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A Detector for ( M)eRHIC

A Detector for ( M)eRHIC. Detector Requirements from Physics. ep -physics the same detector needs to cover inclusive ( ep -> e’X ), semi-inclusive ( ep -> e’hadron(s)X ) and exclusive ( ep -> e’p p ) reactions large acceptance absolutely crucial (both mid and forward-rapidity)

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A Detector for ( M)eRHIC

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  1. A Detector for (M)eRHIC EIC-IAC @ JLab, November 2009

  2. Detector Requirements from Physics EIC-IAC @ JLab, November 2009 • ep-physics • the same detector needs to cover inclusive (ep -> e’X), semi-inclusive (ep -> e’hadron(s)X) and exclusive (ep -> e’pp) reactions • large acceptance absolutely crucial (both mid and forward-rapidity) • particle identification is crucial • e, p, K, p, n over wide momentum range and scattering angle • excellent secondary vertex resolution (charm) • particle detection to very low scattering angle • around 1o in e and p/A direction  in contradiction to strong focusing quads close to IP • small systematic uncertainty for e/p polarization measurements • very small systematic uncertainty for luminosity measurement • eA-physics • requirements very similar to ep • challenge to tag the struck nucleus in exclusive and diffractive reactions.

  3. Event kinematics scattered lepton 20x250 4x250 D I S 4x50 175o 179o D I F F R A C T I V E without magnetic field EIC-IAC @ JLab, November 2009

  4. Event kinematics produced hadrons (p+) 20x250 D I S 4x50 4x250 DIS: small theta important D I F F R A C T I V E without magnetic field EIC-IAC @ JLab, November 2009

  5. Include: recoil proton plots and update the other ones for better visibility EIC-IAC @ JLab, November 2009

  6. ERL-based eRHIC Design 5 mm 5 mm 5 mm 5 mm 20 GeV e-beam 16 GeV e-beam Common vacuum chamber 12 GeV e-beam 8 GeV e-beam 2 x 200 m SRF linac 4 (5) GeV per pass 5 (4) passes eRHIC detector Gap 5 mm total 0.3 T for 30 GeV Polarized e-gun 10-20 GeV ex 325 GeV p 130 GeV/u Au possibility of 30 GeV @ low current operation Beam dump MeRHIC detector Coherent e-cooler PHENIX STAR 4 to 5 vertically separated recirculating passes EIC-IAC @ JLab, November 2009

  7. A Detector for Diffraction Design by Allen Caldwell: p EM Calorimeter Si tracking stations 2x14 Si tracking stations Compact – fits in dipole magnet with inner radius of 80 cm. Long - |z|5 m Hadronic Calorimeter e EIC-IAC @ JLab, November 2009

  8. First ideas for a detector concept Solenoid (4T) Dipol 3Tm Dipol 3Tm FPD FED // // ZDC • Dipoles needed to have good forward momentum resolution • Solenoid no magnetic field @ r ~ 0 • DIRC, RICH hadron identification p, K, p • high-threshold Cerenkov  fast trigger for scattered lepton • radiation length very critical  low lepton energies EIC-IAC @ JLab, November 2009

  9. IR-Design for MeRHIC I @ IP-2 • no synchrotron shielding included • IP-2: height beam-pipe floor ~6’ (with digging ~10’) EIC-IAC @ JLab, November 2009

  10. Diffractive events include 1 or 2 slides from Matt on diffractive studies for eA to make the point where the nuclei go, like Thomas slide 19 EIC-IAC @ JLab, November 2009

  11. Detection from hadron beam fragments EIC-IAC @ JLab, November 2009 • Tagging from Au fragments and p/n in ep • suppress incoherent scattering / ensure exclusivity • neutrons are detected in ZDC • protons use magnetic rigidity Au:p 2.5:1 • DX magnets disturbs p tagging

  12. IR-Design for MeRHIC IP-2 • no synchrotron shielding included • allows p and heavy ion decay product tagging • IP-2: height beam-pipe floor ~6’ (with digging ~10’) EIC-IAC @ JLab, November 2009

  13. First ideas for a detector concept Solenoid (4T) Dipol 3Tm Dipol 3Tm FPD FED // // ZDC • Dipoles needed to have good forward momentum resolution • Solenoid no magnetic field @ r ~ 0 • DIRC, RICH hadron identification p, K, p • high-threshold Cerenkov  fast trigger for scattered lepton • radiation length very critical  low lepton energies EIC-IAC @ JLab, November 2009

  14. Basis for Detector design explain the basis for the detector design, like dirc copy of Babar …. EIC-IAC @ JLab, November 2009

  15. MeRHIC Detector in Geant-3 Silicon Strip detector central tracking ala BaBar Drift Chambers • no hadronic calorimeter in barrel, because of vertical space @ IP-2 EIC-IAC @ JLab, November 2009

  16. MeRHIC Detector in Geant-3 EIC-IAC @ JLab, November 2009

  17. MeRHIC Detector in Geant-3 EIC-IAC @ JLab, November 2009

  18. Summary EIC-IAC @ JLab, November 2009 • Have done first steps on a detector design • Optimizations needed • magnetic fields • do we need 4T for solenoid and 3Tm for dipole • what radiation length can we tolerate @ low e’ momentum • optimize distance Dipole to Solenoid • impact of beam lines through the detector on physics • need to optimize acceptance at low scattering angle • need acceptance down to 1o • need to include lepton polarimeter in IR design • need to include luminosity monitor into IR design

  19. Start immediately at 12o’clock • Detector cost savings • have MeRHIC-detector @ IP-12 • fully staged detector from MeRHIC to eRHIC • vertical space much bigger • need to buy magnets only once • can stage detector components, i.e. hadronic calorimeter • no moving of components  only advantages EIC-IAC @ JLab, November 2009

  20. 12:00 experimental area EIC-IAC @ JLab, November 2009

  21. Work done @ JLAB EIC-IAC @ JLab, November 2009

  22. ELIC Detector/IR Layout solenoid ion FFQs dipole bending scattered protons “up” ions electrons IP with crossing angle electron FFQs Distance from IP to electron FFQ: 6 m to ion FFQ: 9m Modest electron final focusing quad field requirements  quads can be made small EIC-IAC @ JLab, November 2009

  23. ELIC detector cartoon - Oct. 09 8 meters (for scale) Offset IP? 140 degrees TOF HCAL ECAL Tracking DIRC HTCC RICH dipole dipole 1st (small) electron FF quad @ 6 m solenoid Additional electron detection (tracking, calorimetry) for low-Q2 physics not on cartoon Ion beam e beam EIC-IAC @ JLab, November 2009

  24. ELIC Detector Magnetic Field • Central 4T solenoid with 5 meter length and 4 meter ID • Need to add good particle identification detectors up to 40 • degrees on ion side  drives large ID to keep this area “open” • 4T field renders O(1%) or better momentum resolution for • particles with momentum < 10 GeV (and angles > 40 degrees) • Optimize detector to detect particles down to (at least) one degrees • Add 2-3 Tm dipole field to improve momentum resolution at • forward angles. • Two solutions: add dipole, or add dipole to solenoid? • Can in principle also have split dipole, with different polarity • before/after IP, if this helps accelerator design. • 5T solenoid with 0.6T dipole winding: • Integrated transverse (By) field strength • @ 90 degrees 10.9 Tm • @ 40 degrees 15.3 Tm • @ 1 degree 1.4 Tm • May present alternate solution if space is at a premium & 1.4 Tm sufficient field strength at 1o. • Note: all configurations iron free at moment Dipole coils EIC-IAC @ JLab, November 2009

  25. RecoilTagging in Deeply Virtual Exclusive Reactions on Nuclei e + AZ  e + AZ +(,,J/) k' k Determining exclusivity requires tagging the nucleus in the final state. The typical scale of transverse momentum transfer is given by the rms nuclear radius. q' Mm q ZP ZP' (for nuclei from 4He to 20Ne, this scale ranges from 125 MeV/c to 75 MeV/c) • For Nuclei ≥ 4He, the recoil nucleus is • INSIDEthe transverse admittance of the FF Quads • Qms≈ 1 mrPA,transverse ≈ Z·(60 MeV/c) (for 60 GeV ion beam) • Beam spread is larger than 1/RAscale for nuclear imaging. • Z·(60 MeV/c ) > (0.2 GeV/c)/A1/3 (≥75 MeV/c for AZ< 20Ne) • OUTSIDEthe longitudinal admittance of the ring lattice!!! • The nuclei may be detectable at high resolution with far forward tracking in the lattice by having large dispersion ELIC study EIC-IAC @ JLab, November 2009

  26. Far Forward Ion Tagging at (60 GeV/c) Z EIC-IAC @ JLab, November 2009 • Sample optics at token Roman Pot Telescope position • ELIC typical: Dispersion D = 1 m, Beta function b* = 2 m • ELIC typical: (x,Q) = (250 mm, 125 mr) rms • Use a 10sx Beam Stay Clear (BSC) distance  2.5 mm • Ions are detectable for |dPA||/PA| > BSC/D = 2.5 x 10-3. • Skewness 2z (~x/A) of Deep Virtual reaction = long. momentum fraction of a nucleon in projectile ion. • Skewness acceptance: 2z > (2.5x10-3)A  0.05 for 20Ne. • Assumption: 1 m drift with 100 mm spatial resolution • dQ = 100 mr equal to beam Qrms. • PA’ Momentum Resolution = sx/D = 2.5 x10-4. • D|| = (k-k’-q’) || = (PA’-PA’)|| • s(D||) = (4 x 10-4)(30 GeV/c) A = (12 MeV/c) A • Exclusivity constraint D2 = 2MA (PA’-PA) • Using ELIC arc as spectrometer to a longitudinal momentum transfer resolution of 10-4 by increasing dispersion @ IR will be explored in more detail

  27. BACKUP EIC-IAC @ JLab, November 2009

  28. Zeus @ HERA I EIC-IAC @ JLab, November 2009

  29. Zeus @ HERA II EIC-IAC @ JLab, November 2009

  30. Hera I vs Hera II Focusing Quads close to IP Problem for forward acceptance EIC-IAC @ JLab, November 2009

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