Prezentace se nahrává, počkejte prosím

Prezentace se nahrává, počkejte prosím

Hmotná neutrina Vít Vorobel, ÚČJF MFF UK Úvod (milníky, pojmy) –Kinematická měření m –Oscilace neutrin (mixování neutrin) –Dvojný beta-rozpad (Majorana.

Podobné prezentace


Prezentace na téma: "Hmotná neutrina Vít Vorobel, ÚČJF MFF UK Úvod (milníky, pojmy) –Kinematická měření m –Oscilace neutrin (mixování neutrin) –Dvojný beta-rozpad (Majorana."— Transkript prezentace:

1 Hmotná neutrina Vít Vorobel, ÚČJF MFF UK Úvod (milníky, pojmy) –Kinematická měření m –Oscilace neutrin (mixování neutrin) –Dvojný beta-rozpad (Majorana x Dirac ?) Experiment NEMO-3 – dvojný beta-rozpad Experiment SuperNEMO Experiment Daya Bay – oscilace reaktorových antineutrin Seminář ÚČJF - Vít Vorobel

2 Neutrinové milníky 1930 Pauli – neutrální částice v  -rozpadu 1937 Majorana – co když  anti- 1956 Reines, Cowan – pozorování reaktorových anti Pontecorvo – hypotéza oscilací neutrin 1968 Davis – pozorování slunečních  (deficit)  množství experimentů a trpělivost 1998 Super-Kamiokande – pozorování oscilací atmosférických  80 let poté 2010 Hierarchie? Majorana? Hmotnost? Proč tak malá? Seminář ÚČJF - Vít Vorobel

3 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) Seminář ÚČJF - Vít Vorobel3

4 Kinematická měření. Beta – rozpad 3 H –Mainz, Troick, m e < 2 eV/c 2 –KATRINE, plánovaná citlivost 0.2 eV/c 2 Rozpad  – PSI, m < 170 keV/c 2 Rozpad  – OPAL, DELPHI,ALEPH m < 18 MeV/c Seminář ÚČJF - Vít Vorobel4

5 Oscilace neutrin. Oscilace ve vakuu - Pontecorvo Seminář ÚČJF - Vít Vorobel5 Oscilace v hmotném prostředí - Wolfenstein 1978, Mikheyev-Smirnov 1985 (MSW effect) –významný efekt pro sluneční a urychlovačová neutrina –Z 0 : e     –W + : pouze e –Efektivní m i jsou jiná v prostředí než ve vakuu 2 neutrina: oscilační délka

6  -rozpad Seminář ÚČJF - Vít Vorobel6 (A,Z)  (A,Z+2) + 2e (A,Z)  (A,Z+2) + 2e -  2 : proces dovolený v SM, T 1/2 ~ y  0 : proces mimo SM, T 1/2  y

7 NEMO-3/SuperNEMO collaboration Neutrino Ettore Majorana Observatory (Neutrino Experiment on MOlybdenum – historical name) 80 physicists / 30 institutions Seminář ÚČJF - Vít Vorobel

8  and neutrino fundamental properties Probe of neutrino nature. Neutrinos are Majorana fermions (particle  antiparticle) if  0 takes place  See-Saw mechanism, Leptogenesis, Baryon asymmetry, CP violation Neutrino mass hierarchy.  0 measurements might help to establish the right one. Absolute mass scale.  0 experiments are among the most sensitive ones. Spreads are due to variations of unknown CP phases Seminář ÚČJF - Vít Vorobel

9 3 m 4 m B (25 G) Source : 10 kg of  isotopes cylindrical, S = 20 m 2, 60 mg/cm 2 Tracking detector : drift wire chamber operating in Geiger mode (6180 cells) Gas: He + 4% ethyl alcohol + 1% Ar + 0.1% H 2 O Calorimeter : 1940 plastic scintillators coupled to low radioactivity PMTs The NEMO3 detector Fréjus Underground Laboratory : 4800 m.w.e. Magnetic field: 25 Gauss Gamma shield: Pure Iron (18 cm) Neutron shield: borated water (~30 cm) + Wood (Top/Bottom/Gaps between water tanks) Able to identify e , e ,  and  delayed 20 sectors Seminář ÚČJF - Vít Vorobel

10 NEMO3 unique features Multi-source detector Measurement of full  -event pattern Self-determination of ALL background components measuring independent channels Multisource  -detector Seminář ÚČJF - Vít Vorobel

11 Unique spectra from tracko-calo technique 100 Mo  2 Results NEMO-3 ’’  -factory’’ in action Sum energy spectrumAngular distributionSingle electron energy spectrum Data - MC ββ2 - background subtracted 100 Mo Latest results: events 389 days S/B= Mo Seminář ÚČJF - Vít Vorobel

12 100 Mo  2 Results Summary of NEMO-3  -results Isotope Expo- sure, days EventsS/B T 1/2 (2νββ), years Published 100 Mo (7.11 ± 0.02(stat)±0.54(syst))·10 18 (SSD favored) 100 Mo(0 + 1 ) ,54 ( (stat) )±0.8(syst))· Se (9.6± 0.3(stat)±1.0(syst))· Cd (2.8± 0.1(stat)±0.3(syst))· Nd ( (stat)±0.63(syst))·10 18 New preliminary 130 Te (6.9± 0.9(stat)±1.0(syst))· Zr (2.35± 0.14(stat)±0.16(syst))· Ca ( (stat)±0.4(syst))·10 19 Systematic studies of  process provide crucial knowledge for  search! 12

13 100 Mo  2 Results  -results Isotope T 1/2 (0νββ) limit, ×10 24 years, eVExperimentYear 76 Ge > 15.7< IGEX Ge HM(KGC) Ge > 15.5< HM(Others) Te >3< CUORICINO Mo >1.1< NEMO-32009

14 From NEMO to SuperNEMO SUPERNEMO R&D is in progress since 2006 NEMO-3  SuperNEMO 100 Mo, 7kg Isotope, mass 82 Se, kg 208 Tl: < 20  Bq/kg 214 Bi: < 300  Bq/kg Background in  -foil 208 Tl: < 2  Bq/kg 214 Bi: < 10  Bq/kg 8% Efficiency 30% 3 MeV Energy resolution (FWHM) 3 MeV T 1/2 > 2 x y < 0.3 – 0.8 eV Sensitivity T 1/2 > 1-2 x y < 40 – 100 meV NEMO-3 successful experience allows to extrapolate tracko-calo technique on larger mass next generation detector to reach new sensitivity level.

15 20 modules, each of them hosts: - 5 kg of source foil ( 82 Se, 40mg/cm 2 ) Geiger channels 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

16 SuperNEMO demonstrator SuperNEMO demonstrator (first module) being finalizing, which will: 1)Prove the concept 2)Test  at level of KGC 3)Start in 2012 Calorimeter R&D Tracker R&D Low background R&D Simulations Source: 6.3 kg of 82 Se BiPo setup

17 BiPo setup Seminář ÚČJF - Vít Vorobel 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 150 Nd (excitovaný stav) SuperNEMO Studie alternativní podoby kalorimetru (PD x PMT) Optimalizace tvaru scintilátorů Měření Rn Testování scintilátorů

18

19 NEMO3/SuperNEMO collaboration meeting, Prague mm Scintillator response vs irradiation position Scintillator position scan Irradiated area   11.6 mm 1 MeV, % Peak position, ADC

20 20 Daya Bay Reactor Antineutrino Oscillation Experiment Seminář ÚČJF - Vít Vorobel

21 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, Dongguan Polytech. 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 Seminář ÚČJF - Vít Vorobel

22 22 ?  13  The Last Unknown Neutrino Mixing Angle  23    45  U MNSP Matrix Maki, Nakagawa, Sakata, Pontecorvo What is  e fraction of 3 ? U e3 is the gateway to CP violation in neutrino sector: ? atmospheric, accelerator reactor, accelerator 0  SNO, solar SK, KamLAND  12 ~ 32°  23 = ~ 45°  13 = ? P(   e ) - P(   e )  sin(2  12 )sin(2  23 )cos 2 (  13 )sin(2  13 )sin  ˉˉ Seminář ÚČJF - Vít Vorobel

23 23 Measuring  13 Using Reactor Anti-neutrinos Electron anti-neutrino disappearance probability Sin 2   = 0.1  m 2 31 = 2.5 x eV 2 Sin 2   =  m 2 21 = 8.2 x eV 2 Small oscillation due to  13 < 2 km Large oscillation due to  12 > 50 km e disappearance at short baseline(~2 km): unambiguous measurement of  13 Osc. prob. (integrated over E  ) vs distance Seminář ÚČJF - Vít Vorobel

24 24 Total length: ~3100 m Daya Bay NPP, 2  2.9 GW Ling Ao NPP, 2  2.9 GW Ling Ao-ll NPP (under construction) 2  2.9 GW in m 810 m 465 m 900 m Daya Bay Near site 363 m from Daya Bay Overburden: 98 m Ling Ao Near site ~500 m from Ling Ao Overburden: 112 m Far site 1615 m from Ling Ao 1985 m from Daya Overburden: 350 m entrance Filling hall Mid site 873 m from Ling Ao 1156 m from Daya Overburden: 208 m Construction tunnel 4 x 20 tons target mass at far site Daya Bay: Powerful reactor close to mountains Seminář ÚČJF - Vít Vorobel

25 25 Detection of  e Time, space and energy-tagged signal  suppress background events. E   T e+ + T n + (m n - m p ) + m e+  T e MeV Inverse  -decay in Gd-doped liquid scintillator: 0.3b  + Gd  Gd*  Gd +  ’s (8 MeV) ( t ~30μs)  + p  D +  (2.2 MeV) ( t ~180μs) 50,000b Seminář ÚČJF - Vít Vorobel

26 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 ton II.  -catcher: liquid scintillator, 42.5 cm thick III. Buffer shielding: mineral oil, 48.8 cm thick 12.2% 13cm With 192 PMT’s on circumference and reflective reflectors on top and bottom: Seminář ÚČJF - Vít Vorobel

27 27 Inverse-beta Signals Antineutrino Interaction Rate (events/day per 20 ton module) Daya Bay near site 840 Ling Ao near site740 Far site 90 Delayed Energy Signal Prompt Energy Signal MC statistics corresponds to a data taking with a single module at far site in 3 years. E e+ (“prompt”)  [1,8] MeV E n-cap (“delayed”)  [6,10] MeV t delayed -t prompt  [0.3,200]  s 1 MeV8 MeV 6 MeV10 MeV Seminář ÚČJF - Vít Vorobel

28 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 Seminář ÚČJF - Vít Vorobel

29 29 Backgrounds DYB siteLA siteFar site Fast n / signal 0.1% 9 Li- 8 He / signal 0.3%0.2% Accidental/signal <0.2% <0.1% Background = “prompt”+”delayed” signals that fake inverse-beta events Three main contributors, all can be measured: Background typeExperimental Handle Muon-induced fast neutrons (prompt recoil, delayed capture) from water or rock >99.5% parent “water” muons tagged ~1/3 parent “rock” muons tagged 9 Li/ 8 He (T 1/2 = 178 msec,  decay w/neutron emission, delayed capture) Tag parent “showing” muons Accidental prompt and delay coincidencesSingle rates accurately measured Background/Signal: Seminář ÚČJF - Vít Vorobel

30 30 Daya Bay: Status and Plan Ground Breaking Oct 07 CD-3 reviewcomleted 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 Run Time (Years) sin 2 2  Goal: sin 2 2  13 (90% C.L.) Seminář ÚČJF - Vít Vorobel

31 31 Testování RPC kosmickým zářením – IHEP Peking Seminář ÚČJF - Vít Vorobel Kritéria testů: účinnost >95% singles (šum)< 0.8Hz/cm 2 dark current< 10 μA/m 2 Testováno 1600 ks RPC, odmítnuto 15%

32 谢谢你们 ! Děkuji za pozornost ! Seminář ÚČJF - Vít Vorobel32


Stáhnout ppt "Hmotná neutrina Vít Vorobel, ÚČJF MFF UK Úvod (milníky, pojmy) –Kinematická měření m –Oscilace neutrin (mixování neutrin) –Dvojný beta-rozpad (Majorana."

Podobné prezentace


Reklamy Google