Working group on photon vetoes Meeting on June 7 th : 1.Status of Geant4 simulations 2.Discussion on LAV structure 3.Discussion on readout 4.News on Spaghetti (KLOE prototype) 5.Report on Tagged Photon beam Presented by P.Valente

Conclusions from last report

1. Status of G4 simulations Concentrating on creating a full LAV structure for the TileCal solution… …since SpaCal simulation is CPU demanding and still has some problem (thousands of fibers inside!)

1. Status of G4 simulations X 0  Full LAV layout, but 42.5 cm depth  No projectivity (straight bottom surface)

1. Status of G4 simulations X 0  Realistic materials, including:  Aluminum enclosure  Paper wrapping for tiles

1. Status of G4 simulations

 Realistic light yield, 25 p.e./MeV  No threshold applied  Look at 3 inefficiencies:  not seen, not interacting  seen by nearest ring  seen by any of the rings

1. Status of G4 simulations

 Inefficiency = 6×10 -4  Essentially punch- through, apart from border effects  X 0 are not enough!

2. Discussion on LAV structure  15 X 0 are not enough!

2. Discussion on LAV structure

1. Status of G4 simulations

Solve SpaCal problems…

Add to To-Do List

One more point to To-Do list: check effect of projective shape (Niels) 50 mrad

3. Discussion on readout  FADC vs. TDC/ADC drives a number of choices for the readout implementation

Yet another To-do for simulators… 1.Persistency at the hit level 2.Second step for digitization, signal shaping, etc. Optimize CPU Easy to change readout/shaping configuration

3. Discussion on readout Discussion has just started… Some of the questions on the table:

3. Discussion on readout

 Electronics on-detector  Virtual technical gallery

3. Discussion on readout  Crucial, in order not to spoil the inefficiency!  Paper reference histograms will not be adequate…

4. News on Spaghetti Lead Scintillating fiber Winston concentrator light guide …a reminder

4. News on Spaghetti How to make spaghetti? Go to Frascati… 1. Machine for making grooves in lead foils 2. Working prototype Black box: Light guides+PMT’s

4. News on Spaghetti Total energy distribution for 0,1,2,3… electrons Electrons energy = 500 MeV Prototype readout

 General description in the proposal as a backup solution  Still a lot of details missing, so…  …work on SpaCal simulation! Establish performance Compare with TileCal Refine design Compare realistic costs with TileCal  In the famous To-Do list of simulation activities…

5. Report on photon beam …where it will be

5. Report on photon beam Electron beam parameters

5. Report on photon beam Electron facility working efficiently since almost 3 years Good performance, good beam diagnostics Project of tagged photon beam in advanced status

5. Report on photon beam Active target inserted in the e- beam (Si microstrip, two x-y planes) Electrons from time to time irradiate Bremsstrahlung photons (thickness=0.02 X 0 ) Si microstrip tagging detectors inside the magnet measure the deflection of emitting electrons Impact point correlated with  E i.e. with E 

5. Report on photon beam

Signal pulse height vs. number of incoming electrons Beam spot on tagging target 3 mrad 13 mrad

5. Report on photon beam All photons Tagged photons: Only 2/7 tagger modules No analysis on energy resolution Poor statistics: all 384 strips together

5. Report on photon beam Si tracker 241 MeV tagged  converting in the Si tracker

5. Report on photon beam Geant 3 simulation…

5. Report on photon beam

Conclusions A long To-Do list for simulation activities…  a more and more detailed simulation of the LAV At the same time, start thinking at other important issues:  Readout  Signal shaping  Trigger  Monitoring Project for tagged photon beam at BTF (LNF) is advanced  Final installation in July, first runs in August  Tagging efficiency has to be carefully studied  Could be very useful even if could not be reached “Geant” simulation of logo…