alma science workshop may 14-15, 2004 ca. mar 2, 2004 the large millimeter telescope
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ALMA Science Workshop May 14-15, 2004ca. Mar 2, 2004
TheTheLargeLargeMillimeterMillimeterTelescopeTelescope
ALMA Science Workshop May 14-15, 2004
Gopal Narayanan, Min Yun, F. Peter SchloerbUniversity of Massachusetts
Luis Carrasco Instituto Nacional de Astrofisica, Optica, y Electronica
presented on behalf of the INAOE-UMass LMT Collaboration
ALMA Science Workshop May 14-15, 2004
Sierra NegraThe LMT Site
● state of Puebla, MX● excellent mm-wave
transmission● 4600m elevation● 19 degrees Latitude● Benign conditions● Development nearly
complete
Sierra NegraPico deOrizaba
ALMA Science Workshop May 14-15, 2004
LMT Time Line● 1997: Site Selection
● 1997-2000: Antenna Design
● 1999-2002: Site Preparation and installation of Foundation
● 2001: Factory Steel Fabrication and Trial Assembly
● 2002-2004: Installation of Steel at Site
● 2004-2006: Fabrication of Surface Panels
● 2005-2006: Installation of Surface Panels
● 2005: Commissioning Begins
ALMA Science Workshop May 14-15, 2004
LMTDesign
SurfaceSegments
ElevationWheels
Alidade
Foundation
Backstructure
ReceiverCabin
ALMA Science Workshop May 14-15, 2004
Construction at Site
January 2001 January 2002 February 2002
May 2002 July 2002 April 2003
ALMA Science Workshop May 14-15, 2004
Initial LMT Instruments● Spectral Line
– SEQUOIA – 32 element array for 3mm band– Array Autocorrelation Spectrometers– Redshift Receiver – 3mm ultrawide band
receiver– 1mm SIS Receiver
● Continuum
– BOLOCAM II – 144 element focal plane array– SPEED – special array for spectral energy
distribution measurements
ALMA Science Workshop May 14-15, 2004
● 85 – 115 GHz dual-polarized 16 pixel receiver
● 5 – 20 GHz IF allows 2 lines to be observed simultaneously
● FCRAO/LMT On-the-Fly Mapping Technique with Focal Plane Arrays powerful for large scale-mapping
SEQUOIA
Goldsmith, Narayanan, Heyer, Snell & Brunt (2004)
ALMA Science Workshop May 14-15, 2004
Redshift Search Receiver
● Ultra-wideband receiver for astronomical search for the highly redshifted spectral lines from distant galaxies.
● 75-111 GHz gives high probability of detecting one line from galaxies with redshift greater than 1.1 and 2 lines for Z > 3
2mm, 5mm PWV, TRCR = 60K
ALMA Science Workshop May 14-15, 2004
● Dual polarization – two beams
● Backend spectrometer is analog autocorrelator with 6.5 GHz bandwidth per section. 30 MHz resolution.
ALMA Science Workshop May 14-15, 2004
LMT Redshift Measurements
Simulations based on dusty QSO BR 1335-0417. ULIRG Line Ratios
LMT has sensitivity to conduct follow-up studies on objects discovered in continuum surveys.
ALMA Science Workshop May 14-15, 2004
1mm SIS Commissioning Receiver for LMT (testbed for future focal-plane array)
ALMA Science Workshop May 14-15, 2004
First Generation Continuum Receivers for LMT
BOLOCAM II
• Imaging continuum receiver
• copy of the BOLOCAM instrument(Caltech, JPL, Cardiff, Colorado)
• 144 element focal plane array
-key technology forHerschel/SPIREBLAST
BOLOCAM detector array
ALMA Science Workshop May 14-15, 2004
LMT Continuum Studies of Distant Objects
LMT will discover many 1000's of protogalaxies with continuum maps.
Simulation by Chapin, Hughes and Gaztenaga - INAOE
Simulation of ~1 hour LMTobservation with Bolocam II at 1.1 mm
9.5x9.5 arcmin (0.02 sq. deg.)
0.5 mJy rms
ALMA Science Workshop May 14-15, 2004
SPEED
• designed to measure mm-wave SED of previously detected objects
• simultaneous multi-frequency measurements• matched beams in all bands• high per-pixel sensitivity
• takes advantage of new bolometer technologies
• TES detectors• Frequency Selective Bolometers
First Generation Continuum Receivers for LMT
Ch.4
Ch.3Ch.2
Ch.1
FSBDetector
FSBBackshort
ALMA Science Workshop May 14-15, 2004
Protogalaxy Interrogation with SPEED
SED of CFRS14A
SPEED
SPEED 5σ sensitivities after 4 minutes of integration at LMT.
ALMA Science Workshop May 14-15, 2004
Performance Comparison With Respect to the LMT
ALMA CARMA GBTCollecting Area 3.7 0.4 4
Flux Sensitivity Line (3mm) 0.38 3.6 0.58 Continuum (1mm) 0.48 9 --
Brightness Sensitivity Line (3mm) 3.5 4.7 2.3 Continuum (1mm) 4.4 12 --
Mapping Speed Line (3mm) 0.17 0.13 0.003 Continuum (1mm) 0.025 0.005 --
ALMA Science Workshop May 14-15, 2004
Analog Autocorrelator
●Like digital autocorrelator but delays and multiplies done with analog circuitry. No input digitizer, so no loss of S/N. Much wider bandwidth practical.
●Analog delay lines Nyquist sampled for 8 GHz bandwidth. Only 1.5-8 GHz used.
●64 lags on each tapped line, 4 lines per board. 256 lags total giving 31 MHz resolution, all on a single circuit board.
●Taps are summed and multiplied with silicon diodes.
●Circuit board includes A/D converters and digital signal processing.
●24 boards cover full receiver bandwidth of 144 GHz.
●Total materials cost about $10/resolution element.
ALMA Science Workshop May 14-15, 2004
OperationsThe Large Millimeter Telescope
Observatory● LMTO Role
– Telescope maintenance and operation– Development of plans for upgrades– Telescope user support– Outreach
● LMTO Organization– Governing Board composed of INAOE and
UMass personnel oversees LMTO.– LMTO is separate entity with an
indepentent Director and Staff.
ALMA Science Workshop May 14-15, 2004
LMTO: A Scientific CollaborationLMTO: A Scientific Collaborationbetween the US and Mexicobetween the US and Mexico
ALMA Science Workshop May 14-15, 2004
LMT Site MM-wave Transmission
8mmppt-H2O
2mmppt-H2O
8mmH2O
2mmH2O
Site Opacity Quartilesbased on RadiometricMeasurements
Predicted Transmission for2mm and 8mm ppt water vapor
ALMA Science Workshop May 14-15, 2004
Antenna Design ● Antenna Designer: MAN Technologie● "Open Air" Design (no enclosure).● Active Surface
– 180 trapezoidal surface segments.– Actuators at four corners of segments.– open-loop lookup table for positioning.
● Use of Active Surface eliminates gravitational distortion as major error source.
ALMA Science Workshop May 14-15, 2004
Antenna Fabrication
● Steel Fabrication– Adriann's de Mexico, Tlanepantla, Mexico– Supervision by Antedo, Inc., Cupertino CA.– Steel Fabrication is complete; antenna
being assembled at site● Surface Panels
– Design and Development by Composite Optics Inc. (COI), San Diego, CA
– Fabrication at Adriann's de Mexico– Panel fabrication to begin this year.
ALMA Science Workshop May 14-15, 2004
LMT Surface Segment
Surface Panel
Subframe
Actuatorfor ComputerControl
ALMA Science Workshop May 14-15, 2004
Composite Optics Inc.Composite Optics Inc.San Diego CASan Diego CA
Critical Design Review for First Critical Design Review for First PanelPanel