# Presentation: 143339

## Don Lincoln
Fermilab
f

- Don Lincoln
- Fermilab
- f

*Neutrinos:** *Ghosts of the Universe

## Beauty in the Universe

## Much is explained by quarks and electrons.But there remains the neutrino.....~109 /proton!!

##  decay

-  decay

- Observed

##  decay

-  decay

-          Dear radioactive ladies and gentlemen,
- ...I have hit upon a ‘desperate remedy’ to save...the law of conservation of energy. Namely the possibility that there exists in the nuclei electrically neutral particles, that I call neutrons...I agree that my remedy could seem incredible...but only the one who dare can win...
- Unfortunately I cannot appear in person, since I                                  am indispensable at a ball here in Zurich.
- Your humble servant
- W. Pauli

- December 4, 1930

- Note: this was before the
- discovery of the real neutron

## Project Poltergeist 1956

- Reines

- Cowan

- Signal 2, then several  ~few s later

- Experiment attempted at Hanford in 1953,
- too much background.  Repeated at Savannah
- River in 1955. [Flux: 1013 neutrinos/(cm2 s)]

## Neutrino Facts

- Neutrino from Enrico Fermi
- for “Little neutral one”

-  flux on Earth from Sun
- 6.5×1014/(m2 s)
- <E> ~ 0.3 MeV

- Neutrino from sun will pass through 5 LY of solid lead, with 50% chance of interacting

- Average number of solar neutrinos interacting in a person per year
-  30!
-  1 with ‘real energy’

## Neutrinos in Art

- Seattle Rock
- Band

- Neo-Swing

**Cosmic Gall **
**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. **
**John Updike *****Telephone Poles and Other Poems, *****1963 **

## More than one kind of neutrino?

- Mel
- Schwartz

- 		**Date:** 1962
- 		**Intent:** Measure weak force at high energies
**Expectation: **Since neutrinos
- 	are created with muons and
- 	electrons, the neutrino beam
- 	should create both electrons
- 	and muons in the detector.
**Result: **No electrons produced,
- 	only muons
**Conclusion:** There must be two
- 	kinds of neutrinos.

## What Good are Neutrinos?

- Neutrinos only feel the
- weak force.

- Over simplified

- Other probes of nucleon structure have to
- beat their way through the mess that is a
- real proton.
- Multiple interactions means messy interpretation.
- Neutrinos interact at most once, so the collision is more easily understood.

## Nucleon Structure

- 18 m

- 28 m

## Nucleon Structure

- Structure of the proton can be determined by scattering neutrinos (or other probe particles) into hydrogen target

## Typical Experiment

- Need lots of mass to force a neutrino to interact.
- Beam-based experiments typically have weight of ~1000 tons

## Neutrinos show number of generations

**Obvious Conclusion:** There are 3 generations
**Cautious Conclusion:** There are only three
-                                       flavors of low-mass
-                                       neutrinos into which
- 			  a Z can decay.

## Star Trek

- In the 1993 episode of *Star Trek: Deep Space* *9* called “Rivals” neutrinos were a plot twist.

- Quark was losing money.
- Jadzia noticed that 98% of neutrinos were spinning one way.
- She explains half should spin each way.
- The crew locates ‘luck changing’ machines.

- Hah!

- Neutrino Sources

- Solar neutrinos
- p + p  d + e+ + e
- 8B  8Be + e+ + e
- Sun emits e
-     2×1038 s-1

- A 5-10 GW reactor
- complex has a neutrino
- flux of ~1020 s-1

- Neutrinos from
- cosmic rays
- ~100 m-2 s-1

- Uranium and Thorium in the Earth’s crust decay about 15 TW of energy.
- Neutrino flux on Earth’s surface
- (from Earth)
- ~ 5×1010 s-1 m-2

## Homestake Gold Mine

- 100,000 gallons of cleaning fluid C2Cl4
- Expected 1.5 interactions per day
- Measured 0.5 interactions per day
- Sensitive to 8B solar neutrinos only
- e + 37Cl  e- + 37Ar

- Ray
- Davis

- John
- Bahcall

- 1968!

## SAGE 

- Measured: 77 6  3 SNU
- Predicted: 123 + 9 -7 SNU

- Soviet-American Gallium Experiment

- SAGE

- 71Ga +    71Ge + e-
- Sensitive to pp fusion in sun.
- 50 metric tons of Gallium
- They extract a *few tens of atoms*
- of Germanium

## Solar NeutrinoSummary

- Solar NeutrinoSummary

- Different experiments are sensitive to different solar processes.

- But all experiments show a marked deficit of electron neutrinos.
- Could reflect ignorance of how the sun works.
- Except.....

## Accidental Evidence

- In the early 1980s, two experiments (IMB Irvine-Michigan-Brookhaven) and (Kamiokande) were built to look for proton decay.
- None detected.  Proton lifetime > 1033 years.

- Simulated Event

- 7:36 	neutrinos observed
- 9:30 	amateur astronomer observes Tarantula Nebula in LMC.  Nothing unusual.
- 10:30 LMC photographed, SN1987A observed.
- ~3 hours for shock wave to hit surface.

- SN 1987A

## Background Becomes Signal

-                       Expected average ratio *R* = 1.

- If proton decay goes as

- Signal is ring in detector. Anything
- that can make a ring is background.

- In cosmic ray
- showers,
- expect 2 
- for each e

- Knowledge of detector response problematic.  Compensate by double ratio:

## Hmmmm.....

## Hmmmm.....

## Quantum Cobwebs

- Remember that information on a state is encoded in a wave function.
- Remember that you can express the wave function in any orthogonal basis (coordinate system).

- Under the electromagnetic force, the electrically-charged object (say an electron) is an eigenstate of mass and electrical charge.

- Under the weak force, the weak-charged object (say an neutrino) is not both an eigenstate of mass and weak charge.

- Weak charge = k1 (mass 1) + k2 (mass 2)
-                          k21 + k22 = 1

## Massive Neutrinos Math

## Massive Neutrinos Math

- Important!

## Massive Neutrinos Math

- Substitute weak
- basis

- Time dependent
- Schrodinger equation

## Massive Neutrinos Math

- Reasonable approximations

- Initial conditions

- Evaluate

## Massive Neutrinos Math

## Super Kamiokande

## Super Kamiokande

- 11 stories high
- 1,000 meters underground
- 50,000 tons of water
- 22,500 tons fiducial volume
- 11,200 photomultipliers
- 0.5 meter photomultiplier diameter
- Abandoned zinc mine

## Super Kamiokande Discovery

- Announcement June 5, 1998

- Gist:  “There are fewer upcoming muon neutrinos than expected from down-going neutrino flux.  Data consistent with neutrino oscillations.”

## SNO

- Cerenkov detector
- Heavy water (can do solar model independent measurements)
- 6800 feet underground
- 9600 PMTs

- Sudbury
-    Neutrino
-        Observatory

- In Sudbury, Ontario

## SNO Physicsand Results

- SNO Physicsand Results

- Charged interactions convert neutron to proton.  Sensitive only to e.
- 30 events/day

- Neutral interactions disassociate deuteron into  neutron and proton.  Sensitive to e, , .
- 30 events/day

- Electron scattering mostly sensitive to e, with small contribution from  ,  .
- 3 events/day

- Comparison of SNO results with Super K indicates that the neutrino flux from the sun contains muon neutrinos, supporting neutrino oscillations.

- Announcement:
- June 18, 2001

## So What Does It Mean?

- Data is consistent with neutrino oscillations.  This can be accommodated, but not explained, by known physics.
- Data from solar and atmospheric neutrinos is consistent with               m1 ~ m2  m3
- Solar electron neutrinos disappear and reappear into muon neutrinos
- Atmospheric muon neutrinos disappear and reappear into tau neutrinos

## Cosmological Implications of Neutrinos

-  ~ 330 /cm3 (from Big Bang)
- <E> ~ 0.0004 eV (from Big Bang)
- Runiverse ~ 1010 lightyears
- Vuniverse ~ 4×1084 cm3
- N ~ 1087
- E(total) ~ 4×1083 eV
- M(equivalent) ~ 7×1047 kg
- Muniverse(visible) ~ 4×1052 kg

- If neutrinos were
- massive objects, they
- could contribute
- significantly to the mass
- of the universe.

- Are Neutrinos Massless?

- 0.1% < M < 18%

## Disaster Strikes!

- At 11:00, November 12, 2001,
- about 60% of the phototubes
- used in the Super-K detector
- imploded within a few seconds.
-           $21,000,000 damage

- We will rebuild the detector. There is no question.    		- Yoji Totsuka
-                       Director, Super-K Observatory

- Osama bin Laden on Super-K Disaster:
- Neutrinos are “...an abomination on the face of god...” and the search for neutrino mixing is: “...idolatry, which will be smashed beneath the fist of righteousness...”

## Outstanding Questions

- do not confirm.
- Highly controversial result.  If true, significant
-                        theoretical work needs doing.

- Fermilab’s MiniBoone
- to confirm or refute
- Summer 2002

- Liquid Scintillator
- Neutrino Detector

- LSND

- 1996

## Neutrino Summary

- They interact with ordinary matter               very weakly.
- Many experiments not mentioned           here are ongoing to unravel this                  rich behavior.

- Their behavior is highly complex and will need new physics to explain it.

## www-d0.fnal.gov/~lucifer/PowerPoint/Neutrinos.ppt