double chooz experiment status...1 g/l gd photons rom ncap ure on dedicated nuclei (gd) t ~ 30 s e ~...
TRANSCRIPT
Double Chooz Experiment StatusDouble Chooz Experiment Status
Jelena Maricic, Drexel University
(for the Double Chooz Collaboration)(for the Double Chooz Collaboration)
S t b 27th SNAC11September, 27th, SNAC11
Double Chooz Collaboration
Outline
• Neutrino detection and 13 measurement
O i f th D bl Ch• Overview of the Double Choozdetector
• 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 s1 6NFiss s1 2 1011P s1 Chooz: P =2x4.25 GWth N~2x1021s‐1 th
Neutrino detection via inverse decay
Target:Distinctive two‐step signature:‐prompt eventPhotons from e+ annihilation
gGd doped scintillator
Photons from e annihilationEe = E+ 0.8 MeV + O(Ee/mn)
‐delayed eventPh t f t
1 g/l GdPhotons 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 Ardennes300 mwe
Hill topology
East ReactorWest Reactor
Started 12/10West Reactor
Physics data taking 04/11
351 m
465 mFrance
115 mweFlat topology
6Jelena Maricic, Drexel U
Start inearly 2013
The ‐ New – Concept – 2 detectorsP(ee) = 1 ‐ sin2(213) sin2(m2
31L/4E)( e e) ( 13) ( 31 / )
Background reductionBackground reduction and calibration arevery important
E = 1‐8 MeVPure e flux
e,,e e,µ,τ
400 mNuclear Power Station Near detector Far detector
1050 m
7Jelena Maricic, Drexel UFar to near detector signal ratio will give information about θ13
Expected Neutrino Oscillation Signal
Two independent sets of information:
sin2(213)=0 04ars
Two independent sets of information:Normalisation + Spectrum distortion
Far/Near ratiosin (213)=0.04sin2(213)=0.1sin2(213)=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(213)=0.12
m2atm= 3.0 10‐3 eV2
Near Detector: ~ 5 105 events/3yReactor 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
l7 m Neutrino target vessel in the center
J. Maricic, Drexel U 9
http://doublechooz.in2p3.fr/
Courtesy of T. Lasserre7 m
The detector designNear 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% GdVolume for ‐interaction (d = 2.3 m, h = 2.8 m)
Extra‐volume for ‐interaction
ep
Gd
511 keV
511 keVe+
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, optical 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 coincidenceRate = 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
CalibrationCHOOZ had a 1 6% absolute detector systematic uncertainty the best to date TotalCHOOZ 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% lDouble 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‐lineBuffer guide tube
‐ Laser and LED system
Articulated ArmGamma‐catcher guide tube
LED systemDeployed in NT and GC: 137Cs, 60Co, 68Ge, 252Cf
Calibration ‐ 68Ge in the guide tubeCalibration Ge in the guide tube
Blue – MCRed ‐ data
Example of calibration data:68Ge in the guide tube.g
Monte Carlo tuning is ongoing.
DC FAR PRELIMINARY PHYSICS DATADC FAR PRELIMINARY PHYSICS DATA
Data Taking• Data taking with
far detector started on April 13, 2011
• >100 days yphysics data
• Trigger rate ~120 HzHz
• Trigger threshold < 0.6 MeV
h• 75% physics runs• 10% calibration
runs
Muons: rate and coincidenceMuons: 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 eventsMuon correlated events
• H ~ 2.2 MeV
• C ~ 3‐5 MeVC 3 5 MeV
• Gd ~ 8 MeV
• Energy calibration is ongoingongoing
Muon correlated neutron capture on HMuon correlated neutron capture on H
• Muoncorrelated neutron capture in
Stable for 120 daysRate < 0.1 Hz
capture in hydrogen energy window
• 1.9 – 2.5 MeV
Neutrino candidates selectionNeutrino candidates selection
1) Apply muon veto cut ~1 ms1) Apply muon veto cut 1 ms2) Prompt energy window 0.7 – 12 MeV‐ singles rate ~10 Hz‐ singles rate 10 Hz
3) Delayed energy window 6 – 12 MeVi 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 distributionTiming distribution between prompt and delayed signal in Gd
i d (6 12energy window (6‐12 MeV) ~ 30 s.
• Spatial distribution between prompt and d l d i l bdelayed 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 lcandidates – delayed signal vertex
Gd doped Gd doped ptarget target
Detector top view Detector side viewGamma catcher
Daily Neutrino RateDaily 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 progressprogress
• T2K best fit will be Near detector
addresses with this data set