frpnc @ triumf atomic parity violation in francium seth aubin college of william and mary panic 2011...
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FrPNC @ TRIUMF
Atomic Parity Violation in Francium
Seth Aubin
College of William and Mary
PANIC 2011 Conference, MIT
FrPNC collaborationS. Aubin (College of William and Mary)
J. A. Behr, K. P. Jackson, M. R. Pearson (TRIUMF)
V. V. Flambaum (U. of New South Wales, Australia)
E. Gomez (U. Autonoma de San Luis Potosi, Mexico)
G. Gwinner, R. Collister (U. of Manitoba)
D. Melconian (Texas A&M)
L. A. Orozco, J. Zhang (U. of Maryland at College Park)
G. D. Sprouse (SUNY Stony Brook)
Y. Zhao (Shanxi U., China)
Funding
Atomic Parity Violation: Basic Processes
e- e-
N N
e- e-
N N
Z0
e- e-
N N
W,Z0 exchange in nucleus
Standard Electromagnetic
Interaction
(parity conserving)
Z0 exchange
Electron-Nucleon PNC
(nuclear spin-independent)
Intra-nuclear PNC
Anapole moment
(nuclear spin-dependent)
Atomic Parity Violation: Basic Processes
e- e-
N N
e- e-
N N
Z0
e- e-
N N
W,Z0 exchange in nucleus
Standard Electromagnetic
Interaction
(parity conserving)
Z0 exchange
Electron-Nucleon PNC
(nuclear spin-independent)
Intra-nuclear PNC
Anapole moment
(nuclear spin-dependent)
PNCPNC
Motivation 1:Nuclear Spin-Independent PNC
e- e-
N N
Z0
Z0 exchange
Electron-Nucleon PNC
(nuclear spin-independent)
)(2
51, rG
H nsiPNC
The Hamiltonian for this interaction:(infinitely heavy nucleon approximation)
G = Fermi constant = 10-5/mp2
Proton:
Neutron:
04.0sin41 221
,1 Wp 5.0,1 n
Ae
VN
[Standard Model values for 1, (p,n)]
Motivation 1:Nuclear Spin-Independent PNC
Z0 exchangeElectron-Nucleons PNC
(nuclear spin-independent)
For a nucleus with Z protons and N neutrons:
)(22
5, rQG
H weaknsiPNC
Qweak = weak charge of nucleus -N
= 2(1,p Z + 1,n N)
e- e-
nucleons
Z0
Ae
VN
nucleons
ondistributinucleon )( r
Motivation 1:Testing and Probing the Weak Interaction
Parity Violation = Unique Probe of Weak Interaction
Atomic PNC (APV) experiments test and constrain the Standard Model
Motivation 1:Testing and Probing the Weak Interaction
Parity Violation = Unique Probe of Weak Interaction
Atomic PNC (APV) experiments test and constrain the Standard Model
[figure from Young et al., Phys. Rev. Lett. 99, 122003 (2007)]
Effective e--quark couplings C1u & C1d
[figure by G. Gwinner, adapted from Erler et al. Phys. Rev. D 72, 073003 (2005)]
Weak mixing angle
Atomic PNC
OddParity )(22
5, rQG
H weaknsiPNC
Electron wavefunction does not have a definite parity !!!
SP P
PS S
PNC
PNC
Parity forbidden transitions become possible (slightly) !!!
(Cs) 10~ 113,
RZnsiPNC
relativistic enhancement factor
Cs
Fr
nsiPNC
nsiPNC
,
,
18
Francium advantage:
Motivation 2:Nuclear Spin-Dependent PNC
e- e-
N N
W,Z0 exchange in nucleus
Intra-nuclear PNC
Anapole moment
Hyperfine Interaction+
NSI - Z0 exchange(nuclear spin-dependent)
e- e-
N N
Z0
Z0 exchangeElectron-Nucleon PNC
(vector) (axial)
Ve
AN
e- e-
N N
Z0
Ae
VN
What’s an Anapole Moment ?e- e-
N N
W,Z0 exchange in nucleus
e- e-
N N
W,Z0 exchange in nucleus
Answer:Electromagnetic moment produced by a toroidal current.
Time-reversal conserving.
PNC toroidal current.
Localized moment, contact interaction.
[A. Weis, U. Fribourg (2003)]
Motivation 2:Nuclear Anapole Moment
e- e-
N N
W,Z0 exchange in nucleus
Anapole moment
)()12
),(, rIII
KGH npanapolensdPNC
For heavy atoms, the anapole moment term dominates.
Motivation 2:Nuclear Anapole Moment
e- e-
N N
W,Z0 exchange in nucleus
Anapole moment
)()12
),(, rIII
KGH npanapolensdPNC
For heavy atoms, the anapole moment term dominates.
momentumangular
orbitalnucleonvalencel
spinnuclearI
IK lI
12/1 2/1
3/2
0
,,),( ~10
9NZ
rmg
p
npnpnpanapole
radiusnucleonr
momentmagneticnucleon
fm2.1~
137/1
0
Motivation 2:Nuclear Anapole Moment
e- e-
N N
W,Z0 exchange in nucleus
Anapole moment
)()12
),(, rIII
KGH npanapolensdPNC
For heavy atoms, the anapole moment term dominates.
momentumangular
orbitalnucleonvalencel
spinnuclearI
IK lI
12/1 2/1
3/2
0
,,),( ~10
9NZ
rmg
p
npnpnpanapole
radiusnucleonr
momentmagneticnucleon
fm2.1~
137/1
0
10.2 and 4~ np gg characterize
the nucleon-nucleus weak potential.
Motivation 2:Isovector & Isoscalar Nucleon Couplings
Cs anapole (Boulder) and low-energy nuclear PNC measurements produce conflicting constraints on weak meson-nucleon couplings.(Desplanques, Donoghue, and Holstein model)
[Haxton et al., Phys. Rev. C 65, 045502 (2002) and 6Li(n,) from Vesna Phys. Rev. C 77, 035501 (2008)]
Need to understand nuclear structure better.
Measure anapole in a string of Fr isotopes
Motivation 2:Isovector & Isoscalar Nucleon Couplings
[Behr and Gwinner, J. Phys. G 36, 033101 (2009)]
Francium isotopes provide orthogonal
constraints !!!
Cs
Fr
anapolePNC
anapolePNC
,
,
11
Francium advantage:
Cs
Fr
anapolePNC
anapolePNC
,
,
11 Cs
Fr
anapolePNC
anapolePNC
,
,
11
Francium advantage:
N=even
N=odd
Cs anapole (Boulder) and low-energy nuclear PNC measurements produce conflicting constraints on weak meson-nucleon couplings.(Desplanques, Donoghue, and Holstein model)
[Haxton et al., Phys. Rev. C 65, 045502 (2002) and 6Li(n,) from Vesna Phys. Rev. C 77, 035501 (2008)]
FrPNC program:Atomic PNC Experiments in Francium
Fr is the heaviest of the simple (alkali atoms). Electronic structure is well understood. Particle/nuclear physics can be reliably extracted.
Fr has large (relatively) PNC mixing. PNC ~ 10-10 is still really really small … we’re going to need a lot of Fr.
Fr does not exist sufficiently in nature.
+ dipole
trap
Atomic PNC in Fr (NSI)
F’
F
F’
F
7S1/2
8S1/2
7P3/2
7P1/2506 nmE1
“forbidden”
F’
F
F’
F
7S1/2
8S1/2
7P3/2
7P1/2506 nmE1
“forbidden”
Excitation to continuum(ionization)
506 nm
506 nm
718 nm817 nm
1.3 m1.7 m
Fr atoms(trapped)
k
EStark
BDC
StarkDCPNC EkB
2*2
2
Re2 PNCPNCStarkStark
PNCStark
AAAA
AARateTransition
Amplification by Stark Interference
Statistical Sensitivity:
M1 is strongly suppressed.
Anapole Moment in Fr
New Method: Anapole can be measured by driving a parity forbidden E1 transition between two hyperfine states with F=1, mF=1.
/2 pulse preparation: the atoms are prepared in a 50/50 superposition of the initial and final states (equivalent to interference amplification) before application of the microwave driving E-field.
FmF ,
',' FmF
2/17S E1PNCM1
Anapole Moment in Fr
New Method: Anapole can be measured by driving a parity forbidden E1 transition between two hyperfine states with F=1, mF=1.
/2 pulse preparation: the atoms are prepared in a 50/50 superposition of the initial and final states (equivalent to interference amplification) before application of the microwave driving E-field.
FmF ,
',' FmF
2/17S E1PNCM1
microwaveDCanapole EMB
2/1
Anapole Moment in Fr
New Method: Anapole can be measured by driving a parity forbidden E1 transition between two hyperfine states with F=1, mF=1.
/2 pulse preparation: the atoms are prepared in a 50/50 superposition of the initial and final states (equivalent to interference amplification) before application of the microwave driving E-field.
FmF ,
',' FmF
2/17S E1PNCM1
for Emicrowave~0.5 kV/cm and 106 atoms.
120~ HznoisetoSignal
[E. Gomez et al., Phys. Rev. A 75, 033418 (2007)]
microwaveDCanapole EMB
2/1
Simulating Fr Anapole with Rb
180 ms coherence time in blue-detuned dipole trap
(/2 pulse with Rb)
phasePNC
PNC
A
ARateTransition
cos4/1
2/12
Simulating the PNC Interference
APNC simulated with 10-4 M1 transition
[Data by D. Sheng (Orozco Group, U. of Maryland)]
FrPNC: Current StatusPresent: Construction of an on-line, shielded laser laboratory at TRIUMF with 100 db RF suppression.
Fall 2011: (14 shifts in December)
Installation of high efficiency MOT (from U. of Maryland).
2012: Physics starts !!!
Hyperfine anomaly (Pearson), 7S-8S M1 (Gwinner), Anapole (Orozco), optical PNC (Gwinner), …
FrPNC collaborationS. Aubin (College of William and Mary)
J. A. Behr, K. P. Jackson, M. R. Pearson (TRIUMF)
V. V. Flambaum (U. of New South Wales, Australia)
E. Gomez (U. Autonoma de San Luis Potosi, Mexico)
G. Gwinner, R. Collister (U. of Manitoba)
D. Melconian (Texas A&M)
L. A. Orozco, J. Zhang (U. of Maryland at College Park)
G. D. Sprouse (SUNY Stony Brook)
Y. Zhao (Shanxi U., China)
Funding