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First Concepts for an Detector

First Concepts for an Detector. Requirements from Physics. ep-physics the detector needs to cover inclusive  semi-inclusive  exclusive reactions large acceptance absolutely crucial particle identification ( p ,K,p,n) over wide momentum range excellent vertex resolution (charm)

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First Concepts for an Detector

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  1. First Concepts for anDetector DIS – Madrid, April 2009

  2. Requirements from Physics • ep-physics • the detector needs to cover inclusive  semi-inclusive  exclusive reactions • large acceptance absolutely crucial • particle identification (p,K,p,n) over wide momentum range • excellent vertex resolution (charm) • particle detection for very low scattering angle • uncertainty for e/p polarization measurements • luminosity measurement uncertainty • eA-physics • requirements very similar to ep • most challenging get information on recoiling heavy ion from exclusive and diffractive reactions. DIS – Madrid, April 2009

  3. Where do the electrons and quarks go

  4. eRHIC vs. ELIC • Machine parameters crucial for a the detector • interaction rate • ELIC: 500MHz  a bunch every 2ns • eRHIC: 13MHz  a bunch every 70ns • e-beam current  synchrotron rate • ELIC: 0.55 A • eRHIC: 0.26 A • Hera: 0.050 A • IP design  vacuum DIS – Madrid, April 2009

  5. First ideas for a detector concept / TRD DIS – Madrid, April 2009

  6. Detector Magnetic Field • by Tanja Horn, Rolf Ent and Richard Milner • Magnetic Field configration • Solenoid is “easy” field, but not much field at small scattering angles • Toroid would give better field at small (~5 degrees) angles with an asymmetric acceptance • Improves acceptance for positive hadrons (outbending) • Improves detection of high Q2 electrons (inbending) • Limits acceptance at very small angles (~3o) due to coils • May limit acceptance for π+π- detection • Vary Solenoid field to see how far one can push and compare with toroidal field • But … may not want too large a central solenoid field to access low-momentum reaction products from e.g. open charm production (~0.5 GeV/c) • Could also add central toroidal or dipole field(s) to solenoid • Small dipole component may be useful for lattice design (~0.3-0.5 Tm?) • goal of dipole field on electron side to optimize resolutions • goal of dipole field on hadron side to “peel” charged particles away from beam E.C. Aschenauer

  7. Simulation of Resolutions Multiple scattering contribution: Intrinsic contribution (first term): • z = charge of particle • L = total track length through detector (m) • γ= angle of incidence w.r.t. normal of detector plane • nr.l. = number of radiation lengths in detector msc • B=central field (T) • σrφ=position resolution (m) • L’=length of transverse path through field (m) • N=number of measurements intr • Assumptions: • circular detectors around interaction point • nr.l. = 0.03 (from Hall D CDC) • all simulations done for pions !!! E.C. Aschenauer

  8. “Easier” Solenoid Field – 2T vs. 4T? p = 50 GeV p = 5 GeV B=2T B=4T • Intrinsic contribution ~ 1/B • Multiple scattering contribution ~ 1/B

  9. Include dipole field p = 50 GeV p = 5 GeV As expected, substantially improves resolutions at small angles

  10. Beam Induced Detector Background • Beam particles-residual gas interaction • a) Coulomb scattering • b) Bermsstrahlung • 2) Synchrotron radiation • a) direct radiation generated in upstream magnets • b) backward scattering from down stream components • c) forward from mask tip and upstream vacuum chamber • 3) Touschek Scattering • only important for low energy colliders • 4) Thermal Photon Compton Scattering • only important for very high energy colliders • Beam-beam interaction • 6) Operational particle losses • Injection, machine tuning, beamloss, etc. E.C. Aschenauer

  11. What was seen at HERA Pressure development E.C. Aschenauer

  12. What was seen at HERA Pressure during Lumi Fill E.C. Aschenauer

  13. What was seen at HERA proton beam gas background E.C. Aschenauer

  14. Absolute Polarimeter (H jet) RHIC pC Polarimeters Siberian Snakes Spin flipper PHENIX STAR Spin Rotators (longitudinal polarization) Spin Rotators (longitudinal polarization) Solenoid Partial Siberian Snake LINAC BOOSTER Helical Partial Siberian Snake Pol. H- Source AGS 200 MeV Polarimeter AGS Polarimeters Strong AGS Snake The RHIC Accelerator MEeIC 4 GeV electrons DIS – Madrid, April 2009

  15. Main ERLs; 6 cryomodules x 6 cavities x 18 Mev/cav = 0.65 MeV per linac 4 GeV pass DX DX D0, Q1,Q2,Q3 0.1, 1.4, 2.7 GeV passes Recirculation passes: 0.75, 2.05, 3.35 GeV Polarized Electron Source 90 MeV ERL MeRHIC at IR 2 IR2 region: - asymmetric detector hall is very appropriate for asymmetric detector for e-p collisions - long wide (7.3m) tunnel on one side from the IR is good to place the ERLs Detector hall accommodates also the injector system (polarized gun, bunching system, pre-accelerator ERL) and the beam dump. Recirculation passes are going outside of the existing tunnel: warm magnets, acceptable synchrotron radiation power. DIS – Madrid, April 2009

  16. 95 MeV ERL IR2 Hall: Detector and Injector System Soft bend 0.05T, 1m Beam Dump 250 (500) kW Bunching section Wien Spin rotator Polarized gun 200 keV DC with combiner cavity 5 (10) MeV Linac DIS – Madrid, April 2009

  17. Synchrotron Radiation into eRHIC IR Two directions of synchrotron radiation in the eRHIC IR: Forward (direction of the electrons) generated by 10GeV electrons bent through a 0.2 Tesla detector integrated dipole magnet located 1m (from the magnet center to IP) upstream. Backward (opposite direction of the electrons) caused by the secondary radiation of the absorber located 7.2m downstream, (proportional to the primary radiation on the absorber.) In the current design, the fraction of the forward radiation fan hitting the absorber is 20% and 27%, generated in the magnets located 1m (from the magnet center to IP) upstream and downstream of the detector, respectively. E.C. Aschenauer

  18. Detector Synchrotron Radiation Background • 1. A horizontal hard bend and a vertical soft bend on both side of the detector; • The forward radiation from the up stream hard bend (red) is completely masked. No hard radiation passes through the detector; • The forward radiation from the up stream soft bend (blue) will pass through the detector without hitting detector wall. • 4. The secondary backward radiation induced by the forward radiation generated in down stream bends will be largely masked from the detector; • 5. The detector radiation background due to multiple scattering from the vacuum system, masks, collimators and absorbers will be investigated with computer simulations. Forward Radiation Spectrum The photon spectrum of forward synchrotron radiation: P0 = synchrotron radiation power g = electron relativistic factor (Eetotal/Eerest) EC = the critical photon energy S-function defined as: K5/3(z) = the modified Bessel function of the second kind.

  19. Solenoid (4T) Dipole ~3Tm Accelerator and detector integration and SR protection J.Beebe-Wang, C.Montag, B.Parker, D.Trbojevic Dipole ~3Tm To provide effective SR protection: -soft bend (~0.05T) is used for final bending of electron beam -combination of vertical and horizontal bends DIS – Madrid, April 2009

  20. The ELIC Design Medium Energy IP The tunnel houses 3 rings: Electron ring up to 5 GeV/c Ion ring up to 5 GeV/c Superconductiong ion ring for up to 30 GeV/c DIS – Madrid, April 2009

  21. IP Magnet Layout and Beam Envelopes 0.5m 3.2kG/cm 0.2m 22.2 mrad 1.27 deg 3.8m 0.6m 2.55kG/cm 8.4cm 10cm IP 1.8m 20.8kG/cm 22.9cm 3m 12KG/cm Vertical intercept Vertical intercept 14.4cm 16.2cm 4.5m Vertical intercept electron 4mm 5mm ion ELIC β*OK

  22. Optimization IP configuration optimization “Lambertson”-type final focusing quad Crab crossing angle  22mrad ELIC: IR Final Quad IR Final Quad Electron (10 GeV) 2.4cm 2.4cm 8.6cm 14cm 4.6cm 10 cm 10cm 4.8cm 3cm Proton (250 GeV) 3cm 1.8m 20.8kG/cm 1st SC focusing quad for ion

  23. Synchrotron Power/Backgrounds • Synchrotron radiation in IR : lower electron energy than HERA! • Synchrotron Power ~ I E4 / R • ELIC / HERA II current ratio: ~ 0.55 A / 0.045 A = 12 • Electron energy ratio: (10 GeV / 27.5 GeV)4 = 0.017 • ELIC / HERA radius: (0.18/1.0) = 0.18  1/R = 5.6 • Use of crab crossing makes this simpler for IR: • Confirmed (C. Montag) for old 100 mr crab crossing case • Detailed IR design needed

  24. IR Synchroton Estimates – Cont. 20s beam envelopes (green) and synchrotron radiation fans as generated by particles at 5s(red), horizontal (dispersive direction, x) to the left and vertical (y) to the right. The superconducting low-b magnets are indicated in blue. This study is for 10 GeV electrons, 100 mr crab crossing angle, and 6m detector space. Current Design: crab crossing angle: 22mr, detector space: 8m Alex Bogacz, Slava Derbenev, Lia Merminga (JLab) and Christoph Montag (BNL)

  25. Summary and • A lot of work a head of us to come to from a detector sketch to a detector design • simulate golden physics channels in a detector frame • start generic detector R&D • PID: High resolution / high rate ToF – systems • high resolution  10 ps Cerenkov radiators compined with modern light sensors MCP-PMT, APD’s, SiPMT’s, HPD • high rate  30ps – 80ps MRPCs 30kHz/cm2 • Calorimetry: • W-Si electromagnetic calorimeter g/ p0 separation • Hybrid (StriPads) sensors with single- or double-sided readout • Developing Methods to tag Coherent Diffraction in e+A • Design Roman Pot stations, which would fit between DX-D0 magnets @ current RHIC  measure in UPCs DIS – Madrid, April 2009

  26. Backup DIS – Madrid, April 2009

  27. Lambertson Magnet Design Cross section of quad with beam passing through Magnetic field in cold yoke around electron pass. Paul Brindza

  28. How should the detector look like • General requirements independent of EIC machine option • cover a wide range in Q2  detect scattered lepton • ep and eA need good lepton-hadron separation • needed over a wide momentum range E.C. Aschenauer

  29. Crab Crossing • High repetition rate requires crab crossing to avoid parasitic beam-beam interaction • Crab cavities needed to restore head-on collision & avoid luminosity reduction • Minimizing crossing angle reduces crab cavity challenges & required R&D State-of-art: KEKB Squashed cell@TM110 Mode Crossing angle = 2 x 11 mrad Vkick=1.4 MV, Esp= 21 MV/m

  30. dp/p angular dependence p = 50 GeV p = 5 GeV Can improve resolution at forward angles by offsetting IP

  31. Multiple scattering contribution p = 50 GeV p = 5 GeV Multiple scattering contribution dominant at small angles (due to BT term in denominator) and small momenta

  32. Mon Dec 01 12:30:09 2008 OptiM - MAIN: - N:\bogacz\Pelican\IR_ion_LR.opt Mon Dec 01 12:26:08 2008 OptiM - MAIN: - N:\bogacz\Pelican\IR_ion_LR.opt 2 2 5 12000 bmax ~ 9 km bmax ~ 9 km Size_X[cm] Size_Y[cm] BETA_X&Y[m] DISP_X&Y[m] b┴* = 5mm b┴* = 5mm s* = 14mm f ~ 7 m f ~ 7 m 0 0 0 0 0 Ax_bet Ay_bet Ax_disp Ay_disp 31.22 0 BETA_X BETA_Y DISP_X DISP_Y 31.22 8 m 8 m Interaction Region: Simple Optics • Beta functions • Beam envelopes (σRMS) for εN = 0.2 mm mrad s* = 14mm • Triplet based IR Optics • first FF quad 4 m from the IP • typical quad gradients ~ 12 Tesla/m for 5 GeV/c protons • beam size at FF quads, σRMS ~ 1.6 cm

  33. Crab cavity development (~22 mrad crossing angle for 10 GeV electrons and 250 GeV ions) Electron: 1.2 MV – within state of art (KEK, single Cell, 1.8 MV) Ion: 24 MV (Integrated B field on axis 180G/4m) Crab Crossing R&D program Understand gradient limit and packing factor Multi-cell SRF crab cavity design capable for high current operation. Phase and amplitude stability requirements Beam dynamics study with crab crossing ELIC R&D: Crab Crossing

  34. H(e,e’π+)n – Electron & Pion Kinematics Tanja Horn Ep=50 GeV Ee=5 GeV P (GeV) Pion Lab Angle (deg) • Most electrons scatter at angles <25°, but Q2 > 1 GeV2 restricts to > 10° • More forward angles correspond to (very) low Q2 • Most electrons have few-10 GeV momentum • Most pions electroproduced at forward angles > 140 degrees, even more forward for higher ion beam energies • Pions in “central” region, 25 – 140 degrees also have momentum of few-10 GeV Electron Lab Angle (deg)

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