“Study the Low Mass Dielectron Production in
Relativistic Heavy-Ion Collisions at RHIC-STAR”
SUPPLEMENTARY PROPOSAL
TO
“THE EXPERIMENTAL STUDY OF THE PHASE STRUCTURE OF
STRONGLY INTERACTING MATTER”
Grant: DE-FG02-88ER40412
Prepared by
Wei Xie
Department of Physics
Purdue University
West Lafayette, Indiana 47907
September, 2010
Project Proposal Period: January 1, 2011 – December 31, 2013
1
Table of Contents
1.
INTRODUCTION............................................................................................................................... 3
2.
RESEARCH PLAN .......................................................................................................................... 5
2.1.
2.2.
2.3.
2.4.
2.5.
2.6.
2.7.
2.8.
SUMMARY OF THE RESEARCH PLAN AND THE TIMELINE OF DELIVERING THE RESULTS....... 5
MEASUREMENT OF DIELECTRON PRODUCTION IN 200 GEV AU+AU COLLISIONS ........................ 5
MEASUREMENT OF DIELECTRON PRODUCTION IN 62.4 GEV ENERGY AU+AU COLLISIONS ......... 9
MEASUREMENT OF DIELECTRON PRODUCTION IN 39 GEV ENERGY AU+AU COLLISIONS ...........11
MEASUREMENT OF DIELECTRON PRODUCTION IN 200 GEV U+U COLLISIONS ............................13
MEASUREMENT OF DIELECTRON PRODUCTION IN P+P COLLISIONS .............................................14
FUTURE PERSPECTIVE ...............................................................................................................14
BUDGET REQUESTS .....................................................................................................................15
3.
CURRENT SUPPORT ......................................................................................................................16
4.
EXISTING RESOURCES .................................................................................................................16
5.
BIOGRAPHICAL SKETCHS ..........................................................................................................17
6.
STUDENTS ........................................................................................................................................19
8. LIST OF TALKS AND PUBLICATIONS ...........................................................................................19
8.1. INVITED TALKS IN THE CONFERENCE AND WORKSHOPS IN THE PAST THREE YEARS ...........................19
8.2.
LIST OF PUBLICATIONS IN REFERRED JOURNAL IN THE PAST THREE YEARS ...............................20
REFERENCES ............................................................................................................................................27
2
1. INTRODUCTION
The objective of this proposal is to measure the enhancement of the dielectron
production in the low mass region (mee < 1.2 GeV/c2) in heavy-ion collisions and find out
where the enhancement starts to appear as a function of the collision energies using the
STAR detector at the Relativistic Heavy Ion Collider (RHIC). Dielectron production is
not affected by strong interaction and is therefore considered as an ideal probe to study
the chiral symmetry restoration and the properties of the QCD medium during its
spacetime evolution. The research will include measuring dielectron yield in Au+Au
collisions at √𝑠𝑛𝑛 = 200 𝐺𝑒𝑉 and lower energies.
At high temperature (T > Tc, where Tc ~ 170MeV) or high energy density ( >
1GeV/fm3), quarks and gluons were expected to move around like a free gas and to no
longer be confined inside the hadrons [1] because of the significantly weakened
interactions among them due to the QCD “asymptotic freedom”. In analogy to the
conventional plasma in atomic physic, this state of matter with deconfined quarks and
gluons is named as the “Quark Gluon Plasma” (QGP). However, lots of evidences
suggests that the medium created at RHIC has a ratio of shear viscosity over entropy
close to the quantum limit and is therefore more like a “perfect fluid” with strong
interactions among the constituents. The future RHIC physics programs will clearly focus
on the detailed studies of the medium properties. Direct measurement of medium
temperature and understanding chiral symmetry restoration are some of the important
steps towards this direction. At around the same time when the phase transition from
hadron gas to QGP happens, chiral asymmetry is expected to be restored as a result of the
significant reduction of quark condensate masses [2] or broadening of the vector mass
spectra with little shift of mass peak position [3]. All detailed studies require progress on
theoretical modeling as well as the precision measurements from experiment using
different probes. Dielectron is one of the ideal probes to carry on these studies. Compared
to hadrons, electrons have little interaction with the medium and can therefore travel
through the medium while keeping most of the original information untouched. This
feature enables us to study the chiral symmetry restoration as well as the properties of the
medium during space-time evolution of the system.
The most interesting electrons are the ones coming from the thermal radiation of the
QGP as well as those from low mass vector meson decay. In the QGP phase, quark and
antiquark in the thermalized medium can annihilate each other to produce thermal
photons which carry the direct information of the medium initial temperature. Production
of real photons is always accompanied by the production of virtual photons that
subsequently decay into dielectrons. We can therefore derive the real photon yield
through measuring the yield of virtual-photon-decay dielectrons according to
𝑑 2 𝑌𝑒𝑒 ⁄𝑑𝑚2 = 2𝛼 ⁄3𝜋 ∙ 𝐿(𝑚)⁄𝑚 ∙ 𝑆(𝑚, 𝑞) ∙ 𝑑𝑌𝛾 , where 𝐿(𝑚) = √1 − 4𝑚𝑒2 /𝑚2 ∙ (1 +
2𝑚𝑒2 /𝑚2 ), Yee and Yγ are respectively the yield of dielectron and photons, me is the
electron mass, m is the di-electron mass, α is the fine structure constant and s(m,q) is the
ratio of virtual photon yield over that of real photons. Compared to the conventional
method of measuring real photons, this method leads to much higher S/B at 1 < pT< 3
GeV/c where hadronic decay photon dominate [4]. Dielectrons decay from light vector
mesons, especially ρ meson have long been considered as an ideal tool to study early
stage of the medium and the chiral symmetry restoration. The dielectron from ρ meson
3
decay comes mainly from ππ annihilation [5] ( 𝜋 + 𝜋 − → 𝜌 → 𝑒 + 𝑒 − ), and is expected to
dominate the low mass dielectron production. Because the 𝜌 meson has a lifetime of
~1.3 fm/c, which is much shorter than that of the medium, we can study effect of the
chiral symmetry restoration on the reconstructed mass peak position and width of ρ
meson and compare with the prediction of different theoretical models.
Large enhancement of the low mass dilepton production in heavy-ion collisions was
first discovered by the CERES [6] and HELIOS/3 [7] experiments at CERN SPS and was
attributed mainly to the in-medium modification of the ρ meson production in the hadron
gas as well as the regeneration of ρ meson from ππ annihilations [8]. This understanding
was further strengthened by the new measurements from CERES [9], HADES [10] and
especially the high precision measurements of dimuon production in In+In collisions at
√𝑠𝑛𝑛 = ~20 𝐺𝑒𝑉 from NA60 [11]. NA60 results can be well described by the
mechanism of broadened ρ meson from ππ annihilation in the hot and dense hadronic
medium, with small contribution from the QGP thermal radiation [12]. At RHIC, with
about ten times higher collision energy, the measurements of dielectron production in
√𝑠𝑛𝑛 = 200 𝐺𝑒𝑉 Au+Au collision from PHENIX experiment shows a large
enhancement [13] in the broad region of mee = 0.15-0.75 GeV/c2. Unlike the results from
CERN SPS, this enhancement is consistent with the dielectron production from virtual
direct photons [4] indicating the source of the enhancement is dominated by the QGP
thermal radiation. The result, however, cannot be understood by any available theoretical
models since the QGP thermal radiation is expected to dominate the region of
1.2<mee<2.9GeV/c2 instead of the low mass region [14]. It would be essential to have
another independent measurement of this important observation to as a cross check. In
the mean time, since the similar effect is not observed in CERN SPS measurements, it
would be essential to find out when the enhancement starts to appear through the low
energy scan program at RHIC.
We propose to study low mass dielectron production using the STAR detector at
RHIC. Since the 2010 RHIC Au+Au run, STAR has completed the implementation of a
Time-Of-Flight detector (TOF). TOF has excellent capability of electron identification at
pT < 1.0 GeV/c. At pT > 1.0 GeV/c, together with STAR Time-Projection-Chamber
(TPC), STAR Electromagnetic Calorimeter (EMC) can be used to identify electron very
efficiently. We can therefore measure low mass dielectron production yield at both low
and high pT. In the mean time, STAR has been carrying on the low energy scan program
to search for the phase transition critical point. We can take this opportunity to study
dielectron production in Au+Au collision between √𝑠𝑛𝑛 =20 GeV and 200 GeV, with the
goal to find out where the enhancement starts to appear. We expect that the outcome of
these studies will provide crucial inputs to the understanding of QGP medium and the
chiral symmetry restorations.
This research will be carried out by the two graduate students requested in this
proposal, under the supervision of Wei Xie.
4
2. RESEARCH PLAN
2.1.
Summary of the Research Plan and the Timeline of Delivering the Results
In year 2011 and 2012, we plan to recruit two students to work on measuring low
mass dielectron production in 200 GeV and 62.4 GeV Au+Au collisions. Both datasets
have already been collected by STAR during RHIC 2010 run. The analysis on 200 GeV
data is to cross check the PHENIX discovery of the large enhancement in the low mass
region, while the analysis on the data from 62.4 GeV collisions, which is in-between the
CERN SPS energy (~20 GeV) and RHIC full energy, is the first step to figure out where
the enhancement starts to appear as a function of collision energies. With the existing
200 GeV Au+Au dataset, we expect to observe the low mass dielectron enhancement in
inclusive invariant mass spectrum and also quantify the enhancement up to pT = 0.5
GeV/c. With the 62.4 GeV Au+Au dataset, we will be able to provide a significant
measurement at mee < 0.4GeV/c2 up to pT = 2.0 GeV/c. We plan to accomplish the two
data analyses and publish the results in refereed journals in two years taking into account
the training time of the students.
In year 2013, one student is expected to continue measuring dielectron production in
39 GeV Au+Au collisions. This will further narrow down the region where the dielectron
enhancement starts to happen. The other student will measure dielectron production in
200 GeV U+U collisions. The 39 GeV datasets has already been collected in STAR in
RHIC 2010 run. The RHIC Physics Advisory Committee (PAC) has recommended the
200 GeV U+U collisions in run 2012. In case the U+U program is not possible, the PAC
recommends 7 weeks of Au+Au runs which provides higher luminosity than in run2010.
In this case, the student will analyze the Au+Au data. With the existing 39 GeV Au+Au
datasets, we expect a significant measurement at mee < 0.4GeV/c2 up to pT = 2.0 GeV/c.
With the run 2012 U+U or Au+Au collisions, the measurement precision will be better
than that of run 2010. We plan to accomplish both analyses and publish the results in
about one and half years.
2.2.
Measurement of Dielectron Production in 200 GeV Au+Au collisions
In RHIC run 2010, STAR collected 355 million minimum-bias events in 200 GeV
Au+Au collisions. Using the HIJING event generator [15], we estimated the statistical
significance of the dielectron production in the low mass region. The combinatorial
background in the low mass region is dominated by dielectrons from π0, η, η’ Dalitz
decays as well as the electrons from photon conversions which are not included in the
HIJING simulation. Since the kinematics of electron pairs from photon conversion and π0
Dalitz decay is quite similar, we increase the π0 Dalitz decay branching ratio by a factor
of 2.5 to take into account the material thickness in STAR tracking system. The other
signals included in the simulation are 𝜌 → 𝑒 + 𝑒 − , 𝜔 → 𝑒 + 𝑒 − , 𝜙 → 𝑒 + 𝑒 − and electron
pairs from the correlated heavy flavor hadron and antihadron production (𝑐𝑐̅/𝑏𝑏̅ ). We do
not take into account the contribution from 𝜔 → 𝜋 0 𝑒 + 𝑒 − and 𝜙 → 𝜂𝑒 + 𝑒 − due to the
limitation of the event generator. The electron identification efficiency is assumed to be
100% in all projections of this proposal.
5
Figure 1 upper panel shows the simulated invariant mass spectrum of e+e- pairs using
355 million minimum-bias 200 GeV Au+Au collisions generated from HIJING. The
dielectron signal is represented as the red histogram. The spectra of opposite charge signs
electron pairs (unlike-sign foreground) and combinatorial background are represented as
the black and the blue histograms. The sources of signal from various hadron decays are
also included as shown in the figures. The lower panel shows the significance of the
dielectron signal as a function of the e+e- mass. At 0.15 < 𝑚𝑒𝑒 < 0.75 𝐺𝑒𝑉/𝑐 2 , we
expect to have a measurement of significance of 7-15 with the existing dataset. This will
Figure 1: The upper panel shows the dielectron invariant mass spectrum in STAR detector
acceptance from 300 million minimum-bias Au+Au collisions at √𝒔𝒏𝒏 = 𝟐𝟎𝟎 𝑮𝒆𝑽 produced
from HIJING event generator. Included in the panel are the unlike-sign foreground (back
histogram), combinatorial background (blue histogram), dielectron signal (red histogram) and
various sources of signals represented by different symbols described in the figure. The low panel
shows the significance of the dielectron signal in different electron pair mass region.
be further improved after taking into account of the large enhancement of the dielectron
production in this mass region in data. Figure 2 upper-left panel shows the PHENIX
measurements of the dielectron invariant mass spectrum in 200 GeV Au+Au collisions
[13] together with the expectation from normal hadron decays (cocktail). The lower-left
panel shows the ratio of the measured dielectron yields over the cocktail. The cocktail
can describe the data very well in all mass range except that there is an enhancement of
about a factor of 2-10 at 0.15 < 𝑚𝑒𝑒 < 0.75 𝐺𝑒𝑉/𝑐 2 in data. Since the combinatorial
6
background is dominated by electrons from photon conversion and π0 Dalitz decay, the
large enhancement will increase the projected signal significance in Figure 1 by a factor
of 2-10. We should clearly see the signal enhancement in the inclusive dielectron
spectrum using the 200 GeV Au+Au dataset collected at STAR.
The right panel of Figure 2 shows the PHENIX measurement of delectron invariant
mass spectra in 200 GeV minimum bias Au + Au collisions in different dielectron pT
regions. The large enhancement appears in all pT up to 5GeV/c, beyond which the data is
out of statistics. The projections of the similar measurements using STAR data are shown
in Figure 3, where each panel presents the simulated dielectron invariant mass spectrum
(upper) as well as the signal significance as a function of electron pair mass (lower) in
different pT region in STAR detector acceptance from 300 million minimum-bias Au+Au
collisions at √𝑠𝑛𝑛 = 200 𝐺𝑒𝑉 produced from HIJING event generator. At mee <
0.4GeV/c2, the projected signal significance at pT < 4 GeV/c are above 5.0. The large
enhancement of data will boost the significance above 10. At mee > 0.4GeV/c2, the
projected significance is smaller than 5.0 at pT > 2.0 GeV/c, making it difficult to obtain a
conclusive measurement. At pT > 5GeV/c, the current dataset runs out of statistics.
Figure 2: The upper left panel shows the PHENIX measurement of dielectron invariant mass
spectrum in PHENIX detector acceptance in minimum-bias Au+Au collisions at √𝑠𝑛𝑛 =
200 𝐺𝑒𝑉 . The cocktail spectra from the decays of light hadrons and correlated decays of charm,
bottom and Drell-Yan are also included and are represented by different symbols described in the
figure. The bottom panel shows the ratio of data over the cocktail spectra. The systematic
uncertainties of the data are shown as boxes. The uncertainty of the cocktail spectrum is shown as
band around one. The right panel shows the delectron invariant mass spectra in 200 GeV
minimum bias Au + Au collisions in different pT ranges. The solid curves represent the cocktail
spectrum, where the contribution from charm is calculated through pythia using the cross section
from [16] scaled by Ncoll.
7
Figure 3: Each panel shows the dielectron invariant mass spectrum (upper) as well as the signal
significance as a function of electron pair mass (lower) in different pT region in STAR detector
acceptance from 300 million minimum-bias Au+Au collisions at √𝒔𝒏𝒏 = 𝟐𝟎𝟎 𝑮𝒆𝑽 produced
from HIJING event generator. The unlike-sign foreground and combinatorial background are
represented as the black and blue histograms, respectively. The dielectron signal is represented as
the red histogram. The pT regions are indicated in each panel.
8
2.3.
Measurement of Dielectron Production in 62.4 GeV Energy Au+Au collisions
In RHIC run 2010, STAR also collected 140 million minimum-bias events in Au+Au
collisions at √𝑠 = 62.4 𝐺𝑒𝑉. We estimated the statistical significance of the dielectron
production in the low mass region using HIJING event generator following the same
procedure as described in Sec.2.2.
Figure 4: The upper panel shows the dielectron invariant mass spectrum in STAR detector
acceptance from 140 million minimum-bias Au+Au collisions at √𝒔𝒏𝒏 = 𝟔𝟐. 𝟒 𝑮𝒆𝑽 produced
from HIJING event generator. Included in the panel are the unlike-sign foreground (back
histogram), combinatorial background (blue histogram), dielectron signal (red histogram) and
various sources of signals represented by different symbols described in the figure. The low panel
shows the significance of the dielectron signal in different electron pair mass region.
Figure 4 upper panel shows the simulated invariant mass spectrum of e+e- pairs using
140 million minimum-bias 62.4 GeV Au+Au collisions generated from HIJING. The
dielectron signal is represented as the red histogram. The spectra of opposite charge signs
electron pairs (unlike-sign foreground) and combinatorial background are represented as
the black and the blue histograms. The sources of signal from various hadron decays are
also included as shown in the figures. The lower panel shows the significance of the
dielectron signal as a function of the e+e- mass. At 0.15 < 𝑚𝑒𝑒 < 0.75 𝐺𝑒𝑉/𝑐 2 , we
expect to have a measurement of significance of 3-10 with the existing dataset. This will
be further improved if there is a enhancement of the low mass dielectron production at
62.4 GeV/c. In either case, we should be able to have a significant measurement on the
enhancement at mee
The projections of the pT dependent dielectron spectrum using STAR data are shown
in Figure 5, where each panel shows the simulated dielectron invariant mass spectrum
(upper) as well as the signal significance as a function of electron pair mass (lower) in
9
different pT region in STAR detector acceptance from 140 million minimum-bias Au+Au
collisions at √𝑠𝑛𝑛 = 62.4 𝐺𝑒𝑉 produced from HIJING event generator. At mee <
0.4GeV/c2, the projected signal significance at pT < 2.0 GeV/c are above 5.0. This can be
further improved if the enhancement also appears in the 62.4 GeV Au+Au collisions. For
example, in case the enhancement factor is two, the measurement will be 5 standard
deviations above the cocktail. At mee > 0.4GeV/c2, the projected significance is smaller
than 3.0 and it’s not likely to have a significant measurements.
Figure 5: Each panel shows the dielectron invariant mass spectrum (upper) as well as the signal
significance as a function of electron pair mass (lower) in different pT region in STAR detector
acceptance from 140 million minimum-bias Au+Au collisions at √𝒔𝒏𝒏 = 𝟔𝟐. 𝟒 𝑮𝒆𝑽 produced
from HIJING event generator. The unlike-sign foreground and combinatorial background are
represented as the black and blue histograms, respectively. The dielectron signal is represented as
the red histogram. The pT regions are indicated in each panel.
10
2.4.
Measurement of Dielectron Production in 39 GeV Energy Au+Au collisions
In RHIC run 2010, STAR also collected 250 million minimum-bias events in Au+Au
collisions at √𝑠 = 39 𝐺𝑒𝑉. We estimated the statistical significance of the dielectron
production in the low mass region using the HIJING event generator following the same
procedure as described in Sec.2.2.
Figure 6: The upper panel shows the dielectron invariant mass spectrum in STAR detector
acceptance from 250 million minimum-bias Au+Au collisions at √𝒔𝒏𝒏 = 𝟑𝟗 𝑮𝒆𝑽 produced from
HIJING event generator. Included in the panel are the unlike-sign foreground (back histogram),
combinatorial background (blue histogram), dielectron signal (red histogram) and various sources
of signals represented by different symbols described in the figure. The low panel shows the
significance of the dielectron signal in different electron pair mass region.
Figure 6 upper panel shows the simulated invariant mass spectrum of e+e- pairs using
250 million minimum-bias 39 GeV Au+Au collisions generated from HIJING. The
dielectron signal is represented as the red histogram. The spectra of opposite charge signs
electron pairs (unlike-sign foreground) and combinatorial background are represented as
the black and the blue histograms. The sources of signal from various hadron decays are
also included as shown in the figures. The lower panel shows the significance of the
dielectron signal as a function of the e+e- mass. At 0.15 < 𝑚𝑒𝑒 < 0.75 𝐺𝑒𝑉/𝑐 2 , we
expect to have a measurement of significance of 5-13 with the existing dataset.
Therefore, whether there is a enhancement of low mass dielectron or not, we should be
able to have a significant measurement in the low mass region.
The projections of the pT dependent dielectron spectrum using STAR data are shown
in Figure 7, where each panel shows the simulated dielectron invariant mass spectrum
11
(upper) as well as the signal significance as a function of electron pair mass (lower) in
different pT region in STAR detector acceptance from 300 million minimum-bias Au+Au
collisions at √𝑠𝑛𝑛 = 39 𝐺𝑒𝑉 produced from HIJING event generator. The situation is
similar as in 62.4 GeV measurements, i.e. at mee < 0.4GeV/c2, the projected signal
significance at pT < 2.0 GeV/c are above 5.0. At mee > 0.4GeV/c2, the projected
significance is smaller than 3.0, making it difficult to provide a significant measurement.
Figure 7: Each panel shows the dielectron invariant mass spectrum (upper) as well as the signal
significance as a function of electron pair mass (lower) in different pT region in STAR detector
acceptance from 250 million minimum-bias Au+Au collisions at √𝒔𝒏𝒏 = 𝟑𝟗 𝑮𝒆𝑽 produced from
HIJING event generator. The unlike-sign foreground and combinatorial background are
represented as the black and blue histograms, respectively. The dielectron signal is represented as
the red histogram. The pT regions are indicated in each panel.
12
2.5.
Measurement of Dielectron Production in 200 GeV U+U collisions
The current recommendation from RHIC PAC is that in run 2012, RHIC will run 200
GeV U+U or Au+Au collisions for 7 weeks. Compared to the gold nucleus, Uranium
nucleus has a larger A value and a prolate shape. This will enable RHIC to produce a
matter with higher densities through U+U collisions than that from Au+Au collisions.
Figure 8 shows the energy density (ε0) as a function of the centrality [17] in Au+Au and
U+U collisions. The peak energy density in U+U collisions will be 62% higher than that
of Au+Au. It would be very interesting how the low dielectron changes with higher
energy density. If the enhancement is indeed coming from the QGP thermal radiation, we
expect a measurement of higher temperature from low mass dielectrons.
Figure 8: Energy density (ε0) in full-overlap U+U collisions and in different centrality of Au+Au
collisions.
In run 2012, the current projection of the weekly integrated luminosity in U+U
collisions from RHIC Collider-Accelerator department is 400-1250 μb-1/week. In one 7week run, the delivered luminosity will be 2-8 nb-1, which is ~1.5-6 time higher than that
of the Au+Au collisions in 2010. We therefore expect a very good dielectron
measurement in U+U collisions from run 2012.
In case RHIC decide to run Au+Au collisions, the projection on the weekly delivered
luminosity is 650-1300 μb-1/week. In a 7-week run, RHIC will deliver 2-5nb-1 of Au+Au
collision which is 1.5-4.0 times better than that of run2010. This will enable us to
measure the low mass dielectron in Au+Au collisions with better accuracy.
13
2.6.
Measurement of Dielectron Production in p+p collisions
To quantify the dielectron enhancement in Au+Au collision, we need to do the same
measurements in p+p collisions as a reference to make sure our calculation of cocktail is
correct. Figure 9 shows the STAR measurement of dielectron invariant mass spectrum in
200 GeV p+p collisions using data from run 2009 [18]. The result is from 107 million
minimum-bias p+p collisions and can be further improve by analyzing all 300 million
minimum-bias events accumulated in the run. We can clearly see ω and 𝜙 signals, except
that the accuracy at 0.3 < mee < 0.75 GeV/c2 need much improvements. There is no long
p+p runs in 200 GeV, 62.4 GeV and 39 GeV before run 2012 from the PAC
recommendation. However, if our results show that long p+p runs in different collisions
energies are essential, we will put forward our request to the PAC through the
collaboration management.
Figure 9: dielectron invariant mass spectrum in STAR detector acceptance from 107 million
minimum-bias p+p collisions at √𝒔𝒏𝒏 = 𝟐𝟎𝟎 𝑮𝒆𝑽
2.7.
Future Perspective
In run 2014, STAR will accomplish the Heavy Flavor Tracker (HFT) [19] silicon
vertex detector. We will then be able to reject photon conversions outside of beam-pipe
by requiring electron tracks to consist of hits from all silicon layers. This will
significantly reduce the combinatorial background and therefore increase the signal
significance in the low mass dielectron measurements. In the mean time, the HFT will
enable us to directly measure electron pairs from the 𝑐𝑐̅/𝑏𝑏̅ which is the main
background to measure the QGP thermal radiation at the intermediate mass region (1.2 <
mee < 2.9 GeV/c2), which will be our next focus of study.
14
2.8.
Budget Requests
The total budget request from this supplementary proposal for 3 years including Purdue
University indirect charges is $207,183.74
We request two students in this proposal. The University will cost share one graduate
student throughout the three-year duration of this project. The requested funding is
planned to cover the following costs in 3 years:
 Salaries and wages of one of the two requested students.
 Travel cost for the two requested students
 Computer purchase for the two requested students.
Salary & Graduate fee remissions: $105,289.89
The cost for one student for 3 years including salary, Graduate fee remissions and
employee benefits is $105,289.89
Travel: $36K
 The two students are expected to attend STAR collaboration meeting and analysis
meeting. These meetings discuss details of the data analysis and STAR collaboration
issues and are very beneficial to students. There are usually two collaboration
meetings and two analysis meetings each year. Each trip will cost $1000. Each
student will attend two of these meetings each year. In 3 years, the total cost for the
two students is $1000 X 2 trips X 2 students X 3 year = $12 K
 Each student will take one shift during RHIC option each year. Each trip will cost
$1000. In 3 years, the total cost is $1000 X 2 students X 3 year = $6 K.
 Starting from the second year, each student is expected to attend one domestic
workshop every year. Each trip will cost $2000. So the total cost is $2000 X 2
students X 2 year = $8 K.
 Each student is expected to attend one Quark Matter International conference during
the 3 years. Each trip will cost $5000 including the collaboration meeting right before
the conference. The total cost is $5000 X 2 = $10 K.
The total travel request in the 3 years is $36K including $26K for domestic and $10K for
international travel.
Equipment: $4K
Each student need one computer which costs $2000. The total cost is $2000 X 2 students
= $4K.
University indirect costs: $61,893.85
15
3. CURRENT SUPPORT
The current support is used to support two students to study heavy quark production at
RHIC.
The title of the support is
“THE EXPERIMENTAL STUDY OF THE PHASE STRUCTURE OF HADRONIC
MATTER”
January 1, 2009 – December 31, 2011
Department Of Energy (DOE), Grant: DE-FG02-88ER40412
PI: Rolf Scharenberg, Co-PI’s: Andrew Hirsch, Fuqiang Wang, Wei Xie
4. EXISTING RESOURCES
The proposed analysis will be carried on mainly in the RHIC Computing Facilities.
The Purdue PC farm will also be used. Our share of the farm consists of 8 dual-CPU
nodes (total of 16 CPUs) and disk storage of about 2 TB. Each dual-CPU node consists of
Dual 1.5 GHz Athlon processors, 1 GB of memory, Gigabit Ethernet, a 20 GB local hard
disk, and a 73 GB SCSI hard disk which is integrated in RAID for large-scale disk
storage. The storage space is mainly provided by two SnapAppliance Guardian 4400
NAS Servers which serve as a cross-mounted storage device. The PC-farm is supported
by the IT group funded by the Physics Department .
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5. BIOGRAPHICAL SKETCHS
Name

Wei Xie, Assistant Professor of Physics Department, Purdue University, West
Lafayette.
Education
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B.S., Physics 1991, Shangdong University, Jinan, Shandong, P.R. China
M.S., High Energy Physics 1994, Shangdong University, Jinan, Shandong, P.R.
China
Ph.D., High Energy Physics 1997, Institute of High Energy Physics, Academia
Sinica, Beijing, P.R. China
Professional Experience


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
Assistant Professor, Purdue University Dept. of Physics (2007-Present)
Riken-BNL Fellow, Riken-BNL Research Center, BNL (2004-2007)
Assistant Physicist, UC Riverside (2004-2004)
Postdoctoral Research Fellow, UC Riverside (2000-2004)
Postdoctoral Research Fellow, Weizmann Institute of Science, Israel (1997-2000)
Professional Activities

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

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

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Chairperson of the International Workshop on Heavy Quark Production in Heavy-ion
Collisions, West Lafayette, IN, 01/04-01/06, 2011.
Member of STAR Decadal Plan Committee. (2010-present).
Member of RHIC/AGS users Executive Committee (2010-present).
Member of STAR taskforce on non-photonic electron measurements (2009-present).
Committee member of Brookhaven National Lab review on the NSF funded PHENIX
muon trigger upgrade project (Oct. 2008).
Session chair of Heavy Quark Workshop at LBNL (Nov. 2007).
Member of STAR Heavy Flavor Silicon Detector Upgrade Project (2007-present)
Project Manager of PHENIX Reaction Plane Detector (2005-2007)
Co-convener of Heavy/Light Physics Working Group in PHENIX collaboration at
RHIC (2004-2007)
NSF grant Senior Collaborator of PHENIX forward upgrade project (2004-2007)
Co-organizer, Workshop on Heavy Flavor probes in studying the Hot/dense matter
created at RHIC , Brookhaven National Lab (2005)
Member, STAR Collaboration at RHIC(2007-present)
Member, PHENIX Collaboration at RHIC(1997-2007)
Member, CERES Collaboration at CERN(1997-present)
Member, American Physical Society (2000-present)
17
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Member, Mt. Kanbala and Yang-ba-jing cosmic-ray experiment in Tibet, China
(1991-1997)
Awards and Honors

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Co-PI of the Grant: DE-FG02-88ER40412 “THE EXPERIMENTAL STUDY OF
THE PHASE STRUCTURE OF STRONGLY INTERACTING MATTER”
submitted on October 2009, Proposal Period: January 1, 2009 – December 31, 2011
RIKEN/BNL Research Center Fellowship at Brookhaven National Lab (2004-2007)
Feinberg Fellowship at Weizmann Institute of Science, Israel (1997-2000)
Guang Hua Fellowship Award for outstanding undergraduate students in Shandong
University, P.R. China (1988)
Selected Publications in the Past Three Years
1. “Measurement of the Bottom contribution to non-photonic electron production in
$p+p$ collisions at $\sqrt{s} $=200 GeV.”, M.M. Aggarwal et al. (STAR
Collaboration) arXiv:1007.1200.
2. “$\Upsilon$ cross section in $p+p$ collisions at $\sqrt(s) = 200$ GeV”, M.M.
Aggarwal et al. (STAR Collaboration) , Phys. Rev. D 82, 012004 (2010).
3. “Balance Functions from Au$+$Au, $d+$Au, and $p+p$ Collisions at
$\sqrt{s_{NN}}$ = 200 GeV.”, M.M. Aggarwal et al. (STAR Collaboration)
Phys.Rev.C82, 024905 (2010).
4. “Azimuthal Charged-Particle Correlations and Possible Local Strong Parity
Violation”, B.I. Abelev et al. (STAR Collaboration) , Phys. Rev. Lett. 103, 251601
(2009).
5. “Long range rapidity correlations and jet production in high energy nuclear
collisions.”, B.I. Abelev et al. (STAR Collaboration) , Phys. Rev. C 80, 064912
(2009).
6. “Measurement of D* Mesons in Jets from p+p Collisions at s**(1/2) = 200-GeV”
B.I. Abelev et al. (STAR Collaboration) , Phys. Rev. D 79, 112006 (2009).
7. “Observation of Two-source Interference in the Photoproduction Reaction Au Au
Au Au + rho0”, B.I. Abelev et al. (STAR Collaboration), Phys. Rev. Lett. 102,
112301 (2009).
8. “Charged hadron multiplicity fluctuations in Au+Au and Cu+Cu collisions from
sqrt(s_NN) = 22.5 to 200 GeV”, A. Adare et al. Phys. Rev. C 78, 044902 (2008).
18
6. STUDENTS
Student
Date Entered
Grad. School
Date Joined
Group
Degree
Program
Date Degree
Awarded /
(Expected)
Advisor
Xin Li
M. Mustafa
Aug. 2006
Aug. 2009
Aug. 2007
Jun. 2010
Ph.D
Ph.D
Aug. 2012
Jun. 2014
Wei Xie
Wei Xie
Both Xin Li and M. Mustafa are studying heavy quark production at RHIC and are
supported by our existing DOE Grant: DE-FG02-88ER40412.
8. LIST OF TALKS AND PUBLICATIONS
8.1. Invited Talks in the Conference and Workshops in the past three years
1. “Measurement of Non-photonic Electron Production at RHIC”, invited seminar in
Ohio State University, Physics Department, Columbus, OH, June 3rd, 2010
2. “STAR open Heavy Flavor Measurements”, invited talk at XVIII International
Workshop on Deep- Inelastic Scattering and Related Subjects, April 2010. Florence,
Italy
3. “Taskforce report on non-photonic electron issue”, invited talk at the STAR
collaboration meeting plenary session, March 2010, Brookhaven national lab
4. “STAR heavy flavor measurements”, invited talk at the Strong interaction in the 21st
century, Feb. 2010, Mumbai, India.
5. “non-photonic electron in p+p”, invited talk at the STAR Workshop on Nonphotonic electron, May 2009, UCLA, LA
6. “B meson measurement using HFT silicon vertex detector”, invited talk at the HFT
project collaboration meeting at LBNL, Sep 2008.
19
8.2. List of Publications in Referred Journal in the Past Three Years
20
21
22
23
24
25
26
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