# Presentation: 475361

## A New Experiment To Measure θ13

- David Reyna
- Argonne National Laboratory

## 3 Flavor Mixing Matrix

**CKM Matrix**

**MNS Matrix**

- David Reyna - ANL

- 10 March 2005

## Mixing Angles

- Matrix Components:
-   3 Euler Angles (θ12; θ13; θ23)
-    1 CP phase (δ)
-    (+2 Majorana Phases)

**Solar (****ν****e********ν****x****)**

**Atmospheric (****ν****μ********ν****x****)**

**The Next Big Thing?**

- David Reyna - ANL

- 10 March 2005

## Current Experiments

- First observed by Ray Davis and collaborators.  Measured  by Super-K, SNO and KamLAND.

- Measured by Super-K and confirmed by Soudan2 and K2K.

- Unconfirmed observation by LSND, currently being investigated by MiniBooNE.  Would require the existence of sterile neutrinos or CPT violation.

- David Reyna - ANL

- 10 March 2005

## Δm2 (aka: LSND problem)

- For 3 ν only 2 independent mass differences
- Mass hierarchy unknown

**(********m****2****solar****~ 7 x 10****-5 ****eV****2****)**

**(********m****2****atm****~ 2 x 10****-3 ****eV****2****)**

**Normal**

**Inverted**

******m****2**

**m****2**

**m****1**

**m****3**

**m****3**

**m****1**

**m****2**

- David Reyna - ANL

- 10 March 2005

## Current 13 Bound

**In currently allowed range   (****Δ****m****2**** =1.3-3 x 10****-3**** eV****2****)**
**sin****2****(2****θ****13****) < 0.19  ****@ 90% CL**

**Current Limits are set by experiments which were not trying to measure ****θ****13**
**Optimization of the experiments for this goal was never done**

- David Reyna - ANL

- 10 March 2005

## How to Measure 13 

- Appearance measurement
- Accelerator measurements look for small νe appearance in νμ beam
- P(esin2(213)sin2(23)sin2(m2atm L/4E)
- Disappearance measurement
- Reactor measurements look for small νe disappearance from large isotropic flux
- P(ee) =  1 - sin2(213)sin2(m2atm L/4E)

- David Reyna - ANL

- 10 March 2005

## Accelerator Difficulties

- Signature is electron appearance
- Requires massive detector with fine granularity (be able to distinguish e from P)
- Backgrounds
-  e in the beam, (~1%, from Ke3, K0e3)
- Fake e from e, (at high energy)
- Showers which look like e’s, particularly                                                                        , 
- Measurement has degeneracies due to  cp-violation and matter effects

- David Reyna - ANL

- 10 March 2005

## e Appearance in a beam

- P(e) = (2c13s13s23)2 sin2
- 
- 8c13s12**s****13**s23(c12c23coss12**s****13**s23)cos32sin31sin21
- 8c13c12c23s12 **s****13**s23sinsin32sin31sin21
- 4s12c13(c12c23s12s23**s****13**c12c23s12s23**s****13**cossin221
- c13**s****13**s23**s****13**aLEcos32sin31

****

- 

- 

- 

- 

- 

- 

- 

- 

****

- 

****

- 

- a = constant X neE

-  CP violating

- CP: a-a, 

- David Reyna - ANL

- 10 March 2005

## 

**sin****2****2********13**

- There are 2 Observables
- P(e)
- P(e)
- Interpretation in terms of sin2213,  and sign of m223 depends on the value of these parameters and on the conditions of the experiment: L and E

- Minakata and Nunokawa, hep-ph/0108085

- Understanding the Degeneracy

- David Reyna - ANL

- 10 March 2005

## Experimental Solutions

- If θ13 is large, the degeneracy can be broken with Off-Axis measurements
- Measure both ν and anti-ν rates
- Multiple experiments with different baselines and different energies
- Will yield a rich physics program for cp-phase and mass hierarchy
- If θ13 is zero, degeneracies collapse but there’s no attainable physics gain
- Big cost - big risk

- David Reyna - ANL

- 10 March 2005

## P(ee) = 1 - sin2 213 sin2(m2atm L/4E)                 		     - cos413 sin2 212 sin2(m2sol L/4E) 

- The Reactor Measurement

- P

- L/E(km/MeV)

**atmospheric**

**solar**

- No CP-violation in a disappearance measurement
- Distance (~1Km) is too short for matter effects

- David Reyna - ANL

- 10 March 2005

## Previous Reactor Measurements

- All measure the same energy spectrum.
- Previous experiments used single detector and were limited by 3% uncertainty in reactor power.
- KamLAND is first to see positive evidence of oscillation.
- Future experiments propose 2+ detectors of 10-100 tons (not kilotons).

- KamLAND sees a 40% deficit/shape at 200km related to m212
- Search for a 1-5% deficit/shape at ~1 km related to m213

- David Reyna - ANL

- 10 March 2005

## How to Detect a e Event 

- How to Detect a e Event

- David Reyna - ANL

- 10 March 2005

## Reactor ’s

- Reactor ’s

- Reactors provide a fairly steady flux of  1-10 MeV ’s
- Neutrino energy carried by positron
- 	Eν = Ee+ + 0.8 MeV
- Adding Gd moves     n-capture peak from 2.2 MeV to 8 MeV and reduces capture time to ~10μs

*‡ **from Palo Verde*

- David Reyna - ANL

- 10 March 2005

## The Double Chooz Concept

**8.4 GW****th**
**Chooz PWR power station**

**Near detector**

**Far detector**

******e**

******e,********,******

** ****D****1**** = 100-200 m**

**D****2**** = 1,050 m **

- Measure neutrino flux before and after oscillation
- Measure difference from 1/r2 dependence
- Improve detector design to reduce systematics

- David Reyna - ANL

- 10 March 2005

## Who is Double Chooz?

**Saclay, APC, Subatech, TUMunich, MPIK-Heidelberg, Tubingen Univ., Univ. Hamburg, Kurchatov, LNGS, Lousiana State, Argonne, Drexel **
**Univ. Alabama, Univ. Notre Dame, Kansas State, Univ. Tennessee**

- David Reyna - ANL

- 10 March 2005

## EdF Has Approved Access to All Sites

- David Reyna - ANL

- 10 March 2005

## Far      Near Sites

_**60 m.w.e. overburden**_
- 12 m compacted earth
- 3 meter high density material

**DAPNIA**

- David Reyna - ANL

- 10 March 2005

## Reactor Challenges

- Long term stability (Liquid Scintillator)
- Chooz/Palo Verde were few month exp’s
- Next generation must be 3-5 years
- Backgrounds
- Chooz measured ~10% with reactor off
- Unlikely to duplicate reactor off data
- Systematic Error Control
- Consistency of mechanical construction
- Previous exp’s were 2-3% (excluding reactor)
- Needs to be 1% or less

- David Reyna - ANL

- 10 March 2005

## Long Term Stability (Liquid Scintillator)

- Gd doping has resulted in poor stablity of liquid Scintillator
- Palo Verde had problems with precipitation/condensation
- Mystical fix with water vapor
- Chooz saw a very rapid decay of attenuation length
- Heidelberg and LNGS (LENS/Borexino) have been working for the last 3-5 years to understand these effects
- Simple dissolved Gd solutions are very sensitive to pH
- Attempting to bind Gd into the chemical structure of the liquid

- Eur.Phys.J. C27 (2003) 331-374

- David Reyna - ANL

- 10 March 2005

## Gd doped scintillator

- Gd-Acac
- Gd-Dmp

- 3+Gd

-  Gd-Carboxylate

**Solvant: 20% PXE – 80% Dodecane**
**Gd loading: 3 recipes developed @Heidelberg & LNGS**
**Gd-CBX **
- Good stability @20oC
- Suitable baseline – End of development
**Gd-Acac **
- Good stability @20oC
- Low solubility in PXE  warning
- Difficult to purify
**Gd-Dmp **
- Good stability @20oC
- High solubility in PXE+dodecane
- OK for purification
- Synthesis to optimize

**6 g/l PPO**
**20 mg/l BisMSB**

**LY~8000 ********/MeV **
** ****L = 5-10 m**

- David Reyna - ANL

- 10 March 2005

## 20C - long period test
All Gd-CBX,Acac, Dmp are stable
Yb sample stable since 4,5 years 
     (small sample)
In sample stable since 1,5 years 
     (2 liters, 1 year meas. @LNGS)

- All Gd-CBX,Acac, Dmp are stable
- Yb sample stable since 4,5 years
-      (small sample)
- In sample stable since 1,5 years
-      (2 liters, 1 year meas. @LNGS)

** ****Gd-CBX**

- Gd-Acac Heidelberg

- Gd-CBX (test in Saclay)

- Gd Doped Scintillator Aging Tests

- High Concentration Test
- LENS R&D: Yb, Gd, In  2 In-sampled loaded at 5% measured for 1 year @ LNGS and found stable (10-20% error)
-  6 month 1% Gd-CBX Stable  work in progress
- High Temperature Test
- 40C for several weeks to accelerate aging
- Still under investigation
- Next Step: large scale production and stability test

- David Reyna - ANL

- 10 March 2005

## Backgrounds

- correlated background

- accidental background (uncorrelated)

- +-n cascades

- Accidental Backgrounds
- Mainly at Low E
- Best measurement from Borexino(CTF)
- Must reduce few MeV radioactive sources and thermal neutrons
- Correlated Backgrounds
- Mainly from cosmic muons
- Best measurements from KamLAND but hard to extrapolate to shallow depth
- Must reduce overall muon rate and attempt to veto background candidates

- David Reyna - ANL

- 10 March 2005

## Cosmic muons create fast neutrons 
Spallation in the rock surrounding the detector
Muon capture in the detector materials
Fast neutron slows down by scattering into the scintillator (depositing energy) and is later captured on Gd !
Full simulation – Geant + Fluka
Old Chooz configuration: 300 m.w.e. 31hours – to validate MC 
Simulated: Nb<1.6 evts/day (90% C.L.)
Measured in-situ: Nb=1.1 evts/day
Double-Chooz configuration:
338 106 μ tracked – 580 103 neutrons tracked
1 neutron created a background event
Far detector expectation: 	        Nb<0.5 evt/day (90% C.L.)
Near detector expectation:        Nb<3.2 evts/day (90%C.L.)

- Cosmic muons create fast neutrons
- Spallation in the rock surrounding the detector
- Muon capture in the detector materials
- Fast neutron slows down by scattering into the scintillator (depositing energy) and is later captured on Gd !
- Full simulation – Geant + Fluka
- Old Chooz configuration: 300 m.w.e. 31hours – to validate MC
- Simulated: Nb<1.6 evts/day (90% C.L.)
- Measured in-situ: Nb=1.1 evts/day
- Double-Chooz configuration:
- 338 106 μ tracked – 580 103 neutrons tracked
- 1 neutron created a background event
- Far detector expectation: 	        Nb<0.5 evt/day (90% C.L.)
- Near detector expectation:        Nb<3.2 evts/day (90%C.L.)

- Neutron Induced Background

- David Reyna - ANL

- 10 March 2005

## β-neutron Cascades (Cosmogenics)

-  crossing the detector
- Likely to be seen by the Veto

- 8He    9Li     11Li

- β decayed followed
- by n emission within 200 ms !
- (not veto-able)

-  **μ**** interaction  on ****12****C**

- David Reyna - ANL

- 10 March 2005

## Chooz Backgrounds

- Large singles rate
- PMT glass in scintillator
- Used vertex cut to reduce effect but with increased systematic error
- New detector design will eliminate this effect
- Took data with all reactors off
- Allowed direct measurement of correlated backgrounds
- Consistent with other analysis methods for eliminating backgrounds
- Known environment for future experiment

- Eur.Phys.J. C27 (2003) 331-374

- David Reyna - ANL

- 10 March 2005

## Background Estimates

**Chooz ****	****	****(300 mwe) ****	****5.5 m****3****, Noise/Signal ~ 4%**
- Correlated events (neutrons):
- Chooz : ~1 recoil proton per day** **
**Double-Chooz-Far ****	****(300 mwe)****	****12.7 m****3****, Signal  x 2.4**
- Uncorrelated (, + n capt. on Gd):	Sx3 & N/3  can be subtracted
- Correlated events (neutrons):
- Goal <1 events per day  + known spectrum   N/S<~1%
- Correlated events (cosmogenics)
**Double-Chooz-near ****	****(60 mwe) ****	****12.7 m****3****, Signal x 30-50 S****FAR**
- Key advantage: Dnear~150 m  Signal x ~30-50
- Uncorrelated: Chooz-Far backgrounds x 50  can be subtracted
- Correlated events: Chooz-Far x <30  N/S < 1%
- Correlated events (cosmogenics)
- (but not a comprehensive list of backgrounds ...)

- David Reyna - ANL

- 10 March 2005

## Additional Outer Veto at Near Detector

| Simulated Veto Efficiency (55 Million Events) |  |  |
| --- | --- | --- |
| 36283 | Events with Target Neutron | (%) |
| 21552 | No Muon in Target | 0.6 |
| 2218 | No Inner Veto Muon | 0.06 |
| 1174 | No Outer Veto hit on top | 0.03 |
| 46 | With no Outer Veto Hit | 0.001 |

- David Reyna - ANL

- 10 March 2005

## New detector design

- 7 m

- 7 m

- David Reyna - ANL

- 10 March 2005

## Systematic Breakdown

| Error Source | Palo Verde | Bugey 
Abs Norm | Bugey
Rel Norm |
| --- | --- | --- | --- |
| Neutrino Flux | 3.3 | 2.8 | - |
| νP Cross Section | 1.0 | 0.2 | - |
| Solid Angle | 0.3 | 0.5 | 0.5 |
| Target Protons | 1.3 | 1.9 | 0.6 |
| Neutron Detection | 2.0 | 3.2 | 1.5 |
| Positron Detection | 2.0 | 0.9 | 0.9 |
| Selection Correlation | 1.9-4.5 | 1.0 | - |
| Background | 3.5-3.9 | ‡ | ‡ |
| Total | 5.3-6.9 | 5.0 | 2.0 |

- 25  @ 15m
- ‡ Signal/Background = 2.2 @ 40m
- 0.7 @ 95m

- David Reyna - ANL

- 10 March 2005

## Detector Relative Comparison

**Solid angle**
- Distance measured @10cm + Monitoring of the  source barycenter  ...
**Target volume**
- @CHOOZ : 0.3% [simple measurement]
- Goal ~0.2% [same apparatus for both detectors] –
- Test - scale 1 - in progress
**Density**
- 0.1% achievable, but accurate temperature control mandatory
**H/C ratio & Gd concentration**
- Absolute measurement is difficult : 1% error @CHOOZ
- Plan: use the same batch to fill both detectors
**Boundary effect at the inner vessel interface (spill in/out)**
- Neutron transport slightly different due to solid angle effect
**Live time** **to be measured accurately by several methods**

- David Reyna - ANL

- 10 March 2005

## Relative Normalization: Analysis

- e+

- n

- t

- @Chooz: 1.5% syst. err.
- 7 analysis cuts
- Efficiency ~70%
- Goal Double-Chooz: ~0.3% syst.  err.
- 2 to 3 analysis cuts
- Selection cuts
- neutron energy
- distance (e+ - n ) [level of accidentals]
- t (e+ - n)

- David Reyna - ANL

- 10 March 2005

## How Good is Good Enough?

- David Reyna - ANL

- 10 March 2005

## Understanding Mechanical Construction

**Acrylic** **Target vessel**
**(R=1,2m,**
**h=2,8m,**
**t = 12mm)**

**Stainless steel Buffer**
**(R= 2,75m,**
**h = 5,6m,**
**t = 4mm)**

**Muon VETO**
**(shield)**
**Thickness = 150mm**

**Acrylic Gamma catcher vessel**
**(R = 1,8m,**
**H = 4 m,**
**t = 8mm)**

**LS + 0,1%Gd**

**LS**

- David Reyna - ANL

- 10 March 2005

## Acrylic selected
Material compatibility test ongoing
(OK with Security Factor = 8)
Prototype 1/5 by june 2005
(call for bid sent)

- Material compatibility test ongoing
- (OK with Security Factor = 8)
- Prototype 1/5 by june 2005
- (call for bid sent)

-  A special Tool will be developed to rotate/insert the acrylic vessel into the pit after PMT mounting

**CEA/DAPNIA**

**Test of accessibility in Chooz tunnel with acrylic vessel model**

- Acrylic Integration

- David Reyna - ANL

- 10 March 2005

## Mechanical Studies

| Vessel | Dimension | Distortion | Stress |
| --- | --- | --- | --- |
|  | Inputs :
Target thickness = 8 mm
 catcher thick. = 12 mm
E = 2.7 GPa
Elastic limit : ~80 MPa 

Loads = dead load | Max. distortion : <1  mm | Max. VM stress: 1 MPa |
|  | Inputs :
Thickness = 4 mm
E = 210 GPa
Elastic limit: 205 MPa 

Loads = 2 kg / pmts
 acrylic vessels weight
 dead load | Max. distortion : 4.1 mm | Max. VM stress: 23 MPa |

- David Reyna - ANL

- 10 March 2005

## Scale (1:5) Prototype 

**Acrylic** **Target Vessel**

**Stainless Steel Buffer**

**Muon VETO**

**Acrylic Gamma Catcher Vessel**

**LS + 0,1%Gd**

**LS**

**Goal: technical solutions for construction and integration**

- Scale (1:5) Prototype

**PMT Cable Routing**

- David Reyna - ANL

- 10 March 2005

## Additional Work Ongoing

- PMTs
- Testing radioactivity
- Mounting systems
- Electronics/HV
- Prototype designs are under study
- DAQ system is under design
- Calibration
- Fiber Optic/LED system
- Articulated arm vs. Rope-and-Pulley development
- Wire driven Guide Tubes for Gamma Catcher
- Radioactive source development
- Simulation
- Full G4 Detector Simulation (derivative of  KamLand)
- Complete optical properties
- All Chemical Properties
- Muon/fast neutron in G4 and FLUKA
- Feeding back the R&D into the simulation effort
- Non-Proliferation
- Collaboration with LLNL and IAEA
- Interest in monitoring reactor power and fuel composition

- David Reyna - ANL

- 10 March 2005

## Status of Double Chooz (Europe - I)

- EDF has agreed to the project
- Allow use of the original laboratory
- Agreed to location for near laboratory 		 (150-200 meters from core)
- French funding agency has approved the project
- Provide 1⁄2 the funding for detector construction
- Agreed to fund the construction of the near laboratory
- Awaiting complete engineering analysis and costs from EdF
- Contracts for prototype construction are already under negotiations for bids
- MPI-Heidelberg is providing independent funding for Liquid Scintillator development and production

- David Reyna - ANL

- 10 March 2005

## Status of Double Chooz(Europe - II)

- Germany still has other institutions seeking ‘normal’ funding
- 5 year cycle but they are in the queue
- Italy is working on LS but has no funding
- Rumors that the canceled BTeV may free up Italian money
- Russians have agreed to produce radioactive sources but little money is expected

- David Reyna - ANL

- 10 March 2005

## Status of Double Chooz(U.S.)

- Submitted proposal to DOE in October ‘04
- $4.8M over 3 years for total project
- Already secured forward funding of $3M
- DOE has decided to not decide
- Establishing neutrino SAG
- Double Chooz Construction Proposal competes 	   with R&D requests from Braidwood and Daya Bay
- US groups are continuing to finalize design work on expectation of approval
- New groups are continuing to join
- Recent additions of Los Alamos and Livermore

- David Reyna - ANL

- 10 March 2005

## Expected Schedule

- Detector Construction
- Can begin in 2006 (No known reason for delays in construction and installation of far detector)
- Near Laboratory
- Finalize designs in 2005
- Hope to have civil construction 2006-7
- Install near detector at end of 2007 or early 2008
- Data Taking
- Can begin taking data with far detector as soon as it is installed (middle 2007)
- Near detector will hopefully follow in 16 months

- David Reyna - ANL

- 10 March 2005

## Expected Sensitivity 2007-2012

**Far Detector starts in 2007**
**Near detector follows 16 months later**
**Double Chooz can surpass the original Chooz bound in 6 months**

- 90% C.L. contour if sin2(213)=0
- m2atm = 2.8 10-3 eV2 is supposed to be known at 20% by MINOS

- David Reyna - ANL

- 10 March 2005

## Double Chooz Complements Off-Axis

- A positive signal within the Double Chooz range would signify a very rich program at the accelerator measurements
- A null result would imply a difficult path
- Double Chooz is the only experiment which can provide such a direct result in a short time period 	(~3-4 years)

**Sensitivity regions for resolving the Mass Hierarchy at 2******** (with Proton Driver)**

- from M. Shaevitz

- David Reyna - ANL

- 10 March 2005

## Conclusion & outlook

- Strong Collaboration
- Saclay, APC, Subatech, TU Munich, MPIK-Heidelberg, Tubingen Univ., Univ. Hamburg, Kurchatov, Lousiana State, Drexel, Argonne, Univ. Alabama, Univ. Notre Dame, Kansas State, Univ. Tennessee, LNGS
- Experience from Chooz, Palo Verde, KamLAND, Borexino, LENS
- Known Technology
- Conservative design (incremental improvement on Chooz)
- Reasonably achievable improvements in detector systematics
- Known Environment
- Direct comparison to previous Chooz results / backgrounds
- Excellent Physics Opportunity
- Current Chooz bound is sin2(213)<0.19 @ 90% C.L
- Expect sensitivity of sin2(213)<0.02-0.03 with 3 to 5 year run
- Continuing to maintain aggressive schedule
- Price is right!

- David Reyna - ANL

- 10 March 2005