電子線を用いた中重ラムダハイパー核分光実験の為の

電子線を用いた中重ラムダハイパー核分光実験の為の
高多重度用飛跡再現コードの開発
Department of Science, Tohoku University
Toshiyuki Gogami ( 後神利志 )
JLab E05-115 collaboration, 2009, JLab Hall-C
全体・解析
18aSG-2
川間
JPS 2011 autumn meeting, T.Gogami
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Contents
1.
2.
3.
4.
Experimental Setup of JLab E05-115
Motivation of Tracking Code Development
New Tracking Code
Summary & outlook
JPS 2011 autumn meeting, T.Gogami
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Contents
1. Experimental Setup of JLab E05-115
JPS 2011 autumn meeting, T.Gogami
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Experimental setup of JLab E05-115
Data taking : Aug-Nov 2009
p(e,e’K+)Λ
HKS chamber wire configuration
Tracking
2×10-4
7 [msr]
3 – 12 [deg]
7Li
2×10-4
8.5 [msr]
2 – 12 [deg]
, 9Be , 10B , 12C , 52Cr
( 7ΛHe , 9ΛLi , 10ΛBe , 12ΛB , 52ΛV )
2 - 50 [μA]
10 - 300 [THz]
JPS 2011 autumn meeting, T.Gogami
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Contents
2. Motivation of Tracking Code Development
JPS 2011 autumn meeting, T.Gogami
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Background event of HKS
REAL DATA
x [cm]
y [cm]
9Be
SIMULATION
, 38.4 [μA]
KDC1
KDC2
KDC1
KDC2
z [cm]
e+ from
𝑥
pair creation ∝
𝑋0
~2.24
H2O
~4.94
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Discrepancy of Number of Λ
CH2 Target
The number of Λ
NΛ ≈ Nexpect
12C
quasi-free
H2O Target
Λ
The number of Λ
NΛ ≈ ¼ Nexpect
Λ
Σ0
Acc. b.g.
REAL DATA
Black : hit wires
Blue : selected wires
Red : track
Σ0
16O
quasi-free
Acc. b.g.
REAL DATA
Black : hit wires
Blue : selected wires
Red : track
Lost events that we are interested in in tracking procedure.
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Contents
3. New Tracking Code
JPS 2011 autumn meeting, T.Gogami
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Conventional JLab Hall-C
tracking procedure
Real data
52
CHCr2 target
Good TDC
High multiplicity
Pattern recognition
KDC1
Black : hit wires
Blue : selected wires
Red : track
Solve left right
Select good combination
Combination selection with TOF counters
Track fit
Reduce hit wire combinations
(h_tof_pre.f)
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New tracking scheme
Good TDC
High multiplicity
Point
Pattern recognition
• Hit wire selection with TOF
• 1X & 2X
• Grouping
• Pre-PID
• Cherenkov detectors
• 𝑑𝐸 𝑑𝑥
Reduce hit wires to analyze
Solve left right
Select good combination
Combination selection with TOF counters
Track fit
Reduce hit wire combinations
(h_tof_pre.f)
JPS 2011 autumn meeting, T.Gogami
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DC hit info. selection with TOF
Gravity
CUT
~17%
CUT
Particle direction
~8%
Maximum gradient
Minimum gradient
JPS 2011 autumn meeting, T.Gogami
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Check works of the code
Gravity
• GREEN region
Selective region
• RED markers
Selected hit wires
• BLACK markers
Rejected hit wires
Particle direction
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Results of
Introduction of new Tracking Code
Increased !
Increased !
• NΛ ≈ ¼ Nexpect
H2OT.Gogami
JPS 2011 autumn meeting,
 NΛ ≈ ½ Nexpect
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Contents
4. Summary & outlook
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Summary & outlook
• Summary
– JLab E05-115 ( 7ΛHe , 9ΛLi , 10ΛBe , 12ΛB , 52ΛV )
– Develop New Tracking code for high multiplicity data (H2O, 52Cr
target)
» NΛ ≈ ¼ Nexpect
 NΛ ≈ ½ Nexpect
• Outlook
– Tracking code
• Add y-position of TOF counters
• Add Cherenkov information
– Tracking efficiency
– Parameter Optimization
JPS 2011 autumn meeting, T.Gogami
全体・解析
18aSG-2
川間
15
END
Thank you for your attention
E05-115 experiment, JLab Hall-C, 2009
JPS 2011 autumn meeting, T.Gogami
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HKS detectors
June 2009 in JLab Hall-C
1 [m]
HKS trigger
•CP = 1X ×1Y × 2X
•K = WC × AC
 CP × K
−
~18 [kHz]
(8 [μA] on 52Cr)
p
K+
π+
K+
p, π+
Cherenkov detectors -AC,WC• Aerogel (n=1.05)
• Water (n=1.33)
TOF walls -2X,1Y,1X(Plastic scintillators)
TOF σ
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≈ 170 [ps]
Drift chambers
-KDC1,KDC2σ ≈ 200 [μm]
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HES Detectors
HES D magnet
Drift chambers
- EDC1 , EDC2 TOF walls - EH1 , EH2 (Plastic scintillators)
σ ~ 300 [ps]
Time Of Flight
HES trigger
EH1 × EH2
e
~2 [MHz]
(8 [μA] on 52Cr)
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Data Summary
JLab E05-115 (2009/June – 2009/Nov)
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Singles rate summary
HKS
Up to ~30 [MHz]
HKS trigger
~ 10[kHz]
HES
COIN ≤ 2.0 [kHz]
Up to ~15 [MHz]
HES trigger
~ a few[MHz]
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Hit wires event display (2)
v v’
u u’
v v’
u u’
particle
particle
x x’
x x’
• GREEN region
Selective region
• RED markers & lines Selected hit wires
• BLACK markers & lines Rejected hit wires
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KTOF multiplicity
~2.7
~1.8
~6.5
~3.8
Multiplicity
of KDC are not only high52Cr , 77124
CH2 , 76314
but also TOF counters are! (for heavy target )
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Background event from NMR port
9Be
KDC1
These particles
come from
NMR port
KDC2
KDC1
KDC2
9Be
, 38.4 [μA]
KDC1
x [cm]
KDC2
Overhead view
y [cm]
KDC1
KDC2
Side view
9Be
HKS dipole magnet
, 38.4 [μA]
z [cm]
, 38.4 [μA]
Background events
Β≈1
e- , e+
NMR port
Events on HKS optics
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B.G. mix rate (real data)
b
a
B.G mix rate =
* hks ntulpe
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𝑏
𝑎+𝑏
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e+ simulation
SIMULATION
• To see
1. Number of event
2. Angle & momentum
of e+ generated in target
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Target thickness dependence
(Simulation)
SIMULATION
52Cr
H2O
9Be
12C
CH2
10B
7Li
Consistent with B.G. mix rate !
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Angle and momentum distribution
of positrons
SIMULATION
Generate these
event in HKS GEANT
(Next page)
HKS cannot accept positrons directly !
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e , e+ background
in GEANT simulation
e+ generated in target make HKS dirty
Number of
e+
Correlation
(Simulation)
KDC1
B.G. mix rate (Real data)
KDC2
e- , e +
Vacuum chamber
(sus304)
NMR port
(sus304)
• Generated particle : e+
• Distribution : spherical uniform
• Momentum : 860 – 1000 [MeV/c]
• Angle : 0 – 2 [mrad]
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• 1000 events
Apply to u,v-layer
v v’-layer
Selective region determined by
1X and 2X
Convert
x x’-layer
Applied to uu’ and vv’ layers , too.
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Hit wires event display (2)
v v’
u u’
v v’
u u’
particle
particle
x x’
x x’
• GREEN region
Selective region
• RED markers & lines Selected hit wires
• BLACK markers & lines Rejected hit wires
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Spectroscopic experiment
by (e,e’K+) reaction
e
p
e’-Spectrometer
e-
e
u
u
d
pe’
e + p ➝ e’ + K+ + Λ
Feynman diagram
γ* u K+
–s
s
u Λ
d
γ*
p
n
Λ
target nucleus
1.
2.
3.
Missing Mass HHY
K+
K+-Spectrometer
pK+
Large Momentum transfer
• Λ can be bounded in deeper orbit
Λ’s spin at forward angle
• Spin flip ~ spin non-flip
Proton  Λ
• Absolute mass value calibration
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JLab E05-115 experimental setup
e + p → e’ + Λ + K+
2×10-4
7 [msr]
3 – 12 [deg]
7Li
2×10-4
8.5 [msr]
2 – 12 [deg]
, 9Be , 10B , 12C , 52Cr
• (e,e’K+) experiment
Primary beam
• High intensity
Thin target (~100 [mg/cm2])
• High quality
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1.
2.
3.
Coincidence experiment
(K+ and e-)
Small cross section
( ~100 [nb/sr] ) 1/1000
Energy resolution
32
Sub MeV (FWHM)
JLab CEBAF ( Continuance Electron
Beam Accelerator Facility )
• (e,e’K+) experiment
1.
2.
3.
Coincidence experiment
(K+ and e-)
Small cross section
( ~100 [nb/sr] ) 1/1000
Energy resolution
sub MeV (FWHM)
• Requirements for accelerator
1. High duty factor (~100%)
2. High intensity ( >a few 10 μA )
3. Small emittance ( ~2 [mm・μrad] )
Small ΔE/E ( <1×10-4 )
100 [m]
CEBAF was unique
facility
before MAMI updated
Experimental Hall
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Coincidence time vs. Mass square
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Cherenkov cut
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Cherenkov light
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HESの構成
ED1
Max. Field Gradient
7.8[T/m]
Max. Current
800[A]
Total magnet weight
2.8[ton]
EQ2
Max. Field Gradient
5.0[T/m]
Max. Current
800[A]
Total magnet weight
3.1[ton]
ED
Max. Field
1.65[T]
Max. Current
1065[A]
Total magnet weight
36.4[ton]

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