1. Atacama Large Millimeter/submillimeter Array Karl G. Jansky Very Large Array Robert C. Byrd Green Bank Telescope Very Long Baseline Array Band 2 Workshop Introduction Band 2 Design Study Summary E. Bryerton, M. Morgan, M. Pospieszalski, S. Srikanth, K. Saini, D. Vaselaar

2. ALMA Band 2 Workshop Schedule 09:00-09:30 Design Study Overview (Bryerton) 09:30-09:50 GBT 4mm Receiver (Frayer) 09:50-10:10 UAz 4mm Receiver - Part 1 Technical (Lauria) 10:10-10:30 UAz 4mm Receiver - Part 2 Observations (Ziurys) 10:30-10:45 Break [WebEx & audio inactive] 10:45-11:10 Star Formation (Oberg) 11:10-11:35 Deuterium-Bearing Molecules in Dense Cores (Schnee) 11:35-12:00 The Evolution of N2H+ and N2D+ in the Protostellar Phase (Tobin) 12:00-12:30 NH2D and CH2D+ (Wootten) 12:30-13:30 Lunch (supplied by workshop) [WebEx & audio inactive] 13:30-14:00 Studies of Star Formation in the Nearby Universe (Mangum) 14:00-14:20 Redshifted Molecular Gas (Frayer) 14:20-14:45 Discussion of science drivers 14:45-15:15 Panel Discussion 15:15-15:30 Break [WebEx & audio inactive] 15:30- Workshop summary and adjourn Band 2 Workshop Charlottesville, VA 29-May-20132

3. ALMA Band 2 Frequency Range Band 2 Workshop Charlottesville, VA 29-May-20133 Band 3 is 84-116 GHz Current Band 2 Spec is 67-90 GHz

4. ALMA Where Would Band 2 Go? Band 2 Workshop Charlottesville, VA 29-May-20134

5. ALMA Band 2 Workshop Goals Focus on uniqueness of science case Some technical overviews at beginning for context Open discussion encouraged Questions now: – How much overlap with band 3 is desirable? – Is extending band 3 below 84 GHz (to ???) an option? Only if performance in current band 3 range is unaffected? Question to answer in ~2 years time – Is full installation of band 2 receivers on ALMA worth the approximate $12M price tag? Band 2 Workshop Charlottesville, VA 29-May-20135

6. ALMA ALMA Development Program Funding lines in NA, EU, and EA Two types: Design Studies & Development Projects Development Projects – Funding ramps up to $13.6M per year total from all partners in 2015 – ~$5M per year from NA – Required ASAC approval and JAO coordination $500K per year per partner in design studies (strictly regional) – One-year, <$200K – Current NA and EU band 2 efforts are design studies Band 2 Workshop Charlottesville, VA 29-May-20136

7. ALMA Current Development Projects Band 5 Construction – European led effort for full installation of band 5 on all antennas – ESO spending ~$16M from 2013-2017 (all their project funding) – NA-NRAO supplying LO (~$3M) Fiber Connection OSF-Santiago – 25x increase in data rate ALMA Phasing Project (VLBI) – $0.52M from ALMA-NA, remaining funds from NSF MRI Band 1 (EA) – Nov. 2012: ALMA Board approved development of prototype band 1 receiver Band 2 Workshop Charlottesville, VA 29-May-20137

8. ALMA NA FY14 ALMA Development Call for Proposals Development Projects – $4.3M total available in FY14 and FY15 – $1.5M maximum award (over two-year period) Design Studies – $1M available in FY14 – Will be another call for FY15 ($500K available) Band 2 Workshop Charlottesville, VA 29-May-20138

9. ALMA European Band 2 (+3) Design Study 18-month study begun in June 2012 (STFC / IRAM / INAF) Deliverables: Science case, study of key technologies to develop a band 2 or a band 2+3 cartridge design Science Workshop held earlier this week Band 2 Workshop Charlottesville, VA 29-May-20139

10. ALMA NA Band 2 Design Study Overview Joint NRAO-ARO Study Oct. 2012 – Sep. 2013, $100K Concentrate on demonstrating technology readiness of key components – Low-noise amplifiers – OMT – Optics – Downconverter Science Motivation – Unexplored bandwidth, especially with interferometry – Deuterated species in cold cores – Galaxies at intermediate redshift – Complex organics Band 2 Workshop Charlottesville, VA 29-May-201310

11. ALMA Band 2 Gain/Noise Budget Band 2 Workshop Charlottesville, VA 29-May-201311 Component/StageGain (dB)Noise Temperature (K)T EQ (K) referenced to the input Lens/Window (297K)-0.1611.1 IR Filters (15K, 110K)-0.12.52.6 Feedhorn (15K)-0.10.350.4 OMT (15K)-0.10.350.4 Cryogenic LNA (15K)30 33.4 Cryogenic Isolator (15K)3.9insignificant Cryogenic Postamp (15K)25800.1 Waveguide Feedthru (297K)77insignificant Donwnconverter (297K)-155000insignificant Warm IF Amplifier (297K)20175insignificant Total57.548.0 Table 2: Preliminary gain and noise budget for the ALMA band 2 receiver. Current ALMA Band 2 Noise Specification: 30 K SSB over 80% of the RF band and 47 K SSB at any RF frequency in the band, where the RF band is defined as 67-90 GHz. Given baseline optics design (warm refractive optics), this is extremely difficult and perhaps impossible (requires LNA with <15K noise temperature) Slightly more realistic would be cold lens and a LNA with 20K noise temperature Really need reflective optics, but may not fit (currently under study)

12. ALMA Band 2 Turnstile-Junction OMT Band 2 Workshop Charlottesville, VA 29-May-201312 X-band (8-12 GHz), Ku-band (11-18 GHz), and Q-band (35-52 GHz) versions already demonstrated Band 2 version (currently in fabrication) will be ~32 grams (not including #0-80 screws)

13. ALMA Band 1 OMT Measurements 13Band 2 Workshop Charlottesville, VA 29-May-2013 Three Band 1 OMTs fabricated and measured

14. ALMA Insertion Loss In Al, Au Band 1OMTs 14Band 2 Workshop Charlottesville, VA 29-May-2013 Gold Plating Nominal zincate Alkali copper : 25 μ Pur-a-gold 125: 50μ S 21 0.3 to 0.35 dB Theory 0.34 dB at 40 GHz for Au Predicted S 21 of 0.12 dB at 15K

15. ALMA Proposed Band 1 OMT and Amplifier Layout 15Band 2 Workshop Charlottesville, VA 29-May-2013 Band 2 Cartridge layout will be similar

16. ALMA Low Noise Amplifiers for Band 2 16 Band 2 Workshop Charlottesville, VA 29-May-2013 3-stage MMIC LNA (MMIC-A and MMIC-B two different designs) 6-stage hybrid LNA (WM###)

17. ALMA Low Noise Amplifiers for Band 2 Band 2 Workshop Charlottesville, VA 29-May-201317 Two 35nm MMIC designs have been tested, both 3-stage with ~30dB gain 2 of 3 35nm wafer runs so far have given good cold results (4 th run preliminary results encouraging) Samples from APRA3 35nm wafer recently delivered, will be tested this summer Broadband Cryo3 MIC LNA to be tested this summer Current generation of 35nm MMIC design are 3-stage, 30 dB gain. Would really like 4-stage, 40 dB gain (eliminates need for 2 nd cold LNA)

18. ALMA Proposed Band 2 Block Diagram Band 2 Workshop Charlottesville, VA 29-May-201318

19. ALMA Band 2 Multi-Chip I/Q-Mixer LO=75 GHz LO=80 GHz Commercial MMIC mixers Machined RF quadrature hybrid and LO splitter Tested with external Band 6 IF hybrid (coaxial, not shown) Band 2 Workshop Charlottesville, VA 29-May-2013 19

20. ALMA Band 2 MMIC I/Q-Mixer Chip PhotoSimulated Performance Band 2 Workshop Charlottesville, VA 29-May-2013 20 (fixed IF)

21. 21Band 2 Workshop Charlottesville, VA 29-May-2013 The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. www.nrao.edu science.nrao.edu