MDI meeting minutes
Attended: P. Burrows, P. Bambade, T. Tauchi, Deepa, K. Buesser,
W. Lohman, A. Seryi, T. Markiewicz, Lu?, Y. Sugimoto, W. Kozanecki,
T. Omori

1. Beijing MDI sessions and plenary speakers

a. Joint opening session MDI talk - A. Seryi
b. Physics/detector part MDI summary talk - T. Tauchi

Also, we will ask for two sessions ( 4 hours each ).
We need to cover the push-pull issues, LEP issues,
beam background issues, and topics more directly related
to machine also. The time of the sessions needs to be
coordinated with GDE.

2. Push-pull option

First, HY explained the current status of the push-pull discussion
process: After Valencia, each concepts were asked by WWS to submit
a statement on push-pull. WWS co-chairs and representatives of
concepts had a phone conference on Nov 22 to discuss the contents
of the draft statements, and subsquently WWS drafted a cover letter
based on the discussion with the concepts. WWS is about to sent the
concept statements and the cover letter to CCB.

The presentation files are at

Then Toshiaki presented the GLD statement (please see the file
online). In short, GLD thinks that no convincing proof
has been presented for push-pull to work, and it would like
the decision on push-pull to be postponed.

HY explained WWS cover letter has no 'recommendation' on push-pull,
rather it simply expresses concerns. TM suggested that WWS should
make certain recommendation after unifying opinions. HY replied that
WWS's letter has been approved by WWS, and it would be difficult to
change the process at this time, but the MDI panel can make such

Then, KB has presented the LDC statement which was preliminary but
close to the final. The statement was similar to that of GLD.
KB said that the technical problem of fast switching of 2 IRs had
not been well communicated to physics community. TO said in two
IR scheme fast switching of 2 IRs is possible in currently available technology if fast means every 5-10 minutes. The general agreement was
that there has been some discussion on fast switching between
2 IRs going back to Snowmass, but no in-depth discussions have been
done so far. WK commented that it is too late for such discussion
at this time.

Then, Phil Burrows presented SiD position by slides. (please
see the file online) SiD is in agreement with other concepts
in that SiD thinks the ideal situation is where 2 detectors
at 2 IRs sharing luminosity equally. SiD also thinks that there
are many unanswered questions on push-pull, but more optimistic
in thinking that those problems could be solved with enough
efforts and resources.

Then, HY presented WWS's cover letter (please see the file online).
In summary, WWS thinks having no show stopper for the push-pull
option is not enough to risk losing 2 detector option. Also,
it expresses a concern that the push-pull is already included
in the IWA for future cost estimations.

TM points out that what is read out of the statements of
WWS and concepts seem to be different from the
report by the parameter committee. HY explains that the
parameter committee is not under WWS, but under ILCSC; thus,
WWS and the parameter committee are essentially not the same,
even though it would be better if they agree.

AS stated that in the WWS's 'the answer to the question
"is there a possibility that the push-pull option will prove
unfeasible?" is probably yes.', 'push-pull' should be
'fast push-pull'. HY explained that 'feasible' may be too
technical, and what is meant is more political.
Bambade suggested the word 'inpractical', instead.

HY said that there was some difference in temperature
between the physics community and the GDE management based
on availability of cost information, and that if
that cost pressure can be shared, the physics community
may accept the push-pull option.

AS asked if an internal alignment system of detector is needed
regardless is needed push-pull or not. The answer
was yes, but requirements are stronger for push-pull.

AS also asked if the credibility of the push-pull option is just
as good as the other detector design. KB and HY disagreed; the push-
pull design is not at the save level as the design of the detectors
in general which also have options alive.

HY proposed a meeting of GDE, WWS co-chairs, and concept
reps to smooth out the temperature difference. It was, however,
turned down due to lack of time before the SLAC meeting.

Burrows asked if it is possible to add the 2nd IR if the push-pull
proves not viable. The general agreement was that the baseline
should include a possibility of 2 IR upgrade. Politically,
it would be difficult to move back to 2 IRs later, but in
some cases where the future host or other funding countries
may tell us to build the 2nd IR presumably before the start
of construction. One could leave enough space/length in the
BDS beamline so that 2nd IR can be added later. RDR could
include the 2 IR design as an option with costing at a rougher
level than the baseline. Burrows pointed out that we should
be careful not to let the detector community feel that the 2 IR
option is effectively dead, like the gamma-gamma option.

AS asked how to ensure detector people's involvement
on the push-pull study. The push-pull task force needs a new
charge to continue its work, which WWS and GDE should issue.

It was agreed that HY would draft a MDI statement on push-pull.
We will work on it online.

Burrows commented that there should be some coordination
that concepts can give inputs to CFS on costing, in particular,
which items are to be included in the detector cost and
which in the machine cost, such as the number and capacity of
the underground cranes.

The MDI panel had a meeting on Dec. 8 and discussed the push-pull option.
There were reports from the three concept studies and the WWS about their
respective statements.

In general there was grave concern about the risk of losing the 2-detector
scenario in its entirety. There was also concern that the push-pull option for
2 detectors at a single IR has not been investigated sufficiently thoroughly to
allow a sound technical basis for its acceptance as the baseline.

The fact that the primary motivation for the push-pull model is to save on the
cost of the accelerator has caused considerable misunderstanding within the
detector community, which does not enjoy the same level of cost-consciousness
as the GDE. We thus suggest that there be efforts both by GDE and WWS/Concepts
to share and communicate the overall cost reduction strategy, possible trade-offs,
and its implementation.

Regarding CCR#23, we recommend that, if the push-pull option be included
as the baseline, then the 2 IR option be also explicitly included in RDR as
an 'alternative configuration', with a cost estimate. We understand that such a
cost estimate may, by necessity, be less complete than the baseline cost.
In addition, provisions should be included in the baseline design to facilitate
a change to the 2 IR design in the event of either:

a) the push-pull model proving unfeasible, or
b) additional funding being secured for a second BDS and IR.

Finally, we urge the GDE and the WWS to give a new charge to the
push-pull task force to continue the study of the technical implementation
of the push-pull option.