1 / 23

Round Beam Collisions at VEPP-2000

Round Beam Collisions at VEPP-2000. Dmitry Berkaev, Alexander Kirpotin, Ivan Koop, Alexander Lysenko, Igor Nesterenko, Alexey Otboyev, Evgeny Perevedentsev, Yuri Rogovsky, Alexander Romanov, Petr Shatunov, Yuri Shatunov , Dmitry Shwartz, Alexander Skrinsky, Ilya Zemlyansky. Novosibirsk

karina-baldwin
Download Presentation

Round Beam Collisions at VEPP-2000

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. Round Beam Collisions at VEPP-2000 Dmitry Berkaev, Alexander Kirpotin, Ivan Koop, Alexander Lysenko, Igor Nesterenko,Alexey Otboyev, Evgeny Perevedentsev, Yuri Rogovsky, Alexander Romanov,Petr Shatunov, Yuri Shatunov, Dmitry Shwartz, Alexander Skrinsky, Ilya Zemlyansky Novosibirsk 21.09.2011

  2. Layout of VEPP-2000 complex

  3. Collider overview L = 24.39 m facc= 172 MHz Vacc= 120 kV E=0.2 – 1 GeV Bbend = 2.4 T Bsol = 13 T β*=2 – 10 cm σs = 3 cm ε=1.4•10-7mrad νx,z= 2.1; 4.1 α= 0.036 ξ = 0.15 N± = 1011 L=1•1032cm-2s-1

  4. The Concept of Round Colliding Beams Small and equal β-functions at IP: Equal beam emittances: Equal betatron tunes: Angular momentum conservation z y x

  5. VEPP-2000 lattice

  6. Round beam options

  7. Positron beam lifetime(I+ = 20 mA)

  8. Machine tuning Closed orbit corrections Pick-ups Orbit Response Matrix to focusing offsets (4⊗32) SVD analysis steering coil corrections 2-3 iterations + minimizing of ƩIcor correctorssetting Δx; Δz ≃ ± 0.2 mm Lattice corrections BPMs ORM to steering coils modulations (20⊗36) SVD analysis focusing corrections (quads +solenoids) 3–4 iterations lattice setting β*;zero dispersion outside achromats; Coupling compensation 1.5 Tm field of CMD detector + solenoids compensating coils 3 families of skew quads ν1 – ν2 < 0.003

  9. Lattice corrections βx,βz(cm) βx,βz(cm) after 4 iterations Dx (cm) Dispersion βx,βz(cm) after 3 iterations

  10. Lattice and beam sizes (I± <1mA) 10

  11. ”Week-strong” beam-beam(“dynamic beta and emittance”) I+=3 mA; I-=48 mA 11

  12. “Strong-strong” beam-beam(“dynamic beta and emittance”) I+=61.8 mA; I-=53.2 mA

  13. Threshold current vs.tune(“week-strong”)

  14. Basic formulae of the luminosity: Beam profile measurements at 16 points ⇛ with dynamic β-functions and beam emittance, but under assumption: no other lattice distortions besides counter beam. Time of measurement ≃ 1 s at any energy. Luminosity measurements Bhabha scattering in the SND and СMD detectors Θscatt≥ 0.5 Main disadvantage⇛ low counting rate ≃ 10 Hz at L=1•1031 cm-2s-1

  15. Luminosity measurements (E = 837 MeV; Run 2011) L⁎10-30(cm-2s-1) t (sec)

  16. Luminosity at run 2011(CMD data) ramping ⇛ 16

  17. Luminosity vs.ξ

  18. Positron beam size vsξ

  19. Radiative polarization ζ ζ ζ 1.0 1.0 0.8 0.8 - + 0.6 0.6 0.4 0.4 - + 0.2 0.2 GeV GeV GeV 0 0 0.4 0.4 0.4 0.6 0.6 0.6 1.0 1.0 1.0 0.8 0.8 0.8 τp τp τp τp 104 104 102 102 1 1 + - sec sec 10-2 10-2 19

  20. Beam energy calibration E = 750.67 ± 0.03 MeV fd (kHz) 20

  21. 26.0 кГс 9,5 кА BEP upgrade (1GeV)

  22. Conclusion • Round beams give a serious luminosity enhancement. • The beam-beam parameter achieves a value ξ= 0.15 . • VEPP-2000 started up for data taking with 2 detectors. • Precise beam energy calibration is in progress. • To reach the target luminosity, more positrons are needed. • Booster BEP upgrade for beam transfer at 1GeV is being prepared.

  23. Thanks for your attention! Novosibirsk 21.09.2011

More Related