The Particle Therapy Cancer Research Institute is a member of the 4 th April 2013, PASI Workshop,...

The Particle Therapy Cancer Research Institute is a member of the

4th April 2013, PASI Workshop, RAL

Ken PeachJohn Adams Institute for Accelerator Science

&Particle Therapy Cancer Research institute

University of Oxford

PAMELA Follow up?

http://www.ptcri.ox.ac.uk/


PAMELA & related ideas, University of Huddersfield 12th April 2013 2 Ken Peach, JAI & PTCRi, Oxford

Outline• The PAMELA conceptual design• Limitations and challenges• Summary



100

80

60

40

20

50 100 150

Depth (mm)

Dos

e (%

)

Depth Dose curves – x-rays & electrons

MV x-rays

20MV electron

60Co x-rays

200kV x-rays



100

80

60

40

20

50 100 150

SOBP

Pristine peak

Depth (mm)

Dos

e (%

)

tumour

Depth Dose curves – photon and proton

MV x-rays



Photons, Protons and Carbon

0

1

2

3

4

5

6

7

8

9

10

0 2 4 6 8 10 12 14

Depth in water [cm]]

effe

ctiv

e do

se [

rela

tive

units

]

photons

protons

biol. eff. dose: Carbon ions

Tumor

0

1

2

3

4

5

6

7

8

9

10

0 2 4 6 8 10 12 14

Depth in water [cm]]

effe

ctiv

e do

se [

rela

tive

units

]

photons

protons

biol. eff. dose: Carbon ions

Tumor



Parameters



FFAG’S



EMMAThe World’s First non-Scaling FFAG

S Machida et al



EMMA lattice

After Rob Edgecock



PAMELA



• Issues– Injection &

extraction– Acceleration– Alignment

EMMA-like ns-FFAG machineKeil, Sessler & Trbojevic



From EMMA to PAMELA

The EMMA lattice

• Doublet structure– Focus and Defocus

• Dense lattice– Little space between

magnets• Lots of RF Acceleration

– Almost every other cell

From EMMA to PAMELA

FD

FD

F

The PAMELA lattice

• Triplet structure– Focus, Defocus, Focus

• Less Dense lattice– Long straight sections

• Less of RF Acceleration– Larger cavities– Lower frequencies

• Larger radius

Ken Peach (PTCRi, Oxford) Physics, Accelerators and Cancer 12

From Doublet to Triplet



THE PAMELA CONCEPTUAL DESIGN



Overview

Carbon source & injection

Proton source & injection

Carbon ring

Transfer line

Extraction

~12m

Proton ring



C

From scaling to PAMELA



Scaling restoration

ScalingRectangularRectangular& parallel



Final Cell Tunes



Stability Regions



PAMELA Layout



PAMELA: ring overview

Ring #1 (p, c) Ring #2 (c)

Energy 30~250MeV (p)8~68MeV/u (c)

68~400MeV/u

# of Cell 12 12

Diameter 12.5m 18.4m

K-value 38 41

Orbit excursion 18cm 21cm

Rev. freq 1.94~4.62MHz(p)0.98~2.69MHz(c)

1.92~3.91MHz

Magnet Triplet(FDF), SC Triplet(FDF), SC

length 57cm 113cm

aperture 25cm 33cm

Long Drift 1.3m 1.2m

Packing factor 0.48 0.65

Inj./Ext 1turn inj/ext2 LD (each)

1turn inj/ext2 LD (each

RF Max 8 LD Max 8 LD

Stable betatron tune ∆<0.1 Long straight section (~1.3m) Small beam excursion(<20cm) Strong field (max 3.5T)

SC magnet High repetition rate(~1kHz) is a big

challenge

Carbon ring

Proron ring

Injector(p): cyclotron

Injector(c): RFQ+LINAC

B

B0

r

r0

k

B

B0

r

r0

k

B

B0

1 kxr0

k(k 1)

2!

xr0

2

...

scaling PAMELA



Acceleration



Details – Ring Magnet



Double-Helix Principle

)cos(tan

:

)cos(:

)sin(:

0

0

0

nnR

J

Jzz

RJ

Jyy

RJ

Jxx

)cos(

)tan(

)cos(

)sin(

0

0

0

nnR

J

Jz

RJ

Jy

RJ

Jx

Current density:

Helix 1 Helix 2

)cos(

0

0

nconstJz

Jy

Jx

Double-helix coil: Smart way of creating a cosine-theta magnetMain advantage for PAMELA: No coil end problem

+

Double-Helix



High field quality

Patent GB 0920299.5



Kicker Magnets



Septum Magnets



Ring-to-Ring transfer line



Ion sources

Carbon RFQ Parameters

E-field frequency 200MHzEI 8 keV/uEf 382 keV/uTransmission 75%RFQ length 2.4mElectrode potential 80 kV



FFAG Beam Transport

D F F D0.2m 0.2m

3.6m

5m

𝑩𝒚 (𝒓 ,𝜽 )=𝑩𝒚 .𝟎( 𝒓𝒓 𝟎)𝒌

𝑭 (𝜽 )

𝑛=( 𝜌𝐵𝑦

) 𝑑𝐵𝑦

𝑑𝑥, 𝜌 𝑖𝑠𝑟𝑎𝑑𝑖𝑢𝑠𝑜𝑓 𝑐𝑢𝑟𝑣𝑎𝑡𝑢𝑟𝑒

𝑩𝒚 (𝒙 ,𝒛 )=𝑩𝒚 .𝟎(𝒏𝝆 )𝒌

𝑭 (𝒛 )𝑩𝒚 (𝒙 ,𝒛 )=𝑩𝒚 .𝟎( (𝒙+𝒙𝟎 )𝒙𝟎

)𝒌

𝑭 (𝒛 )



Beam Transport

Horizontal

Vertical



Gantry Design



PAMELA

STRENGTHS & WEAKNESSES

What to do next (if possible)



Injection

Winkelmann et al. Rev. Sci. Instrum. 79, 02A331 2008



• Generic problem– Non-relativistic to relativistic transition

• Isochronous – large aperture magnets?• Variable frequency – typically factor 3

• Ideally would like a HV capacitor

– Induction cavity?– Solid State?

RF

beam



Is there a mapping from circular to elliptical?

Probably not for pure dipole …but for multipole?

Magnets



Elliptical Double-Helix?

+ +

𝑑𝐵 (𝑥 )= 𝜇 𝐼2𝜋

𝑑 (cos𝜃 )

√𝑟 2+𝑥2−2𝑟𝑥 cos𝜃

xrq

√𝑟2+𝑥2−2𝑟𝑥 cos𝜃

𝐵 (𝑥 )= 𝜇 𝐼2𝜋𝑟

xrq

√ 𝑎2𝑏2

(𝑎2−𝑏2 ) cos2𝜃+𝑏2+𝑥2−2

𝑎𝑏

√ (𝑎2−𝑏2 ) cos2𝜃+𝑏2𝑥 cos𝜃

𝑑𝐵 (𝑥 )= 𝜇 𝐼2𝜋

𝐼 (𝜃 )𝑑 ( cos𝜃 )

√ 𝑎2𝑏2

(𝑎2−𝑏2 ) cos2𝜃+𝑏2+𝑥2−2

𝑎𝑏

√ (𝑎2−𝑏2 ) cos2𝜃+𝑏2𝑥cos𝜃

∄ 𝑰 (𝜽 ) s . t .𝑩 (𝒙 ) is independent of 𝒙

?

I think that

Is this a theorem?



• Two rings– Ugly– Expensive

• Can it be done with one ring?– Magnets – at the limit

• Constraints– Low packing factor a

» Magnetic length/total length» Constrained by magnetic field strength

– Small number of cells» Orbit excursion 1/(number of cells)

» Constrained by magnetic field strength

Lattice?



NEW LATTICE IDEAS?

From Ring to Racetrack?



Lattice - racetrack

DF F

DF F

DF

F

DF

F

DF

F

DF

F

DF

F

DF

F

DF

F

DF

F

DF

F

DF

F



Lattice - racetrack

DF

F

DF

F

DF

F

DF

FD

FF

DF

F

DF

F

DF

F

PAMELA ArcsPAMELA Arcs

FFA

G B

eam Tran

spo

rt

Mat

chin

g

Match

ing

Mat

chin

gM

atchin

gInjection/extraction

RF

DF

F

DF

F



Arc Lattice

DF F

DF

F

DF F

DF

F

DF

F

DF

F

DF

F

DF F

DF

F

DF

F

DF

F

DF

F

DF

FD FF D F

F

DF

F

DF

FD

FF

DF

F

DF F• Increase a?

Larger Dp/p?

but low a preferred



Arc Lattice

DF

F

DF

F

DF

F

DF

F

DF

F

DF

F

DF

F

D

D

D

D

D

D

FD

FD• Triplet or doublet?

– EMMA-like cell?

Matching from FDF or DF to DFFD

(or FDDF)?

but alignment sensitivity



• Assume – 6m straight sections– 24m arcs

• 60m circumference

• b at injection/extraction– 0.25/0.61 (proton)– 0.13/0.73 (carbon)

• revolution frequency @ injection/extraction– 1.25 MHz / 3.1 MHz (proton)– 0.65 MHz / 3.5 MHz (carbon)

• RF duty factor > 81% multi-bunch

RF



Gantry with a range of settings in the 90 bend– i.e. set once per patient?– Very energy then x & y?

Energy the fastest variable

“Banana shaped” trajectories through the tumour– “only software” …

orFast sweeping magnets to compensate

Gantry Development?

Iso-centreSection 1

Section 2Section 3

Section 4

1 mA

B

C

C

Beam Shaping

and Scanning

FFAG Transport



• PAMELA Conceptual Design– “Proof of Principle”

on paper– Main weaknesses

ion source (can be fixed … known technology) RF (common problem for low E ions) Gantry (sketch solution, but needs work) Lattice (two rings – expensive, esp. carbon)

– Possible new lattice “Racetrack” configuration

matching from arcs to long straights?

alignment sensitivity?

orbit excursion?

• Anyone interested in leading?

Summary


The Particle Therapy Cancer Research Institute is a member of the 4 th April 2013, PASI Workshop,...

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