Äîêóìåíò âçÿò èç êýøà ïîèñêîâîé ìàøèíû. Àäðåñ îðèãèíàëüíîãî äîêóìåíòà : http://nuclphys.sinp.msu.ru/conf/epp10/Kim.pdf Äàòà èçìåíåíèÿ: Sat Sep 7 12:05:49 2013 Äàòà èíäåêñèðîâàíèÿ: Fri Feb 28 02:16:30 2014 Êîäèðîâêà: Ïîèñêîâûå ñëîâà: m 13

Results on 13 Neutrino Oscillations from Reactor Experiments
Soo-Bong Kim (KNRC, Seoul National University) "16th Lomonosov Conference, Moscow, August 22-28, 2013"


Experimental Method of 13 Measurement Experimental Method of 13 Measurement

e e

1.0
e

e

Oscillations observed as a deficit of anti-neutrinos the position of the minimum is defined by m213 (~m223) sin2213



e

e

ProbabilitÈ e

flux before oscillation observed here

2 2 1.27m12 L 1.27m13L 2 2 P e e 1- cos4 13 sin2 212 sin2 - sin 213 sin E E 1200 to 1800 meters Distance

(

)

Find disappearance of e fluxes due to neutrino oscillation as a function of energy using multiple, identical detectors to reduce the systematic errors in 1% level.


Reactor 13 Experiments Reactor 13 Experiments
RENO at Yonggwang, Korea

Daya Bay at Daya Bay, China

Double Chooz at Chooz, France


The RENO Experiment The RENO Experiment
120 m.w.e. Near Detector
0m 29 m 80 13

Far Detector 450 m.w.e.


The Daya Bay Experiment
Measuring neutrino mixing angle 13 6 reactor cores, 17.4 GWth Relative measurement 2 near sites, 1 far site Multiple LS detector modules 20 ton target, 110 ton total weight Good cosmic shielding 250 (860) m.w.e @ near (far) sites

3km tunnel

5


The Double Chooz Experiment
Far Detector L=1050 m Depth = 300 m.w.e. (collecting data since April 2011)

Near Detector L=400 m Depth = 115 m.w.e. (under construction)

Chooz-B Reactors 2â 4.25 GWth

6


13 Reactor Neutrino Detectors 13 Reactor Neutrino Detectors

MO LS Gd-LS H2O


13 Reactor Neutrino Experiments 13 Reactor Neutrino Experiments
Experiments Double Chooz RENO Daya Bay Location Thermal Power (GW) 8.5 16.7 17.4 Flux Weighted Baselines Near/Far (m) [410/1050] 409/1444 470(576)/1648 Depth Near/Far (mwe) 120/300 120/450 250/860 Target Mass (tons) 8.6/8.6 16/16 40â2/80 Flux*Target per year (GWtonyr) 73 [1.0] 267 [3.7] 1392 [19.1]

France Korea China

Daya Bay
Far Double Chooz RENO Daya Bay Apr. 2011 Aug. 2011 Dec. 2011 Near Spring 2014 Aug. 2011 Sep. 2011

Double Chooz

RENO


RENO Status RENO Status
Data taking began on Aug. 1, 2011 with both near and far detectors. (DAQ efficiency : ~95%) A (220 days) : First 13 result [11 Aug, 2011~26 Mar, 2012] PRL 108, 191802 (2012) B (403 days) : Improved 13 result [11 Aug, 2011~13 Oct, 2012] NuTel 2013 C (~700 days) : Shape+rate analysis (in progress) [11 Aug, 2011~31 Jul, 2013] Absolute reactor neutrino flux measurement in progress [reactor anomaly & sterile neutrinos]

Near

A

Far

B C


Daya Bay Operation
A Two Detector Comparison: Sep. 23, 2011 ­ Dec. 23, 2011 Nucl. Inst. and Meth. A 685 (2012), pp. 7897 B 55 days, First Oscillation Result: Dec. 24, 2011 ­ Feb. 17, 2012 Phys. Rev. Lett. 108, 171803 (2012) C Updated analysis: Dec. 24, 2011 ­ May 11, 2012 Chinese Physics C37, 011001 (2013) DAQ eff. ~ 96% Eff. for physics: ~ 94% D Shape+rate analysis, preparation Dec. 24, 2011 ­ Jul. 28, 2012 E 8 AD, double statistics Dec. 24, 2011 ­ Jul. 2013

A

Hall 1

B C

Hall 2

D

Hall 3


Double Chooz Status Double Chooz Status
Far detector alone
Data taking has been in progress since April. 2011 with a far detector alone. New release in 2003 of rate+shape analysis : improved analysis (energy scale, backgrounds) & more statistics 2 channels (neutron capture on Gd and on Hydrogen) with a potential for a combined analysis expect the final sensitivity of 0.03 Fit oscillation through the nuclear power variation : measurement with two reactors, one reactor and zero

Near+Far detectors
A near detector is under construction until spring 2014. The first result of the full experiment will be available in the end of 2014, towards a final sensitivity of 0.01. (10% measurement of 13 )


A Brief History of 13 from Reactor Experiments A Brief History of 13 from Reactor Experiments
Nov. 2011 (Double Chooz ) ) = 0.086±0.051 sin2(2 13 March 2012 (Daya Bay) sin2(213) = 0.092±0.017 April 2012 (RENO) sin2(213) = 0.113±0.023
RENO Mar. 2013 Daya Bay Oct. 2012

(5.2 ) (4.9 )

June 2012 (Double Chooz) sin2(213) = 0.109±0.039 Oct. 2012 (Daya Bay) sin2(213) = 0.089±0.011 March 2013 (RENO) sin2(213) = 0.100±0.018 August 2013 (Daya Bay) sin (213) = 0.090±0.009
2

Double-CHOOZ, arXiv:1207.6632, (2012)

m2

31

= (2.54±0.20)â10-3 eV2


13 from Reactor and Accelerator Experiments 13 from Reactor and Accelerator Experiments
* Reactor
m312 Pee 1 - sin 213 sin 4E
2 2 2 L 4 2 2 m21 - cos 13 sin 212 sin 4E

- Clean measurement of

L

13

with no matter effects

* Accelerator
- mass hierarchy + CP violation + matter effects Precise measurement of
13

Complementary : Combining results from accelerator and reactor based experiments could offer the first glimpse of CP.


Detection of Reactor Antineutrinos Detection of Reactor Antineutrinos
(prompt signal) (delayed ~180 s signal) +p D + (2.2 MeV) ~28 s (0.1% Gd) + Gd Gd + `s (8 MeV)

(0.511MeV)

e e e p n Delayed signal
+

-

Neutrino energy measurement

(0.511MeV)
prompt signal


Gd

30s





E ~8 MeV




Gd Loaded Liquid Scintillator Gd Loaded Liquid Scintillator
Recipe of Liquid Scintillator
Solvent & Flour LAB WLS PPO + Bis-MSB Gd-compound 0.1% Gd + (TMHA)3

Steady properties of Gd-LS
· Stable light yield (~250 pe/MeV) , transparency & Gd concentration (0.11%)

NIM A, 707, 45-53 (2013. 4. 11)


Neutron Capture by Gd Neutron Capture by Gd


Energy Calibration Energy Calibration
Far Detector Near Detector


Energy Calibration Energy Calibration

Cf 252 (2.2/8.0 MeV)

Ge 68 (1,022 keV)

Cf 252 (2.2/7.8 MeV)


Detector Stability of Energy Scale Detector Stability of Energy Scale
IBD candidate's delayed signals (neutron capture by Gd)


IBD Event Signature IBD Event Signature
Prompt signal (e+) : 1 MeV 2's + e+ kinetic energy (E = 1~10 MeV) Delayed signal (n) : 8 MeV 's from neutron's capture by Gd ~26 s (0.1% Gd) in LS
Prompt Signal



Delayed Signal


Backgrounds Backgrounds
Accidental coincidence between prompt and delayed signals Fast neutrons produced by muons, from surrounding rocks and inside detector (n scattering : prompt, n capture : delayed)
9

Li/8He -n followers produced by cosmic muon spallation
Accidentals



Fast neutrons

9Li/8He

-n followers






Gd

n

p
Gd

n

9Li

e

n Gd


9Li/8He 9Li/8He
9

Background Background

Li/8He are unstable isotopes emitting (,n) followers and produced when a muon interacts with carbon in the LS.

9Li/8He

IBD


Background Spectra Background Spectra
Background shapes and rates are well understood Total backgrounds : 6.5% at Far 2.7% at Near


Summary of Final Data Sample Summary of Final Data Sample
(Prompt energy < 10 MeV)

279787 20.48± 2.13 737.69± 2.58 369.03 62.0± 0.014 3.61± 0.05 13.73± 2.13 3.14± 0.09

30211 4.89± 0.60 70.13± 0.75 402.69 71.4± 0.014 0.60± 0.03 3.61± 0.60 0.68± 0.04


Measured Spectra of IBD Prompt Signal Measured Spectra of IBD Prompt Signal

Live time : 402.7 days No. of IBD : 30,211 No. of bkg. : 1,970 (6.5%)

Live time : 369.0 days No. of IBD : 279,787 No. of bkg. : 7,558 (2.7%)


IBD Prompt Signal (Data vs. MC) IBD Prompt Signal (Data vs. MC)

???


Expected Reactor Antiineutrino Fluxes Expected Reactor Ant neutrino Fluxes
Reactor neutrino flux

( E ) =

Pth
isotopes

isotopes


i

f i Ei


i

f i i ( E )

- Pth : Reactor thermal power provided by the YG nuclear power plant - fi : Fission fraction of each isotope determined by reactor core simulation of Westinghouse ANC - i(E) : Neutrino spectrum of each fission isotope [* P. Huber, Phys. Rev. C84, 024617 (2011) T. Mueller et al., Phys. Rev. C83, 054615 (2011)] - Ei : Energy released per fission [* V. Kopeikin et al., Phys. Atom. Nucl. 67, 1982 (2004)]


Observed Daily Averaged IBD Rate Observed Daily Averaged IBD Rate
A new way to measure the reactor thermal power remotely!!!

R2

R1

R5

R4

R6

R5

R3

R3+R5+R6


Reactor Antiineutrino Disappearance Reactor Ant neutrino Disappearance

R=

Far observed Far exp ected

= 0.929 ± 0.006( stat ) ± 0.009( syst )

Reduced 2 = 1.21

A clear deficit in rate (7.1% reduction) Consistent with neutrino oscillation in the spectral distortion


Reactor Antineutrino Oscillations Reactor Antineutrino Oscillations


RENO's Projected Sensitivity of 13 RENO's Projected Sensitivity of 13

sin 213 = 0.100 ± 0.010( stat.) ± 0.015( syst.)
2

(402 days)

0.100 ± 0.018 (5.6

) (18 % precision)

± 0 .007 (~ 13 )
(7 % precision)

(5 years)

2013. 3

5 years of data : ±0.007 (7% precision)
- statistical error : ±0.010 ±0.005 - systematic error : ±0.015 ±0.005
(7 % precision)


Daya Bay Projected Senstivity
8 AD run Current data

Released: 12.5% precision
sin2213 = 0.089±0.011

Projected: 4% At least 5 years' operation

Physics: 1.measure sin2213 to 4% precision 2.Precise reactor spectrum 3.Direct measurement of m231 4.Cosmogenic neutrons, isotopes 5.Exotic searches
32


Near Detector

Far Detector

RENO-50
18 kton LS Detector ~47 km from YG reactors Mt. Guemseong (450 m) ~900 m.w.e. overburden


Summary Summary
A clear disappearance of reactor antineutrinos is observed. The smallest mixing angle 13 that was the most elusive puzzle of neutrino oscillations, is firmly measured by the reactor experiments.

sin 2 213 = 0 .100 ± 0 .010 ( stat ) ± 0 .015 ( syst )
sin 089 ± 0 010 ( stat ± 0 sin 2 213 = 0 .2 213 = .0 .090 ± 0).009.005 ( syst ) sin 2 213 = 0 .109 ± 0 .030 ( stat ) ± 0 .025 ( syst )

(RENO ) (Daya Bay) (Double Chooz)

A surprisingly large value of 13 will strongly promote the next round of neutrino experiments to find the CP phase and determine the mass hierarchy. Precise measurement of 13 by the reactor experiments [Daya Bay: 4%, RENO: 7%, Double Chooz: 10% from 5 years of data] will provide the first glimpse of CP. if accelerator results are combined.