Transcript CANGAROO - Institute for Cosmic Ray Research

CANGAROO-III and beyond
Masaki Mori*
for the CANGAROO team
*ICRR, The University of Tokyo
Pre-ICRC workshop: New Generation Cherenkov Imaging Telescopes
Aug 1-2, 2005, Mumbai, India
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“CANGAROO”
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Collaboration of Australia and Nippon for a
GAmma Ray Observatory in the Outback
Woomera, South Australia
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CANGAROO team
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University of Adelaide
Australian National
University
Ibaraki University
Ibaraki Prefectural
University
Konan University
Kyoto University
STE Lab, Nagoya
University
National Astronomical
Observatory of Japan
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Kitasato University
Shinshu University
Institute of Space and
Astronautical Science
Tokai University
ICRR, University of
Tokyo
Yamagata University
Yamanashi Gakuin
University
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Brief history of CANGAROO
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1987:
1990:
1990:
1992:
1994:
1998:
1999:
2000:
2001:
2002:
2004:
SN1987A
3.8m telescope
ICRR-Adelaide Physics agreement
Start obs. of 3.8m tel.
PSR 1706-44
SNR1006
7m telescope
Upgrade to 10m
U.Tokyo-U.Adelaide agreement
Second and third 10m tel.
Four telescope system
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Why Woomera?
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NZ: too wet, not
many clear nights
Woomera:
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Former rocket range
and prohibited
area…infra-structure
and support
Adelaide group was
operating BIGRAT
ELDO rocket Launch site in ’60s
BIGRAT
(BIcentennial Gamma RAy Telescope)
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CANGAROO-II telescope
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Upgraded in 2000 from
7m telescope completed
in 1999
114 x 80cm CFRP mirror
segments in parabola
(first plastic-base mirror
in the world!)
Focal length 8m
Alt-azimuth mount
552ch imaging camera
Charge and timing
electronics
(March 2000)
Tanimori et al., ICRC 1999
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CFRP mirror & tuning system
80cm, 5.5kg
Kawachi et al., Astropart.Phys. 14, 261 (2001)
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CANGAROO-II camera
3 FOV
 R4124UV
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(Hamamatsu)
0.115 pixel
 Lightguide
 16PMTs/module
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CANGAROO-II Electronics
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CANGAROO-II & -III
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Woomera: 2004 March
T2
T4
T3
T1
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Basic specifications of telescopes
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Location:
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114 80cm FRP mirrors
(57m2, Al surface)
8m focal length
Alt-azimuth mount
Camera:
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3106’S, 13647’E
160m a.s.l.
Telescope:
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T2
T1: 552ch (2.7 FOV)
T2,T3,T4: 427ch (4 FOV)
Electronics:
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TDC+ADC
Mori et al., Snowbird WS (1999)
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GFRP mirrors and tuning system
Tuning using star images
via a CCD camera
Before
tuning
After
tuning
2.0
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Ohishi et al., ICRC 2003
Spot size
T4
Y (vertical)
0.7
Point Spread
Function (FWHM)
T1: 0.20
T2: 0.21
T3: 0.14
T4: 0.16
(measured at construction time)
Image of a star
on camera
observed by a
CCD camera
X (horizontal)
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CANGAROO-III camera
R3479 (Hamamatsu)
FOV
Num.of pixel
Weight
Size of PMT
Pixel arrangement
HV polarity
HV supply unit
Lightguide (T1/T234)
T1
T2,T3,T4
3
4
552
427
~110kg
~110kg
½”
¾”
square
hexagonal
negative
positive
1ch/16 PMTs
1ch/1 PMT
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PMT gain uniformity and linearity
Kabuki et al., Nucl. Instr. Meth. A500, 318-336 (2003)
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Lightguide design
Winstone cone cross section
Efficiency vs. incident angle
Kajino et al., ICRC2001
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High voltage control & monitor
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Camera calibration
Blue LED flasher at
the reflector center
Blue LED flasher in
the camera box
Patterned
screen
Yamaoka et al., ICRC2003
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CANGAROO-III Electronics (1)
Kubo
et al.,
ICRC
2003
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CANGAROO-III Electronics (2)
Discriminator and
summing module (DSM)
Trigger logic
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CANGAROO-III Electronics (3)
ADC linearity
Single photoelectron spectrum
measured with DSM and ADC
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Telescope control
Telescope control unit
GPS
Position data
(every
100ms)
RS232C
Position
command
(alt-azimuth)
Driving
control
PC
Remote command/position data/NTP
Local area network
Hayashi et al., ICRC2003
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Star tracking
Star position error observed by a CCD camera
T3
PMT size
RMS deviation
0.013 degree
CCD X-axis (degree)
Hear
Kiuchi’s
talk!
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Construction of CANGAROO-III
1999
6
2001
3
2003
2002
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2004
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4-telescope stereo
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2000
T1
T2
T3
T4
: Construction
: Observation start
: Expansion to 10m
: Observation
: Tuning
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Sample of 4-fold stereo events
Data:
2004
March
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Global trigger system
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Each telescopes triggered
independently
Now: “hardware stereo”
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d
Before: “software trigger”
100m
Requires at least 2 telescopes
If no coincidence  Reset
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t=d/c < 500ns
variable
Dead time 1/100
150m
650ns
Opt.fiber
Trigger
Trigger
Coincidence
Event
number
Telescopes
Telescopes
Opt.fiber
Turnaround
~2.5s
Wait time
~5s
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Effect of global triggers
without global trigger
with global trigger
without global trigger
hadron
muon
with global trigger
Length/size
Muon events are removed!
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Beyond CANGAROO-III
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In the near future
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Improvement of old T1 and others
In the long range
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No unified plan yet…
Started brainstorming, technical and physical
considerations…
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Where should we go?
Lower
Energy
Wider
coverage
Large
reflector/
high
altitude
Wide
FOV
camera
Higher
Energy
Higher
sensitivity
Large
effective
area
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A case study: array of telescopes
How to achieve
large effective area
in modest cost?
 Large span array
with wide cameras?
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SPAN
Yoshikoshi et al. Paleiseau WS (2005)
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Lateral distribution of light
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Tail is extended beyond 150m!
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Array span vs. effective area
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6 FOV camera
Gamma-ray energy:
100 GeV, 1 TeV, 10
TeV
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Summary
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CANGAROO-III is a system of 10m imaging
Cherenkov telescope build by Japanese-Australian
collaboration.
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We have been carrying out 4-telescope stereo
observations of sub-TeV gamma-rays since 2004
March. Now we have incorporated a global trigger
system to reduce muons.
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We are studying the next-generation telescopes.
One option could be a large-span array of
telescopes to increase the effective area.
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End
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Stereo observation
Angular resolution
0.25deg  0.1 deg
Energy resolution
30%  15%
Better S/N (no local muons)
Intersection
point
Target
(qx, qy)
q2
Entries/bin
q2 distribution
(Simulation)
0
= qx
2+
qy
2
0.25
q2 [deg2]
0.5
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Unfortunate situation for the Crab
Showers
from the
Crab
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The oldest T1 has
higher energy
threshold and bad
efficiency for
stereo observation
Only T2/T3/T4 are
used for stereo
analysis
Stereo baseline
becomes short for
the Crab
observation at
large zenith angles
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Large zenith angle observation of the Crab
Higher energy threshold ~1TeV
Narrower
Bad intersection accuracy
Entries/bin
Far coresmall anglebad accuracy
0
h30
h60
90
q
180
Accept 15<q<165 only
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Team “A”
Crab signal (1)
(simple square cuts)
Nov 2003
(On-Off)/bin
Entries/bin
On
Off
q2 [deg2]
Sigma : 6.19
Excess : 25842 event
Angular Resolution : 0.16 (HWHM)
q2 [deg2]
•T2 & T3
•ON 7.5hr
•OFF 7.0hr
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Crab signal (2)
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Significance map
Team “A”
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Differential flux
Angular resolution for the Crab (h~35)
~0.17 (RA) / 0.14  (Decl)
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