1

FIRST THOUGHTS ABOUT EP/EA COLLISIONS AT PHENIX

EIC EW Meeting, W&M, VA, May 2010E.C. Aschenauer

EIC EW Meeting, W&M, VA, May 2010 2

Physics Topics

E.C. Aschenauer

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

d2σempNC

dxdQ2 =2παem2 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

EIC EW Meeting, W&M, VA, May 2010 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

d2σempNC

dxdQ2 =2παem2 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

EIC EW Meeting, W&M, VA, May 2010 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 2σdΩdE '

~LμνWμν

W μν =−gμνF1 −

pμ pν

νF2 +

iνε μνλσqλsσ g1 +

i

ν 2ε μνλσqλ (p⋅qsσ −s⋅qpσ )g2

Integrated Lumi: 5fb-

1

Same issues with detectorresolution as F2 and FL

in addition need to reduce systematics due to polarisation

E.C. Aschenauer

EIC EW Meeting, W&M, VA, May 2010 5

Kinematics

x

Q2

higher hadron energy at the same lepton beam energy allows access to lower x

higher lepton beam energy at the same hadron beam energy allows access to lower x

x =Q2

ys

Q2 =2EeEe'(1+cosθe')

E.C. Aschenauer

EIC EW Meeting, W&M, VA, May 2010 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

No dependence on hadron beam energyQ2>0.1GeV2

4GeV >5o

10GeV >2o

20GeV >1o

E.C. Aschenauer

EIC EW Meeting, W&M, VA, May 2010 7

Hadron Kinematics

4x100

4x250

4x250

4x1004x50

4x50

E.C. Aschenauer

EIC EW Meeting, W&M, VA, May 2010 8

Diffractive Physics: p’ kinematics

4 x 100

t=(p4-p2)2 = 2[(mpin.mp

out)-(EinEout - pz

inpzout)]

4 x 50

4 x 50

4 x 250

?

Diffraction:

E.C. Aschenauer

EIC EW Meeting, W&M, VA, May 2010 9

Current PHENIX Detector at RHIC

MPC 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

EIC EW Meeting, W&M, VA, May 2010 10

What will the current PheniX see4x100

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

EIC EW Meeting, W&M, VA, May 2010 11

HCALEMCAL

Preshower

The new PheniX Spectrometer Coverage in |h| =< 4 (2o < q < 30o) 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

60cm

2T SolenoidEMCAL

HCAL

Silicon TrackerVTX + 1 layer

Silicon TrackerFVTX

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

North Muon Arm

RICH

68cm

IP

80cm

145cm

5o @ 2m 17.4 cm dy

E.C. Aschenauer

12

IR-Design

E.C. Aschenauer EIC EW Meeting, W&M, VA, May 2010

0.4

4 m

Q5D5

Q4

90 m

10 mrad 0.3

29 m

3.67 mrad

60 m10 20 30

0.1

88036 m

18.8 m

16.8 m

6.33 mrad

4 m

© D.Trbojevic

30 GeV e-

325 GeV p

Or 125 GeV/u ions

eRHIC - Geometry high-lumi IR with β*=5 cm, l*=4.5 mand 10 mrad crossing angle

m

EIC EW Meeting, W&M, VA, May 2010 13

What can new PheniX do PROs:

large coverage for scattered lepton can do inclusive ep/eA physics through all stages of eRHIC can do semi-inclusive and exclusive physics, which needs muon

and electron-id (i.e. J/psi)

CONs: momentum and angular resolution critical for precision

inclusive physics material budget in central detector is on the high side

IPs are better offset to the center of the detector for asymmetric colliders very difficult because of symmetric design of central detector

NO PID and Muon-arm on forward direction most of semi-inclusive and exclusive/diffractive physics not possible

High Luminosity IR design does not work with old and new PheniX

need to move focusing quads lower luminosity

Remarks / Questions: need to integrate 10mrad bend in design need to integrate a luminosity measurementE.C.

Aschenauer

Summary:

the new PheniX detector can make

important measurements

in ep/eA

Lets integrate it into the design

and the next decadal plan