Experiments on strong field QED in crystals (CERN NA63) J.U. Andersen, H. Knudsen, S.P. Møller, A.H. Sørensen, E. Uggerhøj, U.I. Uggerhøj Department of Physics and Astronomy, Aarhus University, Denmark P. Sona Dipartimento di Fisica, Universitá degli Studi di Firenze, Polo Scientifico, Sesto F.no, Italy S. Connell, S. Ballestrero Johannesburg University, Johannesburg, South Africa T. Ketel NIKHEF, Amsterdam, Holland S. Kartal, A. Dizdar Department of Physics, Istanbul University, Turkey A. Mangiarotti Laboratório de Instrumentação e F í sica Experimental de Part í culas, Coimbra, Portugal Status Report
Results, Oct run 1. Trident production in strong fields 2. Formation length effects
Trident production
Trident production: Background (no target) in nearly complete agreement with GEANT simulation (= no big surprises) Contributes about 20% Trident (Klein-like) Setup optimized for detection of 1-10 GeV pairs from 200 GeV electrons
Non-aligned crystal JETP Lett.88:80-84,2008 Small multi- hit capability Geometric acceptance
Spectrometer efficiency
Aligned case
Single target Shul’ga-Fomin: Reduced multiple scattering – no suppression from LPM effect JETP Lett. 63, 873 (1996) Bethe-Heitler LPM
Measurements
Results, Oct run 1. Restricted energy loss 2. Formation length effects
Ogle effect Coherence length: Range for tagged e- beam: gamma: [1 10 3 ;4 10 5 ] Alternative (Akhiezer, Shul’ga): Loss of density effect 1. 2.
Sandwich target 10 layers: Ta (10 microns) Air (100 microns) Resonances from formation length
Wednesday, SPS malfunction in B3 (ground error) 12 hrs. lost, max. energy 180 GeV Ilias Efthymiopoulos, Bruno Chauchaix back in business (thanks!) 6 days lost, 5 days left
Ogle effect – suppression unlikely real, loss of density effect possible
Sandwich ’resonances’ (?) ’onset’ for 120 GeV e -
Plans for week in June
intensity proportional to the logarithm of the thickness intensity linear with thickness 1 week in June
Plans for weeks in autumn
Spin-flip
’Polarization time’
Similar situations ILC / CLIC Bunch-size: 300 0.6 μm 3, 2·10 10 particles Density: Å -3, 0.6 Å -3 (at IP) Si crystal Density: 0.05 Å -3, of Z = 14 Blankenbecler, Drell (PRD 36, 277 (1987), Quantum treatment of beamstrahlung: ”Pulse transforms into a very long narrow ’string’ of N charges.”
Spin contr. to beamstrahlung Blankenbecler and Drell, ”Quantum treatment of beamstrahlung”, PRD 36, 277 (1987) Radiation from crystal C ≈ 1/ χ Spin-flip contribution:
Blankenbecler and Drell, ”Quantum treatment of beamstrahlung”, PRD 36, 277 (1987) Spin contr. to beamstrahlung
Contribution of spin to radiation emission in crystals 2 weeks in autumn Crystals Beamstrahlung Time required for setting up + calibration in autumn: 1 week Total: 1 week in spring, 3 weeks in autumn
Strong interest (CTF3, L. Rinolfi) in positron- production studies with aligned crystals – to be used for e.g. CLIC Simulations. NA63 can measure this – addendum in preparation
Publications and summary
Publications From ’preparatory phase’ of NA63: testrun in 2004 NA63: run in 2007 NA63: 2007, Subm. April ’09 NA63: 2008, Subm. May ’09
From the proposal of NA63 Done. Analysis in progr. First observ., systematical 2009 Alternative routes superior 2009