1. LEPTA: Low Energy Particle Toroidal Accumulator Presented by: Mkhatshwa S. L. Nkabi N. Loqo T. Mbebe N. Supervisor: A. Sidorin SA STUDENT PRACTICE 2010 DUBNA, RUSSIA 1

2. 2 cooling section positron trap septum kicker e-gun Helical quadrupole Ps detector 10E4 o-Ps per sec 22 Na 10E6 e+ per sec LEPTA FACILITY

3. 3 1. LEPTA facility е + sourceе + trapTransfer channelSeptum solenoids е - gun Collector Straight section Ps

4. 4 1. Particle dynamics in LEPTA 2. Electron cooling of positrons 3. Positronium generation in-flight 4. Experiments on Positronium physics 5. Feasibility studies of slow antihydrogen generation in-flight 6. Applied research (Positron Annihilation Spectroscopy) Main goals of the project

5. 5 Design parameters of the LEPTA Circumference, m 17.217.217.217.2 Positron energy, keV 10.0 Revolution time, ns 300 Longitudinal magnetic field, G 400 Average radius of the toroidal magnets, m 1.45 Helical quadrupole gradient, G/cm 10.0 Positron beam radius, cm 0.5 Number of positrons in the ring 1  10 8 Residual gas pressure, Тоrr  1  10  Positronium beam parameters Intensity, atom/s 1  10  Angular spread, mrad 1 Velocity spread 1  10  4 Beam diameter at the exit of the ring, cm 1.1

6. 6 4 5 4 7 12 9 9 10 3 8 11 6 1 - positron source 22 Na, 2 - radioactive protection shield, 3 - vacuum valve, 4 - vacuum chamber for pumping out and diagnostic tools, 5 -positron trap, 6 - vacuum isolator, 7 - positron vacuum channel, 8 - vacuum “shutter” (fast valve), 9 - ion pump, 10 - turbo pump, 11 - He vessel. Positron Injector

7. 7 The Cryogenic Source of Positrons

8. 8 Positron source

9. 9 Oscilloscope – measurement of cathode current (I) and voltage (V) Work on the Recuperator

10. Results 10 Graph of current against voltage

11. Work on the LEPTA Ring 11

12. 12 Application of voltage Electron gun Power Supply

13. Electron beam image (CCD Camera) 13

14. Electron beam image (illuminescent screen) 14

15. WORK TO BE DONE Measure: Shape of the beam Shape of the beam Charge in the accumulator Charge in the accumulator Lifetime of electron beam in the ring Lifetime of electron beam in the ring

16. Problems encountered No water No water No vacuum No vacuum Low emission Low emission Injector broke down Injector broke down

17. Conclusion We were able to measure the current of the electron beam against voltage. We were able to measure the current of the electron beam against voltage. Direct the electron beam, in the injector, from the gun to the collector (CCD camera). Direct the electron beam, in the injector, from the gun to the collector (CCD camera). Direct electron beam, in the ring, from the gun to the kicker (illuminescent screen). Direct electron beam, in the ring, from the gun to the kicker (illuminescent screen). Use vertical and horizontal correctional coils to direct the position of the beam. Use vertical and horizontal correctional coils to direct the position of the beam.

18. Acknowledgements NRF NRF Dr. Jacobs Dr. Jacobs Prof. Lekala Prof. Lekala JINR JINR A. Sidorin and his colleagues (LEPTA project) A. Sidorin and his colleagues (LEPTA project)

19. THE END THANK YOU THANK YOU ENKOSI ENKOSI SIYABONGA SIYABONGA