1. EIC Detectors Tanja Horn Tanja Horn, CUA Colloquium Tanja Horn, EIC Detectors, INT10-3 INT10-3 “Science Case for an EIC”, Institute for Nuclear Theory, UW, Seattle 16 November 2010 1

2. Science of an EIC: Explore and Understand QCD Tanja Horn, EIC Detectors, INT10-3 2 Map the spin and 3D quark-gluon structure of nucleons ̶ Image the 3D spatial distributions of gluons and sea quarks through exclusive J/ Ψ, γ (DVCS) and meson production ̶ Measure Δ G, and the polarization of the sea quarks through SIDIS, g1, and open charm production ̶ Establish the orbital motion of quarks and gluons through transverse momentum dependent observables in SIDIS and jet production Discover collective effects of gluons in nuclei ̶ Discover signatures of dynamics of strong color fields in nuclei at high energies in eA->e’X(or A) and eA->e’hadronsX ̶ Measure fundamental gluon/quark radii of nuclei through coherent scattering g* + A  J/Y + A ̶ Explore the nuclear modification of the nucleon's basic gluonic momentum and spatial structure through e + A  e‘ + X and e + A  e' + cc + X Understand the emergence of hadronic matter from quarks and gluons −Explore the interaction of color charges with matter (energy loss, flavor dependence, color transparency) through hadronization in nuclei in e + A  e' + hadrons + X −Understand the conversion of quarks and gluons to hadrons through fragmentation of correlated quarks and gluons and breakup in e + p  e' + hadron + hadron + X

3. C. Weiss s For large or small y, uncertainties in the kinematic variables become large Range in y Q 2 ~ xys Range in s Range of kinematics Detecting only the electron y max / y min ~ 10 Also detecting all hadrons y max / y min ~ 100 – Requires hermetic detector (no holes) Accelerator considerations limit s min – Depends on s max (dynamic range) At fixed s, changing the ratio E e / E ion can for some reactions improve resolution, pid, and acceptance – Luminosity may be lower than shown in profile C. Weiss valence quarks/gluons non-pert. sea quarks/gluons radiative gluons/sea [Weiss 09] s To cover the physics we need… 3 Tanja Horn, EIC Detectors, INT10-3

4. 1. To a large extent driven by exclusive physics 2. But not only... Hermeticity (also for hadronic reconstruction methods in DIS) Particle identification (also SIDIS) Momentum resolution (kinematic fitting to ensure exclusivity) Forward detection of recoil baryons (also baryons from nuclei) Muon detection ( J/Ψ ) Photon detection (DVCS) Very forward detection (spectator tagging, diffractive, coherent nuclear, etc) Vertex resolution (charm) Hadronic calorimetry (jet reconstruction) Detector Requirements Tanja Horn, EIC Detectors, INT10-3 4

5. Where do particles go - general p or A e Several processes in e-p: 1)“DIS” (electron-quark scattering)e + p  e’ + X 2)“Semi-Inclusive DIS (SIDIS)”e + p  e’ + meson + X 3)“Deep Exclusive Scattering (DES)”e + p  e’ + photon/meson + baryon 4)Diffractive Scatteringe + p  e’ + p + X 5)Target fragmentatione + p  e’ + many mesons + baryons Token example: 1 H(e,e’ π + )n 5 Tanja Horn, EIC Detectors, INT10-3 In general, e-p and even more e-A colliders have a large fraction of their science related to the detection of what happens to the ion beams. The struck quark remnants can be guided to go to the central detector region with Q 2 cuts, but the spectator quark or struck nucleus remnants will go in the forward (ion) direction. [Ent 10] Even more processes in e-A: 1)“DIS”e + A  e’ + X 2)“SIDIS”e + A  e’ + meson + X 3)“Coherent DES”e + A  e’ + photon/meson + nucleus 4)Diffractive Scatteringe + A  e’ + A + X 5)Target fragmentatione + A  e’ + many mesons + baryons 6)Evaporation processese + A  e’ + A’ + neutrons

6. 10 on 60 Modest (up to ~6 GeV) electron energies in central & forward-ion direction. Electrons create showers  electron detectors are typically compact. Scattered Electron Kinematics 6 Tanja Horn, EIC Detectors, INT10-3 low-Q 2 electrons in electron endcap high-Q 2 electrons in central barrel: 1-2 < p < 4 GeV Momentum (GeV/c) Electron Scattering Angle (deg) [Horn 08+] Larger energies (up to E e ) in the forward-electron direction: low-Q 2 events.

7. 7 4 on 250 GeV4 on 50 GeV diffractive DIS Both processes produce high-momentum mesons at small angles Small angle detection important for understanding target fragmentation Diffractive and SIDIS (TMDs) [W. Foreman 09] Tanja Horn, EIC Detectors, INT10-3 10° 5°

8. Tanja Horn, EIC Detectors, INT10-38 Horn 08+ recoil baryonsscattered electronsmesons 4 on 250 GeV 4 on 30 GeV  t/t ~ t/E p Θ~√t/E p PID challenging very high momenta electrons in central barrel, but p different 0.2 ° - 0.45 ° 0.2 ° - 2.5 ° ep → e'π + n Exclusive light meson kinematics

9. Nuclear Science: Map t between t min and 1 (2?) GeV  Must cover between 1 and 5 degrees  Should cover between 0.5 and 5 degrees  Like to cover between 0.2 and 7 degrees  = 5  = 1.3 E p = 12 GeVE p = 30 GeVE p = 60 GeV t ~ E p 2  2  Angle recoil baryons = t ½ /E p t resolution ~  ~ 1 mr 9 Tanja Horn, EIC Detectors, INT10-3 Where do particles go - baryons [Horn 08+]

10. DES at higher electron energies 4 on 305 on 50 10 on 50 Momentum (GeV/c) Lab Scattering angle (deg) 10 Tanja Horn, EIC Detectors, INT10-3 [Horn 08+] Need particle ID for p>4 GeV/c in central region A DIRC is not sufficient for π /K separation already at relatively modest energies Two options ̶ Supplement the DIRC with a C 4 F 8 O gas Cherenkov (threshold or RICH) ̶ Replace it with a dual radiator (aerogel/gas) RICH Most important for exclusive reactions, but also for SIDIS, etc.

11. 11 IP ultra forward hadron detection dipole low-Q 2 electron detection large aperture electron quads small diameter electron quads ion quads small angle hadron detection dipole central detector with endcaps EM Calorimeter Hadron Calorimeter Muon Detector EM Calorimeter Solenoid yoke + Hadronic Calorimeter Solenoid yoke + Muon Detector HTCC RICH Cerenkov Tracking 5 m solenoid 3° beam (crab) crossing angle TOF (+ DIRC ?) Apertures for small-angle ion and electron detection not shown Tanja Horn, EIC Detectors, INT10-3 MEIC interaction region and central detector layout

12. solenoid electron FFQs 50 mrad 0 mrad ion dipole w/ detectors (approximately to scale) ions electrons IP ion FFQs 2+3 m 2 m (“full-acceptance” detector) Three-stage strategy using 50 mrad crossing angle Detect particles with angles below 0.5° using 20 Tm dipole beyond ion FFQs. Distance IP – ion FFQs = 7 m (Driven by push to 0.5 degrees detection before ion FFQs) detectors Central detector, more detection space in ion direction as particles have higher momenta. Detect particles with angles down to 0.5° (10 mrad) before ion FFQs. Need 2 Tm dipole (for 100 GeV proton beams) in addition to central solenoid. 12 Tanja Horn, EIC Detectors, INT10-3 Forward Ion Detection

13. Detector Endcaps 13 Tanja Horn, Introduction to EIC/detector concept, Exclusive Reactions Workshop 2010 Bore angle: ~45° (line-of-sight from IP) High-Threshold Cerenkov (e/π) Time-of-Flight Detectors ̶ Hadrons, event reconstruction, trigger Electromagnetic Calorimeter (e/π) Bore angle: 30-40° (line-of-sight from IP) Ring-Imaging Cerenkov (RICH) Time-of-Flight Detectors (event recon., trigger) Electromagnetic Calorimeter ̶ P re-shower for γ/π° -> γγ (very small opening angle at high p) Hadronic Calorimeter (jets) Muon detector (J/Ψ production at low Q 2 ) Space constraints Electron side (left) Ion side (right) Electron side has a lot of space Ion side limited by distance to FFQ quads (7 m) EM Calorimeter Hadron Calorimeter Muon Detector EM Calorimeter TOF HTCC RICH Tracking Tanja Horn, EIC Detectors, INT10-3 13

14. Central Detector 14 Tanja Horn, Introduction to EIC/detector concept, Exclusive Reactions Workshop 2010 3-4 T solenoid with about 4 m diameter Hadronic calorimeter and muon detector integrated with the return yoke (c.f. CMS) TOF for low momenta π/K separation options –DIRC up to 4 GeV –DIRC + LTCC (or dual radiator RICH): up to 9 GeV p/K separation ̶ DIRC up to 7 GeV e/π separation –C 4 F 8 O LTCC up to 3 GeV Solenoid Yoke, Hadron Calorimeter, Muons Particle Identification Low-mass vertex tracker GEM-based central tracker Conical endcap trackers Solenoid yoke + Hadronic Calorimeter Solenoid yoke + Muon Detector LTCC / RICH Tracking Tracking Tanja Horn, EIC Detectors, INT10-3 14

15. Δp/p ~ σp / BR 2 175° R1R1 R2R2 Crossing angle A 2 Tm dipole covering 3-5° eliminates divergence at small angles Only solenoid field B (not R) matters at very forward rapidities A 3° beam crossing angle moves the region of poor resolution away from the ion beam center line. – 2D problem! Tracker (not magnet!) radius R is important at central rapidities – Conical trackers improve resolution at endcap corners by (R 2 /R 1 ) 2 ~ 4 (not shown) position resolution σ ~ 100 microns – CLAS DCs designed for 150 microns particle momentum = 5 GeV/c 4 T ideal solenoid field cylindrical tracker with 1.25 m radius (R 1 ) Goal: dp/p ~ 1% @ 10 GeV/c 15 Tanja Horn, EIC Detectors, INT10-3 Resolution dp/p in solenoid

16. Present thinking: ion beam has 50 mr horizontal crossing angle Renders good advantages for very-forward particle detection 20 Tm dipole @ ~20 m from IP (Reminder: MEIC/ELIC scheme uses 50 mr crab crossing) 16 Tanja Horn, EIC Detectors, INT10-3 Use Crab Crossing for Very-Forward Detection [Zhang09+] ions

17. 17 IP electrons ions 8 m drift space after low-Q 2 tagger dipole Chromaticity Compensation Block IR Spin Rotator Arc end Chromaticity Compensation Block Arc end Very forward ion tagging 20 Tm analyzing dipole Tanja Horn, EIC Detectors, INT10-3 MEIC Interaction Region – forward tagging [Bogacz 10]

18. 18 Tanja Horn, EIC Detectors, INT10-3 Detector/IR – Forward & Very Forward Ion Final Focusing Quads (FFQs) at 7 meter, allowing ion detection down to 0.5 o before the FFQs (BSC area only 0.2 o ) Use large-aperture (10 cm radius) FFQs to detect particles between 0.3 and 0.5 o (or so) in few meters after ion FFQ triplet  x-y @ 12 meters from IP = 2 mm 12  beam-stay-clear  2.5 cm 0.3 o (0.5 o ) after 12 meter is 6 (10) cm Large dipole bend @ 20 meter from IP (to correct the 50 mr ion horizontal crossing angle) allows for very-small angle detection (< 0.3 o )  x-y @ 20 meters from IP = 0.2 mm 10  beam-stay-clear  2 mm 2 mm at 20 meter is only 0.1 mr…  (bend) of 29.9 and 30 GeV spectators is 0.7 mr = 2.7 mm @ 4 m Situation for zero-angle neutron detection very similar as at RHIC!  enough space for Roman Pots & small-angle calorimeters [Slide from R. Ent 10]

19. From arc where electrons exit and magnets on straight section Synchrotron radiation Random hadronic background Dominated by interaction of beam ions with residual gas in beam pipe between arc and IP Comparison of MEIC (at s = 4,000) and HERA (at s = 100,000) Comparison of MEIC (at s = 4,000) and HERA (at s = 100,000) −Distance from ion exit arc to detector: 50 m / 120 m = 0.4 −Average hadron multiplicity: (4000 / 100000) 1/4 = 0.4 −p-p cross section (fixed target): σ(90 GeV) / σ(920 GeV) = 0.7 −At the same ion current and vacuum, MEIC background should be about 10% of HERA o Can run higher ion currents (0.1 A at HERA) o Good vacuum is easier to maintain in a shorter section of the ring Backgrounds do not seem to be a major problem for the MEIC Backgrounds do not seem to be a major problem for the MEIC −Placing high-luminosity detectors closer to ion exit arc helps with both background types −Signal-to-background will be considerably better at the MEIC than HERA o MEIC luminosity is more than 100 times higher (depending on kinematics) Backgrounds and detector placement 19 Tanja Horn, EIC Detectors, INT10-3

20. 20 EM Calorimeter Hadron Calorimeter Muon Detector EM Calorimeter Solenoid yoke + Hadronic Calorimeter Solenoid yoke + Muon Detector HTCC RICH Cerenkov Tracking 5 m solenoid JLab layout has conical rather than cylindrical forward / backward trackers (with line-of-sight from IP) JLab detector does not have the forward RICH inside the solenoid magnet JLab detector reserves space for DIRC readout (but details need to be worked out!) JLab detector allocates space for Cerenkov (LTCC) in central barrel for high-momentum PID JLab interaction region has a larger ion beam crossing angle 50-60 mrad vs 10 mrad Minor differences Tanja Horn, EIC Detectors, INT10-3 JLab and BNL central detector layouts similar JLabBNL[Nadel-Turonski talk week 5] [Aschenauer talk week 1&8]

21. eRHIC Detector Concept Tanja Horn, EIC Detectors, INT10-3 21 Forward / Backward Spectrometers: 2m 4m  central detector acceptance: very high coverage -5 <  < 5  Tracker and ECal coverage the same  crossing angle: 10 mrad;  y = 2cm and  x = 2/4cm (electron/proton direction)  Dipoles needed to have good forward momentum resolution and acceptance  DIRC, RICH hadron identification  , K, p  low radiation length extremely critical  low lepton energies  precise vertex reconstruction (< 10  m)  separate Beauty and Charmed Meson minimum angle for “elastic protons” to be detected in the main detector 10 mrad  p t = 1 GeV [Aschenauer talk week 1&8]

22. IR-Design-Version-I 0.44 m Q5 D5 Q4 90 m 10 mrad 0.329 m 3.67 mrad 60 m 10 20 30 0.188036 m 18.8 m 16.8 m 6.33 mrad 4 m Dipole © D.Trbojevic 30 GeV e - 325 GeV p 125 GeV/u ions eRHIC - Geometry high-lumi IR with β*=5 cm, l*=4.5 m and 10 mrad crossing angle Assume 50% operations efficiency  4fb -1 / week Tanja Horn, EIC Detectors, INT10-3 22 Spinrotator [Aschenauer talk week 1]

23. 2 468 10 2.5 m 3.5 m 1214 90 mm 5.75 m 16 IP Dipole: 2.5 m, 6 T  =18 mrad 4.5 m  =18 mrad  =10 mrad Estimated  * ≈ 8 cm  =44 mrad 6.3 cm ZDC p c /2.5 15.7 cm 6 mrad 11.2 cm 4.5 cm neutrons p c /2.5 IP configuration for eRHIC – Version-II 23 Tanja Horn, EIC Detectors, INT10-3 e Quad Gradient: 200 T/m [Aschenauer talk week 8]

24. 0.44843 m Q5 D5 Q4 90.08703 m 10 mrad 0.39065 m 60.0559 m 10 20 30 0.333 m IP configuration for eRHIC – Version-II Tanja Horn, EIC Detectors, INT10-3 24 4 m 4.5  =18 mrad 5.75 m 5.75 cm 11.9 m 17.65 m  =27.194 mrad [Aschenauer talk week 8]

25. Summary Tanja Horn, EIC@JLab - taking nucleon structure beyond the valence region, INT09-43W 25 Tanja Horn, EIC Detectors, INT10-3 JLab and BNL detector concepts generally similar Emphasis on small-angle coverage ̶ Three stage approach for forward hadron detection Detector is well suited for a wide range of experiments Integration with accelerator important Goal: hermetic detector with high resolution over full acceptance

26. Backup material Tanja Horn, EIC@JLab - taking nucleon structure beyond the valence region, INT09-43W 26 Tanja Horn, EIC Detectors, INT10-3

27. 4 on 60 Modest (up to ~6 GeV) electron energies in central & forward-ion direction. Electrons create showers  electron detectors are typically compact. Larger energies (up to E e ) in the forward-electron direction: low-Q 2 events. Requirements on the electron side are dominated by near-photon physics: electrons need to be peeled away from beam by tagger magnet(s). Momentum (GeV/c) Scattered Electron Kinematics 27 Tanja Horn, EIC Detectors, INT10-3 low-Q 2 electrons in electron endcap high-Q 2 electrons in central barrel: 1-2 < p < 4 GeV

28. Kinematic Coverage Tanja Horn, EIC Detectors, INT10-3 x ~ Q 2 /ys mEIC at JLab, 11 on 60 GeV JLab 12 GeV H1 ZEUS HERA, y=0.004 mEIC 3 on 20, y=0.004 x Q 2 (GeV 2 ) [Nadel-Turonski 09] 28 x Q 2 (GeV 2 ) High Density Matter Nuclear Structure & Low x Parton Dynamics High precision partons in LHC plateau Large x partons New physics on scales ~10 -19 LHeC Experiment Overlaps with HERA and the LHeC Overlaps (or close to overlap) with JLab 12 GeV Gives an order of magnitude higher reach in s than COMPASS and a much higher luminosity s (CM energy) A medium-energy EIC is complementary to the LHeC

29. Detector/IR in pocket formulas  max ~ 2 km = l 2 /  * (l = distance IP to 1 st quad) IP divergence angle ~ 1/sqrt(  *) Luminosity ~ 1/  * Example: l = 7 m,  * = 20 mm   max = 2.5 km Example: l = 7 m,  * = 20 mm  angle ~ 0.3 mr Example:12  beam-stay-clear area  12 x 0.3 mr = 3.6 mr ~ 0.2 o Making  * too small complicates small-angle (~0.5 o ) detection before ion Final Focusing Quads, and would require too high a peak field for these quads given the large apertures (up to ~0.5 o ).  * = 1-2 cm and E p = 20-60+ GeV ballpark right! FFQ gradient ~ E p,max /sqrt(  *) (for fixed  max, magnet length) Example:6.8 kG/cm for Q3 @ 12 m @ 60 GeV  7 T field for 10 cm (~0.5 o ) aperture 29 Tanja Horn, EIC Detectors, INT10-3