charged particle multiplicity studies with phobos birger back argonne national laboratory for the...
TRANSCRIPT
![Page 1: Charged particle multiplicity studies with PHOBOS Birger Back Argonne National Laboratory for the PHOBOS Collaboration](https://reader030.vdocuments.mx/reader030/viewer/2022032723/56649f575503460f94c7c340/html5/thumbnails/1.jpg)
Charged particle multiplicity studies with PHOBOS
Birger Back
Argonne National Laboratory
for the
PHOBOS Collaboration
![Page 2: Charged particle multiplicity studies with PHOBOS Birger Back Argonne National Laboratory for the PHOBOS Collaboration](https://reader030.vdocuments.mx/reader030/viewer/2022032723/56649f575503460f94c7c340/html5/thumbnails/2.jpg)
2
PHOBOS Collaboration
Burak Alver, Birger Back, Mark Baker, Maarten Ballintijn, Donald Barton, Russell Betts, Richard
Bindel,
Wit Busza (Spokesperson), Vasundhara Chetluru, Edmundo García, Tomasz Gburek, Joshua
Hamblen, Conor Henderson, David Hofman, Richard Hollis, Roman Hołyński, Burt Holzman, Aneta
Iordanova, Chia Ming Kuo, Wei Li, Willis Lin, Constantin Loizides, Steven Manly, Alice Mignerey,
Gerrit van Nieuwenhuizen, Rachid Nouicer, Andrzej Olszewski, Robert Pak, Corey Reed, Christof
Roland, Gunther Roland, Joe Sagerer, Peter Steinberg, George Stephans, Andrei Sukhanov,
Marguerite Belt Tonjes, Adam Trzupek, Sergei Vaurynovich, Robin Verdier, Gábor Veres, Peter
Walters, Edward Wenger, Frank Wolfs, Barbara Wosiek, Krzysztof Woźniak, Bolek Wysłouch
ARGONNE NATIONAL LABORATORY BROOKHAVEN NATIONAL LABORATORYINSTITUTE OF NUCLEAR PHYSICS PAN, KRAKOW MASSACHUSETTS INSTITUTE OF TECHNOLOGY
NATIONAL CENTRAL UNIVERSITY, TAIWAN UNIVERSITY OF ILLINOIS AT CHICAGOUNIVERSITY OF MARYLAND UNIVERSITY OF ROCHESTER
![Page 3: Charged particle multiplicity studies with PHOBOS Birger Back Argonne National Laboratory for the PHOBOS Collaboration](https://reader030.vdocuments.mx/reader030/viewer/2022032723/56649f575503460f94c7c340/html5/thumbnails/3.jpg)
3
PHOBOS experiment: June 2000 – June 2005
-5.4 < < 5.40.5o < < 179.5o
Main emphasis:
4 multiplicity and
low pT particles
![Page 4: Charged particle multiplicity studies with PHOBOS Birger Back Argonne National Laboratory for the PHOBOS Collaboration](https://reader030.vdocuments.mx/reader030/viewer/2022032723/56649f575503460f94c7c340/html5/thumbnails/4.jpg)
4
PHOBOS multiplicity measurements
System s1/2 (GeV)
Au+Au 200, 130, 62.4, 19.6
Cu+Cu 200, 62.4, 22.4
d+Au 200
p+p 200, 410
![Page 5: Charged particle multiplicity studies with PHOBOS Birger Back Argonne National Laboratory for the PHOBOS Collaboration](https://reader030.vdocuments.mx/reader030/viewer/2022032723/56649f575503460f94c7c340/html5/thumbnails/5.jpg)
5
dN/d basics
![Page 6: Charged particle multiplicity studies with PHOBOS Birger Back Argonne National Laboratory for the PHOBOS Collaboration](https://reader030.vdocuments.mx/reader030/viewer/2022032723/56649f575503460f94c7c340/html5/thumbnails/6.jpg)
6
What would an isotropic source look like?
Isotropic emission: 1/cosh2
Only 22% emittedwith pT > pL
Theseparticles carry information aboutthe densest regionformed in the collisions
![Page 7: Charged particle multiplicity studies with PHOBOS Birger Back Argonne National Laboratory for the PHOBOS Collaboration](https://reader030.vdocuments.mx/reader030/viewer/2022032723/56649f575503460f94c7c340/html5/thumbnails/7.jpg)
7
What happens to the original protons?
AGS
SPS
RHIC 62
RHIC 200
LHC 5500
(BRAHMS preliminary)
dN
/dy
I.Bearden (BRAHMS), QM2006
Net (original) protons move away from mid-rapidity region with increasing collision energy
Mid-rapidity region begins to look like a pure energy-density region reminiscent of the early universe
![Page 8: Charged particle multiplicity studies with PHOBOS Birger Back Argonne National Laboratory for the PHOBOS Collaboration](https://reader030.vdocuments.mx/reader030/viewer/2022032723/56649f575503460f94c7c340/html5/thumbnails/8.jpg)
8
dN/d @ =0
![Page 9: Charged particle multiplicity studies with PHOBOS Birger Back Argonne National Laboratory for the PHOBOS Collaboration](https://reader030.vdocuments.mx/reader030/viewer/2022032723/56649f575503460f94c7c340/html5/thumbnails/9.jpg)
9
Pre-RHIC theoretical predictions
PHOBOS, Nucl. Phys. A747, 28 (2005)
First RHIC
results
New dataPRC 74, 021901
(2006)
![Page 10: Charged particle multiplicity studies with PHOBOS Birger Back Argonne National Laboratory for the PHOBOS Collaboration](https://reader030.vdocuments.mx/reader030/viewer/2022032723/56649f575503460f94c7c340/html5/thumbnails/10.jpg)
10
Factorization of centrality and energy dependence
)N(g)s(fd
dNpart0
ch ||<1
Data: PHOBOS, PRL 97, 012301 (2006); PRC70, 021902(R) (2004); PRC65, 061901(R) (2002)
![Page 11: Charged particle multiplicity studies with PHOBOS Birger Back Argonne National Laboratory for the PHOBOS Collaboration](https://reader030.vdocuments.mx/reader030/viewer/2022032723/56649f575503460f94c7c340/html5/thumbnails/11.jpg)
11
Energy density
![Page 12: Charged particle multiplicity studies with PHOBOS Birger Back Argonne National Laboratory for the PHOBOS Collaboration](https://reader030.vdocuments.mx/reader030/viewer/2022032723/56649f575503460f94c7c340/html5/thumbnails/12.jpg)
12
Energy density estimates?
Absolute maximum:Total available energy:
Volume at instant of overlap:
Instantaneous energy density:Not equilibrated matter
Birger’s estimate:Isotropic energy:
Volume after 0 =1 fm/c:
Equilibrated energy density:
35,000GeV200/2350/2sNE NNparttot
3333 fm 14fm /100734
r34
V
/
33max0 GeV/fm 2,500GeV/fm 1435,000 /
GeV 1,2150.6/0.631275/fm NE chtisoch
isotot
30
2 fm 300249c2rV
33iso0 GeV/fm 4GeV/fm 3001,215 /
![Page 13: Charged particle multiplicity studies with PHOBOS Birger Back Argonne National Laboratory for the PHOBOS Collaboration](https://reader030.vdocuments.mx/reader030/viewer/2022032723/56649f575503460f94c7c340/html5/thumbnails/13.jpg)
13
Bjorken estimate of energy density
Phenix: ET measurement at 130 GeV
0 = 4.6 [GeV/fm3] PRL 87, 052301 (2001)
NA49: ET measurement at 17 GeV
0 = 3 [GeV/fm3] PRL 75, 3814 (1995)
Brahms
Conclusion: All reasonable estimates are substantially larger than thepredicted transition density of0 = 0.7-1.0 GeV/fm3
![Page 14: Charged particle multiplicity studies with PHOBOS Birger Back Argonne National Laboratory for the PHOBOS Collaboration](https://reader030.vdocuments.mx/reader030/viewer/2022032723/56649f575503460f94c7c340/html5/thumbnails/14.jpg)
14
CompletedN/d
distributions
![Page 15: Charged particle multiplicity studies with PHOBOS Birger Back Argonne National Laboratory for the PHOBOS Collaboration](https://reader030.vdocuments.mx/reader030/viewer/2022032723/56649f575503460f94c7c340/html5/thumbnails/15.jpg)
15
PHOBOS Au+Au Data
* PHOBOS PRL 91,52303 (2003)
PHOBOS, PRL 91, 052303 (2003); PRC 74, 021901 (2006)
![Page 16: Charged particle multiplicity studies with PHOBOS Birger Back Argonne National Laboratory for the PHOBOS Collaboration](https://reader030.vdocuments.mx/reader030/viewer/2022032723/56649f575503460f94c7c340/html5/thumbnails/16.jpg)
16
Cu+Cu data
![Page 17: Charged particle multiplicity studies with PHOBOS Birger Back Argonne National Laboratory for the PHOBOS Collaboration](https://reader030.vdocuments.mx/reader030/viewer/2022032723/56649f575503460f94c7c340/html5/thumbnails/17.jpg)
17
Centrality (%)
Npart
(total)
Npart
(Au)
Npart
(d)
0-20 15.5 13.5 2.0
20-40 10.8 8.9 1.9
40-60 7.2 5.4 1.7
60-80 4.2 2.9 1.4
80-100 2.7 1.6 1.1
d+Au centrality dependence
PHOBOS, Phys. Rev. C72, 031901(R) (2005)
d Au
Central: asymmetric
Peripheral: symmetric
Momentum conservation?
Peripheral
Central
>
~
![Page 18: Charged particle multiplicity studies with PHOBOS Birger Back Argonne National Laboratory for the PHOBOS Collaboration](https://reader030.vdocuments.mx/reader030/viewer/2022032723/56649f575503460f94c7c340/html5/thumbnails/18.jpg)
18
System size:Au+Au
vs.Cu+Cu
![Page 19: Charged particle multiplicity studies with PHOBOS Birger Back Argonne National Laboratory for the PHOBOS Collaboration](https://reader030.vdocuments.mx/reader030/viewer/2022032723/56649f575503460f94c7c340/html5/thumbnails/19.jpg)
19
Unscaled dN/d very similar for Au+Au and
Cu+Cu at same Npart
Scaling Laws
Cu+CuPreliminary
3-6%, Npart = 100
PHOBOS PHOBOS
62.4 GeV 200 GeV
Au+Au35-40%,Npart = 98
Cu+CuPreliminary
3-6%, Npart = 96Au+Au35-40%, Npart = 99
See poster by Richard Hollis
dN/d in Cu+Cu vs Au+Au for Npart ~ 100
![Page 20: Charged particle multiplicity studies with PHOBOS Birger Back Argonne National Laboratory for the PHOBOS Collaboration](https://reader030.vdocuments.mx/reader030/viewer/2022032723/56649f575503460f94c7c340/html5/thumbnails/20.jpg)
20
Unscaled dN/d very similar for Au+Au and Cu+Cu
at same Npart
Scaling Laws
Cu+CuPreliminary
15-25%, Npart = 61
PHOBOS PHOBOS
62.4 GeV 200 GeV
Au+Au45-50%,Npart = 62
Cu+CuPreliminary
15-25%, Npart = 60
Au+Au45-55%, Npart = 56
Also true for mid-central Cu+Cu vs peripheral Au+Au
dN/d in Cu+Cu vs Au+Au for Npart ~ 60
![Page 21: Charged particle multiplicity studies with PHOBOS Birger Back Argonne National Laboratory for the PHOBOS Collaboration](https://reader030.vdocuments.mx/reader030/viewer/2022032723/56649f575503460f94c7c340/html5/thumbnails/21.jpg)
21
Extended longitudinal scaling
![Page 22: Charged particle multiplicity studies with PHOBOS Birger Back Argonne National Laboratory for the PHOBOS Collaboration](https://reader030.vdocuments.mx/reader030/viewer/2022032723/56649f575503460f94c7c340/html5/thumbnails/22.jpg)
22
Extended longitudinal scaling – Au+Au
PHOBOS Phys. Rev. Lett. 91, 052303 (2003) / Nucl. Phys. A757, 28 (2005)
beamyydy
dN independent of energy
Works also for dN/d because:
)m/pln(y tt
![Page 23: Charged particle multiplicity studies with PHOBOS Birger Back Argonne National Laboratory for the PHOBOS Collaboration](https://reader030.vdocuments.mx/reader030/viewer/2022032723/56649f575503460f94c7c340/html5/thumbnails/23.jpg)
23
Scaling Laws
19.6 GeV 62.4 GeV 130 GeV 200 GeV
PHOBOS preliminary
preliminary preliminary preliminary preliminary
“Extended Longitudinal Scaling” of all longitudinal distributions
- ybeam
preliminary
PHOBOSAu+Au0-6%
Au+Au0-40%
Au+Au0-40%
200GeV130GeV62.4 GeV (prel)19.6 GeV
Extended longitudinal scaling – Au+Au
![Page 24: Charged particle multiplicity studies with PHOBOS Birger Back Argonne National Laboratory for the PHOBOS Collaboration](https://reader030.vdocuments.mx/reader030/viewer/2022032723/56649f575503460f94c7c340/html5/thumbnails/24.jpg)
24
Scaling Laws
Same for Cu+Cu
preliminarypreliminary
preliminary preliminaryPHOBOS
62.4 GeV 200 GeV
‘Extended Longitudinal Scaling’ also seen in Cu+CuPersists from p+p to Au+Au over large range in ’
preliminary
preliminary
PHOBOS
- ybeam
Cu+Cu0-6%
200GeV
62.4GeV
Cu+Cu0-40%
![Page 25: Charged particle multiplicity studies with PHOBOS Birger Back Argonne National Laboratory for the PHOBOS Collaboration](https://reader030.vdocuments.mx/reader030/viewer/2022032723/56649f575503460f94c7c340/html5/thumbnails/25.jpg)
25
Extended longitudinal scaling in p-A and d-A
PHOBOS, Phys. Rev. C72, 031901(R) (2005)
![Page 26: Charged particle multiplicity studies with PHOBOS Birger Back Argonne National Laboratory for the PHOBOS Collaboration](https://reader030.vdocuments.mx/reader030/viewer/2022032723/56649f575503460f94c7c340/html5/thumbnails/26.jpg)
26
Total charged particle multiplicity
![Page 27: Charged particle multiplicity studies with PHOBOS Birger Back Argonne National Laboratory for the PHOBOS Collaboration](https://reader030.vdocuments.mx/reader030/viewer/2022032723/56649f575503460f94c7c340/html5/thumbnails/27.jpg)
27
Total charged particle multiplicities in Au+Au
Nch Q Npart
Width x height = const
![Page 28: Charged particle multiplicity studies with PHOBOS Birger Back Argonne National Laboratory for the PHOBOS Collaboration](https://reader030.vdocuments.mx/reader030/viewer/2022032723/56649f575503460f94c7c340/html5/thumbnails/28.jpg)
28
Total multiplicity as a function of energyNch= dN/dx(2ybeam+0.3-dN/d/195)
height x width
width
hei
ght
PHOBOSPRL 91,52303 (2003)
![Page 29: Charged particle multiplicity studies with PHOBOS Birger Back Argonne National Laboratory for the PHOBOS Collaboration](https://reader030.vdocuments.mx/reader030/viewer/2022032723/56649f575503460f94c7c340/html5/thumbnails/29.jpg)
29
Energy dependence of Nch
0.31s0.77lndη
dNN
2
where
dηdN
1951
0.32ydη
dNN
2N2N
ch
part
chbeam
ch
partpart
ch
,
0-6% Central AuAu collisions
Npart=344
PHOBOS, PRL 91,52303 (2003)
![Page 30: Charged particle multiplicity studies with PHOBOS Birger Back Argonne National Laboratory for the PHOBOS Collaboration](https://reader030.vdocuments.mx/reader030/viewer/2022032723/56649f575503460f94c7c340/html5/thumbnails/30.jpg)
30
Universality – comparing AA to pp and e+e-
PHOBOS, PRC 74, 021902(R) (2006)
Shapes: Au+Au and e+e- “similar”Total Nch: Au+Au same as e+e-
p+p: leading hadron removes 50% of energy
![Page 31: Charged particle multiplicity studies with PHOBOS Birger Back Argonne National Laboratory for the PHOBOS Collaboration](https://reader030.vdocuments.mx/reader030/viewer/2022032723/56649f575503460f94c7c340/html5/thumbnails/31.jpg)
31
Evolution of Nch/Npp ratio vs Npart
Nch/(Npart/2) constant with centrality
d+Au also lower than Au+Au
d+Au data similar to low-energy p+A
NchdAu=0.5 Npart Nch
pp
(1 Deuteron = 2 protons)
d+Au: Centrality dependence of total Nch
PHOBOS, Phys. Rev. C72, 031901(R) (2005)
![Page 32: Charged particle multiplicity studies with PHOBOS Birger Back Argonne National Laboratory for the PHOBOS Collaboration](https://reader030.vdocuments.mx/reader030/viewer/2022032723/56649f575503460f94c7c340/html5/thumbnails/32.jpg)
32
Other new PHOBOS results (QM2006)
New data on antiparticle/particle ratios Identified particle spectra for 62.4 GeV Au+Au Event-by-event v2 measurement and flow fluctuations
Two-particle correlations and cluster size
![Page 33: Charged particle multiplicity studies with PHOBOS Birger Back Argonne National Laboratory for the PHOBOS Collaboration](https://reader030.vdocuments.mx/reader030/viewer/2022032723/56649f575503460f94c7c340/html5/thumbnails/33.jpg)
33
New Data: antiparticle/particle ratios
PHOBOS, QM2006
200, 62.4 GeV Cu+Cu 200 GeV Cu+Cu and Au+Au
Energy dependence for Cu+Cu System dependence at 200 GeV
![Page 34: Charged particle multiplicity studies with PHOBOS Birger Back Argonne National Laboratory for the PHOBOS Collaboration](https://reader030.vdocuments.mx/reader030/viewer/2022032723/56649f575503460f94c7c340/html5/thumbnails/34.jpg)
34
Identified particle spectra for 62.4 GeV Au+Au
First published identified spectra for 62.4 GeV Au+Au at RHIC(down to very low pT, a unique PHOBOS measurement)
blast-wave fits
PHOBOS, nucl-ex/0610001Accepted for PRC
![Page 35: Charged particle multiplicity studies with PHOBOS Birger Back Argonne National Laboratory for the PHOBOS Collaboration](https://reader030.vdocuments.mx/reader030/viewer/2022032723/56649f575503460f94c7c340/html5/thumbnails/35.jpg)
35
New Analysis: event-by-event v2 measurement
Measure v2 on an event-by-event basis
Average and compare to our standard analysis
Agreement with both hit and track based PHOBOS results
200 GeV Au+Au
PHOBOS, QM2006; arXiv:nucl-ex/0608025Submit to PRL this week
![Page 36: Charged particle multiplicity studies with PHOBOS Birger Back Argonne National Laboratory for the PHOBOS Collaboration](https://reader030.vdocuments.mx/reader030/viewer/2022032723/56649f575503460f94c7c340/html5/thumbnails/36.jpg)
36
Event-by-event flow: fluctuations
PHOBOS, QM2006Submit to PRL this week
v2 fluctuations
mirror
part fluctuations
(v2)/<v2> and (part)/<part> in 200 GeV Au+Au Collisions
PHOBOS part prediction
PHOBOS v2 result
90% CL
MC with nofluctuations
![Page 37: Charged particle multiplicity studies with PHOBOS Birger Back Argonne National Laboratory for the PHOBOS Collaboration](https://reader030.vdocuments.mx/reader030/viewer/2022032723/56649f575503460f94c7c340/html5/thumbnails/37.jpg)
37
Effective cluster size analysis
On average, particles produced in clusters with a size of 2-3.
Interesting centrality dependence – compare to other systems
p+p
scale error
2
Ke
ff =
eff
ecti
ve c
lust
er s
ize
PHOBOS, QM2006
![Page 38: Charged particle multiplicity studies with PHOBOS Birger Back Argonne National Laboratory for the PHOBOS Collaboration](https://reader030.vdocuments.mx/reader030/viewer/2022032723/56649f575503460f94c7c340/html5/thumbnails/38.jpg)
38
Summary and conclusion
Multiplicity
– PHOBOS have performed complete charged particle multiplicity measurements for Au+Au, Cu+Cu, d+Au, and p+p collisions
– Systen size dependence
– ‘Complete’ pseudorapidity distributions Midrapidity multiplicity
– Factorization of centrality and energy dependencies Limiting fragmentation – extended longitudinal scaling
– Seen for Au+Au, Cu+Cu, and d+Au
– Also observed in flow observables Total charged particle multiplicity
– Nch/Npart constant with centrality
– ‘Universality’ – compared to elementary e+e- collisions Future: Finish up many analysis and reviews
![Page 39: Charged particle multiplicity studies with PHOBOS Birger Back Argonne National Laboratory for the PHOBOS Collaboration](https://reader030.vdocuments.mx/reader030/viewer/2022032723/56649f575503460f94c7c340/html5/thumbnails/39.jpg)
39
Why mid-rapidity?
Emphasize producedor scatteredparticles
Triple Gaussianfit function
200 GeV Au+Au 0-6% central
![Page 40: Charged particle multiplicity studies with PHOBOS Birger Back Argonne National Laboratory for the PHOBOS Collaboration](https://reader030.vdocuments.mx/reader030/viewer/2022032723/56649f575503460f94c7c340/html5/thumbnails/40.jpg)
40
System size dependence - Au+Au vs. Cu+Cu
![Page 41: Charged particle multiplicity studies with PHOBOS Birger Back Argonne National Laboratory for the PHOBOS Collaboration](https://reader030.vdocuments.mx/reader030/viewer/2022032723/56649f575503460f94c7c340/html5/thumbnails/41.jpg)
41
Centrality dependence 200 GeV
![Page 42: Charged particle multiplicity studies with PHOBOS Birger Back Argonne National Laboratory for the PHOBOS Collaboration](https://reader030.vdocuments.mx/reader030/viewer/2022032723/56649f575503460f94c7c340/html5/thumbnails/42.jpg)
43
Cu+Cu elliptical flow – eccentricity scaling
PHOBOS, QM2006