**Comments on NuMI horn transmission line Review Feb. 26, 2002**

**From Frank Nezrick, March 7, 2002**

1\. Overall Remarks

At every NuMI horn system review I have attended, I have been impressed
with the quantity and quality of the design and engineering effort
invested. This review has been no exception. Such thorough work will
certainly lead to a reliable, long lived focusing system. My primary
concerns lie with the need and reliability of the Flex Joint, and the
dearth of testing time for the final horn system before taking beam.

2\. Itemized suggestions, questions and concerns

\(1\) Flex Joint

I again state that I seriously question the need of the flex joint for
Horn 1. Since the transverse position of Horn 1 most likely will not be
scanned to verify beam centering, I do not see a justification for the
flex joint. It adds extra cost, effort (time) and complexity.

The present joint allows some flexibility, albeit at a much smaller
level, due to this concern. It is no long a complicated design and
allows flexibility simply by having narrower strips of aluminum and
appropriate spacing of joints. (see
<http://www-numi.fnal.gov/numwork/tdh/tdh_index.html>, Section 4.3.5).

\(2\) Flex Joint

In the note of Zhijing Tang of October 2001 concerning the Finite
Element Analysis of the flex joint, he notes the importance of keeping
the slots at each bend to an equal length (also noted in Nancy\'s talk).
Also if I understand the calculation correctly the slots lengths are
always symmetric wrt the center of curvature for each bend of the
transmission line, e.g. Figs 4, 10-14. This implies drawings on page 1,
4, 5 and 9 of the Drawing Package handout by Boettinger are incorrect.

The horn joint designs have been changed and no longer include slits.
(see <http://www-numi.fnal.gov/numwork/tdh/tdh_index.html>, Section
4.3.5)

\(3\) Flex Joint

It is planned that the prototype flex joint and remote clamp will be
pulse tested at MI8. It is essential that the prototype survive the
testing. However we should require more. The testing plan lacks
quantitative measurements (deflection at specific points, resonant
frequencies, etc.), which might demonstrate agreement with expectations
(ANSYS calculations, etc.) thus supporting an anticipated longevity.

Testing at MI8 has included some measurements of vibration & deflection.
This information has not yet been summarized and compared to ANSYS.

\(4\) Vibrations

The transmission lines in the target hall when pulsed will act like
xylophone bars; they will undergo transverse and longitudinal
vibrations. There is probably time and space to develop appropriate
dampening methods after the TL system is installed. However, vibrations
from the transmission lines and flex joints in and under the horn module
should be better understood soon so space, e.g. for dampers, might be
allowed in the module design. Hints might be obtained during the flex
joint testing program at MI8.

The joints tested at MI8 are the ones that will go in the Target Hall.
The spacing of the clamps at MI8 is quite similar to the Target Hall
spacing. Measurements of deflection and vibration have been made at MI8
and as a result we are not concerned. These results need to be written
up.

\(5\) Nancy listed on Pg. 21 of her handout a Concern: \"Schedule is a
bit tight.\" In the part of the installation schedule not shown on Pg.
20, but discussed at the review, it appeared that the amount of time
allowed for testing (pulsing) the horn system in its running position
was about one month. If no failures or major modifications are
encountered, a month may be sufficient. My concern is that for various
reasons this testing time might be reduced even more. It should be
remembered this will be the first time the horn system will be operated
in this configuration (supported from actual module with all appropriate
motion controls and monitors installed, target installed, target hall
transmission line attached, etc., etc.). Proper testing time must be
rigidly scheduled, even if only 3rd shift.

We will do the best we can in this area.

**Comments on NuMI horn transmission line Review**

**Feb 26, 2002**

**From Dave Pushka**

1\. Overall Remarks

Appropriate engineering issues have been / are being addressed in a
prioritized manner. Progress appears to be satisfactory.

Decision to use a single lead engineer will reduce the potential for
interferences or omissions of scope. It does result in longer
engineering design duration than it would if a good team could be
assembled, but previous attempts to assemble a team have not been
successful. The impact on the longer duration needed to remain under
continuous management evaluation. Continuous management evaluation by
the level 3 system manager is underway, hands on, and effective.

2\. Itemized suggestions, questions and concerns

\(1\) Resources are just barely enough to pull off this work. Key areas
where more help could be efficiently used is for drafting and will
eventually include technicians for stripline assembly. Project
management for NuMI needs to bring to the attention of the Beams
Division management and relevant department heads the presently foreseen
technician shortage during the MiniBooNE installation and the NuMI work
so that they can react in sufficient time to borrow additional help from
other areas of the laboratory.

We have done and will continue to do the best we can in this area.

\(2\) While the following comment is outside the presently budgeted
scope of work and will require a large effort to pull off, the full
production stripline and power supply and horns one and two should be
assembled in MI 8 after MiniBooNE clears out as a full scale assembly
test. The full system will need to be assembled eventually. Current plan
is to assemble it underground and this work is likely to be on the
critical path (or near enough to it the any problems in the stripline
assembly will put CD-4 in jeopardy). By starting the assembly earlier
and in a service building, problems can be solved without affecting the
critical path. This is more work because some effort will need to be
duplicated, but if we are serious about reducing the length of the
technical component installation, this is a wise and prudent addition.

We will do some level of assembly at MI-8 -- whatever seems to make
sense given the time and resources.

**Comments on NuMI horn transmission line Review**

**Feb 26, 2002**

**from Jim Kilmer**

1\. Overall Remarks

The design seems to be coming along fine. I didn\'t see any problems
with the mechanical aspects of it or any fabrication problems.

2\. Itemized suggestions, questions and concerns

\(1\) I\'m concerned about the level of drafting supplied to this task.
It\'s not clear to me that the team can keep it\'s schedule without more
drafting help. I would encourage the NuMI management to try and get some
more help from the PPD/MD for this.

This has been a constant problem with the entire NuMI Project -
insufficient drafting help -- resulting in much longer than anticipated
time to complete drafting. This, unfortunately, continues to be a
problem. The Project continues to work on improving this situation, or
at least stopping it from getting worse.