Post on 17-Jan-2016
Zakład Spektroskopii Jądrowej
IFD UW
Zenon Janas
Poszukiwanie
podwójnego bezneutrinowego
rozpadu beta w eksperymencie NEMO-3
Warszawa, 04.10.2006
Neutrino mixing
atmospheric angle
reactor angle and CP phase
solar angle
sin212= 0.31±0.03sin223= 0.50±0.06 sin213< 0.012
Maki-Nakagawa-Sakata-Pontecorvo (MNSP) matrix
U =
tritium decay: m < 2.3 eV
Neutrino mass
cosmology: m1+ m2 + m3 < 1.7 eV
oscillation exp.: m22 – m1
2 = 7.9 ± 0.3 10-5 eV2
m32– m1
2 = 2.2 ± 0.4 10-3 eV2
Mass hierarchy
Normal Invertedm2
m1
2
m2
2
m3
2
Degnerate
?
Questions
• absolute mass scale ?
• mass hierarchy ?
• CP symmetry violation ?
• Dirac ( ) or Majorana ( ) particles ?
Double beta decay
decay modes:
2
(A, Z) (A, Z+2) + 2 e + 2 e
(A, Z)
(A, Z+1)
(A, Z+2)
L = 0
Feynman diagram for 2 decay
arb
itra
ry u
nit
s
(Q ~ MeV)
Energy spectra of emitted electrons
22GTM
2decay rate
2221221
GT
v MGT
/
112QG v - phase space factor
- nuclear matrix element
1
2
21
0110
/)()( fi
if
GT MMEM
J. Suhonen et al., Phys. Rep. 300 (1998) 123
Nuclear matrix element in 2
(A, Z)
(A, Z+1)
0+
(A, Z+2)
0+
1+
1+
1+
GT GT
Double beta decay
decay modes:
(A, Z) (A, Z+2) + 2e
2
0
(A, Z) (A, Z+2) + 2 e + 2 e
(A, Z)
(A, Z+1)
(A, Z+2)
L = 0
L = 2
(V+A) current
Light neutrino exchange
Majoron emission
M
Mechanisms of 0 decays
Energy spectra of electrons emitted in decay
M
22
0001021
mMgg
MGT FV
AGT
v
/
0decay rate
1322
31222
2122
1132
sinsincoscos ii ememmm
- effective Majorana mass
00GTF MM ,
52QG v - phase space factor
- nuclear matrix elements
m
Effective mass and neutrino mass scale
degen
erat
e
Normal hierarchy
Inverse hierarchy
- neutrino potential
iArHfM lk
kl
klF ),(, 0iArHfM lk
kl
klklGT ),(, 0
0
2)()sin(
),(A
qrqdq
rR
ArH lk
)( fim MMEA
(A, Z)
(A, Z+1)0+
(A, Z+2)
0+
5+
1+
2-
Nuclear matrix elements in 0
J
V.A. Rodin et al., nucl-th/0503063
Example
QRPA calculations for 100Mo
Nuclear Matrix Elements calculations
Tracking + calorimeter
Both techniques are complementary !!
only total energy measured
high energy resolution
good efficiency
compact detectors ( 10 m)
very pure crystals
source specific
Experimental approaches in decay studies
Calorimeter
HPGe – Te bolometers NEMO
individual electrons observed
modest energy resolution
small efficiency
large detector size ( 50 m)
background measured
universal
H.V. Klapdor-Kleingrothaus et al., Phys. Lett. B586 (2004) 198
02
Heidelberg - Moscow experiment
11 kg 76Ge calorimeter, 71.7 kg·y exposure
)(y../ 3102470 25021 T
eV.. 9010 m
214Bi
Neutrino Ettore Majorana Observatory
NEMO collaboration: 11 countries, 27 laboratories
USAMHCINL
U. Texas
JapanU. Saga
KEKU Osaka
FranceCEN Bordeaux
IReS StrasbourgLAL ORSAY
LPC CaenLSCE Gif/Yvette
UKUC London
U. ManchesterIC London
FinlandU. Jyvaskyla
RussiaJINR DubnaITEP Mosow
Kurchatov Institute
UkraineINR Kiev
ISMA Kharkov
CzechCharles U.
PrahaIEAP Praha
MaroccoFes U.
SlovakiaU. BratislavaSpain
U. ValenciaU. ZarogozaU. Barcelona
3 m
4 m
B (25 G)
20 sectors Location: Fréjus Underground Lab. 4800 m.w.e.
Source: 10 kg of isotopes cylindrical, S = 20 m2, 60 mg/cm2
Tracking detector: 6180 drift wire chamber operating in Geiger mode Gas: He + 4% ethyl alcohol + 1% Ar
Calorimeter: 1940 plastic scintillators low radioactivity PMTs
NEMO-3 detector
© S. Julian, LAL
NEMO-3 sector
R. Arnold et al., NIM A536 (2005) 79
foil
PMT
Scint.
source
Scint.
PMTs
calibration tube
cathodic rings
NEMO-3 sector
100Mo 6.914 kg Q = 3034 keV
82Se 0.932 kg Q = 2995 keV
116Cd 405 g Q= 2805 keV
96Zr 9.4 g Q= 3350 keV
150Nd 37.0 g Q= 3367 keV
Cu 621 g
48Ca 7.0 g Q= 4272 keV
natTe 491 g
130Te 454 g Q= 2529 keV
measurement
background measurement
search
sources in NEMO-3 detector
NEMO-3 detector
water+ B (30 cm)
iron (18 cm)
wood (40 cm)
magnetic coil (25 Gauss)
Shielding of the NEMO detector
Tracking detector:
• vertex resolution:
= 0.6 cm
// = 1.3 cm
• e+/e- separation with a magnetic field of 25 G
~ 3% confusion at 1 MeV
Calorimeter:
• energy resolution:
FWHM (1 MeV) = 14 – 17 %
• time resolution
FWHM (1 MeV) 250 ps
Performance of the NEMO-3
Deposited energy: E1+E2= 2088 keVCommon vertex: (vertex) = 2.1 mm
vertexemission
(vertex)// = 5.7 mm
vertexemission
Transverse view Longitudinal view
Typical 2 event from 100Mo isotope
Trigger: at least 1 PMT > 150 keV
3 Geiger hits (2 neighbour layers + 1)
Trigger rate = 5.8 Hz
events: 1 event every 2.5 minutes
Neutron capture
Electron crossing > 4 MeV
Electron – positron pair
B rejection
Background events in NEMO-3
208Tl 208Pb
electron + 3 ’s
214Bi 214Po 210Pb electron + delay (164 s)
Background events in NEMO-3238U
214Bi(19.9 mn)
210Tl(1.3 mn)
214Po
210Pb22.3 y0.
021%
MeV
(164 s)
Criteria to select events
• 2 tracks with charge < 0
• common vertex
• 2 PMT – associated with tacks
• no other isolated PMT ( rejection )
• TOF condition (external event rejection)
• no delayed track (214Bi rejection)
2 decay of 100Mo
T1/2 = 7.1 ± 0.6 1018 y2
2 sim.bgnd
cos(ee)E1 + E2 (MeV)
219 000 evnts6914 g
389 days
219 000 evnts6914 g
389 days
2 sim.bgnd
Sum Energy Spectrum Angular Distribution
T1/2 > 1.5 1022 y0
2.8 - 3.2 MeV range
Nobserved = 7 events
bgnd = 8.1 ± 1.3
0 decay of 100Mo
R. Arnold et al., PRL 95 (2005) 182302
T1/2 > 4.6 1023 y
m < 0.7 – 2.8 eV
0
02 for T1/2= 51022 y
decay of 82Se (Q=2995 keV)
R. Arnold et al., PRL 95 (2005) 182302
T1/2 > 1 1023 y
m < 1.7 – 4.9 eV
0
02 for T1/2= 51022 y
82Se
T1/2 = 9.6 ± 1.3 1019 y2
2 sim.bgnd
Effective mass and neutrino mass scale
degen
erat
e
Normal hierarchy
Inverse hierarchy
Ge M-HNEMO-3
© S. Julian, LAL
2004 : tent surrounding the detector + air purification system
Radon level 25 mBq/m3 3 mBq/m3
NEMO-3 SuperNEMO
From NEMO-3 to SuperNEMO
7 kg 100 kg Mass of isotope
Efficiency () = 8 % () ~ 30 %
Isotope 100Mo
T1/2() = 7 x 1018 y
82SeT1/2() = 1020 y
~ 1 evt/ 100 kg / y ~ 1 evt / 7 kg / y
T1/2() > 2 x 1024 y
<m> < 0.3 – 1.3 eV
T1/2() > 2 x 1026 y
<m> < 0.04 – 0.1 eV
SENSITIVITYafter 5 years
Resolution~ 11 % at 3 MeV ~ 7 % at 3 MeV
208Tl and 214Bi background
Plane geometry, 20 modules
Top view5 m
1 m
1 module: source: 34 m2 40 mg/m2 of enriched isotope
tracking volume: ~ 3000 drift chamber cells
calorimeter: ~ 1000 scintillators + PMTs
SuperNEMO - preliminary design
© S. Julian, NEMO-3 collaboration
Water shield ( 2 ktons)
Source foil
14 m
Needed cavity:
~60 x 15 x 15 m
Location: Modane, Gran Sasso …?
Full detector ( 2012- )
3,75 m © S. Julian, LAL
20 modules: 100 kg of enriched isotope
Summary
observation of 0 decay Majorana neutrinos
physics beyond SM
complementary experiments needed and
planned
measurement of T1/2(0) nuclear matix element
absolute mass scale
mass hierarchy
Most promissing 0 projects
A.S. Barabash, arXiv:hep-ex/0602037
2005 - 2007 - R&D program
2008 - construction of the SuperNEMO module with 5 kg 82Se
2009 - 2011 - construction and installation of the 20 modules, start taking data with delivered modules
2012 - full SuperNEMO running with 100 kg of 82Se
Plans for SuperNEMO
Simkovic, J. Phys. G, 27, 2233, 2001
Single electron spectrum different between SSD and HSD
22 HSDMonte Carlo HSD
higher levels Background
• Data22 SSD Monte Carlo
Background
• Data
SSDSingle State
HSD: T1/2 = 8.61 0.02 (stat) 0.60 (syst) 1018 y
SSD: T1/2 = 7.72 0.02 (stat) 0.54 (syst) 1018 y
100Mo 22 single energy distribution in favour of Single State Dominant (SSD) decay
4.57 kg.yE1 + E2 > 2 MeV
4.57 kg.yE1 + E2 > 2 MeV
HSD, higher levels contribute to the decay
SSD, 1 level dominates in the decay (Abad et al., 1984, Ann. Fis. A 80, 9)
100Mo
0
100Tc
1
/ndf = 139. / 36 /ndf = 40.7 / 36
NEMO-3 NEMO-3
Esingle (keV) Esingle (keV)
Esingle (keV)
100100Mo 2Mo 222 Single Energy Distribution Single Energy Distribution
•Two tracks of negative charge associated to isolated PM•Energy deposit in each scintillator E > 200 keV. •Event vertex is inside the foil•Distance track-to-vertex: XY < 4 cm, Z<8 cm;•TOF cut: internal hypothesis probality > 4%, external hypothesis probability<1%;
•Reject events with the alpha particle found using alpha_search means:
• if only 1 extra hit in the tracking detector t > 40 sec xy < 4 cm Z < 10 cm
• if at least 2 hits search for a short track t > 2 sec only but all hits on time
•Reject events with two tracks at one side of the foil and a geiger hit in time at the opposite side fo the foil close to the vertex: Möller scattering of decay in gas (Radon).
vertex
Event selection criteriaEvent selection criteria
arb
itra
ry u
nit
s
(Q ~ MeV)
CENBG, IN2P3-CNRS et Université de Bordeaux, France
IReS, IN2P3-CNRS et Université de Strasbourg, France LAL, IN2P3-CNRS et Université Paris-Sud, France LPC, IN2P3-CNRS et Université de Caen, France LSCE, CNRS Gif sur Yvette, France Fes University, Marocco FNSPE, Prague University, Czech Republic INEEL, Idaho Falls, USA ITEP, Moscou, Russia JINR, Dubna, Russia JYVASKYLA University, Finland KURCHATOV Institute, Russia MHC, Massachusets , USA Saga University, Japan UCL London, UK
Neutrino Ettore Majorana Observatory
NEMO collaboration