Dear Pierre and Reinhard,

Thanks for looking over our proposal. We thought that it might be helpful
to your review if we comment directly on the TAC and the Theory reports. We 
have listed them below for your review.

TAC report
----------
Comment 1:
The first comment emphasizes the long-time experience of our collaboration
with "the measurement of L-T separated forward meson production in Hall C". 
It is pointed out that as for any experiment using the SHMS "new calibration 
procedures will need to be developed for commissioning". This will undoubtedly 
be a combined effort between our collaboration, Hall C staff and users at the 
time when the SHMS is brought on-line.


Comment 2:
The second comment addresses the suitability of the SHMS for this experiment.
It is concluded that "angle and momentum ranges in Table I of the proposal are
consistent with the HMS-SHMS angle and momentum ranges".


Comment 3 and comment 4:
"This program requires 8cm and 4cm LH2 cells with minimum density changes with 
a rastered 90uA beam. The existing 4 cm tuna-can cell design performs well
provided the beam is properly centered. A suitable 8cm cell may need to be 
developed by the target group. The collaboration should consider using a 10 cm
cell, one of the planned standard target lengths."

"In the early years of 12 GeV operation, the practical limit on the beam
current for 11 GeV running will be 75uA. The use of longer target cells may
compensate for this limitation."

The most recent statement from Hall C management was that one may assume that 
beam currents up to 90 uA would be available when making beam time
estimates. We thank the reviewer for making this very useful suggestion
about the practical limit on the beam currents during early running at
12 GeV. This would allow the experiment to be performed with a maximum
beam current of only 75uA, instead of the 90uA previously assumed. 

Lowering the beam current would clearly result in a longer running 
time, though not necessarily for all of the data. If these targets were
not available, it may be possible to run with a slightly longer target, e.g.
the standard 10-cm cryogenic target, which would compensate for the lower
beam currents. However, the resulting difference in acceptance has to
be evaluated carefully, so that the systematic uncertainty does not
increase significantly.

Comment 5:
"The proponents argue on the one hand that this experiment is a logical
candidate for early running because it is not as systematics limited as L/T
studies in (e,e'pi^+). But on the other hand, they have only asked for 4 days 
for calibrations. If this experiment runs earlier, it may need more time for
calibrations."

Our assumption is that part of the commissioning/calibration time, for instance
calibrations that are needed for general operations will be allocated by 
Hall C management when this new device will be brought on-line.


Comment 6:
"As the proponents point out, full pi^+/K^+/p separation can be complicated at
these energies. A run-by-run plan for PID should be a high point of every 
readiness review. In addition, to the heavy gas Cerenkov for which one of the
co-spokespersons has taken responsibility, several aerogel detectors need to
be funded and built."

Four sets of aerogel would provide reliable K^+/p separation over the full
momentum range of our experiment (2.6-7.1 GeV/c). A recent statement by Hall C
management was that one may assume that funding and building of aerogel 
detectors will be available as part of 12 GeV operations. In addition, the 
Mississippi state group, which is part of our collaboration, has taken 
responsibility for building a threshold aerogel detector. However, alternate 
PID methods (such as a RICH detector) could also be employed.



Comment 7:
"About half the requested running time is at non-standard energies. Thus single hall running may be required for those portions of the experiment."

The standard 12 GeV energies are 2.2, 4.4, 6.6, 8.8, and 10.9 GeV. The proposed
experiment requires additional energies for the proposed L/T separations. 
However, the additional energies can be achieved with only three non-standard 
linac gradients. This selection of linac gradients represents one feasible 
solution, but others may also be acceptable. The linac gradients which would 
be ultimately used will depend to some extent on scheduling constraints.

The need for non-standard energies for our experiment is also explained in 
the first part of technical comment #8 shown below.

Comment 8:
"The large number of beam energies is surprisingly well-motivated. This 
proposal consists of three parts which could have easily resulted in 3 separate
proposals. In addition, each L/T separation at fixed Q^2 requires at least 
two beam energies, and minimizing the error in L/T separations generally
requires non-standard energies. Considerable flexibility in scheduling will
be required. As for the collaboration, they will have to become very good at
remembering to reconfigure the particle identification detectors in the SHMS
with almost every significant momentum change."

We fully agree with this very helpful comment. The runplan will clearly have
to be structured very carefully to ensure that these particle identification
reconfigurations are done with the great care and diligence.



THEORY COMMENTS:
----------------

As stated in the theory review of our proposal, one of the main goals in our 
proposal is to "study the pseudoscalar meson production mechanism, in 
particular the t-channel kaon exchange in the amplitude by measuring dsigL/dt 
and its t-dependence for several values of Q^2 above the resonance region". 
This is of particular importance, since there are practically no high precision
L/T separated kaon data available above the nucleon resonance region as 
illustrated in Figure 1 (kaon_sigl_sigt_project.eps). Our data will cover a 
region where the relative longitudinal and transverse cross sections have not 
been measured and predictions have large theoretical uncertainties as 
illustrated in Figure 2 (kaon_lt_ratio_project.eps).

These data will be used to determine the relative contribution of the K and 
K* exchange to the longitudinal cross section. If the K exchange is indeed 
found to be dominant, we would use the data to extract the kaon form factor. 
However, as stressed in the theory report, "the results of this experiment 
would be no less interesting if non-pole contributions to the amplitude turned 
out to be substantial".

The second goal of our proposal is "the planned high Q^2 measurements [which] 
are also very interesting, allowing for a quasi-model independent comparison 
of kaon and pion production in the scaling regime, which is more robust than 
calculations of absolute cross sections based on QCD factorization and present 
GPD models".

 
If you have any further questions, please do not hesitate to contact us.

Sincerely,
Tanja Horn, Garth Huber, and Pete Markowitz