Attendees: Matt Carter (IRAM), Charles Cunningham (NRC), Brian Ellison (RAL), Stephane Guilloteau (ESO), James Lamb (OVRO), Bernard Lazareff (IRAM), John Payne (NRAO), Richard Plambeck (Berkeley), Andreas Stöhr (U. Duisburg), Richard Wade (RAL), and Wolfgang Wild (RUG)
 

The meeting opened with an acknowledgment of the good work done by those responsible for the Project Book. Chapters have been submitted and forwarded.
 

Receiver Production
 

John reported on the 2-day meeting in Garching dealing with receiver integration and production. His observations: 1) that it is very useful to have everyone get together; 2) that there should be three receiver integration centers: U.S., Europe, and Japan; and 3) the emphasis on the receivers being as simple and reliable as possible. Richard questioned how the simplicity requirement can be integrated into the receiver production plan and asked we change what were doing to accomplish that. And what are the cost ramifications? Should this be an action item? What will be the trade-off - simplicity, performance, cost, development - and how do we deal with this? The issue should be raised at the February PDR in Tucson.
 

Wolfgang is in favor of a set of criteria for receiver design and an evaluation of each of the designs using the criteria. The criteria must be realistic with milestones for developing from Phase I into Phase II. A draft of the management plan to be incorporated into the European proposal, to be circulated before Christmas, and to be discussed at next teleconference.
 

James suggested that, besides the three receiver integration centers, there be fabrication centers for sub-units - and that these groups provide cartridges to all integration centers.
 

Marc asked what tasks are capable of being done in Chile - smaller test dewars, clamps, cartridges? John recommended a small test dewar to be built centrally and included in new receiver costing. In testing equipment, each receiver should be evaluated in an identical way. How do you test individual cartridges in the case of Marc's suggestion? Wolfgang agreed that there is a lot more work to be done on this. John suggested that the task be assigned to someone.
 

Wolfgang asked for comments on the Project Book. What is still to be done before the Tucson PDR? Responses included: more detailed design of internal structure radiation shields; finite analysis; cartridges to help with cooling; detailed design of overall thermal loading; IR filter; cryocooler selection. Concern was expressed about acceptable tolerances and the alignment of the dewar.
 

John (to Brian) said his impression is that Anna Orlowska is in favor of the pulse tube concept. Is this correct? John's concern is that it projects out and is difficult to get around. Brian's response: while she is keen on it, she is leaning away from it.
 

There was discussion of the final selection of the cryocooler and the need to revisit this consideration. Should there be two cryocoolers; one on top of the other? Bernard mentioned gravitational factors and improved tolerances.
 

James asked about the possibility of locating the refrigerator somewhere other than the side. He also mentioned that FTS measurements were given in the THz Conference last year - he can distribute them.
 

Dewar and Cryogenic Design
 

Specifications for the 5-day cool-down to include: cool-down will include evacuation; long-term operation on the telescope; and analysis to reduce cool-down time. There are still some refinements to be done with respect to leak rate. The question of additional budget for leakage through window and the consideration that there is the potential for making leak-rate worse than what is stated in document.
 

Status of Optics Design
 

According to James, the 27 November report deadline hadn't been met. There is Bernard's document on tolerance and information has been received on specific details. NRO is responsible for band 8 design and Baryshev for band 9; both layouts are in good shape. Lamb is handling bands 1 and 2; Carter, the other bands. Report should be ready in draft form next week; final version just before/after Christmas.
 

The number of mirrors was questioned; the drawing indicates the space to be tight. Response: the drawing is not quite right. James said this would be less of a problem if positioned closer to feedhorn.
 

Preparation for Receiver PDR

Issues to be included: present optics design and detailed analysis; cryo and dewar design with cartridges; components for individual bands; electronics; production plan; LO parts integrated into frontend; cartridge design for initial bands; outside reviewers (not associated with ALMA) and at least one from industry, suggestions for companies/reps, carbon-fibre specialist, Mitek/Spacetek, Oxford Instruments.
 

John Payne stated concerns about HEMT amplifier. Asked if someone can build a test cartridge. Tucson people are involved with test interferometer.
 

There was a recommendation for a later PDR specific to cartridges; length, positioning, etc. Four initial bands are realizable within the constraints of the cartridges. Won't have sufficiently detailed designs available for the PDR.
 

James voiced his concern about the huge number of wires and needing justification for them. He said there must be reasonable compromises. John Webber added that fewer wires result in simplicity, reliability, performance, cost, and scheduling considerations. John Payne felt this needs to be an assigned task.
 

Wolfgang proposed a list of criteria that can be evaluated for each design solution - reliability, cost, and complexity. And how do we feel about the relative weight of these criteria? James added that we have to have enough information to deal with evaluation; servo drain, biasing the HEMTs, etc. He suggested that a simpler biasing scheme might not be able to measure as well. He also questioned lab results vs. telescope results.
 

John was concerned about conflict in approach: Lamb, simpler; Tony, best receiver that can be built. And his own concerns about the cost, complexity, and reliability factors influencing performance.
 

Next JRDG Teleconference
 

It was decided to reschedule the next meeting to Thursday, 4 January at 16:00 UT. This will be the last teleconference before the PDR, unless another is deemed necessary.
 

Action Items
 

1. Optics Report, James (by Christmas)

2. Mixer/HEMT wiring/diameter of cartridges (Webber/CDL)

3. Preliminary cartridge design (Carter, Harman 20 Dec)

4. Agenda and outline for PDR (John and Wolfgang)