introduction to accelerator physics · 24.07.2017 1 introduction to accelerator physics part 1...
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24.07.2017
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Introduction to Accelerator PhysicsPart 1
Pedro Castro / Accelerator Physics Group (MPY)Introduction to Accelerator PhysicsDESY, 24th July 2017
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 2
DESY CERN
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Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 3
Applications of accelerators
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Applications of Accelerators (1)
Particle colliders for High Energy Physics (HEP) experiments
Fixed target experiments
Two beams collider experiments
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Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 5
Applications of Accelerators (1)
Particle colliders for High Energy Physics experiments
Example: the Large Hadron Collider (LHC) at CERN
superconducting magnets(inside a cryostat)
built between 2001 and 2009Higgs discovery: July 2012
8.6 km
Mont BlancLake Geneva Geneva
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> About 120 accelerators for research in “nuclear and particle physics”
Worldwide …
http://en.wikipedia.org/wiki/List_of_accelerators_in_particle_physics
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Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 7
Applications of Accelerators (2)
Light sources for biology, physics, chemistry… experiments
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 8
Applications of Accelerators (2)
B
Light sources for biology, physics, chemistry… experiments
Electromagnet
• structural analysis of crystalline materials• X-ray crystallography (of proteins)• X-ray microscopy• X-ray absorption (or emission) spectroscopy• …
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Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 9
7 GeV
Example: Positron-Elektron-Tandem-Ring-Anlage (PETRA)‘positron-electron tandem ring accelerator’ at DESY
built between 1976 and 1978HEP experiments: 1978-1986
JADE CELLO,PLUTO
TASSOMARK J
0.5 GeVe-/e+
e+e- collisionsat 2 x 19 GeV
gluon discovery: 1979
2.3 km long
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 10
7 GeV
Example: Positron-Elektron-Tandem-Ring-Anlage (PETRA)‘positron-electron tandem ring accelerator’ at DESY
built between 1976 and 1978HEP experiments: 1978-1986gluon discovery: 1979
40 GeVprotons
12 GeVe-/e+
HERA
protons
pre-accelerator for HERA 1987-2007synchrotron radiation since 1987
0.5 GeVe-/e+2.3 km long
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Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 11
Example: Positron-Elektron-Tandem-Ring-Anlage (PETRA)‘positron-electron tandem ring accelerator’ at DESY
e-/e+
built between 1976 and 1978HEP experiments: 1978-1986gluon discovery: 1979
pre-accelerator for HERA 1987-2007synchrotron radiation since 1987PETRA III since 2009
Max von Laue hall300 m
2.3 km long
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 12
e-
e-
photons
14 beamlines30 exp. stations
Max von Laue hall
http://photon-science.desy.de/facilities/petra_iii/beamlines/index_eng.html
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Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 13
Example: Positron-Elektron-Tandem-Ring-Anlage (PETRA)‘positron-electron tandem ring accelerator’ at DESY
pre-accelerator for HERA 1987-2007synchrotron radiation since 1987PETRA III since 2009PETRA III Extension from 2014
e-/e+
built between 1976 and 1978HEP experiments: 1978-1986gluon discovery: 1979
2.3 km long
hall nord
hall east
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 14
> About 120 accelerators for research in “nuclear and particle physics”
> About 70 electron storage rings and electron linear accelerators used as light sources (so-called ‘synchrotron radiation sources’)
Worldwide …
http://en.wikipedia.org/wiki/List_of_synchrotron_radiation_facilities
http://en.wikipedia.org/wiki/List_of_accelerators_in_particle_physics
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Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 15
For radioisotope production
Applications of Accelerators (3)
For radiotherapy and radiosurgery:• x-rays and gamma-rays
• ions (from protons to atoms with atomic number up to 18, Argon)
• neutrons
proton beam + stable isotopetransmutation
radioactive isotope
Accelerators in medicine
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 16
For example:
Applications of Accelerators (3)
18 MeV proton acceleratorcyclotron
Accelerators in medicine
For radioisotope production
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Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 17
For example: p
Oxygen-18 + positron
97% of decays
Applications of Accelerators (3)
18 MeV proton accelerator Oxygen-18 (stable)target
Fluorine-18 (half-life time = 110 min.)
(transmutation)
Accelerators in medicine
For radioisotope production
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For example: p
Fluorine-18 (half-life time = 110 min.)
Applications of Accelerators (3)
18 MeV proton accelerator Oxygen-18target
Fludeoxyglucose (18F)
(transmutation)
Accelerators in medicine
For radioisotope production
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Positron EmissionTomography (PET)
Applications of Accelerators (3)
detectors
!
!
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 20
PET
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Positron EmissionTomography (PET)
Applications of Accelerators (3)
detectors
!
!
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 22
> About 120 accelerators for research in “nuclear and particle physics”
> About 70 electron storage rings and electron linear accelerators used as light sources (so-called ‘synchrotron radiation sources’)
Worldwide …
> More than 7,000 accelerators for medicineradiotherapy (>7,500), radioisotope production (200)
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Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 23
For industrial applications:
Applications of Accelerators (4)
approx. numbers from 2007 (worldwide)
ApplicationIon implantation ~ 9500Electron cutting and welding ~ 4500Electron beam and x-ray irradiators ~ 2000Ion beam analysis (including AMS) ~ 200Radioisotope production (including PET) ~ 900Nondestructive testing (including security) ~ 650Neutron generators (including sealed tubes) ~ 1000
with energies up to 15 MeV
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 24
For industrial applications:an example: electron beam welding
‘deep welding effect’
up to 15 cm
acceleration up to 60-200 keV
Applications of Accelerators (4)
magnets as‘focusing lenses’as well as‘deflectors’
electron beam
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Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 25
> About 120 accelerators for research in “nuclear and particle physics”
> About 70 electron storage rings and electron linear accelerators used as light sources (so-called ‘synchrotron radiation sources’)
> More than 7,000 accelerators for medicineradiotherapy (>7,500), radioisotope production (200)
ion implantation (>9,000) , electron cutting and welding (>4,000) …> More than 18,000 industrial accelerators
Worldwide …
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 26
> About 120 accelerators for research in “nuclear and particle physics”
> About 70 electron storage rings and electron linear accelerators used as light sources (so-called ‘synchrotron radiation sources’)
> More than 7,000 accelerators for medicineradiotherapy (>7,500), radioisotope production (200)
ion implantation (>9,000) , electron cutting and welding (>4,000) …> More than 18,000 industrial accelerators
< 1%
Worldwide …
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Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 27
> About 120 accelerators for research in “nuclear and particle physics”
> About 70 electron storage rings and electron linear accelerators used as light sources (so-called ‘synchrotron radiation sources’)
> More than 7,000 accelerators for medicine
> More than 18,000 industrial acceleratorsion implantation (>9,000) , electron cutting and welding (>4,000) …
radiotherapy (>7,500), radioisotope production (200)
Worldwide …
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 28
Many millions of television sets, oscilloscopes using CRTs (Cathode Ray Tube)
Applications of Accelerators (5)
TV
oscilloscope
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Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 29
Many millions of television sets, oscilloscopes using CRTs (Cathode Ray Tube)
Applications of Accelerators (5)
acceleration
magnets as ‘focusing lenses’as well as ‘deflectors’
25 frames / s
625lines
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 30
Applications of Accelerators (6)
X-ray tubesDC high voltage (20-150 kV)
VACUUM
braking radiationor bremsstrahlung
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Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 31
Working with accelerators in the control room …
…requires:
- a lot of (accelerator) physics knowledge
- a lot of (accelerator) engineering knowledge
- some Sherlock Holmes’ skills
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 32
The case begins…
Accelerator Control RoomHamburg, DESYSat. 12th June 20102 o’clock a.m.PETRA runs with a beam
current of 75 mA
02:24 a.m.: beam lost
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Circular accelerators: the synchrotron
vacuum chamberbending magnet
accelerating device
injector
straight sectionsbeam
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 34
Dipole magnet
beam
! dipole magnets: tomorrow
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Circular accelerators: the synchrotron
vacuum chamberbending magnet
accelerating device
injector
straight sections
! radiofrequency acceleration: tomorrow
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 36
Low Energy Antiproton Ring (LEAR) at CERN (built in 1982)
Circular accelerators: the synchrotron
vacuum chamber
accelerating device
bending magnet
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B (perpendicular)
R
Circular accelerators: the synchrotron
charge velocity
of the particle
magnetic field
momentum
"# $ %&#%' $ ()# * +
+ , )# → " $ ()+
(circular motion) "# , )# → " $ /)0
1(+ $ /)
1 → 1 $ /)(+
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 38
vacuum chambermagnet
accelerating device
injector
straight sections
Circular accelerators: the synchrotron
(circular motion)
+ , )# → " $ ()+
"# , )# → " $ /)0
1(+ $ /)
1 → 1 $ /)(+ $ 2345'64'
! increase B synchronouslywith & $ /) of particle
1
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Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 39
DESY (Deutsches Elektronen Synchrotron)
DESY: German electron synchrotron
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 40
DESY (Deutsches Elektronen Synchrotron)
DESY: German electron synchrotron, 1964, 7.4 GeV
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The Main Accelerator Control Room
beam current [mA]
time
Hamburg, DESYSat. 12th June 2010
02:24 a.m.: beam lost
02:24 a.m.: beam lost
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 42
PETRA runs with beam around the clock
17th July 2015 16:45
[mA]
building 25f, HASYLAB
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PETRA runs with beam around the clock
17th July 2015 16:45
[mA]
24 hours
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 44
An example of PETRA running with ‘top-up’ modus on/off
7~1.3hours
top-up modus
21st July 2015 09:35 - 11:15
beam current [mA]
time
beam lifetime
< $ <=>? !
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γγγγbremsstrahlung
scattering with the Coulomb field of a gas atom→ the electron is deflected and lost inthe surrounding vacuum chamber
-
E > 6 GeVE < 6 GeV
electrons can gain or loose energy→ called Touchek effect→ depends on the density of the electronbunch
large energy loss that leads to particle loss
bunch
Beam lifetime
rest gasscattering
Coulomb scatteringbetween two electronsfrom the same bunch
The lifetime of an electron beam is mainly limited by two effects:
-
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 46
An example of PETRA running with ‘top-up’ modus on/off
7~1.3hours
top-up modus
21st July 2015 09:35 - 11:15
beam current [mA]
time
beam lifetime
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electrons injected in PETRA
‘top-up’ modus
~0.9 mA = 1%
beam current [mA]
time
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 48
What are the advantages of running in ‘top-up’ modus?
• stable intensity conditions for measurements• constant heat load on optical components (mirrors, filters, crystals…)
" stable photon beam angle and position (‘pointing stability’)" stable wavelength
• constant heat load on accelerator vacuum chamber• increased stability of all systems• diagnostics: small dynamic range
‘top-up’ modus
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The Main Accelerator Control Room
beam current [mA]
time
Hamburg, DESYSat. 12th June 2010
02:24 a.m.: beam lost
02:24 a.m.: beam lost
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 50
Run number 4: 60 Bunches; 23rd – 30th March, 2011
magnetpower supply
power off incrate at DORIS
RF??
top-uptiming problems
RF??beam losswithout dump
RF problemsand longitudinalinstabilities
vertical beam blow up
RF circulatorwater cooling
RF??
RF circulatorwater cooling
One example of PETRA run over 7 days
Source: K. Balewski (MAC report 2011)
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http://ttfinfo.desy.de/petra/show.jsp?dir=/2010/23/11.06_n&pos=2010-06-12T02:26:30
The link to the electronic logbook:
Beam lost at 02:24 a.m.
What to do?
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 52
The Machine Protection System status from 12th June 2010 at 02:26
12th June 2010 02:26
The first suspect released: MPS is not guilty
• vacuum system ok• magnet system ok• radio-frequency ok• water cooling ok…“all systems up and running”
• vacuum system ok• magnet system ok• radio-frequency ok• water cooling ok…“all systems up and running”
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Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 53
Electrons can be injected but cannot be stored !
beam current at injectionbeam current after a few turns
injection problemoraperture problem?
beamcurrent
time
500 µs ≈ 65 turns
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 54
Next suspect: injection
stored beam reference trajectory
vacuum chamber
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Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 55
Next suspect: injection
injected beam
stored beam
bending magnet
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 56
Next suspect: injection
dipoledipoledipole
stored beam
septumhomogeneus fieldfree field region
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Next suspect: injection + accumulation
dipoledipoledipole
stored beam
septuminjected beam
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 58
Next suspect: injection + accumulation
dipoledipoledipole
stored beam
septuminjected beam
PETRAseptum
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Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 59
septum at the Proton Synchrotron Booster (PSB) at CERN
homogeneus fieldfree field region
beaminjected beamstored beam
Next suspect: injection + accumulation
(1)
(2)
(3)
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 60
stored beam
septum
kicker(very fast dipole)
kicker(very fast dipole)
kicker(very fast dipole)
injected beam
time
kickerfield
~20 µs
Next suspect: injection + accumulation
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Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 61
Electrons can be injected but cannot be stored !
beam current at injectionbeam current after a few turns
injection problemoraperture problem?
beamcurrent
time
500 µs ≈ 65 turns
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 62
Next suspect: an aperture problem
Hamburg, DESYSat. 12th June 2010
02:24 a.m.: beam lost07:00 a.m.: visual inspection
in accelerator
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Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 63
Next suspect: the new octant in ‘Max von Laue hall’
e-
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 64
e-
Next suspect: the new octant in ‘Max von Laue hall’
e-beam
22.5 m
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Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 65
Undulator PU 10
undulator field lines
Next suspect: the new octant in ‘Max von Laue hall’
Hamburg, DESYSat. 12th June 2010
02:24 a.m.: beam lost07:00 a.m.: visual inspection
in new octant
+NS
NS
permanentmagnets
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 66
Undulator PU 10
Next suspect: the new octant in ‘Max von Laue hall’
Hamburg, DESYSat. 12th June 2010
02:24 a.m.: beam lost07:00 a.m.: visual inspection
in new octant
electrons
photons
undulator
undulator field lines
beam+N
S
NS
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Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 67
Undulator PU 10
very flat undulator vacuum chambers
undulator field lines
7 mm
9 mm
Next suspect: the new octant in ‘Max von Laue hall’
Hamburg, DESYSat. 12th June 2010
02:24 a.m.: beam lost07:00 a.m.: visual inspection
in new octant
beam+N
S
NS
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 68
a couple of months earlier…
vacuum chamber
Next suspect: the new octant in ‘Max von Laue hall’
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citation from the logbook: “What we have tried so far: …”
citation from the logbook: “Visual inspection of new octant: no findings”
timeof entries
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 70
Hamburg, DESYSat. 12th June 2010
02:24 a.m.: beam lost07:00 a.m.: visual inspection
in new octant11:52 a.m.: start aperture scan
Next suspect: an aperture problem
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Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 71
Need of focusing
beam / bunch
vacuum chambermagnet
accelerating device
injector
straight sections
pr
beam
we need to focus the beam !
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 72
Quadrupole magnets
quadrupole magnet:
B
beam
beam
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Quadrupole magnets
quadrupole magnet:four iron pole shoes of hyperbolic contour
hyperbola
x
y
xgBy ⋅−=
ygBx ⋅=
)gradient quadrupole ( 20
RIg µ
=
RB
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 74
Quadrupole magnets
xgFxgB xy ⋅−=⇒⋅−=
x
y
B
"# "#
"# $ ()# * + (Lorentz force)
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Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 75
Classical mechanics: harmonic oscillator
restoring force:
" $ $%&
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 76
Quadrupole magnets
xgFxgB xy ⋅−=⇒⋅−=
ygFygB yx ⋅=⇒⋅=
focusing !
defocusing
x
y
B "'
"'
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Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 77
In light optics…
defocusinglens
focusinglens
light rays
1(∗ $ 1
(*+ 1
(,$ %
(*(,
(: focal length
(light optics)(∗: systemfocal length
1(∗ $ %
(0 . 0if (* $ $(, $ (
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 78
Quadrupole magnets
QD + QF = net focusing effect:
charged particle
defocusingquadrupole(rotated 90°)
focusingquadrupole
center of quadrupoles
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Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 79
Quadrupole magnets
B B
N
N
S
S
I
I
II
vertical defocusinghorizontal focusing
vertical focusinghorizontal defocusing
rotated 90°I = -I
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 80
Quadrupole magnets
QD + QF = net focusing effect:
focusingquadrupole
defocusingquadrupole
beam
y-plane:
defocusingquadrupole
focusingquadrupole
beam
x-plane:
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Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 81
Quadrupole magnets
QD + QF = net focusing effect:
defocusingquadrupole
focusingquadrupole
beam
x-plane:
defocusingquadrupole
focusingquadrupole
QF QD QF QD QF QD QF QD QF QD
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 82
Circular accelerator
cell
dipolemagnet
dipolemagnet
defocusingquadrupole
focusingquadrupole
focusingquadrupole
beam
PETRA
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Circular accelerator
cell
dipolemagnet
dipolemagnet
defocusingquadrupole
focusingquadrupole
focusingquadrupole
beam
corrector dipole
corrector dipole
corrector dipole
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 84
Hamburg, DESYSat. 12th June 2010
02:24 a.m.: beam lost07:00 a.m.: visual inspection
in new octant11:52 a.m.: start aperture scan
defocusingquadrupole
focusingquadrupole
QF QD QF QD QF QD QF QD QF QD
beam
Next suspect: an aperture problem
corrector dipole 184 hor. corrector dipoles194 ver. corrector dipoles
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Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 85
First useful hint: aperture problem
Beam position monitor
Hamburg, DESYSat. 12th June 2010
02:24 a.m.: beam lost07:00 a.m.: visual inspection
in new octant11:52 a.m.: start aperture scan13:20 a.m.: beam stored
244 beam position monitors
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 86
First useful hint: aperture problem
horizontalbeam pos.[mm]
verticalbeam pos.[mm]
N
S
EW
NENW
SESW
W N E S
Hamburg, DESYSat. 12th June 2010
02:24 a.m.: beam lost07:00 a.m.: visual inspection
in new octant11:52 a.m.: start aperture scan13:20 a.m.: beam stored
2.3 km
244 monitors
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Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 87
First useful hint: horizontal aperture problem
horizontalbeam pos.[mm]
verticalbeam pos.[mm]
N
S
EW
NENW
SESW
W N E S
Hamburg, DESYSat. 12th June 2010
02:24 a.m.: beam lost07:00 a.m.: visual inspection
in new octant11:52 a.m.: start aperture scan13:20 a.m.: beam stored
244 monitors
radiofrequencysystems
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 88
First useful hint: horizontal aperture problem
N
S
EW
NENW
SESW
Hamburg, DESYSat. 12th June 2010
02:24 a.m.: beam lost07:00 a.m.: visual inspection
in new octant11:52 a.m.: start aperture scan13:20 a.m.: beam stored
defocusingquadrupole
focusingquadrupole
QF QD QF QD QF QD QF QD QF QD
beam
corrector dipole
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Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 89
First useful hint: horizontal aperture problem
horizontalbeam pos.[mm]
N
S
EW
NENW
SESW
W N E S
new octant
Hamburg, DESYSat. 12th June 2010
02:24 a.m.: beam lost07:00 a.m.: visual inspection
in new octant11:52 a.m.: start aperture scan13:20 a.m.: beam stored
after‘flattening’the orbit
244 monitors
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 90
citation from the logbook: “the problem is at the end of the new octant”
horizontal aperture problem in the new octant
second hint: vacuum pressure raise in the new octant
beam current [mA] vacuum pressure [mb]
beam current
vacuum pressure
vacuum pressure
02:24 a.m.beam lost
aperture scan+ trajectory corrections
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Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 91
horizontal aperture problem in the new octant
second hint: vacuum pressure raise in the new octant
beam current [mA] vacuum pressure [mb]
beam current
vacuum pressure
vacuum pressure
02:24 a.m.
beam
60 m
PU13 PU14
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 92
endoscope
visual inspection inside the vacuum chamber…
beam
PU13 PU14
beam
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Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 93
endoscope
visual inspection inside the vacuum chamber…
beam
PU13 PU14
vacuumbellows
beam beam
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 94
visual inspection inside the vacuum chamber…
vacuumbellows
RF fingers
beam
beam
an example of vaccum bellows
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Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 95
the problem was found: RF fingers
beam
beam
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 96
electric field of a relativistic particle
e
) $ 00 $ 0
1
) $ 020 ≅ 1
1e
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Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 97
electric field of a relativistic particle
e
1
1 $ (445=
61 $ 0071 $ 00 sin0 ; </0>0
>#>
! $ 11 $ 00
) $ 02
1?e z
;cylindrical coordinates
) $ 00 $ 0
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 98
electric field of a relativistic particle
e
1
1 $ (445=
61 $ 0071 $ 00 sin0 ; </0>0
>#>
! $ 11 $ 00
) $ 02
1?e z
! $ 10 $ 0
1 $ (445=
1>0
>#>
;cylindrical coordinates
) $ 00 $ 0
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Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 99
electric field of a relativistic particle
e
! $ 10 $ 0
1
1 $ (445=
61 $ 0071 $ 00 sin0 ; </0>0
>#>
! $ 11 $ 00
1@ ; $ 0 $ (445=
1!0>0
>#>
1A ; $ 42 $ (
445= !>0
>#>
1 $ (445=
1>0
>#>
) $ 02
1?e z
;cylindrical coordinates
) $ 00 $ 0
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 100
electric field of a relativistic particle
e
1
1 $ (445=
61 $ 0071 $ 00 sin0 ; </0>0
>#>
! $ 11 $ 00
! ≫ 10 ≅ 1
1e
1@ ; $ 0 $ (445=
1!0>0
>#>
1A ; $ 42 $ (
445= !>0
>#>
! → ∞ 0
! → ∞ ∞
z
! $ 10 $ 0
1 $ (445=
1>0
>#>
) $ 020 ≅ 1
) $ 00 $ 0
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Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 101
RF fingers and wakefields
vacuum chamber wall
beam
+ +++ +
+ +++ +
mirror currents
1
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 102
RF fingers and wakefields
vacuum chamber wall
beam
+ +++ +
+ +++ +
mirror currents
RF fingers
beam
RF fingers
1
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Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 103
beam
RF fingers and wakefields
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RF fingers: improvements doneold RF fingers were tilted outwards by 2 degrees
new RF fingers have stronger tilt, more tension
new design withRF fingers outside
beam
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Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 105
Summing-up of this part
accelerator physicswakefields, RF shielding (RF fingers)
Touchek effect (limiting beam lifetime)
Circular accelerators: the synchrotron
basic components
dipole, quadrupole, undulator magnets, corrector dipolesinjection system (kickers and septum)
vacuum pumps, vacuum pressure monitorsbeam position monitors
basic conceptsin operation
top-up modusaperture scanstrajectory (orbit) corrections
‘collective effects’
rest gas scattering (limiting beam lifetime)
vacuum chambers, bellows
Pedro Castro | Introduction to Accelerator Physics | 24th July 2017 | Page 106
Thank you for your attention