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HES HKS meeting. 8 Oct 2010 T.Gogami. Contents. H 2 O Missing mass tracking code POSITRON simulation. Λ. Acc. background. Missing Mass (H 2 O) From Shichijo’s ppt. D ebug. H 2 O target. +1 - +. 52 Cr. CH 2. H 2 O. 48% up. 40 % up. 16 % up. H 2 O target missing mass. CUT. - PowerPoint PPT Presentation
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HES HKS meeting
8 Oct 2010T.Gogami
Contents
• H2O Missing mass– tracking code
• POSITRON simulation
Missing Mass (H2O)From Shichijo’s ppt
Λ
Acc. background
Debug
• +1• - +
48% up
52Cr CH2
16% up40% up
H2O target
H2O
CUTH2O target missing mass
OLD NEW
•Number of event •S/N
Tracking code Tracking codeΛ Λ
HES χ2 < 300HKS χ2 < 300
Ratio of number of Λ event
• HES χ2 < 50 (Fixed)• HKS χ2 < x
Much more event
Simulationfor positron at target
e- ( 2.344 [GeV] )
Target
Virtual detector(4cm×4cm )
Thickness 1 [μm]
0.5 [cm]
POSITRON• Number• Angular distribution• Energy distribution
20000 events
Angular distribution of e+
• event : e+ = 100k : 1
• 8 [μA] = 5×1013
• Rate of e+
= 5×108 [Hz]= 500 [MHz]
52Cr target
SIMULATION
Generated 100M eventsHKS detect θ > 1°e+ generated in target should not be accepted in HKS==>Background in HKS has other root
Summary and to do• Summary– Tracking code modification
• Lambda event up (H2O target)
– Simulation around target• positron angular distribution
– e+ generated in target should not be accepted in HKS
• to do– Tracking code
• background reject routine– POSITRON
• Around target – H20 target model
• Hall prove entrance• Real data
– ADC
100 M electron on target (52Cr)[rad]
•e+
•Momentum > 800 [MeV]
Angular distribution of e+
12C target
SIMULATION
Pb
e,e+ b.g. in HKSTOP view
Side view
X [cm]
X’ [r
ad]
5 × 5 [cm2]
HKS - DHKS - Q
B.G mix rate in HKS trigger
just after pattern recognition==>cut bad combination of space point (like TOF_pre)==>CPU power , analysis time
52Cr (77124)
12C (76077)
9Be (76607)10B (76184)7Li (76184) .
×1044
a
b
B.G. mix rate = a/(a+b)
Developing
Generated e+ in Simulation
pe+ : 1.2±0.5 [GeV/c]θ : 0.124±0.124 [rad]φ : 2.64159±0.5 [rad]target : 12C 100[mg/cm2]
HKS D magnetHKS D magnet
Splitter magnet
beam:spherical uniform generation
no collimatorEM flag on