Christine Nattrass University of Tennessee at Knoxville Calculations done on the Titan supercomputer by the CJet collaboration

Christine Nattrass (UTK), Rutgers, March 23, Phase diagram of nuclear matter Quark Gluon Plasma Core of neutron stars? Quark Gluon Plasma – a liquid of quarks and gluons created at temperatures above ~170 MeV (2·10 12 K) – over a million times hotter than the core of the sun

Christine Nattrass (UTK), Rutgers, March 23, How to make a Quark Gluon Plasma

Christine Nattrass (UTK), Rutgers, March 23, The phase transition in the laboratory

Christine Nattrass (UTK), Rutgers, March 23, STAR PHENIX PHOBOS BRAHMS Relativistic Heavy Ion Collider ALICE CMS ATLAS LHCf LHCb Large Hadron Collider Upton, NY 1.2km diameter p+p, d+Au, Cu+Cu, Au+Au, U+U √s NN = GeV Geneva, Switzerland 8.6km diameter p+p, p+Pb, Pb+Pb √s NN = 2.76 GeV, 5.5 TeV RHIC Quark Gluon Plasma Core of neutron stars? RHIC LHC

Christine Nattrass (UTK), Rutgers, March 23, STAR PHENIX ALICE CMS ATLAS

7 p+p collisions 3D image of each collision

Christine Nattrass (UTK), Rutgers, March 23, Pb+Pb collisions 5

Christine Nattrass (UTK), Rutgers, March 23, Measurements of transverse energy Fluid of quarks and gluons Energy density (Bjorken)

Christine Nattrass (UTK), Rutgers, March 23, Where is energy distributed in an event?

Christine Nattrass (UTK), Rutgers, March 23, Calculations from spectra The distribution of energy is surprisingly centrality independent.

Christine Nattrass (UTK), Rutgers, March 23, Where is the energy? Scale: diameter in inches = √fraction * 5 π0π0 π+π+ π-π- K+K+ K-K- K0K0 S K0K0 L p pp n nn Λ ΛΛ

Christine Nattrass (UTK), Rutgers, March 23, Where is the energy? π0π0 Scale: diameter in inches = √fraction * 5 π+π+ π-π- K+K+ K-K- K0K0 S K0K0 L p pp n nn Λ ΛΛ 57% charged 43% neutral Not 33% Not 67%

Christine Nattrass (UTK), Rutgers, March 23, How does it hit your detector? π0π0 Scale: diameter in inches = √fraction * 5 π+π+ π-π- K+K+ K-K- K0K0 S K0K0 L p pp n nn ΛΛ γγ π+π+ π-π- π0π0 π0π0 ~31% π0π0 π0π0 γ γ γγ Λ ~69% ~64% n π0π0 n γ γ ~36% p π-π- ~64% n π0π0 n γ γ ~36% pp π+π+

Christine Nattrass (UTK), Rutgers, March 23, How does it hit your detector? Scale: diameter in inches = √fraction * 5 π+π+ π-π- K+K+ K-K- K0K0 L p pp n nn γγ π0π0π0π0 π+π+ π-π- K0K0K0K0 S π0π0 π0π0 γ γ γγ K0K0K0K0 S n γ γ n γ γ p π-π-Λ Λ pp π+π+ ΛΛΛΛ ΛΛΛΛ

Christine Nattrass (UTK), Rutgers, March 23, How does it hit your detector? Scale: diameter in inches = √fraction * 5 π+π+ π-π- K+K+ K-K- K0K0 L p pp n nn γ γ π0π0π0π0 π+π+ π-π- K0K0K0K0 S π0π0 π0π0 γ γ γγ K0K0K0K0 S p π-π-Λ n γ γ Λ pp π+π+ ΛΛΛΛ n γ γ ΛΛΛΛ 65% charged 35% neutral 11% in neutral hadrons 7% in secondaries

Christine Nattrass (UTK), Rutgers, March 23, How does it hit your detector? Scale: diameter in inches = √fraction * 5 π+π+ π-π- K+K+ K-K- K0K0 L p pp n nn π+π+ π-π- K0K0K0K0 S n n Λ ΛΛΛΛ p π-π- Λ pp π+π+ ΛΛΛΛ γγ π0π0π0π0 π0π0 π0π0 γ γ γγ K0K0K0K0 S 24% as a γ γ γ ΛΛΛΛ γ γ Λ 11% as a neutral hadron 58% in primary hadrons 7% in secondary hadrons

Christine Nattrass (UTK), Rutgers, March 23, How does it hit your detector? Tracking detectors Scale: diameter in inches = √fraction * 5 π+π+ π-π- K+K+ K-K- K0K0 L p pp n nn γγ π0π0π0π0 π+π+ π-π- K0K0K0K0 S π0π0 π0π0 γ γ γγ K0K0K0K0 S n γ γ n γ γ Λ ΛΛΛΛ p π-π-Λ pp π+π+ ΛΛΛΛ 35% No signal 7% Secondaries 58% Primaries

Christine Nattrass (UTK), Rutgers, March 23, How does it hit your detector? Electromagnetic calorimeters Scale: diameter in inches = √fraction * 5 π+π+ π-π- K+K+ K-K- K0K0 L p pp n nn π+π+ π-π- K0K0K0K0 S n n Λ ΛΛΛΛ p π-π-Λ pp π+π+ ΛΛΛΛ Deposit about 1/3 of energy γ γ π0π0π0π0 π0π0 π0π0 γ γ γγ K0K0K0K0 S Deposit 100% of energy γ γ ΛΛΛΛ γ γ Λ 35% of energy in event 65% of energy in event

Christine Nattrass (UTK), Rutgers, March 23, Methods for measuring E T CMS: Tracking + electromagnetic calorimeter + hadronic calorimeter PHENIX: Electromagnetic calorimeter STAR: Tracking + Electromagnetic calorimeter ALICE: Tracking* *Other methods tried – focusing on this one here

Christine Nattrass (UTK), Rutgers, March 23, CMS Scale: diameter in inches = √fraction * 5 γγ π0π0π0π0 π0π0 π0π0 γ γ γγ K0K0K0K0 S 24% as a γ γ γ ΛΛΛΛ γ γ Λ K0K0 L n nn n n Λ ΛΛΛΛ 11% as a neutral hadron π+π+ π-π- K+K+ K-K- p pp π+π+ π-π- K0K0K0K0 S p π-π- Λ pp π+π+ ΛΛΛΛ 58% in primary hadrons 7% in secondary hadrons Measure in electromagnetic calorimeter Measure in tracking detectors and hadronic calorimeter Measure in hadronic calorimeter

Christine Nattrass (UTK), Rutgers, March 23, CMS Phys. Rev. Lett. 109, (2012) ~ 700 MeV/c Phys. Lett. B 727 (2013) Tracks: p T >900 MeV/c Clusters: limited by B → ~62% of energy measured

Christine Nattrass (UTK), Rutgers, March 23, PHENIX Scale: diameter in inches = √fraction * 5 π+π+ π-π- K+K+ K-K- K0K0 L p pp n nn π+π+ π-π- K0K0K0K0 S n n Λ ΛΛΛΛ p π-π-Λ pp π+π+ ΛΛΛΛ Deposit about 1/3 of energy γγ π0π0π0π0 π0π0 π0π0 γ γ γγ K0K0K0K0 S Deposit 100% of energy γ γ ΛΛΛΛ γ γ Λ 35% of energy in event 65% of energy in event → Measure ~57% of energy Uses electromagnetic calorimeter

Christine Nattrass (UTK), Rutgers, March 23, STAR Scale: diameter in inches = √fraction * 5 γ γ π0π0π0π0 π0π0 π0π0 γ γ γγ K0K0K0K0 S 24% as a γ γ γ ΛΛΛΛ γ γ Λ K0K0 L n nn n n Λ ΛΛΛΛ 11% as a neutral hadron π+π+ π-π- K+K+ K-K- p pp 58% in primary hadrons π+π+ π-π- K0K0K0K0 S p π-π- Λ pp π+π+ ΛΛΛΛ 7% in secondary hadrons Measure in electromagnetic calorimeter Measure in tracking detector Backgrounds Background

Christine Nattrass (UTK), Rutgers, March 23, ALICE Scale: diameter in inches = √fraction * 5 π+π+ π-π- K0K0K0K0 S p π-π- Λ pp π+π+ ΛΛΛΛ γγ π0π0π0π0 π0π0 π0π0 γ γ γγ K0K0K0K0 S 24% as a γ γ γ ΛΛΛΛ γ γ Λ K0K0 L n nn n n Λ ΛΛΛΛ 11% as a neutral hadron π+π+ π-π- K+K+ K-K- p pp 58% in primary hadrons 7% in secondary hadrons Measure in tracking detector Cut out using tight DCA cut Don't measure Measure ~56%

Christine Nattrass (UTK), Rutgers, March 23, ALICE 2% 3%40% 3% But known well! 45% What we measure directly Corrections

Christine Nattrass (UTK), Rutgers, March 23, ALICE: f total π0π0 Scale: diameter in inches = √fraction * 5 π+π+ π-π- K+K+ K-K- K0K0 S K0K0 L p pp n nn Λ ΛΛ π-π- π+π+ K+K+ K-K- p pp = ± 0.009

Christine Nattrass (UTK), Rutgers, March 23, Measuring energy with tracking detectors f total is robust Other corrections are either small or known well

Christine Nattrass (UTK), Rutgers, March 23, ET and Bjorken Energy Density D. Silvermyr, ORNL 29 Smooth scaling throughout RHIC energy range Collision energy

Christine Nattrass (UTK), Rutgers, March 23, √ s dependence: Nch & ET 30 dNch/d  /(0.5*Npart) ~ x RHIC 1.9 x pp (NSD) at 2.36 TeV growth with √s faster in AA than pp dET/d  /(0.5*Npart) ~ 9 in 0-5% Also increase of Npart (353 → 383) → 2.7 x RHIC for dET/d  (consistent with ~20% increase of, and expectations from spectra) Grows with power of CM energy faster than simple logarithmic scaling extrapolated from lower energy Plot: arXiv:

Christine Nattrass (UTK), Rutgers, March 23, Transverse Energy E T had from charged hadrons directly measured by the tracking detectors ftotal from MC to convert into total ET From RHIC to LHC ~2.5 increase in dET/d  / (0.5*Npart) Energy density (Bjorken)  ~ 15 GeV/(fm2c) RHIC:  =5.4±0.6 GeV/(fm2c) Centrality dependence similar to RHIC (PHENIX) PRC71: (2005) PRC70: (2004) (GeV)

Christine Nattrass (UTK), Rutgers, March 23, dET/d  Also for transverse energy: Approx. same centrality dependence at 7.7 GeV as at 2.76 TeV! Collision energy

Christine Nattrass (UTK), Rutgers, March 23, dNch/d  N.B.: Approx. same centrality dependence at 7.7 GeV as at 2.76 TeV! [note: no RHIC average here, just PHENIX..]

Christine Nattrass (UTK), Rutgers, March 23, ET/Nch Consistent behavior for ET and Nch - Both increase with energy Both show steady rise from peripheral to central ET/Nch ~ independent of centrality ET/Nch increases with energy PRC71:034908,2005 PRC70:054907,2004

Christine Nattrass (UTK), Rutgers, March 23, Conclusions Energy distribution in an event:  NOT 1/3 neutral!...but hits your detector as ~1/3 neutral Measurements of E T : tracking only measurements highly accurate! Several energy-independent trends

Christine Nattrass (UTK), Rutgers, March 23, The End

Christine Nattrass (UTK), Rutgers, March 23, Comparison of colliders RHICLHC √s NN (GeV) , 5500center of mass energy dN ch /dη~1200~1600number of particles T/T c temperature ε (GeV/fm 3 )5~15energy density τ QGP (fm/c)2-4>10lifetime of QGP RHIC and LHC: Cover 2 –3 decades of energy (√s NN = 9 GeV –5.5 TeV) To discover the properties of hot nuclear matter at T ~ 150 –600 MeV

Christine Nattrass (UTK), Rutgers, March 23, Hybrid method E t had π ∓,k ∓,p` p A. Well- measured by TPC B. Not well measured but included in def. n,K 0 L,`n C. Not included in def. but occurs as a background e∓e∓ K 0 S, Λ ` Λ D. Included in def, but will exclude with DCA and correct for missing energy E t em π 0,e ∓, γ, η E. Well- measured by EMCal Not included in def. but occurs as a background n,K0L,`n π ∓,k ∓,p` p Not included in def. but occurs as a background n,K0L,`n π ∓,k ∓,p` p F. Not included in def. but occurs as a background π ∓,k ∓,p` p n,K 0 L,`n Stuff the tracking detectors measure well Stuff the EMCal measures well

Christine Nattrass (UTK), Rutgers, March 23, Calculation from spectra Use spectra data and use Blast wave fits to extrapolate to higher and lower p T Three assumptions E T n =E T p E T `n =E T `p K 0 L =K 0 S Then, neglecting pseudorapidity dependence and assuming that the correction is the same for 900 GeV, 2.76 TeV, and 7 TeV: Everything else is negligible

Christine Nattrass (UTK), Rutgers, March 23, What does the EMCal measure? Note that this gets the fraction from kaons wrong. The fraction from kaons is actually about 10% of what we measure. Signal is actually ~30%.

Christine Nattrass (UTK), Rutgers, March 23, Kaon deposits There are several kaon decays into pi0's and pi0's decay mostly into photons These will (mostly) not be matched to tracks Simulations are unreliable because of how far off simulations are for strange particles

Christine Nattrass (UTK), Rutgers, March 23, Kaons – measured vs simulation

Christine Nattrass (UTK), Rutgers, March 23, E T em Geometric acceptance, not including dead channels efficiency x acceptance within geometric acceptance of detector ~1% Correction for (anti)neutron deposits in calorimeter ~1.5-5% Correction for deposits by particles from secondary interactions <4 <5% Sum over clusters Correction for minimum energy threshold ~6% Correction for nonlinearity of detector response ~0.5% All energy deposited by K 0 S, K 0 L, K ±, including decays like K 0 S →π 0 π 0 →γγγγ <3% Correction for other charged hadron deposits in calorimeter ~10-20% Data driven Input from data Contributions to final E T em systematic error

Christine Nattrass (UTK), Rutgers, March 23, E T had Correction for the geometric acceptance – 1, with acceptance due to sector boundaries, etc. rolled into the track efficiency Correction for the low p T cut off in the acceptance Correction for neutral hadrons included in the definition but not measured well: K 0 S, Λ, ` Λ, K 0 L, n,`n Not trying to measure K 0 S, Λ, ` Λ in TPC – apply DCA cut to eliminate, correct for missing energy Correction for background not included in definition (e ∓ ) or not measured easily event-by-event (K 0 S, Λ, ` Λ ) Correction for π, K, p not identified Correction for tracking efficiency Definition of energy to mimic the behavior of a calorimeter

Christine Nattrass (UTK), Rutgers, March 23, From RHIC to LHC PHOBOS, Nucl. Phys. A747, 28 (2003) Pre-RHIC theoretical predictions: Seems straightforward to extrapolate to LHC, right..?

Christine Nattrass (UTK), Rutgers, March 23, First LHC HI Results: Charged Particle Multiplicity 5% most central events: dNch/d  = 1584 ±4(stat)±76(sys) Predictions more spread around result (on high side of expectations) than at start of RHIC Excellent agreement also between LHC experiments! Pb-Pb(√sNN= 2.76 TeV) → 1.9 x p-p(√sNN= 2.36 TeV) → nuclear amplification! → 2.1 x RHIC (Au-Au√sNN= 0.2 TeV) Plot: arXiv:

Christine Nattrass (UTK), Rutgers, March 23, Summary The bulk properties of the system show a smooth transition throughout RHIC energy range and on to LHC energies LHC multiplicity (many predictions) and transverse energy (fewer comparisons) values higher than many predictions based on RHIC data Centrality dependence very similar from lowest RHIC to highest LHC √s (PHENIX & ALICE): “just” rapidity distribution narrowing/geometry? LHC Energy density > 15 GeV/fm3 → ~>3x RHIC Thanks to A. Milov, A. Toia, M. Floris, C. Nattrass, J. Mitchell for input/slides..

Christine Nattrass (UTK), Rutgers, March 23, Multiplicity vs centrality From RHIC to LHC dNch/d  ~1600 for 0- 5%: ~2.1 increase Similar centrality dependence at 0.2 and 2.76 TeV for Npart>100 (RHIC average) Good “matching” to the pp point Measurement based on tracklet reconstruction in SPD |  |<0.5 Interpolations between 2.36 and 7 TeV pp PRL106, (2011) PRC71, (2005) PRC83, (2011) LHC scale RHIC scale

Christine Nattrass (UTK), Rutgers, March 23, Mid-rapidity dNch/d  vs centrality Multiplicity scaling with centrality: Stronger than Npart Different possible scalings (2 component, power laws) reproduce data Glauber fits not sensitive to choice of parameterization Scaling similar to RHIC: Contribution of hard processes (Ncoll scaling) the same as at lower energies..? Just geometry? Plot: arXiv:

Christine Nattrass (UTK), Rutgers, March 23, Observables at high rapidity dNch/d  at forward rapidity SPD: mid rapidity VZERO, FMD Phenomena at high rapidity properties of initial state (e.g. Color Glass condensate, gluon density,...) energy and baryon stopping similar trend for measured  bins Note: suppressed y-scale..

Christine Nattrass (UTK), Rutgers, March 23, Extended longitudinal scaling Yields at high rapidity are energy- independent, when viewed in rest- frame of one of colliding nuclei longitudinal scaling could be present also for Pb+Pb at 2.76 TeV Works also for dN/d  because y≈  + ln (pT/mT) ≈  BRAHMS data scaled by Npart(ALICE)/Npart(BRAHMS)  -ybeam > -3: extrapolations (double-Gaussian, linear) BRAHMS PRL 88:202301,2001

Christine Nattrass (UTK), Rutgers, March 23,  Centrality shape scales with incident beam energy  Steady rise from peripheral to central a la Nch PHENIX PRC 71, (2005) ET Measurements STAR:TPC + calorimetry PHENIX: calorimetry only STAR (PRC 70, (2004))

Where do the particles go? D. Silvermyr, ORNL 53 22% y = 0.5ln(E+pz)/(E-pz) ybeam = ln(√s/mp) sinh(η) = mT/pT sinh(y) Only ~22% of all emitted particles have pT > pL Measurements at mid-rapidity carry information about the most dense region in the collision => Let’s focus on this region next.. PHOBOS