Minute of the May 3 PEP-N meeting (post-workshop Summary of items that have been discusssed: 1) MACHINE : -Energy range -Dipole vs Solenoid -Polarization -Crossing Angle -B field 2)DETECTOR : -Background -Luminosity -Beam pipe -Simulation -Cost Evaluation -run plan -Sub-detectors -> TPC, tracking -> EM calorimeter -> Hodoscopes -> Aerogel -> Had. calorimeter 3) PLANNING FOR EPAC: -Management -Organization -Meetings Discussions: 1) **************** MACHINE ******************* Energy range: The maximum c.m. energy will be 3.1 GeV (J/psi peak), corresponding to a VLER energy of 780 MeV. The minimum c.m. energy should be around 1.2 GeV, which corresponds to a VLER energy of 115 MeV. We will try to go for a VLER energy range 100-800 MeV. Dipole/Solenoid: the option to have an axial solenoid instead of a dipole was briefly discussed; it seems to have some serious disadvantages: -Its impact on PEP-II is not negligible -It limits the acceptance In addition to that the detector design would be totally different. It was therefore decided to discard the solenoid option for the time being. Polarization: -We'll keep it as an option Crossing angle: -It would be nice to have a little crossing angle (few mrad) -Few mrad could be achieved as in PEP-II, without a major change in the machine design. B field: We will try to have a configuration with a fixed B field, which should be in the range 3-4 Kgauss. The needed field in the accelerator will then be achieved by means of an additional small dipole magnet and by adding/removing appropriate shielding on the beam pipes. This issue is thus coupled to the run plan, which should be optimized so that the change of shielding is not too frequent. Also, the effect of the additional dipole magnet on the acceptance and of the shielding on the B field in the TPC need to be studied. 2) **************** DETECTOR ******************** Background: The dominant source of background is most likely given by the lost beam particles. This issue is being studied by a group of people including L.Keller, M.Sullivan, P.Patteri and E.Pasqualucci. They expect to have some results in about a month. Luminosity: The luminosity measurement is being studied by M.Mandelkern and the UC/Irvine group. Some Monte Carlo studies will be carried out with bhabha, mu+ mu- and gamma-gamma events. Beam pipe: -Its dimensions have to be defined, based also on the foreseen background level. -An aluminum beam pipe, 1-2mm thick and 5cm to 10cm in diameter will work. -A berillium beam pipe was also proposed: it is trasparent to the syncrotron radiation, but is very expensive. Simulation: We will keep the general fast MC with parametrized resolutions. More detailed MC will be developed for some sub systems, if necessary (e.g. TPC). We should focus on the method of measuring R. M.Posocco and M.Negrini have written the existing Monte Carlo. One physicist from Novosibirsk will join the MC group in the summer. More people are needed in this area ! Cost Evaluation: M.Morandin is making a first cost estimate. Run Plan: -The dependence of the luminosity vs the energy has to be studied. -The energy steps and luminosity per step will then be decided accordingly. -A first coarse scan, followed by a more refined scan was proposed. Sub-systems: TPC -The TPC parameters seem to be defined and working fine. One issue to be looked at in some detail by means of MC simulation is the dependence of the TPC performance on azimuth. EM calorimeter -The thickness of the pole calorimeter can be increased from 10cm to 15 cm in order to improve the efficiency and the resolution. -The geometry will be studied by means of MC. Hodoscopes -They are needed for triggering purposes. It was suggested by the Ferrara group to use scintillating fibers to improve the tracking. Calabrese-Dalpiaz-Luppi will look into it. Tracking E.Solodov suggested to have additional tracking chambers surround the TPC. This could be achieved by means of drift chambers and/OR the scintillating fibers hodoscopes (see above). Aerogel -The design presented at the workshop seems to be fine. Its importance for the PID should be stressed in our next LOI. HAD. calorimenter/ Nbar-N detector The main issue here is whether to integrate the NNbar and R measurements into a single apparatus or to present two different configurations for the R and form factor measurements. It has being pointed out that nnbar capability would also be of importance for the R measurement, as the relative cross section contributes of the order of 2 % to e+e- --> hadrons. The options for the hadron/nnbar calorimeter are: - a MINOS-like calorimeter (as presented by D.Michael) - a Virginia-like detector (as presented by P.Bosted) - extension of the em calorimeter (based on the KLOE design) S.Rock and P.Bosted will look into these issues. cosmic veto -It was pointed out that we don't have any cosmic veto It was also said that the space between poles and chambers should be coordinated, V. Bidoli will take care of that. 3) ************* PLANNING FOR EPAC ************* Meetings: We will have regular meetings (in audio conference) to be held every two weeks. These are (tentatively) the next dates: May 14 (Mon.) 8:30 am SLAC time May 30 (Wed.) 8:30 am SLAC time Jun 11 (Mon.) 8:30 am SLAC time Jun 22 (Fri.) 8:30 am SLAC time Jul 9 (Mon.) 8:30 am SLAC time Jul 22 (Sun.) 8:30 am SLAC time Aug 6 (Mon.) 8:30 am SLAC time Aug 20 (Mon.) 8:30 am SLAC time Writing of the LOI: D.Bettoni and M.Mandelkern will circulate a proposal concerning the contents/chapters of the next LOI, to be discussed at one of the next meetings. A short summary (3-4 pages) of the LOI should also be written. Answer to the referee's questions: -Precision on R measurement -Priorities on physics -gamma-gamma physics -ISR in PEP-N The EPAC meeting will be on September 24. We need to find out what the deadline to submit the new LOI is. Collaboration organization: Spokesman: Diego Bettoni Coordinator for US: Mark Mandelkern Coordinator for Russia: Evgeni Solodov ********************************************* Wander & Gianluigi