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Scintillator ECAL12th / Jun 2009 Gakujutsu-sousei
K. Kotera, Shinshu-u for GLD calorimeter G
Requirements for ILD Electromagnetic calorimeter
• performance• from a standpoint of particle flow
algorithm for the jet energy resolution• energy resolution• granularity• linearity• uniformity
• Magnetic field tolerance• Robustness• Low cost
Strip scintillator/MPPC
Wave length shift fiber
Strip scintillator/MPPC
5x5~10x10 mm2
- JERtotal = 30% / √E - at √s = 91 GeV
Our challenge• plastic scintillator
10mm x 45 mm x 3mm
• 1600 pixel MPPC in 4mm x 3mm x 1.4 mm package
• 1mmΦ WLS fiber MPPC
WLS fiber
Kyungpook National University (Korea) 作
Extrude method→low cost, it can make hole for WLS fiber simultaneously
prototype test and bench test
Prototype of ScECAL
Holding 3.5 mm thick W as the absorber behind the strip scintillatorsFrom DESY BT and bench test, hermetic cover with reflector is mandatory
hole to inlet LED light for Gain monitoring
Alternately placed x and y layers interleaving 3.5 mm thick W absorbers
9 MPPCs on a flat cable
a Strip Scinti.WLS fiber
MPPC housing
x layery layer
30 layer
18x4 strips
Prototype of ScECAL
Holding 3.5 mm thick W as the absorber behind the strip scintillatorsFrom DESY BT and bench test, hermetic cover with reflector is mandatory
hole to inlet LED light for Gain monitoring
Alternately placed x and y layers interleaving 3.5 mm thick W absorbers
9 MPPCs on a flat cable
a Strip Scinti.WLS fiber
MPPC housing
x layery layer
30 layer
18x4 strips
LEDNotches
Prototype of ScECAL
Holding 3.5 mm thick W as the absorber behind the strip scintillatorsFrom DESY BT and bench test, hermetic cover with reflector is mandatory
hole to inlet LED light for Gain monitoring
Alternately placed x and y layers interleaving 3.5 mm thick W absorbers
9 MPPCs on a flat cable
a Strip Scinti.WLS fiber
MPPC housing
x layery layer
30 layer
18x4 strips
background in CALICE
we
2005 2006 2007 2008
AnalogueScHCal@CERNe± 6-45 GeVπ± 6-80 GeV15 of 38lay.
AnalogueScHCal@CERNe± 6-90 GeVπ± 6-180 GeV38 lay.
SiWECal@FNAL18 cm x 18 cm x 30 lay.
AnalogueScHCal@FNALe± 1-32 GeVπ± 3-32 GeV38 lay.
Digital HCal
combined combined
StripScECal@DESY9 cm x 9 cm x 26 layer
e+ 1-6 GeVTile ScECal etc..
StripScECal@FNAL18 cm x 18 cm x 30 lay.
e± 1-32 GeVπ± 3-32 GeV
SiWECal@CERN18 cm x 18 cm x 30 lay.
SiWECal@CERN18 cm x 12 cm x 30 lay.
2009
May
20
09
ver
sion
Sep 2008 versionKEK BT
R&D for MPPC
Extensive efforts so far• Study and development of MPPC performance.
• First beam test at DESY ( 2007 Mar. )
• 9x2 strips/layer x 26 layer.
• e+ 1 - 6 GeV → good linearity.
• Successful as a first test, learned a lot of things
• Comparing scintillator types→extruded scintillator.
• hermetic cover of each scint. to avoid opt.cross talk.
• non-uniformity problem ( one of reason of large constant term of resolution
• KEK BT (2007 Nov.) to establish extruded scintillator performance.
• Many bench tests with MPPC+scintillator done.
9 cm
9 cm
×20 cm
goal of Sep 2008 FNAL BT
• Establish comprehensive study of combined ScECAL and HCAL
• Electronics, Construction,
• First comprehensive study of performance of ScECAL
• Linearity of energy response for 1- 32 GeV,
• Energy resolution for 1 - 32 GeV,
• Effect of tilted incidence of particles,
• Position dependence of response.
• observation of π0 events - separation 2γ
• Establish LED calibration system.18 cm
18 cm
×25 X0
Energy scan Sep 2008 linearity
The fluctuation of the deviation from linear fitting is less than 5%, in 12 GeV or more, it is less than 2%.The values of lower beam momenta should be discussed.
1 3 6 12 16 25 32 GeV
Electron energy spectra
Energy scan Sep 2008 linearity
The fluctuation of the deviation from linear fitting is less than 5%, in 12 GeV or more, it is less than 2%.The values of lower beam momenta should be discussed.
1 3 6 12 16 25 32 GeV
Electron energy spectra
PMT response
MPPC saturation
MPPC resp.
Energy scan Sep 2008 linearity
The fluctuation of the deviation from linear fitting is less than 5%, in 12 GeV or more, it is less than 2%.The values of lower beam momenta should be discussed.
1 3 6 12 16 25 32 GeV
Electron energy spectra
one of target of May 2009
Energy scan Sep 2008;Resolution
the center-regionσstochastic=14.96±0.09%σconstant==2.12±0.09%
the uniform-regionσstochastic=14.63±0.09%σconstant==1.86±0.09%
the Totalσstochastic=15.47±0.03%σconstant==1.88±0.03%
The difference between the center-region and the uniform-region is not so big . To get better constant term, the improvements of MPPC dynamic-range and scintillator uniformity are necessary.
π0 RunSep 2008
π0 RunSep 2008
π0 RunSep 2008
data Mokka
Mπ0 128.9±0.8 134.9±0.6
σ Mπ0 14.4±1.0 14.6±0.8
Feed back from Sep 2008 results to May 2009
• More detail steps of energy scan especially to investigate strange behavior in low energy region.
• data taking for position dependence of electron events.
• More high energy pion.
• More steps of angles of tilted incident particles.
• More high energy π0 to test the ability of cluster separation.
• solving some problems
• Dead drift chamber, LED system, Temperature system.
Sep 2008 and May 2009Sep 2008 May 2009
Energy scanUniform:1,3,6,12,16,25,32 GeVCenter: 1,3,6,12,16,25,32 GeV 1,2,4,8,12,15,20,30,32 GeV
Position scanCenter: 3,6,12,16,25,32 GeV 2,4,12,15,20,32,60(+) GeV
e- 15 GeV Tilt angle scan
e- Center:e-
π-π- Center:
1,3,6,16,25,32 GeVe-π-3,6,16,25,32 GeV10°: 2,4,8,15,20,32 GeVe-
π- 8,15,32 GeV20°:
π0 run
MIP calibration 32GeVμπ- 16, 25, 32 GeV π+ 60 GeV
~ @ 20℃ Tilt angle 20° @ 20℃@ 20℃, 25℃,
e-π- mixed 32 GeV
Issues to solve found in Sep 2008
• One of four drift chamber was dead.
• LED calibration system
• worse separation of p.e. peaks
• double pedestal peak
• Temperature measurement system was not healthy ( sometimes no signal, sometimes large jitter)
Issues to solve found in Sep 2008
• One of four drift chamber was dead.
• LED calibration system
• worse separation of p.e. peaks
• double pedestal peak
• Temperature measurement system was not healthy ( sometimes no signal, sometimes large jitter)
• Came back
•Partially modified
•Partially modified
• Stand alone temperature measurement system
May 2009
Temp.dep. of response;mean of energy sum in MIP run
dA
AdT! 3.7(%/K)
~ 20% off
dA/(AdT) = 3.7%/K is consistent with HCAL’s one. This is too large to explain using temp. dependence of MPPC gain measured by bench test ( corresponding to half of this variation ).
Energy response for e- w/o, w/ temperature correction
Beam energy [Gev]
0 5 10 15 20 25 30 35
Nu
mb
er
of
mip
s
0
500
1000
1500
2000
2500
3000
3500
4000
4500
SceCal::Energy linearitySceCal::Energy linearity
Effect ofMPPC saturation
High temp.condi.Low temp.condi.
Using one MIP constants W/ temperature correction
- Saturation correction will be done
Energy resolution for e-
• need more blush up
• Hint of reason of large constant term was found out →Taka’s talk
Pi/mucontaminati
on?
Non-zero constantterm ? (2.3%)
stochastic constant2008 15.0 ± 0.1 2.1 ± 0.12009 13.7 2.3
a crunching result of May 2009
Summary for Experiment part
• We are developing the strip scintillator colorimeter for ILD.
• After four beam tests, we are gradually establishing strip scintillator calorimeter technology to correspond the ILD requirements.
• MPPC properties ( noise, saturation, bias voltage, temperature dependence, ... ), Scintillator ( extrude method), detector construction, ...
• Linearity ( correction for MPPC saturation ), Energy resolution, temperature dependence of response,
• Hint of reason of large constant term was found out →Taka’s talk
Strip clustering algorithm
Strip clustering algorithm
• First 2d clusters are reconstructed.
• Each triplet is reconstructed from three 2d clusters
• A 3d cluster is reconstructed with triplets
n+1 = y layer
n = x layer
n-1 = y layer
Gravitational center of Energy
Calculated hit position
yx
z
IP
2d cluster
:Triplets
JER; Cell area dependence
• √s = 200 GeV, 91 GeV, reconstructing total energy of two jet event
• PFA by PandoraPFA
• O.K. JER < 30% (91GeV) with < 1.0 mm
• There is no difference between 0.5 cm segment and 1.0 cm segment for 91 GeV, while small difference for 200 GeVCell size (cm)
0 5 10 15 20 25 30 35 40
rms9
0(to
tal)
/ sqr
E(to
tal)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
sqrt(s) = 200 GeV
sqrt(s) = 91 GeV
0.5 1.0 2.0 3.53.01.5 2.5 4.0
RMS9
0/ √
E(G
eV)
JER: function of length of square cell
JER; width/length dependence
JER: function of length of square cell
ECal aspect ratio 0 0.2 0.4 0.6 0.8 1 1.2
rms9
0(to
tal)
/ sqr
E(to
tal)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
9.0 cm^2 5.0 cm^2 2.5 cm^2 1.0 cm^2 0.25 cm^2
ECal aspect ratio 0 0.2 0.4 0.6 0.8 1 1.2
rms9
0(to
tal)
/ sqr
E(to
tal)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.79.0 cm^2 5.0 cm^2 2.5 cm^2 1.0 cm^2 0.25 cm^2
91 GeV 200 GeV
1 cm x 5 cm
0.5 cm x 5 cmRMS9
0/ √
E(G
eV)
RMS9
0/ √
E(G
eV)
Aspect ratio: width/length of scintillator strip
• The low of conservation of resolution ?? by an area
• Progress of strip scintillator does not work well so far
30
- 4 Track が作られる.- 荷電粒子の場合 Tracker とのマッチングした Momentum と Cal Energy に差ができ,それを埋め合わせる過程で Fake Cluster が融合される.
- 融合するCluster search 範囲をを最適化.
Two-fold ambiguity
Strip の利点を生かせきっていない理由
- 長辺方向の Clustering を取り入れる.
Fake Cluster
(予測)
Summary for strip clustering part
• We are developing the triplet clustering method.
• JER does not depend on the aspect ratio as long as we keep the area of scintillator, so far.
• Two-fold ambiguity?
• optimizing the aspect ratio and area depending on the scattering ratio of incident particles into the calorimeter.
Summary & Plans• 数年に渡る研究開発の結果、ScECALの実現可能性と性能評価は
ほぼ成功し、テストモジュールの製作とビームテストは今回で終了。
• データ解析はまだまだこれからだが、GEANT4との比較やフィードバック、strip clusteringを含めた多くの結果が期待される。
• 今後メインになるのは、ビームテストのデータ解析やstrip clustering等 ソフトウェア中心の活動と思われる。
特にstrip clusteringはその性能を示すことが緊急課題。
• 同時に、MPPCやextruded scintillator等の要素技術もまだ改善の努力を要す。
• publish!
backup
応答非一様性のもたらす影響
非一様領域
Extruded TiO2
高一様性Scinti.
一様領域
Energy 分解能
Sign
al (A
DC
cou
nts)
Distance from MPPC (mm)
Extruded TiO2
0 45
MPPC
: 非一様領域
: 一様領域
領域 定数項(%)
一様 2.35±0.12
非一様 7.26±0.05
1-6 GeV electron beam test at DESY (2007)
0 0.7 0.7
0.2
0.1
0 1/√E(GeV) 1/√E(GeV)
0.2
0.1
0σ/
E
MIP
なぜ Fiber 読み出しをしているのに不均一?WLS fiber Atten. length > 3.5 m
35
1mm x 1mm MPPC sens.area
Fiber
~25% of MPPC
1mm Φ
Beam position (mm)Sig
na
l (A
DC
co
un
ts) Kuraray Kuraray Extruded
direct photon (25%)
w/ fiber w/o fiber
長て方向の応答依存性は Scintillator の Attenuation length, 反射材の性能の影響を受けるべきではない
Fiberを介さぬ光子を遮断するカラー
Position dependence of p.e.
Distance from MPPC side (mm)
# of
p.e
.
MPPC
FNAL TB expに採用
反射材としての効果も
JER; 長辺依存性,幅を固定
36
2 cm x 4.5 cm
- 理想的には長辺を変えても JER が変わらないこと- 幅0.5 cm の Cell は 2.0 cm までのばしてもJER は変わらない(91GeV)- これら JER 変化は大きいのか?
Scintillator length (cm) 0 1 2 3 4 5 6 7 8 9 10
RM
S90
/ sq
rt{E(
GeV
)}
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7 1.0 cm Width 0.5 cm Width
Scintillator length (cm) 0 1 2 3 4 5 6 7 8 9 10
RM
S90
/ sq
rt{E(
GeV
)}0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
1.0 cm Width 0.5 cm Width
91 GeV 200 GeV
RMS9
0/ √
E(G
eV)
RMS9
0/ √
E(G
eV)
37
calorimeter layer
0 10 20
mean e
nerg
y / layer
[MIP
s]
0
20
406 GeV/c
5 GeV/c
4 GeV/c
3 GeV/c
2 GeV/c
1 GeV/c
CALICE preliminary
1st configuration, central region
background in CALICE
we
2005 2006 2007 2008
AnalogueScHCal@CERNe± 6-45 GeVπ± 6-80 GeV15 of 38lay.
AnalogueScHCal@CERNe± 6-90 GeVπ± 6-180 GeV38 lay.
SiWECal@FNAL18 cm x 18 cm x 30 lay.
AnalogueScHCal@FNALe± 1-32 GeVπ± 3-32 GeV38 lay.
Digital HCal
combined combined
StripScECal@DESY9 cm x 9 cm x 26 layer
e+ 1-6 GeVTile ScECal etc..
StripScECal@FNAL18 cm x 18 cm x 30 lay.
e± 1-32 GeVπ± 3-32 GeV
SiWECal@CERN18 cm x 18 cm x 30 lay.
SiWECal@CERN18 cm x 12 cm x 30 lay.
KEK BT
2009
May
20
09
ver
sion
Sep 2008 version