neurychlovačová fyzika elementárních částicvorobel/100324seminaripnp/... · 2018-09-21 ·...

Hmotná neutrinaVít Vorobel, ÚČJF MFF UK

• Úvod (milníky, pojmy)– Kinematická měření mν

– Oscilace neutrin (mixování neutrin)– Dvojný beta-rozpad (Majorana x Dirac ?)

• Experiment NEMO-3 – dvojný beta-rozpad• Experiment SuperNEMO• Experiment Daya Bay – oscilace reaktorových antineutrin

24.03.2010 1Seminář ÚČJF - Vít Vorobel

Neutrinové milníky• 1930 Pauli – neutrální částice v β-rozpadu• 1937 Majorana – co když ν = anti-ν ?• 1956 Reines, Cowan – pozorování reaktorových anti-ν• 1957 Pontecorvo – hypotéza oscilací neutrin• 1968 Davis – pozorování slunečních ν (deficit)

� množství experimentů a trpělivost

• 1998 Super-Kamiokande – pozorování oscilací atmosférických ν

• .................................................................................

� 80 let poté• 2010 Hierarchie? Majorana? Hmotnost? Proč tak malá? ...


∑∑ ==i

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αα*

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cos0sin010

sin0cos

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1212

1212

1313

1313

2323

23232

1

α

α

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θθ

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Základní formalizmus - mísení neutrin

• Slabé stavy• Hmotnostní stavy• Směšovací matice Pontecorvo-Maki-Nakagawa-Sakata

• Informace o hmotnosti neutrin (9 parametrů)– Hmotnosti (3)– Parametry PMNS matice

• Směšovací úhly (3)• Diracova fáze (1)• Majoranovy fáze (2)

24.03.2010 Seminář ÚČJF - Vít Vorobel 3

3,2,1,

,,

=

=

im

e

iiν

τµανα

21

132312

321

ααδ

θθθ

mmm

22222 2 µµπµπνµ µνµπ mpmmmm +−+=+→ ++

( ) ±± +→+→ πντππντ ττ 35 0

Kinematická měření .• Beta – rozpad 3H

– Mainz, Troick, mνe < 2 eV/c2

– KATRINE, plánovaná citlivost 0.2 eV/c2

• Rozpad π – PSI, mνµ < 170 keV/c2

• Rozpad τ – OPAL, DELPHI,ALEPH• mντ < 18 MeV/c2


( ) ( ) ( ) ( ) 22,e

mEQEQpEZEFEN ν−−⋅−⋅∝

222i

ii mUm ∑= ανα

EcmEcmEpcctxcmE i

ii 2

424222 −≈−=≈>>

( ) ββ

βααα ννν ∑ ∑∑

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−≈

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iii

i

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jijjii

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4sinRe4

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322**2

βαβαβαβααβαββα δνννν

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2i

iiiiiiii x

EcmipxtEicmi νννττν

−≈

−−=

−=

222jiij mmm −=∆

( ) ( )( )2232

22 48.24sin2sineVm

MeVEmcm

ELLxP

∆∗=

∆==→

ππθνν βα

Oscilace neutrin .• Oscilace ve vakuu - Pontecorvo 1957


• Oscilace v hmotném prostředí - Wolfenstein 1978, Mikheyev-Smirnov 1985 (MSW effect)– významný efekt pro sluneční a urychlovačová neutrina– Z0 : νe, νµ, ντ

– W+: pouze νe

– Efektivní mi jsou jiná v prostředí než ve vakuu

ijjiij mmm θ2sin2222 −=∆

2 neutrina: oscilační délka

ββ-rozpad


∑=i

ieie mUm 2ν

(A,Z)→(A,Z+2) + 2e- + 2ν (A,Z)→(A,Z+2) + 2e-

ββ2ν: proces dovolený v SM, T1/2 ~ 1020y ββ0ν: proces mimo SM, T1/2 ≥ 1025y

22

0002/1

),(1evv mMZQG

T ννββ ××=

NEMO-3/SuperNEMO collaborationNeutrino Ettore Majorana Observatory

(Neutrino Experiment on MOlybdenum – historical name)80 physicists / 30 institutions


0νββ and neutrino fundamental properties

Probe of neutrino nature.Neutrinos are Majorana fermions (particle ≡antiparticle) if ββ0ν takes place ⇒ See-Saw mechanism, Leptogenesis, Baryon asymmetry, CP violation

Neutrino mass hierarchy. ββ0ν measurements might help to establish the right one.

Absolute mass scale.ββ0ν experiments are among the most sensitive ones.

Spreads are due to variations of unknown CP phases


3 m

B (25 G)

Source: 10 kg of ββ isotopescylindrical, S = 20 m2, 60 mg/cm2

Tracking detector:drift wire chamber operating

in Geiger mode (6180 cells)Gas: He + 4% ethyl alcohol + 1% Ar + 0.1% H2O

Calorimeter:1940 plastic scintillatorscoupled to low radioactivity PMTs

The NEMO3 detectorFréjus Underground Laboratory : 4800 m.w.e.

Magnetic field: 25 GaussGamma shield: Pure Iron (18 cm)Neutron shield: borated water (~30 cm) + Wood (Top/Bottom/Gaps between water tanks)

Able to identify e−, e+, γ and α−delayed

20 sectors


NEMO3 unique features

Multi-source detector Measurement of full ββ-event pattern

Self-determination of ALL background components measuring independent channels

Multisource ββ-detector


Unique spectra from tracko-calo technique

100Mo ββ2ν ResultsNEMO-3 ’’2νββ-factory’’ in action

Sum energy spectrum Angular distributionSingle electron energy spectrum

• Data- MC ββ2ν- background

subtracted

100Mo

Latest results:

219 000 events389 daysS/B=40

100Mo 100Mo


100Mo ββ2ν ResultsSummary of NEMO-3 2νββ-results

IsotopeExpo-sure, days

Events S/B T1/2(2νββ), years

Published

100Mo 389 219000 40 (7.11 ± 0.02(stat)±0.54(syst))·1018 (SSD favored)

100Mo(0+1) 334.3 37,5 4 (5.7+1.3

-0.9(stat) )±0.8(syst))·1020

82Se 389 2750 4 (9.6± 0.3(stat)±1.0(syst))·1019

116Cd 168.4 1371 7.5 (2.8± 0.1(stat)±0.3(syst))·1019

150Nd 939 2018 2.8 (9.11+0.25-0.22(stat)±0.63(syst))·1018

New preliminary

130Te 1152 236 0.35 (6.9± 0.9(stat)±1.0(syst))·1020

96Zr 1221 428 1 (2.35± 0.14(stat)±0.16(syst))·1019

48Ca 943.2 116 6.8 (4.4+0.5-0.4(stat)±0.4(syst))·1019

Systematic studies of 2νββ process provide crucial knowledge for 0νββ search! 12

100Mo ββ2ν Results0νββ-results

Isotope T1/2(0νββ) limit, ×1024years <mν>, eV Experiment Year

76Ge > 15.7 <0.3-1.35 IGEX 200276Ge 15. 0.17-0.45 HM(KGC) 200476Ge > 15.5 <0.3-1.35 HM(Others) 2005130Te >3 <0.2-0.7 CUORICINO 2008

100Mo >1.1 <0.45-0.93 NEMO-3 2009

From NEMO to SuperNEMO

SUPERNEMO R&D is in progress since 2006

NEMO-3 ⇒ SuperNEMO100Mo, 7kg Isotope, mass 82Se,100-200 kg

208Tl: < 20 µBq/kg214Bi: < 300 µBq/kg

Backgroundin ββ-foil

208Tl: < 2 µBq/kg214Bi: < 10 µBq/kg

8% Efficiency 30%

8% @ 3 MeV Energy resolution (FWHM) 4% @ 3 MeV

T1/2 > 2 x 1024 y<mν> < 0.3 – 0.8 eV Sensitivity T1/2 > 1-2 x 1026 y

<mν> < 40 – 100 meV

ENtM

WayT

BGR ∆××

×∝εν )(0

2/1

NEMO-3 successful experience allows to extrapolate tracko-calo technique on larger mass next generation detector to reach new sensitivity level.

20 modules, each of them hosts:

- 5 kg of source foil (82Se, 40mg/cm2)

- 2000-3000 Geiger channels

- 600 Calorimeter channels:

PVT Scintillator + 8’’ PMT

SuperNEMO basic design

SuperNEMO module

SuperNEMO is the favorite project to be hosted in the new LSM laboratory (hall A) planned to be opened at 2013

SuperNEMO demonstrator

SuperNEMO demonstrator (first module) being finalizing, which will: 1) Prove the concept2) Test 0νββ at level of KGC3) Start in 2012

Calorimeter R&D Tracker R&D

Low background R&DSimulations

Source: 6.3 kg of 82Se

BiPo setup

24.03.2010 16

BiPo setup


Aktivity MFF UK v NEMO-3/SuperNEMO• V úzké spolupráci s UTEF ČVUT

• NEMO-3• Simulace a návrh neutronového stínění• Koordinace výroby/dodávky nosné konstrukce detektoru (Transporta Chrudim)• Koordinace výroby/dodávky „Radon Trapping Facility“ (Hradec Králové)• Analýza dat 150Nd (excitovaný stav)

• SuperNEMO• Studie alternativní podoby kalorimetru (PD x PMT)• Optimalizace tvaru scintilátorů• Měření Rn• Testování scintilátorů

27.01.2009 NEMO3/SuperNEMO collaboration meeting, Prague

1911.9 12.5 13.7

13.9

14.113.811.8

12.7 11.5

20 mm20 mm

Scintillator response vs irradiation position

91.5 88.6 85.5

87.3

89.9

91.988.7

90.6 92.5

Scintillatorposition scan Irradiated area 11.6 mm

FWHM @ 1 MeV, %

Peak position, ADC

20

Daya Bay Reactor Antineutrino Oscillation Experiment

24.03.2010 Seminář ÚČJF - Vít Vorobel

21

The Daya Bay Collaboration

North America (14)(54)BNL, Caltech, George Mason Univ., LBNL,

Iowa state Univ. Illinois Inst. Tech., Princeton,RPI, UC-Berkeley, UCLA, Univ. of Houston,

Univ. of Wisconsin, Virginia Tech., Univ. of Illinois-Urbana-Champaign

Asia (18) (88)IHEP, Beijing Normal Univ., Chengdu Univ. of Sci. and Tech., CGNPG, CIAE, DongguanPolytech. Univ., Nanjing Univ.,Nankai Univ.,

Shandong Univ., Shenzhen Univ., Tsinghua Univ., USTC,

Zhongshan Univ., Hong Kong Univ.,Chinese Hong Kong Univ., National Taiwan Univ.,

National Chiao Tung Univ., National United Univ.

Europe (3) (9)JINR, Dubna, Russia

Kurchatov Institute, Russia

Charles University, Czech Republic

~ 150 collaborators


22

?

θ13: The Last Unknown Neutrino Mixing Angle

θ23 ≈ 45°

UMNSP MatrixMaki, Nakagawa, Sakata, Pontecorvo

=1 0 00 cosθ23 sinθ23

0 −sinθ23 cosθ23

×cosθ13 0 e− iδ CP sinθ13

0 1 0−eiδCP sinθ13 0 cosθ13

×cosθ12 sinθ12 0−sinθ12 cosθ12 0

0 0 1

×1 0 00 eiα / 2 00 0 eiα / 2+ iβ

• What is νe fraction of ν3?• Ue3 is the gateway to CP violation in neutrino

sector:

U =Ue1 Ue2 Ue 3

Uµ1 Uµ2 U µ 3

Uτ1 Uτ 2 Uτ 3

=0.8 0.5 Ue 3

−0.4 0.6 0.70.4 −0.6 0.7

?

atmospheric,accelerator

reactor,accelerator

0νββSNO, solar SK,KamLANDθ12 ~ 32°θ23 = ~ 45° θ13 = ?

P(νµ → νe) - P(νµ → νe) ∝sin(2θ12)sin(2θ23)cos2(θ13)sin(2θ13)sinδˉˉ


23

∆⋅⋅+

∆⋅≈

ννθθθ

ELm

ELmPdis 4

sin2sincos4

sin2sin2212

122

134

2132

132

Measuring θ13 Using Reactor Anti-neutrinos

Electron anti-neutrino disappearance probability

Sin22θ13 = 0.1∆m2

31 = 2.5 x 10-3

eV2

Sin22θ12 = 0.825∆m2

21 = 8.2 x 10-5

eV2

Small oscillation due to θ13< 2 km

Large oscillation due to θ12> 50 km

νe disappearance at short baseline(~2 km): unambiguous measurement of θ13

Osc. prob. (integrated over Eν ) vs distance


24Total length: ~3100 mDaya Bay

NPP, 2×2.9 GW

Ling AoNPP, 2×2.9 GW

Ling Ao-ll NPP(under construction) 2×2.9 GW in 2011

Daya Bay Near site363 m from Daya BayOverburden: 98 m

Ling Ao Near site~500 m from Ling AoOverburden: 112 m

Far site1615 m from Ling Ao1985 m from DayaOverburden: 350 m

entranceFilling hall

Mid site873 m from Ling Ao1156 m from DayaOverburden: 208 m

Constructiontunnel

4 x 20 tons target mass at far site

Daya Bay: Powerful reactor close to mountains


25

Detection of νe

Time, space and energy-tagged signal⇒ suppress background events.

Eν ≈ Te+ + Tn + (mn - mp) + m e+ ≈ Te+ + 1.8 MeV

Inverse β-decay in Gd-doped liquid scintillator:

0.3b→ + Gd → Gd*→ Gd + γ’s(8 MeV) (t~30μs)→ + p → D + γ(2.2 MeV) (t~180μs)

50,000b

nepe +→+ +ν


26

Antineutrino Detector

Cylindrical 3-Zone Structure separated by acrylic vessels:

I. Target: 0.1% Gd-loaded liquid scintillator, diameter=height= 3.1 m, 20 tonII. γ-catcher: liquid scintillator, 42.5 cm thickIII. Buffer shielding: mineral oil, 48.8 cmthick

vertex14%~ , 14cm(MeV)

=E Eσ σ

12.2%13cm

With 192 PMT’s on circumference and reflective reflectors on top and bottom:


27

Inverse-beta SignalsAntineutrino Interaction Rate(events/day per 20 ton module)Daya Bay near site 840 Ling Ao near site 740 Far site 90

Delayed Energy SignalPrompt Energy Signal

MC statistics corresponds to a data taking with a single module at far site in 3 years.

Ee+(“prompt”) ∈[1,8] MeVEn-cap (“delayed”) ∈ [6,10] MeV

tdelayed-tprompt ∈ [0.3,200] µs

1 MeV 8 MeV6 MeV 10 MeV


28

Muon “Veto” System

Surround detectors with at least 2.5m of water, which shields the external radioactivity and cosmogenic background

Water shield is divided into two optically separated regions (with reflective divider, 8” PMTs mounted at the zone boundaries), which serves as two active and independent muon tagger

Augmented with a top muon tracker: RPCs

Combined efficiency of tracker > 99.5% with error measured to better than 0.25%

Resistive plate chamber (RPC)

Inner water shieldOuter water shield


29

Backgrounds

DYB site LA site Far siteFast n / signal 0.1% 0.1% 0.1%

9Li-8He / signal 0.3% 0.2% 0.2%Accidental/signal <0.2% <0.2% <0.1%

Background = “prompt”+”delayed” signals that fake inverse-beta events

Three main contributors, all can be measured:

Background type Experimental HandleMuon-induced fast neutrons (prompt recoil, delayed capture) from water or rock

>99.5% parent “water” muons tagged~1/3 parent “rock” muons tagged

9Li/8He (T1/2= 178 msec, β decay w/neutron emission, delayed capture)

Tag parent “showing” muons

Accidental prompt and delay coincidences Single rates accurately measured

Background/Signal:


30

Daya Bay: Status and Plan• Ground Breaking Oct 07• CD-3 review comleted Spring 08• Surface Assembly Building occupancy March 09• Mini Dry Run Dec 09• Dry Run Spring 09• Daya Bay Near Hall ready for data taking 2010• All near and far halls ready for data taking 2011

0 1 2 3 4 5

0.01

0.02

0.03

0.04

Run Time (Years)

Sens

itivi

ty

Run Time (Years)

sin2 2

θ 13

0.01Goal:si

n2 2θ 1

3(9

0% C

.L.)


31

Testování RPC kosmickým zářením – IHEP Peking


Kritéria testů:účinnost >95% singles (šum)< 0.8Hz/cm2 dark current< 10 μA/m2

Testováno 1600 ks RPC, odmítnuto 15%

谢谢你们！Děkuji za pozornost !


neurychlovačová fyzika elementárních částicvorobel/100324seminaripnp/... · 2018-09-21 ·...

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