Present: Cooper, Grillo, Jaros, Maruyama, Nelson, Partridge

Next meeting will be the coming Friday, Feb 19.

Hopefully we can get info on the resolutions for the two possible readout chips from simulation. Alex will present what's needed for the ABCD readout chain.

1. Background.
After our trip to Jlab, we have decided to concentrate on a dedicated experiment (vs parasitic),which would be located at the end of the Hall B site, in what they call the alcove. This location has much more space available, will allow much better access to the apparatus, and can accommodate a large H magnet, 2T, 1m long, somewhat larger gap (or better field quality in the same gap). In contrast to the parasitic design, bends will be horizontal, so the wall of fire (radiative events from the target), will be horizontal. A better estimate of transverse dimensions is coming. We're debating if the analyzing magnet is the first or second of the chicane.

Homework: New baseline design (Takashi and John)

2. Pattern Recognition Studies.
Rich reviewed Matt's slides, attached above. Good news is that even our simple 4 bend plane, 3 non-bend plane sensor layers will pattern recognize with backgrounds present as long as the experiment is in vacuum. Occupancies and resulting ghosts are problematical in air. This confirms early work from Takashi emphasizing the need for vacuum (or perhaps He).

Homework: The simulation should be done with a more realistic thickness. Bill ventured that 1% X0 should cover two sensors and support material. All cooling is relagated to sensor edges far from the active area.

While fake rates are reasonably low, it will be necessary to understand the tails to the impact parameter distributions in some detail to assure that backgrounds can be efficiently rejected. See the study of vertexing efficiencies attached above, which uses several new ideas to suppress mis-measured vertices. The present work assumes perfect pattern recognition, but does include the full effects of Moliere scattering and electron radiation in passing through the sensors. The full effects of pattern recognition mistakes must be understood, mitigated if possible, and added to the present study.

3. Mechanical Layout
Bill discussed possible sensor layouts, with a design attached above. He imagines silicon sensors on both sides of of a CF Rohrcell CF  sandwich. Cooling tubes are at outer edges only. For sensors whose long edge is perpendicular to the gap, it is possible to overlap sensors. For sensors whose short edge is perpendicular to the gap, full overlaps would require both horizontal and vertical overlapping, which is awkward. Bill therefore assumes that sensors are overlapped in one direction, but not in the other, and leaves a 0.5 mm gap between sensors. This will create 2.5mm dead zones between sensors. A problem?

Homework: The impact on the acceptance must be evaluated.

Homework: How many sensors are needed in each of the layers to capture all the acceptance?

We discussed adding stereo or pixel information to add space points to found tracks, in the attempt to eliminate ambiguities. It was argued that the pixel info provided by the ecal was too coarse grained to help.

Homework: Where should stereo layers be introduced to remove ambiguitites? How many stereo layers are needed? Are any AtLAS pixels available?

4. Further comparisons of APV25 and ABCD
Tim's talk is attached above. He considered the effects of radiation on the sensors, and the ability of the two readout chips to accommodate sensor degradation. Tim has been readying new simulation code appropriate to studying the two possible readout chips on the sensors we have. He will work with Matt to apply this code to nominal performance and to rad damaged performance.

The issue of radiation damage for the readout chips was raised. We imagine locating the readouts far from the beam and out of harm's way, but need to estimate the dose they will receive.

Homework: What is rad dose on readout chips?