HADES investigating in-medium hadron properties at FAIR

1. HADES investigating in-medium hadron properties at FAIR Andrej Kugler for the HADES collaboration PANIC, August 28, 2014, Hamburg

2. Outline • Motivation • Present status • HADES setup • Dileptons from pp, pA and AA collisions at SIS18 • Hadrons production • HADES at FAIR • Physics motivation for ECAL • Simulations of ECAL • Calorimeter module • Module + PMT’s tests • LED driven control /calibration • Front-end electronics • Summary

3. Baryonic matter at SIS Beam Energy Evolution of average rB Compositionof a hotpDNgas Elab=30GeV g* g* g* Rapp, Wambach, Adv.Nucl.Phys. 25 (2000) Elab=11GeV l+ l+ l+ Elab=2GeV l- l- l- t >10 fm/c K,L,f,X, • Moderate densities but long lifetime: • max/r0 = 1-3, T<80 MeV, ~15fm/c • Baryon dominated: • p densities a factor ~10 lower as compared to SPS regime! • Matter enriched by baryonic resonances (~30%), N/Apart ≈ 10% HADES Rare and penetrating probes

4. High Acceptance Di-Electron Spectrometer • HADES strategy: • Systematic di-electron and strangeness measurements in NN, AA, pA, pN and pA collisions Recorded data sets sw = 15 MeV/c2 • Beams provided by SIS18: p, p, ions • Full azimuthal coverage • Hadron and lepton identification • e+e- pair acceptance 0.35 • Mass resolution 2 % (/ region) • ~ 80.000 channels • now: up to 50 kHz event rate (400 Mbyte/s peak data rate)

5. Side View START FW High Acceptance Di-Electron Spectrometer Particle identification by means of: e- e+ p+ p- dE/dx in the MDC and ToF p Velocity vs. momentum K+ d,4He 3He RPC Operational at GSI since 2002 Upgrade 2008 – 2010 t RICH rings Vertex reconstruction

6. Dileptons: Excess above eta contribution Phys. Lett. B 663(2008)43 • Normalization: Np0 = ½ (Np+ + Np-),±from the same data sample • Systematic errors: ~25%, sM(w) = 9% • “hadronic cocktail”: thermal source,only long-lived components included,i.e. p0, h: TAPS data, w: m scaling.R. Averbeck et. al. PRC 67 (2003) 024903 • I. Froehlich et al.,arXiv:0708.2382 • HADES:EuroPhys.Journal A40, 45 (2009)] Phys. Rev. C84(2011)014902 Phys.Rev. Lett 98(2007) 052302

7. Dileptons: Excess above eta contribution  contribution subtracted e+e- excess @ 1-2 AGeV • Excess above reference NN and Mee > 150 MeV/c2 increases from ~0 (light systems) to ~3 (ArKcl) and ~8-10 in Au-Au . Precise measurement of NN (np. and pp) reference was an essential input ! • Excess yield scales with system size ~ Apart1.4  multistep processes? • Rapid increase of relative yield reflects the number of ‘s/ N*’s regenerated in fireball with life time ~10 fm/c

8. Hadronproduction in 1.23 AGeVAu+Au collisions • First measurements at such low beam energy! K- HADES Preliminary HADES Preliminary K0s f √s-√sth = -0.44 GeV L HADES Preliminary HADES Preliminary Far below NN production thresholdStrong constraints on production mechanism!

9. Hades and the phase diagram of QCD matter Extracted (T, mb) fit in the systematics of the SHM • -- THERMUS fit: J.Cleymans, J.Phys.G31(2005)S1069 • HADES Au+Au data at 1.25 AGeV PRELIMINARY,Ar+KCl: Phys.Rev.C80:025209,2009 Thermal equilibrium also at low energies (high mB)? Thermal vs. chemical equilibrium?

10. Pion-nucleus – on line spectra (July 2014) K+K- Mesons – π+π- decay bayons – pπ- decays • measurement combined with machine developments for SIS100 • (1/3 below space chargé limit of SIS18)

11. 2018 - HADES at new FAIR facility SIS100 : HADES and CBM, beam energies up to 11 A GeV for Au • Emissivity of hot/dense nuclear matter • Spectral functions of r/w in dense (baryon dominated) hadronic matter • Multi-strange particle and lepton pair excitation functions • Charm production in proton induced reactions SIS300 : CBM, beam energies up to 35 A GeV for Au • Full exploitation of rare probes a highest mB; fluctuations, flow HADES CBM

12. HADES at SIS100: phase space coverage for e+e- Ebeam = 1 GeV/u • overall acceptance for di-electron pairs Acc ≈ 35% • with nice mid-rapidity coverage yCM yCM yCM Ebeam = 8 GeV/u • Acc ≈ 20% • shift towards backward rapidity (complementary to CBM detector) Ebeam = 11 GeV/u •  Acc ≈ 20%

13. HADES at SIS100: problems, challenges, opportunities • Challenge: limited granularity  • sophisticated tracking algorithm • Au+Au1.23 GeV/usuccessfully measured in May 2012 • Ni+Ni8 GeV/u ≈ Au+Au at 1.23 GeV/u • Au+Au4GeV/u occupancy increases by factor of 2! Au+Au 4 GeV/u Event display Au+Au 4 GeV/u Occupancy in tracking chambers (bmax= 1 fm) Cell size is factor of 2 larger y – radial coordinate in drift chamber

14. Feasibility studies: Au+Au at 4 GeV/u Track reconstruction efficiency K+ L High reconstruction efficiency is required for rejection of conversion pairs Mass vs. momentum distributions K- K0s

15. HADES physicsprogram@FAIR p+p 3.5 GeV • High Acceptance DiElectronSpectrometer • studies in-medium modifications by measuring dielectrons • strangeness measurements ϕ, K+/-,  Ξ(1321) … • We studied proton, pion and nucleus induced reactions at SIS18/Bevalac energies and plan to continue these studies at SIS100 EPJA-101842.R1 (2012) Comparison of pA with pp scaled according to Glauber model PhysicsLetters B 715 (2012) 304–309

16. Electromagnetic Calorimeter ECAL • For lepton pair excess determination a precise knowledge of the hadronic cocktail is needed • (particle yields at chemical freeze-out) • At 2-40 AGeV mainly dominated by η-Dalitz • Normalization to π0 (at SIS18 – TAPS data) • No data at 2-10 GeV ! •  Calorimeter for HADES •  π0, η measurement •  improved pion suppression Almost no data on inclusive production at 2-10 GeV even in p+p reactions !

17. Calorimeter module • Glass properties: • chemical composition: • SiO2 -39%,PbO – 55%, K2O - 2%, Na2O – 3%) • density: 4.o6 g/cm3 • radiation length (X0): 2.51 cm • refractive index: 1.708 (at 400 nm) • Moliére radius: 3.6 cm • totally needed 978 pieces • lead glass on loan from end cap calorimeter of OPAL experiment • lead glass type: CEREN 25 • dimensions 92x92x420 mm • wrapped in TYVEK paper • brass can 0.45 mm thick 1inch Ham. 1.5 inch EMI 9903KB 650 pieces from MIRAC experiment (WA98 hadron calorimeter) 3inch Ham.

18. Test with Photon Beam at Mainz • used tagger to select 8 known gamma energies • 8 different trigger signals – 8 energies measured in one measurement • beam collimated by Ø 2 mm lead collimator placed 1.5 meters upstream • beam size in front of the modules ~ 6 mm

19. Relative energy resolution Energy resolution behind the names of modules is for 1 GeV photon... 1inch Ham. Resolution [%] 1.5inch EMI PRELIMINARY 3inch Ham. measured with CAEN ADC, signal shaped by MA8000 shaper

20. Energy leakage into neighbour module I rotated by 12° rotated by 6° Sum of triggers 27 mm from junction Sum of triggers 27 mm from junction Sum of triggers 27 mm from junction Measured in January 2014 Used 3 inch PMT

21. Energy leakage into neighbour module II Sum of deposited energy in VH3and VH6 modules Deposited energy in VH3module 1218 MeV PRELIMINARY Measured in January 2014 Used 3 inch PMT

22. LED light system for calibration and stability monitoring LED based system is being developed for calibration and stability monitoring of ECAL modules First prototype (6/2012) Fiber to lead glass transition Second prototype (3/2013)

23. Simulation of the ECAL setup • implemented in HGeant code (GEANT3 based framework of HADES collaboration) • simulation of lead glass response split to: • shower development in a module • transport of the Cherenkov photons • look-up table approach used for Cherenkov photon to fasten the calculation Diphoton invariant mass spectra in Ni+Ni@ 8 GeV Module occupancy in Ni+Ni @ 8GeV M = 555 MeV/c2 σ = 37 MeV/c2 S/B ~ 1%

24. Time schedule for ECAL project Status May 2013

25. Summary of ECAL project • Motivation: • Improved dilepton spectroscopy by HADES – lepton and photon pairs at the same time • Current status: • ~150 modules assembled, ~70 modules measured in detail • 1.5 and 3 inch photomultipliers successfully tested, usage of 1 inch photomultiplier is under investigation • Mechanical construction designed, simulations performed, software for read-out prepared • prototype of LED based monitoring system proven • two novel solutions for front-end electronic under development • TDR updated and submitted to FAIR management • Plans: • Finish front-end electronic development • Repeat tests in beam with this electronic • Build the detector

26. FAIR@Darmstadt, Germany SIS 100/300 SIS 18 UNILAC CBM Super FRS HESR • ECAL detector • planned for SIS 100 • 978 modules of lead glass + photomultiplier • polar angle 12° - 45° • novel electronic for read out • HADES setup • installed at GSI SIS 18 • six identical sectors • almost full azimuthal angle • polar angle 18° - 85° • high rate counting CR CBM • 2012-2018 • Module 0:Heavy-Ion Synchrotron SIS100 • Module 1:HADES/CBM, APPA, and detectorcalibration. FLAIR • 2013-2018 • Module 2:Super-FRS →RIB forNUSTAR. • Module 3:Antiproton facilityfor PANDA RESR 100 m NESR HADES

27. The HADES Collaboration 18 institution partners ~100 collaborators

28. Backup slides

29. HADES: Au+Au 1.23 AGeV KaoS: Au+Au 1.5 AGeV FOPI: Ni+Ni1.91 AGeV Azimuthal angular distributions of Kaons K+ K+ K+ K+ HADES Preliminary FOPI collab., arXiv: 1403.1504v2 [nucl-ex] KaoS data: Ph.D. thesis A.Forster Fitted with: f(F)=1+2v1*cos(F)+2v2*cos(2F))F= FK+– FRP • Far subthresholdproduced kaons highly sensitive to collective effects • Statistics is clearly improved! • K- measured for the first time!  flow analysis • HADES data complementary to FOPI and KaoS results • will further constrain model calculations

30. pion beamsat SIS18 • For physics discussed in this talk: • single pion, + - production : coupling of  to baryon resonances • our knowledge (PDG) on BR(R->N) • 1.3 <s <2 is based on 240 000 events (differential; distributions not avialable) • needed for PWA and coupled channel calculations • e+e- never measured from pion induced reactions • Resonance Dalitz decays RNe+e- • strangeness production of nucleus : K , K0 ,  • Secondary beams (C+Be, N+Be,..) - beams with I ~ 106/s • p  (0.7-2 GeV/c) : Access to second/third resonance region • 2.0> s>1.6 GeV • Pion momentum p/p =4% : in beam tracking system: • (X1,X2-Y3) for pion mometnum determination : p/p =0.1%

31. ECAL Module tests Al vs. Mylar vs. TYVEK Tests of EMI photomultipliers • 720 PMTs tested • ~650 can be used TYVEK paper 1060B gives the best resolution • PMT alone at HV=1500 and 1700 V • PMT with small scintillator and gamma-source 22Na at HV=1200, 1500, and 1700 V

32. ECAL Module tests E= 1399MeV E= 1210MeV ALL Beam test at Mainz Purpose: measure the energy resolution of detector modules with various configurations in g beam at energy 0-1500 MeV Trigger: OR of signals from 8 selected scintillators in electron tagger – giving events with 8 known gamma energies in range from 0 to energy of the electron beam E= 831MeV E= 676MeV E= 1021MeV Counts [-] E= 72.1MeV E= 452MeV E= 261MeV Measured in Sep 2009 Used EMI photomultipliers ADC channel Ee=1508 MeV, g energy spread <= 1%

33. ECAL Module tests Beam test at CERN – PS synchrotron – T10 beam line Purpose: evaluate electron/pion separation and measure time resolution Used: secondary π- beam of 0.4 – 6 GeV/c with admixture of e- e-/p- separation factor • Measured: • time resolution of 215 ps for 800 MeV e- • energy resolution 6.9% for 1 GeV e- • (worse than expected 6% based on g measurement…caused mainly by tailing of e- peaks) Measured in May 2010 Used EMI photomultipliers

34. ECAL Module tests Quality control by exploiting Cosmicmuons 1.5 inch photomultiplier (EMI 9903KB) Same shaper (shaper calibration not included!)

35. ECAL Module tests Setup for measurement with cosmic muons • Cosmic muons: • energy ~ 2 GeV • energy deposit in module ~ 200 MeV • Cherenkov light output corresponds to ~ 577 MeV electrons • count rate ~20 particles / hour • two such setups currently available, third is under construction • all assembled modules will be calibrated using cosmic muons

36. ECAL Module PMT’s tests Photomultiplier comparison on cosmics 1.5 inch EMI 9903KB 3 inch Hamamatsu R6091 1 inch Hamamatsu R8619 Need to be further tested! ADC (channels) ADC (channels) • very expensive • energy resolution: 8.0% (best case up to now) • not better than EMI (unexpected) • standard used • not enough pieces • energy resolution: 6.7 % (best case) • only a few first tests performed • energy resolution: 9% (very preliminary!!) • need to prove, if worse resolution is acceptable • significantly lower price (1/3 of 3 inch Hamamatsu)

37. Electronics Detector response & requirements on electronics

38. Electronic test Gain linearity of the electronics Electronic tests using LED system Energy resolution LED system is very useful for detector development – fast test of all the chain PMTs+divider+frond-end board

39. LED system Measurement with LED diode -very fast measurement (kHz) in comparison with cosmics muons - signal from LED pulser set to get the same detector response as from cosmic muons 1.5 inch photomultiplier (EMI 9903KB) Yellow curve – detector output Green curve – diode input (second peak is reflection on diode) LED

40. Electronics Front-end electronic – Cracow design • 8 input channels • Signal split into two paths: • Fast path: fast discriminator for time measurement • Slow path: signal integrated for amplitude measurement • Differential LVDS output • Discriminator threshold for each channel via slow control lines • ADC and TDC done by TRBv3boards Time signal TDC Threshold setup Amplitude signal ADC ±5 GND Inputs • Different shaping time and gain tested • Energy resolution with pulser: 0.6% at 100 ps time precision • Energy resolution with LED-PMT signal: 3.6% at 150 ps time precision

41. Electronics Charge measurement with FPGA • Idea: Modified Wilkinson ADC • Integrate input signal with a capacitor • Discharge via current source -> fast crossing of zero • Q2W: Measure time to reach zero ~Q using an FPGA-TDC • COME & KISS design: keep it small and simple by using complex commercial elements Q2W prototype

42. Electronics New PADIWA-AMPS1 layout with Q2W (topside) Delivery end of September 2013