Synoptic TeV Telescopes
Results from Milagro
Plans for HAWC
Gus Sinnis
Los Alamos National Laboratory
Adelaide, Australia. December 2006
Milagro
• A Water Cherenkov detector.
• Reconstruct shower direction to 0.3-0.7o from
the timing shower front.
• Reject background by detecting penetrating
component of hadronic showers
• Field of view is ~2 sr
• Duty factor ~95%
• Trigger rate ~1700 Hz (6 Mbytes/sec)
Milagro Cross Section Schematic
e
m
g
8 meters
50 meters
80 meters
Gus Sinnis
Los Alamos National Laboratory
Adelaide, Australia. December 2006
Milagro with Outriggers
175 Outrigger tanks (Tyvek lined – water filled)
2.4m diameter, 1m deep
34,000 m2 enclosed area
Completed in May 2003
Gus Sinnis
Los Alamos National Laboratory
Adelaide, Australia. December 2006
Background Rejection in
Milagro
Hadronic showers contain penetrating
component: m’s & hadrons
– Cosmic-ray showers lead to
clumpier bottom layer hit
distributions
– Gamma-ray showers give
smooth hit distributions
g MC
Gus Sinnis
Proton MC
Proton MC
Data
Data
g MC
Los Alamos National Laboratory
Adelaide, Australia. December 2006
Background Rejection (Cont’d)
• Parameterize “clumpiness” of the
bottom layer hits
– Compactness C =
nb2
mxPE
• Require C > 2.5
• 50% gammas & 10% hadrons
• Sensitivity improved by 1.6
A4 =
 fTop + fOut  nFit
mxPE
• Require A4 > 3.0
• 20% gammas & 1% hadrons
• Sensitivity further improved by 1.4
mxPE:
maximum # PEs in bottom layer PMT
nb2:
# bottom layer PMTs with 2 PEs or more
fTop:
# fraction of hit PMTs in Top layer
fOut:
# fraction of hit PMTs in Outriggers
nFit:
# PMTs used in the angle reconstruction
Gus Sinnis
Los Alamos National Laboratory
Adelaide, Australia. December 2006
Spectral Determination
A4 is related to energy
2-20 TeV useful range
Gus Sinnis
Los Alamos National Laboratory
Parameterization of events
Adelaide, Australia. December 2006
Crab Spectrum
Exponential cut off energy is
Ec = 31.0 TeV (w/large error
bars)
Gus Sinnis
Los Alamos National Laboratory
Adelaide, Australia. December 2006
2006 (post-outrigger)
Milagro Sky Survey
Gus Sinnis
Cygnus Region
Los Alamos National Laboratory
MRK 421
Crab Nebula
Adelaide, Australia. December 2006
Significance
The Galactic Plane
GP diffuse excess clearly
visible from l=25° to l=90°
Cygnus Region shows
extended excess
FCygnus ~ 2 x Fcrab
120 square degrees
l (65,85), b (-3,3)
Gus Sinnis
Los Alamos National Laboratory
Adelaide, Australia. December 2006
The Cygnus Region



Contours are GALPROP
pion model
Crosses are EGRET
(unidentified) sources
TeV/matter correlation good
Chance noncorrelation 1.5x10-6

Brightest TeV Region
– MGRO J2019+37
– ~0.5 Crab @ 12 TeV
– Extent = 0.32 ± 0.12
deg.
– Coincident with 2
EGRET sources (unID)
• PWN G75.2 + 0.1
• Blazar (B2013+370)
– Energy Analysis in
progress
Flux @ 12.5 TeV= E2 dN/dE = (4.18 ± 0.52stat ± 1.26sys) x 10-10 TeV cm-2 s-1 sr-1
(excluding new source & assuming E-2.6)
~3.5 Crab in 180 sq. degree region
Gus Sinnis
Los Alamos National Laboratory
Adelaide, Australia. December 2006
Cygnus Region: Diffuse Gamma Rays
Strong & Moskalenko
GALPROP model of
Cygnus Region
Gus Sinnis
• Strong & Moskalenko
optimized model
Los Alamos National Laboratory
– Increase 0 and IC
component throughout
Galaxy
– Milagro 2-6x above
prediction (optimizedstandard models)
– Unresolved sources?
– Cosmic-ray
accelerators?
Adelaide, Australia. December 2006
Cygnus Region: Multi-wavelength
Radio Continuum (408MHz)
Atomic Hydrogen
Radio Continuum (2.5GHz)
Molecular Hydrogen
X-Ray
Gamma-Ray (100 MeV)
0.1 GeV
Gamma-Ray (10 TeV)
Milagro 10 TeV gamma-ray
Gus Sinnis
Los Alamos National Laboratory
Adelaide, Australia. December 2006
HAWC
High
Altitude
Water
Cherenkov
Telescope
g
A proposal to redeploy the Milagro PMTs
with Wider Spacing
at Higher Altitude
10-15 times more sensitive than Milagro
Gus Sinnis
Los Alamos National Laboratory
Adelaide, Australia. December 2006
HAWC Goals
• Complete hemisphere survey to 25 mCrab
– After 4 years
• Detailed map of Galactic diffuse emission
• Search for extended sources
• Detect AGN transients
– 4 Crab in 15 minutes
• Detect GRBs to 1/100 keV fluence
• Spectra to the highest energies (~100 TeV)
• Contemporaneous with GLAST, HESS,
VERITAS, & IceCube
Gus Sinnis
Los Alamos National Laboratory
Adelaide, Australia. December 2006
Altitude Effect
4100m
2600m
Difference between 2600m (Milagro) and 4100m:
~ 6x number of particles
~ 2-3x lower median energy
Gus Sinnis
Los Alamos National Laboratory
Adelaide, Australia. December 2006
Milagro
Detector Layout
HAWC
Milagro:
450 PMT (25x18) shallow (1.4m) layer
273 PMT (19x13) deep (5.5m) layer
175 PMT outriggers
HAWC:
900 PMTs (30x30)
5.0m spacing
Single layer with 4m depth
Instrumented Area:
PMT spacing:
Total Area:
m det Area:
Instrumented Area:
PMT spacing:
Total Area:
m det Area:
Gus Sinnis
~40,000m2
2.8m
3500m2
2200m2
Los Alamos National Laboratory
22,500m2
5.0m
22,500m2
22,500m2
Adelaide, Australia. December 2006
6m
Milagro: 2 layers at depths
1.4m – “Air Shower” Layer
6.0m – “Muon” Layer
1.4 m
Detector Layout
2.8 m
4m
HAWC: Single intermediate layer
Opaque curtains between cells
Gus Sinnis
Los Alamos National Laboratory
5m
Adelaide, Australia. December 2006
Curtains
•
HAWC single muon rate = ~1 MHz
•
Install curtains to optically isolate the PMTs.
•
Avoid triggering on single muons
•
Intrinsic Gamma hadron separation
Gus Sinnis
Los Alamos National Laboratory
Adelaide, Australia. December 2006
HAWC Trigger Rate
• Multiplicity trigger at ~80 PMTs gives same CR
trigger rate as Milagro at 50 PMTs
• Much higher Gamma-ray rate.
Gamma-Ray Rate
HAWC
Milagro
Gus Sinnis
Los Alamos National Laboratory
Adelaide, Australia. December 2006
Angular Resolution
s = ~0.4 deg
nTrigger = 50 PMTs
Gus Sinnis
s = ~0.25 deg
nTrigger = 200 PMTs
Los Alamos National Laboratory
Adelaide, Australia. December 2006
Gamma/Hadron Separation
70 GeV
230 GeV
Gammas
30 GeV
Size of HAWC
70 GeV
270 GeV
Protons
20 GeV
Size of Milagro
deep layer
Gus Sinnis
Energy Distribution at ground level
Los Alamos National Laboratory
Adelaide, Australia. December 2006
Gamma/Hadron Separation
Circles are EM particles > 1 GeV
Circles are m’s & hadrons > 1 GeV
Circles are 30m radius (~area of Milagro bottom layer)
Gus Sinnis
Los Alamos National Laboratory
Adelaide, Australia. December 2006
Gamma/Hadron Separation
nHit/cxPE>5.0
Eff g
= 56%
Eff CR = 1.5%
nHit/cxPE>5.0
Eff g
= 34%
Eff CR = 3%
Q Factor (sig/√bg)
HESS
eg = 56% -> 28%
eCR= 3% -> 0.4%
(shape only)
Gus Sinnis
Cuts
soft hard
HAWC
2.0
4.5
HESS
3.2
4.4
Los Alamos National Laboratory
Adelaide, Australia. December 2006
Effective Area
Gamma Area: q<30o
nTop/cxPE>5.0
200 PMT Trigger
80 PMT Trigger
20 PMT Trigger
Dq<1.0O
Detector
Size
Area of
GLAST
Gus Sinnis
Los Alamos National Laboratory
Adelaide, Australia. December 2006
HAWC Point Source Sensitivity
Significance from
EGRET
Crab transit (4 hr)
~5 s
Crab 1 year
~100 s
Energy Resolution
~30% above
median
Angular Resolution
0.25O-0.5O
GLAST
S/B (hard cuts) ~ 1:1 for Crab
Single transit: 20 excess / 25 bkg
Q (sig/√bg) (HAWC/Milagro) = 15
Gus Sinnis
Los Alamos National Laboratory
Adelaide, Australia. December 2006
Sensitivity vs. Source Spectrum
Gus Sinnis
Los Alamos National Laboratory
Adelaide, Australia. December 2006
Sensitivity vs. Source Size
Gus Sinnis
Los Alamos National Laboratory
Adelaide, Australia. December 2006
Sky Surveys
Gus Sinnis
Los Alamos National Laboratory
Adelaide, Australia. December 2006
GRB Sensitivity
Milagro
HAWC
Fluence Sensitivity to 10s GRB.
Both Milagro and HAWC can “self trigger” and generate alerts in real time.
GRB rate in FOV ~100 GRB/year (BATSE rate)
Gus Sinnis
Los Alamos National Laboratory
Adelaide, Australia. December 2006
Pond Design
•
•
•
•
•
Fiducial volume: 150m x 150m x 4m
Actual size: 170m x 170m x 6m
1:1 slope at perimeter
6 m depth to allow for 4m over PMTs.
Total volume: 115 Ml
170m
4.5-5.0 m
6m
150m
Gus Sinnis
Los Alamos National Laboratory
Adelaide, Australia. December 2006
Building Construction
•
Prefabricated steel building
– Components manufactured
at factory.
– Shipped to site (~9 trucks)
– Beams bolted not welded.
– Cost ~1.5M$ (not installed)
•
•
•
Building installation ~400 k
Pond excavation ~300 k
Liner cost ~600 k
Total facility cost ~3.5 M
Total Cost ~5.2 M
Gus Sinnis
162m
Los Alamos National Laboratory
162m
Adelaide, Australia. December 2006
YBJ Laboratory – Tibet, China
Elevation: 4300m
Latitude: 30O 13’ N
Longitude: 90O 28’ E
Tibet Air Shower Array
Lots of space.
Available power.
Available water.
Gus Sinnis
Los Alamos National Laboratory
Adelaide, Australia. December 2006
Sierra Negra, Mexico
•1 km
•N
•1
•2
•3
•LMT
Elevation = 4100m or 4300m
Latitude = 19O 00’N
Longitude = 97O 17’ W
Gus Sinnis
Los Alamos National Laboratory
Adelaide, Australia. December 2006
HAWC Status and Timeline
• A proposal for a total project cost ~$5M has
been submitted by the US groups to NSF
– A proposal will be sent to DoE
– Mexican Collaborators have submitted a proposal to
their funding agency
• A final site decision will be made this year
• If approved:
– Next year we will do site specific design
– Start construction in 2008
– Complete construction and start data taking in 2010
Gus Sinnis
Los Alamos National Laboratory
Adelaide, Australia. December 2006
Conclusion
• Milagro has made significant discoveries:
– Discovery of diffuse TeV gamma rays from the Galactic plane
– Discovery of diffuse TeV gamma rays from the Cygnus region
– Discovery of a new extended TeV source in the Cygnus region
• HAWC can attain high sensitivity over an entire
hemisphere
– ~15 times the sensitivity of Milagro
– ~5 sigma/day on the Crab
– 30 mCrab sensitivity over entire
hemisphere
– Unsurpassed sensitivity to extended
sources
– Unique TeV transient (AGN/GRB)
detector
– Can be built quickly @ low cost
Gus Sinnis
Los Alamos National Laboratory
Adelaide, Australia. December 2006