1. Status:
Structured target resonance
Magnetic suppression
Low-Z LPM, Undulator-rad., Quantum suppression
Plans:
Heavy ion bremsstrahlung
Positron production

2. STATUS

3. Structured target resonance
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
120 20 40
100

4. Measuring the formation length with a micrometer screw....
Structured target resonance
Measuring the formation length with a micrometer screw....
Preliminary
SPS H4 exp., Sept. 2011

5. Magnetic suppression
If the deflection angle over half a formation length
exceeds the ‘emission angle’
which happens for photons:
Suppression (crude model):
More elaborate theory needed...

6. Magnetic suppression 10% effect... 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...

7. Magnetic suppression 300% effect! NB! Material immaterial.
Higher fields move effect to higher photon energies.
Magnitude insensitive
300% effect!

8. Magnetic suppression MCS Field
The effect will not be visible due to LPM suppression!

9. 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)

10. from Electron/Positron Channeling in a Single Crystal
Undulator radiation
from Electron/Positron Channeling in a Single Crystal
A. Solov’yov, A. Korol, W. Greiner et al.
Initially tested (unsuccesfully) by NA63

11. Undulator radiation MAinz MIcrotron (MAMI)
H. Backe, W. Lauth, A. Solov’yov, W. Greiner, U. Uggerhøj, J. Esberg, J.L. Hansen
MAinz MIcrotron (MAMI)
Il Nuovo Cimento C, 34, , 2011
Il Nuovo Cimento C, 34, , 2011

12. Quantum Suppression

13. Quantum Suppression
Classical: -> => Cb -> infty

14. Quantum Suppression Analysis in progress
‘Fudge-factor’
normalization
MonteCarlo
Analysis in progress
Factor 2 problem with normalization…

15. PLANS

16. Heavy ion bremsstrahlung
33 TeV Pb82+ → Pb82+
γ = 170
Intact projectile
Weizsäcker-Williams type calculation
Scattering on a single rigid object
of charge Ze and mass M
Approx. binding energy per nucleon
Coherent scattering on Z quasi-free protons each of mass Mp
Wavelength corresp. to nuclear size
Incoherent scattering on individual quasi-free protons

17. Heavy ion bremsstrahlung
Previous theories
Now
BS never becomes the dominating mechanism in energy loss

18. Heavy ion bremsstrahlung
Delta-electrons
Finite nuclear size

19. Positron production
…studies with aligned crystals – to be used for e.g. CLIC, LHeC previous studies with tungsten
High multiplicity and ’low’ energies (10 MeV e+)

20. Positron production MIMOSA detectors (M. Winter, Strasbourg)
Vertex detectors for CLIC (?)

21. Positron production Applications for funding – 100 kCHF – submitted
Funding expected by December 2011
11 MIMOSAs + DAQ delivered February 2012

22. Status:
Structured target resonance
Magnetic suppression
Low-Z LPM, Undulator-rad., Quantum suppression
Plans:
Heavy ion bremsstrahlung
Positron production