07 Feb, 2009Rencontres de Moriond 20091 TACTIC & MACE gamma-ray telescopes Kuldeep Yadav ( For HIGRO collaboration) Astrophysical Sciences Division Bhabha

07 Feb, 2009 Rencontres de Moriond 2009 1

TACTIC & MACE gamma-ray telescopes

Kuldeep Yadav( For HIGRO collaboration)

Astrophysical Sciences DivisionBhabha Atomic Research Centre

Mumbai- 400 085, India


TACTIC telescope(TeV Atmospheric Cherenkov Telescope With Imaging

Camera)

Controlroom

TACTICconsole


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


Multi-node Data Acquisition System

Semaphore Manager

CAMAC Driver

LEDDriver

GAINCONTROL

HVDRIVER

LEDCAMACSCALER

G A I N C O N T R O L N O D E

SCALER Test HV Test

PCRCCR

QN X NODE #3

HV

QNX NODE # 1

C D C D A T A N O D E

SHAREDMEMORY

CAMAC Driver

Linux NODE # 4

--- Data Processing--- Display--- Data quality check--- Archiving

QNX NODE # 2

CDC DATA - EVENT - CALIBRATION - SKY-NOISE

CAMAC CDC CAMAC TTG`

INTERRUPT HANDLER

- Master Process- Display Manager- Data Storage

TCP - IP

ACE Event

Calibration Event

( From TTG )

LED Driver

Chance Event

Linux NODE # 4Linux NODE #5

--- Data Processing--- Display--- Data quality check--- Archiving

Multi-node DA & CS of TACTIC


Mrk 501 observations 1997

0

2

4

6

0

2

4

6

Modified Julian Date

50520 50550 505800

2

4

6 -

Ray

Sig

nal

( cr

ab u

nits

)

CAT

WHIPPLE

TACTIC

HEGRA

Mkn - 501 ( April - May , 1997 )

0

2


Crab Nebula Observations (2003-04)

Alpha (deg)

0 9 18 27 36 45 54 63 72 81 90

Nu

mb

er o

f e

ven

ts p

er 9

0

bin

2400

2600

2800

3000

3200

3400

NO OF IMAGES (TOTAL)= 680518 NO OF IMAGES (FILT.) = 26615 % IMAGES SELECTED = 3.91 GAM DOM. EVTS (0-15) = 6081 + 78 COS.BG. EVTS (0-15) = 5121 + 38 EXCESS EVTS (0-15) = 960 + 87 SIGNIFICANCE = 11.05 AVG.BG EVTS./ BIN = 2561 + 19

OBS TIME ( h) = 103.6081 RBL RATE (/h) = 24.71 0.18 GAMMA-RAY RATE (/h) = 9.26 0.84

Gamma-rays :( 960 + 87) Significance : 11.05

Recent observation on Crab Nebula with TACTIC ( Nov.2003 -Feb.2004)


Crab Nebula - Differential energy spectrum ( Comparison with other systems )

Energy (TeV)

1 10

Dif

ere

nti

al f

lux

(p

ho

ton

s cm

-2 s

-1 T

eV-1

)

10-16

10-15

10-14

10-13

10-12

10-11

10-10TACTIC FLUX POINTSHEGRA SPECT RUMWHIPPLE SPECTRUMTACTIC BEST FIT SPECTRUM

(3.18 + 0.41) x 10 -11 ( E / 1TEV )-2.65 + 0.11 cm-2 s-1 TeV -1

HEGRA SPECTRUM

TACTIC SPECTRUM

WHIPPLE SPECTRUM

(2.79 + 0.02) x 10 -11 ( E / 1TEV )-2.59 + 0.03 cm-2 s-1 TeV -1

(3.20 + 0.17) x 10 -11 ( E / 1TEV )-2.49 + 0.06 cm-2 s-1 TeV -1


TACTIC observation of MrK 421 (2005-06)


TACTIC light curve of Mrk 421 (2005-06)


Crab & Mrk 421 concurrent Energy Spectra (2005-06)

K.K.Yadav et. al., Astroparticle Physics, 27(2007) 447


On-source alpha plot of 1ES2344 + 514 (60 h data during 2004-05)

S.V.Godambe et. al., J.Phys.G:Nucl.Part.Phys. 34(2007) 1683

I(≥1.5 TeV) ≤ 3.84 x 10 -12 ph cm-2s-1


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


Mrk 501 energy spectrum (2006)

S.V.Godambe et. al., J.Phys.G:Nucl.Part.Phys. 34(2008) 065202

f0=1.66±0.52 x 10-11cm-2s-1TeV-1

ſ = 2.8 ± 0.27


H1426+428 observations (2004,06,07) ~150 h

K.K.Yadav et. al., submitted to J.Phys.G:Nucl.Part.Phys.


TACTIC & ASM light curves of H1426


Project HIGRO an introduction A New Indian initiative in - ray astronomy

Project HIGRO ( Himalayan - 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 Eγ > 20 GeV to bridge the gap between the space-based and the ground based detectors.


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


Observatory site

10 kmphMed. Wind speed

IIA Campus, HANLE

Location

4200 m asl (~ 600 g cm -2 )

Altitude

32.7 0 N, 78.90 ELat. And Long

8 hrsLeh- Hanle travel

260 KmNearest town

-240 C (at night)

Min. Temp

May - Oct Time for out door work

-20 C (at night)

Med. Temp.

30% Med. Rel. Humidity

full yearAccessibility

Site Characteristics

2m HCT

Telescope site IIA Campus , Hanle 4200 m asl (~ 600 g cm -2 )

HAGAR (1/7)

High altitude related difficulties


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 (>60GeV) &

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).


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


.

Increase in Cherenkov Photon density with altitude


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


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

X (cm)

-1200 -1000 -800 -600 -400 -200 0 200 400 600 800 1000 1200

Y (

cm)

-1200

-1000

-800

-600

-400

-200

0

200

400

600

800

1000

1200

Zone # 01

Zone # 02

Zone # 03

Zone # 04

Zone # 05

Zone # 06

Zone # 07

Zone # 08

Zone # 09

Zone # 10

Zone # 11

B L A N K


Expected PSF of the light collector

Angle of incidence ( deg)

0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75

D 8

0 (

mm

)

0

5

10

15

20

25

30

35

40

45

50

55

60

65

70

Graded fConstant fDavies-CottonSingle Paraboloid

Pixel Diameter

=0.00 =0.50

=1.00 =1.50 Plate scale :

43.6mm ~ 0.100

Plate scale : 43.6mm =0.10


Imaging camera specifications:

X (deg)

-2 -1 0 1 2

Y (

deg

)

-2

-1

0

1

2

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

Imaging camera Vessel

Size : 2m x 2m x 2.5m

Mass : 1200 kg

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.


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.


Monte Carlo simulation studies

CORSIKA air shower simulation code Energy range -- 1 - 1000 GeV for gamma-rays & e; 10 - 10000 GeV for p & alpha

Observatory altitude : 4200 m asl ( Hanle) LONS background : 3.0 x 10 12 photons m-2 s-1 sr-1

No. of showers generated : 8 x 106 each for γ, p , α & e

Zenith angle : Vertical incidence Impact parameter : 0-400 m for gamma -rays, e & p ; 0-500 m for alpha

Mirror reflectivity, CPC collection efficiency, : Taken into account Atmospheric extinction Trigger FoV : 2.40 x 2.40

Single pixel threshold ~ 4 pe Trigger generation logic : NNQ


Monte Carlo simulation studies– Effective collection area

Energy ( GeV)10 100 1000

Eff

ec

tiv

e c

olle

cti

on

are

a (

m

2 )

101

102

103

104

105

106

Gamma Electron

Proton Alpha


Monte Carlo simulation studies – Threshold energy estimates

Energy ( GeV)10 100 1000

Dif

fere

nti

al ra

te (

s

-1 G

eV

-1)

10-2

10-1

100

101

102

Gamma

Electron

Proton

Alpha

E(trig) ~ 20 GeV

Ep(trig) ~ 150 GeV

Ee(trig) ~ 20 GeV

E(trig) ~ 500 GeV


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 Alpha<80 .)

Detection sensitivity for Crab

Nebula @ 5σ significance

Tmin ~ 13 mins ( @ Size> 530pe -- Eγ > 200

GeV)

Tmin ~ 43 mins ( @ Size>50 pe -- Eγ > 55

GeV)Energy ( GeV)

10 100 1000

Dif

fere

nti

al r

ate

( s

-1 G

eV -1

)

10-6

10-5

10-4

10-3

10-2

10-1

100

101

Trigger threshold ~ 35 GeV

Analysis threshold

@ >50pe ~ 55 GeV

@ >530pe ~ 200 GeV

Size > 50 pe

Size > 530 pe

Trigger

• MACE sensitivity is still preliminary .

• We still have a long way to go to improve this figure !!


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 γ /h segregation

Achieve Tmin ~ <2 min @ E γ>100 GeV using conventional analysis and

simultaneously use alternative γ /h segregation

methodologies for improving the sensitivity @ E γ < 100 GeV

Simulation for stereo MACE Repeat simulations at different zenith angles & also at lower altitude

(~1600 m) for quantifying the quantum of sensitivity improvement at

higher altitude.


.

THANK YOU

Documents

07 Feb, 2009Rencontres de Moriond 20091 TACTIC & MACE gamma-ray telescopes Kuldeep Yadav ( For HIGRO collaboration) Astrophysical Sciences Division Bhabha