1. Ultrarelativistic particles in matter Ulrik I. Uggerhøj (representing the Aarhus group) Department of Physics and Astronomy, Aarhus University, Denmark

2. The experiment – CERN NA63 Ultrarelativistic particles passing amorphous targets

3. Field line picture of radiation Animation by Kristoffer K. Andersen

4. LPM effect Ir Cu When the formation length exceeds the multiple- scattering length: suppression arises below: Semi-infinite target...

5. Animation by Heine D. Thomsen TSF effect

6. Logarithmic t dependence ’Radiation per interaction as a function of number of scatterings’ Transition between Bethe-Heitler and LPM regimes:

7. KPC effect Burkhardt – white line Chudakov – Black line (with thickness unc. limits), Contours Mutual screening of charges in the pair => reduced dE/dx?

8. Formation length Separation of electron and photon by a (reduced) wavelength (or the pair by 2 Compton wavelengths):  e+ e- 1/  2 _

9. Structured targets Measuring the formation length with a micrometer screw....

10. The experiment – CERN NA63 Ultrarelativistic particles passing crystalline targets

11. Crystals

12. Extremely strong electric fields 10 10 -10 11 V/cm 50 V / 0.1 Å = 5·10 10 V/cm Relativistic invariant: =1.32·10 16 V/cm

13. Strong fields The critical field: Exists at the surface of some neutron stars (magnetars) Strong – compared to what?

14. Beamstrahlung heavy ions SLC: χ (or  )  10 -3 NLC: χ (or  )  1 Electric field from one bunch boosted by 2  2 as seen by the other Superstrong field, but of short duration E 1s / E 0 =  3 Z 3 Extended nucleus: Z  172 Strong lasers Laser wavelength (and  energy) limited by non-linear Compton scattering χ (or  )  1  -collision scheme (Telnov et al.)

15. Plasma wakefields Transverse focusing forces: Lead to values for realistic parameters:

16. Trident production JETP Lett.88:80-84,2008

17. Trident enhancement in strong field Theory

18. Radiation emission

19. Classical -> Quantum synchrotron

20. Blankenbecler and Drell, ”Quantum treatment of beamstrahlung”, PRD 36, 277 (1987) Spin contr. to beamstrahlung

21. Spin-flip ’Polarization time/length’

22. Pair production

23. Deflection/extraction of high energy protons and heavy ions through bent crystals This and similar mechanisms under study for extraction and/or collimation for protons and heavy ions at the CERN LHC

26. Thank you for your attention!