[asac] ASAC document

Mon Jun 12 10:46:01 EDT 2000

Dear Karl,

Regarding item 4 of the ASAC, I am sending separately (via Dr. Nakai) a draft 
of planning for an enhanced ALMA and the Japanese contribution for it.   I
hope it is not too late to be included in the 12th telecon.

Regards, Yasuo

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　　　　　　　       Plan for an Enhanced ALMA

　　　　　　　　　　　     12 June 2000
                   　Japanese members of ASAC

 Japan will participate in an enhanced ALMA project as an equal partner 
as the US and European sides by bearing 1/3rd of the project.  To realize
the project, we will ask the budgets of its design for FY2001 (which 
starts from 2001 April) to the government in 2000 June and of its 
construction for FY2002 to FY2008 in 2001 June.  Our plan is that 
construction of the Japanese portion finishs in FY2008, adjustments  
with the US and European portions are made in FY2009 and FY2010, and
full operation for astronomical observations starts in FY2010.  However
the detailed schedule will be decided under nagotiation with the US and
Europe and we keep in step with the other partners.

 Dr R.L.Brown asked ASAC prioritizing the plan of an enhanced ALMA on
May 12 to send a report to AEC until June 23.  According to this seeking,
we have made the following plan for the enhanced ALMA on the basis of 
science return and construction cost and present it here to ASAC for 
discussion.  Boundary conditions considered for the plan is

 .that the total cost or "value" of the enhanced ALMA is $552M/2 x 3 = 
  $828M, 
 .that the costs (values) of the parts follow the estimation and 
  equations in "PLANNING FOR JAPANESE PARTICIPATION IN ALMA" (R.L.Brown, 
  12 May 2000) for simplicity, except the second generation correlator 
  whose cost has been estimated by ourselves.

Since the cost of antennas is the biggest, its unit price influences the
total plan of the project largely.  When the cost of an antenna is fixed,
we would have to re-consider the plan.

Plan for an Enhanced ALMA

1) Antennas

 A number of 12-m antennas is 78. Each antenna should have enough 
 capability for submillimeter observations.

   Science merits: Sensitivity of the array is increased by increasing
   the number from 64.  

 A compact array of seven 6 - 8m antennas is added.  The value of a
 small antenna should be equal to that of a 12-m antenna.

   Science merits: Since the minimum anntena spacing becomes shorter to
   be 8 - 11m, capability of the array for extended sources is improved,
   especially for shorter wavelengths.

   Total cost of all antennas = $20M + $3.0M x (78 + 7)
        　  　　　　　　    　= $275M

   Japan will bear 1/3rd of the total number 85 of the antennas.

2) Receivers and LO 

 Bands 3, 6, 7, 9 which have been given first priority in ASAC in March
 are important.
 In addition to these bands, bands 8 and 10 are also important and should
 be given high priority.

   Science merits: (see attached appendix)
   .Band 8 includes important lines of CO(J=4-3;460GHz), CI(J-1-0;492GHz),
    CS(J=10-9; 489GHz) et al. and thus is useful for study of interstellar
    matter and to see the cores of star forming clouds and inner 10 AU of
    protoplanetary disks.
   .Band 10 includes extremely high excited lines such as CO(J=7-6;807GHz),
    HCO+(J=9-8;802GHz,J=10-9;892GHz), HCN(J=9-8;797GHz,J=10-9;885GHz) 
    which are good tracers of high temperature and high density gas, and
    CI(J=2-1;809GHz). The band could detect redshifted strong CII from 
    galaxies at z = 1.1 - 1.4. In addition, the band is useful to observe
    strong thermal emission from heated dusts which is quite important 
    and useful to observe galactic regions of star and planet formation 
    and external galaxies.  
   .By increasing the number of receiver bands to be six, many excited
    lines of same molecules are observable, contributing accurate 
    determination of physical and chemical states of galactic and 
    extragalactic molecular clouds.

   Total cost of receivers = [$700k + $200k x 6] x (78 + 7)
          　　　　      　 = $161.5M

   Total cost of LO system = [$200k + $100k x 6] x (78 + 7)
          　　　　　       = $68.0M

   Japan will bear two of the six bands. Since band 10 needs technical
   development of THz SIS heterodyne reveivers, Japan may take charge of
   the band.

3) Correlator

 NRAO will construct the first correlator which can correlate signals from
 32 antennas.
 In addition to the correlator, Japan and Europe, collaborating each other,
 will develope and construct the second generation correlator which can
 correlate 125 kch/IF of signals from all the antennas 85.

   Science merits: 
   .The second generation correlator can treat all the antennas.
   .The correlator can improve the sensitivity by corresponding to multi-
    bits of the A/D converters.
   .Its high capability for spectroscopy can observe many spectral lines
    in the broad frequency band simultaneously.
   .Such high spectral capability may make serendipitous discoveries which
    open new world in astronomy.

   Cost of the first correlator (filter+XF,32 anntennas,2GHzx8IF,4kch/IF)
　　　   = $7M  (from correlator PDR)

   Cost of the second generation correlator 
                               (FX,85 antennas,4GHzx4IF,125kch/IF)
　　　   = $44M

  (Cost of A/D converters will be included in the following Backend 
   Subsystem)

4) Others

 According to the suggestion in "PLANNING FOR JAPANESE PARTICIPATION IN 
 ALMA" (R.L.Brown, 12 May 2000), we bring to the enhanced ALMA 
  .additional $30M for site development,
  .additional money for backend subsystem, corresponding to the increased
   number of antennas,
  .increasing contributions for management, system engineering & 
   integration, and science support by Japan by 50%,
  .additional contribution of $10M for computing subsystem by Japan,
 as follows,
                               ALMA                       E-ALMA
　　Management                $24.6M +  12.3            = $ 36.9M
    Site Development           77.9  +  30              =  107.9
    Backend Subsystem(IF,A/D)  32.9  +  32.9*(85-64)/64 =   43.7
    Computing Subsystem        30.7  +  10              =   40.7
    System Engin & Integration 21.3  +  10.7            =   32.0
    Science Support             7.0  +   3.5            =   10.5
       total                                               271.7

○ Total cost (value) of the enhanced ALMA

    Antennas    $ 275 M
    Receivers     161.5
    LO subsystem   68.0
    Correlator      7      (first generation;  NRAO)
                   44      (second generation; Japan & Europe)
    Others        271.7

     Total        827.2M

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