The Physics of eRHIC

• Introduction• Scientific highlights• Detectors• Summary

R. Milner8th Conference on Intersections

of Particle and Nuclear Physics

New YorkMay 23rd, 2003

The Electron-Ion Collider (EIC)• Substantial international interest in high luminosity

(~1033cm-2s-1) polarized electron-ion collider over last several years• Workshops

Seeheim, Germany 1997

IUCF, USA 1999

BNL, USA 1999

Yale, USA 2000

MIT, USA 2000• Electron Ion collider (EIC) received very favorable review of science

case in US Nuclear Physics Long Range Plan, with strong endorsement for R&D

• At BNL Workshop in March 2002, EIC Collaboration has formulated a plan to produce a conceptual design within three years using RHIC : eRHIC

• NSAC in March 2003, declared eRHIC science `absolutely central’ to Nuclear Physics

The Electron Ion Colliderhttp://www.bnl.gov/eic

• Slide-report of the Joint DESY/GSI/NuPecc Workshop on Electron-Nucleon/Nucleus Collisions, March 3-4, 1997, Lufthansa-Zentrum Seeheim, Germany, GSI Report 97-04.

• Proceedings of the Workshop on Physics with a High Luminosity Polarized Electron Ion Collider (EPIC99), April 8-11, 1999, Bloomington, Indiana, USA, Editors L.C. Bland, J.T. Londergan, and A.P. Szczepaniak, World Scientific.

• Proceedings of the eRHIC Workshop, December 3-4, 1999, Brookhaven National Laboratory.

• Proceedings of the Second eRHIC Workshop, April 6-8, 2000, Yale University, New Haven, Connecticut, USA, BNL Report 52592.

• Proceedings of the Second Workshop on Physics with an Electron Polarized Light Ion Collider (EPIC 2000), September 14-16, 2000, MIT, Cambridge, MA, USA, Editor R.G. Milner, AIP Conference Proceedings No. 588.

• Proceedings of the Electron Ion Collider Workshops, February 26-March 2, 2002, Brookhaven National Laboratory, Editors M.S. Davis, A. Deshpande, S. Ozaki, R. Venugopalan BNL-52663-V.1 and V.2.

eRHIC is a powerful new tool required for the study of the fundamental structure of matter

• 99.9% of observable matter in the physical universe is in the form of atomic nuclei

• To a good approximation, nuclei are systems of bound nucleons

• QCD tells us that the nucleon is made of pointlike constituents bound by powerful gluon fields

x is the momentum of the quark or gluon where is the spatial distance scale probed

• A new facility which directly probes the quarks and gluons is demanded

Lepton probeHigh center of mass energyHigh luminosity precisionPolarized lepton, nucleonOptimized detectors

2

2

1~Q

Why a Collider ?

• High Ecm large range of x, Q2

x range: valence, sea quarks, glue

Q2 range: utilize evolution equations of QCD

• High polarization of lepton, nucleon achievable

• Complete range of nuclear targets

• Collider geometry allows complete reconstruction of final state

2 2max cmQ E x

Q2 and x Range of eRHIC

Scientific Highlights• nucleon structure

sea quarks and gluespin and flavor structurenew parton distributions

• Meson structure, K are Goldstone Bosons of QCDessential to nuclear binding

• hadronizationevolution of parton into hadronprocess in nuclei of fundamental interest

• nucleirole of partonsinitial conditions for relativistic heavy ion collisions

• matter under extreme conditionssaturation of parton distributionsnew phenomena, e.g. colored glass condensate

Spin structure function g1 of proton low xx = 10-4 0.7Q2 = 0 104 GeVeRHIC 250 x 10 GeV

Lumi=85 inv. pb/day

x = 10-3 0.7Q2 = 0 103 GeVFixed target experiments1989 – 1999 Data

10 days of eRHIC runAssume: 70% Machine Eff. 70% Detector Eff.

Structure of the Goldstone Bosons

Light mesons: pions and kaons

• important role in nuclear physics

• important component of nucleon structure

• approximate chiral symmetry

• Goldstone bosons of chiral models

• nuclear medium effects

- In collider kinematics the pion can be probed essentially on

shell.

- with light nuclear projectiles, pions and kaons in medium can

be studied.

- Partonic origin of nuclear binding

Pion Structure Function with eRHIC

Expected Errors for 1 day of eRHIC running

Quark momentum distribution of pion

Using Nuclei to Increase the Gluon Density

• Parton density at low x rises as• Unitarity saturation at some• In a nucleus, there is a large enhancement of the parton

densities / unit area compared to a nucleon

•

ExampleQ2=4 (GeV/c)2

< 0.3 A = 200

Xep=10-7 for XeA = 10-4

1x

2sQ

2 1 13 3

2

/

/

6 for 200

A A A

N N N

G R GA A

G r AG

A

2

21

134

3

eA s

ep s

X Qx Q

A

Gluon Momentum Distribution from DIS

RHIC Data consistent with Gluon Saturation

eRHIC Detectors

• central detector 30° < < 160 °trackingcalorimetryparticle i.d.jet reconstructionluminosity measurement

e.g. ZEUS detector at HERA

• suite of dedicated detectors at small angles– Forward, rear detectors to increase acceptance– Complete event detector in eA (M.W. Krasny)– Low t measurements e.g. DVCS, Sullivan process

• Detailed simulations underway

The Hadron Side of the Krasny Detector

Summary

• eRHIC covers a CM energy range from 30 to 100 GeV and is essential to a systematic study of QCD phenomena

• eRHIC will address key questions - spin and flavor structure of nucleon - new parton distributions - structure of Goldstone bosons - role of partons in nuclei - search for new phenomena• Conceptual design of eRHIC machine and scientific

equipment under development

Core Group:• Accelerator & IR Design

V. Ptitsyn (BNL) + team BNL/Bates

• Physics Coordination

A. Deshpande(RBRC)

Theory principle contacts:

W. Vogelsang (BNL)&

R. Venugopalan (BNL)

Monte Carlo Generators

N. Makins (UIUC) + team

Detector Simulation Tool

B. Surrow (BNL)

DAQ and Trigger Issues

(BNL+Colorado+Others)

Detector Technology

(BNL+LBNL+MIT+Kyoto+RBRC+Others)

Authors of Electron Ion Collider White PaperArgonne National Laboratory

R. Holt, P. Reimer

Brookhaven National Laboratory

I. Ben Zvi, J. Kewischm, T. Ludlam, L. McLerran, J. Murphy, S. Peggs, P. Paul, T. Roser, B Surrow, R. Venugopalan

Budker Institute of Nuclear Physics, Russia

I.A. Koop, M.S. Korostelev, I.N. Nesterenko, A.V. Otboev, V.V. Parkhomchuk, E.A. Perevedentsev, V.B. Reva,

V.G. Shamovsky, D.N. Shatilov, P. Yu. Shatunov, Yu. M. Shantunov, A.N. Skrinsky

CERN, Switzerland

A. De Roeck

University of Colorado at Boulder

E.R. Kinney, U. Stoesslein

Fermi National Laboratory

V.A. Lebedev, S. Nagaitsev

University of Illinois at Urbana-Campaign

N. Makins

Indiana University Cyclotron Facility and Indiana Univserity

J. Cameron, T. Londergan, P. Schwandt

Thomas Jefferson Laboratory

Y. Derbenev, G.A. Drafft, R. Ent, L. Merminga, C. Sinclair

Lawrence Berkley National Laboratory

X. Wang

Los Alamos National Laboratory

G. Garvey

Massachusetts Institute of Technology

A. Bruell, W. Graves, D. Hasell, K. Jacobs, R. Milner, K. Takase, C. Tschalaer, F. Wang, A. Zolfaghari

Institute of Nuclear Physics, Poland

J. Chwastowski

University of Paris VI, France

E. Barrelet, M.W. Krasny

Pennsylvania State University

M. Strikman

University of Regensburg, Germany

A. Freund, A. Schaefer, M. Stratmann

RIKEN-BNL Research Center

A. Deshpande, M. G. Perdekamp, N. Saito

Saclay, France

G. Radel

TRIUMF, Canada

A. Miller

Yale University

V.W. Hughes

eRHIC Accelerator & IR Design Group• J.Kewisch, B.Parker, S.Peggs, V.Ptitsyn, D.Trbojevic (BNL)• D.E.Berkaev, I.A.Koop, A.V.Otboev, Yu.M.Shatunov (BINP)• C.Tschalaer, J.B. van der Laan, F.Wang (MIT-Bates)• D.P.Barber (DESY)