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Status:1. Structured target resonance2. Magnetic suppression3. Low-Z LPM, Undulator-rad., Quantum
suppression
Plans:4. Heavy ion bremsstrahlung5. Positron production
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STATUS
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• 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
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Measuring the formation length with a micrometer screw....
PreliminarySPS H4 exp., Sept. 2011
Structured target resonance
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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
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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...
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Magnetic suppression
•Material immaterial.•Higher fields move effect to higher photon energies.• Magnitude insensitive
NB!
300% effect!
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Magnetic suppression
MCS
Field
The effect will not be visible due to LPM suppression!
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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)
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from Electron/Positron Channeling in a Single CrystalA. Solov’yov, A. Korol, W. Greiner et al.
Initially tested (unsuccesfully) by NA63
Undulator radiation
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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)
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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
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-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
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Quantum Suppression
Analysis in progress• Factor 2 problem with normalization…
MonteCarlo
‘Fudge-factor’normalization
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PLANS
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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
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BS never becomes the dominating mechanism in energy loss
Previous theories Now
Heavy ion bremsstrahlung
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Heavy ion bremsstrahlung
Delta-electronsFinite nuclear size
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…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
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Positron productionMIMOSA detectors (M. Winter, Strasbourg)
• Vertex detectors for CLIC (?)
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Positron production
Applications for funding – 100 kCHF – submitted
Funding expected by December 2011
11 MIMOSAs + DAQ delivered February 2012
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Status:1. Structured target resonance2. Magnetic suppression3. Low-Z LPM, Undulator-rad., Quantum
suppression
Plans:4. Heavy ion bremsstrahlung5. Positron production