Straw tube detector performance for the PANDA and COSY-TOF - - PowerPoint PPT Presentation

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Straw tube detector performance for the PANDA and COSY-TOF - - PowerPoint PPT Presentation

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I NTERNATI ONAL PHD PROJECTS I N APPLI ED NUCLEAR PHYSI CS AND I NNOVATI VE TECHNOLOGI ES This project is supported by the Foundation for Polish Science M PD program, co-financed by the European Union within the European Regional Development

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SLIDE 1

Straw tube detector performance for the PANDA and COSY-TOF experiments

Sedigheh Jowzaee

November 25, 2014 Jagiellonian University, Krakow, Poland

I NTERNATI ONAL PHD PROJECTS I N APPLI ED NUCLEAR PHYSI CS AND I NNOVATI VE TECHNOLOGI ES

This project is supported by the Foundation for Polish Science – M PD program, co-financed by the European Union within the European Regional Development Fund

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SLIDE 2

Outline

November 25, 2014 2 Sedigheh Jowzaee

  • PANDA experiment
  • Straw tube tracker
  • Simulation of straw tube performance
  • PID with straw tube
  • COSY-TOF experiment
  • Analysis of pp→pK+Λ reaction with STT data
  • Summary
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SLIDE 3
  • 1. PANDA Experiment

November 25, 2014 3 Sedigheh Jowzaee

  • PANDA is an experiment in the FAIR facility at Darmstadt ,Germany
  • Interaction of antiproton with momentum range (1.5-15 GeV/c)
  • Hydrogen Target (Charmonium spectroscopy, Exotic hadrons , …)
  • Nuclear Target (Hadron properties in the nuclear medium, spectroscopy of hypernuclei)

PANDA (antiProton Annihilation at Darmstdat) Program

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SLIDE 4

Target spectrometer Forward spectrometer

  • 1. PANDA Experiment

PANDA Detector

  • Full angular acceptance
  • Particle identification (p, π, K, e, µ) in the range up to ~ 8 GeV/c

November 25, 2014 4 Sedigheh Jowzaee

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SLIDE 5
  • 2. Straw Tube Tracker

November 25, 2014 5 Sedigheh Jowzaee

measure: tDrift  x

reconstruction

  • f particle

trajectory

  • The straw tube is a proportional counter, gas-filled cylindrical tube as a

cathode and a thin wire stretched along the tube axis as an anode

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SLIDE 6
  • 2. Straw Tube Tracker

November 25, 2014 6 Sedigheh Jowzaee

  • Straw tube structure
  • Al-mylar tube, Ø=10 mm
  • Gold-plated anode, Ø=20 µm
  • End plug, crimp pin and spring
  • Gas pipe (PVC med)
  • 2.5 g weight per tube
  • Advantages of straws
  • Modules (easy to exchange, high flexibility)
  • Low mass (self supporting by gas
  • verpressure )
  • High rates (1 MHz/wire)
  • Low aging
  • Fast readout (pulse shaping and

digitization)

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SLIDE 7
  • 3. Simulation of Straw Tube Performance

November 25, 2014 7 Sedigheh Jowzaee Pure Argon Argon+ 30% CO2 10% 2% 1% 20% 10% 20% Pure Ar 50% Ar+75% CO2

Drift velocity Townsend

  • Garfield 7.40: program for the detailed simulation of gas detectors
  • Simulation of transport properties of electrons and ions with Magboltz 7, 8.9.5
  • Gas mixture 90% Ar, 10% CO2
  • Excellent for high-rate experiments (low aging)
  • Temperature 300 K, absolute pressure 2 atm
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SLIDE 8

No Penning transfer Full Penning transfer Agreement with 34% Penning transfer rate

  • 3. Simulation of Straw Tube Performance

November 25, 2014 8 Sedigheh Jowzaee

Gas Gain Simulation

The gain curve with 0%, 20%, 34%, 40%, 60% and 100% Penning rate Comparison the measured gain with Diethorn’s formula

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SLIDE 9
  • 3. Simulation of Straw Tube Performance

November 25, 2014 9 Sedigheh Jowzaee

Front-end Electronics of Straw

  • The first prototype new front-end chip
  • Preamplifier with variable gain
  • CR-RC2 with variable Tpeak
  • Tail-cancelation with 2 variable time constants
  • Baseline stabilizer
  • Leading edge discriminator for timing
  • Buffered analog output
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SLIDE 10
  • 3. Simulation of Straw Tube Performance

November 25, 2014 10 Sedigheh Jowzaee

TOT spectra measured with 55Fe source show good agreement with simulation for HV 1750 V and threshold based on 10% primary ionization

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SLIDE 11
  • 4. PID with Straw Tubes

November 25, 2014 11 Sedigheh Jowzaee

  • PID based on dE/dx: TOT ? Q
  • Response of 24 single straws to 400 tracks
  • Set the low threshold for high position resolution
  • Correction to distance dependence
  • Truncated average for 24 straw layers

Straw Tracks

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SLIDE 12
  • 4. PID with Straw Tubes

November 25, 2014 12 Sedigheh Jowzaee

Single straws response for 0.7 GeV/c particles before distance correction After distance correction After truncated average by removing 30% of the highest numbers Reasonable for PID

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SLIDE 13
  • 4. PID with Straw Tubes

November 25, 2014 13 Sedigheh Jowzaee

Separation power for p-π, p-K and π-K pairs based on TOT (■) and charge (▲)

  • measurement. The threshold level was set based on 10% primary ionization

2 / ) ( ) ( ) ( ) , (

B A

B Mean A Mean B A Separation     

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SLIDE 14
  • Strangeness physics study
  • Λ-hyperon study in pp→ pK+Λ reaction
  • Strange quark does not exist in nucleon as a constituent
  • How they create and how they interact
  • Theoretical description of the reaction by strange and non strange meson

exchange

  • Analysis different physical effects involved to the reaction
  • N*-resonances
  • YN interaction
  • NΣ cusp effect (NΣ –pΛ couple channel effect)
  • 5. COSY-TOF Experiment

November 25, 2014 14 Sedigheh Jowzaee

COSY-TOF Program

N N K N Λ K N N K Λ N π N*

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SLIDE 15
  • 5. COSY-TOF Experiment

Λ K+ π- p p

  • COSY-TOF detector is Excellent for

strangeness study

  • Upgraded with STT for tracking
  • Large acceptance
  • High statistics measurement
  • Beam momentum= 2.95 GeV/c
  • Polarization (87.5 ± 2.0)%
  • Reconstruction of events with STT
  • 140 µm spatial resolution
  • 130000 reconstructed events

November 25, 2014 15 Sedigheh Jowzaee

COSY-TOF Detector

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SLIDE 16
  • 5. COSY-TOF Experiment

November 25, 2014 16 Sedigheh Jowzaee

STT Calibration

  • Reconstruction of pK+Λ events with STT→ precise calibration
  • Calibration steps
  • TDC correction
  • Multiple hits removal , Signal width cut, Electronics offset correction
  • Estimation of correlation between drift time and radius
  • Straw double layers geometrical position correction
  • Spatial resolution determination
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SLIDE 17
  • 6. Data analysis of pp→pK+Λ reaction
  • pK+Λ event selection criteria
  • Χ2/ndf of kinematic fit < 5
  • z-component of Ʌ decay vertex > 3 cm
  • angle between Ʌ and its decay proton

> 2°

November 25, 2014 17 Sedigheh Jowzaee

Emiss=Einit-(Ep+EK+EΛ)

  • 20 % reconstruction efficiency with

MC simulation

  • Invariant mass resolution 1 MeV/c2

with STT → 3 times better than the old setup without STT

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SLIDE 18

MC Exp

  • 6. Data analysis of pp→pK+Λ reaction

November 25, 2014 18 Sedigheh Jowzaee

  • The experiment covers kinematically complete phase space
  • Strong deviations from homogenous distribution over phase space
  • Strong enhancements seen on the left and center

Dalitz Plot Analysis

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SLIDE 19
  • 6. Data analysis of pp→pK+Λ reaction
  • Interference between physical

effects in KΛ and pΛ subsystems

  • Nucleon excited states (N*-resonances)
  • NΛ interaction (pΛ-FSI )
  • NΣ-pΛ coupled channel effect (NΣ cusp)

November 25, 2014 19 Sedigheh Jowzaee

Dalitz Plot Analysis

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SLIDE 20
  • 6. Data analysis of pp→pK+Λ reaction

November 25, 2014 20 Sedigheh Jowzaee

  • Dividing the Dalitz

plot into three equal phase space volume regions in pΛ channel with Helicity angle cosθpK in pΛ rest frame

  • m2

pΛ distribution at

upper region of Dalitz plot is significantly less than other regions

  • Interference with
  • ther physical effects

including N* resonances

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SLIDE 21
  • 6. Data analysis of pp→pK+Λ reaction

November 25, 2014 21 Sedigheh Jowzaee

  • Cusp effect is stronger at lower

parts of the Dalitz plot

  • pΛ-FSI effect seems to be same in

three parts in the low enough range

  • f the mpΛ
  • Cusp effect fitted with

two Breit-Wigner functions

  • Shape of the cusp is

different in three sections

  • No theoretical

description of cusp in pΛ channel

pΛ Invariant Mass Analysis

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SLIDE 22
  • 6. Data analysis of pp→pK+Λ reaction

November 25, 2014 22 Sedigheh Jowzaee

Cusp Effect Angular Distribution

  • The cusp angular distribution is
  • btained by subtraction the

background from the cusp effect

  • The cusp effect study is limited to

the range of 2.11 to 2.18 MeV/c2 in pΛ subsystem

  • The distributions are fitted with

Legendre polynomial functions

  • NΣ cusp angular distribution is

symmetric and has a dominant S- wave contribution

      

4 2 2 1 2 2 2

5 2 cos cos ) (cos ) (cos cos p p p P a P a d d

cms K cusp

    

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SLIDE 23
  • 6. Data analysis of pp→pK+Λ reaction

November 25, 2014 23 Sedigheh Jowzaee

Particles Angular Distribution in Helicity Frame

  • In 1 + 2 → a + b + c reaction the Helicity

angle is the angle between particle (a) and b or c in the {bc} rest frame

  • Physical effects in the Dalitz plot

can be seen in Helicity angle distributions

  • The N*(1650) and N*(1720) resonances

introduces an asymmetry with enhancement at cosθRpΛ

Kp = -1

  • The pΛ-FSI enhances the distributions

towards cosθRKΛ

pK = -1 and cosθRpK Λp = 1

  • No structure for cusp due to its dominant

S-wave contribution

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SLIDE 24
  • 6. Data analysis of pp→pK+Λ reaction

November 25, 2014 24 Sedigheh Jowzaee

Particles Angular Distribution in CMS

  • The angular distributions in the CMS are

symmetric due to the identical particles in the entrance channel

  • Some asymmetries are seen in the

forward and backward regions

  • Incomplete MC description of the

detector at small angles

  • Angular distributions described by

Legendre polynomials

... cos cos ) (cos ) (        

   

4 2 2 1 2

1 2 C C C P a l d d

l l l

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SLIDE 25
  • 6. Data analysis of pp→pK+Λ reaction
  • Interference between different l-values can be seen in the analyzing power distribution
  • At pbeam = 2.95 GeV/c the (S,P) and (S,D)-wave interference contributions can be seen
  • The analyzing power distribution is fit using the associated Legendre polynomial

functions

  • The kaon analyzing power is more symmetric for higher mpΛ invariant masses

November 25, 2014 Sedigheh Jowzaee 25

Kaon Analyzing Power

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SLIDE 26
  • 6. Data analysis of pp→pK+Λ reaction
  • The (S,D) contribution decrease with increasing mpΛ
  • The (S,P) contribution for low mpΛ is non zero with 2σ confidence
  • The (S,P) contribution of the kaon for low mpΛ where the {pΛ} system is in S-wave can be

used to extract the pΛ spin-triplet scattering length from the pΛ final state interaction

November 25, 2014 Sedigheh Jowzaee 26

Kaon Analyzing Power

) (cos ) (cos ... sin ) , ( sin     

1 2 1 1 2

2 P P D P S D S Ιm θ Ιm(S,P) A N       

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SLIDE 27
  • 6. Data analysis of pp→pK+Λ reaction
  • There is a symmetric behavior
  • The analyzing power of the proton decreases toward zero with increasing mKΛ
  • A complete explanation needs the partial wave analysis

November 25, 2014 Sedigheh Jowzaee 27

Proton Analyzing Power

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SLIDE 28
  • 6. Data analysis of pp→pK+Λ reaction

November 25, 2014 28 Sedigheh Jowzaee

Lambda Analyzing Power

  • Both the (S,P) and (S,D) contributions are dominant
  • The analyzing power of lambda significantly decreases with increasing the mKp
  • A complete explanation needs the partial wave analysis
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SLIDE 29

Summary

  • Modular straw tube tracker is a good tool for tracking and particles identification in large scale

experiments like the COSY-TOF and the PANDA

  • PID with TOT and integrated charge information present similar performance for the STT
  • The pΛ invariant mass resolution of 1MeV/c2 obtained due to the STT performance in the COSY-

TOF detector is good enough to study the NΣ cusp and pΛ-FSI effects in the pp → pK+Λ reaction

  • Division of Dalitz plot in the Helicity angle is helpful to study the NΣ cusp effect
  • Cusp angular distribution is same between different region of the Dalitz plot
  • Angular distributions of the particles in the CMS frame is symmetric as expected
  • Analyzing power of proton is more symmetric compared to the kaon and lambda

November 25, 2014 29 Sedigheh Jowzaee

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SLIDE 30

Thank you

I NTERNATI ONAL PHD PROJECTS I N APPLI ED NUCLEAR PHYSI CS AND I NNOVATI VE TECHNOLOGI ES

This project is supported by the Foundation for Polish Science – M PD program, co-financed by the European Union within the European Regional Development Fund

November 25, 2014 30 Sedigheh Jowzaee