1

FIRST THOUGHTS ABOUT EP/EA COLLISIONS AT PHENIX

E.C. Aschenauer PheniX & STAR meet EIC

E.C. Aschenauer PheniX & STAR meet EIC 2

Physics Topics unpolarised and polarised inclusive physics

detect only the scattered lepton F2 and FL for proton and nuclei, g1 and g2 for proton / He-3

d2σ empNC

dxdQ2 =2pαem2 Y+

xQ4 (F2 −y2Y+

FL±Y−Y+

xF3)

q(x, Q2 )+ q(x,Q2 ) g(x,Q2 ) q(x, Q2 )−q(x,Q2 )

antishadowing“sweet” spotR=1

shadowingLHC h=0RHIC h=3

Assumptions: 10GeV x 100GeV/n

√s=63GeV Ldt = 4/A fb-1

equiv to 3.8 1033 cm-2s-1

T=4weeks; DC:50% Detector: 100% efficient

Q2 up to kin. limit sx Statistical errors only

Note: L~1/A smearing effects can be significant

E.C. Aschenauer PheniX & STAR meet EIC 3

Physics Topics unpolarised and polarised inclusive physics

detect only the scattered lepton F2 and FL for proton and nuclei, g1 and g2 for proton / He-3

d2σ empNC

dxdQ2 =2pαem2 Y+

xQ4 (F2 −y2Y+

FL±Y−Y+

xF3)

q(x, Q2 )+ q(x,Q2 ) g(x,Q2 ) q(x, Q2 )−q(x,Q2 )

Lets get a feeling for systematic uncertainties: 1% energy-to-energy normalization low detector smearing will be crucial

tracking vs. calorimetry 1 - 2% vs. 5 - 10%

FL for fixed electron energy (4GeV)and proton energies:50, 70, 100, 250 GeVLuminosity: 4fb-1 each setting

E.C. Aschenauer PheniX & STAR meet EIC 4

Physics Topics unpolarised and polarised inclusive physics

detect only the scattered lepton F2 and FL for proton and nuclei, g1 and g2 for proton / He-3

d 2σ

dΩdE '~LmνΩ

mν

W mν =−gmνF1 −

pm pν

νF2 +

iνe mνλσqλσσ g1 +

iν 2

e mνλσqλ (p⋅qσσ −σ⋅qpσ )g2

Integrated Lumi: 5fb-

1

Same issues with detectorresolution as F2 and FLin addition need to reduce systematics due to polarisation

E.C. Aschenauer PheniX & STAR meet EIC 5

Kinematics

x

Q2

E.C. Aschenauer PheniX & STAR meet EIC 6

e’ Kinematics Lets concentrate on 4GeV lepton energy

electron beam “replaces” yellow hadron beamProton Energy

50 GeV 100 GeV 250 GeV

4x50

pe: 0-1 GeV pe: 1-2 GeV pe: 2-3 GeV pe: 3-4 GeV

e-p/A

180o 0o

E.C. Aschenauer PheniX & STAR meet EIC 7

Hadron Kinematics

4x100

4x250

4x250

4x1004x50

4x50

E.C. Aschenauer PheniX & STAR meet EIC 8

Diffractive Physics: p’ kinematics

4 x 100

t=(p4-p2)2 = 2[(mpin.mpout)-(EinEout - pzinpzout)]

4 x 50

4 x 50

4 x 250

?

Diffraction:

9E.C. Aschenauer PheniX & STAR meet EIC

Current PHENIX Detector at RHICMPC 3.1 < | h | < 3.9 2.5o < Q < 5.2o Muon Arms 1.2 < | h | < 2.4 South: 12o < Q < 37o

North: 10o < Q < 37o

Central Arms | h | < 0.35 60o < Q < 110o

e-

electrons will not make it to the south muon arm to much material

E.C. Aschenauer PheniX & STAR meet EIC 10

What will the current PheniX see4x

100

pe: 0-1 GeV pe: 1-2 GeV pe: 2-3 GeV pe: 3-4 GeV

4x100 4x100

Current PheniX detector not really useable for

DISacceptance not matched to DIS kinematics

E.C. Aschenauer PheniX & STAR meet EIC 11

HCALEMCAL

Preshower

How should a ePheniX look like Coverage in |h| =< 3 0.1 < Q2 < 100 (5o – 175o)

need an open geometry detector planes for next decadal plan

replace current central detector with a new one covering |h| =< 1 replace South muon arm by a endcap spectrometer able to do DY at |h| > 2.5, preferable 3 < |h| < 4

40cm

2T SolenoidEMCAL

HCAL

IPSilicon TrackerVTX + 1 layer

Silicon TrackerFVTX

1.2 < h < 2.7 8o < q < 37o

North Muon Arm

at least 1.5m

could be ILC-type HCAL with m-ID

might need a RICHfor HI physics or PID

5o @ 2m 17.4 cm dy

E.C. Aschenauer PheniX & STAR meet EIC 12

Questions which need answers is inclusive physics all we want to do? do we want to run through at all stages of eRHIC from

4x250 to 20x250 measuring luminosity for ep/eA symmetric vs. asymmetric collisions

for ep/eA collisions the IP would be much better not in the center of the detector but shifted to negative z

Problem silicon detectors: massive support material in the acceptance

material budget in the RHIC detectors momentum resolution critical for precision inclusive physics material and size of beam pipe