Transcript Solar Neutrinos: Current Implications and Future Possibilities CENPA - Solar neutrinos

Solar Neutrinos: Current Implications
and Future Possibilities
- Solar neutrinos
SNO
- Reactor antineutrinos
KamLAND
- Future Possibilities
solar neutrinos
b-decay
bb-decay
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CENPA
Center for Experimental Nuclear Physics and Astrophysics
J. F. Wilkerson
March 20, 2003
Fermilab -- NUHORIZONS
Our “accelerator” - the Sun
1854 von Helmholtz postulates
gravitational energy
SSM Energy Generation
1920’s Eddington proposes
p + p fusion
“We do not argue with the critic
who urges that the stars are not
hot enough for this process; we
tell him to go and find a hotter
place.”
1938 Bethe & Critchfield
p + p  2H + e+ + e
p + p 2H + e+ + e
2H
3He
7Be
+ p 3He + 
+ 3He 4He + 2p
3He
+p+
3He
+ p  + e+ + e
+  7Be + 
+ e- 7Li +  +e
7Li
p + e- + p  2H + e
7Be
8B
+ p 8B + 
 2  + e+ +  e
Using solar s’ to probe the Sun
1946 Pontecorvo,1949 Alvarez
37Cl
+ e 
37Ar
+ e-
SSM Energy Generation
p + p 2H + e+ + e
2H
3He
7Be
+ p 3He + 
+ 3He 4He + 2p
3He
+p+
3He
+ p  + e+ + e
+  7Be + 
+ e- 7Li +  +e
7Li
p + e- + p  2H + e
7Be
8B
+ p 8B + 
 2  + e+ +  e
Using solar s’ to probe the Sun
1946 Pontecorvo,1949 Alvarez
37Cl
+ e 
37Ar
+ e-
1960’s
Ray Davis, builds
Chlorine detector
John Bahcall, generates
SSM &  flux predictions
“…to see into the interior of a star
and thus verify directly the
hypothesis of nuclear energy
generation in stars...”
Solar  Flux
Measurement
Results
  flux
~ 6.5 • 1010/cm2/s
Astrophysical Solutions?
SSM Energy Generation
p + p 2H + e+ + e
2H
3He
7Be
+p+
3He
+ p  + e+ + e
+  7Be + 
+ e- 7Li +  +e
7Li
p + e- + p  2H + e
+ p 3He + 
+ 3He 4He + 2p
3He
Hata and Langacker
7Be
8B
+ p 8B + 
 2  + e+ +  e
The data are incompatible with standard and nonstandard solar models
Super-Kamiokande
(hep-ex/0103032)
Elastic Scattering: x + e-  x + e+0.08
ES = 2.32 ± 0.03 - 0.07 (106 cm-2 s-1)
(stat) (sys.)
Data/SSM = 0.451 ± 0.005
+0.016
- 0.014
(stat) (sys.)
Gallium Measurements
71Ga
+ e 
71Ge
+ e-
Both Expts Performed
 source tests
Two independent experiments
51Cr
SAGE Data/SSM = 0.55 ± 0.05
GALLEX Data/SSM = 0.57 ± 0.05
Latest SAGE results (astro-ph/0204245)
SSM
+ e- 
51V
+ e
Gallium Measurements
71Ga
+ e 
71Ge
+ e-
Both Expts Performed
 source tests
Two independent experiments
51Cr
SAGE Data/SSM = 0.55 ± 0.05
GALLEX Data/SSM = 0.57 ± 0.05
Latest SAGE results (astro-ph/0204245)
SSM
+ e- 
51V
+ e
Gallium Measurements
71Ga
+ e 
71Ge
+ e-
Both Expts Performed
 source tests
Two independent experiments
51Cr
SAGE Data/SSM = 0.55 ± 0.05
GALLEX Data/SSM = 0.57 ± 0.05
+ e- 
51V
+ e
SAGE Source Test
R(smea/sth)=0.95±.12±.03
Latest SAGE results (astro-ph/0204245)
SSM

Beyond the Standard Model -  mass & mixing
Vacuum Oscillations
Small splittings in mass can
lead to large observable phase
differences in Q.M. amplitude.
If neutrinos have mass then the lepton
mixing matrix (Maki-Nakagawa-SakataPontecorvo, or MNSP) is no longer a
 e 
 
   
 
  

U e1 U e2 U e 3   1 

  
U
U
U

1

2

3

  2 

  
U1 U 2 U 3   3 
Oscillation experiments yield
mass squared differences:
m122  m21  m2 2
trivial representation and flavor eigenstates are a mixture of mass eigenstates.
Then

 e  U e1 1  U e 2 2  U e 3 3
and the state evolves with time or distance
 e  U e1eiE t1  U e 2eiE t 2  U e 3e iE t 3
1
2
2
2
where E i  p  mi
2
2
m23
 m22  m2 3
3


m132  m21  m2 3
(See B. Kayser hep-ph/0104147
for a nice introduction)
Sensitivity of experiments to  oscillations
For simple case of mixing between
two  mass eigenstates
2
P i  j  4 U i2 U j 2
P i  j
2
1.27m2 L 
12
sin 

E


2
1.27m2 (eV) L(km) 
 sin 2 2 sin 2

E
(GeV)



102
1
10-2
10-4
10-6
10-8
10-10
Accelerator [~GeV]
m2
(eV2 )
Reactor [~MeV]
Atmospheric [~GeV]
Solar [~MeV]
L/E
(km/GeV)
10-2
1
102
104
106
108
1010
Sensitivity of experiments to  oscillations
For simple case of mixing between
two  mass eigenstates
2
P i  j  4 U i2 U j 2
P i  j
2
1.27m2 L 
12
sin 

E


2
1.27m2 (eV) L(km) 
 sin 2 2 sin 2

E
(GeV)



102
1
10-2
10-4
Matter Enhanced
Oscillations (MSW)
s in matter can acquire an
effective mass through scattering
(analogous to index of refraction for
light in transparent media)
10-6
10-8
10-10
Accelerator [~GeV]
m2
(eV2 )
Reactor [~MeV]
Atmospheric [~GeV]
Solar [~MeV]
MSW
L/E
(km/GeV)
10-2
1
102
104
106
108
1010
Mikhevev, Smirnov, Wolfenstein Effect
Matter Enhanced
Oscillations
s in matter can acquire an
effective mass through scattering
(analogous to index of refraction for
light in transparent media)
Normal Matter contains many
electrons, but no muons or taus, so
e can undergo both CC and NC
scattering. Have QM two-state
level crossing and flavor change.
MSW Oscillations are dependent
on the  energy and the density of
the material, hence one can
observe spectral energy distortions.
e
e
Z
W
e
e
e
e
x
x
Matter Enhanced  Oscillations
MSW gives a dramatic
extension of oscillation
sensitivity to potential
regions in m2
Solar  data are
consistent with the
MSW hypothesis.
LMA
SMA
LOW
But only circumstantial
evidence
• Need definitive proof
• Appearance measurement
• Independent of SSM
SAGE & GALLEX
Kamiokande
Homestake
The SNO Collaboration
G. Milton, B. Sur
Atomic Energy of Canada Ltd., Chalk River Laboratories
J.D. Anglin, M. Bercovitch, W.F. Davidson, R.S. Storey*
National Research Council of Canada
S. Gil, J. Heise, R.J. Komar, T. Kutter, C.W. Nally, H.S. Ng,
Y.I. Tserkovnyak, C.E. Waltham
University of British Columbia
J.C. Barton, S. Biller, R.A. Black, R.J. Boardman, M.G. Bowler,
J. Cameron, B.T. Cleveland, X. Dai, G. Doucas, J.A. Dunmore,
H. Fergani, A.P. Ferrarris, K. Frame, N. Gagnon, H. Heron, N.A. Jelley,
A.B. Knox, M. Lay, W. Locke, J. Lyon, S. Majerus, G. McGregor,
M. Moorhead, M. Omori, C.J. Sims, N.W. Tanner, R.K. Taplin,
M.Thorman, P.M. Thornewell, P.T. Trent, N. West, J.R. Wilson
University of Oxford
J. Boger, R.L Hahn, J.K. Rowley, M. Yeh
Brookhaven National Laboratory
R.C. Allen, G. Bühler, H.H. Chen*
University of California, Irvine
I. Blevis, F. Dalnoki-Veress, D.R. Grant, C.K. Hargrove,
I. Levine, K. McFarlane, C. Mifflin, V.M. Novikov, M. O'Neill,
M. Shatkay, D. Sinclair, N. Starinsky
Carleton University
T.C. Andersen, P. Jagam, J. Law, I.T. Lawson, R.W. Ollerhead,
J.J. Simpson, N. Tagg, J.-X. Wang
University of Guelph
J. Bigu, J.H.M. Cowan, J. Farine, E.D. Hallman, R.U. Haq,
J. Hewett, J.G. Hykawy, G. Jonkmans, S. Luoma, A. Roberge,
E. Saettler, M.H. Schwendener, H. Seifert, R. Tafirout,
C.J. Virtue
Laurentian University
Y.D. Chan, X. Chen, M.C.P. Isaac, K.T. Lesko, A.D. Marino,
E.B. Norman, C.E. Okada, A.W.P. Poon, S.S.E Rosendahl,
A. Schülke, A.R. Smith, R.G. Stokstad
Lawrence Berkeley National Laboratory
M.G. Boulay, T.J. Bowles, S.J. Brice, M.R. Dragowsky,
M.M. Fowler, A.S. Hamer, A. Hime, G.G. Miller,
R.G. Van de Water, J.B. Wilhelmy, J.M. Wouters
Los Alamos National Laboratory
E.W. Beier, D.F. Cowen, M. Dunford, E.D. Frank, W. Frati,
W.J. Heintzelman, P.T. Keener, J.R. Klein, C.C.M. Kyba, N. McCauley,
D.S. McDonald, M.S. Neubauer, F.M. Newcomer, S.M. Oser, V.L Rusu,
S. Spreitzer, R. Van Berg, P. Wittich
University of Pennsylvania
R. Kouzes
Princeton University
E. Bonvin, M. Chen, E.T.H. Clifford, F.A. Duncan, E.D. Earle,
H.C. Evans, G.T. Ewan, R.J. Ford, K. Graham, A.L. Hallin,
W.B. Handler, P.J. Harvey, J.D. Hepburn, C. Jillings, H.W. Lee,
J.R. Leslie, H.B. Mak, J. Maneira, A.B. McDonald, B.A. Moffat,
T.J. Radcliffe, B.C. Robertson, P. Skensved
Queen’s University
D.L. Wark
Rutherford Appleton Laboratory, University of Sussex
R.L. Helmer, A.J. Noble
TRIUMF
Q.R. Ahmad, M.C. Browne, T.V. Bullard, G.A. Cox, P.J. Doe,
C.A. Duba, S.R. Elliott, J.A. Formaggio, J.V. Germani,
A.A. Hamian, R. Hazama, K.M. Heeger, K. Kazkaz, J. Manor,
R. Meijer Drees, J.L. Orrell, R.G.H. Robertson, K.K. Schaffer,
M.W.E. Smith, T.D. Steiger, L.C. Stonehill, J.F. Wilkerson
University of Washington
The Sudbury Neutrino Observatory
CC
e  d  p  p  e
-
-Good sensitivity to e energy spectrum
-Weak directional sensitivity  1-1/3cos()
- e only.
NC
 x  d  p  n  x
- Measure total 8B  flux from the sun.
- Equal cross section for all  types
- 2.2 MeV Threshold, Integrated E > Eth
ES
- 


e
e
x
x
-Low Statistics
-Dominant contribution (5/6) from e,,
smaller (`1/6) contributions from  & 
-Strong directional sensitivity
Key signatures for unexpected  Flavors
Measure total flux of solar neutrinos vs. the pure e flux
Direct
Evidence
for  flavor
change
cc
es
Potential signal
For  oscillations
=
e
e + 0.154( + )
cc
nc
day
=
e
e +  + 
vs
night
June 2001
April 2002
April 2002
The SNO Detector during Construction
The SNO Detector during Construction
The SNO Detector during Construction
The SNO Detector during Construction
 Reactions in SNO
CC
 e  d  p  p  e-
-Good measurement of e energy spectrum
-Weak directional sensitivity  1-1/3cos()
- e only.
NC
 x  d  p  n  x
- Measure total 8B  flux from the sun.
- Equal cross section for all  types
- 2.2 MeV Threshold, Integrated E > Eth
ES
x  e-  x  e -
Produces Cherenkov
Light Cone in D2O
D2O Only Phase
n captures on deuteron
2H(n, )3H
Observe 6.25 MeV 
Produces Cherenkov
Light Cone in D2O
-Low Statistics
-Mainly sensitive to e,, some sensitivity to  and 
-Strong directional sensitivity
Extraction of CC, ES, NC Signals
To extract the CC,
ES, NC signal SNO
performs a Maxlikelihood statistical
separation of these
signals based on
distributions of the
SNO observables.
#EVENTS
Shape Constrained Signal Extraction Results
CC 1967.7
+61.9
+60.9
ES
263.6 +26.4
+25.6
NC
+49.5
+48.9
576.5
First result
Eth of 6.75 MeV
SNO NC in D2O Conclusions
~ 2/3 of initial solar e are observed at SNO to be ,
Rule out null
hypothesis - no
flavor change at 5.3 s level.
ssm = 5.05 +1.01
-0.81
+0.46
sno = 5.09+0.44
-0.43 -0.43
SNO Signal Extraction in CC, NC, ES
Etn = 5 MeV
8B
from CCSNO+ESSK
ESSNO
CCSNO
April 2002
NCSNO
ESSNO
CCSNO
Neutrino Signal (SSM BP00)
June 2001
Neutral
Current (NC)
2.0
SSM
1.0
5.3 s
0.5
CC shape
unconstrained
cc(e) = 1.76
+0.44 +0.46
-0.43
CC shape
constrained
1.5
0.0
NC(e) = 5.09 -0.43
Elastic
Charged
Scattering (ES) Current (CC)
x106 cm-2s-1
e+ + e+ 0.15 (+)
e
+0.06 +0.09
-0.05
-0.09
x106 cm-2s-1
es(e) = 2.39
+0.24 +0.12
-0.23
-0.12
x106 cm-2s-1
SNO Conclusions
• First NC flux measurements - clear
evidence that the majority of e
produced in the Sun are transformed
to  and/or 
• Null hypothesis - “No Weak Flavor
Mixing” ruled out at 5.3 s
• Lowest Detection threshold yet for a
real-time solar  detector
• Total 8B flux measurement agrees well
with Solar Models
• Data in good agreement with previous
SNO - SK CC/ES result
• First measurements of the
Day-Night Asymmetries
• SNO Data consistent with MSW
oscillation interpretation
• combined with global solar neutrino data
favors LMA solution
• “Dark side” solutions not allowed,
indicating m2 > m1
nucl-ex/0204008, nucl-ex/0204009
Combining All Experimental
and Solar Model information
Reactor e oscillation searches
1956 Reines & Cowan
+
p
n
e


e 
Chooz hep-ex/9907037
Disappearance experiments
Solar neutrino LMA implication
Reactor experiments optimum at ~180 km
Solar LMA best fit
prediction
KamLAND Collaboration
G.A.Horton-Smith, R.D.McKeown, J.Ritter, B.Tipton,
P.Vogel
California Institute of Technology
C.E.Lane, T.Miletic
Drexel University
Y-F.Wang
IHEP, Beijing
T.Taniguchi
KEK
B.E.Berger, Y-D.Chan, M.P.Decowski, D.A.Dwyer,
S.J.Freedman, Y.Fu, B.K.Fujikawa, K.M. Heeger,
K.T.Lesko,K-B.Luk, H.Murayama, D.R.Nygren, C.E.Okada,
A.W.Poon, H.M.Steiner, L.A.Winslow
LBNL/UC Berkeley
S.Dazeley, S.Hatakeyama, R.C.Svoboda
Louisiana State University
J.Detwiler, G.Gratta, N.Tolich, Y.Uchida
Stanford University
K.Eguchi, S.Enomoto, K.Furuno, Y.Gando, J.Goldman,
H.Ikeda, K.Ikeda, K.Inoue, K.Ishihara, T.Iwamoto,
T.Kawashima, Y.Kishimoto, M.Koga, Y.Koseki,
T.Maeda, T.Mitsui, M.Motoki, K.Nakajima, H.Ogawa,
K.Oki, K.Owada, I.Shimizu, J.Shirai, F.Suekane,
A.Suzuki, K.Tada, O.Tajima, K.Tamae, H.Watanabe
Tohoku University
L.DeBraeckeleer, C.Gould, H.Karwowski, D.Markoff,
J.Messimore, K.Nakamura, R.Rohm, W.Tornow,
A.Young
TUNL
J.Busenitz, Z.Djurcic, K.McKinny, D-M.Mei, A.Piepke,
E.Yakushev
University of Alabama
P.Gorham, J.Learned, J.Maricic, S.Matsuno,
S.Pakvasa
University of Hawaii
B.D.Dieterle
University of New Mexico
M.Batygov, W.Bugg, H.Cohn, Y.Efremenko,
Y.Kamyshkov, Y.Nakamura
University of Tennessee
KamLAND - Kamioka Liquid
Scintillator Anti-Neutrino
Detector
16 complexes - 10% of
world’s nuclear power
3 GW reactor: ~8 • 1020 e/s
L ~140 - 210 km
KamLAND - Kamioka Liquid
Scintillator Anti-Neutrino
Detector
16 complexes - 10% of
world’s nuclear power
3 GW reactor: ~8 • 1020 e/s
L ~140 - 210 km
KamLAND first results (hep-ex/0212021)
• Data summary
– 145.1 live days
– Observed: 54
– Expected: 86.8 ± 5.6
– Background 1 ± 1
Measured survival probability
differs from 1 by 4.1 s
Probability that result is consistent with no
oscillation hypothesis < 0.05%
Evidence of e oscillations
KamLAND with LMA shown
Global fit
(de Holanda and Smirnov)
CL: 1s, 90%, 95%, 99%, 3s
CL: 95%
hep-ex/0212021
hep-ph/0212270
Current situation
• Atm. , Solar , & KamLAND
provide compelling evidence
for oscillations.
• LSND awaits confirmation by
miniBoone.
• Big surprise - unlike quark
sector (CKM), lepton sector
has large mixing angles.
• Osc. Results yield a LOWER
BOUND on m ; tritium beta
decay, astrophysical data set
UPPER BOUND
What’s next?
_
_
  s  e
  
e  
Solar  &
KamLAND
 physics - issues & questions
• accurate determinations of ij, m2ij
– especially 13
•
•
•
•
•
•
•
CP violation phases
Majorana/Dirac character of the neutrinos
absolute scale of neutrino mass
magnetic and other neutrino moments
existence of, constraints on sterile neutrinos
inverted or regular hierarchy?
role of neutrinos in nucleosynthesis, supernova
explosions, BBN
• lepton number violation
• baryogenesis via leptogenesis
Non-accelerator  physics - future possibilities
• Solar neutrinos
– More accurate determination of 12
– potential independent observation of oscillations
• day/night effect
• low energy 7Be & pp shape effects
– Astrophysics (pp flux, CNO cycle)
• Single b-decay(endpoint measurement)
– absolute scale of neutrino mass
• 0  bb-decay
– Majorana/Dirac character of the neutrinos
– absolute scale of neutrino mass
– inverted or regular hierarchy?
• Atmospheric neutrinos - covered by Kearns
• Reactor neutrinos - will be covered by Gratta
Future Possibilities for Solar Neutrinos
Solar neutrinos - immediate future
– SNO entering precision phase of experiment
• Salt measurements underway since June 2001
• 3He proportional neutral current detectors (Fall 2003)
• Some possibility of observing day/night effect - and hence
direct oscillation signature
SNO - Current Status and Future Plans
The Salt Phase
n  35Cl  36Cl   …  e (E = 8.6 MeV)
•Higher n-capture efficiency
•Higher event light output
•Event isotropy differs from e•Running since June 2001
Neutral Current Detectors
n  3He  p  t
• Event by event separation
• Different systematics
Impact of precision SNO
• Improved NC/CC measurement will yield an improved
12 value (red ---- lines)
• D2O: unconstrained ~30%
•
•
Salt: perhaps 10-15%
NCD: potentially ~5 %
• Note KamLAND should
improve on m12
• Possible chance to observe
Day/Night asymmetry and
hence direct oscillation
siganl
de Holanda and Smirnov
hep-ph/0212270
MSW and Day-Night Fluxes
Certain MSW oscillation
solutions predict s can
change flavor while
passing through the earth
Define Asymmetry
Ax = 2*(N,X – D,X)
(N,X + D,X)
SNO Ae and Atot Measurements
Signal Extraction in CC, NC, ES.
Acc = 14.0 +- 6.3 +1.5
-1.4
Anc = -20.4 +- 16.9+2.4
-2.5
Signal Extraction in e, total,  Atotal = 0
Ae
= 7.0 +- 4.9 +1.3
-1.2
Aesk = 5.3 +- 3.7 +2.0
-1.7
Impact of precision SNO
• Improved NC/CC measurement will yield an improved
12 value (red ---- lines)
• D2O: unconstrained ~30%
•
•
Salt: perhaps 10-15%
NCD: potentially ~5 %
• Note KamLAND should
improve on m12
• Possible chance to observe
Day/Night asymmetry and
hence direct oscillation
siganl (blue -- lines)
– limited by statistics
– Depends on real solution
de Holanda and Smirnov
hep-ph/0212270
Future Possibilities for Solar Neutrinos
Solar neutrinos - immediate future
– SNO entering precision phase of experiment
• Salt measurements underway since June 2001
• 3He proportional neutral current detectors (Fall 2003)
• Some possibility of observing day/night effect - and hence
direct oscillation signature
– KamLAND solar  and Borexino (2004?) real-time 7Be
( KamLAND initial backgrounds look promising for solar 
measurements)
• Independent confirmation of LMA solution
• Confirmation of solar model, slight improvement on CNO limit
Next generation experiments (pp in real-time)
Next generation Solar Neutrinos
Charged-Current Experiments:
LENS, MOON
Goal: Measure e component of pp (7Be)
with 1-3% (2-5%) accuracy
Elastic Scattering Experiments:
CLEAN, HERON, TPC
XMASS (Japan)
Goal: Measure e / , 
component of p-p (7Be)
with 1-3% (2-5%) accuracy
Projected
Future Possibilities for Solar Neutrinos
Solar neutrinos - immediate future
– SNO entering precision phase of experiment
• Salt measurements underway since June 2001
• 3He proportional neutral current detectors (Fall 2003)
• Some possibility of observing day/night effect - and hence direct
oscillation signature
– KamLAND solar  and Borexino (2004?) real-time 7Be
( KamLAND initial backgrounds look promising for solar  measurements)
• Independent confirmation of LMA solution
• Confirmation of solar model, slight improvement on CNO limit
Next generation experiments (pp in real-time)
•
•
•
•
12 to 1%
CPT- potentially more sensitive than kaon system
~10 x improvement on neutrino magnetic moment sensitivity
Confirmation of solar model, slight improvement on CNO limit
“…to see into the interior of a star and thus verify directly
the hypothesis of nuclear energy generation in stars...”
The absolute scale of  masses
• Addresses key issues in particle physics
– hierarchical or degenerate neutrino mass spectrum
– understanding the scale of new physics beyond SM
– potential insight into origin of fermion masses
• Impacts cosmology and astrophysics
– early universe, relic neutrinos (HDM), structure formation,
anisotropies of CMBR
– supernovae, r-process, origin of elements
– potential insight on understanding the origin of UHE cosmic rays
sub-eV absolute  mass measurements
hierarchical
degenerate
m 1  m 2  m3
m 1  m 2  m3
e
nµ
nt
Given the surprise of large mixing in the lepton sector, there is
limited theoretical insight into which scenario occurs in nature.
Probes of absolute  mass
• Indirect methods
– Cosmology
•
•
•
•
CMB
Galaxy clusters
Lyman- forest
Galaxy large scale structure
– Astrophysics
• UHE cosmic-rays
• Supernovae generation mechanisms
– Neutrinoless bb-decay
m = 0 eV
m = 10 eV
18.56
18.58
Energy (keV)
0
2000 4000 6000 8000 10000 12000 14000 16000 18000
Electron Energy (eV)
Kurie Amplitude
18.54
Decay Probability
– time of flight (supernovae)
– particle decay kinematics
Kurie Amplitude
• Direct techniques
Past: history of direct  mass measurements
( flavor eigenstates)
Mass Limit (eV, keV, or MeV)
10
10
4

3
m < 170 keV (90%CL)
e
10
(PSI 1996)
2

10
m < 18.2 MeV (95% CL)
(ALEPH 1998)
e (eV)
 (keV)
 (MeV)
1
me < 2.2 eV (95% CL)
(Mainz 2000)
10
0
1950
1960
1970
1980
1990
Year
points without error bars represent upper limits
2000
Past: history of direct  mass measurements
( flavor eigenstates)
Mass Limit (eV, keV, or MeV)
10
10
4

3
But  oscillations
mwith
keV
(90%CL)
 < 170
large
mixing
(PSI 1996)
angles - forces one
to consider
m
< 18.2 MeV (95% CL)

(ALEPH 1998)
direct techniques
in terms of  mass
me < 2.2 eV (95% CL)
eigenstates!
(Mainz 2000)
e
10
2

10
10
e (eV)
 (keV)
 (MeV)
1
0
1950
1960
1970
1980
1990
Year
points without error bars represent upper limits
2000
b-decay endpoint measurement
Essentially a search for a distortion in the shape
of the b-spectrum in the endpoint energy region
dN(E) =
K|M|2F(Z,R,E)
peE (E0-E)  |Uei {
i
|2
2
2
(E0-E) -mic4 1/2 dE
}
For 3  mass spectrum, with degenerate states, the beta spectrum
simplifies to an “effective mass” : mb 2 =  |Uei |2 m
Karlsruhe Tritium Neutrino Experiment
(KATRIN)
~ .2 eV sensitivity
arXiv:hep-ex/0109033
KATRIN

0 bb-decay

n  p  e  e
(RH  e )
(LH e )
e  n  p  e

Crucial Challenge - measuring extremely rare decay rates:
T1/2 ~ 1026 - 1027 years
bb(0) relationship to neutrino mass
 G M
0
0 0
2
m
2
bb
3
mbb   Uei mi  i
i 1
nuclear matrix elements uncertainty on  mass ~ 2-3

2
0 bb-decay - next generation
• probe lepton number violation and the charge
conjugation properties of s
• best sensitivity to neutrino mass
Two Neutrino Spectrum
Zero Neutrino Spectrum
1% resolution
(2 ) = 100 * (0 )
Theoretical caveats:
• Requires that neutrinos be Majorana particles
0.0
0.5
1.0
1.5
Sum Energy for the Two Electrons (MeV)
Key requirements for next generation experiments:
• Sufficient mass, ~ 1 ton
• Extremely low backgrounds
• Good energy resolution
2.0
0 bb-decay status
Current situation is a bit “muddled”
Heidelberg-Moscow Klapdor-Kleingrothaus et al. Eur. Phys. J. A12 147 (2001).
For 76Ge
T1/2 > 1.9  1025 y (90% CL)
<mbb> < 0.39 eV (90% CL).
Klapdor-Kleingrothaus et al. (Klapdor-Kleingrothaus et al. Mod. Phys. Lett. 16
2409 (2001). reported a non-zero result with a best value of
1.5  1025 y (~2.2 s)
<mbb> = 0.11 - 0.56 eV
See hep-ex/0202018
and hep-ph/020191
for comments
0 bb-decay prospects
Next Generation Double Beta Decay Experiments
Isotope Experiment
48
Ca
76
Ge
76
Ge
76
Ge
CANDLES
GEM
GENIUS
MAJORANA
82
100
Se, Mo, NEMO3
116
150
Cd,
100
116
Cd
Cd
130
Te
Te
130
Te
136
Xe
136
Xe
136
Xe
150
Nd
160
Gd
130
CaF2 crystals in li q. scint.
Ge diodes in LN
Ge diodes in LN
Segmented Ge crys tals
drift cha mber-scintil lator
Nd
Mo
116
Technique
Scint+Foils (or Bolometer)
MOON
CdWO4 - Borexino CTF
CAMEO
CdWO4
CWO
CdZnTe or TeO2 semi conduc tors
COBRA
Cryogen ic TeO2 crystals
CUORICINO
Cryoge nic TeO2 crys tals
CUORE
Liquid Xe
EXO
Xe in li quid scintil lator
Xe
li quid Xe (solar )
XMASS
foils and tracking chambers
DCBA-II(2)
Gd 2SiO5 :Ce crystal scint. in li q. scint.
GSO
Isotope Enriched Qb b Expected
(MeV) Sensitivity
Mass (t)
0
T1/2
(y)
~1-3
1
1
.5
.001, .007 ,
.001, .001
34
~1
~1
.01
.04
.75
1-10
1.6
10
.02
2
No
Yes
86%
86%
Yes
No
Yes
Yes
No
No
No
Yes
Yes
No
Yes
No
4.27
2.04

2.04
2.04
3.0,3.0,
2.8,3.4
3.03
2.8
2.8
2.6
2.6
2.6
2.47
2.47
2.47
3.37
1.73
1 x 1026
7 x 1027
1 x 1028
3 x 1027
4 x 1024
1 x 1027
> 10 27
1 x 1026
1 x 1024
1 x 1024
2 x 1026
8 x 1026
5 x 1026
3 x 1026
2 x 1025
2 x 1026
The need for a national underground
laboratory?
Compelling forefront science with a broad impact
– the nature of neutrinos, astrophysics, supernova, dark matter,
nucleon decay, nuclear astrophysics, origin of elements, biology...
Opportunity to establish the world’s deepest and most
extensive science laboratory within the United States
aimed at the future generations of underground
science experiments.
– Shortage of space in existing facilities.
– Several existing experiments would be “better” if deeper.
– Success of SNO cleanliness demonstrates that one can build ultra
clean detectors deep underground.
– New generation experiments will gain from depth.
– Establishment would indicate a clear leadership role for the US in
underground science
– Range of scientific fields and “cutting edge” research will facilitate
learning opportunities for K-Ph.D. students in a multitude of
academic disciplines as well as affording excellent outreach
opportunities to the American public.
Making the Science Case for NUSEL
• Nuclear Science Advisory Committee (NSAC)
Long Range Plan
2000 - 2001
• Committee on an Underground Scientific Laboratory
2000 - 2001 (Community committee, NSF & DOE)
• HEPAP Sub-panel on Long Range Planning
2000-2001
• NRC Committee on the Physics of the Universe (CPU)
2000-2002
• NRC - Neutrino Facilities Assessment Committee
March - December 2002
Summary
Solar , reactor  and atmospheric  demonstrate that
neutrinos have mass and the Standard Model of Nuclear
and Particle Physics is incomplete.
– Unlike the Quark Sector where the CKM mixing angles are small, the
lepton sector exhibits large mixing
– The  masses and mixing may play significant roles in determining
structure formation in the early universe as well as supernovae dynamics
and the creation of the elements
Future possibilities
– Solar neutrinos
• improve 12 , further confirmation of LMA astrophysics
– Single beta decay - direct neutrino mass measurements
• KATRIN should reach ~0.2 eV sensitivity
– 0  bb-decay - discovery potential of Majorana neutrinos
• Next generation should reach 20-50 meV sensitivity