# Presentation: 410894

## Reactor Neutrino Oscillation Experiments

**Reactor Neutrino Oscillation Experiments**

- Karsten M. Heeger
*Lawrence Berkeley National Laboratory*

## Recent Discoveries in Neutrino Physics

**Non-accelerator experiments have changed our understanding of neutrinos**

## Solar Neutrinos in the Big Picture

- Before 2002

## Search for Neutrino Oscillations with Reactor Neutrinos 

**50 Years of Reactor Neutrino Physics**
**1953 **First reactor neutrino experiment
**1956** *“Detection of Free Antineutrino”,*          F. Reines and C.L. Cowan
- 	 Nobel Prize in 1995
**No signature of neutrino oscillations until 2002!**

**Japan**

- Results from solar experiments suggest study of reactor neutrinos with a baseline of ~ 180 km

## KamLAND - Kamioka Liquid Scintillator Antineutrino Detector

- Uses reactor neutrinos to study  oscillation with a baseline of L ~ 140-210 km

## First Evidence for e Disappearance at KamLAND

- LMA parameters from:
- G.Fogli et al., PRD 66, 010001-406, (2002)

## KamLAND Neutrino Program

**Phase I: **
**Reactor and Geo Neutrinos**

-  oscillation search

- Terrestrial  detection

**Phase II: **
**Solar Neutrinos**

- Direct detection of 7Be 

- Solar e search, supernova detection,
- Nucleon decay

## Neutrino Oscillation Parameters

- Except for LSND, mij2 measured *and* confirmed.

## 13 and CP Violation

- atmospheric, K2K

**U****MNSP**** Neutrino Mixing Matrix**

- reactor and accelerator

- 0

- SNO, solar SK, KamLAND

- 12 ~ 30°

-  23 = ~ 45°

- tan2 13 < 0.03 at 90% CL

*maximal*

*large*

*small ... at best*

- No good ‘ad hoc’ model to predict 13.
- If 13 < 10-3 12, perhaps a symmetry?

- 13   yet to be measured
-         determines accessibility to CP phase

## Why Are Neutrino Oscillation Measurements Important?

**Central Questions in Neutrino Oscillation Physics ****& The Role of ********13**

- 1. What is the e coupling of 3 ? How large is 13?
- 	 13: an *opportunity for discovery*

- 2. What are 13, m231, CP, 12, m221, 23, m232?
- 		13: breaks correlation, helps with *determination of parameters*

- 4. Is there CP ?
- 	 13: *defines the future of accelerator **** experiments*

- 3. What is the  mass pattern?

**Physics at high mass scales, physics of flavor, and unification:**
- 	• Why are neutrino masses so small?
- 	• Why are the mixing angles  *large, maximal, and small*?
- 	• Is there CP violation, T violation, or CPT violation in the lepton sector?

## S. Glashow

- L. Wofenstein

- B. Kayser

- A. Smirnov

- S. Bilenky

## Reactor Neutrino Measurement of 13 - Basic Idea

- 13=?

- Reactor Neutrino Measurement of 13 - Basic Idea

- atmospheric frequency dominant
- last term negligible for 	             and

- Pee, (4 MeV)

- e flux* *

## Concept of a Reactor Neutrino Measurement of 13 

- Concept of a Reactor Neutrino Measurement of 13

- • No degeneracies
- • No matter effects
- • Practically no correlations
- E = Ee + mn-mp
- Eprompt = Ekin + 2me

## Reactor Neutrino Measurement of 13 

**Present Reactor Experiments**

**Absolute Flux**
**and Spectrum**

## Diablo Canyon - An Ideal Site? 

**Tunnel with Multiple Detector Rooms and Movable Detectors**

- ~12 m

- • Modular, movable detectors
- • Volume scalable
- • Vfiducial ~ 50-100 t/detector

- 1-2 km

## Detector Concept

- liquid scintillator

- buffer oil

- muon veto

- passive shield

**Detector Concept**

- 5 m

- 1.6 m

**Movable Detector? **	Variable baseline to control systematics and 				demonstrate oscillation effect (if |13| > 0)

- acrylic vessel

## Past and Present Reactor Neutrino Experiments 

## Future Diablo Canyon Experiment

## Future Constraints on 13  

| Experiment | sin2(213) | 13 | When? |
| --- | --- | --- | --- |
| CHOOZ | < 0.11 | < 10 |  |
| NUMI Off- Axis (5 yr) | < 0.006-0.015 | < 2.2 | 2012 |
| JPARC-nu (5 yr) | < 0.006-0.0015 | < 2.3 | 2012 |
| MINOS | < 0.06 | < 7.1 | 2008 |
| ICARUS (5 yr) | < 0.04 | < 5.8 | 2011 |
| OPERA (5 yr) | < 0.06 | < 7.1 | 2011 |
| KR2DET (Russia) | < 0.016 | < 3.6 | ? |
| Kashiwazaki (Japan) | < 0.026 | < 4.6 | [2008] |
| Penly/Cruas (France) | < 0.025 | < 4.5 | [2010] |
| Diablo Canyon (US) | < 0.01-0.02 | < 2.9 | [2009] |

- Upper limits correspond to 90% C.L*.*

## Diablo Canyon - An Initiative in California

**Science**
- Neutrino particle physics
- Reactor monitoring
- Geological studies
- Low-background counting
**... ****and Outreach**

## 50 Years of Scientific Discoveries at Reactors

**1956 **
- First observation of neutrinos

**1980s & 1990s **
- Reactor neutrino flux measurements in U.S. and Europe** **

**2002 **
- Discovery of massive neutrinos and oscillations

**2003 and beyond**Understanding the role of neutrinos in the universe

**Past Experiments**
- Hanford
- Savannah River
- ILL, France
- Bugey, France
- Rovno, Russia
- Goesgen, Switzerland
- Krasnoyark, Russia
- Palo Verde
- Chooz, France
- Reactors in Japan

**1995**
- Nobel Prize to Fred Reines at UC Irvine

## Measuring 13 with Reactors: Summary

- • Reactor neutrino oscillation experiment is promising option to measure 13.
- • Novel reactor oscillation experiment gives clean measurement of sin2213, no degeneracies, no matter effects.
*	**2 or 3 detectors, variable baseline*
*	**largely independent of absolute reactor flux and systematics*
- • Diablo Canyon offers possibility for geol. studies and low-backg. counting.
- • Sensitivity of sin2213 ~ 0.01 comparable to next-generation accelerator experiments. Complementary to long-baseline program. Allows combined analysis of reactor and superbeam experiments.
- • Negotiations with PG&E and the Diablo Canyon power plant are underway.

**http://theta13.lbl.gov/**

- Moderate Scale (~$40M)** ****	**Cost driven by tunnel excavation						Little R&D necessary (KamLAND, SNO, CHOOZ)**	****	****	****    ****	**Construction time ~ 2-3 yrs**	****	****	****	****	****    ****	****	**Start in 2007/2008?* *

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