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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 with Fixed Target at RHIC

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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 Presentation

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Page 1: Drell-Yan with Fixed Target at RHIC

Drell-Yan with Fixed Targetat RHIC

“RHIC Spin: The Next Decade”at Iowa State University

May 15th, 2010Yuji Goto (RIKEN/RBRC)

Page 2: Drell-Yan with Fixed Target at RHIC

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

Page 3: Drell-Yan with Fixed Target at RHIC

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

Page 4: Drell-Yan with Fixed Target at RHIC

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

Page 5: Drell-Yan with Fixed Target at RHIC

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

Page 6: Drell-Yan with Fixed Target at RHIC

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

Page 7: Drell-Yan with Fixed Target at RHIC

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

Page 8: Drell-Yan with Fixed Target at RHIC

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

Page 9: Drell-Yan with Fixed Target at RHIC

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

Page 10: Drell-Yan with Fixed Target at RHIC

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

Page 11: Drell-Yan with Fixed Target at RHIC

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

Page 12: Drell-Yan with Fixed Target at RHIC

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

Page 13: Drell-Yan with Fixed Target at RHIC

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

Page 14: Drell-Yan with Fixed Target at RHIC

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

Page 15: Drell-Yan with Fixed Target at RHIC

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

Page 16: Drell-Yan with Fixed Target at RHIC

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

Page 17: Drell-Yan with Fixed Target at RHIC

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

Page 18: Drell-Yan with Fixed Target at RHIC

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

Page 19: Drell-Yan with Fixed Target at RHIC

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

Page 20: Drell-Yan with Fixed Target at RHIC

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

Page 21: Drell-Yan with Fixed Target at RHIC

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

Page 22: Drell-Yan with Fixed Target at RHIC

Backup slides

Page 23: Drell-Yan with Fixed Target at RHIC

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

Page 24: Drell-Yan with Fixed Target at RHIC

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

Page 25: Drell-Yan with Fixed Target at RHIC

Single transverse-spin asymmetry• Sivers function measurement• Transversity Boer-Mulders function measurement

by Stefano Melis

May 15, 2010 25

Page 26: Drell-Yan with Fixed Target at RHIC

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

Page 27: Drell-Yan with Fixed Target at RHIC

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

Page 28: Drell-Yan with Fixed Target at RHIC

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

Page 29: Drell-Yan with Fixed Target at RHIC

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

Page 30: Drell-Yan with Fixed Target at RHIC

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

Page 31: Drell-Yan with Fixed Target at RHIC

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

Page 32: Drell-Yan with Fixed Target at RHIC

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

Page 33: Drell-Yan with Fixed Target at RHIC

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

Page 34: Drell-Yan with Fixed Target at RHIC

FNAL-E906 First Magnet (FMag)

May 15, 2010 34

Page 35: Drell-Yan with Fixed Target at RHIC

FNAL-E906 First Magnet (FMag)

May 15, 2010 35

Page 36: Drell-Yan with Fixed Target at RHIC

FNAL-E906 Second Magnet (KMag)

May 15, 2010 36

Page 37: Drell-Yan with Fixed Target at RHIC

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

Page 38: Drell-Yan with Fixed Target at RHIC

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