Status:1. Structured target resonance2. Magnetic suppression3. Low-Z LPM, Undulator-rad., Quantum
suppression
Plans:4. Heavy ion bremsstrahlung5. Positron production
STATUS
• 2x20 micron Au/Ta foils separated by 0 – 5000 microns (tolerance about 2 microns)
Signal ‘on top of’ about 2.0 (in these units) for separations in microns
2040120100
Structured target resonance
Measuring the formation length with a micrometer screw....
PreliminarySPS H4 exp., Sept. 2011
Structured target resonance
If the deflection angle over half a formation length
exceeds the ‘emission angle’
which happens for photons:
Suppression (crude model):
More elaborate theory needed...
Magnetic suppression
Magnetic suppression
•Material immaterial.•Higher fields move effect to higher photon energies.• Magnitude insensitive
•BUT: The effect will not be visible due to LPM suppression!
10% effect...
Magnetic suppression
•Material immaterial.•Higher fields move effect to higher photon energies.• Magnitude insensitive
NB!
300% effect!
Magnetic suppression
MCS
Field
The effect will not be visible due to LPM suppression!
Low-Z LPM• SLAC (1995) and CERN
(2001) indicate problems with low-Z targets.
• Test LPM theory in low-Z targets
• Analysis in progress (deconvolution of synchr. rad. poses problems)
from Electron/Positron Channeling in a Single CrystalA. Solov’yov, A. Korol, W. Greiner et al.
Initially tested (unsuccesfully) by NA63
Undulator radiation
Undulator radiationH. Backe, W. Lauth, A. Solov’yov, W. Greiner, U. Uggerhøj, J. Esberg, J.L. Hansen
Il Nuovo Cimento C, 34, 157-165, 2011Il Nuovo Cimento C, 34, 175-180, 2011
MAinz MIcrotron (MAMI)
0.01 0.1 1 10 1001E-3
0.01
0.1
10.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
0.0
0.2
0.4
0.6
0.8
1.0
I/Icl
0.001 0.01 0.1 1 10 100 1000 10000 1000000.001
0.01
0.1
1
10
Critical energy
Classical synchrotron radiation
Incident energy,Ee=10 GeV
Standard magnet, B = 1 T, 1m Si <110>max, Bequiv = 25.000 T, 0.1 mm
dN
/d
Photon energy [MeV]
Quantum Suppression
-4 -2 0 2 40.0
0.2
0.4
0.6
0.8
1.0
Qua
ntum
sup
pres
sion
of i
nten
sity
log10
(1/), log10
(C)
Synchrotron radiation Blankenbecler & Drell, eq. (7.5)
Classical: -> 0 => Cb -> infty
Quantum Suppression
Quantum Suppression
Analysis in progress• Factor 2 problem with normalization…
MonteCarlo
‘Fudge-factor’normalization
PLANS
Heavy ion bremsstrahlung33 TeV Pb82+ → Pb82+
γ = 170
Intact projectile
Scattering on a single rigid objectof charge Ze and mass M
Coherent scattering on Z quasi-free protons each of mass Mp
Incoherent scattering on individual quasi-free protons
Approx. binding energy per nucleon
Wavelength corresp. to nuclear size
Weizsäcker-Williams type calculation
BS never becomes the dominating mechanism in energy loss
Previous theories Now
Heavy ion bremsstrahlung
Heavy ion bremsstrahlung
Delta-electronsFinite nuclear size
…studies with aligned crystals – to be used for e.g. CLIC, LHeC previous studies with tungsten
High multiplicity and ’low’ energies (10 MeV e+)
Positron production
Positron productionMIMOSA detectors (M. Winter, Strasbourg)
• Vertex detectors for CLIC (?)
Positron production
Applications for funding – 100 kCHF – submitted
Funding expected by December 2011
11 MIMOSAs + DAQ delivered February 2012
Status:1. Structured target resonance2. Magnetic suppression3. Low-Z LPM, Undulator-rad., Quantum
suppression
Plans:4. Heavy ion bremsstrahlung5. Positron production