# Presentation: 823715

## Flavor Oscillations in LSND

- Neutrinos and oscillations
- The Liquid Scintillator Neutrino Detector
- Results
- The larger picture...
- The next step... BooNE

## Why Neutrinos?

- Dark matter in the universe, galactic dynamics
- Supernova explosions, how do they happen?
- Solar physics, our only view into the core of the sun
- Particle physics, why are they so light?

## Neutrino History

- 1914: Chadwick finds  decay spectrum to be continuous
- 1930:	W. Pauli proposed ‘neutron’ as an explanation
- 1936:	Fermi-Gamow-Teller theory with a “neutrino”
- 1956:	Cowan and Reines observe e interactions
- 1958: V-A theory of weak processes
- 1962:	Danby et al, observe  interactions
- 1990: Precisely 3 light neutrinos exist in nature
- 2000:	DONUT collaboration observes   interactions

## Standard Model

## Neutrino interactions are weak

- very small!

## Neutrino Mysteries

- Dark matter in the universe, galactic dynamics
- Supernova explosions, do they produce the element abundance seen in the universe?
- Solar physics, our only view into the core of the sun
- To answer the above we need to know more about neutrinos: do they have mass? Do they mix? Are there only three states?

## Neutrino Flavor Oscillations

- The neutrinos of weak interactions may be a quantum mechanical mixture of the the neutrinos that have unique masses. This leads to the phenomenon of neutrino flavor oscillations. For example:

## Neutrino’s at LAMPF/LANSCE

- E-31: 	1975-1980
- E-225:	1975-1993
- E-645:	1980-1993
- E-764:	1982-1992
- E-1173: 1989-1998

## The LSND Collaboration

- University of California, Riverside
- (Eric Church)
- University of California, San Diego
- University of California, Santa Barbara
- Embry Riddle Aeronautical University
- Linfield College
- Los Alamos National Laboratory
- (Bob Burman, Gerry Garvey, Bill Louis, Geoff Mills,
- Vern Sandberg, Ben Sapp, Rex Tayloe, Hywel White,...)
- Louisiana State University
- Southern University

## The LSND Experiment

- 800 MeV protons
- 1 mA
- 6% duty ratio

- L = 30 meters

- CH2

- ee )

- _Neutrino Targets in  CH__2__ :_
- 	  e  :   neutrons in 12C  +  electrons
- e  :   protons  in 12C  +  electrons  +  free protons

- 167 tons CH2
- 1220 PMT’s
- Active Veto Shield

- Cu Beam Dump

- Target

## Neutrino Fluxes

## LSND Neutrino Physics

-   interactions on 12C, e, p: 20-300 MeV

-  Oscillation Search:

## Event Time Structure

## Global Fit Parameters

## Fit Results (94-98)

## Oscillation Analysis Strategy

- Search for  e decay at rest oscillation events in the energy range 20-60 MeV
- Search for   e decay in flight oscillation events in the energy range 20-200 MeV
- Use common a primary-event electron selection across all neutrino processes
- Simultaneously fit all neutrino processes to constrain fluxes and backgrounds
- Identify 20-60 MeV electron events with correlated neutron capture    (e p e+n ) with correlated neutron capture gamma (R> 10)
- Fit 20-200 MeV oscillation signal in (E,R,L,cos) to determine best oscillation parameter values

## Analysis Improvements

- Global fit to all neutrino processes in order to constrain backgrounds
- Improved position resolution that gives better accidental gamma rejection in decay-at-rest analysis
- Correlated gamma efficiency improves from 23% to 40%
- Accidental background efficiency drops from 0.6% to 0.23%
- Combined decay-at-rest + decay-in-flight treatment when determining oscillation parameters

## Neutrino Oscillations 20-60 MeV

- _R>10 Selection:_
- _on__	__off__	__	____ bkgd__	__	__excess_
- 83	(-)33.7		(-)16.6		32.7±9.2
- _Fit to R distribution:_
- _Oscillation Excess__	__ Oscillation Probability_
- 83.3 ± 21.2		(0.25±0.06 ± 0.04)%

## Global Oscillation Fit

- Electron selection in energy range of 20-200 MeV
- Fit all backgrounds in (Ee, R, L, cos) and calculate likelihood at each (m2,sin2)

## Slide 26

## Summary

- LSND observes excess e p e+n  events which are not consistent with conventional neutrino processes
- A natural explanation is neutrino appearance due to *flavor oscillations* that have an overall probability of (0.25±0.06±0.04)% with a m2 > 0.2  eV2
- This is the only appearance evidence of neutrino oscillations at the present time

## The Larger Picture

- There are three signs of neutrino oscillations:

*With three flavors there are *
*only two independent ****m**2** !*

## Possible solutions

- One of the effects is not due to neutrino oscillations
- There is another (sterile) neutrino lurking in the universe
- Oscillations are due to the effects of extra dimensions (string theory)

*It is crucial to verify whether these *
*measurements are due to oscillations. *

## The next experiments:

- Solar Neutrinos:
*Sudbury Neutrino Observatory (SNO)*
- Goals: measure overall neutrino flux with neutral current interactions
- LSND effect
*Booster Neutrino Experiment (BooNE)*
- Verify LSND appearance effect
- Measure L/E dependence

## BooNE Experiment 

- BooNE Experiment

- Confirm and Measure  LSND Neutrino Oscillation Effect

## MiniBooNE Project

- _Purpose:_ Verify observations at Los Alamos of neutrino oscillations (LSND)
- _Supporting Organizations:_ DOE/ER/HEP, DOE/ER/NP, Los Alamos
- _Location:_ Fermi National Laboratory
- _Cost:_ ~ 18 M$

## Fermilab Site of BooNE

- BooNE Detector

- BooNE  Source

- 500 meters

## MiniBooNE Collaboration

- S. Koutsoliotas
- Bucknell University, Lewisburg, PA 17837
- E. Church, I. Stancu, G. J. VanDalen
- University of California, Riverside, CA 92521
- R. A. Johnson, N. Suwonjandee
- University of Cincinnati, Cincinnati, OH 45221
- L. Bugel, J. M. Conrad, J. Formaggio, M. H. Shaevitz,  Co-spokespersons: J.M. Conrad and W. C. Louis.
- B. Fleming, E. D. Zimmerman
- Columbia University, Nevis Labs, Irvington, NY 10533
- D. Smith
- Embry Riddle Aeronautical University, Prescott, AZ 86301
- C. Bhat, S. Brice, B.C.Brown, R. Ford, P. Kasper, I. Kourbanis,
-  A. Malensek, W. Marsh, P. Martin, F. Mills, C. Moore,
-  A.D. Russell, P. Spentzouris, R.J. Stefanski, T. Williams
-  Fermi National Accelerator Laboratory, Batavia, IL 60510
-  J. Boissevain, G. T. Garvey, E. Hawker, W. C. Louis*, G. B. Mills,
-  V. Sandberg, B. Sapp, R. Tayloe, D. H. White
-  Los Alamos National Laboratory, Los Alamos, NM 87545
- R. Imlay, H. J. Kim, A. Malik, W. Metcalf, M. Sung
- Louisiana State University, Baton Rouge, LA 70803
- B. Roe,  N. Wadia
- University of Michigan, Ann Arbor, MI 48109
- A. Bazarko, P. D. Meyers, F. C. Shoemaker
- Princeton University, Princeton, NJ 08544

## MiniBooNE Neutrino Source

## Proton Target Assembly

- 65-80 cm
- Gas Cooled
- Beryllium
- Target

- Primary 8 GeV proton beam:
-  5x1012 protons @ 5 Hz
-  600 W power load

## Horn Focused Pion Beam

- Target is inside the inner conductor
- of horn

- Charged pions and kaons are
- focused toward the detector
-                     with a single horn.

-  The Design:
- 170 kA, 5 Hz (average), 200M pulses/year

- 8 GeV protons

## MiniBooNE Detector Tank

-  Pure mineral oil throughout
- 807 tons total, 445 tons mineral oil
- 1280 phototubes in the detector region
- 240 phototubes in the veto region.

## MiniBooNE Schedule

- Civil construction started mid-1999 and will finish October 2000
- Beam line construction started mid 2000 and is scheduled to finish summer 2001
- Operation scheduled to start December 2001
- If LSND signal is observed, second detector construction is scheduled for ~2003