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1 - Onset of deconfinementNA60+ - Existence (or non existence) of QCD critical point - Chiral symmetry restorationMeasuring dimuons at different energies in the range 20-160 AGeV and with different collision systems: Simulation studies for the apparatus setup (PRIN 2009): - acceptances - rec eff - mass resolution - rates1

First order transition and onset of deconfinementFull circles: early stage of systems created in central Pb-Pb collisions at different energies at sNN = 6.3 , 7.6, 8.7 and 12.3 GeV (NA49 PbPb, AGS AuAu)

Systems cool and expand evolving along the solid lines to the freeze-out points (squares and triangles)

The magenta circle might lie on the first order transition line marking the onset of deconfinement QCD phase diagram poorly known in the region of highest baryon densities and moderate temperatures is there a critical point?

Critical point(s) search

Search for the critical pointEnergy interval covered by SPS: fundamental for search of CPRequires a bidimensional scan in energy and collision systemAccelerator landscape Beam conditions: CERN vs. GSI/FAIRLuminosity at the SPS comparable to that of SIS100/300 No losses of beam quality at lower energies except for emittance growth RP limits at CERN in EHN1, not in (former) NA60 cave < 11 35 (45) SPS SIS100/300 beam target interaction intensity thickness rate2.5106 5105 [i ] [Hz] [Hz] 20% NA60 (2003) new injection scheme 108 10% 107 108 1% 106 interaction rate [Hz] 105 - 107Energy range: 10 158 [AGeV] LHC AA 5104 Pb beams scheduled for the SPS in 2016-2017, 2019-2021 H.J.Specht, ECT* Trento 2013

qqCharacteristic regimes in invariant m+m- mass, M2=(pe++ pe- )2 : Drell-Yan: power law ~ Mn thermal ~ exp(-M/T): - QGP - HG (4p processes)Measuring dileptons in the IMR region~ exponential fall-off Planck-like M>1 GeV

fit to T>Tc: partons dominaterange 1.1-2.0 GeV: T=20512 MeV 1.1-2.4 GeV: T=23010 MeV

Evolution of yield and T vs beam energy

QGP spectrum using a lattice-QCD constrained rate (Rapp et al.)hadronic spectrum using the in-medium r+w+4p spectral function (Rapp et al.)PbPb 40 AGeV 0-5% central collisionsQGP fraction still relevant even at 20-40 AGeV?

Measure evolution of yield and temperature vs beam energyIn-In 160 AGeV dNch/dh>30 6

pT spectra nearly thermal

Fit with dN/dpT=pTexp(-MT/T) in 50 MeV mass bins (using 107 ev MC sample) HG radiationQGP radiation

mass spectrum: T = 20512 MeV pT spectra: = 19012 MeV M >1 GeV T = 205 MeV > Tc = 170 (MeV) - Teff independent of mass within errors - same values within errors negligible flow soft EoS above Tc all consistent with partonic phase Transverse momentum spectra: evolution of Teff vs beam energyPbPb 40 AGeV 0-5% central collisions (Rapp et al.)Measure the evolution of Teff vs mass vs beam energy

Phys. Rev. Lett. 91 (2003) 042301Higher baryon density at 40 than at 158 AGeVEnhancement factor:5.91.5(stat.)1.2(syst.)

(published 1.8 (syst. cocktail) removed due to the new NA60 results on the and FFs)Larger enhancement in support of the decisive role of baryon interactions Measuring the rho regionLarge enhancement: might not be just coincidental with expectation of emergence of CPOnly one exisiting measurement at 40 AGeV with very low statistics

Muon spectrometerToroid field (R=160 cm)beam5 m9Compress the spectrometer reducing the absorber and enlarge transverse dimensionsdimuons@160 GeV (NA60) rapidity coverage 2.9