Double Chooz Experiment Status Double Chooz Experiment Status Jelena - - PowerPoint PPT Presentation

Double Chooz Experiment Status Double Chooz Experiment Status

Jelena Maricic, Drexel University (for the Double Chooz Collaboration) (for the Double Chooz Collaboration) S t b 27th SNAC11 September, 27th, SNAC11

Double Chooz Collaboration

Outline

• Neutrino detection and 13

measurement O i f th D bl Ch

• Overview of the Double Chooz

detector

• DC far preliminary data
• Antineutrino anomaly and

consequences for Double Chooz

• Summary and outlook

NEUTRINO DETECTION AND 13 MEASUREMENT

Reactor Neutrino Detection Signature

• Reactors as neutrino sources:

N

1

  6N

1

 

2 1011P

1

 

N s1

  6NFiss s1   2 1011P s1  

Chooz: P =2x4.25 GWth N~2x1021s‐1

th 

Neutrino detection via inverse  decay Target: Distinctive two‐step signature: ‐prompt event Photons from e+ annihilation g Gd doped scintillator Photons from e annihilation Ee = E+ 0.8 MeV + O(Ee/mn) ‐delayed event Ph t f t 1 g/l Gd Photons from n capture on dedicated nuclei (Gd) t ~ 30 s E ~ 8 MeV Gadolinium in LS

• J. Maricic‐Double Chooz

5

Gadolinium

Site in French Ardennes

300 mwe Hill topology East Reactor West Reactor

Started 12/10

West Reactor

Physics data taking 04/11

351 m 465 m

France

115 mwe Flat topology

6 Jelena Maricic, Drexel U

Start in early 2013

The ‐ New – Concept – 2 detectors

P(e e) = 1 ‐ sin2(213) sin2(m2

31L/4E)

( e

e)

(

13)

(

31 /

)

Background reduction Background reduction and calibration are very important

E = 1‐8 MeV Pure e flux

e,,

e e,µ,τ

400 m Nuclear Power Station Near detector Far detector 1050 m

7 Jelena Maricic, Drexel U

Far to near detector signal ratio will give information about θ13

Expected Neutrino Oscillation Signal

Two independent sets of information: sin2(213)=0 04

ars

Two independent sets of information: Normalisation + Spectrum distortion Far/Near ratio sin (213)=0.04 sin2(213)=0.1 sin2(213)=0.2

ents/200 KeV/3 yea

Far/Near ratio F D t t ~

Eve E (MeV)

Far Detector: ~ 40 000events/3y ‐Reactor efficiency: 80%

sin2(213)=0.12 m2

atm= 3.0 10‐3 eV2

Near Detector: ~ 5 105events/3y Reactor efficiency: 80% ‐Detector efficiency: 80%

E (MeV)

• J. Maricic‐Double Chooz

8

‐Reactor efficiency: 80% ‐Detector efficiency: 80% ‐Dead time: 50%

arXiv: hep‐ex/0606025v4

7 m

4 concentric vessels l

7 m

Neutrino target vessel in the center

• J. Maricic, Drexel U

9 http://doublechooz.in2p3.fr/

Courtesy of T. Lasserre

7 m

The detector design

Near and far detectors are IDENTICAL.

7 m

Muon Outer‐VETO: ‐catcher: 80% dodecane + 20% PXE

Extra volume for  interaction

‐target: 80% dodecane + 20% PXE + 0.1% Gd

Volume for ‐interaction (d = 2.3 m, h = 2.8 m) Extra‐volume for ‐interaction

e p

Gd 511 keV 511 keV e+

Acrylic vessels  «hardware» definition of fiducial volume

7m

Muon Inner‐VETO: scintillating oil (78 8”PMTs) Non‐scintillating buffer: same liquid

Isolate PMTs from target

n

Gd

 ~ 8 MeV

Shielding: steel 17 cm: >7

 Improved background reduction

10

PMT support structure: steel tank,

• ptical insulation target/veto area (390 10”

PMTs)

Jelena Maricic, Drexel U

Inner Detector

Inner Detector Lid

Background in Double Chooz

Accidental bkg:

• e+‐like signal: radioactivity from
• e ‐like signal: radioactivity from

materials, PMTs, surrounding rock Rate=Re

• n signal: n from cosmic  spallation
• n signal: n from cosmic  spallation,

thermalized in detector and captured on Gd (Rn)  Accidental coincidence  Accidental coincidence Rate = Re x Rn x Δt Correlated bkg:

• fast n (by cosmic ) recoil on p (low

energy) and captured on Gd

• long‐lived (9Li, 8He) ‐decaying

14

isotopes induced by 

Jelena Maricic, Drexel U

Calibration

CHOOZ had a 1 6% absolute detector systematic uncertainty the best to date Total CHOOZ had a 1.6% absolute detector systematic uncertainty, the best to date. Total uncertainty 2.7% Bugey is the only experiment that has tried to build identical detectors. Result was 2.0% relative error. 5.0% total. D bl Ch l i 0 6% l i i d l h 0 6% l Double Chooz goal is 0.6% relative uncertainty and less than 0.6% total.

Glovebox

Calibration sources:

Glovebox

‐ Natural H n‐capture peak ‐ Radioactive sources

Fish‐line Buffer guide tube

‐ Laser and LED system

Articulated Arm Gamma‐catcher guide tube LED system

Deployed in NT and GC:

137Cs, 60Co, 68Ge, 252Cf

Calibration ‐ 68Ge in the guide tube Calibration Ge in the guide tube

Blue – MC Red ‐ data Example of calibration data:

68Ge in the guide tube.

g Monte Carlo tuning is ongoing.

DC FAR PRELIMINARY PHYSICS DATA DC FAR PRELIMINARY PHYSICS DATA

Data Taking

• Data taking with

far detector started on April 13, 2011

• >100 days

y physics data

• Trigger rate ~120

Hz Hz

• Trigger threshold

< 0.6 MeV h

• 75% physics runs
• 10% calibration

runs

Muons: rate and coincidence Muons: rate and coincidence

• Inner veto 39 Hz
• Inner detector 11 Hz
• Michel electrons from

stopped muons:

• Inner detector 11 Hz

stopped muons:

•  = 2.25  0.13 s

t = time between 2 muons in ms TID – TOD = t = time in s

Muon correlated events Muon correlated events

• H ~ 2.2 MeV
• C ~ 3‐5 MeV

C 3 5 MeV

• Gd ~ 8 MeV
• Energy calibration is
• ngoing
• ngoing

Muon correlated neutron capture on H Muon correlated neutron capture on H

• Muon

correlated neutron capture in Stable for 120 days Rate < 0.1 Hz capture in hydrogen energy window

• 1.9 – 2.5 MeV

Neutrino candidates selection Neutrino candidates selection

1) Apply muon veto cut ~1 ms 1) Apply muon veto cut 1 ms 2) Prompt energy window 0.7 – 12 MeV ‐ singles rate ~10 Hz ‐ singles rate 10 Hz 3) Delayed energy window 6 – 12 MeV i l t ~0 1 H ‐ singles rate ~0.1 Hz 4) Coincidence window ~ 100 s Result: neutrino candidates (neutrinos + bkg)

Time and Space Distribution

• Timing distribution

Timing distribution between prompt and delayed signal in Gd i d (6 12 energy window (6‐12 MeV)   ~ 30 s.

• Spatial distribution

between prompt and d l d i l b delayed signal – between 20‐30 cm is expected.

Energy spectrum in delayed Gd window

• Energy distribution of delayed signals in the Gd energy window

(6‐12 MeV)  peak ~ 8.3 MeV

Position Reconstruction of neutrino d d d l d l candidates – delayed signal vertex

Gd doped Gd doped p target target

Detector top view Detector side view Gamma catcher

Daily Neutrino Rate Daily Neutrino Rate

1 reactor off data ~4000 neutrino candidates in 3 months  already exceeds CHOOZ statistics

Summary and Outlook

• Double Chooz is

detecting neutrinos g

• Backgrounds are low
• We will use Bugey‐4

c‐s for normalization

• Data analysis in

progress progress

• T2K best fit will be

Near detector addresses with this data set