Analysis strategy of high multiplicity data

Analysis strategy of high multiplicity data

Toshiyuki Gogami24/Feb/2011

Contents

1. Introduction– Status of multiplicity and rate

2. Origin of multiplicity of HKS– Simple simulation

3. Tracking– Problems and strategy to improve– Development • DC hit wire selection with KTOF

4. Outlook & Summary

Introductions

Analysis process

trackingx , x’ , y , y’ at Reference plane

x’ , y’ , pat Target

Missing Mass


x’ , y’ , pat Target

p : Λ , Σ0 ,12ΛB

Angle : Sieve slit

F2T functionF2T function

particle ID(select K+)

HKSHES

tune tune

This talk

Multiplicity of typical layer of chamberHES HKS

~1.13

~1.28

~2.24

~4.94

Multiplicity is high for HKS

Hit wires in KDC1

Overhead viewKDC1

Black : hit wires Blue : selected wiresRed : track


CH2 52Cr

Misidentification chance in hit wires selection increase !

REAL DATA REAL DATA

low high low high

Overhead view

Singles rate summaryUp to ~30 [MHz]

Up to ~15 [MHz]HES

HKS

HKS trigger ~ 10[kHz]

HES trigger ~ a few[MHz]

COIN 2.0 [kHz]

Rate dependences

Quadratic dependence Linear dependence

• Why residuals get worse with rate (Multiplicity) ?– Hardware ?– Tracking is worse ?– Parameters ?

KTOF multiplicity ~2.7 ~1.8

~6.5 ~3.8

CH2 , 76314 52Cr , 77124Multiplicity of KDC are not only high but also TOF counters are! (for heavy target )

Origin of high multiplicity (rate) in HKS

Background event from NMR port

z [cm]

y [cm]

x [cm]

These particles come from NMR port

HKS dipole magnet

NMR port

KDC1

KDC2

KDC1

KDC2

KDC1

KDC2

KDC1

KDC2

Background events

9Be , 38.4 [μA]

9Be , 38.4 [μA] 9Be , 38.4 [μA]

Events on HKS optics

Overhead view

Side view

Β ≈ 1e- , e+

B.G. mix rate (real data)

ab

B.G mix rate =

* hks ntulpe

e+ simulation

SIMULATION

• To see 1. Number of event2. Angle & momentum

of e+ generated in target

Target thickness dependence(Simulation)

H2O52Cr9Be

12C CH2

10B

7Li

Consistent with B.G. mix rate !

SIMULATION

Angle and momentum distribution of positrons

HKS cannot accept positrons directly !

Generate these event in HKS GEANT(Next page)

SIMULATION

e , e+ background in GEANT simulation

Vacuum chamber(sus304)

NMR port(sus304)

KDC1 KDC2

e- , e+

• Generated particle : e+

• Distribution : spherical uniform• Momentum : 860 – 1000 [MeV/c]• Angle : 0 – 2 [mrad]• 1000 events

Number of e+ (Simulation) B.G. mix rate (Real data)Correlation

e+ generated in target make HKS dirty

Tracking

Basic tracking procedure

Good TDC

Pattern recognition

Track fit

Solve left right

Select good combination


CH2 target

KDC1

52Cr target

Combination selection with TOF counters

Reduce hit wire combinations (h_tof_pre.f)

High multiplicity

Real data

New tracking scheme

Good TDC

Pattern recognition

Track fit

Solve left right




High multiplicity

• Hit wire selection with TOF• 1X & 2X • Grouping

• Pre-PID• Cherenkov detectors

Reduce hit wires to analyze

DC hit info. selection with TOF (xx’)

Selective region Maximum gradient

Minimum gradient

Particle direction

Gravity

CUT~8%

~17%

Procedure in “h_dc_tofcut.f”1. Get KTOF1X & 2X hit counter information2. Make combination of 1X and 2X hit counter if those two are in

same group (grouping) 3. Determine cut conditions on KDC1 & KDC24. Select Hit wires in KDC and Reorder them

CUT

Just applied to xx’-layers for test

Check works of the code

• GREEN regionSelective region

• RED markersSelected hit wires

• BLACK markersRejected hit wires

Seems to work well

Particle direction

Gravity

Results of TOF cut with grouping

CH2 , 2.0 [μA] , 76315

Shift

Same

Residual

Multiplicity

CH2 , 2.0 [μA] , 76315

σ 150 [μm] σ 150 [μm]

~2.3

~1.2

before after

x x’ x x’

Result of TOF cut with groupingOriginal code

With “h_dc_tofcut.f”Pure Selective regionallowance

allowance

KDC

Too strict

select

Optimal allowance

Good tracks hid by background appear ! Number of K+ ~2[%] up

Apply to u,v-layer

Applied to uu’ and vv’ layers , too.

Selective region determined by 1X and 2X

Convert

v v’-layer

x x’-layer

Check works of the code

• GREEN region Selective region• RED markers & lines Selected hit wires• BLACK markers & lines Rejected hit wires

v v’ u u’

x x’

v v’ u u’

x x’

KDC1 KDC2particle particle

Results of TOF cut with grouping (all layers)

Residual

Multiplicity

CH2 , 2.0 [μA] , 76315

σ 150 [μm] σ 150 [μm]

Multiplicity of uu’vv’-layers• CH2

• ~20% reduction• 52Cr

• ~5-10% reduction

Same

before after

Results of TOF cut with grouping (all layers)

Faster !

Increase !TOF cut works well

52Cr

CH2

52CrFaster !

Increase !

Parameters ?

Outlook• Tracking– HKS

• Pre-PID before pattern recognition of KDC – Rough cut of π+ , p , e with Cherenkov

• Improvement of hit wire combination selection– Still we have β 1 background particles

• Optimize TDC and ADC cut– Reduce KTOF multiplicity DC hit wire selection with TOF

should be better.

– HES• Parameter check– Different parameters should be used for heavy

target

Summary• Status of Multiplicity and rate– Higher in HKS than HES– Strongly dependent on target in HKS

• Origin of high multiplicity and rate– Should be e- , e+

• Because of simulation results and its beta

• Development of Tracking for high multiplicity target– TOF cut with grouping works well

• Analysis time is faster by 10%.• Multiplicity is decreased by 5~50%.• Number of K+ is increased by 25% for 52Cr target.• Residual is still bad for 52Cr. Need to study

End

HKS detectors

Strangeness 2010 at KEK

K+

p, π+

Drift chambers-KDC1,KDC2-TOF walls -2X,1Y,1X-

(Plastic scintillators)

Cherenkov detectors -AC,WC-• Aerogel (n=1.05)• Water (n=1.33)

1 [m] June 2009 in JLab Hall-C

HKS trigger• CP = 1X ×1Y × 2X • K = WC × AC

CP × K

~18 [kHz](8 [μA] on 52Cr)

−π+

K+

p

σ ≈ 250 [μm]TOF σ ≈ 170 [ps]


HES DetectorsDrift chambers- EDC1 , EDC2 -

TOF walls - EH1 , EH2 - (Plastic scintillators)

HES D magnet

HES triggerEH1 × EH2

~2 [MHz](8 [μA] on 52Cr)e

Time Of Flight

σ ~ 300 [ps]

Target Hypernucleus Thickness[mg/cm2]

Beam Typical rateHES/HKS/COIN

[kHz]Current [μA] Total charge[C]

7Li 7He 184.0 32.0 4.84 2000 / 7 / 0.9

9Be 9Li 188.1 38.3 5.33 2400 / 9 / 1.6

10B 10Be 56.1 38.7 6.25 1300 / 1 / 0.1

12C 12B 112.5 26.8 5.90 1200 / 5 / 1.0

52Cr 52V 134.0154.0

7.6 0.835.53

2000 / 17 / 1.8

Data summary

22nd Indian-summer school (SNP2010)

Λ

Λ

Λ

Λ

Λ

E05-115 ( 2009 Aug – Nov )

Target Hypernucleus Thickness[mg/cm2]

Beam

Current[μA] Total charge[C]

CH2 Λ , Σ0 450.8 2.0 0.28

H2O Λ , Σ0 ~500.0 2.7 0.20

Physics Data

Calibration Data

(@36μA)

Analysis process


x’ , y’ , pat target

Missing Mass


x’ , y’ , pat target

p : Λ , Σ0 ,12ΛB

Angle : Sieve slit

F2T functionF2T function

particle ID(select K+)

HKSHES

tune tune

450.8 [mg/cm2]2.0 [μA]38 [hours]

σ = 2 [MeV/c2](NOT TUNED)

p(e,e’K+)Λ

p(e,e’K+)Σ0

Multiplicity and Tracking

• Tracking 1. Resolution2. Number of event

Multiplicityaffect


Tracking for high multiplicity

CH2 target

particleCH2 target

mean ~ 2 hit

52Cr target

mean ~ 6 hit

52Cr target

particle KDC1 trackingBlue : selected wiresBlack: hit wires

Multiplicity of typical layer

Multiplicity

Trac

king

eff.

52CrCH2

Developing new code

Traditional JLab Hall-C tracking code cannot handle with high multiplicity data.

Multiplicity of typical layer in chamber

CH2 target 52Cr target

mean ~ 6 hitmean ~ 2 hit

CH2 target 52Cr target

mean ~ 1 hitmean ~ 1 hit

106layer

6 layer6

HES

HKS Multiplicity is high in HKS

Multiplicity for each layerTarget Run Number Beam [μA] Multi

KDC1-x (@PR)

Multi KDC1-x(@N)Thickness [mg/cm2]

CH2 450.0 76314 2.0 2.92 2.72

H2O 500.0 75972 2.7 5.75 4.937Li 184.0 76220 32.0 4.26 3.85

9Be 188.1 76607 38.4 4.73 4.1610B 56.1 76184 42.4 2.52 2.4612C 112.5 76077 38.8 4.42 4.12

52Cr 154.0 77124 7.6 6.42 5.14

Angular and momentum distribution of e+

HKS should not accept e+ directory.

HKS detectors

HKS

D-m

agne

t

Multiplicity

Multiplicity is higher for heavy target

KDC wire configuration

K+

zy

x

uu’xx’

vv’ CH2 , 2.0 [μA]

52Cr , 7.6 [μA]

Multiplicity distributiony

x

Number of tracks

TOP view TOP view

KDC1



CH2 52Cr

Pattern recognition in KDC

KDC wire configuration

K+

zy

x

uu’xx’

vv’

y

x

x

1. Test point2. Space point

x

y

30°

90°

150°

Space point

NFOM (“h_dc_tofcut.f” for all layers)

Allowance applied to uuvv’ layers

New tracking scheme

Good TDC

Pattern recognition

Track fit

Solve left right




High multiplicity

• Hit wire selection with TOF• 1X & 2X • Grouping

• Pre-PID• Cherenkov detectors

Reduce hit wires to analyze

2nd loop

DC hit info. selection with TOF

HitSelective region Maximum gradient

Minimum gradient

Particle direction

Gravity

CUT~8%

~17%

CUT

HTRACKING / h_dc_tofcut.f

Procedure in “h_dc_tofcut.f”1. Get KTOF1X & 2X hit counter information2. Make combination of 1X and 2X hit counter if those two are in

same group (grouping) 3. Determine cut conditions on KDC1 & KDC24. Select Hit wires in KDC and Reorder them

Just applied to x,x’-layers for test

Particle direction

Gravity

Documents

Analysis strategy of high multiplicity data