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Electron Veto Counter. Masashi Kaneta 2006/4/13 K0 meeting. The Main back ground: e + e - pair. e + e - :Photon conversion is the main background in the NKS2 experiment Trigger will be made by (IH_Hits 2 OH_Hits2) Those tracks will be on a plane - PowerPoint PPT Presentation
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Electron Veto Electron Veto CounterCounter
Masashi Kaneta2006/4/13
K0 meeting
The Main back ground: eThe Main back ground: e++ee-- pair pair
• e+e-:Photon conversion is the main background in the NKS2 experiment– Trigger will be made by (IH_Hits2 OH_Hits2)
• Those tracks will be on a plane– e+e- direction is almost same with photon– bended in a magnet field
• Need to remove them on a trigger level
Trajectory of eTrajectory of e++ee- -
• 0.0-1.2GeV/c of electron/positron– Bremsstrahlung photon energy is up to 1.2GeV– Energy sharing Ee/E is 0 to 1
• Hits on both IH and OH
Rev. M
od. Phys. 13 (1941) 240
Ee/E0.0
108 [eV]109 [eV]
107 [eV]
1.0 Trajectories of electronas a function of momentum(0.2–1.2 GeV/c with 0.2 GeV/c step)
Hit distributions at OH positionHit distributions at OH position
• Monte-Carlo studies are done by Kenta Futatsukawa
• Hits information from OHH and OHV– there is a overlap around 55 degree
e+e-
from K0S
from K0S
p from
from
z range[cm]
fraction ofe+e- [%]
|z|<0.5 22.0
|z|<1.0 41.4
|z|<1.5 54.1
|z|<2.0 61.8
|z|<2.5 67.7
|z|<3.0 73.4
|z|<3.5 76.9
|z|<4.0 79.7
z [c
m]
[degree]
DesignDesign
• 5 cm height– same with Previous experimet (NKS)
• Hybrid counters• Plastic Scintilator counter (1cm thickness)• Lucite Cherenkov counter (2cm thickness)
– will place on the same plane
• Separated as 4 counters– to avoid absorption of light in the counter– but can not have so many counters– PMT’s used in NKS will be recycled
DesignDesign