[mmaimcal] ASAC Draft Minutes

[Al Wootten]

ALMA Science Advisory Committee

Teleconference

9 October 2000

Draft Minutes

Participants: R. Bachiller, A. Benz, R. Booth, P. Cox, R. Crutcher, N.
Evans, S. Guilloteau, M. Ishiguru, K. Menten, J. Payne, P. Shaver, E.
van Dishoeck, M. Walmsley, W. Wild, C. Wilson, A. Wootten, M. Yun


1. Report from Berkeley Face-to-Face Meeting

The draft version was briefly discussed, in particular the sections
concerning polarization, site and receivers bands. The possible
extension of band 1 to somewhat lower frequencies was discussed, to
improve overlap with the ELVA and further enhance science capabilities
(particularly Zeeman splitting observations of the 30 GHz transition of
SO) – this will be mentioned in the report. The final version of the
report will be completed on 10th October and submitted in time for the
ACC meeting.


2. Receiver Group Reports

W. Wild and J. Payne reported on two recent meetings of the Receiver
Group. At the Cambridge meeting there were three main points: receiver
specs, calibration, and optics. The specs had been revised; the ASAC
felt that these should not be determined by technology. Concerning
calibration, the receiver group agreed with the ASAC that it was not
worthwhile to include cold loads. The new optics design is underway. The
HFET vs SIS decision for band 3 is under study – stability and
saturation are important issues. E. van Dishoeck raised the issues of
tuning range and switching between sub-bands. W. Wild replied that this
is also under study, and decisions should be made shortly. From the
optics meeting, J. Payne said that there has been good progress, and a
report will be issued shortly. R. Crutcher asked about off-axis beams
and expressed concern for polarization. W. Wild said that if one
receiver is to be on-axis (as suggested in the Leiden report), it will
add complication and require a re-design. S. Guilloteau commented that
calibration may actually be easier with the mirrors of an off-axis
system. Finally, it was reiterated that the WVR would be uncooled (or
have its own cooling).


3. ALG Issues

N. Evans and P. Cox reported on the ALG meeting of 11 September. N.
Evans expressed concern about the ALG’s interpretation of ASAC
recommendations on the number of 12m antennas and receiver priorities,
but any misunderstandings should have been clarified by the Berkeley
ASAC report. Brief summaries were given of the ALG discussions on
correlators, the ACA, Japanese news on LMSA, ASTE, receiver and photonic
developments, and steps towards a three-way agreement. M. Ishiguru
mentioned unresolved issues, including the number of 12m antennas and
the capability of the enhanced correlator.


4. Site Issues

A. Wootten mentioned some studies currently in progress on site issues.
B. Butler and S. Radford are completing comparative studies of the
Chajnantor and Pampa La Bola sites, and G. Delgado has presented a
report on a 52-year climatological study for the Chajnantor area done by
a consultant. A meeting will take place next month in Charlottesville to
review the CBI experience. Reports from all these activities will be
prepared in time for the Morroco meeting on site testing in November.


5. Next Meeting

The next ASAC teleconference is scheduled for Monday 13th November.