1. Exploring the Universe with Particles and Rays: α, β, γ, X, Cosmic, … Toby Burnett Prof, UW

2. WALTA meeting Feb 9, 20022 So what is a ray ? ray : A thin line or narrow beam of light or other radiant energy. ra·di·a·tion : 1. Emission and propagation and emission of energy in the form of rays or waves. 2. Energy radiated or transmitted as rays, waves, in the form of particles. 3. A stream of particles or electromagnetic waves emitted by the atoms and molecules of a radioactive substance as a result of nuclear decay. Common theme: l A source emits a particle, which l propagates in space, until it l interacts with another particle,. l producing secondary particles that are detected

3. WALTA meeting Feb 9, 20023 Dictionary prop·a·ga·tion l The act or process of propagating, especially the process by which a disturbance, such as the motion of electromagnetic or sound waves, is transmitted through a medium such as air or water.

4. WALTA meeting Feb 9, 20024 Waves or particles? Particle: point-like object Wave: spread-out Quantum mechanics in a nutshell: l Light, and all radiation, is discrete. (quantized) l The quanta of light are particles called photons, that have zero mass. (Same for all EM waves.) l Emission and absorption: behave like particles. l Propagation is wave-like. (Famous example: double-slit) l Energy and frequency are the same thing! (E=hf) l Same for momentum and inverse wavelength (p=mv=h/ ) Special relativity: l No particle can travel faster than the speed of light c = 3x10 8 m/s = 30 cm/ns. l E 2 = m 2 c 4 + p 2 c 2

5. WALTA meeting Feb 9, 20025 Experiments and observations Recall the theme: source  propagation  interaction  secondaries  detector Each stage can provide info about the world around us. Consider a microscope. detection system (light) source interaction photon detector Wavelength: limits resolving power. Solution: use higher energy (like electrons) Same paradigm as particle accelerators, one reason for high energy

6. WALTA meeting Feb 9, 20026 …and a telescope This is a photon detector designed to collect as many as possible from a distant source, and measure the precise direction photons astrophysical, or cosmological process Interesting things can happen here!

7. WALTA meeting Feb 9, 20027 The electron Volt SI unit of energy: joule. We use the electron Volt (eV) energy gained by an electron passing through a electrical potential difference  V of 1 Volt. (Energy is force x distance) 1 eV = 1.6 x 10 -19 J. This is the scale of chemical interactions. Photons detected from space: 3 degree microwave background 3 x 10 -4 eV Visible light3 eV Highest energy ever seen 10 12 eV = 1 TeV Prefixes MeV10 6 GeV10 9 TeV10 12

8. WALTA meeting Feb 9, 20028 A rather big microscope The Fermilab Tevatron particle accelerator. l accelerates protons to 1 TeV l uses some to make anti- protons (in collisions) l accelerates anti-protons to 1 TeV. l collides them! Why? l Study nature of matter by analyzing produced particles Current run information http://www-bd.fnal.gov/servlets/d11

9. WALTA meeting Feb 9, 20029 The D0 experiment: running now Online pictures Online pictures http://d0.phys.washington.edu/Projects/live_event/ a real pictureschematic view

10. WALTA meeting Feb 9, 200210 GLAST: A telescope for gamma rays! Low Earth orbit: 500 km, 27 o Launch March 2006 from Cape Canaveral, Delta II Energies 20 MeV - ~500 GeV Compared with an optical telescope: l No focussing! l Huge field of view l Poor (energy- dependant) angular resolution l Integral spectroscopy (~10%) GLAST has 2 instruments l Large Area Telescope(LAT) l GLAST Burst Monitor (GBM)

11. WALTA meeting Feb 9, 200211 The “Standard Model” A unifying framework, description of particles and forces. Known to not be complete: challenge to find the missing pieces that will show up at higher energies. A fancy poster http://particleadventure.org/particleadventure/frameless/chart_cutouts/particle_chart.pdf