STAR @ Laboratory of Particle Physics, JINR

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STAR @


Laboratory of Particle Physics, JINR

Present, Past and Future

activities

Zulkarneev R.Ya.


Outline


STAR Detector
Overview


Past



BEMC Creation



Study of


BEMC performances


BEMC : Potentialities inherent


Present


current scientific programme &


STAR White Paper




Heavy Flavour Physics



Femtoscopy(HBT) group results



Soft Photon Physics


Spin Physics



Software


Future

STAR Detector overview


120 separate modules


or 4800 towers:



φ
,
∆η

= 0.05,0.05

LPP:
BEMC Creation (1999
-
2004)

Barrel Electromagnetic Calorimeter (
BEMC)

hardware :





assembling of the
modules




design and construction of the
PMT
-
boxes




design and manufacture of the
optical

system



Total
contribution

of LPP STAR group

in the BEMC creation

was
estimated in terms of money as much as







US 931 K $


On January 2005

the Technical Advisory Committee of STAR
collaboration has reviewed the BEMC Project and concludes that

BEMC

has met cost, scope, and schedule, and
is




ready to operate
.



BEMC
:
potentialities inherent




Hot & dense matter at RHIC



Possibilities for search of new kind

QGP
signals through observation:





Gammas &




Electrons


J/
ψ

, Upsilon and



other states






Proton Spin problem



Access to investigate the unique
processes with production of the




direct photons,


Drell
-
Yan’s pairs,


W
-

and Z
-
bosons









EMC adds a new triggering capabilities
:

high P
t

, Jets , J/
ψ
,…

LPP:Study of BEMC performances
(2001
-
2003)

QM2004 : “Performance of the STAR Barrel Electromagnetic Calorimeter”


Typical MIP spectrum



Figure 21. On this plot you can see relative SMD electron
registration efficiency. This was done by demanding at least 2
SMD hits in both SMD planes directly under the projected track.
Also deposition of at least 200 Mev was requred. SMD efficiency
was studied on a part of electron sample selected using a narrow
cut on dEdx in a “safe” region (TPC) + BEMC cut applied.



E
γ
,e = (1.0
-

50) GeV



∆E/E ~ 0.16/√E GeV



η

= [1;
-
1]
φ

= [0;2
π
]

The STAR Collaboration’s Critical Assessment of theEvidence from
the RHIC Collisions (
STAR

White Paper
, 14 January 2005
)





What are the critical needs from future experiments?


...
measure the nuclear modification factors for charmed meson production, to
look for the prediction to reduce energy loss for heavy quarks…


…look for the extra suppression of charmonium compared to open charm…


…develop thermometers for early stage of collisions …well before chemical
freezeout


central AuAu
-
interactions at RHIC produce

dence, rapidly
thermalizing matter

characterized by: 1) initial energy densities
above the critical values predicted by lattice GCD for
establishment of a QGP;2) nearly ideal fluid flow established most
probably at a stage preceding hadron formation; and 3)opacity to
jets.




We pose a set

of
important open questions, and suggest
additional measurements…
which should be addressed before there
can be a compelling basis

to conclude that we have

definitively
formed thermalized, deconfinement matter at RHIC.


I.
I
nvestigation of inclusive
high P
T

non
-

photonic electron spectra

in
PP
-
,
dAu
-

and AuAu
-

collisions at RHIC energies.

Why high P
T

electron spectra?



Heavy Flavour States

(HFS) are accessible through


their


b, c


e + X


leptonic channel decays.

That



is direct way to

Heavy Flavour Physics

study


II.
Search of direct soft photons produced in dAu
-

and AuAu
-

collisions at
200GeV
(Soft Photnos Physics)


The40
-
160 MeV photons

are accessible at STAR TPC


Do its serve

as a kind of Thermometer for early


stages of the matter producted at RHIC ?



III.
Study of
two particle correlation functions in AuAu
-

collisions at

RHIC
energies
(HBT
-
femtometry technics)
.





IV.
Study of transverse spin structure of the proton.
(Spin physics)




LPP: Current Physics Programme


1.

Investigation of high Pt non
-
photonic electron spectra in pp
-
, dA
-

and


AuAu
-

collisions at 200 GeV







Pt

:

(1.0


10.0)GeV ;

BEMC , TPC and STAR
triggering systems



η

:

[1.0 ,
-
1.0]



Goals
:



cross
-
sections of (cˉc)
-
, (b‾b)
-
states production
;


info for HFS
-
triggering

;



to look at the

suppression

of the

heavy flavour states



producted in hot & dense matter ;


J/
ψ
-

production


in long time prospect






Physics Working Group
:
Heavy flavour



Status
:

data analysis & publication of the first results





LPP
:
Heavy Flavour
Physics



p + p

d + Au




200 GeV
pp


e + X


σ
(c
¯

,
c) µb

=
1290


210


400


σ
(b
¯
,
b) µb

=
5.45
±
0.97
±
2.0





LPP
:Heavy Flavor Physics

Heavy (c
-
,b
-
) quarks suppression:





is theoretically more
well controlled



measurement of it provides a critical
check
of partonic energy

loss nature


Transition from hadronic to QGP
is

strong
sensitive to

number of active
quark flavours and their mass


provides
reference data

for studies
of color screening via quarconium
suppression in future

LPP:
Heavy Flavor Physics

(continuation)

a) inclusive electron ((e
-
+e
+
)/2) spectra for pp, dAu
and AuAu collisions at

s
NN
=200 GeV.

b)inclusive to background ratio for pp and 0
-
5%
most central AuAu collisions

c) invariant e
+
e
-

mass spectrum


Non
-
photonic electrons:


semileptonic charm & beauty decays


Drell
-
Yan processes


Photonic electrons:


photon conversion,
γ → e
+
e
-


π
0
and η Dalitz decays, π
0
→γe
+
e
-

Non
-
photonic electron spectra for pp, dAu and
AuAu collisions at

s
NN
=200 GeV

LPP:
Heavy Flavor Physics

(continuation)


The modification factor, R
AA

for dAu,
and AuAu collisions at

s
NN
=200 GeV




Strong suppression

of non
-
photonic


electrons has been observed in


Au+Au,
increasing with centrality




R
AA
~ 0.2
-
0.3 for pT > 3 GeV/c




suggests large energy loss of


heavy quarks !



to be published Phys.Rev.Lett.

two person of LPP group are the
principal authors of the publication!


LPP
:Femtometry
-
HBT group results




II.

Study of the correlation functions of “
exsotic pair particles




The LPP
-
France
-
Slovac
-
Czech Rep.group has been done the
study of proton
-
lambda correlation in AuAu
-
collisions at RHIC




Being based on the known proton
-
lambda scattering lengths
,
the average

size

of
the proton and lambda sources was found to be ~3 fm,

close to

the

size of
the proton source

determined from proton
-
proton correlation function.


For proton
-
antilambda and antiproton
-
lambda systems, the
correlation functions have been measured for the first time and
the corresponding spin averaged scattering length was estimated
.



A new perspective is open:




the correlation study of particle scattering in the systems


which can hardly be accessible by other nuclear means
.


LPP:
Soft Photon Physics

III.

Search of the direct soft photons in dAu
-
,AuAu
-
collisions at 200GeV





P
γ

:
(40


160) MeV ; TPC

and

STAR
triggering systems.



η
γ

:
[0.7 ,
-
0.7]





Ultimate goal
:
tests for theoretical model predictions;


receiving the data

to estimate

the temperature of


thermalized stage(s) of the collision fireball;




Physics Working Group

:
Spectra



Status of the initial


stage of work:
studies of background

-

inclusive soft gamma


spectra



produced in AuAu
-
, dAu
-

collisions at 200 GeV

-


in progress

Pre
-
equilibrium Parton
Cascade

EM & Weak Decay

after freeze
-
out

QGP

Hadron

Gas

PROMT DIRECT PHOTONS

THERMAL

DIRECT PHOTONS

background

PHOTONS

What does mean “DIRECT “PHOTONS

direct

photons =
AuAu
-
inclusive

photons


T ( dAu
-
inclusive

photons
)

mainly hard gammas


E
γ

> 1 GeV

more soft gammas


E
γ

< 1GeV

Soft photons:theoretic predictions




there are a lot of model predictions


for photon spectra in soft energy region




thermal radiation sensitive :




to initial state temperature;




degrees of freedom and EOS;




little interaction with surrounding


matter


But


experimentally very challenging:




large background of photons from


hadron decays(neutral mesons)


LPP:
Spin Physics


IV.

The study of reactions:
PP↑→ (
π
+

,

π

-
)+ X and PP → (
π
+

,
π

-

)+X


at 200 GeV



A complete quark spin density matrix is given by
three quark distributions

:






f1 (x)

-
related with the longitudinal momentum quarks in nucleon;




g1 (x)

-
related with helicity distribution in polarized nucleon and




h1 (x)

-

related with
transverse spin distribution

(correlation between


left
-

and right quarks ) in the transverse polarized nucleon.


SPIN crisis can’t be resolve
on compelling base


without

the h1(x)

measurement




Goal
:

observation of dependence of high Pt hadrons pair production


plane on the incident proton beam polarisation in order to get


transverse

spin distribution in the proton (
transversity
)




Status:

proposal preparation in progress!



LPP: STAR Software Development


NEOSTAR cluster



STAR framework


Offline DB mirror


STAR Database Browsers


STAR DB Browser


BEMC Browser


EEMC Browser


STAR Content Management System


Drupal


STAR GRID applications


Job Tracker (WS)


Job submission GUI


Log4c++, WS appender

BEMC, BSMD, EEMC database browser visualization

STAR Content Management System

Offline database browser

Future


More Physics!




J/Psi and oniums...



Direct Photons :


more statistics and


understanding of the background puzzle



Participation in the STAR upgrade in order


to enhance soft gamma photon efficiency registration,


to extend energy interval up to 1 GeV



PROPOSAL in PROGRESS



Spin Physics



More Software!




Grid Computing: Job Tracker Web Service



HEP Visualization