1. TPG background simulation Video conference 11/9 -03 Rikard Sandström Geneva University/CERN

2. Production cut at 1 keV Tracking cut at 20 eV 4T magnetic field No electric field Looking in Active Gas Volume for initial kinetic energy, initial position, range, range in z-coordinate. Active Gas Volume TPG Gas Volume Kapton field cage HV plane, kapton&Cu Separating plane, kapton LiqH absorber 35 cm 2 absorber windows, Al, yyy microns Setup 682 mm1682 mm z 10 MeV e-

3. Each 10 MeV e- gives 0.035 photon bremsstrahlung spectrum Most photons from entrance face Some photons from sides

4. Most photons go through TPG volume end to end.

5. e-from photo-electric and compton

6. These are just one time slot These are annoying: they go through the whole chamber

7. Rescaling to the proposal … gives the following rates and numbers … proposal says 3 10 9 Hz of dark curent electrons. Assuming they are all 10 MeV (which is pessimistic?) they would give in the open gate of the TPG (50 microseconds) 150 000 e- and this would give 1-2 additional hit per time slot (OKOK) 10-20 electrons going through the whole volume. (much more annoying!) HOWEVER: these vagabonds are related to the high energy tail of the spectrum…. They have energies of 1-5 MeV and could constitute a problem for the sci-fi as well. More investigations on those vagabonds is necessary.

8. Future plans Try different gas mixtures Look at different electron energies what is the real electron spectrum?