The EDM program in Groningen Rick Bethlem, Anastasia Borschevsky, - - PowerPoint PPT Presentation

The EDM program in Groningen

Van Swinderen Institute for Particle Physics and Gravity, RUG Groningen and LaserLaB Amsterdam, Department of Physics and Astronomy, VU Amsterdam

Rick Bethlem, Anastasia Borschevsky, Klaus Jungmann, Steven Hoekstra, Rob Timmermans, Wim Ubachs, Lorenz Willmann

Main message of this talk:

• 1. Most exciting low-energy particle physics experiment
• 2. Ambitious and realistic plan
• 3. Team with perfect expertise for serious impact

The EDM program in Groningen

Van Swinderen Institute for Particle Physics and Gravity, RUG Groningen and LaserLaB Amsterdam, Department of Physics and Astronomy, VU Amsterdam

Rick Bethlem, Anastasia Borschevsky, Klaus Jungmann, Steven Hoekstra, Rob Timmermans, Wim Ubachs, Lorenz Willmann

The Electric Dipole Moment of the electron (eEDM)

Is the electron round?

an eEDM would violate P and T Symmetry -> violates CP symmetry by CPT theorem E B E B E B T P The Electric Dipole Moment of the electron (eEDM)

Is the electron round?

choice of system interpretation experiment production state preparation interaction detection

repeat

• Place N electrons in parallel E and B fields
• Measure the precession frequency for time
• Reverse relative direction of the fields, measure again
• EDM signature: shift of precession frequency

How to measure an eEDM?

τ

2002: best experimental limit using thallium atoms

10−25 10−26 10−27 10−28 10−29 10−30 10−31 10−32 10−33 10−34 10−39 10−40 de (e cm)

multi- Higgs left right symmetric extended technicolor Standard Model lepton fmavour- changing alignment split SUSY SO(10)GUT seesaw neutrino Yukawa couplings accidental cancellations approx. CP approx. universality exact universality naive SUSY heavy fermions

2011: YbF molecule result (Hinds et al, London) 2014: ThO molecule result (DeMille, Gabrielse, Doyle, Yale/Harvard) HfF+ / ThF+ results from Cornell team (Boulder) in between YbF and ThO results (unpublished) Statistical limit achievable in our proposal

The current experimental eEDM limit constrains SUSY particles up to 3 TeV

Best measurements so far

5 10 15 20 10 20 30

Applied field E (kV/cm) Eeff (GV/cm)

Huge (~106) enhancement effects!

The valence electron is exposed to the internal field of the polarised molecule

Reduced sensitivity (~ 10-10) to magnetic fields perpendicular to E

F=1 F=0

• 1

+1 MF: N=0 J=1/2

no fake-EDM from motion in magnetic field

Particle physics with molecules?

Effective electric field Coherent measurement time Number of detected molecules

We aim for a next- generation eEDM experiment using cold molecules

The best you can do: shot-noise limit on statistical error

σd = ~ e 1 2Eeffτ √ N

Improve on ongoing experiments?

t ~ 1 ms L ~ 0.5 m L

Recent progress in cooling methods allows for new generations of precision measurements Experiments so far have been done in beams: fountain?

t ~ 100 ms L ~ 0.5 m

L

slow vertical beam

trap?

t ~ 1-10 s L ~ 0.5 mm

L

molecules trapped in laser focus

key ingredient: intense, slow and cold beam choice of the system: rotational ground state of BaF (barium-monofluoride) N=0

F=1 F=0 cryogenic source decelerator state preparation interaction detection cooling guide

Best possible combination of interaction time and N

Our approach

cryogenic source decelerator state preparation interaction detection cooling guide

I. Intense: cryogenic source

Supersonic Cryogenic velocity (m/s) 100 200 300 400 500 600

ThO cryogenic source

• Use electrostatic guide to bring molecules to decelerator
• N: ~ 1010 molecules/shot through the guide, based on BaF, YbF, CaH and ThO results
• Long pulse is not an issue in a beam experiment
• 10 Hz operation demonstrated on BaF cryogenic source with moving pill.
• Novel but proven technology

cryogenic source decelerator state preparation interaction detection cooling guide

Existing machine @ VSI, SrF deceleration demonstrated

• II. slow:

the decelerator

cryogenic source decelerator state preparation interaction detection cooling guide

10 12 14 16 18 20 22 24 26 28 30

intensity (arb.units)

10 20 30 40 50 60 70 80 90 100 110 120

arrival time (ms)

22.0 22.5 23.0 23.5

10 20 30 40 50

3 % of the low-field seeking molecules decelerated to 30 m/s

BaF deceleration simulation

• II. slow:

the decelerator

cryogenic source decelerator state preparation interaction detection cooling guide

• III. cold:

laser cooling Transverse laser cooling of BaF: essential to be able to profit from slow beam

X2Σ A2Π1/2

v''=0 v''=1 v''=2 v'=0 v'=1 v'=2 860 nm

0.95 0.048 0.003 0.045 0.871 0.086

896 nm 829 nm 862 nm

Comparable to CaF, SrF, SrF:

• Excited state lifetime ~ 50 ns
• Franck-Condon factors good
• Convenient diode laser wavelengths
• optical molasses laser cooling to 200

microKelvin in 3 - 5 ms initial v| max. 5 m/s final v| ~ 20 cm/s beam expands

Without cooling, density loss would compensate interaction time gain.

key ingredient: intense, slow and cold beam choice of the system: rotational ground state of BaF (barium-monofluoride) N=0

F=1 F=0 cryogenic source decelerator state preparation interaction detection cooling guide

Best possible combination of interaction time and N

Our approach

Lasers, spectroscopy, laser cooling Stark deceleration, molecular beams, laser cooling Molecular structure calculations, beyond the Standard Model Molecular structure and spectroscopy Molecular beams, deceleration, molecular fountain EDMs, precision measurements, magnetic field control EDMs, particle physics theory Steven Hoekstra Rick Bethlem Lorenz Willmann Anastasia Borschevsky Klaus Jungmann Rob Timmermans Wim Ubachs

The EDM team

VSI VU VU VSI VSI VSI VSI

Matching Expertise

EDM program within Nikhef

• This EDM program is the novel, focused contribution of the VSI
• It is complementary to the existing Nikhef portfolio
• We look forward to collaboration opportunities on both physics and

technology!

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