1. J. Pozimski-FETS Meeting @ IC 10 May 2006 First experiences with the FETS pepperpot detector

2. J. Pozimski-FETS Meeting @ IC 10 May 2006 Experience from IAP setup (C. Gabor) Proton current <70µA 6 keV beam energy => ~32 mW/mm 2 Main Parameters -> Phosphor material -> Grain size (and number of the layer) of the phosphor screen -> Thickness of the layer -> Coating (Al reflection layer) -> Mechanic stability (water glass) -> electric contact necassary ?  Simulations (with TRIM/ SRIM) are reasonable !

3. J. Pozimski-FETS Meeting @ IC 10 May 2006 Scintillator material – phosphor powder ~ Efficiency ~ Emission spectrum ~ Luminescense decay time -> Max. thickness d ~ 100µm -> Grain size > 1µm (2 µm ) -> 3-4 layer of phosphor grains QE > 70% of CCD: 500-750nm

4. J. Pozimski-FETS Meeting @ IC 10 May 2006 Stopping power and range - basics Stopping Cross Section

5. J. Pozimski-FETS Meeting @ IC 10 May 2006 Stopping power and range of hydrogen in Phosphor SRIM (SRIM.ORG) simulation: Hydrogen in Scintillator material => Thickness and grain size

6. J. Pozimski-FETS Meeting @ IC 10 May 2006 Stopping power and range of hydrogen in Aluminium Al can improove the photon luminosity by reflecting them into the CCD camera

7. J. Pozimski-FETS Meeting @ IC 10 May 2006 Stopping power and range of hydrogen in Phosphor-LEBT

8. J. Pozimski-FETS Meeting @ IC 10 May 2006 Stopping power and range of hydrogen in Aluminium IAP -> thickness ~ 25nm ~1/3 range RAL -> thickness ~ 50nm ~1/7 range

9. J. Pozimski-FETS Meeting @ IC 10 May 2006 Pepperpot head after the measurements Discolouring extends over whole plate onto the aluminium frame  beam lager than expected. No damage of plate and copper, slight colour patterns on copper => from aluminium ?

10. J. Pozimski-FETS Meeting @ IC 10 May 2006 Scintillator damage pattern Strong damage of scintillator surface in the interaction regions, but there was still a signal & pattern shows angular distribution. It seems that the damage is not a simple hole burnt into the surface.

11. J. Pozimski-FETS Meeting @ IC 10 May 2006 Comparison between the two experiments IAPRAL Beam diameter (mm)470 Beam current (mA)0.0710 Beam energy (keV)635 Surface power flux (mW/mm 2 )32285 Surface current flux (mA/mm 2 )5.58.2 Penetration depth (nm)200600 max. Energy loss (keV/  m) 3575 max. power density (W/mm 3 )200620 av. power density (W/mm 3 )150480

12. J. Pozimski-FETS Meeting @ IC 10 May 2006 Next steps : Try IAP scintillator -different Al thickness -different grain size -different production method Try different scintillator -Plastic scintillator (radiation hardness) -Solid crystals (ruby, YAG, - available sizes) Reduce beam energy -Deceleration ….. ?