1 / 23

LCWS06 Bangalore March 12th 2006

The E166 experiment Development of a polarized positron source for the ILC. Karim Laihem on behalf of the E-166 collaboration. LCWS06 Bangalore March 12th 2006. Outline. The goal of the E-166 experiment at SLAC The ATF Compton experiment at KEK Photon transmission polarimetry

desiree-bowers
Télécharger la présentation

LCWS06 Bangalore March 12th 2006

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The E166 experiment Development of a polarized positron source for the ILC. Karim Laihem on behalf of the E-166 collaboration LCWS06 Bangalore March 12th 2006 E166 collaboration

  2. Outline The goal of the E-166 experiment at SLAC The ATF Compton experiment at KEK Photon transmission polarimetry The helical undulator The E-166 setup Data taking First results on photon and positron asymmetries E166 collaboration

  3. Energy spectrum e- Dump e- Dump D2 D1 Gamma Diagnostic Positron Diagnostic D3 e+ e- γ The goal of the E-166 experiment at SLAC • Experimental Demonstrationfor polarized e+ production • Final focus test beam (FFTB) at SLAC with 46.6 GeV electrons • 1 m long helical undulator produces circular polarized photons • Undulator radiation 0-10 MeV (Balakin & Mikhailichenko 1979) • Conversion of photons to positrons in 0.2 X0 W-target • Measurement of polarization of photons and positrons by Photon transmission method Target 46.6 GeV Undulator 10 MeV 1 m e- E166 collaboration

  4. E= 36±8 MeV 104/bunch Compton based Pol. e+Generation Emax = 56MeV Pol. g-ray generation: M. Fukuda et al. PRL 91, 164801 (2003) E166 collaboration

  5. e+ polarization (e+ run) T. Omori et al., arXiv:hep-ex/0508026 Phys. Rev. Lett. accepted e+ beam spin e- spin in Iron A(R)= +0.60 ± 0.25% e+ beam spin e- spin in Iron A(L)= -1.18 ± 0.27% e+ beam spin non e- spin in Iron A(0)= -0.02 ± 0.25% E166 collaboration ATF-Compton

  6. Summary of e+ Run and e- Run T. Omori et al., arXiv:hep-ex/0508026 PRL accepted e- Run e+ Run abs. A= 0.90 ± 0.18% abs. A=0.89 ± 0.19% Pe+ = 73 ± 15(sta) ± 19(sys) Pe- = 72 ± 15(sta) ± 19(sys) E166 collaboration ATF-Compton

  7. SIDE VIEW ~30 m Undulator Gamma Table Positron Table E166 setup in the FFTB TOP VIEW e+ Analyzing magnet Gamma Analyzing magnet helical undulator collimators Gamma Table Positron Table photons diag Positrons diag photons collimation Polarized photons production Dump magnets e- beam E166 collaboration

  8. The helical undulator I2 Helical winding whereI1 and I2 are in opposite directions. I1 z I1 = -I2 Undulator photons I1 I2 x e- beam y • Helical winding: • z component of the induced magnetic field cancels • remaining magnetic field describes a helical profile E166 collaboration

  9. Undulator Photon energy spectrum Undulator Photon degree of polarization Undulator photon “Energy and Polarization” 2nd Harmonic 1st Harmonic 2nd Harmonic 1st Harmonic E166 collaboration

  10. e+ e- e+ e- 0.5 X0 W (Tungsten) -> E166 X0 W (Tungsten)= 3.5 mm e- Positron Polarization profile created by the undulator photons (creation point) e+ e+ Polarization transfer in e+ e- pair creation e- Polarized γ beam From the Helical Undulator e+ Energy distribution (in and out the 0.5 X0 W target) The Positron production target E166 collaboration

  11. E166 collaboration

  12. Positron and Gamma table at the FFTB (SLAC) E166 collaboration

  13. Photon transmission polarimetry Transmission E166 collaboration

  14. Positron Analyzing Power Expected asymmetries and analyzing power versus positron energy G3 simulation based on the experimental setup of the proposal V. Gharibyan Most challenging task for E166 was to measure asymmetries ≤1% in the CsI - Calorimeter E166 collaboration

  15. What we have achieved in E166 ? (e+ and photon asymmetry) Positron Asymmetry Photon Asymmetry R. Dollan, H. Kolanoski, T. Lohse, HU Berlin K. Laihem, S. Riemann, A. Schälicke, DESY, Zeuthen E-166 note, February 28, 2006 G. Alexander, E. Reinherz-Aronis, Tel Aviv Univ. E-166 note, Dec. 19,2005 and Feb. 19, 2006 Peter Schuler, Vahagn Gharibyan DESY William Bugg. University of Tennessee E166 collaboration

  16. What about the e+ degree of polarization? Transmission Okay!!!! The asymmetry Okay!!!! Magnetization of the The Iron core of the analyzing magnet We still need “Aγ“!!!! The analyzing power E166 collaboration

  17. Field map Measurement at SLAC. MERMAID field map calculation. Figure 5: By with respect X position and Z position. E166 spectrometer magnetic field study E166 collaboration

  18. E166_Geant4_Simulation Figure 1:Synoptic scheme of the E166 e+/e- transportation system.. The present study concerns the region between the target up to the Point A, B and C (entrance of the spectrometer, exit of the spectrometer and reconversion target respectively). E166 collaboration

  19. Point B Point A Reconversion target C E166_G4_SIM Spectrometer Current 180 A as an example E166 collaboration

  20. 74% 68% 61% 53% 44% EGS simulation John Sheppard Qualitative study Covered range. Summary table of the most relevant parameter for positrons at the reconversion target. E166 collaboration

  21. What is needed in Geant4 for polarized Positron/Electrons studies ? • TARGET • Gammas: • GammaConversion • ComptonScattering • PhotoElectricEffect • Electrons and Positrons: • MultipleScattering • Ionisation • Bremsstrahlung Diagnostics (Polarimetry) Cross sections polarization dependent • Compton Scattering • Bhabha Scattering • Moller Scattering • Positron annihilation in Flight • .......... Polarization transfer to e-/e+ e+ e- e+ e- e- e+ Polarization traking (depolarization effects ?) Polarized γ beam From the Helical Undulator MAGNETIC FIELD: 0.5 X0 W (Tungsten) -> E166 X0 W (Tungsten)= 3.5 mm E166 collaboration

  22. Summary and outlook • E-166 had two excellent runs (June / September 2005). • Asymmetries measured at 6 positron energies. • The helical undulator fulfilled its task. • The analysis asymmetries in the expected range • It still takes some time to come up with a number for the photon and positron polarization • More detailed Geant4 E-166 simulation work is in progress • The analysis is ongoing…. E166 collaboration

  23. Thank you…… E166 collaboration

More Related