The Milagro Gamma-Ray Observatory By Timothy Willett CROP: Roncalli Division

Milagro’s Etymology and Location MILAGRO stands for Multiple Institution Los Alamos Gamma Ray Observatory MILAGRO stands for Multiple Institution Los Alamos Gamma Ray Observatory The word “milagro” is also Spanish for “miracle” The word “milagro” is also Spanish for “miracle” The detector array is located in the Jemez mountains near Los Alamos, New Mexico The detector array is located in the Jemez mountains near Los Alamos, New Mexico Altitude: 2,630m (8690ft) above sea level Altitude: 2,630m (8690ft) above sea level < Milagro <Umdgrb.umd.edu>

What is Milagro? Milagro is a large pool of water filled with Photo Multiplier Tubes Milagro is a large pool of water filled with Photo Multiplier Tubes The pond is 80m x 60m x 8m The pond is 80m x 60m x 8m The pond is lined on the bottom, covered on the top, and filled with water The pond is lined on the bottom, covered on the top, and filled with water Inside Milagro PMTs are suspended 1.5 and 6.5 meters below the water surface PMTs are suspended 1.5 and 6.5 meters below the water surface The full detector, completed in fall of 1998, includes 723 PMTs The full detector, completed in fall of 1998, includes 723 PMTs

< More Inside Milagro

Comparison of ACT : EASA An Air Cherenkov Telescope (ACT) is a system of mirrors that focuses Cherenkov light into PMTs to learn more about cosmic ray showers An Air Cherenkov Telescope (ACT) is a system of mirrors that focuses Cherenkov light into PMTs to learn more about cosmic ray showers They can only be operated at night They can only be operated at night An Extensive Air Shower Array (EASA) is characterized by sparsely positioned detectors (typically plastic scintillators) which emit light when a cosmic ray passes through them They can operate under all conditions, night or day Each type of cosmic ray detection has its own advantages and disadvantages Left: ACT Right: EASA <

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

Milagro’s Purpose and Goals Search for gamma-ray bursts emitting TeV gamma rays Search for gamma-ray bursts emitting TeV gamma rays Search for nearby active galactic nuclei (AGN) Search for nearby active galactic nuclei (AGN) Search the Northern Hemisphere sky for sources of TeV gamma rays Search the Northern Hemisphere sky for sources of TeV gamma rays Search for primordial black holes (PBH) Search for primordial black holes (PBH) Study the properties of the solar magnetic field Study the properties of the solar magnetic field < Simulated Shower Hitting Milagro

So what makes Milagro new? This is a new type of detector: a water Cherenkov extensive air shower array This is a new type of detector: a water Cherenkov extensive air shower array This is the first example of a large continuous pool being used as a gamma-ray telescope This is the first example of a large continuous pool being used as a gamma-ray telescope Using Milagro, we can observe the Universe over 20 order of magnitude in photon energy Using Milagro, we can observe the Universe over 20 order of magnitude in photon energy Milagro is the first telescope capable of continuously monitoring the Northern sky in this energy range. Milagro is the first telescope capable of continuously monitoring the Northern sky in this energy range.

Milagro Benefits The index refraction of water is much bigger than that of air The index refraction of water is much bigger than that of air The number of Cherenkov photons per unit track is greater The number of Cherenkov photons per unit track is greater The Cherenkov light angle in water is 41°, while it is only 1° in air The Cherenkov light angle in water is 41°, while it is only 1° in air More Material into which the particles can bump More Material into which the particles can bump <

In-Depth: Active Galactic Nuclei Active Galactic Nuclei are believed to be supermassive black holes surrounded by accretion disks Active Galactic Nuclei are believed to be supermassive black holes surrounded by accretion disks These “black holes” seem to emit beams of high energy particles These “black holes” seem to emit beams of high energy particles These beams, or jets, are spewed perpendicular to the disk These beams, or jets, are spewed perpendicular to the disk <

Another look at AGN

The Gadgets Pond, Liner, and Cover Pond, Liner, and Cover PMTs and anchor grid PMTs and anchor grid Cover inflation system Cover inflation system Lightning protection system Lightning protection system Water Purification and Circulation Apparatus Water Purification and Circulation Apparatus Data Acquisition and computer…stuff Data Acquisition and computer…stuff Environmental monitoring system Environmental monitoring system Computer Simulation Software Computer Simulation Software PMTs <

Nowadays at Milagro Publications in 2001 suggest activity still today Publications in 2001 suggest activity still today There is a collection of animations that show the research Milagro has accomplished in a few short years: There is a collection of animations that show the research Milagro has accomplished in a few short years: /E200MeV.html /E200MeV.html G2TeVBottom.html G2TeVBottom.html ges/EASIndexG2TeVPart.html ges/EASIndexG2TeVPart.html

George Mason University George Mason University Los Alamos National Laboratory Los Alamos National Laboratory New York University New York University University of California, Irvine University of California, Irvine University of California, Riverside University of California, Riverside University of California, Santa Cruz University of California, Santa Cruz University of Maryland, College Park University of Maryland, College Park University of New Hampshire, Durham University of New Hampshire, Durham University of Wisconsin University of Wisconsin < (Kinda Boring, But Important)

What did I tell You? Where the name comes from/location Where the name comes from/location What Milagro is and what it does What Milagro is and what it does Comparison of ACTs and EASAs Comparison of ACTs and EASAs Milagro’s purpose and goals Milagro’s purpose and goals Why is Milagro new/what are benefits? Why is Milagro new/what are benefits? In-Depth: Active Galactic Nuclei In-Depth: Active Galactic Nuclei Gadgets they use Gadgets they use Nowadays at Milagro (Animations) Nowadays at Milagro (Animations) Collaborators Collaborators I told you what I told you I told you what I told you

Bibliography tionIntro.html tionIntro.html (Who I stole my information and cool pictures from)