TACTIC%20

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TACTIC MACE gamma-ray telescopes

• Kuldeep Yadav
• ( For HIGRO collaboration)
• Astrophysical Sciences Division
• Bhabha Atomic Research Centre
• Mumbai- 400 085, India

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TACTIC telescope(TeV Atmospheric Cherenkov
Telescope With Imaging Camera)
Control room
TACTIC console
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TACTIC Parameters

• Location Mt. Abu, Rajasthan
  (72.7dE,24.6dN, 1400m asl)
• Light collector 9.5 sq. meter
• Camera FoV 5.9d x 5.9d (349 pixels)
• Trigger FoV 3.4d x 3.4d
• Trigger Criteria 3NCT (Fast RAM based)
• SPE threshold 7pe
• Energy threshold 1 TeV
• Distributed 4-node DAS using RTOS
• Drive Control SM based (120Ncm)
• Observations time 1170 hr/year( Oct-June)
• NIM CAMAC

R.Koul et. al., Nucl. Instrum. and meth. A.,
578(2007) 548
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Multi-node Data Acquisition System
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Mrk 501 observations 1997
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Crab Nebula Observations (2003-04)
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(No Transcript)
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TACTIC observation of MrK 421 (2005-06)
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TACTIC light curve of Mrk 421 (2005-06)
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Crab Mrk 421 concurrent Energy Spectra (2005-06)
K.K.Yadav et. al., Astroparticle Physics,
27(2007) 447
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On-source alpha plot of 1ES2344 514 (60 h
data during 2004-05)
I(1.5 TeV) 3.84 x 10 -12 ph cm-2s-1
S.V.Godambe et. al., J.Phys.GNucl.Part.Phys.
34(2007) 1683
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Mrk 501 observations (2006) 7.5 sigma in 69 h
2005 observation 46h
I(1 TeV) 4.62 x 10 -12 ph cm-2s-1
2006 observation 69h
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Mrk 501 energy spectrum (2006)
f01.660.52 x 10-11cm-2s-1TeV-1 ? 2.8 0.27
S.V.Godambe et. al., J.Phys.GNucl.Part.Phys.
34(2008) 065202
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H1426428 observations (2004,06,07) 150 h
K.K.Yadav et. al., submitted to
J.Phys.GNucl.Part.Phys.
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TACTIC ASM light curves of H1426
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Project HIGRO an introduction A New
Indian initiative in g- ray
astronomy

• Project HIGRO ( Himalayan g- Ray
  Observatory)
• Collaborators --- IIA, TIFR and
  BARC ..
• 7 Element HAGAR wavefront
  sampling telescope
• 21m dia. Stereo MACE ( Major Atmospheric
  Cerenkov
• 
  
  Experiment)
  
• Each telescope element
  will use a cluster of 1408 PMTs
• with a pixel resolution
  of 0.10 FoV 40 x 40.
• Aim Study the sky
  in the unexplored energy
• range E? gt 20
  GeV to bridge the gap between
• the space-based
  and the ground based detectors.

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Hanle, Ladakh (32.7d N, 79d E, 4200m asl)
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Observatory site

Site Characteristics
IIA Campus, HANLE
Location
32.7 0 N, 78.90 E
Lat. And Long
4200 m asl ( 600 g cm -2 )
Altitude
260 Km
Nearest town
8 hrs
Leh- Hanle travel
full year
Accessibility
-20 C (at night)
Med. Temp.
-240 C (at night)
Min. Temp
2m HCT
HAGAR (1/7)
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Med. Rel. Humidity

1. kmph

Med. Wind speed
May - Oct
Time for out door work
High altitude related difficulties
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Advantages of setting up MACE at
HANLE

• Reduction in threshold energy by a
  factor of 2.5-3.5 at
• Hanle ( 4200m asl ) compared
  to lower Altitudes sites like
  Gurushikhar ( 1700m asl).
• Cloud free sky ---
  Spectroscopic Nights 260 nights / yr
  
  
• 
  Photometric Nights 190 night /yr
• Year round sky coverage --
  Quite a few important sources
• cannot be observed at
  Gurushikhar during June-Sept due to
  Monsoon.
• Concurrent observations with
  HAGAR telescope (gt60GeV)
• Coordinated multi-wavelength
  observations with the HCT at Hanle.
  
• Improvement in sensitivity because
  of being closer to shower
• maximum ( images become broader at
  higher altitudes).

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Broad guide lines for designing the MACE
telescope

• Lower the energy threshold to
  20GeV
• (Observation altitude, Large light
  collection area, small coin. gate width,
• appropriate pixel size, CPCs,
  Intelligent trigger generation scheme)
• Employ GHz signal processing using
  Analog Ring Sampler
• Install MACE in the close vicinity
  of the HAGAR array
• Improve detection sensitivity by
  using coincident HAGAR data
• Use central pixel for used for
  optical monitoring of the source ----
• 
  photometric observations
• Fast repositioning of the telescope
  --- high energy tails of GRBs.
• Operate PMTs at a gain of 20,000
  --- ( use partially moon lit nights)
• Improve detection sensitivity
• employ a stereo system in a phased
  manner

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Increase in Cherenkov Photon density with altitude

• .

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Major mechanical sub-systems of the telescope

• Telescope structure material --
• Steel SA-333 Gr 6 (suitable
  for low temp. applications)
• Mirror basket structure
• Aluminum Honey comb panels for
  mounting mirror facets
• Active Miror control (AMC)
  alignment system
• Camera vessel for housing focal
  plane instrumentation Drive
  control system ( DC servo motors with 17 bit
  encoders)
• Track and wheel design concept for
  azimuth motion (27 m dia)
• Camera handling and maintenance
  structure
• Total weight 150 MT
• Overall height of the telescope
  45m
• Operational/ Survival wind speed
  45 km/h // 150 km/h
• Operating temp.
  -300C to 050C ( Winter)
• 
  050C to 300 C (Summer)

Critical design issues Load (Self-weight, 1200 kg camera, Wind load) Deflection, Shadow region, Transportation
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MACE telescope --- Light collector
design

Diameter (area) 2100 cm ( tessellated design 356 panels) 337 m2
Focal distance 2500 ( f/1.2 design)
Individual mirror facets Diamond Milled Al 4 x (050cm X 050cm ) 1 x (100cm X050cm )
Configuration Paraboloid with graded focal length panels
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Expected PSF of the light collector

Plate scale 43.6mm 0.10
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Imaging camera specifications

Requirement of a good camera design --- pixel size and camera FoV
Pixel size depends upon the differences in the characteristic size of gamma-ray and hadron generated Cerenkov images.
Imaging camera
Total pixels 1408
Pixels in trigger region 564
Total FoV 4 0 x 4 0
Trigger FoV 2.4 0 x 2. 4 0
Pixel size (at cpc) 45 mm
photo cathode dia 22/29 mm
Imaging camera Vessel Size 2m x 2m x
2.5m Mass 1200 kg
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Signal Processing Hardware

• 16 channel module
• GHz Sampling
• Integrated Camera
• (all signal processing instrumentation housed
  within the camera structure of
• 2mx2mx1.2m size)
• Temperature control of the Camera during
• operation and standby condition.

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Monte Carlo simulation studies
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Monte Carlo simulation studies Effective
collection area
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Monte Carlo simulation studies Threshold
energy estimates
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Preliminary calculations using Hillas parameters
Standard image
cleaning procedure picture
threshold 4.4pe Boundary threshold
2.2pe. Hillas parameters (
Length, Width, Frac2, Distance, Alpha )
( Dynamic
supercuts with Alphalt80 .)


Detection sensitivity for
Crab
Nebula _at_
5s significance

Tmin 13 mins

( _at_ Sizegt 530pe -- E? gt 200
GeV)

Tmin 43 mins

( _at_ Sizegt50 pe -- E? gt 55 GeV)
MACE sensitivity is still preliminary . We still have a long way to go to improve this figure !!
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Implementation status

• Funding for 1 MACE element already
  approved
• ( 40 crores ) 8 M
• Telescope mechanical design
• ( DDR is completed )
• First Light --- 2010 (Single MACE
  element )
• Agenda for ongoing
  work
• Prototype 256 pixel camera with ARS
  based instrumentation
• being developed at BARC
• Camera design optimization
• ( FOV and Pixel size ---
  arrive at the most optimum configuration)
• Use of WLS dyes for improving
  the QE of PMTs
• Include PMT temporal response in
  MC simulations.
• Use pulse profile information also
  for improving ? /h segregation
• Achieve Tmin lt2 min _at_ E ?gt100 GeV
  using conventional analysis and
• simultaneously use alternative ?
  /h segregation
• methodologies for improving the
  sensitivity _at_ E ? lt 100 GeV

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• THANK YOU