Neptune discovery in physics class: activities and simulations
Heavy Ion Physics at NICA Simulations G.Musulmanbekov, V. Toneev and the Physics Group on NICA
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Transcript of Heavy Ion Physics at NICA Simulations G.Musulmanbekov, V. Toneev and the Physics Group on NICA
Heavy Ion Physics at NICASimulations
G.Musulmanbekov, V. Toneevand the Physics Group on NICA
Search for signals of Phase Transition in Au + Au collisions at √sNN = 3 – 9 GeV
Motivation
• The main goal of the NICA experiment is to study the behaviour of nuclear matter in vicinity of the QCD critical endpoint.
• To extract information on the equation-of-state of baryonic matter at high densities.
• Search for signals of Phase Transition in Au + Au collisions at √sNN = 3 – 9 GeV
Search for signals of Phase Transition in Au + Au collisions at √sNN = 3 – 9 GeV
Signatures of Possibile Phase Transition :
o Strange particle enhancement
o Hard spectrum of strange mesons
o Charmonium suppression
o Dielectron mass spectrum enhancement at the range 0.2 – 0.6 GeV/c
Search for signals of Phase Transition in Au + Au collisions at √sNN = 3 – 9 GeV
Observables :
• Global characteristics of identified hadrons, including strange baryons
• Strange to non-strange particles ratio
• Transverse momentum spectra
• Fluctuations in multiplicity and transverse momenta
• Directed and elliptic flows
• Particle correlations (femtoscopy, HBT correlations)
• Dilepton spectra
Search for signals of Phase Transition in Au + Au collisions at √sNN = 3 – 9 GeV
Simulation Tools :
• UrQMD 1.3, UrQMD 2.2o 104 central events at 3, 3.8, 5, 7, 9 GeVo 105 min bias events at 3, 3.8, 5, 7, 9 GeV
• FastMCo 104 central events at 3, 5, 7, 9 GeV
• PLUTO
o 106 central events at 3, 5, 7, 9 GeV
Mean multiplicities in Au-Au collisions Simulated by UrQMD min.bias events
Mean multiplicities in Au-Au collisions Simulated by UrQMD central collisions (b ≤ 3 fm)
Mean multiplicities in Au-Au collisions Simulated by UrQMD central collisions (b ≤ 3 fm)
Mean multiplicities in Au-Au collisions Simulated by UrQMD central collisions (b ≤ 3 fm)
Simulated charged multiplicity distributionsin central collisions (b < 3fm)
Simulated charged pseudorapidity distributions in central collisions (b < 3fm)
Simulated charged pseudorapidity distributions in central collisions (b < 3fm)
MPD-2 < η < 2
Simulated charged pseudorapidity distributions in central collisions (b < 3fm)
MPD-1 < η < 1
Strange Baryons Yield
Table: Marked hyperons are accessible through their decays into charged hadrons
Accessible Hyperons
Mass(GeV/c2) Lifetime cτ (cm) Multiplicity Decay channel
BR(%) Registration efficiency (%)|p| > 0.1 GeV/c
-1 < y < 1
ΛΞ-
Ω-
1.1161.3211.672
7.894.912.46
39.81.210.03
p + π-
Λ + π-
Λ + K-
63.999.967.8
1685
Accessible Hyperons
Λ → pπ- Ξ- → Λπ- → pπ- π- Ω- → ΛK- → pK- π-
Strange to non-Strange ratios in central collisions
“Horn” Effect
<π- >/<π+>Au+Au/Pb+Pb, central
<K+ >/<π+>Au+Au/Pb+Pb, central
Strange to non-Strange ratios in central collisions
“Horn” Effect
Strange to nonStrange ratios in central collisions
Strange to nonStrange ratios in central collisions
Strange to nonStrange ratios in central collisions
Transverse Mass Spectra of Mesonsin central collisions
T
m
dm
dN
mT
TT
exp1
T – inverse slope
Transverse Mass Spectra of Mesonsin central collisions
Transverse Mass Spectra of Mesonsin central collisions
Scaled multiplicity variances
i
ii
N
NN22
ω (h+)
ω (h-)
ω (hch)
Scaled multiplicity variancesNA49 results
NA49 result: Measured scaled variances are close to the Poisson one – close to 1!No sign of increased fluctuations as expected for a freezeout near the critical point of strongly interacting matter was observed.
Transverse momentum fluctuations
To exclude trivial fluctuations from consideration the following variable is used:
For the system of independently emitted particles (no inter-particle correlations) Фpt
goes to zero.
Directed flow v1 & elliptic flow v2
x
zNon-central Au+Au collisions:
Interactions between constituents leads to a pressure gradients => spartial asymmetry is converted in asymmetry in momentum space
=> collective flows
22
22
yx
yx2
T
x1
21TTTT
pp
ppv
p
pv
...)cos(22v)cos(2v12π
1
dpdyp
dN
ddpdyp
dN
- directed flow
- elliptic flowV2>0 indicates in-plane emission of
particlesV2<0 corresponds to out-of-plane
emission (squeeze-out perpendicular to the reaction plane)
Direct flow Au + Au collisions at √sNN = 7GeV, b = 5 – 9 fm
Direct flow slopeCollision Energy Dependence
Au + Au, b = 5 – 9 fm
Elliptic flow Au + Au collisions at √sNN = 7GeV, b = 5 fm
Elliptic flow Collision Energy Dependence
Au+Au/Pb+Pb, b = 5 – 9 fm
Sergey Panitkin
qout
qside
qlong
HBT interferometry
Rsi
de
R long
Rout
x1
x2
12 ppq
p1
p2
q
12 pp2
1k
Two-particle interferometry: p-space separation space-time separation
HBT: Quantum interference between identical particles
pairsevent mixed
pairsevent real
)(P)(P
),(P),(
21
2121
pp
ppppC
2long
2long
2side
2side
2out
2out)(1),(
RqRqRqekkqC
q (GeV/c)q (GeV/c)
C (
q)C
(q)
11
22R
1~
– Final-state effects (Coulomb, strong) also can cause correlations, need to be accounted for
Gaussian model (3-d):
HBT interferometry
)qRqRqRexp(1)q,q,q(C 2S
2S
2O
2O
2L
2LLS0
HBT interferometry
HBT interferometry
Dilepton Spectra
Dilepton Spectra
Dilepton Spectra
Dilepton Spectra
Dilepton Spectra
Conclusions
New simulation codes which take into accountphase transitions of deconfinement and/or chiral symmetry restoration are needed.
Thank you!