Double Chooz - Kansas State Universityneutrino.phys.ksu.edu/~gahs/doublechooz/PASCOS-2005.pdf ·...

G. Horton-Smith, KSU, Double Chooz June 1, 2005, PASCOS '05

PASCOS 2005

Double Chooz:a double fast experiment

to measure the neutrino mixing parameter θ13

Glenn Horton-SmithKansas State University

Double Chooz collaboration


Double Chooz collaboration(not quite up to date)

Florence Ardellier, Igor Barabanov, Steve Berridge, L.B. Bezroukov, Maurizio Bonesini, Janine Boucher, Christian Buck, William Bugg, Anatael Cabrera, Carla Cattadori, Bernard Courty, Michel Cribier, Olivier Dadoun, Ferenc Dalnoki-Veress, Nikolay Danilov, Steven Dazeley, Alain De Bellefon, Herve de Kerret, Assunta Di Vacri, Yuri

Efremenko, Alexandre Etenko, Muriel Fallot, Marianne Goeger, Maury Goodman, Christian Grieb, Arnaud Guertin, Caren Hagner, Wolfgang Hampel, Frank Hartmann, Glenn Horton-Smith, Claude Jeanney, Josef Jochum, Yuri

Kamyshkov, Jerome K. Busenitz, Thomas Kirchner, Yuri Krylov, Didier Kryn, Tobias Lachenmaier, Chuck Lane, Thierry Lasserre, Christian Lendvai, Alain Letourneau, David Lhuillier, John LoSecco, Fredecric Marie, Jacques

Martino, Igor Matchouline, Guillaume Mention, Emanuela Meroni, Bill Metcalf, Jean-Pierre Meyer, Alain Milsztajn, Dario Motta, Lothar Oberauer, Michel Obolensky, Luciano Pandola, Giancarlo Piredda, Walter Potzel, David Reyna, Andrew Sabelnikov, Stefan Schoenert, Ute Schwan, Sahbi Selmane, Hardy Simgen, Mikhail Skorokhvatov, Serguey

Soukhotine, Ion Stancu, Bob Svoboda, Jonathan Thron, Antonin Vacheret, Matthieu Vatre, Daniel Vignaud, Franz Von Feilitzsch, Evgeni Yanovich, Karim Zbiri, Raoul Zimmerman

● France: APC, DAPNIA, Subatech-Nantes● Germany: EKU-Tubengen, MPIK Heidelberg,

University of Hamburg, TUM (Munich)● Italy: INFN (Assergi & Milano), University of l'Aquila● Russia: Kurchatov Institute, RAS● USA: Alabama, ANL, Drexel, Kansas State, LSU, Notre

Dame, Tennessee


What I will tell you

● Some brief review● Experimental strategy, location, and some details● Sensitivity goal● Schedule


Totally unnecessary reminder: neutrino mixing matrix

[ |e>|>|> ]=[U e1 U e2 U e3

U 1 U 2 U 3

U 1 U 2 U 3] [ |1

|2|3 > ]


Reminder: the mixing angles

[ c12c13 ei1 /2 s12c13 e

i 2 /2 s13 e−i

−s12c23c12 s23 s13eie i1/2 c12c23−s12 s23 s13 e

i e i 2 /2 s23c13

s12 s23−c12c23 s13eie i1/2 −c12 s23s12c23 s13 e

i e i 2 /2 c23c13]≃[ 0.8 0.5 ?

−0.4 0.6 0.70.4 −0.6 0.7 ]

where cij=cos ij , sij=sin ij , is the CP-violating Dirac phase, and 1 ,2 are CP-violating Majorana phases.

θ12 = 33º±3º solar observations (SK, SNO) [+KamLAND input]

θ23 = 45º±7º atmospheric and accelerator (SK, K2K, MINOS)

θ13 < 13º reactor experiments (CHOOZ, future)sin(θ13)eiδ = ? accelerator (NOVA, T2K)

α1, α2 = ?? [neutrinoless double beta decay?]


Reminder: what mixing does

νe

νµ

ντ

L/E (km/MeV)

KamLANDEe+ > 2.6 MeV cut

P e e=1−sin2 212 sin2 m122 L

4 E

“Solar” delta mass-squared (8.2+0.6-0.5)×10-5 eV2.

Mixing angle θ12 = 33º±3º.


Reminder: The basic strategy

Source

Neutrino detector observesrate and spectrum.

Analyze deficit or appearanceto look for oscillation.


I just can't resist talking about KamLAND a bit

53 reactor cores, power ~3 GWth/core,at typical baseline of 180 km, provideexpected no-oscillation rate of about1 event per kiloton-day at KamLAND.


KamLAND L0/E plotPRL 94, 081801 (2005)


“Atmospheric” ν oscillationsP =1−sin2 223 sin2 m23

2 L4 E

13=0 case

νe

νµ

ντ

L/E (km/GeV)

Atmosph. ν,ν beams


1-3 oscillation modeP e e≃1−sin2 213 sin2m13

2 L4 E

, form12

2 L4 E

≪1

νe

νµ

ντ

L/E (m/MeV)

νµ beam, νe detector(NOνA, T2K)

Reactor experiment:νe “beam”, νe detector


Cosmological relevance?● “Leptogenesis”, a possible explanation of matter-

antimatter asymmetry, requires CP violation in the neutrino sector.

● CP violation can't be found in neutrino oscillations if θ13

is non-zero.● Does this mean that if θ13 is non-zero, then we can prove

or disprove leptogenesis with NOVA or T2K?● Sadly, no: the CP violation we can probe in these

experiments is not, in general, the CP violation needed in leptogenesis. (Some do models connect the two.)


Neutrinos on trial?

“Nonetheless the observation of CP violation and neutrinoless double beta decay would provide

strong circumstantial evidence for leptogenesis...

Even though we may not be able to convict leptogenesis in a criminal trial, we may still find it

guilty in a civil case.”-APS Neutrino Study, Astrophysics and

Cosmology working group

(Gee, I didn't realize breaking matter-antimatter symmetry was a crime...)


Aside: Why do so many questions related to our origins go to court, anyway?

In the beginningthe Universe was created.

This has made a lot of people very angry and been widely

regarded as a bad move.-Douglas Adams


Reactor antineutrino disappearance experiment

P e e≃1−sin2 213 sin2m132 L

4 E

, form12

2 L4 E

≪1

νe

L/E (m/MeV)

θ13 = 0.1sin22θ13= 0.04∆m2

13 =.0025 eV2

L=1 kmE=2~6 MeV


History of reactor neutrino experiments


Current best limit from CHOOZ experiment

Sin22θ13 < 0.19 (90% CL at 2.0 10-2 eV2)

νep→e+n; Neutron/positron coincidence

200 days reactor on; 142 days reactor off

Stopped due to systematic error of reactor flux

Palo Verde

Chooz

SK allowed sin22θ13 (90% CL)

sin22θ13

∆m

2


The new strategy in brief

Reactor

Near detector observestrue rate and spectrumwith almost no oscillation effect.

Far detector observesrate and spectrum withoscillation effect dominatedby θ13.

Reduce the systematic errors that limited past reactor experiments (mainly neutrino absolute flux and spectrum shape) by using two detectors, one “near” and one “far” from the reactor neutrino source.


Several proposals

● KR2Det, Siberia (defunct)● Diablo Canyon, California (killed)● KASKA, Japan (never say die!)● Double Chooz, France● Braidwood, Illinois● Daya Bay, China● Angara, Brazil● Korea?


The Chooz site

To be built:Baseline ~ 150 mOverburden ~ 60 mwe

Ready to be used:Baseline ~ 1100 mOverburden ~ 300 mwe


The logo explained

Meuse river“C” “H”

Near and far detectors“OO”

νe and νx

“Z”


More photos of Chooz site

Chooz-near

Chooz-far

2 x 4200MW Reactors

1100m Baseline300MWE Overburden


Improvements over CHOOZ

● Improved detector design.● New and improved scintillator.● Active inner and outer veto systems.● Near detector.


Improved detector design

Gamma catcher: scintillator with no Gd

7 m

7 m

BUFFER Mineral Oil with no scintillator

7 m

Shielding steel and external vessel(studies, réalisation, intégration IN2P3/ PCC)

Target- Gd loaded scintillator (12.3 m3)

Modular Frame to support photomultipliers (UT)

Optically separated inner veto to tag muons

Nested 3-layer design reducesdetector edge effects while maintainingoptimal shielding against external backgrounds. Target volume is actually bigger than original CHOOZ.


Acrylic Vessel Design✔ The full detector will be

3.6 m (d) x 4 m (h)

✔ 1/5th scale prototype is under construction

Deformation analysis from Saclay


New and improved scintillator

Degradation of the attenuation length caused trouble for CHOOZ.

After several years of research, MPI-Heidelberg has developed more optically stable Gd loaded oils: one carboxylic, one beta-diketones.

Currently producing 200 L. They will optimize this

scintillator and provide for Double Chooz. 390 420 450 480 510 540 570 600

0,040,060,080,100,120,140,160,18

abso

rban

ce

wavelength [nm]

Sep 03 Nov 03 Feb 04 Apr 04 Aug 04 Okt 04

λ

t


Near hall conceptual design

Lnear ~100 meters, the closest near detector of any proposed experiment

Fiducial detector and gamma catcher identical to far det.~60 m.w.e. deep.Additional outer veto & larger inner veto for cosmogenic background suppression.


Active veto systemsInner veto tags muons near detector

The Outer Veto provides additional tagging of µ induced background n’s.

Prototype counters designed/tested A Fluka simulation of µ’s at the near detector is being used to specify needed coverage


Phototubes

₪ Baseline – 1040 tubes₪ 12.9% phototube coverage₪ 190 pe/ MeV (Monte Carlo)

╬ PMT related backgrounds were about 1/3 BG at CHOOZ

╬ Recent work on• Cabling schemes• Sensitivity to B fields• Angular sensitivity• Tilting tube options• Phototube comparisons• Radioactivity measurements

╬ PMT’s must be ordered by this fall to maintain the “rapidly deployed” schedule.


Calibration systems

In the Central Target Region,an Articulated Arm provides

– Positioning Resolution/Precision

– Total Coverage

In the Gamma Catcher, wire driven sources in guide tubes can provide calibration

Articulated arm design Wire source Wire driver


Signal

● A good number to remember for reactor neutrino experiments is ≈ 1 event/(GWth-ton-day) @ 1 km.

● Far detector is 12.3 m3, 0.8 ton/m3, 1 km from 2 cores, 4.2 GWth/core ==> ~80 events/day. (!)

● Identical near detector 100~140 m from cores, 4000~8000 events/day. (!!!)


Backgrounds

☼ Near detector overburden is chosen to keep signal/background above 100

☼ Largest background before muon tagging is fast neutrons; efficient inner and outer veto can reduce them considerably.

☼ Largest uncertainty in background comes from spallation of Li9 ☼ Backgrounds measured at CHOOZ used to calculate sensitivity

Detector Signal 9Li n n-accid. total BG S/B δB/Sfar 80 < 1.7 0.5 0.2 < 2.4 >30

±0.3 - - ±0.3 0.004near >4000 < 17 5 2 < 24 >160

±3~10 - - ±3~10 <0.003


γ backgrounds under control

1.0E-08

1.0E-07

1.0E-06

1.0E-05

1.0E-04

1.0E-03

1.0E-02

1.0E-01

1.0E+00

1.0E+01

50.00 100.00 150.00 200.00 250.00 300.00 350.00 400.00

Radius, cm

Rat

e, H

z in

cm3

Scintillator γ - Catcher Veto Sand Rock

ChoozChooz

Steelγ - Catcher

DChoozDChooz

PMTs

Vessel

Acrylic

RockVetoBufferScintillator


Systematics

<0.6%0.6%Total

<0.2%0.3%Distance Cut

0.1%0.1%Acquisition

<0.25%0.25%Dead Time (veto)

0.1%0.1%Time cut

negligiblenegligibleSpatial Effects

0.2%0.2%Neutron Energy

0.1%0.2%Neutron Efficiency

0.1%0.1%Ratio H/C

0.1%0.1%Density

0.2%0.2%Volume

0.2%0.2%Solid Angle

Double ChoozAfter CHOOZ


Sensitivity

Original ChoozDetector ErrorDouble Chooz goal

(I will show sensitivity vs. time next)


Projected schedule:sensitivity vs. time

Far detector only

Far & Near detectorstogether

05/2007 05/2008 05/2009 05/2010

σsys=2.5%

σsys=0.6%Far detector

onlyFar & Near detectors

together

05/2007 05/2008 05/2009 05/2010

σsys=2.5%

σsys=0.6%

● 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 ifsin2(2θ13)=0.

● MINOS is supposed tell us ∆m2

atm to 20% by then.


Comparison with “incomplete selection” of predictions

The nominal 90% CL sensitive region of Double-CHOOZ is shown in yellow.


Connection between reactor and accelerator experiments

● Many people have made lots of plots, but the one I like is the plot of the directly measured experimental quantities: νe appearance in the accelerator beam versus νe disappearance from the reactor flux.

● If you don't like these plots, you can find lots of others in the APS neutrino study, in any number of papers, proposals, etc., etc.


Connection with long baseline accelerator experiments

Acc

eler

ator

-bas

ed ν

e app

eara

nce

resu

lt

Reactor-based νe disappearance result

DC 2010(+/- 0.02)

DC 2010(< 0.03)


Connection with long baseline accelerator experiments

DC 2010(+/- 0.02)


Conclusions

● Double Chooz is moving forward rapidly.● Double Chooz will make a fast measurement or

limit on θ13 to order sin22θ13 ~ 0.03.● This is a valuable contribution:– will improve knowledge of PMNS matrix;– might give “circumstantial evidence” supporting

leptogenesis;– will guide later experiments.

Double Chooz - Kansas State Universityneutrino.phys.ksu.edu/~gahs/doublechooz/PASCOS-2005.pdf ·...

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