Download CERN and High Energy Physics

MAGNET TECHNOLOGY CENTRE
Accelerators, CERN and High Energy Physics
Pekka Suominen
European summer school on superconductivity 12.6.2008
MAGNET TECHNOLOGY CENTRE
Contents
Motivation for accelerators; nuclear physics, medical
and industrial applications
Principles of different types of particle accelerators
Superconducting components in accelerators (magnets,
RF-cavities)
Magnet systems of ion sources
CERN & LHC
Magnets systems of particle detectors
MAGNET TECHNOLOGY CENTRE
Accelerators – where?
CRT – Cathode Ray Tube
– (1) Electron accelerator (15 - 30 kV)
– (3) Focusing by (electro or permanent) solenoid magnets
– (4) Deflection by XY-magnets (eg. 100 Hz)
– (7) Phosphor layer with RGB zones
…
Soon to be replaced by LCD
© Wikipedia
MAGNET TECHNOLOGY CENTRE
Motivation for accelerators: nuclear physics
Studying the nucleus of the atom, their interactions, related forces and nuclear
models. Trying to understand
– the nature of nucleonic matter.
– the origin of the elements.
– events and the astrophysical sites that produce the elements.
MAGNET TECHNOLOGY CENTRE
Nuclear physics instrumentation
Detectors
Alpha
Beta
Gamma
MAGNET TECHNOLOGY CENTRE
Motivation for accelerators: particle physics
Also called high energy physics
Studies the elementary constituents of matter and radiation, and the
interactions between them
Standard Model: all particles except the Higgs boson have been
observed
motivation for LHC
© wikipedia:
1895 - X-rays produced by Wilhelm Röntgen (later identified as photons)[1]
1897 - Electron discovered by J. J. Thomson[2]
1899 - Alpha particle discovered by Ernest Rutherford in uranium radiation[3]
1900 - Gamma ray (high-energy photon) discovered by Paul Villard in uranium decay.[4]
1911 - Atomic nucleus identified by Ernest Rutherford, based on scattering observed by Hans
Geiger and Ernest Marsden.[5]
1919 - Proton discovered by Ernest Rutherford[6]
1932 - Neutron discovered by James Chadwick[7] (predicted by Rutherford in 1920[8])
1932 - Positron, the first antiparticle, discovered by Carl D. Anderson[9] (proposed by Paul Dirac
in 1927)
1937 - Muon discovered by Seth Neddermeyer, Carl Anderson, J.C. Street, and E.C. Stevenson,
using cloud chamber measurements of cosmic rays.[10] (It was mistaken for the pion until
1947.[11])
1947 - Pion discovered by Cecil Powell (predicted by Hideki Yukawa in 1935[12])
1947 - Kaon, the first strange particle, discovered by G.D. Rochester and C.C. Butler[13]
1955 - Antiproton discovered by Owen Chamberlain, Emilio Segrè, Clyde Wiegand, and
Thomas Ypsilantis
1956 - Neutrino detected by Frederick Reines and Clyde Cowan (proposed by
Wolfgang Pauli in 1931 to explain the apparent violation of energy
conservation in beta decay)
1962 - Muon neutrino shown to be distinct from electron neutrino by group headed
by Leon Lederman
1969 - Partons (internal constituents of hadrons) observed in deep inelastic
scattering experiments between protons and electrons at SLAC; this was
eventually associated with the quark model (predicted by Murray Gell-Mann
and George Zweig in 1963) and thus constitutes the discovery of the up quark,
down quark, and strange quark.
1974 - J/ψ particle discovered by groups headed by Burton Richter and Samuel
Ting, demonstrating the existence of the charm quark (proposed by Sheldon
Glashow, John Iliopoulos, and Luciano Maiani in 1970)
1975 - Tau lepton discovered by group headed by Martin Perl
1977 - Upsilon particle discovered at Fermilab, demonstrating the existence of the
bottom quark (proposed by Kobayashi and Maskawa in 1973)
1979 - Gluon observed indirectly in three jet events at DESY
1983 - W and Z bosons discovered by Carlo Rubbia, Simon van der Meer, and the
CERN UA-1 collaboration (predicted in detail by Sheldon Glashow, Abdus
Salam, and Steven Weinberg in the 1960s)
1995 - Top quark discovered at Fermilab[14][15]
2000 - Tau neutrino shown to be distinct from other neutrinos at Fermilab
MAGNET TECHNOLOGY CENTRE
Particle physics instrumentation
Very large setups (like Compact Muon Solenoid)
More details comes after…
MAGNET TECHNOLOGY CENTRE
Motivation for accelerators: medical applications
Electron emitter (gun)
Accelerator
Beam manipulation (focussing, bending, steering, …)
MAGNET TECHNOLOGY CENTRE
Medical applications – Hadron therapy
X-rays
Proton therapy
Carbon therapy
MAGNET TECHNOLOGY CENTRE
Motivation for accelerators: Industrial applications
Several fully automatic (turn-key) ion implantation systems available
Typical ion energies are in the range of 10 to 500 keV
Semiconductor device fabrication
– Used to alter the surface properties of semiconductor materials
– Doping
Metal finishing
– Tool steel toughening
– Surface finishing
MAGNET TECHNOLOGY CENTRE
Motivation for accelerators: Industrial applications
Electronics radiation-hardness tests
Simulation of space radiation environment
– Reliability of electronics in space
Heavy ion irradiation chamber and ion diagnostics.
© RADEF, Jyväskylä Finland
RADEF's proton station
MAGNET TECHNOLOGY CENTRE
Free Electron Laser (FEL)
Use accelerator & synchrotron radiation to create high power laser radiation
burg
Ham
,
Y
S
© DE
MAGNET TECHNOLOGY CENTRE
TESLA XFEL project
(DESY, Hamburg, Germany)
Users dream will soon become reality
Single shot imaging of single biomolecular complexes
– Needs many photons on the sample
© DESY, Hamburg
Time resolved studies of structural processes
during chemical and biological reactions
Ribosomes are large molecular complexes that act as "protein factories" and occur in every cell. The
X-ray laser opens up completely new opportunities to decipher such biological structures with atomic
resolution without the need for the extra step of tediously growing them into crystals first.
MAGNET TECHNOLOGY CENTRE
Accelerators in the world (2002)
(Old fashion CRT-televisions are not counted)
MAGNET TECHNOLOGY CENTRE
Principles of different types of particle
accelerators
How to accelerate?
- Use electric field on charged particle
(and magnets for steering & focusing)
MAGNET TECHNOLOGY CENTRE
High voltage generation
Wimhurst machine (~1880)
~10 kV
Van de Graaff generator
1929
Cockroft-Walton
voltage multiplier
Up to 1 MV
MAGNET TECHNOLOGY CENTRE
Linear accelerator (LINAC)
Principle of DC acceleration (static DC E-field)
– Intermediate electrodes are necessary for beam focusing (E-field shaping)
p+
700 kV
Ion source on
HV terminal
600 kV
500 kV
400 kV
300 kV
200 kV
100 kV
0 kV
Target on ground
potential
MAGNET TECHNOLOGY CENTRE
LINAC history
An idea to double the energy:
– Place ion source on
positive potential (+5 MV to ground)
Laboratory
– Laboratory with detectors sits on
negative potential (-5 MV to ground)
Not very convenient to work inside
HV-terminals…
Ion source
MAGNET TECHNOLOGY CENTRE
Linear accelerator
Ion source on High Voltage (HV) terminal
Few MegaVolts
Van de Graaff generator
Ion source
HV terminal
© BNL
MAGNET TECHNOLOGY CENTRE
Tandem linear accelerator
High Voltage (HV) terminal on center
ground potential
Injection and extraction on
Up to 20 000 000 Volts (20 MV) terminal
– H- stripped to proton: 40 MeV energy
– O- (Oxygen) stripped to O5+: 120 MeV energy
Charging pellets
Pelletron™
MAGNET TECHNOLOGY CENTRE
Tandem linear accelerator
The ESTU (Extended Stretched TransUranium) tandem accelerator at the A.W. Wright Nuclear
Structure Laboratory, Yale University
21 MV terminal
Intensities up to
20 microamps
30 meters long
SF6 gas insulation
(green house gas
problems)
MAGNET TECHNOLOGY CENTRE
Linear accelerator (LINAC)
From DC acceleration to AC / RF acceleration
Ion source
on
p+
Target on
ground
potential
DC
HV terminal
700 kV
600 kV
500 kV
400 kV
200 kV
100 kV
0 kV
AC
p+
Ion source on
ground
potential
300 kV
+/- 100 kV
+/- 50 kV
AC / RF
MHz … GHz
Target on
ground
potential
MAGNET TECHNOLOGY CENTRE
RF LINACs
© GSI
Why RF?
© CERN
– Electric fields:
DC: 1 MV/m
MHz: 10 MV/m
GHz: 100 MV/m
To reach
1 Gigavolt:
10 m GHz LINAC (1 km with DC)
1 Teravolt:
10 km GHz LINAC (1000 km with DC
impossible)
CLIC @ CERN (Design study for a 3 TeV e+e- Linear Collider, site length 48 km)
MAGNET TECHNOLOGY CENTRE
Circular accelerators
- Use the same RF structure and make the particles circulate many turns
inside the accelerator
Single pass
RF RF RF RF
PARAMETERS CHECK LIST
Beam energy
Velocity
Frequency
Magnetic field
RF
Large dipole
magnet is
needed for
bending
MAGNET TECHNOLOGY CENTRE
Cyclotron
Static magnetic field
Constant Radio Frequency
© Ernest Lawrence, 1929
University of California, Berkeley
MAGNET TECHNOLOGY CENTRE
Cyclotron - largest
TRIUMF, Canada's National
Laboratory for Particle and Nuclear
Physics
H- ions to up to energies of 520 MeV
Magnet diameter 18 m
Magnet weight 4000 tons
RF: 23 MHz, 94 kV
MAGNET TECHNOLOGY CENTRE
Cyclotron
Synchrotron
Lower cost per GeV
1 pulse / second
6
10 pulses / second
cc
A
(2)
ion
t
a
r
ele
(3) Extraction
(a lot of iron is saved)
(1) Injection
RF
Cyclotron
Const. Frequency
Const. Magnetic field
RF
Synchrotron
Frequency increases with E
–
If not ultrarelativistic
Magnetic field increases with E
MAGNET TECHNOLOGY CENTRE
Synchrotron
In picture: Brookhaven national laboratory / Alternating Gradient Synchrotron
(AGS) under construction (in 1957). Emax = 33 GeV
Many Nobel Prizes to accelerator physicists!
This machine only:
– Samuel C.C. Ting:
Discovery of the J/psi Particle
(1976)
– James W. Cronin and
Val L. Fitch:
CP Violation (1980)
– Leon Lederman,
Melvin Schwartz and
Jack Steinberger:
Discovery of the Muon-Neutrino
(1988)
© BNL
MAGNET TECHNOLOGY CENTRE
Synchrotron
Accelerator magnets
– Dipoles (for bending)
– Quadrupoles (for focusing)
– Sextupoles (for beam manipulation
and error correction)
– Octupoles (for beam manipulation
and error correction)
– Special fast pulsing magnets for
injection and extraction
Often the bending magnets are only
about 50% of the synchrotron length
MAGNET TECHNOLOGY CENTRE
Synchrotron collider
One beam pipe (CERN-LEP)
electron – positron
proton – antiproton
Two beam pipes (CERN-LHC)
electron - electron
proton – proton
or for example lead – lead
MAGNET TECHNOLOGY CENTRE
Superconducting components in
accelerators
Magnets, RF cavities, beam diagnostics & instrumentation
MAGNET TECHNOLOGY CENTRE
Superconducting cyclotron
Superconducting 250 MeV Cyclotron for
proton radiation therapy
Commercially available (ACCEL Instruments
GmbH)
Center 2.4 T
Conductor 4 T
D = 3.2 m
© Accel
© PSI
MAGNET TECHNOLOGY CENTRE
SC Radio Frequency cavities
A collection of SCRF cavities developed at Cornell University
with frequencies spanning 200 MHz to 3 GHz.
MAGNET TECHNOLOGY CENTRE
Development of SCRF cavities
MAGNET TECHNOLOGY CENTRE
Magnet systems of ion sources
Particle accelerator needs particles to accelerate
need of sophisticated ion sources
MAGNET TECHNOLOGY CENTRE
Atom to ion (ionization)
Neutral carbon atom
-
Charged carbon - ion
-
One electron is missing
Positive total charge
-
-
”Feels” electric and
magnetic fields
6+
-
Accelerators
-
-
-
MAGNET TECHNOLOGY CENTRE
Electron Cyclotron Resonance Ion Source (ECRIS)
Microwaves will heat
the gas to plasmastate, which is trapped
in a ”magnetic bottle”
Injection:
microwaves +
gas
Highly charged ions
are extracted via
high voltage
Strong magnetic field:
Solenoids (electric magnet)
Permanent magnet
multipole
MAGNET TECHNOLOGY CENTRE
ECR Ion Source: VENUS
SC hexapole inside SC solenoids
– Strong forces
– Gamma-radiation heat load to cryostat
© LBNL
© LBNL
© LBNL
MAGNET TECHNOLOGY CENTRE
CERN & LHC
Conseil Européen pour la Recherche Nucléaire
(European Council for Nuclear Research)
History
Today
Future (?)
MAGNET TECHNOLOGY CENTRE
CERN
Established on 29 September 1954
20 member states and 8 observers
Located close to Geneva on Swiss-France border
Its main function is to provide particle accelerators and
infrastructure for high-energy physics research
2600 full-time employees + some 8000 scientists and
engineers working in related projects
The World Wide Web began in CERN, in a project
initiated by Tim Berners-Lee and Robert Cailliau (1989)
MAGNET TECHNOLOGY CENTRE
CERN accelerator complex today
C ir
p+: 7 TeV
m
7k
2
nce
e
r
e
f
cu m
Pb54+: 575 TeV
450 GeV
50 MeV
1.4 GeV
28 GeV
MAGNET TECHNOLOGY CENTRE
CERN & LHC
MAGNET TECHNOLOGY CENTRE
LHC dipoles
© CERN
© CERN
© CERN
© CERN
MAGNET TECHNOLOGY CENTRE
Magnets systems of particle detectors
MAGNET TECHNOLOGY CENTRE
CERN - CMS Experiment
(Compact Muon Solenoid)
The silicon strip tracker of CMS
MAGNET TECHNOLOGY CENTRE
© CERN
MAGNET TECHNOLOGY CENTRE
CMS Magnet
MAGNET TECHNOLOGY CENTRE
MAGNET TECHNOLOGY CENTRE
CERN & LHC
A Toroidal LHC ApparatuS
ATLAS
Compact Muon
Solenoid
CMS
ATLAS Experiment
MAGNET TECHNOLOGY CENTRE
© CERN
• 25 MB / event
• 40 MHz
• 1 Petabyte/s
Triggering allows to
reduce the data
• 100 MB/s
1 PB / year
MAGNET TECHNOLOGY CENTRE
LHC is a big SMES(H)
One LHC dipole stores 7.8 MJ (0.12 H, 11.5 kA)
–
(weight 26 tonnes
equivalent KineticE
– There are 1232 dipoles
88 km/h)
10 GJ
+ ATLAS: 1.2 GJ
+ CMS: 2.7 GJ
+ Additional 400 smaller SC magnets
Also the beam stores a lot of energy!
– 2 x 362 MJ = 724 MJ (two beams)
– Beam dump needs to absorb 362 MJ of beam energy in the 90
μs circulation time, which equates to a power of 4 TW.
MAGNET TECHNOLOGY CENTRE
CERN ECR Ion Source
First experiments with proton – proton (collision energy = 14 TeV)
After: lead – lead (collision E = 1150 TeV)
– Produced Pb27+
Stripped to Pb54+
MAGNET TECHNOLOGY CENTRE
CERN – future (?)
Compact Linear Collider (CLIC) study
– Maximum achievable accelerating field (>150 MV/m) in order to lower the cost per GeV
– Needs a lot of
high power
RF system
development