beam energy and system size scan at the CERN SPS M. Gazdzicki, - PowerPoint PPT Presentation

NA49/NA61: results and plans on beam energy and system size scan at the CERN SPS M. Gazdzicki, Frankfurt, Kielce for the NA49 and NA61 Collaborations Onset of deconfinement: - NA49 evidence - NA61 systematic study Critical point: - NA49 pilot results - NA61 systematic search 1

Onset of deconfinement: AGS SPS RHIC NA49 evidence in single particle yields and spectra Kink hadron production properties Onset of Deconfinement: early stage hits transition line, observed signals: kink, horn, step T Predictions: Results: APP B30 2705 (99), PR C77 024903 (08) energy Horn Step µ B 2 collision energy

Evidence: single particle yields the kink the horn pion yield per participant ratio of strange particle to pion yield APP B30 2705 (99) APP B30 2705 (99) - > < π > = ⋅ < π + > + < π 1.5 ( ) central PbPb/AuAu central PbPb/AuAu - > < π > = ⋅ < π + > + < π 1.5 ( ) ≈ 1/4 s NN - π yield related to entropy production - E s related to strangeness/entropy ratio - steeper increase in A+A suggests - plateau consistent with prediction for 3-fold increase of initial d.o.f deconfinement 3

Evidence: single particle spectra the dale the step shape of transverse mass spectra sound velocity from rapidity spectra nucl-th/0611001 PL B567 175 SPheRIO central PbPb/AuAu softening of EoS due to mixed phase influence transverse (left) and longitudinal (right) expansion 4

Verification of the NA49 evidence by STAR in progress 30 A GeV p T (GeV/c) STAR 1 Plots to be updated NA49 0 2 -2 0 y NA49 pion and kaon spectra near mid-rapidty (in common acceptance) are published, final STAR spectra expected to be available soon. Preliminary STAR results are consistent with the NA49 ones. 5

NA49 search for the onset signal in fluctuations Multiplicity fluctuations in central (1%) Pb+Pb collisions (PR C78 034914) Energy dependence of scaled variance Example distribution at 158 A GeV Data narrower 158 80 40 30 20 than Poisson Onset of deconfinement: Collisions with a fixed number of an increase at about 80 A GeV participants have to be selected. This is impossible in by about 0.01 ( PL B585 115 ). collider experiments. Predicted effect smaller than Verification by STAR impossible. the systematic errors 6

NA49 search for the onset signal in fluctuations Energy dependence of chemical fluctuations in central (3.5%) Pb+Pb collisions (arXiv:1101.3250) (Tim Schuster, Tuesday 18:40) 30 A GeV p T (GeV/c) STAR 1 NA49 20 30 40 80 158 0 2 -2 0 y Dynamical K/p fluctuations change Comparison between NA49 sign at the onset energy. This is not and STAR requires new described by hadronic models. results from both experiments Is this observation related to the in the common acceptance. tooth prediction ( PL B585 237 ) for 7 the onset of deconfinement?

NA61 systematic study of the onset of deconfinement ? 10 20 30 40 80 158 energy ( A GeV) Search for the onset of the signals in collisions of light nuclei 8

Progress and plans in data taking for CP&OD (central events only) Pb+Pb NA49 (1996-2002) Au+Au STAR (2008-11) NA61 ion program Xe+La 2015 Ar+Ca 2014 T T Be+Be 2010/11/12 p+p P p+p 2009/10/11 p+Pb 158 2012/14 13 20 30 40 80 158 T -test of secondary ion beams energy ( A GeV) P -pilot data taken 9

NA61 preliminary results on p+p and p+C collisions Pion spectra at 31 GeV/c (arXiv:1101.3250 and Antoni Aduszkiewicz, poster ....) 2007 2009 To be replaced by rapidity spectra from Antoni/Tomek 2009 2007 2009 10

Critical point: NA49 pilot results Critical Point: freeze-out close to critical point, and system large enough, expected signal: a hill in fluctuations T energy Pb+Pb A Be+Be 13 µ B Search for the critical point makes sense only at energies larger than 11 the onset one (30 A GeV)

Critical point: NA49 pilot results system size at 158 A GeV energy for central Pb+Pb First hint of the PR C78:034914 fluctuation hill? 12 PR D60:114028

Critical point: NA49 pilot results 3 rd moment of p T fluctuations Φ pT (3) has strongly intensive property like Φ pT NA49 preliminary system size at 158 A GeV Higher moments are expected to be more sensitive to fluctuations, but no theoretical predictions yet. Data systematic errors are large. 13

Critical point: NA49 pilot result Intermittency of pion pairs at 158 A GeV ( PR C81:064907 ) Combinatorial background too large Indications for the intermittency signal for central Si+Si collisions at 158 A GeV. 14

Critical point: NA61 systematic search NA61 ion program Xe+La 2015 Ar+Ca 2014 T T Be+Be 2010/11/12 p+p P 2009/10/11 p+Pb 2012/14 13 20 30 40 80 158 T -test of secondary ion beams energy ( A GeV) P -pilot data taken 15

Critical point: NA61 systematic search Advances in analysis methods Two families of strongly intensive quantities were identified (quantities which are independent of volume and volume fluctuations with the grand canonical ensemble and wounded nucleon model, arXiv:1101.4865 ) Thei use should significantly reduce uncertainties due to fluctuations in collision geometry. Use of the identity method to study chemical fluctuations ( arXiv:1103.2887 ) should significantly reduce uncertainties introduced by the currently used methods (NA49: event-by-event maximum likelihood fit, STAR: particle counting in dE/dx-tof windows). In particular important for low multiplicity events studied by NA61 16

Critical point: NA61 systematic search Experimental techniques Beams: Detector: primary Ar and Xe Large acceptance: ≈50% secondary p and Be High momentum resolution: 2 ≈ 10 − 4 − 1   p / p  GeV / c  at full magnetic field High detector efficiency: > 95% Event rate: 70 events/sec High spectator resolution: proj ≈ 1  N spec 17

Summary NA49: Onset of deconfinement: - strong evidence in single particle yields and spectra, - new: possible signal in kaon to proton fluctuations, - comparison between NA49 and STAR in progress NA49: Critical point: - pilot results on system size scan at 158 A GeV show enhanced fluctuations in Si+Si collisions, they are consistent with expectations for the critical point. NA61: Onset of deconfinement and critical point: - scan in beam energy and system size started with p+p interactions at six momenta (13-158 GeV/c), - first results are being released, - energy scan with Be beam will start this year 18

Additional slides 19

Detector and data taking Large acceptance: ≈50% High momentum resolution: 2 ≈ 10 − 4 − 1   p / p  GeV / c  at full magnetic field High detector efficiency: > 95% Event rate: 20 70 events/sec

Particle identification Good particle identification:  TOF ≈ 60 − 120 ps ,  dE / dx /〈 dE / dx 〉≈ 0.04 ,  m inv ≈ 5 MeV 21

Ion beams for NA61 Primary Ar, Xe and Pb beams COMPASS a rthAre No SPS T1 8 * LHC ECR ion source neut rinos T1 CNGS 2 E D TT1 n -TOF L O A 0 D S * Ea s tAre a I * pbar PSB PS E1 TT2 E0 Gra nS a s s o( I) CTF3 730 km LINAC2 LINAC3 E2 LEIR p P bio n s LINAC 3 22

Secondary Berillium beam: basic idea Pb primary fragmentation Pb fragments fragment Pb beam target separator from the SPS The pilot NA49 studies 23

Secondary Berillium beam: fragment separator  The beam line is a double spectrometer with 0.04% resolution that helps to separate the ion fragments corresponding to a selected magnetic rigidity : B ρ  Target length optimized to fragment production, degrader with variable length – optimization to be determined from the tests 500 m 24

Secondary hadron beams NA61 beam and trigger counters secondary hadron beam C1 and C2 - hadron identification (Cerenkov), S1, S2, V0, V1, BPD1/2/3 – determination of proton trajectory, S4 – selection of h+target interactions all beam p triggered particles protons π selection of beam protons at 31 GeV/c using Cerenkov detectors p π 25

Experimental landscape of complementary programs of nucleus-nucleus collisions around the SPS energies Facility: SPS RHIC NICA SIS-100 (SIS-300) Exp.: NA61 STAR MPD CBM PHENIX Start: 2010 2010 2015 2017 (2019) Pb Energy: 4.9-17.3 7.7-50 ≤11 ≤5 (<8.5) (GeV/(N+N)) Event rate: 70 Hz 3-30 Hz ≤10 kHz ≤10 MHz (at 8 GeV) Physics: CP&OD CP&OD OD&HDM HDM (OD) under consideration: U70 in IHEP Protvino CP – critical point OD – onset of deconfinement, mixed phase, 1 st order PT 26 HDM – hadrons in dense matter