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