J. Pozimski-FETS IC 10 May 2006 First experiences with the FETS pepperpot detector
J. Pozimski-FETS 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 !
J. Pozimski-FETS 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: nm
J. Pozimski-FETS IC 10 May 2006 Stopping power and range - basics Stopping Cross Section
J. Pozimski-FETS IC 10 May 2006 Stopping power and range of hydrogen in Phosphor SRIM (SRIM.ORG) simulation: Hydrogen in Scintillator material => Thickness and grain size
J. Pozimski-FETS 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
J. Pozimski-FETS IC 10 May 2006 Stopping power and range of hydrogen in Phosphor-LEBT
J. Pozimski-FETS IC 10 May 2006 Stopping power and range of hydrogen in Aluminium IAP -> thickness ~ 25nm ~1/3 range RAL -> thickness ~ 50nm ~1/7 range
J. Pozimski-FETS 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 ?
J. Pozimski-FETS 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.
J. Pozimski-FETS IC 10 May 2006 Comparison between the two experiments IAPRAL Beam diameter (mm)470 Beam current (mA) Beam energy (keV)635 Surface power flux (mW/mm 2 )32285 Surface current flux (mA/mm 2 ) Penetration depth (nm) max. Energy loss (keV/ m) 3575 max. power density (W/mm 3 ) av. power density (W/mm 3 )150480
J. Pozimski-FETS 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 ….. ?