• Proposal 553 LAMAS (Large-Area Mapper for ALMA Study): Multi-beam Receivers for the ALMA Total Power Array

  • Referee 3
Grade: 8

LAMAS (Large Area Mapper for ALMA Study): Multi-Beam Receivers for the ALMA Total Power Array

1. Alignment with NA ALMA Partnership strategic goals; -- OK, in that mapping wide fields is a goal.

2. Strength of the scientific case for the proposed ALMA upgrade concept; Comment on the relevance to the ‘ALMA 2030’ development documents. -- Increasing the mapping speed of the 4 total power antennas could benefit many observations of molecular clouds and nearby galaxies. However, previous studies (e.g., Henke et al.) suggest that cramming a PAF or FPA into the footprint of the existing ALMA dewar would boost the mapping speed by only a factor if a few, which is not worth the huge cost in development and construction.

3. Quality of the upgrade conceptual design; -- The parameter space to be investigated in this study is too large. One wonders whether the outcome of this open-ended exercise will be a concrete plan, or just a table listing all the tradeoffs that will leave the whole issue unsettled. To its credit, this proposal does consider the possibility of constructing new dewars for the 4 total power antennas, which is likely to be necessary in order to achieve meaningful improvements in mapping speed.

4. Readiness for production in the context of the ALMA Development Plan (the aim is to support a range of upgrades including both those which can be implemented rapidly and those requiring longer-term research and development); -- This is a very long term project.

5. Strength of the consortium organization (if applicable); -- Excellent. The University of Arizona team has built some of world's largest array receivers.

6. Qualifications of the key personnel of the Study; -- Excellent.

7. Technical expertise, past experience (also in series production, if relevant) and technical facilities in the Institutes taking part in the Study; -- Good.

8. Assessment of the level of risk inherent in the design; -- High risk.

9. Strength of the Scientific Team supporting the Study; -- Good.

10. Level of support guaranteed by the Institutes; -- OK.

11. Budgeted cost of the Study; -- OK.
  • Referee 4
========================================================

Grade: 6

Title: LAMAS: Multi-beam Receivers for the ALMA Total Power Array (PI: Groppi)

1. Alignment with NA ALMA Partnership strategic goals;

Comment: This proposal aims to extend the technical capability and increase the operating efficiency of ALMA by addressing the development of multi-beam receiver systems for ALMA. The involvement of the University instrumentation groups is also a major step for strengthening the NA radio astronomy community.

2. Strength of the scientific case for the proposed ALMA upgrade concept; Comment on the relevance to the ‘ALMA 2030’ development documents.

Comment: This study aims to address one of the key recommended development paths of increasing the wide field mapping speed. The scope of the study is limited to the four 12m total power array antennas, but the topics proposed include a wide range, including feed design, different freq. bands, FP architecture, mechanical and cryo systems, and backend.

The scope of work seems a bit too ambitious, considering the majority of the stated work and budget rely largely on a single graduate student. The overall upgrade to a multi-beam receiver system for the entire ALMA array would require a major campaign of feasibility studies and technical design work by a larger group of the entire ALMA consortium. The overall impact of this proposed study may not be substantial, in the absence of the larger framework.

3. Quality of the upgrade conceptual design;

Comment: One study of the previous feed design by Henke et al. (2016) is mentioned with very little specifics. Current progress in other areas also lack some specifics and context.

4. Readiness for production in the context of the ALMA Development Plan (the aim is to support a range of upgrades including both those which can be implemented rapidly and those requiring longer-term research and development);

Comment: Stated goals are numerous, yet lack sufficient details to offer a good sense for readiness.

5. Strength of the consortium organization (if applicable);

Comment: This collaboration involving two university groups and integration of student training is a real positive for this proposal. The scope of work proposed seems excessive, however, considering the man power allocated.

6. Qualifications of the key personnel of the Study;

Comment: The PI and the co-I have a proven track record on building multi-beam receiver systems.

7. Technical expertise, past experience (also in series production, if relevant) and technical facilities in the Institutes taking part in the Study;

Comment: See above. It is not clear from the proposal whether the participating institutions have sufficient technical facilities to carry out the proposed studies.

8. Assessment of the level of risk inherent in the design;

Comment: The schedule risk, as identified in the proposal, maybe more substantial than estimated, given the extensive set of goals stated.

9. Strength of the Scientific Team supporting the Study;

Comment: Both the PI and the co-I have extensive experience as members of the teams that produced several multi-beam receivers.

10. Level of support guaranteed by the Institutes;

Comment: not clear

11. Budgeted cost of the Study;

Comment: seems reasonable for the personnel identified, but the amount of work might have been under-estimated. Is the institutional overhead included in the budget?

  • Referee 12
Grade: 3.0

Title: 553 LAMAS (Large-Area Mapper for ALMA Study): Multi-beam Receivers for the ALMA Total Power Array

1. Alignment with NA ALMA Partnership strategic goals

No stated collaboration with Partners (ESO, NAOJ, or JAO). Strategic goals are aligned.

2. Strength of the scientific case for the proposed ALMA upgrade concept Comment on the relevance to the ‘ALMA 2030’ development documents.

The study is directly relevant to the ALMA 2030 (#4) document.

3. Quality of the upgrade conceptual design

The study is proposed as very comprehensive, addressing feed design, architecture, backend, mechanical, cryostat modifications, frequency band priority assessment, mapping speed assessments, strawman designs for each band, and even PAF consideration. Each of these topics will be important for future implementation of multi-beam receivers for ALMA.

Each topic is given a high-level description and the goals for some sections appear a bit optimistically broad (e.g., section 4.3 “For each band we will develop and analyze strawman multi-beam designs that retain all RF capabilities and expected performance of existing ALMA bands, and analyze the impacts of technical descopes that could offer much greater implementation feasibility with acceptable performance penalties while offering the number of pixels determined from the previous trades.”). I believe a drawback of the study is that the comprehensive nature does not match the timeline or labor estimate of a 1-year study. However, the investigators are highly experienced and this will help to compress the timeline.

De-scoping the study would likely improve the outcome and strength of the proposal, e.g.: limit designs to one frequency band, perhaps don’t include PAFs, concentrate on a few key issues for mechanical integration, etc.

4. Readiness for production in the context of the ALMA Development Plan (the aim is to support a range of upgrades including both those which can be implemented rapidly and those requiring longer-term research and development)

This study is aimed towards longer-term research and states that follow-on studies/projects could be applicable. 5. Strength of the consortium organization (if applicable)

6. Qualifications of the key personnel of the Study

Highly qualified.

7. Technical expertise, past experience (also in series production, if relevant) and technical facilities in the Institutes taking part in the Study

Very relevant past experience in multi-beam receivers, both in written work and implementation (Supercam, KAPPa, etc).

8. Assessment of the level of risk inherent in the design

The study does not pose significant risk (except timeline).

9. Strength of the Scientific Team supporting the Study

Strong supporting team.

10. Level of support guaranteed by the Institutes

Not explicitly stated.

11. Budgeted cost of the Study

-- AlWootten - 2017-08-03
Topic revision: r1 - 2017-08-03, AlWootten
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