http://www.adams-institute.ac.uk [email protected]
A new accelerator for advanced research
andcancer therapy
Ken PeachJohn Adams Institute for Accelerator Science
University of Oxford and Royal Holloway University of London
Princeton 11th October 2007
Ken Peach John Adams Institute 11 x 07 2
Outline
• Introduction (Accelerators & Particle Physics)
• The Neutrino Factory(Why? The Muon Acceleration Challenge)
• The ns-FFAG Accelerator(non-scaling Fixed-Field Alternating Gradient)
EMMA
• Charged Particle Therapy (CPT)(proton and light-ion cancer treatment)
PAMELA
• Summary
Ken Peach John Adams Institute 11 x 07 3
Introduction
• There are more than 17,000 particle accelerators (> a few MeV) worldwide– Most are used in medicine
• Linacs, cyclotrons, some synchrotrons…
– Next most common in industry• Ion implantation etc
– Synchrotron Radiation Sources• Mostly synchrotrons, coming soon - linacs
– Neutron and radionuclide sources• Linacs, cyclotrons, synchrotrons, something weird
and– For particle physics!
• A few big synchrotrons (& colliders) – Often with Linacs at the front end
• And coming soon (maybe) the ILC
Ken Peach John Adams Institute 11 x 07 4
Classical Accelerator Types
Type Magnetic Field
RF Radius
Betatron Variable Fixed
Cyclotron Fixed Variable
Synchrotron Variable Fixed
FFAG Fixed ~Fixed
Linear acccelerators
(Linacs)
+ assorted others – electrostatic, RFQs etc …
+ new ideas (laser-plasma for example) …
Ken Peach John Adams Institute 11 x 07 5
The Bleeding Edge?
• Medical accelerators– Mainly linacs and cyclotrons
• Research accelerators– Mainly synchrotrons
• Particle Physics applications– Better synchrotrons (LHC)– Better linacs (ILC)
• Why do we need anything new?
– Because life presents new challenges!
Ken Peach John Adams Institute 11 x 07 6
HiggsHiggsBosonBosonHiggsHiggsBoson?Boson?
For
ceF
o rce
Car
rier
sC
arr i
ers
ZZ boson
WW boson
photon
ggluon
Generations of Generations of matter matter
-neutrino
tau
bbottom
ttop
III III
-neutrino
muon
sstrange
ccharm
II II
ee-neutrino
eelectron
ddown
upu
I I
Lep
tons
L
epto
ns
Qua
rks
Qua
rks
Particles and Forces
Each with its own
‘antiparticle’
© Brian Foster
Ken Peach John Adams Institute 11 x 07 7
The Standard ModelThe ParametersThe Parameters
• 6 quark masses– mu , mc, mt
– md, ms, mb
• 3 lepton masses– me, m, m
• 2 vector boson masses– Mw, MZ
• (m, mg=0)• 1 Higgs mass
– Mh
• 3 coupling constants– GF, , s
• 3 quark mixing angles– 12, 23, 13
• 1 quark phase–
http://www.adams-institute.ac.uk [email protected]
Neutrino Factory
The “ultimate” neutrino facility
Ken Peach John Adams Institute 11 x 07 9
The Standard ModelThe ParametersThe Parameters
• 6 quark masses– mu , mc, mt
– md, ms, mb
• 3 lepton masses– me, m, m
• 2 vector boson masses– Mw, MZ
• (m, mg=0)• 1 Higgs mass
– Mh
• 3 coupling constants– GF, , s
• 3 quark mixing angles– 12, 23, 13
• 1 quark phase–
Neutrino sector
Neutrino masses identically 0!!!!
Ken Peach John Adams Institute 11 x 07 10
i
i
ii
ii
i
i
i
i
i
MNS
e
e
ccescscseccsss
scesssccecsssc
escscc
e
ecs
sc
ces
esc
cs
sc
U
1
1
1
1
1
231312231312231223131223
231312231312231223131223
1313121312
1212
1212
1313
1313
2323
2323
Neutrino Mixing
Parameters of neutrino oscillation
1 absolute mass scale
2 squared mass diffs
3 mixing angles
1 phase
2 Majorana phasesβα,
)esinθ always ( δ
θθθ
ΔmΔm
m
iδ13
132312
223
212
νe
, ,
,
221
232
231
2i
2j
2ji
ΔmΔmΔm
mmΔm
solarAtmospheric Majorana3G
cij=cosij
sij=sinij
O(1eV) masses
unknown ,,
unknown
0.045 sin
0.62)-(0.34 2tan
eV10 9.1)-(7.0
2.2)-(0.49tan
eV10 2.98)-(1.9
232
132
122
25-221
232
2-3232
mSign
m
m
2
Ken Peach John Adams Institute 11 x 07 11
a =22 GFneE = 7.6 10-5 E
Where is the electron density ; is the density (g/cm3) ; E is the neutrino energy (GeV)
eP
ELm
ELm
ELmsssccc 4442313122312
213
221
231
232 sinsinsinsin8
ELmccsc 4
2223
212
212
213
221sin4
EaL
ELm
ELm
ELm sssc 4
213444
223
213
213 21sinsincos8
221
231
232
231
2213211
mas
E
Lmssc 422
23213
213
213sin4
ELm
ELm
ELmsssccsssc 4442313122312231312
213
221
231
232 sinsincoscos8
ELmsssccsssccsc 4
21323122312
223
213
212
223
212
212
213
221sincos24
Why is it hard to measure the parameters?
(Richter: hep-ph/0008222)
aa
cij=cosij, sij=sinij
Ken Peach John Adams Institute 11 x 07 12
What to Measure?
Neutrinos
e disappearance
e appearance
e appearance
disappearance
e appearance
appearance
… and the corresponding antineutrino interactions
Note: the beam requirements for these experiments are:
high intensity known flux
known spectrum known composition (preferably no background)
Ken Peach John Adams Institute 11 x 07 14
A Neutrino Factory is …
… an accelerator complex designed to produce >1020 muon decays per year directed at a detector thousands of km away
Muon Acceleration
… need to accelerate muons very quickly
[@5 GeV, ~0.1msec]
Ken Peach John Adams Institute 11 x 07 15
Neutrino Factory cost drivers
• High Power proton drivers – MW power, ns pulses
• RLA or FFAG?– Which is cheaper?
• RF – 30% of the cost?
• Cooling– How much? (20% of the
cost?)
BNL Feasibality Study 2
http://www.adams-institute.ac.uk [email protected]
The non-scaling FFAG Accelerator
Fixed-Field Alternating Gradient
Ken Peach John Adams Institute 11 x 07 17
Fixed Field Alternating Gradient accelerators
• Fixed-Field (like a cyclotron)
– Rapid acceleration possible– Rapid cycling possible
• Alternating Gradient (like a synchrotron)
– Focussing!!!!• Small(er) magnets/beam pipe/vacuum system
• … and large acceptance
• The best of both worlds!– So why is the world not full of FFAGs?
Type Magnetic Field RF Radius
FFAG Fixed ~Fixed
Ken Peach John Adams Institute 11 x 07 18
Early FFAGs (1955-1960)
• MURA built several electron FFAGs in the 1950s
20 to 400 keV machine
Chandrasekhar Bohr
Radial sector Spiral sector
Large complicated magnets• c.f. Cyclotron – large simple magnets
• c.f. Synchrotron – small simple magnets
Ken Peach John Adams Institute 11 x 07 19
Newer FFAG’s (post-2000)
• The Japanese have built two “proof of principle” proton FFAGs
500 keV proton FFAG @ KEK 150 MeV proton FFAG @ KEK
Ken Peach John Adams Institute 11 x 07 20
… but …
• Why?… the magnets are LARGE LARGE and COMPLICATEDCOMPLICATED
• Why does k have to be so large?1. Larger k means stronger focussing
2. k > 0 means horizontal focussing– This means that the average field increases with radius
3. The momentum compaction 1/(k+1)– Large momentum bite small orbit excursion p
pRR
Orbit excursion ~ 0.9m
+ k
r
rBB
00
where k >> 1
1 krp
Ken Peach John Adams Institute 11 x 07 21
Scaling and non-scaling FFAGs
k
r
rBB
00
where k >> 1
1 krp
k
r
rBB
00
where k = 1
LinearLinear magnets!
i.e. quadrupoles
Invented in 1999
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Simpler Magnets
… the magnets are LARGE LARGE and COMPLICATEDCOMPLICATED … to something SMALLSMALL and SIMPLESIMPLE
r
B (r)
Ken Peach John Adams Institute 11 x 07 23
The ns-FFAG
• Should combine the advantages of FFAGs – Fixed Field
• Fast cycling (limited essentially by RF)• Simpler, cheaper power supplies• No eddy-currents• High intensity (pulsed, ~continuous)• Low beam losses• Easier maintenance and operation• Lower stresses
– Strong Focussing• Magnetic ring• Variable energy extraction• Higher energies (than cyclotrons)• Different ion species possible
• with relative ease of construction
Ken Peach John Adams Institute 11 x 07 24
… so … where is the catch?
• Variable tune!
Tune ~ c
Must crossresonances
Ken Peach John Adams Institute 11 x 07 25
Beam Acceleration
• Resonance is a coherentcoherent effect– Can fast acceleration circumvent the
resonances?• If the momentum changes by a large
amount during a single turns, is it possible to leap-frog over the resonance?
– Small variation of the path length with momentum (small momentum compaction)
• Fixed radio-frequency cavities?
10MeV
20MeV
|df/f|~0.1%
0.1ns
Plots for EMMA
Ken Peach John Adams Institute 11 x 07 26
Does it work?
• We do not know!– There is no “no-go” theorem
• Need for a “proof of principle” demonstrator– EMMA
• Electron Model for Many Applications– Originally Electron Model for Muon Acceleration
• Funding obtained in the UK to design and build a EMMA – the world’s first non-scaling FFAG accelerator!
Ken Peach John Adams Institute 11 x 07 27
Objectives of the CONFORM Project
1. Show the non-Scaling Fixed-Field Alternating Gradient Accelerators work
• Build an Electron Model (EMMA)• Design a prototype Charged Particle
Therapy machine based on ns-FFAGs• Protons and carbon ions
2. Develop applications of ns-FFAGs
Ken Peach John Adams Institute 11 x 07 28
EMMA Parameters
42 identical straight length 394.481 mm
Long drift 210.000 mm
F Quad 58.782 mm
Short drift 50.000 mm
D Quad 75.699 mm
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EMMA at the ERLP@Daresbury
After Neil Bliss
ERLP Parameters
Ken Peach John Adams Institute 11 x 07 31
EMMA: Lattice & Magnets
B0 xB1
B0
xMagnet linear slide
After Neil Bliss
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Status of EMMA
• Funded! (~$10M)– Started 1st April 2007
• Lattice - fixed
• Component design - ongoing– Prototype quads being measured now
• Final design - complete Jan 08
• Construction - complete Jul 09
• Beam studies - until Sep 10– At least …
After Tkeichiro Yokoi
http://www.adams-institute.ac.uk [email protected]
PAMELA
Charged Particle Therapy (CPT)
BASROC & CONFORM
Ken Peach John Adams Institute 11 x 07 36
Incidence of Cancer in the UK
• 13.5% probability, all types (except skin cancer)– Around half are associated with specific risks– Statistically, some will be close to sensitive tissue
• and difficult to treat surgically or chemically
Source: Cancer Research UK
Ken Peach John Adams Institute 11 x 07 37
Why use protons?
After Bleddyn Jones
X-Rays100
80 80150
60
Protons
30050 50
60
0
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Why use 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
Daniela Schulz-Ertner, Heiddelberg
An important statisticAn important statistic
“ Radiotherapy remains a mainstay in the treatment of cancer. Comparison of the contribution towards cure by the major cancer treatment modalities shows that of those cured, 49% are cured by surgery, 40% by radiotherapy and 11% by chemotherapy”.
RCR document BFCO(03)3, (2003).
Chemotherapy provides by far the smallest contribution towards cancer cure yet is much more expensive than radiotherapy and generates a disproportionately large research and media interest.
Roger Dale, Hammersmith Hospital and Imperial College
What is RBE?RBE = Relative Biological Effectiveness.
A measure of the biological “potency” of a particular type of radiation relative to that of a reference radiation.
Reference radiation (conventional x-rays) has RBE = 1
For a given biological end-point:
Proton RBEs: ~ 1.1
Neutron RBEs: 3 - 5
Carbon ion RBEs: 3 - 5
radiationealternativwithrequiredDose
radiationreferencewithrequiredDoseRBE
Roger Dale, Hammersmith Hospital and Imperial College
The concept and definition of RBE are both straightforward. Unfortunately….
Even for a particular type of radiation, RBE is not fixed.
Its value depends on:
a) The size of the dose used at each treatment
b) The chosen biological end-point
c) The nature of the irradiated tissue
Roger Dale, Hammersmith Hospital and Imperial College
Ken Peach John Adams Institute 11 x 07 43
Hadron Therapy in Chiba (Japan)
Borrowed from Rob Edgecock
Ken Peach John Adams Institute 11 x 07 44
Cancer of the Kidney Stage I: TIa N0 M0 80GyE / 16fr. /4wks
Cancer of the Kidney Stage I: TIa N0 M0 80GyE / 16fr. /4wks
治療前
1 year1 year2 years2 years
3 years3 years4 years4 years
Monitoring and Control :Key issues for medical applications
time
Inte
gra
ted cu
rrent
Synchrotron & cyclotron
time
Inte
gra
ted cu
rrent
FFAG
Dose uniformity should be < ~2% To achieve the uniformity, precise intensity modulation is a must
Beam of FFAG is quantized. Active intensity control at the injection level and precise loss control are indispensable.
New approach to medical accelerator control is required in PAMELA (New postdoc is employed for the issue)
SOBP is formed by superposing Bragg peak
Gate width controls dose
Step size controls dose
intensity modulationintensity modulation
Takeichiro Yokoi
Ken Peach John Adams Institute 11 x 07 49
The requirements
• There are obvious potential benefits from proton/light ion therapy– Need to maximise the benefits
• Requirements– Rapid variable energy extraction– Rapid variable transverse spot scanning– Variable ion species– Accurate dose measurements
• Flux control
Ken Peach John Adams Institute 11 x 07 50
Synchrotron Cyclotron FFAG
Intensity (>100nA) Low Plenty Plenty
1-16nA >100nA
Maintenance Normal Hard Normal
Extraction eff Good Poor Good
Operation Not easy Easy Easy
Ions Yes No Yes
Variable energy Yes No Yes
Multi-extraction Possible No Yes
After Y.Mori KEK/Kyoto
Advantages of FFAG in Charged Particle Therapy
Ken Peach John Adams Institute 11 x 07 52
PAMELA
• Preliminary ideas– Cyclotron injection @ ~20 MeV (or 8 MeV – 2 ring)– 1 or 2 ns-FFAG proton rings
• 20 MeV 250 MeV (1 ring)• 8 MeV 31 MeV & 31 MeV 250 MeV (2 ring)
– + 1 Ion ring • 69 MeV/u 450 MeV/u
– (proton ring equivalent to 69 MeV/u Carbon)
Ken Peach John Adams Institute 11 x 07 53
Injection and Extraction
Small beam excursion of NS-FFAG makes energy variable beam extraction easier
Unique feature for fixed field accelerator However, large tune change requires phase adjustment mechanism in injection & extraction multi-kicker system
QD QD QDQF QF QF
Kicker#2Kicker#1 Septum∆p/p=+0.0
Circulating beam
@2nd kicker
@septumSeptum boundary
By changing the field strength and direction, beam position in
phase space can be adjusted Example of beam extraction (PAMELA)
Ken Peach John Adams Institute 11 x 07 54
Superconducting FFAG Gantries
Fixed field of 3.7T Transports 150-400 MeV/u
Length ~15m
D Trbojevic/BNL
Ken Peach John Adams Institute 11 x 07 56
Summary
• Non-scaling FFAG accelerators are:– New– Untried– Interesting for
• Neutrino physics• Cancer therapy
– And other applications » Spallation neutron sources, muon sources» Accelerator driven reactors, nuclear waste disposal
• We will know in ~3 years if they work– Let us hope that they do … they could be
very useful devices …