# Presentation: 520257

## MiniBooNE and the SNS

**H. Ray**
*Los Alamos National Laboratory*

- Overview of MiniBooNE & Current Status
- Neutrino Physics in a Post-MiniBooNE Era

## Outline

- LSND : The motivation for MiniBooNE
- MiniBooNE Summary
- The SNS
- Properties of the neutrino beam
- Proposed detectors
- Interactions of neutrinos in the detectors
- How to use these interactions to test neutrino physics models

- H. Ray

## Neutrino Oscillations

**P****osc**** =****sin****2****2******** sin****2**** 1.27 ********m****2**** ****L**
**	****	****	****	****	****	****E**

**Distance from point of creation of neutrino beam to detection point **

****** ****Is the mixing angle**

******m****2  ****is the mass squared difference between the two neutrino states**

**E is the energy of the neutrino beam**

- H. Ray

**Notes:**
Tell people what the units are, say units are funky b/c of hbar, c, etc. (in 1.27)
L and E are expt things, m and theta are physics properties
Have to determine 2 physics things from 1 thing you measure = correlated 

## Observing  Interactions

- Don’t look directly for neutrinos
- Look for products of neutrino interactions
- Passage of charged particles through matter leaves a distinct mark
**Cerenkov effect / light**
**Scintillation light**

- H. Ray

## Cerenkov and Scintillation Light

- Charged particles deposit energy in the medium
- Isotropic, delayed

- Charged particles with a velocity greater than the speed of light * in the medium* produce an E-M shock wave
-  v > 1/n
- Similar to a sonic boom
-  Prompt light signature

- H. Ray

## The (In)famous LSND

- 800 MeV proton beam + H20 target, Copper beam stop
- 167 ton tank, liquid scintillator, 25% PMT coverage
- E ~20-50 MeV
- L ~25-35 meters
-  e + p  e+ + n
- n + p  d  +  (2.2 MeV)

- H. Ray

## The LSND Result

- Different from other oscillation signals
- Higher m2
-  Smaller mixing angle
- Much smaller probability (very small signal) ~0.3%

- H. Ray

## The LSND Problem

**P****osc**** =****sin****2****2******** sin****2****  1.27 ********m****2**** ****L**

**        ****E**

- m2ab= ma2 - mb2

- Something must be wrong!
- Flux calculation
- Measurement in the detector
- Both
- Neither

**Reminiscent of the great Ray Davis**
**Homestake missing solar neutrino problem!**

- H. Ray

## Confirming LSND

**P****osc**** =****sin****2****2******** sin****2****  1.27 ********m****2**** ****L**

**        ****E**

- m2ab= ma2 - mb2

- Want the same L/E
- Want higher statistics
- Want different sources of systematic errors
- Want different signal signature and backgrounds

- H. Ray

## MiniBooNE

- H. Ray

## MiniBooNE Neutrino Beam

- Start with an 8 GeV beam of protons from the booster

- Fermilab

- H. Ray

## MiniBooNE Neutrino Beam

- The proton beam enters the magnetic horn where it interacts with a Beryllium target
- Focusing horn allows us to run in neutrino, anti-neutrino mode
- Collected ~6x1020 POT, ~600,000  events
- Running in anti- mode now, collected ~1x1020 POT

- Fermilab

- H. Ray

**Notes:**
State of the art device, just set another world record for pulses!
Previous record set by us was 100M, before MB = 10M pulses

## MiniBooNE Neutrino Beam

- p + Be = stream of mesons (, K)
- Mesons decay into the neutrino beam seen by the detector
- K+ / +  + + 
- +  e+ +  +  e

- Fermilab

- H. Ray

## MiniBooNE Neutrino Beam

- An absorber is in place to stop muons and un-decayed mesons
-  Neutrino beam travels through 450 m of dirt absorber before arriving at the MiniBooNE detector

- Fermilab

- H. Ray

## MiniBooNE Detector

- 12.2 meter diameter sphere
**Pure**** **mineral oil
- 2 regions
**Inner light-tight region, 1280 PMTs (10% coverage)**
**Optically isolated outer veto-region, 240 PMTs**

- H. Ray

**Notes:**
1st expt to use non-doped oil!

## Event Signature

- H. Ray

## MiniBooNE Current Status

- MiniBooNE is performing a blind analysis (closed box)
- Some of the info in all of the data
- All of the info in some of the data
- All of the info in all of the data

- H. Ray

**Notes:**
Mention finalizing systematic errors

## MiniBooNE Current Status

- MiniBooNE is performing a blind analysis (closed box)
- Some of the info in all of the data
- All of the info in some of the data
- All of the info in all of the data

**We haven’t yet opened the box**

- H. Ray

**Notes:**
Mention finalizing systematic errors

## Final Outcomes

**Confirm LSND**

**Inconclusive**

**Reject LSND**

- H. Ray

## Final Outcomes

**Confirm LSND**

**Inconclusive**

**Reject LSND**

**Need to determine **
**what causes **
**oscillations**

- H. Ray

## Final Outcomes

**Confirm LSND**

**Inconclusive**

**Reject LSND**

**Need to collect **
**more data / perform **
**a new experiment**

- H. Ray

## Final Outcomes

**Confirm LSND**

**Inconclusive**

**Reject LSND**

**Need to determine **
**what causes **
**oscillations**

**Need to collect **
**more data / perform **
**a new experiment**

**SNS**

- H. Ray

## Final Outcomes

**Confirm LSND**

**Inconclusive**

**Reject LSND**

- H. Ray

## Final Outcomes

**Confirm LSND**

**Inconclusive**

**Reject LSND**

**SNS**

- H. Ray

## All Roads Lead to the SNS

**Confirm LSND**

**Inconclusive**

**Reject LSND**

**Need to determine **
**what causes **
**oscillations**

**Need to collect **
**more data / perform **
**a new experiment**

**SNS**

- H. Ray

## What is the SNS?

- Accelerator based neutron source in Oak Ridge, TN

- Spallation Neutron Source

- H. Ray

## The Spallation Neutron Source

- Pulsed bunches of 1 GeV protons sent into liquid mercury target 60 times/second
- Pulses 695 ns wide (LAMPF = 600 s wide, FNAL = 1600 ns wide)
- Neutrons freed by the spallation process are collected and guided through beam lines to various experiments
- Neutrinos come for free

- H. Ray

**Notes:**
Mercury : not damaged by radiation as are solids, source of numerous neutrons b/c of high atomic number, 
Liquid at room temp, able to dissipate large, rapid rise in Temp & withstand shock effects from pulses

## The Spallation Neutron Source

- Target Area

- - absorbed by target

- +DAR

- Mono-Energetic!
- = 29.8 MeV

- E range up to 52.8 MeV

*(Liquid Mercury (Hg+) target)*

- H. Ray

## The Spallation Neutron Source

-  +  + + 
-   = 26 ns
-  +  e+ +  + e
-   = 2.2 s

- Pulse timing, beam width, lifetime of particles = excellent separation of neutrino types

- H. Ray

**Notes:**
Simple on beam timing cut = 72% pure nu-mu sample

## The Spallation Neutron Source

-  +  + + 
-   = 26 ns
-  +  e+ +  + e
-   = 2.2 s

- Mono-energetic 
-  E = 29.8 MeV
-  , e = known distributions
-  end-point E = 52.8 MeV

**MiniBooNE**

**SNS**

**GeV**

- H. Ray

## SNS Near Detectors

- 2 near detectors
- Mini-MiniBooNE
- Segemented Detector
- 2004 : LOI submitted to Oak Ridge
- August 2005 : proposal submitted to DOE
- Status : awaiting funding

- H. Ray

## SNS Far Detector

- MiniBooNE/LSND-type detector
- Higher PMT coverage (25% vs 10%)
- Mineral oil + scintillator (vs pure oil)
- Faster electronics (200 MHz vs 10 MHz)
- ~60m upstream of the beam dump/target
- Removes DIF bgd

- H. Ray

## Neutrino Interactions

- Elastic Scattering
- Quasi-Elastic Scattering
- Single Pion Production
- Deep Inelastic Scattering

**MeV**
**GeV**

- H. Ray

## Neutrino Interactions

- Elastic Scattering
- Quasi-Elastic Scattering
- Single Pion Production
- Deep Inelastic Scattering

**MeV**
**GeV**

- SNS Allowed Interactions

- H. Ray

## Elastic Scattering

- Target left intact
- Neutrinos can elastic scatter from any particle (electrons, protons)
- Neutrino imparts recoil energy to target = how we observe these interactions

**Z**

******e**

**e****-**

**e****-**

******e**

- H. Ray

## Quasi-elastic Scattering

- Neutrino in, charged lepton out
- Target changes type
- Need to conserve electric charge at every vertex
- Need minimum neutrino E
- Need enough CM energy to make the two outgoing particles

**n**

**p**

**W****+**

******e**

**e-**

- H. Ray

## Neutrino Interactions @ SNS

- All neutrinos produced from a ***Decay At Rest***** **source
- All neutrino types may engage in NC interactions
- Muon mass = 105.7 MeV, Electron mass = 0.511 MeV
- Muon neutrinos do not have a high enough energy at the SNS to engage in CC interactions!

- H. Ray

##  and anti-  Osc. Searches

- 2 oscillation searches at SNS can be performed with CC interactions to look for flavor change
- Appearance :   e   (ala LSND)
- e + p  e+ + n
- n + p  d + 2.2 MeV photon
- Appearance :   e
- e + 12C   e- + 12Ngs
- 12Ngs   12C + e+ (~8 MeV) + e
- MiniBooNE uses e + n   e- + p

- lower E e vs        higher E  e

- H. Ray

## Neutrino Interactions @ SNS

- Appearance :   e
- e + 12C   e- + 12N
- 12N   12C + e+ (~8 MeV) + e

- Intrinsic e vs        mono-energetic e  from 

- E of e- (MeV)

- E of e- (MeV)

- H. Ray

## _x0008_How do we use these interactions to search for new physics?

## Sterile Neutrinos

- Sterile neutrinos = RH neutrinos, don’t interact with other matter (LH = Weak)
- Use super-allowed NC interactions to search for oscillations between flavor states and sterile neutrinos
- Disappearance :   e
- + C   + C *
- C *  C + 15.11 MeV photon
- One detector : look for deficit in  events
- Two detectors : compare overall x event rates

- H. Ray

**Notes:**
R-process = heavy element production in supernova through rapid-neutron-capture.
Observed abundance of heavy elements >> SM prediction b/c available neutron density too small
Can be explained if oscillatoins to sterile neutrinos

## Sterile Neutrinos

- Near Detector only

- Near + Far Detector

- H. Ray

## Mass Varying Neutrinos

- All positive oscillation signals occur in matter (K2K, KamLAND, LSND); no direct information on oscillation parameters in air/vacuum
- Impose relationship between nus + dark E through scalar field
- Scalar field couples to matter field = different osc parameters in vacuum & mediums
- MaVaNus + 1 Sterile nu = LSND yes, MB no!
- Require a path to detector which can be vacated/filled with dirt to test
- Barger, Marfalia, Whisnant.  Phys. Rev. D 73, 013005 (2006)
- Schwetz, Winter.  Phys. Lett. B633, 557-562 (2006)

- H. Ray

## Lorentz Violation

- LSND, Atm, Solar oscillations explained by small Lorentz violation
- Size of violation consistent with size of effects emerging from underlying unified theory at Planck scale
- Kostelecky, Mewes.  hep-ph/0406255  (2004)
- Oscillations depend on direction of  propagation
- Don’t need to introduce neutrino mass!
- Look for sidereal variations in oscillation probability

- H. Ray

## CP/CPT Violation

- CPT violation (or CP + sterile neutrinos) allows different mixing for , anti-
- Possible explaination for positive LSND, null MiniBooNE
- Compare , anti- measured oscillation probabilities
-  CP :   e      e
-  CPT :   e   e      can’t do at SNS!
-  CPT :   X    X

- H. Ray

## Why the SNS?

**Confirm LSND**

**Inconclusive**

**Reject LSND**

**Looking for**
**new physics**

**Need much higher **
**statistics**

**Need to perform **
**analysis with **
**anti-neutrinos **
**to completely **
**rule out LSND**

- Precise, well-defined neutrino/anti-neutrino beam
- with very high statistics and low backgrounds

- H. Ray

## Why the SNS?

- Tight beam window
- Small cosmic background
- ~107 beam off bkg in LSND vs ~3 / year @ SNS
- 72% pure  sample
- Decay-at-rest neutrino source
- extremely well defined flux and energy
- Hg+ + - = very low intrinsic neutrino backgrounds
- High statistics
- Max mixing # evts @ LSND  total = ~33K
- Max mixing # evts @ SNS in 1 year = ~49.5K

- H. Ray

## Why the SNS?

- When FNAL completes running in 2010 we will still need to learn more
- SNS : better defined E spectrum to allow precise measurements
- SNS : simultaneous measurements in neutrino, anti-nu modes
- SNS : different systematics to LSND, MB
- Second cross check of LSND
- SNS : can perform beyond the standard model searches not open to MB

- H. Ray

## Summary

- SNS is about to become the best neutrino based facility in the US
- DOE proposal for 2 near detectors awaiting funding
- LANL white paper produced for far detector
- Waiting on MiniBooNE result to go forward with a proposal
- Regardless of the outcome of MiniBooNE, the future of *precision* neutrino measurements in the US lies at the SNS!

- H. Ray

## Backup Slides

## Current MiniBooNE Status

- Neutrino energy distribution for a particular event selection based on Boosting PID variables
- Data points = High Energy open box

**High Delta m****2**** = 1.00, 0.004**
**Low Delta m****2**** = 0.4, 0.017**

- H. Ray

## Sterile Neutrino Oscillations

- Near detector : ~2056 events/year (25 ton)
- Far detector : ~3702 events/year (500 ton)

- + C   + C *
- C *  C + 15.11 MeV photon

- H. Ray

## Event Rates

- 250 ton detector @ 60 m

- H. Ray