ACD Backsplash test at CERN in 2002 Published in AstroParticle Physics, 2004 (Moiseev et al.)

9 8 D 7 6 5 4 3 2

E, GeV 10 20 50 100 200 250 D,cm Calorimeter Test Sim Sn, 7.9X0  30 45 Pb, 7.9X0 Pb, 17X0 Pb, 30X0 Fe, 7.9X0 60 80 Background

Backsplash spectrum in ACD Energy dependence of backsplash

Distance dependence Material dependence (same # of X0)

Backsplash prediction for LAT Works for LAT calorimeter (8-10 X0 of CsI)

This prototype was tested at SPS CERN in September 2004 Beam test at CERN This prototype was tested at SPS CERN in September 2004 We had to be here instead of there (Monblan) It was very challenging to build real instrument for ~ $60K (many thanks to Tom Johnson, Deneen Ferro, Dawn Blackburn, Bill Daniels, Nick Kwiatkowski, Tom Huber …) Finally, to our common surprise, we: got it assembled on a beam - happy! made it running -very happy!! obtained results which from the first glance did not contradict with common physics - no words!!! Data analysis is on a way

Start… maybe stop right now? Trimming lead plates – GOOD JOB, professors! First 2 of 20 panes made - look not so bad so far…

Built! What a monster! On a beam! See sparkling protons Results!

Good-bye! Why not to try that now?