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Brenda Dingus8 Nov 2007
HAWC HAWC (High Altitude Water Cherenkov)(High Altitude Water Cherenkov) A WideA Wide--Field GammaField Gamma--Ray TelescopeRay Telescope
Brenda DingusBrenda DingusLos Alamos National LabLos Alamos National Lab
Brenda Dingus8 Nov 2007
ComplementarityComplementarity of TeV Gammaof TeV Gamma--Ray Detectors Ray Detectors Imaging Air Cherenkov Telescopes Extensive Air Shower Arrays
Energy RangeEnergy Range 0.050.05--50 TeV50 TeV 0.10.1--100100 TeVTeV
AreaArea >10>1044 mm22 >10>1044 mm22
Background RejectionBackground Rejection >99%>99% >95%>95%
Angular ResolutionAngular Resolution 0.050.05oo 0.30.3--0.70.7oo
Energy ResolutionEnergy Resolution ~15%~15% ~50%~50%
ApertureAperture 0.003 0.003 srsr 2 2 srsr
Duty CycleDuty Cycle 10%10% 95%95%
IACTs EAS arrays
Brenda Dingus8 Nov 2007
HAWC Detector DesignHAWC Detector Design
From Milagro to HAWC:From Milagro to HAWC:•• Increase Altitude to 4100 m from Increase Altitude to 4100 m from
2650 m 2650 m •• Increase Area to 22,000 mIncrease Area to 22,000 m2 2 from from
4,000 m4,000 m2 2 (top layer) or 2,200m(top layer) or 2,200m2 2
(bottom layer)(bottom layer)•• Reuse 900 Milagro PMTs and Reuse 900 Milagro PMTs and
front end electronics front end electronics •• Cost $7.4MCost $7.4M•• HAWC 10 HAWC 10 –– 15 x Sensitivity of 15 x Sensitivity of
Milagro:Milagro:–– HAWC: HAWC: Detect Crab in ~ 1 day (5Detect Crab in ~ 1 day (5σσ))–– Milagro: Milagro: Detects Crab in 3 monthsDetects Crab in 3 months
e μ γ
Brenda Dingus8 Nov 2007
HAWC Detector DesignHAWC Detector Design
• 900 water tanks• Tanks are 5 meter
diameter and 4.3 meter deep
• Tanks cost $4.1k each (inc. shipping)
• One 8” PMT/tank• Tank array covers
area of 150m x 150m with 78% coverage
DAQ trailer
Road
HAWC Tank Array in GEANT 4
Brenda Dingus8 Nov 2007
Tanks Tanks vsvs PondPond•• Less expensiveLess expensive•• Build incrementallyBuild incrementally
–– Develop & debug as we Develop & debug as we are buildingare building
–– Within 2 yrs HAWC will Within 2 yrs HAWC will have 4x Milagro have 4x Milagro sensitivitysensitivity
•• Expandable & Expandable & upgradeableupgradeable
GEANT4 SimulationMuon (thinned 1/50) produces up to 100s of pes depending on impact parameter
100 MeV γ−ray (thinned 1/200) produces 1pe/60 MeV independent of impact parameter
See Poster by John Pretz
Brenda Dingus8 Nov 2007
Site Location is Sierra Site Location is Sierra NegraNegra, Mexico, Mexico• 4100 m above sea level• Easy Access
• 2 hr drive from Puebla • 4 hr drive from Mexico City
• Existing Infrastructure• Few km from the US/Mexico
Large Millimeter Telescope• Power, Internet, Roads• Sierra Negra Scientific
Consortium of ~7 projects • Excellent Mexican
Collaborators• ~15 Faculty at 7 institutions
have submitted proposal to CONACYT for HAWC
• Experience in HEP, Auger, and astrophysics (including TeV)
See Poster by Alberto Carramiñana
Brenda Dingus8 Nov 2007
HAWC CollaborationHAWC CollaborationUSA:
Los Alamos National Laboratory Brenda Dingus, John Pretz, Gus SinnisUniversity of Maryland Jordan Goodman, Andrew Smith, Greg SullivanUniversity of Utah Dave Kieda, University of New Mexico John MatthewsMichigan State University Jim LinnemannPennsylvania State University Ty DeYoungNASA/Goddard Space Flight Center Julie McEneryUniversity of New Hampshire James RyanUniversity of California, Irvine Gaurang Yodh
Mexico:Instituto Nacional de Astrofísica Óptica y Electrónica (INAOE)
Alberto Carramiñana, Eduardo MendozaUniversidad Nacional Autónoma de México (UNAM)
Instituto de Astronomía: Magdalena González, Dany Page, William Lee, Hector Hernández, Deborah Dultzin, Erika BenitezInstituto de Física: Arturo Menchaca, Rubén Alfaro, Andres Sandoval, Ernesto BelmontInstituto de Ciencias Nucleares: Lukas Nellen, G. Medina-TancoInstituto de Geofísica: José Valdés Galicia, Alejandro Lara
Benemérita Universidad Autónoma de PueblaHumberto Salazar, Oscar Martínez, Cesar Álvarez, Arturo Fernández
Universidad Michoacana de San Nicolás de Hidalgo Luis VillaseñorCINVESTAV Arnulfo ZepedaUniversidad de Guanajuato
David Delepine, Gerardo Moreno, Marco Reyes, Luis Ureña, Victor Migenes
Brenda Dingus8 Nov 2007
HAWC Sensitivity is HAWC Sensitivity is 15x Better than 15x Better than MilagroMilagro’’ss
e μ γ
(a)(a) Larger Effective Area at Larger Effective Area at Lowest EnergiesLowest Energies
(b)(b) Better Angular Better Angular ResolutionResolution
(c)(c) Improved Background Improved Background RejectionRejection
=> 10=> 10--15 x 15 x improvement in flux improvement in flux sensitivitysensitivity
=> (10=> (10--15)15)22 x faster to x faster to observe same flux observe same flux
(a)
(b)
(c)
100 GeV 1 TeV 10TeV 100 TeV
100 GeV 1 TeV 10TeV 100 TeV
100 GeV 1 TeV 10TeV 100 TeV
Had
ron
Effi
cien
cy
Ang
. Res
. (de
g)
E
ff. A
rea
(m2 )
Brenda Dingus8 Nov 2007
• Gammas have NARROW lateral distribution of electrons
• Protons have BROAD lateral distribution of muons
Lateral Distribution of Extensive Air ShowersLateral Distribution of Extensive Air Showers
Brenda Dingus8 Nov 2007
Gamma/Hadron SeparationGamma/Hadron Separation
Gam
mas
Prot
ons
30 GeV 70 GeV 230 GeV
20 GeV 70 GeV 270 GeVSize of HAWC
Size of Milagro deep layer
Energy Distribution at ground level
Rejection factor ~ e-<μ>
Brenda Dingus8 Nov 2007
Background Rejection in MilagroBackground Rejection in MilagroProton MCProton MC Proton MCProton MC
DataData DataDataγγ
MCMC γγ
MCMC
Hadronic showers contain penetrating component: μ’s & hadrons
– Cosmic-ray showers lead to clumpier bottom layer hit distributions– Gamma-ray showers give smooth hit distributions
Brenda Dingus8 Nov 2007
Milagro Background Rejection (ContMilagro Background Rejection (Cont’’d)d)
( )mxPE
nFitfOut+fTop=A ∗4
mxPE: maximum # PEs in bottom layer PMT
fTop: fraction of hit PMTs in Top layer
fOut: fraction of hit PMTs in Outriggers
nFit: # PMTs used in the angle reconstruction
S/B increases with increasing AS/B increases with increasing A4 4 so so analysis weights events by S/B as analysis weights events by S/B as determined by the Adetermined by the A44 value of the value of the eventevent
Background Rejection ParameterBackground Rejection Parameter
Brenda Dingus8 Nov 2007
E F(>E
) (TeV/cm
2s)
Sensitivity to CrabSensitivity to Crab--like (like (dN/dEdN/dE=E=E--2.62.6) Point Source ) Point Source
GeV
•• HESS/VERITAS,HESS/VERITAS, MAGICMAGIC, , Whipple, Whipple, CTA CTA sensitivity in sensitivity in 50 hours, (~0.2 50 hours, (~0.2 srsr/year)/year)
•• GLASTGLAST sensitivity sensitivity in 1 year (4in 1 year (4ππ
srsr))
•• HAWC, HAWC, MilagroMilagro, , sensitivity in sensitivity in 1(solid) and 5 1(solid) and 5 (dashed) years (dashed) years (2(2ππ
srsr))
•• HAWC will do HAWC will do better for hard & better for hard & diffuse sourcesdiffuse sources
4 TeV6 TeV
Brenda Dingus8 Nov 2007
HAWCHAWC’’ss Field of ViewField of View
= 2.6 π sr
= 1.8 π
sr
Brenda Dingus8 Nov 2007
HAWC Science ObjectivesHAWC Science Objectives
•• Constrain the Constrain the origin of cosmic raysorigin of cosmic rays via via HAWCHAWC’’ss observations of observations of γγ--rays up to 100 TeVrays up to 100 TeV from discrete sources and the Galactic plane.from discrete sources and the Galactic plane.
•• Probe Probe particle accelerationparticle acceleration in extreme in extreme magnetic and gravitational fields via magnetic and gravitational fields via HAWCHAWC’’ss observations of transient TeV observations of transient TeV sourcessources, such as gamma ray bursts and , such as gamma ray bursts and supermassivesupermassive black holes.black holes.
•• Explore Explore new TeV physicsnew TeV physics via via HAWCHAWC’’ss unbiased sky surveyunbiased sky survey with a detection with a detection threshold of ~30 threshold of ~30 mCrabmCrab in two years. in two years.
Brenda Dingus8 Nov 2007
CrabNebula
Mrk 421
Cygnus Region
HAWC’s science objectives build on the discoveries of Milagro
Brenda Dingus8 Nov 2007
Distribution of Excesses in the Galactic Plane
cut level
CrabNebula
Mrk 421
•• 6.5 year data set (July 20006.5 year data set (July 2000--January 2007)January 2007)•• Weighted analysis using A4 parameterWeighted analysis using A4 parameter
–– Best data from 2004 on with outriggersBest data from 2004 on with outriggers•• Crab nebula 15 Crab nebula 15 σσ•• Galactic plane clearly visibleGalactic plane clearly visible
Cygnus Region
Brenda Dingus8 Nov 2007
Abdo, et al. ICRC 2007
5.8 σ
4.5 σ
3.8 σ
C1 J2044+36
C2 J2031+33
MGRO J2031+41MGRO J2019+37
Tibet Excess
C3 J0634+17
Geminga
108 106
C4 J2226+60 EGRETE. Ona-Wilhelmi, et al., ICRC 2007
Brenda Dingus8 Nov 2007
Abdo, et al. ApJ Lett 2007
GeV Sources Emit TeV GammaGeV Sources Emit TeV Gamma--RaysRays
•• Milagro has discoveredMilagro has discovered 3 new sources3 new sources & & 4 candidates 4 candidates in the Galaxy.in the Galaxy.•• 5/7 of these TeV sources have GeV counterparts.5/7 of these TeV sources have GeV counterparts. Only 13 GeV Only 13 GeV
counterparts in this region counterparts in this region -- excluding Crab. excluding Crab. Probability = 3x10Probability = 3x10--66
•• HAWC + GLAST observations survey the sky from 100 MeV to 100 TeVHAWC + GLAST observations survey the sky from 100 MeV to 100 TeV
LS I + 61 303
HESS J0632+057
IC443
H H
Brenda Dingus8 Nov 2007
Milagro Extension of TeV spectrum of Milagro Extension of TeV spectrum of MGRO J1908+06 MGRO J1908+06 -- PreliminaryPreliminary
60 90
Median energy for this angle and α=-2.0 is 50 TeV Cut on A4> 4 & 9 gives median E of 60 and 90 TeV
Brenda Dingus8 Nov 2007
•• Shower Fluctuations Shower Fluctuations Dominate Energy Dominate Energy ResolutionResolution
•• Higher Altitude of HAWC Higher Altitude of HAWC increases # of particles increases # of particles by ~6x by ~6x
•• Ability to measure a high Ability to measure a high energy cut off is a energy cut off is a combination of the combination of the energy resolution AND energy resolution AND the statistical error in the the statistical error in the fluxflux
HAWC Energy ResolutionHAWC Energy Resolution
Brenda Dingus8 Nov 2007
HESS J1616-5080.2 Crab @ 1 TeV α=-2.3
Highest energy ~20 TeV
Brenda Dingus8 Nov 2007
HESS J1616-5080.2 Crab @ 1 TeV α=-2.3
Highest energy ~20 TeV
Simulated HAWC data for 1 year with no cutoff
Brenda Dingus8 Nov 2007
HESS J1616-5080.2 Crab @ 1 TeV α=-2.3
Highest energy ~20 TeV
Simulated HAWC data for 1 year with 40 TeV exponential cutoff
Brenda Dingus8 Nov 2007
Sensitivity vs. Angular ExtentSensitivity vs. Angular Extent
Sextended ≈ Spointσ source
σ detector
σEAS ~0.5o σIACT ~0.1o
EAS large fov of 2 sr:
Entire source & background simultaneously observable
Background well characterized
Brenda Dingus8 Nov 2007
Galactic Diffuse EmissionGalactic Diffuse Emission•• Probing cosmic ray origin Probing cosmic ray origin
requires distinguishing requires distinguishing between electron and between electron and hadron produced hadron produced γγ--raysrays
•• Hadrons are correlated Hadrons are correlated with matter density and with matter density and the flux is strongly the flux is strongly constrained by direct constrained by direct cosmic ray observationscosmic ray observations
•• Flux from electrons is Flux from electrons is less constrained, but less constrained, but must decrease at highest must decrease at highest energies due to Kenergies due to K--N N effectseffects
Hadronic Pion Decay
Electron Inverse Compton Scattering
GALPROP Conventional (solid) and Optimized (dashed) Models
Milagro Observation
Brenda Dingus8 Nov 2007
Milagro Observations of Milagro Observations of Galactic Diffuse EmissionGalactic Diffuse Emission
Below HorizonCygnus Region
GALPROP (optimized)
Sources SubtractedHuntemeyer, et al. ICRC 2007
2.7x
GA
LPR
OP
1.5x
GA
LPR
OP
Cygnus Region with Matter Density Contours overlaying Milagro Significance
Source Subtracted Longitude Profile(see details in poster by Petra Huntemeyer)
Brenda Dingus8 Nov 2007
Extragalactic Science: HAWC & TransientsExtragalactic Science: HAWC & Transients
GLAST and HAWC sensitivity for a source of spectrumdN/dE=KE-2
z=0 no E cutoffz=0.1 Eexp ~700GeVz=0.3 Eexp ~260GeVz=0.5 Eexp ~170GeV10
-12
10-1
010
-810
-6
TeV AGN flares
GRB <1 MeV
•• AGN and GRBs have bright flaresAGN and GRBs have bright flarese.g. PKS J2155e.g. PKS J2155--304 (z=0.117) flared to 50x quiescent flux in one hour 304 (z=0.117) flared to 50x quiescent flux in one hour with with dN/dEdN/dE=kE=kE--3.53.5 which would give which would give 6 6 σσ
in HAWCin HAWC
Brenda Dingus8 Nov 2007
AGNsAGNs• HAWC will obtain duty factors and notify multiwavelength observers of
flaring AGN in real time.• Milagro has observed 7yr lightcurve of Mrk 421• HAWC’s increased sensitivity would result in ~10x smaller error bars
and have similar error bars on hour time scale rather than 64 days
Mila
gro
-Eve
nts/
day
AS
M F
lux
cts/
s
MJD - 500001/1/2000 1/1/2001 1/1/2002 1/1/2003 1/1/2004 1/1/2005 1/1/2006 1/1/2007
Milagro and XTE ASM 7 yr lightcurve of Mrk 421 (Smith et al. ICRC 2007)
Crab Flux
Brenda Dingus8 Nov 2007
GRBsGRBs•• Milagro searches data within few seconds for Milagro searches data within few seconds for
short duration transients and sends alerts to short duration transients and sends alerts to GCN, but has found no significant emissionGCN, but has found no significant emission
•• HAWCHAWC’’ss low energy response allows dimmer low energy response allows dimmer GRBs at more distant GRBs at more distant redshiftsredshifts to be observed to be observed
Brenda Dingus8 Nov 2007
HAWC sample GRB HAWC sample GRB lightcurvelightcurve
•• High Energy cut off High Energy cut off could occur due to could occur due to absorption in GRB absorption in GRB or in transit via EBL or in transit via EBL interaction.interaction.
•• Measurements of Measurements of lightcurvelightcurve reveal reveal information about information about progenitor and progenitor and constrains Lorentz constrains Lorentz invarianceinvariance..
HAWC lightcurve of a bright GRB (1e-4 ergs/cm2 fluence). Weaker burst counts scale with fluence.
Brenda Dingus8 Nov 2007
Surveying the TeV SkySurveying the TeV Sky
•• Discovery PotentialDiscovery Potential•• Many Classes of Potential TeV Sources Many Classes of Potential TeV Sources
–– Extended SourcesExtended Sources•• Dark Matter, Galaxy clusters, AGN Pair Halos, Dark Matter, Galaxy clusters, AGN Pair Halos,
Molecular Clouds, . . .Molecular Clouds, . . .
–– Variable SourcesVariable Sources•• Compact Binaries, Compact Binaries, MicroquasarMicroquasar Flares, Solar Flares, Solar
Energetic Particles, . . .Energetic Particles, . . .
Brenda Dingus8 Nov 2007
MilagroMilagro’’s Unexpected s Unexpected Cosmic Ray Anisotropy ObservationCosmic Ray Anisotropy Observation• Anisotropy on 10 deg size scale with a fractional excess
of 7e-4 above the cosmic ray background (15 σ)• Excess is not gamma rays, but charged cosmic rays (5 σ)• Largest excess is not consistent with the locally
measured cosmic ray energy spectrum (4 σ), but is harder with a cut off of ~10 TeV
• Explanations are difficult because the gyroradius of a 10 TeV proton in a 1 μG field is 0.01 parsecs
See Poster by Gary Walker
Brenda Dingus8 Nov 2007
•• Milagro technique worksMilagro technique works–– Discovery of diffuse TeV gamma rays from Galactic plane & CygnusDiscovery of diffuse TeV gamma rays from Galactic plane & Cygnus regionregion–– Discovery of new Galactic TeV sources Discovery of new Galactic TeV sources –– Demonstration of longDemonstration of long--term multiterm multi--wavelength AGN monitoringwavelength AGN monitoring–– Unexpected TeV CosmicUnexpected TeV Cosmic--ray anisotropy observedray anisotropy observed
•• With HAWC Large improvements are possible With HAWC Large improvements are possible –– 1010--15 times the sensitivity of Milagro 15 times the sensitivity of Milagro –– ~5 ~5 σσ//√√day on the Crabday on the Crab–– 3% of Crab flux sensitivity over entire hemisphere (after 2 year3% of Crab flux sensitivity over entire hemisphere (after 2 year operation)operation)
•• Scientific CapabilitiesScientific Capabilities–– Highest energies Highest energies –– Extended sourcesExtended sources–– Galactic diffuse emissionGalactic diffuse emission–– TeV transients TeV transients –– Unbiased Sky surveyUnbiased Sky survey
ConclusionsConclusions
Brenda Dingus8 Nov 2007
TeV TeV γγ
Rays: Rays: New Window on the SkyNew Window on the Sky
TeV gamma rayHESS
Milagro