1. Reminder of TPG background simulation Abingdon 30/10 -03 Rikard Sandström Geneva University

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 Setup 682 mm1682 mm z 10 MeV e -

3. Each 10 MeV e - gives 0.035 photons bremsstrahlung spectrum Most photons from entrance face Some photons from sides Initial values for photons from absorber

4. Most photons go through TPG volume end to end. Range of photons from absorber

5. Initial values for photo&Compton e -

6. These are just one time slot These are annoying: they go through the whole chamber Range of photo&Compton e -

7. Rescaling to the proposal … gives the following rates and numbers … proposal says 3 10 9 Hz of dark current 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 (not a problem) 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. In progress… Migrating code to G4MICE –Simulating muon tracks, in full experiment mode –Simulating background explicitly However, problems with inelastic meson events in G4MICE, and electrons are not correctly propagated at the present.