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Detector Considerations @EIC. Rolf Ent, eA Meeting @ BNL, 05/07/05. Here, we will only discuss a multi-purpose high-luminosity ep detector, not a dedicated lower-luminosity ep/eA detector as suggested by Allen Caldwell et al.
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Detector Considerations @EIC Rolf Ent, eA Meeting @ BNL, 05/07/05 Here, we will only discuss a multi-purpose high-luminosity ep detector, not a dedicated lower-luminosity ep/eA detector as suggested by Allen Caldwell et al. At present, potential high-luminosity eA studies have not been integrated into these considerations yet, we hope to start the MC simulations for eA after this meeting. The following slides are only a working document for discussions, they are the “summary” of the last EIC Monte Carlo Group meeting, presently only drafted by Antje, Abhay, and me. • Open Charm Production/Glue • Electron Detection/DIS for ep and eA • Flavor Decomposition (+ DES) • Questions/To Do
Detector Considerations @EIC • Open Charm Production: • Dominant reaction mechanism through glue at small x e/ion momentum mismatch not so relevant and created nearly at rest Decay products at large angles. Need to determine angle range. • Background reduction critical issue requires <100 m vertex resolution drives vertex detector • Decay products have typical momenta between 0-2 GeV Need good particle id in this region and good track capability in large rate region GEM layers as TPC would work, use dE/dx plus TOF of hodoscope (with 100 ps timing resolution, 3.2 meters gives 3s p/K separation) • HERA typical momentum cutoff of 5 GeV, studies show can push down to ~Field (in Tesla) of Solenoid. STAR has only 0.5 T field and lower cut-off of 0.4 GeV Need low T (about 0.5) magnetic field in central region.
Open Charm Production @EIC (Antje Bruell, EIC MC Group Meeting @ Boulder, Nov. 04) Example of vertex displacement for charm (D0) events Black curve: divided by pD to cross check life time ok Large rate at small vertex separation good vertex separation enhances rate vs. background 100 mm
Open Charm Production @EIC - II (Antje Bruell, EIC MC Group Meeting @ Boulder, Nov. 04) PYTHIA – hadronic D0 decays Need both Particle Id. and vertex detection (preliminary) Charm counts from AROMA ~ Charm counts from PYTHIA(as cross check)
Open Charm Production @EIC - III (Antje Bruell, EIC MC Group Meeting @ Boulder, Nov. 04) AROMA – kinematics of decay particles (p+ and K-) from charm events
Detector Considerations @EIC - II • Electron Detection: • Do we need momentum determination through magnetic field or can one simply use this to determine charge-sign and rely on high-resolution calorimetry (PbWO4?). Needs to be determined from simple kinematic arguments and (as quantitative example) from QCD analysis. • A solenoid has implications for the highest luminosity one can reach in the IR, as it acts as a (de-)focusing element for the electrons/ions. Could one use a torus instead? For a solenoid, the lower the field (0.5T?) the better, + should we only cover the IR of relevance (10-30 cm?). In general: reduce ∫B.dl along beam axis. • How can we accomplish small angle electron scattering? Is placing E.M. calorimeters all around the ring o.k., like in the Muon/g-2 ring? What x-Q2 resolution/coverage?
Detector Considerations @EIC - III • Flavor Decomposition: • Need comfortable z cut (> 0.2?, +pT cut?) for reliable flavor decomposition This gives pions/kaons of a few GeV or higher. What pion/kaon momenta range? • Probably do need reasonable momentum resolution and charge-sign determination is a larger field (solenoid or other) needed outside the central region? What resolution is needed? • DES processes likely drive hadron resolutions required. • Analysis with purity matrices should show to what extent p/K identification is a requirement (note that it is likely that DES processes drive the p/K requirements). • Urgently need momentum/angle distributions of particles associated with physics processes of interest!!!
Detector Considerations @EIC - Questions • Can one get away with a small length inner vertex detector to only cover the bunch crossing? • Does one need a composite field structure (~0.5T in inner region, step function more radially out? ~PHENIX). • Is PbWO4 and a 0.5 T solenoid field sufficient for electron resolutions? Could we use a toroidal field? • What momentum resolutions are required for few-GeV/c pions/kaons? What field would be needed for this? • Is a gap in p/K identification acceptable for the intermediate hadron momenta (2-5? GeV/c)? • Are EM calorimeters all around the ring sufficient for very-small angle electron detection? • What are the implications of a 100 mr crossing angle? (relevant for ELIC only)