16 May 2005 Debbie Harris, PARTICLE DAY 1

From Illinois to Minnesota in 1/400 of a second

Debbie HarrisFermilab

PARTICLE DAY

16 May 2005 Debbie Harris, PARTICLE DAY 2

What is this all about?

• What’s a neutrino?• Where do they come from?• How do you make them?• Why would you send them from

Fermilab (in Illinois) to Minnesota?

16 May 2005 Debbie Harris, PARTICLE DAY 3

Neutrinos are Everywhere…

• Neutrinos are tiny particles with no charge that weigh less than any other particle we know about (except for light)

• There are more neutrinos than any other particle in the universe—by more than a billion! (except for light)

16 May 2005 Debbie Harris, PARTICLE DAY 4

How did they get here?

• Neutrinos are made all the time:• In the Beginning• As the sun shines• As the supernova

explodes• As the banana splits• Every time atoms fall apart or

come together

16 May 2005 Debbie Harris, PARTICLE DAY 5

So why haven’t I heard of them before?

• One neutrino can go through a distance of 200 earths before interacting!

• Someone only figured out they might exist in ~1930 (Pauli)

• Seen for the first time in 1956 by putting a detector near a nuclear reactor (Reines and Cowan)

ν …

16 May 2005 Debbie Harris, PARTICLE DAY 6

How can humans make neutrinos?• Nuclear Reactors

• Huge amount of energy leaves reactor as neutrinos!• Make a beam of particles that decay to neutrinos

• Start with particles you already have: protons• Give the protons energy with an accelerator • Slam high energy protons against a target to make

new unstable particles• Focus!• Give the particles free space to fly through so they

can decay instead of interact

16 May 2005 Debbie Harris, PARTICLE DAY 7

So what’s the catch?

• Since neutrinos interact so rarely (1 in a billion…)• Have to make a lot of them

(billions)

• Have to give them a lot of chances to interact (huge detectors)

16 May 2005 Debbie Harris, PARTICLE DAY 8

How can you shoot a beam to Minnesota?• Imagine you have a laser, and you

want to shoot from here to Boston• What direction would you point your

flashlight? (hint: the earth is round)

• The neutrino beam has to go at that same angle (3.5o down from horizon)

735 km

16 May 2005 Debbie Harris, PARTICLE DAY 9

Digging a hole towards Minnesota• Using the latest in subway line

excavation, we built a huge tunnel 2/3 mile long, 21’ diameter

16 May 2005 Debbie Harris, PARTICLE DAY 10

Filling the hole towards Minnesota• Have to lower magnets weighing many tons down

the shafts• Have to put a big pipe

down the shaft

• Have to pour concrete all around the decay pipe to use as shielding for all the stuff that gets made that hits the walls

• Have to put a near detector in the last section of the hole

16 May 2005 Debbie Harris, PARTICLE DAY 11

Getting the Protons to the target

16 May 2005 Debbie Harris, PARTICLE DAY 12

Target and shielding

• .9m of graphite, has to absorb the power of 200 hair dryers on a spot 2mm in diameter!

Hint: to do this,Need lots of

cooling…

16 May 2005 Debbie Harris, PARTICLE DAY 13

Focusing what comes off the target• Has to be able to take

200,000 Amps!

Better cool this too!

16 May 2005 Debbie Harris, PARTICLE DAY 14

What else gets made?

• When these unstable particles decay, they make neutrinos and muons

• There are also some protons left over that went straight through the target

• Want separate detectors to measure both!

absorber

16 May 2005 Debbie Harris, PARTICLE DAY 15

How can you see a neutrino?

• These three neutrinos (ν’s) are associated with three charged particles, who are as different in size as • Squirrel (e: electron)• Lion (μ: muon)• Elephant (τ: tau)

ν

p

e,μ,or τ

n

You can’t see the neutrino, but you can see their partners

16 May 2005 Debbie Harris, PARTICLE DAY 16

Neutrino Detectors

• Because neutrinos interact so rarely, need LOTS of detector…

Far detector:

•5400 tons of Steel and scintillator•2½ stories tall!•½ mile underground in Soudan Mine, MN

Near detector: 5x Smaller, 1000 times closer

16 May 2005 Debbie Harris, PARTICLE DAY 17

Why are you sending neutrinos from Illinois to Minnesota?

• There are three kinds of neutrinos, and there is evidence that they can change from one kind to another

• For these neutrinos, need towait ~1/400 of a second: if you’re traveling the speed of light, this means about 450 miles

e μ τ

16 May 2005 Debbie Harris, PARTICLE DAY 18

Why study changing neutrinos?• Neutrinos changing

from one flavor to another might tell us about • why there is so

much more matter than antimatter in the universe…

• Why we have so many particles that have such very different weights

16 May 2005 Debbie Harris, PARTICLE DAY 19

Anatomy of an experiment• Design• Construction • Commission –does everything

work the way you planned? • Take the data • Analyze the data• Publish your results

Sounds familiar, doesn’t it?

16 May 2005 Debbie Harris, PARTICLE DAY 20

How long does this take?

• Design can take several years• Getting funding takes time…• Construction:

• Detectors were 1-2 year long projects• Beamline took 4 years! (including all the

underground construction)• Commission: 6 months?• Run: 3 to 5 years• Analyze data: depends, but can be a few

more years…• Moral: need to be patient, or work on more

than one experiment at once…

16 May 2005 Debbie Harris, PARTICLE DAY 21

Who is on this experiment?

• ~250 physicists and engineers from 6 countries

16 May 2005 Debbie Harris, PARTICLE DAY 22

So what do I have to do with all this?

• I have been on this experiment for 5 years• Proton Detectors

• Before the target: how many do we need?• After the target: can one be built to survive?

• Muon Detectors• What can they tell us about the neutrinos?• How big, how many do we need?

We’re just now starting to take data, so now I get to see how well everything works…

16 May 2005 Debbie Harris, PARTICLE DAY 23

First Protons to the beamline: December 3In 10 carefully planned shots,Got the proton beam all the way From the Main Injector to the End of the decay pipe

Hit the monitor dead center to within an inch, a mile from where the protons started!

16 May 2005 Debbie Harris, PARTICLE DAY 24

First Neutrinos seen in Near Detector January 21

• Put target in the way of the protons, make the particles that decay to neutrinos

• See muons(madewith neutrinos) right away

• See neutrinos by4th time we sent protons to the target

16 May 2005 Debbie Harris, PARTICLE DAY 25

First neutrinos seen in Far Detector: March 20• Learn how to send 10 TRILLION

protons to the target every 3 seconds

• Learn how to cool everything the protons hit fast enough

• Roughly every 1019 protons, should get a neutrino in Minnesota

16 May 2005 Debbie Harris, PARTICLE DAY 26

First Neutrino from Illinois• Arrived 2.5msec after sending

protons to target

This is a high energy lion-type neutrino!

16 May 2005 Debbie Harris, PARTICLE DAY 27

Do all lab experiments work perfectly?

• Leaky Target• the target has pipes

around it that carry water to cool it

• On March 23, discovered a leak

• What does it look like to the detector at the end of the beamline?

16 May 2005 Debbie Harris, PARTICLE DAY 28

Fixing the problem

• 6 weeks later, we came up with a solution (pushing on the hole from the other side) and we are starting to run again (see next far detector neutrino event)• What happens with a target that had

water in it?• How long will the leak stay plugged?• How quickly can we build all the spare

parts we need?

16 May 2005 Debbie Harris, PARTICLE DAY 29

More neutrinos arriving daily…

• This looks like a lion (with low energy)

16 May 2005 Debbie Harris, PARTICLE DAY 30

So what have I learned?

• Be prepared: you’ll never predict what will go wrong with your experiment but something will go wrong…

• Lots of things will work just like you predicted—but it will seem like magic anyway

• Stay tuned, we’ll learn soon if we see neutrinos changing!

16 May 2005 Debbie Harris, PARTICLE DAY 31

So what have you learned?

• Questions? Please ask!!!

• Or visit http://www-numi.fnal.gov