electric dipole moment searches e.a. hinds birmingham 11 th july 2011 centre for cold matter...
DESCRIPTION
P. Harris IoP 2011 Measurement principle BE BB Measure Larmor spin precession freq in parallel & antiparallel B and E fields d makes precession faster... Reverse E relative to B, look for freq shift.... or slower.TRANSCRIPT
Electric dipole moment searches
E.A. Hinds
Birmingham 11th July 2011
Centre for Cold MatterImperial College London
YbF
atom/moleculelevel
EDM: from particles to atoms and molecules
nuclearlevel
NNNN Schiffmoment
mercury
HiggsSUSY
Left/Right
StrongCP
field theoryCP model
qGG
neutron
nucleonlevel
electron/quark level
de
dq
dcq
~
P. HarrisIoP 2011
Measurement principle
B E
mB
Measure Larmor spin precession freq in parallel & antiparallel B and E fields
d makes precessionfaster...
Reverse E relative to B, look for freq shift.... or slower.
Pulsed YbF beam
PumpA-X Q(0) F=1
ProbeA-X Q(0) F=0
PMT
3K beam
F=1
F=0
rf pulse
B HV+
HV-
eEDM in practice (Imperial)Ch 15 Cold Molecules, eds. Krems, Stwalley and Friedrich, (CRC Press 2009)
P. HarrisIoP 2011
nEDM in practice
N S
Magnetic shielding
Storage cell
Magnet & polarizing foil Ultracold
neutrons(UCN)
UCN detector
Approx scale 1 m
Magnetic field coil
B
High voltage lead
E
/analysingfoil
Status of eEDM and nEDM
de = (-2.4 5.7 1.5) ×10-28 e.cm
68% statisticalsystematic - limited by statistical noise
• New eEDM result – YbF – Hudson et al. (Nature 2011)
• Previous eEDM result - Tl atoms de < 2.0 × 10-27 e.cm with 90% confidence
Regan et al. (PRL 2002)Nataraj et al. (PRL 2011)
de < 1 × 10-27 e.cm with 90% confidence dn < 3 × 10-26 e.cm with 90% confidence
Current upper limits
Left -Right MSSM
f ~ a/p
Multi Higgs
MSSM f ~ 1
10-24
10-22
10-26
10-28
10-30
10-32
10-34
10-36
eEDM (e.cm)
Imperial eEDM starting to explore
this region
Standard Model
de < 1.0 x 10-27 e.cm
Imperial eEDM (2011)Excluded region
e.g. Pospelov and RitzarXiv:hep-ph/0504231(2005)
P. HarrisIoP 2011
Constraints on SUSY parameters
Pospelov & Ritz, hep-ph/0504231
MSUSY = 500 GeVtan b = 3
e
P. HarrisIoP 2011
SUSY again Lebedev et al., hep-ph/0402023
n
Tl YbF (2011)n (2006)
Where do we go from here?nEDM Better polarisation
Higher E field Longer spin coherence time More neutrons
10 x betterCryoEDM
eEDM Better field control Longer spin coherence time More YbF molecules
10 x betterCryoYbF
Cryogenic YbF experiment (Imperial)
YbF beam
YAGablationlaser3K He gas cell
Yb+AlF3target
New J. Phys. 11 123026 (2009) Physical Review A (2011)S. M. Skoff et al.
Uses new molecular beam source
eEDM prospects with new source15 more molecules
3 longer interaction time
=> access to few x 10-29 e.cm range
=> 10 better signal:noise ratiowill improve systematics as well as statistics
+-+-
+-
+-
+-
garnet
E+-
squid magnetometer
GGG (LANL), GIG (Amherst)Gadolinium Garnets
Huge number of electrons
Other electron EDM searches+-
+-
+-
+-
+- E+-
Cs atomsFountain (LBL), Trapped (Penn State), Trapped (Texas) Long coherence time
Molecules Large effective E field
PbF beam (Oklahoma) similar to YbFMetastable ThO beam (Yale/Harvard) similar to YbF
Trapped HfF+ ions (JILA) 1 molecule; very long coh.time
none competitive with YbF in the immediate future
P. HarrisIoP 2011
Cryogenic nEDM experiment
• Neutrons produced, transported, & stored. Need lower losses.
• 10 kV/cm applied; aiming for 20-30 kV/cm
• Polarisation observed, but must improve
• Detector efficiency set to improve significantly
• Magnetic field stability to be improved by factor 1000
Sussex, RAL, Oxford, ILL,Kure
P. HarrisIoP 2011
Other nEDM experiments PSI (50 people) aim 5 10-27 by 2015 ORNL (90 people) construction 2017;
aims eventually for 5 10-28
e.cm
ILL: Russian group. Reinstating system from 1990 measurement. Perhaps 1 10-26 e.cm eventually.
FRM, Munich: hoping to install UCN source. Nothing firm yet
Masuda, Japan: observed resonance, but very low stats. Move to TRIUMF?
P. HarrisIoP 2011
... and other particles Muon EDM: from g-2
(7E-19 e.cm; proposed upgrades could reach ~10-24 e.cm by ~2020)
Deuterium EDM: similarprinciple (claimed potential reach ~10-29 e.cm)
Tau weak dipole moment – look for CP-odd observables in diff. x-sec at Z res.(6E-18 e.cm from LEP data)Sensitivity to physics BSM depends on source of CPv
Conclusions
These place strong constraints onCP-violation beyond std model
de < 1 × 10-27
e.cm dn < 3 × 10-26
e.cm
Current upper limits
UK leads the world in both
Will continue to do so if projects funded.