[asac] Receiver Issues

[Al Wootten]

Hi Al,

please find a short note of John Payne and myself about some receiver
issues for the next ASAC meeting.

Wolfgang
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ALMA Receiver Issues
=================

For the attention of the ASAC

5 September 2000, W. Wild and J. Payne

We would like to ask the ASAC to comment on the following issues which are of great importance for the 
further progress of the receiver design.

Receiver calibration
------------------------
There seem to be different opinions regarding the inclusion of a cold load or not in the receiver optics design. 
The design has reached a point where a clear decision cannot be further delayed without delaying the receiver 
program. At the receiver groups request, two ALMA memos have been written concerning the receiver 
calibration system (memo # 321 by R. Plambeck, and memo # 318 by J. Mangum). R. Plambeck concludes that 
cold loads are not worth the complexity. We would like to have the ASAC's opinion whether a cold load is 
required to meet the scientific goals of the array.

Receiver specifications
----------------------------
A new draft version of the receiver specifications (draft 1.4) has been released, taking into account many 
comments of the ASAC and other groups. We would like to know if the ASAC considers these specification 
adequate. In particular, we would like some reassurance that the specifications on polarization (3.2) are 
adequate.

It is planned that J. Payne and W. Wild phone in to the ASAC meeting.