PLANNING FOR JAPANESE PARTICIPATION IN ALMA
                         R. L. Brown (12 May 2000)

1.  As we discussed at the last ASAC teleconference, the Japanese plans
to become a third, equal, partner in ALMA are maturing at such a rate
that the ACC has requested the AEC (Kurz, Guilloteau, Brown and Rafal)
to develop plans for an "enhanced" ALMA that includes Japan as a
partner.  The plan should be done on the basis of potential science
return, and to this end the AEC asks the ASAC to help.  Specifically, we
seek ASAC input in the form of a concise draft that prioritizes
enhancements to the baseline ALMA seen as desirable by the ASAC.  The
draft (or the ideas to be in it) would be most useful if it were
available by Friday June 23; this is a few days in advance of the time
the AEC will meet with the Japanese group.

2.  As input to the ASAC discussion I have attached a pdf file of the
final report of the "ALMA Liason Group".  This was given to the ACC at
their April 2000 meeting.  It summarizes a range of ideas presented by
the Japanese group for possible ALMA enhancements.  Ignore the
references in this document to 'enhanced' and 'baseline' options.  For
those who have difficulty dealing with attachments, the file can be
accessed at

http://www.cv.nrao.edu/~cwhite/almaus/algreport.2000may12.pdf

3.  In short, the goal is to discuss the makeup of a $552M+$552/2M =
$828M ALMA, where the costs, or "value", of the parts are determined
from the costing done for the US-European "baseline" project.  What
should be added to the $552M Project for greatest scientific benefit?
[Don't worry at this point as to which partner would be responsible for
delivering which specific instruments--the goal is to specify what is in
the $828M array].

4.  Many of you may want to work from costs.  Let's use these estimates
for consistency starting from the "baseline":

     Management                             $24.6M
     Site Development                        77.9
     Antennas                                    212.4
     Receiver Subsystem                      92.6
     LO Subsystem                              36.1
     Backend Subsystem                      32.9
     Correlator                                     16.9
     Computing Subsystem                   30.7
     System Engin & Integration            21.3
     Science Support                              7.0

              TOTAL                           $552.4M

Some of the additional money to be brought to the project by the
Japanese is spoken for.  In particular the site infrastructure will be
more extensive (+$30M?), the additional partner will have a 1/3 stake in
the management, which now includes management of the project in Japan
(+$12M?), System Engineering and Science will be more comprehensive
again owing to the effort in Japan (+$10M?), and there will be
additional backend hardware and perhaps a bigger correlator (+$15M).
Let's assume a total of $66M goes for these things combined; this leaves
us with something like $210M to add enhancements to the antenna and
receiver/LO system.

Now let's parameterize the Antenna and Receiver/LO costs so that we can
add (and subtract?) from the array:  If N_ant is the number of antennas
in the array, and N_bands is the number of receiver frequency bands
installed per antenna, let's use

     Antenna Cost = $20M + $3.0M*N_ant

     Receiver Cost = [$700k + $200k*N_bands]*N_ant

     LO Cost = [$200k + $100k*N_bands]*N_ant

This makes a fully equipped (10 frequency bands) antenna cost $6.9M
(including contingency, labor, materials, shipping,
installation.....everything).

5.  One of the possible enhancements to ALMA is an array of antennas of
diameter smaller than 12m to be used to measure source visibility
accurately on spacings ~10-15m that are not well sampled by the
homogeneous array.  If this idea is scientifically appealing, please
address the following questions:

     -What is the diameter of those antennas and on what criteria is
this choice made?
     -How many such antennas are desirable and on what criteria is this
choice made?
     -Are the antennas fixed or moveable?  (The ALG report speculates
about putting them on rails so that the small array can be tailored to
source declination--any value to this?)
     -Does the array of small antennas need to be correlated with the
array of 12m antennas?  (If so, the two arrays would have to be
co-located).
     -If the array of small antennas does NOT need to be correlated with
the array of 12m antennas then it can be located apart from the 12m
array, and in particular it can be placed on a higher site, ~5300m, yet
still in the Chajnantor science preserve.  Any science value in this and
the opportunity to observe at >1 THz it maximizes?

To estimate the costs assume that the small antennas and their
electronics have exactly the same costs as those for the 12m antennas
given above (lessened economies of scale).

6.  For those possible enhancements that overlap with tasks already part
of the project (e.g. cryogenic systems, SIS fabricaton) it is enough to
prioritize the contribution, we'll give it the same "value" as the same
work done in the US or Europe.

7.  For those tasks still ill-defined (e.g. the FX correlator and the
photonics systems) it is again enough to prioritize the potential
science benefit; we can work out the value to be assigned later.