alma science workshop may 14-15, 2004 ca. mar 2, 2004 the large millimeter telescope

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


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


LMT Specifications


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


LMTDesign

SurfaceSegments

ElevationWheels

Alidade

Foundation

Backstructure

ReceiverCabin


Construction at Site

January 2001 January 2002 February 2002

May 2002 July 2002 April 2003


Present Status at Site

April 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


● 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)


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


● Dual polarization – two beams

● Backend spectrometer is analog autocorrelator with 6.5 GHz bandwidth per section. 30 MHz resolution.


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.


1mm SIS Commissioning Receiver for LMT (testbed for future focal-plane array)


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


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


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


Protogalaxy Interrogation with SPEED

SED of CFRS14A

SPEED

SPEED 5σ sensitivities after 4 minutes of integration at LMT.


Comparison of LMT to Other Telescopes


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 --


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.


LMT Sensitivity to Distant Dusty Starburst

Galaxies


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.


LMTO: A Scientific CollaborationLMTO: A Scientific Collaborationbetween the US and Mexicobetween the US and Mexico


LMT Site MM-wave Transmission

8mmppt-H2O

2mmppt-H2O

8mmH2O

2mmH2O

Site Opacity Quartilesbased on RadiometricMeasurements

Predicted Transmission for2mm and 8mm ppt water vapor


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.


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.


LMT Surface Segment

Surface Panel

Subframe

Actuatorfor ComputerControl


Composite Optics Inc.Composite Optics Inc.San Diego CASan Diego CA

Critical Design Review for First Critical Design Review for First PanelPanel

alma science workshop may 14-15, 2004 ca. mar 2, 2004 the large millimeter telescope

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