energy flow studies

Energy Flow Studies

Steve Kuhlmann

Argonne National Laboratory

for Steve Magill, U.S. LC Calorimeter Group

Introduction/Outline

Detector is the “Small” Detector (Si-W EM Cal, 5 mm X 5mm, R=127 cm, 17%/E) (Fe-Scint HAD Cal, 1 cm X 1cm, R=144cm, 60%/E)

Software is JAS2 and GIZMO simulation

Conversion to Geant4 “soon”

Real Track Pattern Recognition Included

Will Discuss:

Brief Photon Review and Plans

Initial work on the Real Challenge: Neutrons/KLongs

Resolution components of Hadronic Z Decays at s = 91 GeV

Assuming Perfect Identification in this Detector Configuration

•Neutrons+KLong 2.9 GeV

•Photons 1.4 GeV

•Tracks 0.25 GeV

Put together in Tesla TDR in Energy Flow algorithm

Hadronic Z Decay

Simple 3 cut analysis

1. Reject EM Clusters if within Delta-R<0.03 from Track (0.2% loss of real photons)

2. Shower Max Energy > 30 MeV (MIP=8 MeV)

3. Reject EM Cluster if Delta-R< 0.1 AND E/P<0.1

Java code is available at:

www.hep.anl.gov/stk/lc/uta/

Will be put in CVS Server “soon”

http://www.hep.anl.gov/stk/lc/uta/

Hadronic Z Decays at s = 91 GeV

Total Hadron Level Photon Energy (GeV)

Tot

al P

hoto

n C

andi

date

Ene

rgy

Mean=0.25 GeV, Width=2.8 GeV, Perfect EFLOW Goal is 1.4 GeV.


Total Photon Energy - Total Monte Carlo Photons (GeV)

Energy Fragments from a Single 10 GeV -

Current Photon Work

1. Reject EM Clusters if within Delta-R<0.03 from Track (0.2% loss of real photons)

2. Shower Max Energy > 30 MeV (MIPS=8 MeV)

3. Reject EM Cluster if Delta-R< 0.1 AND E/P<0.1

Replace these two cuts with SLAC NNet-based ClusterID package.

(Worked on technical difficulties with Bower after UTA,

not solved)

Neutron/K0L Content of Hadronic Z Decays at s = 91 GeV

Neutron/K0L Energies in Hadronic Z Decays at s = 91 GeV

Neutrons/K0L, Mean E=4.4 GeV

Neutrons/K0L, Mean E=4.35

Study of >2 GeV Neutron/K0L overlapping >2 GeV Tracks

Study of >2 GeV Neutron/K0L overlapping >2 GeV Tracks

Angular Separation (radians) Angular Separation (radians)

Separation between Track and Closest N/K0L

Separation between N/K0L and Closest Track

Overflow bin

10% overlap within Sep<0.2




Overflow bin

Overlapping Showers from Other Tracks

41% overlap within Sep<0.2 72% overlap within Sep<0.4

Separation between random >2 GeV Track and Closest >2 GeV Track

Angular Separation (radians)16% overlap within Sep<0.1 59% overlap within Sep<0.3

Single 10 GeV Charged Pions: Basic Shower Widths

Angular Separation (radians)

Single 10 GeV Charged Pions: Means and Widths

Mean Width Width

All Hits 8.3 GeV 19% 60%/sqr(E)

Cone<0.4 8.1 GeV 21% 67%/sqr(E)

Cone<0.3 7.9 GeV 22% 68%/sqr(E)

Cone<0.2 7.5 GeV 22% 70%/sqr(E)

Cone<0.1 6.4 GeV 25% 80%/sqr(E)

Cone<0.075 5.8 GeV 28% 88%/sqr(E)

Single 10 GeV Charged Pions:

EM+HAD Energy (GeV) EM+HAD Energy (GeV)

All Hits Cone<0.2

These plots are with analog hadron cal, very similar with digital

Select Charged Pions isolated from other tracks in Z Decays, look

for Neutron Overlap

Cal Energy/Track P

No overlap from particle list

Overlapping Neutron/K0L

Two approaches being investigated:

1) Put calorimeter and track properties into neural

net.

List of calorimeter variables put into

ClusterID Net:

Tesla TDR approach

2) Careful removal of track depositions from Calorimeter. Used in

European package called “Snark”. Results similar to Tesla TDR, but larger

resolution tails.

Reminder, the Questions we eventually need to Answer

Detector Size and Hadron Calorimeter Resolution?

Digital or Analog Hadron Calorimeter?

Optimized segmentation for physics/costs?

Backup Slides

Question from Jeju and Calor2000: Will Hadronization or Jet Clustering Ruin Resolutions?

No, at least if backgrounds are small

Particle Energies in Hadronic Z Decays at s = 91 GeV

Charged, Mean E=2.85

Photons, Mean E=1.0

Neutrons/K0L, Mean E=4.35

Tracking cannot be assumed to be perfect, forward tracking and “curlers” are issues

Effect of ignoring charged particles below certain thresholds

Tesla TDR, is fine if achieved

Track Reconstruction Efficient Down to Pt=0.5 GeV in Barrel Region

Single 10 GeV -

Delta-R from EM Cluster to Track

EM

Clu

ster

Ene

rgy

(GeV

)

EM Clustering -- Cone 0.04

Reduce charged particle fragments with 3-layer shower max energy > 30 MeV

2 GeV Electron

2 GeV -

ddd

ddd

MeV

Also reduces neutron/K0L

clusters

Single 10 GeV -


EM

Clu

ster

Ene

rgy

(GeV

) Now With Shower Max Cut, will be improved with more detailed information on lateral/longitudinal profile

Effect of possible Photon threshold on Hadronic Z Decays at s = 91 GeV

Sum of all Hadron Level energy except photons < 0.2 GeV. Won’t apply such a cut (yet).

Photons are soft, Mean E=1.0


Simple photon finder: Remove EM Clusters within 0.03 of Track, unless track was MIP in all 30 layers. Then remove if within 0.01.


Probability of Overlapping Photon Close to a Track, 0.1% within DR<0.02, 3.3% within DR<0.1, 11% within DR<0.2

Determining Charged Particle Determining Charged Particle DepositionsDepositions

Energy deposited in last EM layer Energy deposited in last EM layer (within 0.6(within 0.600 of track) of track)

• Easy to recognize Easy to recognize MIPMIP

• Easy to determine Easy to determine 11stst layer of pion layer of pion showershower

Interactions

Single 2 GeV - Single 2 GeV Muon

Tail

OverflowsZeros

Determining Charged Particle Determining Charged Particle DepositionsDepositions

Single 2 GeV -

Energy weighted

Effect of Neutrinos in Hadronic Z Decays

One more cut motivated by Single 10 GeV -, now

either an Energy Ratio


EM

Clu

ster

Ene

rgy/

Tra

ck E

energy flow studies

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