (1) APPLICATIONS: Proton radiography at all sites
Better (sharper) dose distribution achievable
RESULTS of this STUDY :
Feasible
350 MeV gantry has same size as 235 MeV gantry
Changes in optics: point-to-point imaging
1 Qpole less

11. Conclusion (2) GENERAL CONCLUSION ON SC GANTRY:
Not much smaller in diameter. R mostly determined by scan angle (dist scan-isoc = 2 m) + SC magnet width
Much smaller weight
New beam optics possible  large acceptance
OPEN QUESTIONS:
Higher order beam optics (static and dynamic field maps)
How fast can the magnets change their field ?
Practical cooling issues

12. THANKS…
DREAMING ABOUT
NEW POSSIBILITIES …