Measurement of the -meson production in the RHI Collisions with
the PHENIX detector at RHIC Sasha Milov Weizmann Institute of
Science for the PHENIX Collaboration
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Part I. Analysis
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Sasha Milov, WISH-2010, Catania: "Measurement of ..."
Aug,10,2010 3 Data samples Year Speciess [GeV ] LdtN tot (sampled)
Run12000Au - Au1301 b -1 10 M Run22001/02 Au - Au20024 b -1 170 M
Au - Au19 < 1 M p - p2000.15 pb -1 3.7 B Run32002/03 d -
Au2002.74 nb -1 5.5 B p - p2000.35 pb -1 6.6 B Run42003/04 Au -
Au200241 b -1 1.5 B Au - Au62.49 b -1 58 M Run52005 Cu - Cu2003 nb
-1 8.6 B Cu - Cu62.40.19 nb -1 0.4 B Cu - Cu22.42.7 b -1 9 M p -
p2003.8 pb -1 85 B Run-62006 p - p20010.7 pb -1 233 B p - p62.40.1
pb -1 28 B Run-72007Au - Au200813 b -1 5.1 B Run-82007/08 d -
Au20080 nb -1 160 B p - p2005.2 pb -1 115 B Au - Au9.2 few k
Published: arXiv:1005.3674 arXiv:1004.3532 Phys. Rev. Lett. 99,
052301 (2007) Phys. Rev. C 72, 014903 (2005) Preliminary M. Naglis,
meson production in p+p, d+Au and Au+Au collisions at RHIC using
the PHENIX detector. PhD thesis, WIS, 2009. D. Sharma, - and -meson
production in p+p and d+Au collisions at RHIC energies, using the
PHENIX Detector. PhD thesis, WIS, 2010.
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Sasha Milov, WISH-2010, Catania: "Measurement of ..."
Aug,10,2010 4 K + K mode ToF-ToF configuration: Provides the
cleanest sample, but is limited both in acceptance an in momentum.
ToF-EMCToF configuration: This configuration was used only in run2
analysis because it is limited in p T of the particles. ToF-noPID
configuration: Provides larger acceptance on expense of worse S/B
ratio, but increases overall significance and momentum reach noPID+
matching: Allows cleaning the sample and make systematic studies
noPID-noPID configuration: Getting even larger acceptance Central
arm acceptance: | | < 0.35 = 2 x 90 o
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Sasha Milov, WISH-2010, Catania: "Measurement of ..."
Aug,10,2010 5 K + K mode K + K (two K ID) SystemN evt p T
(GeV/c)Method p+p1.44 10 9 1.3 7.0no PID 1.50 10 9 0.9 4.5one K PID
d+Au 63 10 6 1.45 5.1no PID Au+Au824 10 6 2.45 7.0no PID 722 10 6
1.1 3.95two K PID Peak examples are shown for p+p data at s=
200GeV
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Sasha Milov, WISH-2010, Catania: "Measurement of ..."
Aug,10,2010 6 e + e mode Central arm acceptance: | | < 0.35 = 2
x 90 o Tracking: Use of both arms and two arms decays to increase
statistics and low p T coverage. Electron Identification: RICH +
EMCal (both technologies) to increase coverage and reduce
systematic errors. Combinatorial Background Subtraction: Based on
mixing technique using pairs from different events. Events must be
similar in vertex and centrality. Dalitz pair rejection: Not yet
used, but will be possible with HBD data from runs 2009, 2010.
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Sasha Milov, WISH-2010, Catania: "Measurement of ..."
Aug,10,2010 7 Electron identification Purity Upper curve: all
tracks Middle curve: e + e identified by RICH Lower curve: Random
coincidence. E/p cut increases electron sample purity by additional
factor of 10. Upper curve: pairs from where only one track is
identified as e + or e coming from Dalitzes and conversions Middle
curve: pairs open up in the plane orthogonal to magnetic field
(remove Dalitzes) Lower curve: Pairs where the second track was not
identified as an electron. Efficiency Mass corresponding to the
beam-pipe radius RICH e/=1000 EMCal e/=10
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Pool of electrons from same event category: centrality,
reaction plane, vertex Sasha Milov, WISH-2010, Catania:
"Measurement of ..." Aug,10,2010 8 Combinatorial background Event
Ne Ne + ee e+e+ ee e+e+ ee e+e+ ee M e + e M e + e + M e e M e + e
+ M e e SubtractionNormalization 0 e + e e + e Combinatorial
Background Subtraction: PRC81, 034911 (2010) = 2
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Sasha Milov, WISH-2010, Catania: "Measurement of ..."
Aug,10,2010 9 e + e mode p+p Au+Au d+Au In p+p: Combinatorial
Background Subtraction was not used, because the S/B ration is
relatively high ~ 5:1. In d+Au: C.B.S. was used for MB trigger
only. For ERT the mixing was done for MB and ERT condition was
imposed on it. S/B varies from 10:1 to 1:10 (approx.) In Au+Au:
C.B.S. is the only way to estimate the signal. S/B ration is very
low < 1:100 Under the peaks: Correlated background. The
Cocktail
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Sasha Milov, WISH-2010, Catania: "Measurement of ..."
Aug,10,2010 10Efficiencies Acceptance: Includes geometry, inactive
regions, detector response, analysis cuts. Trigger efficiency to a
triggering (daughter) particle: Measured from MB sample, includes
trigger electronics inactive areas Trigger efficiency to the
analyzed (mother) particle: Deduced from the MC and the single
particle trigger efficiency.
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Sasha Milov, WISH-2010, Catania: "Measurement of ..."
Aug,10,2010 11 + mode Muon arm acceptances: -2.4< < -1.2
1.2< < 2.2 = 2 Sample : So far run8 (d+Au) p+p sample also
very promicing Muon arms: Use acceptance of both muon arms. CBS:
The sample is biased therefore use of CBS is difficult. We used
modified method of the CBS Clear signal form and / .
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Part IIa. Results (Spectral widths shapes and yields)
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Sasha Milov, WISH-2010, Catania: "Measurement of ..."
Aug,10,2010 13 Line shape modification Phys. Rev., C63 (2001)
054907 Chiral Symmetry Restoration probe: Due to its short
life-time (44 fm/c), the is considered a probe of the Chiral
Symmetry Restoration The line shaper and/or position of the
particle can be different from the vacuum value. The effect is
expected to be seen in: The most central AuAu collisions At low p
T. In di-lepton channel The data is measured in: The MB AuAu
collisions At average p T In hadronic channel I do not have results
on e + e in p+p But one does not expect large signal there
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Sasha Milov, WISH-2010, Catania: "Measurement of ..."
Aug,10,2010 14 p+p spectra @ 200 GeV Consistency: An agreement
between different K- ID methods was shown before K + K and e + e
results very well agree to each other Momentum coverage: e + e mode
allows measurement at zero p T, thus providing the integrated
yield. K + K mode w/o identification extends to 7 GeV/c, limited by
statistics. Self-consistent result in a wide p T range from 0.125
to 7 GeV/c
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Sasha Milov, WISH-2010, Catania: "Measurement of ..."
Aug,10,2010 15 Integrated Yields in p+p @ 200GeV dN/dy and : First
time direct counting of the integrated parameters, no
extrapolations or model assumptions PHENIX / STAR: The numbers are
close between the experiments, which is not always the case
Statistical model agreement: Not clear why the stat. model works in
p+p, but it does a good job. arXiv:1005.3674 Stat model calculation
from EPJC66, 377 (2010) dN/dy and of -meson are directly measured
in p+p
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Sasha Milov, WISH-2010, Catania: "Measurement of ..."
Aug,10,2010 16 A+A @ 200 GeV in K + K Spectra in A+A: Measured
above 1GeV/c in full range of centralities and systems. Fits well
to Tsallis function, and departs from exponential. High p T : The
departures depends on species and centralities. Consistent with
recombination models. Low p T : No significant change in slope.
Support an expectation of a lesser radial flow for - meson. PHENIX
provides full set of measurements @ 200 GeV in K + K
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Sasha Milov, WISH-2010, Catania: "Measurement of ..."
Aug,10,2010 17 d(Au)+Au @ 200 GeV in e + e d+Au: Covering the
entire p T range form zero to 6 GeV/c in all centrality bins.
Au+Au: The run4 Preliminary data which is of a lesser stat.
significance compare to hadronic channel. It will remain so before
the HBD results are analyzed. The lighter systems are measured. The
analysis of AuAu data required HBD samples to be analyzed.
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Sasha Milov, WISH-2010, Catania: "Measurement of ..."
Aug,10,2010 18 Integrated Yields in A(d)+A @200GeV Integrated
parameters: Due to p T range in K + K mode the integrated values
require assumptions to work them out In e + e the result suffers
from extremely poor statistics and shall be taken seriously only
with the systematic errors. The slope parameter: T changes very
little with increasing N part but clearly depends on s NN The yield
per participant: Clear increase from p+p to central AuAu in both
measured energies. @200GeV the increase is approximately by a
factor of 3 Yields increase with N part. Slopes remain the
same.
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Sasha Milov, WISH-2010, Catania: "Measurement of ..."
Aug,10,2010 19 Spectra @ 62GeV Spectra: PHENIX has Preliminary
results on -meson production measured in K + K decay channel at 62
GeV in p+p, CuCu and AuAu systems. Measurements are done above
1GeV/c and extends to 3-4GeV/c limited by available statistics. The
results exist in full range of centralities and systems. Full set
of data to study the systematics of the at lower energy.
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Part IIb. Not about physics
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Sasha Milov, WISH-2010, Catania: "Measurement of ..."
Aug,10,2010 22 A factor of 2. Integrated yield in p+p: Perhaps the
only measurement where PHENIX and STAR agree. Spectra in all
systems: Consistently show higher rates measured by STAR reaching a
factor of 2 for the same number of participants in Au+Au. Ratios:
Yet the ratios to p+p like R AA and dN/dy look more or less the
same. PHENIX takes it very seriously. With a variety of samples,
decay modes and techniques, we give the -meson a very special
treatment. We hope STAR does the same. Compiled by M.Naglis
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Part IIc. Results(Flow)
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Sasha Milov, WISH-2010, Catania: "Measurement of ..."
Aug,10,2010 24Flow Results: PHENIX published results of run4 and
has preliminary analysis of run7 flow of -meson in AuAu at 200 GeV.
The results are consistent. Scaling: Elliptic flow v 2 of the -
meson scales with the number of quarks the vs. kE T /q similar to
the scaling observed for all the measured particles. Flow of the is
crucial for establishing the validity of the flow scaling with the
number of quarks.
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Part IIc. Results (Nuclear Modification Factor)
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Sasha Milov, WISH-2010, Catania: "Measurement of ..."
Aug,10,2010 26 RdA @ 200 GeV Run3: Preliminary PHENIX results left
room for some increase of the RdA at high p T. Although the data
was also consistent with the flat behavior the trend was
suggestive. Run8: Final results published by PHENIX show no
increase. The new results extend to 7 GeV/c and above 1 GeV/c the
behavior of -meson is consistent with the trends shown by other
mesons. Cold Nuclear Matter effects in -meson production @ 200 GeV
are weak if any.
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Sasha Milov, WISH-2010, Catania: "Measurement of ..."
Aug,10,2010 27 RdA @ 200 GeV The result is new and promising, work
on it continues. Au d First look: is suppressed in d-going
direction, In Au-going direction the ration is constant like at
mid-rapidity (we are looking at rather high-p T )
Slide 28
Sasha Milov, WISH-2010, Catania: "Measurement of ..."
Aug,10,2010 28 Cu+Cu @ 200 & 62 GeV R AA in CuCu and AuAu shows
similar suppression for close N part The same behavior is measured
for all other particles in these systems
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Sasha Milov, WISH-2010, Catania: "Measurement of ..."
Aug,10,2010 29 Almost a summary At mid-rapidity, in all decay
modes, in all systems, at all energies, in all parameters we
measured: K + K , e + e p+p, d+Au, Cu+Cu, Au+Au 62 GeV, 200 GeV
RAA, flow the -meson behaves consistently with all other mesons in
the full p T range of our measurements. The values seems to show
different behavior are the integrated yields per participant,
significantly increasing from p+p to the most central Au+Au
events.
Slide 30 5GeV/c the R AA s are comparable at present
statistics. That however is in contradiction to the -meson trend
which has ~50% strange quark content and behaves similar to 0
Closer to central: The difference between the two particles grows
up at intermediate p T s. In the most peripheral: shows no
enhancement, however it is not suppressed by ~0.8 like 0 -meson
suppression is far from being understood. We need low and high p T
data and other s-quark particles to complete the picture.">
Sasha Milov, WISH-2010, Catania: "Measurement of ..."
Aug,10,2010 30 R AA @ 200 GeV In the most central: At pT 5GeV/c the
R AA s are comparable at present statistics. That however is in
contradiction to the -meson trend which has ~50% strange quark
content and behaves similar to 0 Closer to central: The difference
between the two particles grows up at intermediate p T s. In the
most peripheral: shows no enhancement, however it is not suppressed
by ~0.8 like 0 -meson suppression is far from being understood. We
need low and high p T data and other s-quark particles to complete
the picture.
Sasha Milov, WISH-2010, Catania: "Measurement of ..."
Aug,10,2010 36 HBD peaks
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Part I. Detector
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Sasha Milov, WISH-2010, Catania: "Measurement of ..."
Aug,10,2010 38 The PHENIX detector Pioneering High Energy Nuclear
Interaction eXperiment Magnetic Field: Outer coils: Bdl = 0.78 Tm
Polarity can change for systematic studies and field configuration
with Inner coil. Inner coil: + + mode Bdl = 1.04 Tm Increase in
tracking resolution + mode Bdl = 0.43 Tm Creating zero-field region
Central arm acceptance: | | < 0.35 = 2 x 90 o
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Sasha Milov, WISH-2010, Catania: "Measurement of ..."
Aug,10,2010 39 The PHENIX detector Pioneering High Energy Nuclear
Interaction eXperiment Global detectors: BBC / ZDC: trigger,
vertex, timing, centrality. trigger = 50% 92% vertex = 0.5cm 2cm
Tracking System: DC / PC1: momentum, pattern recognition. dp T /p T
1.0%p T + 0.7% Pattern recognition: DC / PC1 + PC2 + PC3/EMCal:
events structure, fake rejection occupancy = 100% 85% Calorimetry:
PbSc / PbGl: EM component, E /E 8.1%/E + 3.0% Central arm
acceptance: | | < 0.35 = 2 x 90 o
Slide 40 1000 Other (not used) RPC ToF Aerogel HBD Central arm
acceptance: | | < 0.35 = 2 x 90 o">
Sasha Milov, WISH-2010, Catania: "Measurement of ..."
Aug,10,2010 40 The PHENIX detector Pioneering High Energy Nuclear
Interaction eXperiment Time of Flight: Scintillating slabs: p/K
< 4.5 GeV/c /K < 2.5 GeV/c ToF 100 ps Calorimetry: PbSc: ToF
ToF 500 ps PbSc/PbGl: Shower shape, E/p eID: RICH PMT/CO 2 : e/
> 1000 Other (not used) RPC ToF Aerogel HBD Central arm
acceptance: | | < 0.35 = 2 x 90 o
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Sasha Milov, WISH-2010, Catania: "Measurement of ..."
Aug,10,2010 41 The PHENIX detector Pioneering High Energy Nuclear
Interaction eXperiment Triggers: Minimum Biased: 1 or more hits on
each side ERT gamma: 2x2(4x4) EMCal towers must exceed threshold
ERT electron: The same in coincidence with RICH hit Central arm
acceptance: | | < 0.35 = 2 x 90 o