Transcript Beta Decay: A Physics Garden of Earthly Delights APS April Meeting, April 8, 2014 Savannah, GA Hamish Robertson, CENPA, University of Washington.

Beta Decay: A Physics Garden of
Earthly Delights
APS April Meeting, April 8, 2014
Savannah, GA
Hamish Robertson, CENPA, University of Washington
The Garden of Earthly Delights (Hieronymus Bosch, ca. 1506)
214Pb
J. Chadwick, Intensitaetsverteilung
im magnetische Spektren der βStrahlen von Radium B + C. Verh.
d. D. Phys. Gesell. 16 (1914) 383391
+ 214Bi
The Neutrino is Summoned by Pauli...
210Bi
e210Po
210Bi
e-
ne
210Po
1930
4
“The … theory of β decay was worked out in
late 1933 by the Italian physicist Enrico
Fermi. Fermi was much occupied … with
second quantization … and argued that the
simplest possible Hamiltonian was
H = g {Qy (x)j (x)+Q y (x)j (x)}
*
*
*
g – strength of interaction
Q – transition operator from proton to neutron
x – coordinates of protons, neutrons
φ, ψ – field operators of electron and neutrino
“Combinations of the field operators give 5 relativistic
covariants: scalar, vector, tensor, pseudoscalar, axial
vector.”
C. Jensen, Controversy and Consensus (Birkhäuser, 2000)
5
Franco Rasetti recalls that Fermi had intended to announce
his results in a letter to Nature in November, but the
manuscript was rejected by its editor on the grounds that it
contained abstract speculations too remote from physical
reality to be of interest to its readers. Instead, Fermi
published a short paper on his theory in Ricerca Scientifica,
and a much longer paper on it in both Nuovo Cimento and
Zeitschrift für Physik in early 1934.
C. Jensen, Controversy and Consensus (Birkhäuser, 2000)
6
“Hence, we conclude that the rest mass of the neutrino is
either zero, or, in any case, very small in comparison to the
mass of the electron.”
F. Wilson, Am. J. Phys. 36, 1150 (1968)
7
Neutrinos are never
mentioned!
Fermi theory allows Bethe to
explain sun’s energy (1938)
8
“I have created a particle that can never be detected…” W. Pauli
Victory at last at
Savannah River!
9
Ray Davis and John Bahcall
with the first solar neutrino
detector
Wu et al. Phys. Rev. 105, 1413 (1957)
10
•
•
•
•
Chiral Lagrangian (after Lee-Yang 2-component neutrino)
VA intrinsic
Conserved Vector Current.
Confidence Rustad & Ruby had to be wrong.
11
Eβ= 1.25 MeV
α = +0.36(11)
Eβ= 2.0 MeV
α = +0.31(14)
W(qen ) = (1+ ab cosqen )
Rustad & Ruby (1955): e-v correlation in 6He β decay showed
interaction is Tensor, not Axial Vector (!)
12
n
152mEu
source
Coil
0Electron
capture
1-
Fe
g
152mEu
The neutrino is
left-handed:
961
837
30 fs
s · pˆ = -1
Pb
2+
0+
Sm2O3
152Sm
Helicity of the
neutrino
g detector
Goldhaber , Grodzins, & Sunyar, PR 109, 1015 (1958)
13
Are neutrinos coming from the sun?
Ray Davis and John Bahcall with the first solar neutrino
detector
p + p  d + e+ + ne
ne
“d + d  4He + g”
+26 MeV
14
Solar neutrino problem: new
neutrino physics
Cl - Ar
SNO
8.59 +1.1 -1.2
Modern Times
What CAN we measure?
• Absolute rate
Unpolarized example:
– Vud
• Spectrum shape (allowed)
æ
m
pe × pn ö
w(Ee ) = w0 (Ee )x ç1+ b + a
÷
Ee
Ee En ø
è
– mv , Fierz interference
• 6 double and 4 triple correlations
– Scalar, tensor BSM contributions
(all CP-even)
(all CP-odd)
Naviliat-Cuncic & Gonzalez-Alonso, Ann. Phys. 525, 600 (2013)
17
What CAN we know?
19 parameters, but only 6 dominate:
Re(e L + e R )
Re(eS )
Re(eT )
modifies Vud
Fierz term, CP-even correlations
Im(eS )
Im(eT )
CP-odd correlations
Im(e R )
…plus neutrino mass.
Naviliat-Cuncic & Gonzalez-Alonso, Ann. Phys. 525, 600 (2013)
Results from β decay and LHC
Present: 90% CL (in units 10-2)
Cirigliano, Gardner, Holstein: Prog.Part.Nucl.Phys. 71,93 (2013)
Future: 0.1% in B, b
from neutron, and in b
from 6He decay.
Superallowed 0+  0+ β decay
Tz=0
Tz=-1
20
Hardy & Towner, PRC 71:055501 (2005)
Cirigliano & Neufeld, PL B700, 7 (2011)
2014:
Hardy & Towner, PRC 71:055501 (2005)
2004:
Antonelli et al. Eur. Phys. J. C69, 399 (2010)
21
Neutron Decay Correlations
g A / gV
gV
Nuclear O+ → O+ Decays,
CKM Unitarity
gA
g  3g
2
A
???
2
V
Neutron Lifetime
gV
D. Hertzog
22
A consistent picture
J.S. Nico 2014
Unitarity tested
J.S. Nico 2014
Coming Attractions:
• neutrons
• 6He
• neutrino mass
Nab spectrometer: Ee in Si detectors, Pp
from time of flight – measure a, b.
S. Baesseler et al. (2013)
Gravity Magnetism
A nearly perfect neutron trap!
Static field coils
UCN trap door
Vanadium sheet
absorber
Halbach array of
NdFeB permanent
magnets
C.-Y. Liu. S3 2
D.J. Salvat et al. 1310.5759v3
27
Modern 6He work to
measure a, b, uses traps to
localize decays. Intense
6He source needed.
O. Naviliat-Cuncic. S3 3
A. Garcia (2014)
CENPA : world’s largest production
F. Wauters et al. PRC 89, 025501
6He’s
per sec
1011
1010
109
108
Experiments at:
• GANIL
• MSU
• CENPA-UW
• Weizmann
What is the neutrino
mass scale?
Particle Physics
Cosmology
NEUTRINO MASS FROM BETA
SPECTRA
With flavor mixing:
mixing
from oscillations
neutrino masses
mass scale
30
At Karlsruhe Institute of Technology
unique facility for closed T2 cycle:
Tritium Laboratory Karlsruhe
KATRIN
TLK
A direct, modelindependent, kinematic
method, based on β decay
of tritium.
~ 75 m long with 40 s.c. solenoids
31
MASS
RANGE
ACCESSIBLE
KATRIN
starting
2016
Present
Lab Limit
1.8 eV
32
THE LAST ORDER OF
MAGNITUDE
If the mass is below 0.2 eV, how can we measure it?
KATRIN may be the largest such experiment possible.
σ(mv)2 ~
0.38 eV2
Size of experiment now:
Diameter 10 m.
Next diameter: 300 m!
Source T2 column
density near max
Rovibrational
states of THe+,
HHe+ molecule
CYCLOTRON RADIATION
FROM TRITIUM BETA DECAY
(B. Monreal and J.
Formaggio, PRD
80:051301, 2009)
Radiated power ~ 1 fW
25.5-GHz waveguide cell
Working on the UW prototype
PROJECT 8 SENSITIVITY
and OPTIMISTIC
35
MASS
RANGE
ACCESSIBLE
KATRIN
starting
2016
Present
Lab Limit
1.8 eV
36
NEUTRINO MASS LIMITS FROM BETA DECAY
37
NEUTRINO MASS: SOME MILESTONES
Construction
Running
KATRIN:
Project 8:
Proof concept
2013
Prototype
2014
2015
Phase I
2016
2017
2018
2019
38
BETA DECAY, THE METRONOME FOR
ELEMENT MAKING
NRC Decadal Survey (2013)
With the FRIB facility now under construction, we will be able to explore
almost the full span of r-process nuclei, and finally come to an
understanding of how the elements that Chadwick studied were made. 39
40
Battye and Moss, PRL 112,
051303 (2014)
Lensing power spectrum
 Planck
 SPT
Some tensions in ΛCDM
resolved with neutrino
mass:
Shear
correlation
spectrum
 CFHTLenS
41
LEPTONS
TeV
QUARKS
t
τ
GeV
c
μ
MeV
s
d
u
e
keV
eV
νh
meV
νm
νl
??
b
What do we WANT to know?
Quark-lepton effective Lagrangian:
Awful. 10 real couplings, 9 phases. But…
eL,R,S,P,T = 0 if no RH neutrinos
eP = eP = 0
for nuclear decays at low energy
gA ® gA [1- 2 Re(eR )]
Naviliat-Cuncic & Gonzalez-Alonso, Ann. Phys. 525, 600 (2013)
Tensor
Axial vector
Allen, Burman, Hermannsfelt, Staehelin & Braid (1959):
Measure recoil spectrum directly for 6He, 19Ne, 23Ne, 35Ar.
This provided strong confirmation of the V-A picture.
44
Johnson, Pleasonton &
Carlson (1963): Measure
recoil spectrum directly.
α = -0.3343(30).
Tensor < 0.4% (they never
mention Rustad and Ruby!)
This provided strong confirmation of the V-A picture, and the
precision remains unmatched.
45
Mass and mixing parameters
Oscillation
m212
7.54+0.21-0.21 x 10-5 eV2
m322|
2.42+0.12-0.11 x 10-3 eV2
mi
> 0.055 eV (90% CL)
12
34.1+0.9-0.9 deg
23
39.2+1.8-1.8 deg
13
9.1+0.6-0.7 deg
sin213
0.025+.003-.003
Kinematic
< 5.4 eV (95% CL)*
Marginalized 1-D 1- uncertainties.
*C. Kraus et al., Eur. Phys. J. C40, 447 (2005); V. Aseev et al. PRD in press.
46
Other refs, see Fogli et al. 1205.5254
Current status of direct mass measurement
Mainz: solid T2, MAC-E filter
C. Kraus et al., Eur. Phys. J. C40, 447 (2005)
Troitsk: gaseousT2, MAC-E filter
V. Aseev et al., PRD in press (2011)
Together:…
mv < 1.8 eV
(95% CL)
47
KATRIN’s uncertainty budget
σ(mv2) 0
0.01 eV2
Statistical
Final-state spectrum
T- ions in T2 gas
Unfolding energy loss
Column density
Background slope
HV variation
Potential variation in source
B-field variation in source
Elastic scattering in T2 gas
σ(mv2)total= 0.025 eV2
mv< 0.2 eV (90 % CL)
48
A window to work in
Molecular Excitations
49
Microcalorimeters for 187Re ß-decay
MIBETA: Kurie plot of 6.2 ×106 187Re ß-decay events (E > 700 eV)
MANU2 (Genoa)
metallic Rhenium
m(n) < 26 eV
Nucl. Phys. B (Proc.Suppl.) 91 (2001) 293
10 crystals:
8751 hours x mg (AgReO4)
MIBETA (Milano)
AgReO4
m(n) < 15 eV
Nucl. Instr. Meth. 125 (2004) 125
E0 = (2465.3 ± 0.5stat ± 1.6syst) eV
mn2 = (-112 ± 207 ± 90) eV2
MARE (Milano, Como,
Genoa, Trento, US, D)
Phase I : m(n) < 2.5 eV
hep-ex/0509038
50
Electron Capture Holmium Expt (ECHO)
187
51
J.F. Wilkerson
SIGNAL IS A RISING “CHIRP” IN
FREQUENCY
PROJECT 8: A PHASED APPROACH
2007 picture: Lifetime and Correlations combine in a
confused picture for the physics of gA or unitarity
Newer
Measurements
PDG
2006
gA
Newer
Measurements
J. Nico, 2007
Not
consistent
Status of l
Uncertainties dominated by A
c2=15.4/4
D. Hertzog 2013
A Magneto-Gravitational Trap for UCN
• Avoid material loss (magnetic trap): Halbach array of
permanent magnets along trap floor repels spin polarized
neutrons.
• Minimize UCN spin-depolarization loss: EM Coils
arranged on the toroidal axis generates holding B field
throughout the trap (perpendicular to the Halbach array
field).
C.-Y. Liu
D.J. Salvat et al. 1310.5759v3