# Presentation: 271250

## Reactor Neutrino Measurement of 13

**Reactor Neutrino Measurement of ********13**

- Karsten M. Heeger
*Lawrence Berkeley National Laboratory*

## 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?

## 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**

## Baseline Optimization for Detector Placement

*Optimize FAR detector with respect to NEAR*
**NEAR - FAR **	 0.1 km (fixed)   1.7 km

## Baseline Sensitivity to matm2 

- • Detector baselines sensitive to matm2.** **
- • Need option to adjust baseline once we have precision measurement matm2 .
- • Region of interest for current matm2 region:  Lfar=~1.5 - 3 km.
- • Optimize baseline to see oscillation signature in ratio of spectra.

## A 13 Reactor Experiment in the US ?

**Site Criteria**
**	****• ****powerful**** reactor**
**	****• ****overburden**** (> 300 mwe)**
**	****• ****underground**** tunnels or detector halls**
**	****• ****controlled access to site**

****** ****Variable/flexible baseline for *****optimization to ************m******2******atm***** and *****to demonstrate subdominant***** oscillation effect**
****** ****Optimization of experiment specific to site. Site selection critical **

## Diablo Canyon - An Ideal Site? 

- tunnel excavation required

- Diablo Canyon

*Ge*

- Issues
-  folding may have damaged rock matrix
- - steep topography causes landslide risk
-  tunnel orientation and key block failure
-  seismic hazards and hydrology

**Geology**

- I

- II

- IIIa

- IIIb

**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 found to be > 0)

- acrylic vessel

## Sites in France

**0.5 km**

**1.5 km**

** ****h=115 meters**

| Type  | PWR |
| --- | --- |
| Cores | 4 |
| Power | 11.8 GWth |
| Operator | EDF |
| Distances (km) | 1 / 1.8 |
| Overburden (mwe) | 150 / 500 |
| Volume @ Cruas | 20 t |

| Type  | PWR |
| --- | --- |
| Cores | 2 |
| Power | 8.3 GWth |
| Operator | EDF |
| Distances (km) | 0.4 / 1.5 |
| Overburden (mwe) | 200 / 200 |
| Volume @ Penly | 20 t |

**Penly**
** ****In Haute-normandie (north coast)**

**Cruas**
** ****In Ardèche (close to the Rhône)**

## Momentum in France

-  Muon Veto
-  V1 : Gd loaded scintillator
-  V2 : Unloaded scintillator
-  V3: Non-scintillating Buffer

- 20 tons

- Gd

**V****1**

**V****2**

**V****3**

**	****@********m2****atm****=2.10****-3**** eV2**
** ****	****sin****2****2****θ****13****<0.025 (90% C.L)**
**	****20 t , 3 years**

- Cruas

- Penly

**Laboratories involved:** PCC, Collège de France & CEA/Saclay
**Activities:** site evaluations, phenomenology, Detector simulation  ...

## Experimental Systematics

**Reactor Flux ****	****	**• near/far ratio, choice of detector location** **

- Best experiment to date: CHOOZ

**Target Volume &****	****	**• no fiducial volume cut
**Backgrounds ****	****	**• external active and passive shielding 						for correlated backgrounds

**Detector Efficiency****	**• built near and far detector of same design 					• calibrate *relative*  detector efficiency             					 *variable *baseline may be necessary

- Ref: Apollonio et al., hep-ex/0301017

- Total    syst   ~ 1-1.5%

*Note: list not comprehensive*

## Past and Present Reactor Neutrino Experiments 

## Future Diablo Canyon Experiment

## Sensitivity and Complementarity of 13 Experiments

- Sensitivity to sin2213

- Ref:  Huber et al., hep-ph/0303232

- sin2213 < 0.01-0.02 @ 90 C.L.
- within reach of reactor 13 experiments

- 10-1

- 10-2

- 10-3

**Reactor Neutrino Measurement of ********13**
- • No matter effect
- • Correlations are small, no degeneracies
- • Insensitive to solar parameters 12,m212

## 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*.*

## Parameter Degeneracy

**Complementarity of reactor neutrino measurements of ********13***** ***

- hep-ph/0211111

- observable effect of CP violation scales with 13* *

## Summary: Reactor Measurement of 13

- • 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*
- • 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 US power plants underway. Diablo Canyon is an attractive possibility.

**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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