Neutrino Masses

flavors N

h.cmmm ,...,,',.'''''' ellL RlclL

RllLl

clR

LllRllL

Dll

L2

A,Z A,Z + 2 e e

double beta decay

l lii

iU

oscillations

Majorana L0 Dirac

1) Oscillations:

2) Kinematics in weak decays:

3) 0 double beta decay:

222

2*

',

*'' 2

exp

kiik

iklkklli

kiilll

mmmE

xmiUUUUP

iik mU ,

Majorana

Dirac

iei

N

iei

iLei

N

i

Lei mUU

mUUm

1

2

1

0

Mainzfrozen T2 source, E=4.8 eV

Troitskgaseous T2 source, E=3.5 eV

Reported anomaly most likely experimentalartifact

CL) % (95eV 2.2 m

eV2.12.21.2 m

2

CL) % (95eV 2.2 m

eV2.02.52.3 m

2

Katrin(Karlsruhe)

eV 0.35 y sensitiviteVE 1

187Re 187Os + e- + e E0=2.5 keV, 43 Gyr, abundance 62.8 %

Milano: 10 AgReO4 crystals (250-300 g each)

as cryogenic bolometers (T=10 mK)

E(FWHM)=28 eV at 2.5 keV

m< 21.7 eV at 90 % CL

Double Beta Decay

-

-

1 2 2) : ( , ) ( , ) A Z A Z e e ec

ec

T G E Z MGT1 22 1 2

02 2

/ ,

2

20

2

20

00

102/1

,

mMg

gMZEG

T

FA

VGT

d(n) u(p)

ece

e

W

W

d(n) u(p)

ce

L0

2 0 2) : ( , ) ( , ) A Z A Z e e

e-c

eRW

d(n)

d(n)

u(p)

u(p)

W e-eL

m

N

i

Lej

Lejj UUmm

2

1

L 2

Eee

dN dt

E0

(A,Z)

0+ (A,Z+1)

(A,Z+2)

2+

0+

E0e-e-

Popular candidates

E0 (MeV) Abundance (%)

0.187 4.27148Ca 48Ca76Ge 76Ge 2.040 7.8 82Se 82Kr 2.995 9.2

100Mo 100Ru 3.034 9.6128Te 128Xe 0.868 31.4130Te 130Xe 2.533 34.5136Xe 136Ba 2.479 8.9150Nd 150Sm 3.367 5.6

232Th 232U 238U 238Pu

0.858 1001.145 99.3

dirdirdir, geodirdir, geodir, geodir

melking

dir

76Ge Heidelberg-Moscow (Gran-Sasso)

11 kg of 87 % 76Ge in 5 crystals

Energy [keV]

!CL%95yr10)18.469.0(T 2502/1

214Bi

total 71.7 kg yr SSE

Nucleus QRPA

Caltech

Shell model

Strasbourg-Madrid

exp

48Ca - 0.91 4.3 x 1019

76Ge 0.71 1.44 1.8 x 1021

82Se 1.5 0.46 8.0 x 1019

100Mo 0.6 - 1.0 x 1019

130Te 0.33 0.35 6.6 x 1020

128Te 0.27 0.25 2.0 X 1024

130Te 0.27 0.29 8.0 x 1020

136Xe <1.0 <2.6 >8.1 x 1020

pex

calc

T

T

2/1

2/1 )(22/1 yrT

pex

calc

T

T

2/1

2/1

direct

direct

geochem.

Baksan

23104.4

T1 20/ [ ] yr

( % )90 CL

m [ ]eV

QRPACaltech-Tübingen

Shell modelStrasbourg-Madrid

6.3 -

3.3 2.5

Ge76

Te130

Xe136

direct

2510)2.47.0( 25.014.0 23101.2

55.025.0

!eV5.0

?eV5.01.0|m|

Next experiments: large mass + low background, better signature, good energy resolution

NEMO 10 kg of 100Mo + … in tracking device

Majorana 500 kg of 86 % enriched 76Ge

10 cryostats with 21 crystals (2.4 kg each) , segmented readout

CUORICINO, 42kg , 760 kg 130Te, 56, 1000 crystals of TeO2, operated as

CUORE bolometers (8 mK)

GERDA 0.1, 1 t, 10 t of 76Ge crystals, immersed in lN2

EXO 200 kg, 1 t, 10 t of 136Xe in TPC

Enriched Xenon Observatory

for double beta decayAlabama, Caltech, Carleton, Colorado, UC Irvine, ITEP Moscow, Laurentian, Neuchatel, SLAC, Stanford

Ba+Ba+

system best studied (Neuhauser, system best studied (Neuhauser, Hohenstatt, Toshek, Dehmelt 1980)Hohenstatt, Toshek, Dehmelt 1980)Very specific signature “shelving” Very specific signature “shelving” Single ions can be detected from a Single ions can be detected from a photon rate of 10photon rate of 1077/s/s

22PP1/21/2

44DD3/23/2

22SS1/21/2

493nm493nm650nm650nm

metastable 47smetastable 47s

Much improved signature!

136136Xe: Xe: 136136Ba++ e- e- final state can be tagged usingBa++ e- e- final state can be tagged using optical spectroscopy optical spectroscopy (M.Moe PRC44 (1991) 931)(M.Moe PRC44 (1991) 931)

Isotopic enrichment for a gaseous substance like Xe is Isotopic enrichment for a gaseous substance like Xe is most economically achieved by ultracentrifugationmost economically achieved by ultracentrifugation

This separation step thatThis separation step thatrejects the light fractionrejects the light fractionis also very effective inis also very effective in

removing removing 8585Kr (TKr (T1/21/2=10.7 yr)=10.7 yr)that is present in the that is present in the

atmosphere from spentatmosphere from spentfuel reprocessingfuel reprocessing

Russia has enoughRussia has enoughproduction production

capacitycapacityto process 100 ton to process 100 ton

Xe and extract Xe and extract up to 10 ton up to 10 ton 136136Xe Xe

in a finite timein a finite time

Two detector options under considerationTwo detector options under consideration

High Pressure gas TPCHigh Pressure gas TPC• 5-10 atm, 50 m5-10 atm, 50 m33 modules, modules, 10 modules for 10 t10 modules for 10 t•Xe enclosed in a non-Xe enclosed in a non-structural bagstructural bag• range ~5-10cm: range ~5-10cm: can resolve 2 blobscan resolve 2 blobs•2.5m e-drift at ~250kV2.5m e-drift at ~250kV•Readout Xe scintillation withReadout Xe scintillation with WLSB (T0)WLSB (T0)•Additive gas: quenching and Additive gas: quenching and BaBa++ ++ BaBa+ + neutralizationneutralization•Steer lasers or drift Ba-ion to Steer lasers or drift Ba-ion to detection regiondetection region

Liquid Xe chamberLiquid Xe chamber•Very small detector (3mVery small detector (3m33 for for 10tons)10tons)•Need good E resolutionNeed good E resolution•Position info but blobs not Position info but blobs not resolvedresolved•Readout Xe scintillationReadout Xe scintillation•Can extract Ba from hi-density Can extract Ba from hi-density XeXe•Spectroscopy at low pressure:Spectroscopy at low pressure: 136136Ba (7.8% nat’l) different Ba (7.8% nat’l) different signature from natural Ba signature from natural Ba (71.7% (71.7% 138138Ba)Ba)•No quencher needed, No quencher needed, neutralization neutralization done outside the Xedone outside the Xe

x - yplane

anode(20 m)

potential(100 m)

grid

1 cm

liquid scintillator(veto+anti-Compton)

PMT

CF4 gasat 3 bar

acrylic vessel+field shaping rings

steel vessel

e

cathode(-45 kV)

reactor 18 m

reac

e-vD=2.3 cms

CH2+B

Pb1 m

Grenoble-Neuchâtel-Padova-Zurich (Bugey reactor)

M

U

N

U

-

proton

EM shower

xy

cmz

cm

cm

870 keV electron

X,Y = 1.7mm

1.7mm

M

U

N

U

MUNU measures reacand Te

e-, 232Th

(E)/E=3.4 % at 1.59 MeV

(E)/E= 2.7 % at 2.48 MeV

Gotthard 5 bar xenon

(from cathode), 210Po (238U chain)

quenching (/e-)=1/6.5

(E)/E=1.1 % at 2.48 MeV !

Energy resolution

/EF(E/W)E)/E(

F=0.19, W=22 eV

(E)/E=0.13 % at 2.48 MeV !

Micromegas

Woven mesh stainless steel

Neuchâtel-CERN:

CF4

1 bar 2 bar0 10 20 30 40 E(keV)

Ag

Fe

Fe

Agpulser pulser

0 10 20 30 E(keV)

Anode with spacers

Light detection (electroluminescence)in xenon (+CF4?)

Doped fibers : 1 step WLS UV (180 +/-20nm) to blue or 2 step WLS with coated fibers

e- track

Optical fibers x-y

Multianode photomultiplier

Grid (metallic cloth)

UV photons

Anode (charge)

Two gap scheme:Grid (metallic cloth)

anode

ITEP-Moscow, Kharkov, Neuchâtel

Fibers (250 m)

1 kV/cm

Found a clear (anti)correlation between ionization and scintillationFound a clear (anti)correlation between ionization and scintillation

~570 keV~570 keV

Major effort now: liquid xenon

Have demonstrated that we can get sufficient energyHave demonstrated that we can get sufficient energyresolution in LXe to separate the 2resolution in LXe to separate the 2νν from the 0from the 0νν modesmodes

We can do ionization measurements

as well as anyone

Now we turn on our newcorrelation technique…

Resolu

tions

Resolu

tions

at 5

70 keV

at 5

70 keV

3.3%@570keV3.3%@570keVor 1.6%@2.5MeVor 1.6%@2.5MeV

Fishing ions in LXeFishing ions in LXe

• Prototype Scale– 200 Kg enriched 136Xe– All functionality of EXO except Ba identification– Operate in WIPP for ~two years

• Prototype Goals– Test all technical aspects of EXO (except Ba id)– Measure 2 mode– Set decent limit for 0 mode (probe Heidelberg-

Moscow)

Massive materials qualification programled by Alabama with contributions from

Carleton, Laurentian and Neuchatel

•Approximate detector simulation with material properties to establish target activities•NAA whenever possible (MIT reactor + Alabama)•Direct Ge counting at Neuchatel, Alabama and soon Canada•High sensitivity mass spectroscopy starting in Canada•Alpha counting at Carleton and Stanford•Rn outgassing measurements starter at Laurentian (Xe plumbing)•Full detector simulation in progress

Vue-des-Alpes

400 cc germanium

Pb Plombum type VG2

0

20

40

60

80

100

120

0.00 250.00 500.00 750.00 1'000.00 1'250.00 1'500.00 1'750.00 2'000.00 2'250.00 2'500.00 2'750.00 3'000.00

Energy [keV]

Co

un

ts

Temps mesure : 1'116'322 sMasse : 34 kg

Pb Plombum VG2 13 days 34 kg

Spectre du Plomb de chez Plombum type VG2

0

0.5

1

1.5

2

2.5

1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 61 64 67 70 73 76 79 82 85 88 91 94 97 100

2601.11

2604.07

2611.61

2612.92

2613.25

2614.89

2616.86 2623.75 2625.06

2614 keV 208Tl (232Th chain)

Detector

(356 on each side, 16 mm diameter 120 % QE in UV))

APD plane below crossed wire array

100 APD channels (7 APD grouped together) provide light and t0

200 ionization channels (groups of wires 100 x +100 y)

Can define fiducial volume

Drift trajectories – crossed wires

Cryostat Cross Section

Condenser

Xenon Heater

should be

on this area

Xenon

Chamber

Outer Copper Vessel

Inner Copper Vessel

FC-87

FC-87

1” thick Thermal Insulation (MLI-vacuum), not shown to scale

Outer Door

Inner Door

Xenon

Chamber

Support

Full detector viewWith Pb shielding

DoE’s Waste Isolation Pilot Plant (WIPP), Carlsbad NM

Assuming

1) that the Xe chamber + Ba tagging gives 0 background from radioactivity...2) that the energy resolution is (E)/E=2 % (2!)

Conclusion:

With a coordinated effort, the meV region is within reach!

Mass Enrichment Eff. Time Background

(kg) (%) (%) (yr) (events) (yr) QRPA SM1000 90 70 5 0.3 0.05 0.0810000 90 70 10 5.5 0.02 0.03

T1/2

0 <m> (eV) <m

> (eV)

2*1027

1.3*1028

Status

• Enriched Xe in hand.

• Clean rooms in commercial production.

• WIPP agreement, including Environmental Impact, complete.

• Cryostat being designed.

• Xe purification and refrigeration issues being finalized

• Detector vessel, readout, and electronics being engineered.