Simulation of RF background in MICE. Rikard Sandström University of Geneva NuFact’04 Osaka. Tracker. Introduction. Assumptions. Amount of background MICE proposal says 3 GHz (3 per ns) of RF induced electrons hit one of the outer absorbers. Good muon rate = 600 kHz (600 per ms)
Simulation of RF background in MICE
University of Geneva
z = -1849, -1379.72, -916.45, -394.76, 434.55, 900.8, 1367.3, 1833.55 [mm]
Trivial technical problem: the phase of the RF field in different cavities is hard to set correctly, so the electrons did not gain the maximum energy possible.
”Confined”: The particle was created inside the region of interest and was destroyed there as well.
”Immigrant”: The particle was created outside the region of interest and was destroyed inside the region.
”Emigrant”: The particle was created inside the region of interest and left the volume.
”Vagabond”: The particle was created outside the region of interest and left the volume.
Min E-loss for the 11.1 MeV peak
~ 8.7 MeV
200 000 e-(40 mu+)
e- from conversions
High energy electrons coming from RF
Some are later scattered back into the tracker again
102 kHz entered from target side
Photons entering with angle are mirrored against surrounding kapton
8.0 MHz go through all volume side to side
Dramatic change (again)!
RF Background & TPG
Typical event with background, TPG
Upstream, with BG
Downstream, without BG
RF Background & SciFi
The dominant source of background are electrons directly produced from the absorber (and windows)
E = ?
(x-axis not linear)
due to field