1. Alushta 2014 Measurement of the electron beam transverse emittance at the JINR LHEP photoinjector test bench M. Nozdrin Conference-school of Young Scientists and Specialists of JINR Alushta’14 June, 02-08th 2014 Work is partially supported by the JINR youth grant № 14-103-02

2. M. Nozdrin. Measurement of the electron beam transverse emittance at JINR LHEP PTB2/13 Conference-school of Young Scientists and Specialists of JINR Alushta’14 June, 02-08th 2014 Introduction (photocathodes and photoinjectors) “Hollow” and “Transmissive” cathode conceptions Emittance and its calculation Diagnostic station Prospects Contents

3. M. Nozdrin. Measurement of the electron beam transverse emittance at JINR LHEP PTB3/13 Conference-school of Young Scientists and Specialists of JINR Alushta’14 June, 02-08th 2014 H. HertzA. StoletovA. Einstein Photoelectric effect

4. M. Nozdrin. Measurement of the electron beam transverse emittance at JINR LHEP PTB4/13 Conference-school of Young Scientists and Specialists of JINR Alushta’14 June, 02-08th 2014 Three-step photoemission model 1.Optical excitation of electrons from the valence band into higher empty states in the conduction band 2.Migration to the surface 3.Escape across the surface potential barrier into vacuum © R.A. Loch. Master thesis (2005)

5. M. Nozdrin. Measurement of the electron beam transverse emittance at JINR LHEP PTB5/13 Conference-school of Young Scientists and Specialists of JINR Alushta’14 June, 02-08th 2014 ParameterMetalsSemiconductors Quantum efficiencyLow (less than %)High (10% and more) Response timeLow (less than ps)High (up to ns) Required wavelengthUVVisible light, IR RobustnessHighLow LifetimeHigh (years)Low (months/days) PolarisationNoYes (NEA) Photocathode properties

6. M. Nozdrin. Measurement of the electron beam transverse emittance at JINR LHEP PTB6/13 Conference-school of Young Scientists and Specialists of JINR Alushta’14 June, 02-08th 2014 4-6 mm width washer with a cone (obliquity of 1:50) or cylinder aperture in the middle Such cathode geometry allows quantum efficiency rising due to surface photoelectric effect concerned to normal to material surface electric field multiplier Backside irradiation also simplifies laser beam targeting on emitting surface, accelerator equipment alignment and photocathode working surface laser cleaning “Hollow” and “Transmissive” cathode conceptions

7. M. Nozdrin. Measurement of the electron beam transverse emittance at JINR LHEP PTB7/13 Conference-school of Young Scientists and Specialists of JINR Alushta’14 June, 02-08th 2014 Photo-gun bench

8. M. Nozdrin. Measurement of the electron beam transverse emittance at JINR LHEP PTB8/13 Conference-school of Young Scientists and Specialists of JINR Alushta’14 June, 02-08th 2014 New bench

9. M. Nozdrin. Measurement of the electron beam transverse emittance at JINR LHEP PTB9/13 Conference-school of Young Scientists and Specialists of JINR Alushta’14 June, 02-08th 2014 Emittance © В.Н. Забаев. Применение ускорителей в науке и промышленности, 2008

10. M. Nozdrin. Measurement of the electron beam transverse emittance at JINR LHEP PTB10/13 Conference-school of Young Scientists and Specialists of JINR Alushta’14 June, 02-08th 2014 Pepper-pot technique Slit mask Pepper-pot mask © Min Zhang. Emittance Formula for Slits and Pepper-pot Measurement, 1996

11. M. Nozdrin. Measurement of the electron beam transverse emittance at JINR LHEP PTB11/13 Conference-school of Young Scientists and Specialists of JINR Alushta’14 June, 02-08th 2014 Diagnostic station Distance from mask to screen: [1] Min Zhang. Emittance Formula for Slits and Pepper-pot Measurement, 1996 Space between slits [1]

12. M. Nozdrin. Measurement of the electron beam transverse emittance at JINR LHEP PTB12/13 Conference-school of Young Scientists and Specialists of JINR Alushta’14 June, 02-08th 2014 Prospects Installation of the screen station instead of the fixed slit mask. Screen station will include the following equipment: Two slit masks with transversely-spaced slits (this will allow to measure emittance in both phase planes) Luminescent screen for beam divergence estimation and beam profile observation Probably, another mask pairs with different slit size or slit spacing

13. M. Nozdrin. Measurement of the electron beam transverse emittance at JINR LHEP PTB13/13 Conference-school of Young Scientists and Specialists of JINR Alushta’14 June, 02-08th 2014 Thank you for your attention!