Gas Electron Multiplier A Gas Electron Multiplier F

Gas Electron Multiplier A Gas Electron Multiplier (F. Sauli, NIM A 386 531 1997) is made by 50 m thick kapton foil, copper clad on each side and perforated by an high surface-density of bi-conical channels; 70 µm 140 µm 50 µm 31 x 31 cm 2 F. Murtas LUMI GEM 1

Gas Electron Multiplier Filed lines By applying a potential difference between the two copper sides an electric field as high as 100 k. V/cm is produced in the holes acting as multiplication channels. Potential difference ranging between 400 - 500 V F. Murtas LUMI GEM conversion and drift amplification transfer 2

Triple GEM geometries Gain ~20 ~20 ~8000 F. Murtas LUMI GEM 3

A Triple GEM luminometer 10 cm 2. 4 cm 64 pads 10 cm A triple GEM 10 x 10 cm 2 has been built with a 64 pixel 3 x 3 mm 2 The read out has been realized using 8 chip ASDQ (8 channel each) Actually non more than 64 channel readout is possible; but we are working on implementation of a new chip IDEAS with 64 ch each F. Murtas LUMI GEM 4

Movie on chamber This movie has been realized during the readout debug. F. Murtas LUMI GEM 5

A Triple GEM luminometer The chamber has been placed on BTF for tests with electrons and photons The chamber is readout with a 64 ch scaler with a time gate of 200 ns F. Murtas LUMI GEM 6

Electron Beam 1 electron 1 2 electrons 3 Hit Multeplicity Raw Data !!! Beam Spot F. Murtas LUMI GEM 7

Analysis number of electrons tagging electron efficiency 80 % (due to leakage) spatial resolution sx=sy= 3. 3 mm including beam spread F. Murtas LUMI GEM 8

Efficiency with electron Measurements with an LHCb Chamber (same structure) at BTF on September working range F. Murtas LUMI GEM 9

Working in progress Next days measurements with BTF photons After that possible measurement on Dafne F. Murtas LUMI GEM 10

Thecnical slides F. Murtas LUMI GEM 11

30 -1 -2007 ore 9: 15 run 1048 “linea fotoni” run su elettroni F. Murtas LUMI GEM 12

30 -1 -2007 ore 9: 15 Pedestal run 1049 F. Murtas LUMI GEM 13

30 -1 -2007 ore 9: 25 run 1052 fascio 2 -3 elettroni F. Murtas LUMI GEM 14

2 run su elettroni 1058 e 1059 picco del pedestals F. Murtas LUMI GEM 15