Some thoughts to stimulate Discussion E.C. Stony Brook, January 20101

Detector Requirements from Physics E.C. Aschenauer Stony Brook, January  ep-physics  the same detector needs to cover inclusive (ep -> e’X), semi-inclusive (ep -> e’hadron(s)X) and exclusive (ep -> e’p  reactions energy variability p: 50 – 250/325 e: energy variability p: 50 – 250/325 e: large acceptance absolutely crucial (both mid and forward-rapidity) large acceptance absolutely crucial (both mid and forward-rapidity) particle identification is crucial particle identification is crucial e, , K, p, n over wide momentum range and scattering angle excellent secondary vertex resolution (charm) particle detection to very low scattering angle particle detection to very low scattering angle around 1 o in e and p/A direction around 1 o in e and p/A direction  in contradiction to strong focusing quads close to IP  small systematic uncertainty (~1%/~3%) for e/p polarization measurements  very small systematic uncertainty (~1%) for luminosity measurement  eA-physics  requirements very similar to ep challenge to tag the struck nucleus in exclusive and diffractive reactions. difference in occupancy must be taken into account

Energies Simulated in RAPGAP Beam Energies E e + E p [GeV] Center-of-mass Energy [GeV] Events Produced One million E.C. Aschenauer Stony Brook, January 2010

(M)eRHIC Luminosities E.C. Aschenauer Stony Brook, January Some luminosity numbers: for MeRHIC without CEC 4 x 250: 1x10 32 cm -2 s -1 for MeRHIC with CEC 4 x 250: 1x10 33 cm -2 s -1 for eRHIC with CEC: 20 x 325: 2.8x10 33 cm -2 s x 325 with b* of 5cm: 1.4x10 34 cm -2 s -1 as the the luminosity does not depend on the energy of electron beam you can write it as for eRHIC with CEC: * E p /250 cm -2 s -1 so you can easily scale it going to 20x100 for example so for MeRHIC assuming 50% operations efficiency one week corresponds to 0.5 * (s in a week) * (1x10 32 cm -2 s -1 ) = 3*10 37 cm -1 so 30pb -1 for eRHIC with CEC we collect in one week ~1fb an operations efficiency of 50% is low, but conservative at this moment. For EIC systematic errors will be the limiting factor For EIC systematic errors will be the limiting factor i.e., g 1, F L,  g,  q i.e., g 1, F L,  g,  q

The √s vs. minimum luminosity landscape E.C. Aschenauer BNL S&T-Review, July semi-inclusive DIS inclusive DIS Diffraction electro-weak 4x100 10x100 20x100 20x250 exclusive DIS (DVCS) exclusive DIS (PS & VM) 4x50 H1/ZEUS: ~10 31 cm -2 s -1 Hermes: 5x W 2 -dependence of c.s. neglected

Momentum vs. theta of scat. electron 6 Proton Energy 50 GeV 100 GeV 250 GeV Electron Energy 4 GeV 10 GeV 20 GeV 4 GeV 10 GeV 20 GeV E.C. Aschenauer Stony Brook, January 2010 As more symmetric beam energies as more the scattered lepton goes forward

7 E.C. Aschenauer Stony Brook, January x50 4x100 4x250 p e : 0-1 GeV p e : 1-2 GeV p e : 2-3 GeV p e : 3-4 GeV Q 2 >1GeV 2  20 o after 1m ~35cm away from beam pipe

Momentum vs. angle of pions Same CM energy (63.3 GeV) What do we see:  For DIS: distribution is more “smeared” as energy balance becomes more symmetric  For diffractive: majority of pions at easily accessible angles, either forward or backward depending on proton/electron energy 8

t for exclusive VM vs p’ angle E.C. Aschenauer Stony Brook, January x 50 4 x x 250 very strong correlation between t and “recoiling” proton angle  Roman pots need to be very well integrated in the lattice well integrated in the lattice  resolution on t! t=(p 4 -p 2 ) 2 = 2[(m p in.m p out )-(E in E out - p z in p z out )] t=(p 3 –p 1 ) 2 = m ρ 2 -Q 2 - 2(E γ* E ρ -p x γ* p x ρ -p y γ* p y ρ -p z γ* p z ρ )

IR-Design for MeRHIC IP-2 E.C. Aschenauer Stony Brook, January  no synchrotron shielding included  allows p and heavy ion decay product tagging  IP-2: height beam-pipe floor ~6’ (with digging ~10’)

First ideas for a detector concept E.C. Aschenauer Stony Brook, January Dipole3Tm Dipole3Tm Solenoid (4T) ZDC FPD FED // //  Dipoles needed to have good forward momentum resolution  Solenoid no magnetic r ~ 0  DIRC, RICH hadron identification  , K, p  high-threshold Cerenkov  fast trigger for scattered lepton  radiation length very critical  low lepton energies

MeRHIC Detector in Geant-3 E.C. Aschenauer Stony Brook, January  DIRC: not shown because of cut; modeled following Babar  no hadronic calorimeter in barrel, because of vertical IP-2 Drift Chambers centraltracking ala BaBar Silicon Strip detector ala Zeus EM-CalorimeterLeadGlas High Threshold Cerenkov fast trigger on e’ e/h separation Dual-RadiatorRICH ala HERMES Drift Chambers ala HERMES FDC

E.C. Aschenauer Stony Brook, January BACKUP

E.C. Aschenauer Stony Brook, January STAR PHENIX 2 x 200 m SRF linac 4 (5) GeV per pass 5 (4) passes Polarizede-gun Beamdump 4 to 5 vertically separated recirculating passes Coherente-cooler 5 mm 20 GeV e-beam 16 GeV e-beam 12 GeV e-beam 8 GeV e-beam Common vacuum chamber Gap 5 mm total 0.3 T for 30 GeV (M)eRHICdetector MeRHICdetector GeV e x 325 GeV p 130 GeV/u Au possibility of 30 low current operation ERL-based eRHIC Design

HERA I E.C. Aschenauer Stony Brook, January

HERA II E.C. Aschenauer Stony Brook, January

Hera I vs. Hera II E.C. Aschenauer Stony Brook, January Focusing Quads close to IP Problem for forward acceptance

ions electrons solenoid dipole bending scattered protons “up” IP with crossing angle electron FFQs ion FFQs Distance from IP to electron FFQ: 6 m to ion FFQ: 9m to ion FFQ: 9m Electron FF quad Distance from IP lengthField strength Beam size  3 GeV Beam size  3 GeV Quad 16.0 meter50 cm-1.14 kG/cm 5 mm4 mm Quad meter120 cm0.71 kG/cm 8 mm3 mm Quad 38.7 meter50 cm-0.75 kG/cm 4 mm Modest electron final focusing quad field requirements  quads can be made small ELIC Detector/IR Layout E.C. Aschenauer Stony Brook, January by R. Ent

8 meters (for scale) 140 degrees Tracking TOF dipole solenoid RICH ECAL DIRC HCAL HTCC Offset IP? Ion beam e beam dipole 1 st (small) electron FF 6 m ELIC detector cartoon - Oct. 09 E.C. Aschenauer Stony Brook, January Additional electron detection (tracking, calorimetry) for low- Q 2 physics not on cartoon by R. Ent

Event kinematics produced hadrons (  + ) E.C. Aschenauer Stony Brook, January DIS DIFFRACTIVE 4x50 4x250 withoutmagneticfield DIS:smallthetaimportant 20x250