drell-yan with fixed target at rhic
DESCRIPTION
Drell-Yan with Fixed Target at RHIC. “RHIC Spin: The Next Decade” at Iowa State University May 15 th , 2010 Yuji Goto (RIKEN/RBRC). Drell-Yan experiment. The simplest process in hadron-hadron reactions No QCD final state effect Fermilab E866 Flavor asymmetry of sea-quark distribution. - PowerPoint PPT PresentationTRANSCRIPT
Drell-Yan with Fixed Targetat RHIC
“RHIC Spin: The Next Decade”at Iowa State University
May 15th, 2010Yuji Goto (RIKEN/RBRC)
Drell-Yan experiment• The simplest process in hadron-
hadron reactions
– No QCD final state effect
• Fermilab E866– Flavor asymmetry of sea-quark
distribution
DIS Drell-Yan
)(
)(1
2
1~
2 2
2
xu
xdpp
pd
012.0118.0)]()([
011.00803.0)]()([
CTEQ5Mwith
1
0
35.0
015.0
xuxddx
xuxddx
May 15, 2010 2
Drell-Yan experiment• Flavor asymmetry of sea-quark distribution
– Possible origins• meson-cloud model
– virtual meson-baryon state• chiral quark model• instanton model• chiral quark soliton model
– + in the proton as an origin of anti-d quark• pseudo-scaler meson should have orbital angular momentum in
the proton…
• Polarized Drell-Yan experiment– Not yet done!– Many new inputs for remaining proton-spin puzzle
• flavor asymmetry of the sea-quark polarization• transversity distribution• transverse-momentum dependent (TMD) distributions
– Sivers function, Boer-Mulders function, etc.
, , npp
May 15, 2010 3
Single transverse-spin asymmetry• Sivers effect
– Correlation between nucleon transverse spin and parton transverse momentum (Sivers distribution function)
– Related to the orbital angular momentum in the proton (and the shape of the proton)
• Multi-dimensional structure of the proton
– Initial-state or final-state interaction with remnant partons
Anselmino, et al., PRD79, 054010 (2009)
J-PARC50-GeVpolarized beams ~ 10 GeV
RHICcolliders = 200 GeV
May 15, 2010 4
Sivers function measurement• Sign of Sivers function determined by single transverse-spin
(SSA) measurement of DIS and Drell-Yan processes– Should be opposite each other
• Initial-state interaction or final-state interaction with remnant partons
• < 1% level multi-points measurements have already been done for SSA of DIS process– x = 0.005 – 0.3 (more sensitive in lower-x region)
• comparable level measurement needs to be done for SSA of Drell-Yan process for comparison
May 15, 2010 5
J-PARC and/or RHIC• J-PARC
– Advantage• High intensity = high luminosity
– Disadvantage• Smaller cross section (at the same invariant mass)
– Uncertainties• Availability of 50 GeV beam• Polarized proton beam?
• RHIC– Advantage
• Polarized proton beam available• Larger cross section (at the same invariant mass)
– Disadvantage• Luminosity?
– Collider or fixed-target (internal-target) experiment
May 15, 2010 6
FNAL-E906 dimuon spectrometer
25m
Solid IronSolid Iron Focusing
Magnet, Hadron
absorber and beam
dump
4.9m
Mom. Meas.
(KTeV Magnet)
Ha
dro
n A
bso
rbe
r
Station 1:
Hodoscope array
MWPC tracking
Station 2 and 3:
Hodoscope array
Drift Chamber tracking
Station 4:
Hodoscope array
Prop tube tracking
Liquid H2, d2, and solid targets
May 15, 2010 7
PYTHIA simulation with IP2 configuration• IP2 configuration shown in the next slide
– detector components from FNAL-E906 apparatus• E906: total z-length ~25 m• IP2: available z-lengh ~14 m
– z-length of FMAG (1st magnet) is shortened• because of limited z-length at IP2
• PYTHIA simulation– s = 22 GeV (Elab = 250 GeV)– luminosity assumption 10,000 pb-1
• 10 times larger luminosity necessary than collider experiments• because of ~10 times smaller cross section acceptance (in the same
mass region)– M = 4.5 8 GeV– acceptance for Drell-Yan dimuon signal is studied– momentum resolution (geometric) 6 10-4 p (GeV/c)– background rate needs to be studied
May 15, 2010 8
Internal target position
IP2 (overplotted on BRAHMS)
DXDOQ1
DX
20 TON
CRANE LIMIT
20 TON
CRANE LIMITCRANE LIMIT
20 TON
CRANE LIMIT
20 TON
POWER PANELS
C
SCALE
0 5' 10'
CRYOGENIC PIPINGCRYOGENIC PIPING
DO Q1 Q2 Q3DO
1EF3
1EF4
2XAV12XAV2
2XEF1
C.O.D.P .
6 each Blocks
3'W X 4'-6 "H X 4'L
3/ 8Ty p
3/ 8Ty p
3/ 8Ty p
3/ 8Ty p
36X80 Man D oorKeyed B B11 &
Card R eader Ac cess
48 X 54 F resh AirInl et G ravity D amper
Q03 Q02 Q01 D0 DXIP
Q03 Q02 Q01 D0 DXIP
36X80 Man D oor
Keyed B B11 &
Card R eader Ac cess
48 X 54 F resh Air
Inl et G ravity D amper
FMAG 3.9 mMom.kick2.1 GeV/c
KMAG 2.4 mMom.kick0.55 GeV/c
St.4MuID
14 m18 m
St.1St.2 St.3
May 15, 2010 9
all generated dumuonfrom Drell-Yan
passed through FMAG
passed through St. 1
passed through St. 2
passed through St. 3
accepted by all detectors
Drell-Yan at IP2
rapidity E1 vs E2 (accepted events)
E1, E2: energy of dimuonsenergy cut shown ~10 GeV
May 15, 2010 10
Drell-Yan at IP2
accepted4.5 - 8 GeV/c2
4.5 - 5 GeV/c2
5 - 6 GeV/c2
6 - 8 GeV/c2
rapidity
x1
xF
pT
May 15, 2010 11
Drell-Yan at IP2• About 50,000 events
for 10,000 pb-1
• x1 vs x2 (accepted events)– x1: x of beam proton
(polarized)– x2: x of target proton
Mass(GeV/c2) Total
Rapidity 45 – 50 50 – 60 60 – 80 45 – 80
-0.4 – 0 3.1 K 3.1 K 1.4 K 7.6 K
0 – 0.4 6.2 K 6.1 K 3.0 K 15.3 K
0.4 – 0.8 7.6 K 6.4 K 2.3 K 16.3 K
0.8 – 1.2 4.4 K 2.5 K 0.4 K 7.3 K
May 15, 2010 12
Collider vs fixed-target• x1 & x2 coverage
– Collider experiment with PHENIX muon arm (simple PYTHIA simulation)• s = 500 GeV• Angle & E cut only
– 1.2 < || < 2.2 (0.22 < || < 0.59), E > 2, 5, 10 GeV– (no magnetic field, no detector acceptance)
• luminosity assumption 1,000 pb-1
• M = 4.5 8 GeV• Single arm: x1 = 0.05 – 0.1 (x2 = 0.001 – 0.002)
– Very sensitive x-region of SIDIS data– Fixed-target experiment
• x1 = 0.25 – 0.4 (x2 = 0.1 – 0.2)– Can explore higher-x region with better sensitivity
PHENIX muon arm (angle & E cut only)
x1
x2 x2
x1
Fixed-target experiment
May 15, 2010 13
Fixed-target experiment• Phase-1: parasitic experiment (with other collider
experiments)– Beam intensity 2×1011×10MHz = 21018/sec– Cluster or pellet target 1015/cm2
• 50 times thinner than RHIC CNI carbon target
– Luminosity 2×1033/cm2/sec– 10,000pb-1 with 5×106sec
• 8 weeks, or 3 years (10 weeks×3) with efficiency and live time
– Reaction rate 2×1033×50mb = 108/sec = 100MHz– Beam lifetime 2×1011×100bunch / 108 = 2×105sec (at
longest)• More factor to make the lifetime shorter, but expected to be still
long enough
May 15, 2010 14
Fixed-target experiment• Phase-2: dedicated experiment
– Beam intensity 2×1011×30MHz = 6×1018/sec– Cluster, pellet or solid target 1016/cm2
• 5 times thinner than RHIC CNI carbon target– Luminosity 6×1034/cm2/sec– 10,000pb-1 with 2×105sec
• 3 days, or 2 weeks with efficiency and live time– Or 50,000pb-1 with 106sec
• 2 weeks, or 8 weeks with efficiency and live time– Reaction rate 6×1034×50mb = 3×109/sec = 3GHz– Beam lifetime 2×1011×300bunch / 3×109 = 2×104sec ~
6hours• More factor to make the lifetime shorter• Special short-interval operation necessary
May 15, 2010 15
Physics• Experimental sensitivity
– Phase-1 (parasitic operation)• L = 2×1033 cm-2s-1
• 10,000 pb-1 with 5106 s ~ 8 weeks (1 year), or 3 years of beam time by considering efficiency and live time
– Phase-2 (dedicated operation)• L = 6×1034 cm-2s-1
• 50,000 pb-1 with 106 s ~ 2 weeks, or 8 weeks (1 year) of beam time by considering efficiency and live time
10,000 pb-1 (phase-1)50,000 pb-1 (phase-2)
Theory calculation:U. D’Alesio and S. Melis, private communication;M. Anselmino, et al., Phys. Rev. D79, 054010 (2009)
May 15, 2010 16
pQCD studies of Drell-Yan cross section• pQCD correction can be controlled
NNLO calculationHamberg, van Neerven, Matsuura,Harlander, Kilgore
NLL, NNLL calculationYokoya, et al...
by Hiroshi Yokoya
May 15, 2010 17
Letter of Intent• Author list
– ANL• D. F. Geesaman, R. E. Reimer, J. Rubin
– UIUC• M. Grosse Perdekamp, J.-C. Peng
– KEK• N. Saito, S. Sawada
– LANL• M. Brooks, X. Jiang, G. Kunde, M. J. Leitch, M. X. Liu, P. L. McGaughey
– RIKEN• Y. Fukao, Y. Goto, I. Nakagawa, R. Seidl, A. Taketani
– RBRC• K. Okada
– Stony Brook Univ.• A. Deshpande
– Tokyo Tech• K. Nakano, T.-A. Shibata
– Yamagata Univ.• N. Doshita, T. Iwata, K. Kondo, Y. Miyachi
May 15, 2010 18
Fixed-target experiment• Internal target
– Storage cell target (polarized)• H2, D2, 3He
• 1014 / cm2
• HERMES
– Cluster jet target• H2, D2, N2, CH4, Ne, Ar, Kr, Xe, …
• 1014 – 1015 / cm2
• CELSIUS (Uppsala), FNAL-E835, Muenster, COSY, GSI, …
– Pellet target• H2, D2, N2, Ne, Ar, Kr, Xe, …
• 1015 – 1016 / cm2
• CELSIUS (Uppsala), COSY, GSI, …
Double-spin experiment possibleLow density = low luminosityIssue to be used in the RHIC ring
High luminosityOnly single-spin experiment possible
May 15, 2010 19
Cost and schedule• To be considered…• Cost
– Accelerator & experimental hall (IP2)• the most expensive part?
– Internal target• e.g. PANDA pellet target: $1.5M R&D, infrastructure + $1.5M
construction– Experimental apparatus
• FNAL-E906 magnet (modification) or other existing magnet at BNL• FNAL-E906 apparatus (modification) and/or new/existing apparatus
• Schedule– 2010-2013 FNAL-E906 beam time– 2011-13 accelerator R&D, internal target R&D + construction– 2014 experimental setup & commissioning at RHIC– 2015-2017 phase-1: parasitic experiment– 2018 phase-2: dedicated experiment
May 15, 2010 20
Issues (as a summary)• Requirement for target thickness
– In phase-1 (parasitic operation), 1015 /cm2 thickness is necessary to achieve L = 21033 cm-2s-1
• Pellet target (~1015 /cm2) or cluster-jet target (up to 81014/cm2 ?) is necessary
• If it is not achieved, the internal-target experiment would not be competitive against collider experiments
• In collider experiments, L = 2(or 3)1032 is expected and cross section ( acceptance) is >10 times larger
– In phase-2 (dedicated operation), 10-times larger thickness, 1016 /cm2 is expected
• Requirement for accelerator– Compensation of dipole magnets in the experimental apparatus
• both beams need to be restored on axis in two colliding-beam operation– Size of the experimental site and possible target-position (with proper
beam operation)– Reaction rate (peak rate) and beam lifetime– Radiation issues
• Beam loss/dump requirement
May 15, 2010 21
Backup slides
Polarized Drell-Yan experiment• Single transverse-spin asymmetry
– Sivers function measurement– Transversity Boer-Mulders function
• Double transverse-spin asymmetry– Transversity (quark antiquark for p+p collisions)
• Double helicity asymmtry– Flavor asymmetry of quark polarization
• Other physics– Parity violation asymmetry?
May 15, 2010 23
DIS Drell-Yan
“toy” QED
QCD
attractive repulsive
Sivers function measurement• Sign of Sivers function determined by single transverse-spin
(SSA) measurement of DIS and Drell-Yan processes– Should be opposite each other
• Initial-state interaction or final-state interaction with remnant partons– Test of TMD factorization– Explanation by Vogelsang and Yuan…
• From “Transverse-Spin Drell-Yan Physics at RHIC,” Les Bland, et al., May 1, 2007
May 15, 2010 24
Single transverse-spin asymmetry• Sivers function measurement• Transversity Boer-Mulders function measurement
by Stefano Melis
May 15, 2010 25
Polarized and unpolarized Drell-Yan experiment • ATT measurement
– h1(x): transversity• quark antiquark in p+p
collisions
• Unpolarized measurement– angular distribution of
unpolarized Drell-Yan– Boer-Mulders function
• violation of the Lam-Tung relation
2
2
21112
21112
cos1
)2cos(sinˆ
))21()()((
))21()()((
ˆ
21
SSTT
qqqq
qqqq
TTTT
a
xfxfe
xhxhe
aA
2 21 31 cos sin 2 cos sin cos 2
4 2
d
d
,
L.Y. Zhu,J.C. Peng, P. Reimer et al.hep-ex/0609005
With Boer-Mulders function h1┴:
ν(π-Wµ+µ-X)~valence h1┴(π)*valence h1
┴(p)
ν(pdµ+µ-X)~valence h1┴(p)*sea h1
┴(p)
May 15, 2010 26
Polarized Drell-Yan experiment • Longitudinally-polarized measurement
– ALL measurement
– flavor asymmetry of sea-quark polarization• SIDIS data from HERMES, and new COMPASS data available• W data from RHIC will be available in the near future• Polarized Drell-Yan data will be able to cover higher-x region
Bhalerao, statistical modelCao & Signa, bag modelCao & Signa, meson cloudWakamatsu, CQSM SU(2)Wakamatsu, CQSM SU(3)
HERMES, PRD71: 012003, 2005
)( dux
May 15, 2010 27
FNAL-E906 dimuon spectrometer
Solid iron magnet§ Reuse SM3 magnet coils§ Sufficient Field with reasonable coils
(amp-turns)§ Beam dumped within magnet
25m
Solid IronSolid Iron
Focusing Magnet,
Hadron absorber
and beam dump
4.9m
Mom. Meas.
(KTeV Magnet)
Had
ron
Abs
orbe
r
Station 1:
Hodoscope array
MWPC tracking
Station 2 and 3:
Hodoscope array
Drift Chamber tracking
Station 4:
Hodoscope array
Prop tube tracking
Liquid H2, d2, and solid targets
May 15, 2010 28
pQCD studies of Drell-Yan cross section• pQCD correction can be controlled at J-PARC energy
NNLO calculationHamberg, van Neerven, Matsuura,Harlander, Kilgore
NLL, NNLL calculationYokoya, et al...
by Hiroshi Yokoya
May 15, 2010 29
Collider experiment• Very simple PYTHIA simulation for
PHENIX muon arm– s = 500 GeV– Angle & E cut only
• 1.2 < || < 2.2 (0.22 < || < 0.59)• E > 2, 5, 10 GeV• (no magnetic field, no detector acceptance)
– RHIC-II luminosity assumption 1,000 pb-1
– M = 4.5 8 GeV
rapidity #event- 2.4, - 2.0 5K-2.0, - 1.6 28K-1.6, - 1.2 17K-0.4, 0.0 3K0.0, 0.4 3K1.2, 1.6 18K1.6, 2.0 31K2.0, 2.4 5K
110K events total with 2-GeV cut
May 15, 2010 30
Collider experiment• “Transverse-Spin Drell-Yan
Physics at RHIC”– Les Bland, et al., May 1, 2007– s = 200 GeV– PHENIX muon arm– STAR FMS (Forward Muon
Spectrometer)– Large background from b-
quark– s = 500 GeV may be better…
• Higher luminosity and larger cross section
May 15, 2010 31
Collider experiment• Very simple PYTHIA simulation for a dedicated
collider experiment– s = 500 GeV– Angle & E cut only
• || < 2.2• E > 2, 5, 10 GeV• (no magnetic field, no detector acceptance)
– RHIC-II luminosity assumption 1,000 pb-1
– M = 4.5 8 GeV rapidity #event- 2.4, - 2.0 5K-2.0, - 1.6 32K-1.6, - 1.2 53K-1.2, - 0.8 53K-0.8, - 0.4 60K-0.4, 0.0 70K0.0, 0.4 68K0.4, 0.8 60K0.8, 1.2 55K1.2, 1.6 54K1.6, 2.0 36K2.0, 2.4 5K
550K events totalwith 2-GeV cut
May 15, 2010 32
Fixed-target experiment• Simple PYTHIA simulation for a fixed target experiement
– s = 22 GeV (Elab = 250 GeV)– Angle & E cut only
• 0.03 < < 0.1• E > 2, 5, 10 GeV• (no magnetic field, no detector acceptance)
– luminosity assumption 10,000 pb-1
• 10 times larger luminosity necessary than collider experiments• because of ~10 times smaller cross section acceptance
– M = 4.5 8 GeV
rapidity #event- 0.4, 0.0 1K0.0, 0.4 17K0.4, 0.8 14K0.8, 1.2 2K
35K events total with 10-GeV cut Red: E > 2 GeV cut Green: E > 5 GeV cut Blue: E > 10 GeV cut
May 15, 2010 33
FNAL-E906 First Magnet (FMag)
May 15, 2010 34
FNAL-E906 First Magnet (FMag)
May 15, 2010 35
FNAL-E906 Second Magnet (KMag)
May 15, 2010 36
experiment particles energy x1 or x2 luminosity
COMPASS + p 160 GeVs = 17.4 GeV
x2 = 0.2 – 0.3 2 × 1033 cm-2s-1
COMPASS (low mass) + p 160 GeVs = 17.4 GeV
x2 ~ 0.05 2 × 1033 cm-2s-1
PAX p + pbar colliders = 14 GeV
x1 = 0.1 – 0.9 2 × 1030 cm-2s-1
PANDA(low mass)
pbar + p 15 GeVs = 5.5 GeV
x2 = 0.2 – 0.4 2 × 1032 cm-2s-1
J-PARC p + p 50 GeVs = 10 GeV
x1 = 0.5 – 0.9 1035 cm-2s-1
NICA p + p colliders = 20 GeV
x1 = 0.1 – 0.8 1030 cm-2s-1
SPASCHARM(low mass)
p + p 60 GeVs = 11 GeV
x2 = 0.05 – 0.2
SPASCHARM(low mass)
+ p 34 GeVs = 8 GeV
x2 = 0.1 – 0.3
RHIC PHENIXMuon
p + p colliders = 500 GeV
x1 = 0.05 – 0.1 2 × 1032 cm-2s-1
RHIC InternalTarget phase-1
p + p 250 GeVs = 22 GeV
x1 = 0.25 – 0.4 2 × 1033 cm-2s-1
RHIC InternalTarget phase-2
p + p 250 GeVs = 22 GeV
x1 = 0.25 – 0.4 6 × 1034 cm-2s-1
May 15, 2010 37
Accelerator issues• Experimental dipole magnets
– Beam axis restoration (one beam on target, the other beam displaced)
• Size of the experimental site and possible target-position (with proper beam operation)– IP2 (BRAHMS) area?
• Reaction rate (peak rate) and beam lifetime• Radiation issues
– Beam loss/dump requirement
May 15, 2010 38