To participants interested in working on the particle flow issues.

We will meet in front of the conference center at 12:30 and go for lunch
probably to the Salad place on the upper side of the mall, and try to get
a bit more organized.

We envisage agreeing on a few priority items for study and planning how
to attack the particle flow issues in the medium term.

Apologies for the late notice partly due to network trouble.


regards,

Felix, Mark, Steve, Graham

Minutes of Lunchtime Discussion
-------------------------------

At the LDC concept meeting on Wednesday it was suggested that
groups get together to get organized on particular global detector
concept issues.

One suggested focus was particle flow and
S. Magill, F. Sefkow, M.Thomson, H. Videau and G. Wilson
were volunteered to organize the work around this issue.

On Friday we had a lunchtime discussion which was advertized
by last minute E-mail to the LDC at Snowmass mailing list. Since
some participants are only here for the first week we believed that it
was important to meet and get started.
Apologies to interested participants who were probably not
aware of the meeting.

Minutes
-------
Present: N. Graf, M. Thomson, S. Magill, M. Ronan, G. Eigen,
F. Sefkow, P. Gay, G. Wilson, C. Hensel.

Mark presented a list of prioritized items about the overall
detector concept which impact the particle flow performance and
require studies.

We agreed to have a list of items which are perceived to be
of primary importance in the detector design in terms of
particle flow performance.
There was strong interest in trying to get together in a manner which
cuts across the SiD/LDC/GLD separate meetings.
How we can easily go about studying these items is reserved for
future meetings where we would develop a work plan.

Ideally we would be able to run several different PFAs over
different detector variations.
Some of these items may be addressed to some extent at Snowmass, others
are presumably studies that require more comprehensive work.

We will try and schedule a follow up meeting maybe on Monday.

Feedback about these lists and potential other areas of study
would be very much appreciated.
It would be great if you could also express your interest in
pursuing some of these issues.

Priority Items
--------------
1. B-field : is BR^2 the correct performance measure ?
2. ECAL radius
3. z ECAL endcap
4. Calorimeter total number of interaction lengths inside coil
(ECAL + HCAL) : do we need 4, 5, 6.. lambda_I ?
5. Longitudinal Segmentation. How much does the longitudinal
segmentation improve the ability to identify the particles in
the jets in pattern recognition terms,
rather than just being an issue about sampling frequency for
calorimetric energy resolution.
6. Transverse Segmentation.
7. Compactness / Gap-size.
8. HCAL Absorber choice: Stainless Steel, W, U, Pb etc.
9. Circular vs Octagonal TPC and circular vs polygonal ECAL:
how important are the gaps beteen TPC and ECAL
10. HCAL outside coil

Additional items perceived to be possibly of secondary importance
-----------------------------------------------------------------
(ie. if you are really interested in these items and you believe they
are of primary importance, then you are very welcome to
work on demonstrating that these things are of primary importance)

1. For events with missing energy, the forward part of the
detector may be very important for correct reconstruction.
This should be addressed by looking at jet energy resolution vs
polar angle. Detailed studies though depend quite a bit on the
actual accelerator design, and may not be that easy to pursue in
a general manner.
2. Detection thresholds for tracks, clusters.
3. Momentum resolution. What would happen if we back off substantially in
momentum resolution specs since these were not designed around particle
flow but from the recoil mass to the di-lepton in Zh events?
Method: degrade single-point resolution within the same
B, R**2 geometry.
4. How important is lepton id to the detection of semi-leptonic heavy
flavor decays (b, c) with neutrinos for jet energy resolution issues?
5. Particle ID. How much do we care about correct mass assignment
to charged particles, particularly protons in terms of PFA?
6. Are backgrounds from gamma-gamma and the machine important to the PFA and
are there detector design methods to mitigate these effects?
7. How important is 2-photon separation to particle flow, particularly after
applying pi0 mass constrained fits?
8. Is a tail-catcher important for spotting late interacting K0L and neutrons?
9. Could the DREAM approach work in the forward endcaps where the
tracking performace is starting to degrade?