Post on 21-Dec-2015
A Visit to Ghost Ranch
Jim Linnemann
Michigan State University &
Los Alamos National Laboratory
June 18, 2003
The Milagro All-Sky TeV Gamma-Ray Telescope
Look for high energy photons “particles” of light
Photons point back see where they came from
Recent ResultsCrab nebulaAll-sky surveyGalactic PlaneGRB searches
Look for high energy photons “particles” of light
Photons point back see where they came from
Recent ResultsCrab nebulaAll-sky surveyGalactic PlaneGRB searches
What are Cosmic Rays?• Fast moving particles from—
the cosmos: of no earthly origin` But then, the same is true of
starlight
– Most are electrically charged
• How do you see them? (Experimental Physics)– Finding a way to detect things– “extrasensory” perception
• Real phenomena, right under our noses• The lure of secret knowledge still attracts…
Milagro Detector
Moon Shadow: Energy Scale Calibration
Proton ResponseE = 640±70 GeV (MC 690 GeV) = 0.9o
The moon’s shadow is sharp:
blurred only by earth’s magnetic
field and detector’s resolution
The Sun Produces some Cosmic Rays: A Solar Prominence
Material Ejected from the Sun by Magnetic Fields
The sun’s magnetic field deflects cosmic
rays and blurs its image
Can use to
study the sun
The Milky Way—seen in light 100 million times more energetic than light from the sun
A satellite
A Source of Gamma Rays: The Crab Nebula
Supernova seen in 1054 AD
Still shining: light particles with 1 trillion times more energy than sunlight photons
A spinning neutron star with a strong magnetic
field (pulsar)
Accelerates electrons, which transfer much of their energy to photons
The Crab Nebula Raw Data
On: 16,987,703
Off: 16,981,520
Significance: 1.4
Raw Data
On: 16,987,703
Off: 16,981,520
Significance: 1.4
Cut Data
On: 1,952,917
Off: 1,945,109
Excess: 7,808 (~10/day)
Significance: 5.4
Cut Data
On: 1,952,917
Off: 1,945,109
Excess: 7,808 (~10/day)
Significance: 5.4
An Active Galactic Nucleus
Gravity, Magnetic Fields, and Relativity combine to send energetic light particles across the universe…
Colliding neutron stars making black holes: one model for distant gamma ray bursts
Sources change with energy:
Leave traces in spectrum