In late 1990, Tim Berners-Lee, a scientist at CERN, the European Organisation for Nuclear Research, invented the World Wide Web. Originally conceived to meet the demand for automatic information sharing between scientists working in different universities and institutes all over the world, it has now millions of users everyday worldwide.

Fundamental Research studied without regard to practical applications Practical science Vs. Fundamental science In late 1990, Tim Berners-Lee, a scientist at CERN, the European Organisation for Nuclear Research, invented the World Wide Web. Originally conceived to meet the demand for automatic information sharing between scientists working in different universities and institutes all over the world, it has now millions of users everyday worldwide. Is Fundamental science impractical?

Particle Astrophysics

Particle Physics T There are many particles We are built out of only 3 Other particles, like neutrinos, are created in particle accelerators or in space. protons neutronselectrons

Cosmic Gall A Poem by John Updike ( ) NEUTRINOS, they are very small. They have no charge and have no mass * And do not interact at all. ** The earth is just a silly ball To them, through which they simply pass, Like dustmaids down a drafty hall Or photons through a sheet of glass. They snub the most exquisite gas, Ignore the most substantial wall, Cold shoulder steel and sounding brass, Insult the stallion in his stall, And scorning barriers of class, Infiltrate you and me! Like tall and painless guillotines, they fall Down through our heads into the grass. At night, they enter at Nepal and pierce the lover and his lass From underneath the bed-you call It wonderful; I call it crass. - Telephone Poles and Other Poems, John Updike, Knopf, 1960 * They actually do have a very very very small mass ** Neutrinos do interact – but it is a super rare interaction

Neutrinos are very Rare particles False: We know that neutrinos are created in the sun and in the atmosphere. Every second thousands of neutrinos go through our body. In IceCube we look for energetic neutrinos from outer space. These are rare.

Neutrinos Are very small Have (almost) no mass And rarely interact at all

If we want to see And interact with our detector This must arrive to our detector must emit.

Traditional astronomy uses photons (light particles) as messengers A Telescope (visible light, or X-ray or gamma-ray)

Sometimes 1” of matter is enough to stop a photon True: Cover your eyes

? I need a different messenger Traditional astronomy uses photons (light particles) as messengers Space is not empty. A Telescope (visible light, or X-ray or gamma-ray)

To stop a neutrino we need 10 miles of matter False: We will need much more matter to stop a neutrino

To make sure we stop every neutrino we would need 10 light years of lead. This is 1 million times the distance to the Sun full with heavy dense material

Traditional astronomy uses photons (light particles) as messengers In IceCube we use Neutrinos to do astronomy Neutrino detector

Hey, Wait a minute: If those “neutrinos” rarely interact, they will also “rarely” interact with our detector

A VERY BIG DETECTOR

How to detect a neutrino Sonic Boom (Shock caused by moving faster than the speed of sound) Cherenkov effect - “Optic” Boom (when a charged particle passes through matter at a speed greater than the speed of light in matter) If a neutrino interacts in our detector, it produces a super energetic charged particle that moves super fast What happens when things move fast??

Requirements from a neutrino detector rarely interact.  large detectors Light measurement  Dark  Transparent Cost  Cheap material Where to put it?

IceCube will be made of 80 strings deployed in holes 1.5 miles deep (!) The bottom 0.6 miles of each string is instrumented with 60 super sensitive detectors. “eyes” A cubic kilometer array of light detectors will look for this weak light 1.5 mile 0.6 mile

1.5 mile 0.6 mile IceCube will be made of 80 strings deployed in holes 1.5 miles deep (!) The bottom 0.6 miles of each string is instrumented with 60 super sensitive detectors. “eyes” A cubic kilometer array of light detectors will look for this weak light

The eye in the ice DOM Digital Optical Module

IceCube South Pole Dome New Station road to work Ski-Runway (road to home) IceCube – where are we?