csi calibration using pi0 's produced by neutron-nucleus interaction ( kek-ps e391a experiment...
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CsI calibration using pi0 's produced by neutron-nucleus interaction ( KEK-PS E391a experiment ). S. Y. Lee Pusan National University. E391a Collaboration. High Energy Accelerator Research Organization, KEK Faculty of Science and Engineering, Saga University - PowerPoint PPT PresentationTRANSCRIPT
CsI calibration using pi0 'sproduced by
neutron-nucleus interaction( KEK-PS E391a experiment )
S. Y. Lee Pusan National University
E391a Collaboration
High Energy Accelerator Research Organization, KEK
Faculty of Science and Engineering, Saga University
Department of Physics, Yamagata University
Department of Physics, Osaka University
Research Center for Nuclear Physics, Osaka University
National Defense Academy of Japan
Department of Physics, Ibaraki University
Joint Institute for Nuclear Research (Dubna) Russia
Department of Physics, University of Chicago
Fermi National Accelerator Laboratory
Department of Physics, Pusan National University
I. Motivation
KL Nothing
pure CsI calorimeter 4 veto
systemCALIBRATION to EM Calorimeter
II. Methodsinvariant mass of produced by neutron nucleus interaction at Al target
n
Pure CsI
Arrays
)cos(1EE2m 212
π 0
), (i 21(ADC)gE jji25j
1j
Iteration Process Do i=1, 576 for given CsI Module Reconstruct invariant mass from all 2 event ( , other)
Take mean from the invariant mass distribution
Make correction factor
ENDDO
Update gains by respectively
Iterate above process until to get correct invariant mass peak of 0
iCsI
im
)()(0
0 2
m
m
m
mc
ii
iCsI
ig ii cg
(continued)Data Sample
according to distance between Target and CsI calorimeter
3 m : ~ 1.5 M reconstructed events 7 m : ~ 1.5 M reconstructed events
III. Correction to Incident Position and Angle(by M.C.)
1. Position correction at normal incident
Before correctionBefore correction After correctionAfter correctionIncident position (cm)
Center of gravity(cm
)
Center of gravity
Incident position (cm)
2. Correction to position and angle
Before correctionBefore correction After correctionAfter correction
10
Incident position (cm)
Center of gravity (cm
)
0 1 2
3 4 5
6
X axis : incident position(cm)
Y axis : center of gravity(cm)
3. Results (position and angular correction)
Before correction After correction
0m = 5.4 MeV/c2 0m= 4.1 MeV/c2
MeV/c2MeV/c2
IV. Iteration
Before Iteration
MeV/c2MeV/c2
After Iteration
Results (Iteration)
Before Iteration
= 4.1 MeV/c2
RMS of Mass Peak of Each CsIs
= 1.05 MeV/c2
~ 480 MeV/C2
After Iteration
= 3.7 MeV/c2
RMS of Mass Peak of Each CsIs
= 0.05 MeV/C2
~ 540 MeV/C2
0m 0m
m m
Gain Change (preliminary)
Before (from muon) mean : 2.3 MeV/pC
After Iteration mean : 2.7 MeV/pC
MeV/pC MeV/pC
V. Summary We improve the precision of CsI Calibration
Position and Angular Corrections
More Correct position of Gamma
Better reconstructed pi0 mass peak( 25 % improvement of sigma )
Iteration Process Additional 10 % improvement
Update gain constant
Proper mass peak position of and
Differential Angular Correction
Incident position (cm)
cog(=
n) - co
g(=
n-1
)
)0()1( ff
)1()2( ff
Correction FactorFor given CsI module
If gain is fully calibrated,
Take the ratio
, Assume
We can get ,
iCsI
)()(0
0 2
m
m
m
mc
ii
)((ADC)g(ADC)g)(EEm ooiioii cos1cos122
)cos1cos1220 ((ADC)g(ADC)g)(EEm o
coi
ci
co
ciπ
))(()( 20
o
co
i
ci
i g
g
g
g
m
m
m
m
g
g
o
co 0
iici gcg
Basic Properties of Pure CsI
: 4.53 : 1.85 Moliere : 3.8 : 5.6 : 36.5 : 36f, 620s
: 305f, ~480s
: 1.80 light output(rel) : 0.10f, 0.20s (4k )f
)g/cm3(
(cm)X 0
)/(/ cmMeVdxdE
(cm)Ins)(
)(max nm
Dn
MeVphoton /
Mean value distribution( mass peaks of reconstructed pion mass distribution of
CsIs)
Before (from muon) RMS : 1.05 MeV/c2
After Iteration RMS : 0.5 MeV/c2
MeV/pCMeV/c2MeV/c2
3. Results-more
Before correction After correction
0m = 5.3 MeV/c2 0m= 4.1 MeV/c2
Gain Change (preliminary)