Particle Identification@PANDA: Recipes and Physics Applications Concettina Sfienti, GSI Darmstadt Hypernuclear Physics Double Hypernuclei in PANDA Particle IDentification in PANDA Cherenkov R&D Conclusions & Outlook XII International Conference on Hadron Spectroscopy 8-13 October 2007, INFN- Laboratori Nazionali di Frascati, Frascati (Roma) - Italy

Baryon-Baryon Interaction Takahashi et al. 1963: Danysz et al. 10LLBe 1966: Prowse 6LLHe 1991: KEK-E176 13 LLB 2001: KEK-E373 6LLHe 2001: AGS-E906 4LLH (~15) Hypernuclear Physics

Strange baryons in nuclear systems S=1: L-, S-hypernuclei nuclear structure, new symmetries The presence of a hyperon may modify the size, shape… of nuclei New specific symmetries hyperon-nucleon interaction strange baryons in nuclei weak decay S=2: X-atoms, X-, 2L-hypernuclei nuclear structure baryon-baryon interaction in SU(3)f H-dibaryon S=3: W-atom, (W-,LX-,3L-hypernuclei) Hypernuclear Physics

Birth, Life and Death of a Hypernucleus target nucleus p,n  L g electromagnetic decays nonmesonic weak decay mesonic decays hadronic decay in emulsion strangeness deposition FINUDA strangeness production (p+, K+), (p-, K0) BNL,KEK,(GSI) strangeness exchange (K_, p-) ,(K_, p0) BNL,KEK,JPARC electroproduction (e,e´K+) , (g,K+) Jlab, MAMI-C Required energy resolution K,p: 1-2 MeV Kstopped: 1 MeV e: 0.5 MeV g-transitions: 5 keV Hypernuclear Physics

Production of LL-Hypernuclei simultaneous implantation of two L is not feasible reaction with lowest Q-value: X-pLL: 28MeV direct implantation of a X- via a two-body reaction difficult because of large momentum transfer X- capture: X- p  LL + 28 MeV X- L +28MeV g in most cases two-step process production of X- in primary nucleus slowing down and capture in a secondary target nucleus spectroscopic studies only possible via the decay products Double Hypernuclei in PANDA

Production of X- X- production PANDA@HESR X- conversion in 2 L: p(K-,K+)X- needs K- beam (c·t=3.7cm) recoil momentum >460 MeV/c KEK-E176: 102  E373: 103 stopped X per week AGS-E885: 104 PANDA@HESR X- capture: X- p  LL + 28 MeV X- 3 GeV/c Kaons _ X L trigger p +28MeV g few times 105 stopped X per day  g-spectroscopy feasible Double Hypernuclei in PANDA

Strategy Universal detector for high luminosity tag primary reaction by X+ or 2K+ in forward direction  trigger measure incoming track of X- by active secondary target  reduce BG measure emitted g-rays with high resolution  spectroscopy Antiproton momentum close to threshold (3GeV/c) only few open channels with double strangeness production: Low mass secondary targets (Li,Be,B,C) in four separated sections identification can rely on existing information on single hypernuclei low g-ray absorption no x-ray background  B Li Be C Double Hypernuclei in PANDA

Integration in the Setup θlab < 45° X+, K trigger θlab = 45°-90°, X- capture , Hypernucleus formation θlab > 90°, g-detection at backward angles Neutron background (16000 n s-1 per HPGe Crystal ) Der polarwinkel theta. Der nachweiss des antihyperon und seine assoziierten kaonen erfolgt unter dem winkelbereich von 0-45grad. 2. Geschieht zwischen 45-90 3. Wird bei ruckswartswinkeln nachgewiesen wo der hadronische untergrund geringer ist. The PANDA Detector

PANDA Spectrometer Muon Detectors Forward RICH Barrel DIRC Barrel TOF Endcap DIRC Forward TOF The PANDA Detector

Particle Identification dE/dX by TPC PANDA PID Requirements: Particle identification essential for PANDA Momentum range 200 MeV/c – 10 GeV/c Different process for PID needed PID Processes: Cherenkov radiation: above 1 GeV Radiators: quartz, aerogel, C4F10 Energy loss: below 1 GeV Best accuracy with TPC Time of flight Start detector: fibre detector Electromagnetic showers: EMC for e and γ Forward ToF Particle IDentification in PANDA

Detection of Internally Reflected Cherenkov light A Textbook Example: the BABAR DIRC Detection of Internally Reflected Cherenkov light Different Cherenkov angles give different reflection angles The task is to separate p’s and K’s in the range: 0.7<p< 3.5 GeV/c The Barrel DIRC Measure angle of Cherenkov cone Transmitted by internal reflection (typ. # light bounces = 300) Detected by PMTs

A Textbook Example: the BABAR DIRC The Barrel DIRC

The Barrel DIRC@PANDA (I) Babar Design for PANDA 96 Fused silica bars, 2.6m length Water tank & 7000 PMTs K eff. K eff. Fulfills physics requirements... Number of required photon detectors Water tank Overall size of DIRC Bar-size uncertainties Chromatic uncertainty  miss-id.  miss-id. The Barrel DIRC

The Barrel DIRC@PANDA (II) Smaller sized photon-detector with focusing optics: Get rid of water tank with different imaging (reduced background, maintenance) Focusing removes bar-size uncertainty in the focusing plane: Improved geometrical (Cherenkov angle) resolution Smaller detectors have better transit time spread Improved timing resolution (sDt = 100 .. 200 ps) Reduces chromatic uncertainty The Barrel DIRC

3D imaging X-Y and TOP [B. Ratcliff NIMA502(2003)211] Ultimate Focusing-TOP DIRC (t) 3D imaging X-Y and TOP [B. Ratcliff NIMA502(2003)211] X proximity focusing with wide bar Y focused by mirror Time-Of-Propagation Measurement A.Lehmann, Erlangen 2006 Photodetector requirements.... DT < 100ps DY~1-2 mm DX ~ 5 mm Single photon counting Efficiency (QE, gain, S/N) > 20% Magnetic field immunity 1.5T Effective area > 70% Operational Lifetime The Barrel DIRC

Quick summary on ongoing activities Many sub projects have started Radiator radiation hardness surface polishing Photon detector Gain and time resolution tests Coupling to radiator Three forward-endcap Cherenkov options Focussing disk (x-y image) TOP disk (x-t image) Proximity Imaging RICH liquid radiator + CsJ-photon det. tracking capabilities R&D around the DIRCs

….more about PID Detectors Central Tracker: TPC option Goal dp/p ~1% dE/dx resolution ~6% Challenges Space charge build-up Continuous sampling Particle IDentification in PANDA

Conclusions & Outlook Antiproton collisions with nuclei offer many opportunities to study strange baryon in cold nuclei Baryon-baryon interaction Weak decay Spectroscopy of baryonic atoms .... These studies are made possible by a unique combination of experimental facilities at FAIR  spectroscopy with Ge detectors  PANDA  antiproton beams Particle identification (PID) is an essential requirement for such a unique physics program. The DIRC detectors will play a key role A wide R&D program is ongoing Conclusions & Outlook

The PANDA Collaboration www-panda.gsi.de Conclusions & Outlook

….more about PID Detectors EMC Barrel and Endcaps Approx 16000 crystals LAAPDs readout Challenges High rate capability: 2 x 107 interactions/s High resolution & low threshold (10 MeV) Compact design: EMC inside solenoid Operation in magnetic field of ~ 2T Proto60 Particle IDentification in PANDA

….more about PID Detectors Central Tracker: ST option Total number of tubes - ~5000 Radial dimensions – 16-42cm Length – 1.5m Tube diameters – 10mm Tube wall material – Mylar, 30μm Anode wire – W/Re, 20μm Spatial resolution – σrφ≈150μm, σz≈3-10mm Gas filling – Ar+10%CO2 Gas absolute pressure – 2 bar Thickness - ~1% X0. more details in T. Stockmanns talk Particle IDentification in PANDA

….more about PID Detectors TOF system Low momentum kaons Scintillator fibers (START) ~2000 fibers placed in two rings  Readout with SiPMT Tof barrel (STOP) Time Resolution ~ 80ps 16 Slabs ~6 bars Particle IDentification in PANDA