1. Detector Considerations @EIC 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. Rolf Ent, eA Meeting @ BNL, 05/07/05 - Open Charm Production/Glue - Electron Detection/DIS for ep and eA - Flavor Decomposition (+ DES) - Questions/To Do

2. Open Charm Production: 1)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. 2)Background reduction critical issue  requires <100  vertex resolution  drives vertex detector 3)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 3  /K separation) 4)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. Detector Considerations @EIC

3. Open Charm Production @EIC (Antje Bruell, EIC MC Group Meeting @ Boulder, Nov. 04) Black curve: divided by p D to cross check life time  ok Large rate at small vertex separation  good vertex separation enhances rate vs. background Example of vertex displacement for charm (D 0 ) events 100  m

4. Open Charm Production @EIC - II PYTHIA – hadronic D 0 decays (Antje Bruell, EIC MC Group Meeting @ Boulder, Nov. 04) Need both Particle Id. and vertex detection (preliminary) Charm counts from AROMA ~ Charm counts from PYTHIA (as cross check)

5. Open Charm Production @EIC - III (Antje Bruell, EIC MC Group Meeting @ Boulder, Nov. 04) AROMA – kinematics of decay particles (  + and K - ) from charm events

6. Electron Detection: 1)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. 2)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. 3)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-Q 2 resolution/coverage? Detector Considerations @EIC - II

7. Flavor Decomposition: 1)Need comfortable z cut (> 0.2?, +p T cut?) for reliable flavor decomposition  This gives pions/kaons of a few GeV or higher. What pion/kaon momenta range? 2)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? 3)DES processes likely drive hadron resolutions required. 4)Analysis with purity matrices should show to what extent  /K identification is a requirement (note that it is likely that DES processes drive the  /K requirements). Urgently need momentum/angle distributions of particles associated with physics processes of interest!!! Detector Considerations @EIC - III

8. 1)Can one get away with a small length inner vertex detector to only cover the bunch crossing? 2)Does one need a composite field structure (~0.5T in inner region, step function more radially out? ~PHENIX). 3)Is PbWO4 and a 0.5 T solenoid field sufficient for electron resolutions? Could we use a toroidal field? 4)What momentum resolutions are required for few-GeV/c pions/kaons? What field would be needed for this? 5)Is a gap in  /K identification acceptable for the intermediate hadron momenta (2-5? GeV/c)? 6)Are EM calorimeters all around the ring sufficient for very-small angle electron detection? 7)What are the implications of a 100 mr crossing angle? (relevant for ELIC only) Detector Considerations @EIC - Questions