ILC Beam Dynamic. ILC= International Linear Collider. It is a project designed to smash together electrons and positrons at the center of mass energy of 0.5 TeV initially and 1 TeV later.
ILC= International Linear Collider
It is a project designed to smash together electrons and positrons at the center of mass energy of 0.5 TeV initially and 1 TeV later.
The ILC Global Design Effort team, established in 2005, has been making its accelerator design. Recently, it worked out the baseline configuration for the 30-km-long 500 GeV collider.
FLC / EUROTEV group
At high energy,
linear collider is
more cost effective
EnergyWhy a straight machine?
Bending a particle = loosing some energy
DE ~ (E4 /m4 R)
Exemple with e+/e- LEP experiment: Indirect determination of
the top quark mass.
Proves high energy reach
through virtual processes
ILC will provide a detailed map of new physics
cross sections few fb to few pb
e.g. O(10,000) HZ/yr
To achieve high luminosity small sizes at the interaction point have to be achieved
What is needed to reach high luminosity?
Before going to the world of beam dynamic, let’s have a look at the ILC
Long straight sections (e-/e+)
Upgraded energy (~1TeV)
To produce electrons, light from a titanium-sapphire laser hit a target and knock out electrons. The laser emits 2-ns "flashes," each creating billions of electrons. An electric field "sucks" each bunch of particles into a 250-meter-long linear accelerator that speeds up the particles to 5 GeV.
Damping Ring for electron beam
In the 6-kilometer-long damping ring, the electron bunches traverse a wiggler leading to a more uniform, compact spatial distribution of particles.
Each bunch spends roughly 0.2 sec in the ring, making about 10,000 turns before being kicked out. Exiting the damping ring, the bunches are about 6 mm long and thinner than a human hair.
2 main linear accelerators, one for electrons and one for positrons, accelerate bunches of particles up to 250 GeV with 8000 superconducting cavities nestled within cryomodules. The modules use liquid helium to cool the cavities to - 2°K. Two ~10-km-long tunnel segments, house the two accelerators. An adjacent tunnel provides space for support instrumentation, allowing for the maintenance of equipment while the accelerator is running.
5 nano m
Squeeze the beam as small as possible
for High luminosity
1 FODO cell
phase advance variation
Nominal focus. Quad. strength |k0|= 0.0524 m-2
Changed to |k1|= 0.0624 m-2
Phase advance (dependant on focusing strength)
Beta amplitude: b, periodic
(dependant on focusing strength)Motion
Where K(S) is the quadrupole strength and is periodic i.e. K(S)=K(S+2d)
One can get the solution in the form (Floquet’s theorem):
And get the differentiate along the beam axis:
Luminosity is then defined (gaussian beam) by:
Dispersion not included
Quality of the beam at IP and dependent of emittance prior to IP
Defined by focussing arrangement at IP
The challenge with the (normalised) emittance is that along a transport line it can only get worse.
When bunch is offset wrt cavity axis, transverse (dipole) wake is excited.
Multibunch emittance growth for cavities with 500mm RMS misalignment
The misalignements contribute largerly into the emittance growth along the linac.
RMS random misalignments to produce 5% vertical emittance growth
BPM offsets 11 mm
RF cavity offsets 300 mm
RF cavity tilts 240 mrad
Beam Based Alignment is crucial
KiBeam Based Alignment
Standard notation used: i.e. focusing for x, but defocusing of y
steererA BBA solution? 1-to-1 steering
simply apply one to one steering to orbit: i.e. at each BPM zeroing the orbit with a steerer such that the bunch centroid is in the central axis of the quad.
But BPM are offset wrt quad.
Dispersion are increased
(Particle with different energy will undergo a different angle in electromagnetic field)
DFS lower emittance growth
DFS along linac
With 2 beams
Normalized emittance (m.rad)
Good result for DFS technique.
- Benchmarking of the various DFS algorithm are being done
- Dynamic effect of ground motion not included
No position jitter
How to measure the emittance:
At Several (≥3) locations measure beam size emittance
It is foreseen to use laser-wires (finally focused laser) diagnotics system to perform emittance measurements.
Hor. beam size
Ver. beam size
4.5 to 12
3 to 20
1000 to 100
100 to 10Laser-Wire at PETRA
First vertical beam size measurements: 2003
2005: New vacuum chamber faster scan
A new high power laser is being installed at PETRA will be used in 2006
2nd vertical plane at IP is in place for horizontal measurements
2005 2006 2007 2008 2009 2010
Global Design Effort
ILC R&D Program
Expression of Interest to Host
Here was presented a snapshot of studies related to the ILC Beam Dynamic.
More is done at DESY on:
Damping Ring, Bunch Compressor, Failure mode, Vibrations,…
Check Beam Dynamic activities website at DESY.
Picked up of lot of the plots, drawings, … from:
Both frequency spectrum and spatial correlation important for LC performance
105 parameters: some from LHC, some from ILC
Extrapolation of SUSY parameters from weak to GUT scale (e.g. within mSUGRA)
Gauge couplings unify at high energies,
Gaugino masses unify at same scale
Precision provided by ILC for sleptons, charginos and neutralinos will allow to test if masses unify at same scale as forces
SUSY partners of electroweak bosons and Higgs
cross section for anomalous single photon production
Emission of gravitons
into extra dimensions
d = # of extra dimensions
e+e- -> gG
measurement of cross sections at different energies allows to determine number and scale of extra dimensions
(500 fb-1 at 500 GeV,
1000 fb-1 at 800 GeV)
ΔsinΘW = 0.000013
ΔMW = 7 MeV
ΔMtop = 100 MeV