Identification of Charged Particles in Straw Tube Detectors INTERNATIONAL PHD PROJECTS IN APPLIED NUCLEAR PHYSICS AND INNOVATIVE TECHNOLOGIES This project is supported by the Foundation for Polish Science – MPD program, co-financed by the European Union within the European Regional Development Fund Identification of Charged Particles in Straw Tube Detectors Sedigheh Jowzaee Jagiellonian University MESON2012 Conference, Krakow, Poland, 31May-5June 2012

Outline PANDA experiment Straw Tube Tracker Straw tube simulation Straw front-end electronic PID Methods Separation π-K-p Summary

1. PANDA Experiment PANDA Program Nuclear Target Interaction of antiproton with momentum range (1.5-15 GeV/c) Hydrogen Target Charmonium spectroscopy Exotic hadrons (hybrids, glueballs, multi-quark states) Strange and charmed baryons Structure of the nucleon Nuclear Target Hadron properties in the nuclear medium γ -ray spectroscopy of hypernuclei Two-body thresholds Molecules, Multiquarks Hybrids Glueballs qq̄ Mesons

1. PANDA Experiment PANDA (antiProton Annihilation at Darmstdat) Detector Full angular acceptance and angular resolution Particle Identification (p,π,K, e, μ) in the range up to ~ 8 GeV/c High momentum resolution Target spectrometer Forward spectrometer

2. Straw Tube Tracker STT layout FST layout 4636 straw in 2 semi-barrels around beam/target pipe 23-27 planar layers in 6 hexagonal sectors Length: 1500 mm+150 mm (read-out) Angular acceptance: near 4π FST layout 10752 straw tubes 6 tracking station: 2 before, 2 inside and 2 after the dipole magnet 4 double layers per tracking station Angular acceptance: ±5̊ vertically, ±10̊ horizontally

2. Straw Tube Tracker Straw tube structure Advantages of straws Al-mylar tube, 29 μm thick, Ø=10 mm Gold-plated anode, Ø=20 μm End plug (ABS thermo-plastic) Crimp pin (Cu, gold-plated) Gas tube (PVC med, 150 μm wall) 2.5 g weight per tube Advantages of straws Modules (easy to exchange, high flexibility) Low mass (self supporting by gas overpressure ) High rates (1 MHz/wire) Low ageing Fast readout (pulse shaping and digitalization)

3. Straw Tube Simulation Garfield 9: program for the detailed simulation of gas detectors Simulation of transport properties of electrons and ions with new version Magboltz 8.9.5 Gas mixture: 90% Ar, 10% CO2 (the best gas mixture for high-rate, no polymeric reactions ) Temperature 300 K, absolute pressure 2 atm Drift velocity Townsend Pure Ar Argon+ 30% CO2 10% 20% 20% 10% 50% 2% 1% Ar+75% CO2 Pure Argon

3. Straw Tube Simulation Gas gain simulation Full penning transfer Agreement with 34% penning rate No penning transfer The gain curve with 0%, 20%, 30%, 40%, 60% and 100% Penning rate Comparison the measured gain with Diethorn’s formula

4. Straw Front-end Electronic The first prototype new front-end chip fabricated in AMS 0.35 µm technology 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

4. Straw Front-end Electronic The ASIC test-board v. 2 Each ASIC includes 4 channels Digital LVDS & Buffered analog outputs Flash program memory ATMega controller for ASIC parameters (gain, shaping) Baseline and threshold set with external voltage source Optimum configuration

4. Straw Front-end Electronic The transfer function Transfer function produced by injection of “delta like” pulse to front-end The 55Fe pulse convoluted by transfer function

4. Straw Front-end Electronic The high-rate test Minimum ionizing proton beam of the intensity 1.2 MHz/straw signals were recorded by means of fast sampling ADC in long window of 5μs Baseline keeps always stable Energy resolution of the straws would not be affected in high counting rates

5. PID Methods TOT ? Q Energy loss: below 1 GeV PID based on dE/dx: Straw Tube Tracker (STT)

5. PID Methods TOT simulation Response of 24 single straws to 400 tracks Set the threshold as low as possible for high position resolution Correction to distance dependence Truncated average for 24 straw layers Straw Tracks

5. PID Methods 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

5. PID Methods TOT spectra measured with 55Fe source shows good agreement with simulation for HV 1750 V and threshold based on 20 primary electrons

5. PID Methods TOT vs. input charge plot shows good agreement between simulation and test with 55Fe source For high input charges, the measured TOT deviates from simulations due to saturation of pulses in the shaper

6. Separation p-K-π Separation power for p-π, p-K and π-K pairs based on TOT (■) and charge (▲) measurement. The threshold level was set based on 20 primary electrons

6. Separation p-K-π 0.3 GeV/c ● proton ● kaon ● pion 0.7 GeV/c ● proton ● kaon ● pion The separation power for K-π and p-K pairs calculated using TOT and Q are different due to saturation of TOT as a function of Q for high energy deposits in the straws Saturation leads to smaller relative smearing and lower difference of the corresponding mean values of TOT than Q

6. Separation p-K-π The Separation power for π-K pair based on TOT with threshold levels based on 20 and 10 primary electrons and comparison with Q

7. Summary Modular straw tube trackers are good tools for tracking and identification of particles in large scale experiments New front-end chip works very well for straw read-out Distance correction improves the results of TOT and Q for PID The separation power based on the TOT and Q measurements are comparable in the investigated momentum range 0.3-1.0 GeV/c TOT works very well for PID in straw tube trackers

Thank you for your attention Email: sedigheh.jowzaee@uj.edu.pl Thank you for your attention MESON2012 Conference, Krakow, Poland, 31May-5June 2012

5. PID Methods TOT & Drift time simulation for cosmic rays Tot vs. drift time for Muon 1GeV/c passing with 30 degree to wire Drift time spectra for Muon 1GeV/c

6. Position Resolution proton 1 GeV/c threshold based on 20 primary electrons threshold based on 10 primary electrons

1. PANDA Experiment PANDA (antiProton Annihilation at Darmstdat) Detector Full angular acceptance and angular resolution High momentum resolution Particle Identification (p,π,K, e, μ) in the range up to ~ 8 GeV/c

3. Straw Tube Simulation Transverse diffusion Longitudinal diffusion Ar+10% CO2 15% Ar+10% CO2 20% 15% 20% 50% 50% Adding CO2 to Ar is efficient way to reduce the diffusion coefficient

3. Straw Tube Simulation attachment Ionization rate Ar+ 75% CO2 50% 20% 10% CO2 as a quencher for the good drift properties and low ageing Ar is a main component that dominantly ionized

4. Straw Front-end Electronic Different settings of time constants in tail-cancelation and shaping part Optimum configuration based on fast shaping and higher amplitude and lower undershoot