1. Current Status of Pepperpot Emittance Measurement System Simon Jolly Imperial College FETS Meeting, 22/02/06

2. 22/02/06Simon Jolly, Imperial College 2 Purpose of Pepperpot Current measurements only give x-x’ and y-y’ emittance measurements, with no x-y correlation. Pepperpot system reduces granularity of emittance measurement to expand no. of measurements:  x-x’ and y-y’ emittance (from displacement/expansion of spots).  x-y profile (from arrangement of spots).  Space charge estimate (from longitudinal position of complete setup).

3. 22/02/06Simon Jolly, Imperial College 3 Pepperpot Principle Beam segmented by front plate with 25 x 25 grid of holes. Beam drifts ~10mm before interacting with phosphor and producing array of spots to be imaged by a CCD camera. Change in position of spots from expected gives emittance.

4. 22/02/06Simon Jolly, Imperial College 4 Pepperpot Components Tungsten grid (25 x 25 holes, 50  m diam, 3mm spacing). Copper block allows beamlets to expand. Phosphor screen images beamlets. Light from phosphor recorded by fast CCD camera (500ns shutter). Lens system mounted on camera improves resolution. Light path enclosed in light tight bellows. Whole system mounted on moving stage to allow longitudinal beam sampling (but camera- to-phosphor distance fixed).

5. 22/02/06Simon Jolly, Imperial College 5 FETS Pepperpot System (PJS) Complete Pepperpot assembly: Screen assembly produces beamlets and image on phosphor. Camera (+ lens) records phosphor image. Support structure “stolen” from previous system at RAL. Longitudinal motion from screw thread.

6. 22/02/06Simon Jolly, Imperial College 6 FETS Pepperpot System (2) Pepperpot screen assembly: Tungsten screen (50  m holes with 3mm spacing). 10mm thick copper block. Phosphor screen (P46 or P47 phosphor on glass substrate). Aluminium mounting block.

7. 22/02/06Simon Jolly, Imperial College 7 FETS Pepperpot System (3) Pepperpot camera assembly: PCO 2000 camera with 2048 x 2048 pixel, 15.3 x 15.6 mm CCD. Firewire connection to PC. 105 mm Micro-Nikkor macro lens (not shown). Whole structure mounted on moving stage: 3-arm spider improves sability.

8. 22/02/06Simon Jolly, Imperial College 8 Current status Camera ordered (arrived?) from Photon Lines with Nikon F-mount lens adapter and 500ns option. Software installed on PC at IC - tie in with Matlab. Nikon lens already purchased. Camera bellows ordered. Phosphor screens ordered (2xP46, 2xP47). Most mechanical components already made - just back plate left (problems with IC CNC machine). Problems with manufacture of tungsten grid: start with 100  m holes. Components for test assembly should be available at IC…

9. 22/02/06Simon Jolly, Imperial College 9 Next steps Manufacture back plate and find company to produce 50  m holes. Assemble and test complete setup at IC. Test/Calibration setup - parallel laser beam in place of ion beam/phosphor:  Beam expander and laser.  Optical bench and mount for back plate. Run software test and check “integration” with Matlab. Assemble system at RAL: aim was for 1st week of March; not that far off…