The Milagro Gamma-The Milagro Gamma-Ray ObservatoryRay Observatory

By Timothy By Timothy WillettWillett

CROP: Roncalli DivisionCROP: Roncalli Division

Milagro’s Etymology and Milagro’s Etymology and LocationLocation

MILAGROMILAGRO stands for stands for MMultiple ultiple IInstitution nstitution LLos os AAlamos lamos GGamma amma RRay ay OObservatorybservatory

The word “milagro” is The word “milagro” is also Spanish for also Spanish for “miracle”“miracle”

The detector array is The detector array is located in the Jemez located in the Jemez mountains near Los mountains near Los Alamos, New MexicoAlamos, New Mexico

Altitude: 2,630m Altitude: 2,630m (8690ft) above sea (8690ft) above sea levellevel

<http://www.physics.nyu.edu/~am3/images/<http://www.physics.nyu.edu/~am3/images/hdrsite.jpg>hdrsite.jpg>

MilagroMilagro

<Umdgrb.umd.edu<Umdgrb.umd.edu>>

What is Milagro?What is Milagro?

Milagro is a large pool of water filled with Photo Milagro is a large pool of water filled with Photo Multiplier TubesMultiplier Tubes

The pond is 80m x 60m x 8mThe pond is 80m x 60m x 8m The pond is lined on the bottom, covered on the The pond is lined on the bottom, covered on the

top, and filled with watertop, and filled with water

http://www.lanl.gov/milagro/http://www.lanl.gov/milagro/Inside MilagroInside Milagro

PMTs are PMTs are suspended 1.5 suspended 1.5 and 6.5 meters and 6.5 meters below the below the water surfacewater surface

The full The full detector, detector, completed in completed in fall of 1998, fall of 1998, includes 723 includes 723 PMTsPMTs

<http://www.physics.nyu.edu/~am3/<http://www.physics.nyu.edu/~am3/

milagro.html>milagro.html>

More Inside MilagroMore Inside Milagro

Comparison of ACT : EASAComparison of ACT : EASA An Air Cherenkov Telescope (ACT) An Air Cherenkov Telescope (ACT)

is a system of mirrors that focuses is a system of mirrors that focuses Cherenkov light into PMTs to learn Cherenkov light into PMTs to learn more about cosmic ray showersmore about cosmic ray showers

They can only be operated at nightThey can only be operated at night

An Extensive Air Shower Array An Extensive Air Shower Array (EASA) is characterized by (EASA) is characterized by sparsely positioned detectors sparsely positioned detectors (typically plastic scintillators) (typically plastic scintillators) which emit light when a cosmic which emit light when a cosmic ray passes through themray passes through them

They can operate under all They can operate under all conditions, night or dayconditions, night or day

Each type of cosmic ray Each type of cosmic ray detection has its own detection has its own advantages and disadvantagesadvantages and disadvantages

Left: ACT Right: Left: ACT Right: EASAEASA

<http://www.lanl.gov/milagro/detecting.shtml><http://www.lanl.gov/milagro/detecting.shtml>

Chart of ComparisonChart of Comparison

Air Cherenkov Telescope Extensive Air Shower ArrayEnergy Threshold Low (<200 GeV) High (>50 TeV)Background Rejection Excellent (>99.7%) Moderate (>50%)Field of View Small (~2o) Large (>45o)Duty Cycle (On time) Low (5-10%) High (>90%)

Milagro was designed to combine the low Milagro was designed to combine the low energy threshold of ACTs with the large energy threshold of ACTs with the large field of view and high duty cycle of EAS field of view and high duty cycle of EAS arraysarrays

Milagro’s Purpose and Milagro’s Purpose and GoalsGoals

Search for gamma-ray Search for gamma-ray bursts emitting TeV gamma bursts emitting TeV gamma raysrays

Search for nearby active Search for nearby active galactic nuclei (AGN)galactic nuclei (AGN)

Search the Northern Search the Northern Hemisphere sky for sources Hemisphere sky for sources of TeV gamma raysof TeV gamma rays

Search for primordial black Search for primordial black holes (PBH)holes (PBH)

Study the properties of the Study the properties of the solar magnetic fieldsolar magnetic field

<http://umdgrb.umd.edu/cosmic/milagro.html><http://umdgrb.umd.edu/cosmic/milagro.html>Simulated Shower Hitting Simulated Shower Hitting

MilagroMilagro

So what makes Milagro So what makes Milagro new?new? This is a new type of detector: a water Cherenkov extensive This is a new type of detector: a water Cherenkov extensive

air shower arrayair shower array This is the first example of a large continuous pool being used This is the first example of a large continuous pool being used

as a gamma-ray telescopeas a gamma-ray telescope

Using Milagro, we Using Milagro, we can observe the can observe the Universe over 20 Universe over 20 order of order of magnitude in magnitude in photon energyphoton energy

Milagro is the Milagro is the first telescope first telescope capable of capable of continuously continuously monitoring the monitoring the Northern sky in Northern sky in this energy this energy range.range.<http://www.lanl.gov/<http://www.lanl.gov/

milagro/milagro/everyone.shtml>everyone.shtml>

Milagro BenefitsMilagro Benefits

The index refraction of water is much bigger The index refraction of water is much bigger than that of airthan that of air The number of Cherenkov photons per unit track is The number of Cherenkov photons per unit track is

greatergreater The Cherenkov light angle in water is 41The Cherenkov light angle in water is 41°, while it is °, while it is

only 1° in aironly 1° in air More Material into which the particles can bumpMore Material into which the particles can bump

<http://www.lanl.gov/milagro/concept.shtml><http://www.lanl.gov/milagro/concept.shtml>

In-Depth: Active Galactic In-Depth: Active Galactic NucleiNuclei

Active Galactic Nuclei Active Galactic Nuclei are believed to be are believed to be supermassive black supermassive black holes surrounded by holes surrounded by accretion disksaccretion disks

These “black holes” These “black holes” seem to emit beams seem to emit beams of high energy of high energy particlesparticles

These beams, or jets, These beams, or jets, are spewed are spewed perpendicular to the perpendicular to the diskdisk

<http://www.lanl.gov/milagro/physics.shtml><http://www.lanl.gov/milagro/physics.shtml>

Another look at AGNAnother look at AGN

<http://www.lanl.gov/<http://www.lanl.gov/milagro/milagro/physics.shtml>physics.shtml>

The GadgetsThe Gadgets Pond, Liner, and CoverPond, Liner, and Cover PMTs and anchor gridPMTs and anchor grid Cover inflation systemCover inflation system Lightning protection systemLightning protection system Water Purification and Water Purification and

Circulation ApparatusCirculation Apparatus Data Acquisition and Data Acquisition and

computer…stuffcomputer…stuff Environmental monitoring Environmental monitoring

systemsystem Computer Simulation Computer Simulation

SoftwareSoftware

PP

MM

TT

ss <http://www.physics.nyu.edu/~am3/milagro.html><http://www.physics.nyu.edu/~am3/milagro.html>

Nowadays at MilagroNowadays at Milagro

Publications in 2001 suggest activity still Publications in 2001 suggest activity still todaytoday

There is a collection of animations that There is a collection of animations that show the research Milagro has show the research Milagro has accomplished in a few short years:accomplished in a few short years:http://scipp.ucsc.edu/milagro/Animations/Pages/http://scipp.ucsc.edu/milagro/Animations/Pages/

MilAnimIndex/E200MeV.htmlMilAnimIndex/E200MeV.htmlhttp://scipp.ucsc.edu/milagro/Animations/Pages/http://scipp.ucsc.edu/milagro/Animations/Pages/MilAnimIndex/G2TeVBottom.htmlMilAnimIndex/G2TeVBottom.html

http://scipp.ucsc.edu/milagro/Animations/Pages/http://scipp.ucsc.edu/milagro/Animations/Pages/EASIndexPages/EASIndexG2TeVPart.htmlEASIndexPages/EASIndexG2TeVPart.html

George Mason UniversityGeorge Mason University Los Alamos National LaboratoryLos Alamos National Laboratory New York UniversityNew York University University of California, IrvineUniversity of California, Irvine University of California, RiversideUniversity of California, Riverside University of California, Santa CruzUniversity of California, Santa Cruz University of Maryland, College ParkUniversity of Maryland, College Park University of New Hampshire, DurhamUniversity of New Hampshire, Durham University of WisconsinUniversity of Wisconsin

<http://www.lanl.gov/milagro/<http://www.lanl.gov/milagro/collaboration.shtml>collaboration.shtml>

(Kinda Boring, But Important)(Kinda Boring, But Important)

What did I tell You?What did I tell You? Where the name comes from/locationWhere the name comes from/location What Milagro is and what it doesWhat Milagro is and what it does Comparison of ACTs and EASAsComparison of ACTs and EASAs Milagro’s purpose and goalsMilagro’s purpose and goals Why is Milagro new/what are benefits?Why is Milagro new/what are benefits? In-Depth: Active Galactic NucleiIn-Depth: Active Galactic Nuclei Gadgets they useGadgets they use Nowadays at Milagro (Animations)Nowadays at Milagro (Animations) CollaboratorsCollaborators I told you what I told youI told you what I told you <Timothy Willett><Timothy Willett>

BibliographyBibliography

http://scipp.ucsc.edu/milagro/Animations/http://scipp.ucsc.edu/milagro/Animations/AnimationIntro.htmlAnimationIntro.html

http://umdgrb.umd.edu/cosmic/http://umdgrb.umd.edu/cosmic/milagro.htmlmilagro.html

http://www.lanl.gov/milagro/http://www.lanl.gov/milagro/

http://www.physics.nyu.edu/~am3/http://www.physics.nyu.edu/~am3/milagro.htmlmilagro.html

(Who I stole my information (Who I stole my information and cool pictures from)and cool pictures from)