MDI panel meeting
Oct 24 2006, minutes

Attended: Seryi, Busser, Markiewicz, Omori, Lohmann,
Kozanecki, Bambade, Burrow, Torrence, Yamamoto, Deepa

1. CERN LHC-ILC engineering forum report
Report had been circulated to the MDI panel members
prior to the meeting. There were additional comments/
discussions during the meeting.

The impression was that ATLAS also wanted to adopt
a surface assembly if their magnet design (toroid)
allowed. The surface assembly is more relaxed and
more safe.

* Airpad
The compressor is not large. The size and cost is not
an issue.

* Service cavarn
A general impression is that in general, there are
more space need than we had assumed. Also, a place to
put equipment that is sensitive to radiation and
magnetic field is needed. We need to make sure that
whatever our design is, it should have enough space
for such equipments. Witold points out that most
equipments that have motors need to be put in a
magnetic-field-free place. CMS has a galleries
almost touching the return yoke on both sides
where equipments that does not suffer from magnetic
field are placed (power supplies and some FEs).
We need some study on the issue of magnetic field
effects on equipments and storage space.

* space below the exp. hall floor
CMS has a quite large space below the exp. hall
floor which is fully utilized. For our case,
the space may not be large since we may have to
move the detector pieces all over the place.
(CMS moves along the beamline only)

* survey tunnel
LHC had survey tunnel for the final focuses.
For ILC, final focuses are inside the exp.
hall. We may need different survey system.

* push-pull
CERN engineers did not have much information on this.
We need to work on it, and that is why we have
the push-pull task force.

*** Now we should make good use of these information
in our design of the detector assembly and the
experimental hall. In particular, we should be careful
about the space needs - can we really do away with
service cavarn, separate service shaft, etc.?

2. push-pull task force
Many of the questions in the list have been already
answered. Concepts will be asked to answer remaining
questions. The next push-pull meeting is later next

3. MDI sessions at Valencia
1 session is dedicated to the push-pull issue, and another
is dedicated to detector assembly and experimental hall
etc. These are endorsed by MDi panel (as well as GDE and
WWS). Also regular BDIR sessions are planned.

4. 1/2 number of bunch (1/2 luminosity)
HY reported that WWS has drafted a list of questions
and passed on to GDE. Here is the list:

I. The technical merits of the reduced number of bunches:
We understand there are several merits to the reduced
number of bunches. We would like to know how critical
they actually are. Are they something we do not have
solutions now which are solved by halving the number of
bunches? Could you indicate the level of current
difficulties? E.g. :
a. ECE in the dumping ring, extraction kicker, and multi-bunch
b. Positron source target
c. Other possible merits

II. The RF upgrade to recover the 'full luminosity'
a. Required hardwares
b. Amount of work needed to install them
c. Realistic upgrade schedule
d. Changes required elsewhere of the machine associated
with the upgrade
e. Cost needed for the upgrade, and how it compares to
installing the 'full RF' as the baseline from the start
d. Realistic scenario after the start of the baseline
machine when the upgrade is proposed, approved,
funded, and the upgrade work can begin.

What the community really wants to know is how can one recover from this
provisional descoping of ILC and how long it may take to do so after
the machine has started. We understand that it is difficult to answer
such questions but at least it would help to be able to respond to
some of the technical aspects listed above.

Also, WWS needs input from the MDI panel on the effect of the low-P
option's effects on beam backgrounds and beamstrahlung. Wolfgang will
draft a short report for WWS.

The low-P option is there for the nominal beam parameters also, and
1/2 luminosity is a serious down-scaling of the physics capacity of
ILC. The MDI panel can make 'recommendation' based on effects on
physics when it deals with the beam background, beam instrumentation,
energy biases etc.

5. CCRs related to MDI/BDS
* 14mrad+14mrad - approved
* reduced muon walls - approved
* surface assembly - waiting for WWS's reply
(HY will make sure it will happen soon)
* push-pull - task force is working on it
* Central DRs - it will probably approved
Affects BDS in the design of shafts, service tunnels.
Does not specifically affect the push-pull.