Neutron EDM

• Past, Present & Future of neutron EDM

B. FilipponeSymmetry Tests in Nuclei & AtomsKITP 9/20/2016

Neutron EDM & New Physics• Small EDM in standard model provides

negligible “background” signal

• New CP violation “natural” in new physics

2

cm-e 103cm-e 10

26exp

31

−

−

⋅<

<

n

SMn

dd

e.g. dn ~ 10-25 e-cm x sinϕCP(1 TeV/MBSM)2

But … Theory Remains Essential• How to interpret measured EDM in terms of new

physics/elementary EDMs– Extraction from p, n, atom EDMs

• E.g. Lattice QCD (This workshop & program!)• Calculation of enhancement factors for certain species

– Model constraints based on EDM limits/observations– Identify source of EDM

3

Searching for a Neutron EDM

• E.M. Purcell and N.F. Ramsey, Phys. Rev. 78, 807 (1950) – Looking for Parity Violation in Neutron Scattering– Pioneered Neutron Beam Magnetic Resonance

E. M. Purcell N. F. Ramsey

5

Moore’s Law for Neutron EDM Searches

6

Simplified Measurement of EDM

B-field

E-field

hEdB

⋅±⋅=

22µν

7

“…always measure a frequency” How to measure a small

frequency?• Ramsey Separated

Oscillatory Fields (SOF)

How to measure a small frequency?• Observation of free

precession

t (sec)

dN/d

t(H

z)

Measure n + 3He capture vs. time with σ>>σ

What is the precision for an EDM measurement?

md TEE

t

||2~

||2~

~

2

E

E

E

∆

∆∆

⋅==

σ

ω

Ed

Sensitivity: E – Electric FieldTm – Time for single measurementm – total # of measurementsN – Total # of counts/meas.mNT|E|2

σm

totd

~

Precise energy measurement requires long coherence/measurement time, giving

Plus shot noise = counting statisticsN1

∝

||2~

EdE∆σUncertainty in d:

8

Coherence time

Best Present Limit on nEDM

9

EDM @ ILL

N (detected n/cycle) 1.3 x 104

|E| 10 kV/cm

Tm 130 s

m (cycles/day) 270

σd (e-cm)/day 3 x 10-25

Baker et al. Phys. Rev. Lett. 97, 131801 (2006)Pendlebury et al. Phys. Rev. D 92, 9092003 (2015)

dn < 3.0 x 10-26 e-cm @ 90% Confidence Limit

mNT|E|2σ

m

totd

~

Ramsey SOF & trapped Ultra-Cold Neutrons from ILL Reactor

Neutron EDM Experiments Worldwide

10

SNS

J-PARC

ILL

PSI

FRMIITRIUMF

RCNP

PNPI

LANL

Experiment UCN source cell Measurementtechniques

σd Goal(10-28 e-cm)

ILL - CryoEDM Superfluid 4He 4He Cryo HV, SuperCond., Ramsey technique, external SQUID mag.

< 5

ILL-PNPI ILL turbinePNPI/Solid D2

Vac. Ramsey technique for ωE=0 cell for magnetometer

Phase1

LANL nEDM

12Slide thanks to T. Ito

Based on LANL UCN Source in Area B

13Slide thanks to T. Ito

14Slides thanks to T. Ito

UltracoldNeutronsat TRIUMF

T. Adachi1, E. Altiere2, T. Andalib3,4, C. Bidinosti3,8, J. Birchall4, M. Chin5, C. Davis5,F. Doresty4, M. Gericke4, S. Hansen-Romu3,4, K. Hatanaka6, T. Hayamizu2, B.

Jamieson3, S. Jeong1, D. Jones2, K. Katsika5, S. Kawasaki1, T Kikawa5,6,1, A. Konaka5,8, E. Korkmaz7 , M. Lang3, T.

Lindner5, L. Lee4,5, K. Madison2, J. Mammei4, R. Mammei3, J.W. Martin3, Y. Masuda1, R. Matsumiya6,

K. Matsuta8, M. Mihara8, E. Miller2, T. Momose2, S. Page4, R. Picker5, E. Pierre6,5, W.D. Ramsay5, L.

Rebenitsch3,4, J. Sonier9, I. Tanihata6, W.T.H. van Oers4,5, Y. Watanabe1, and J. Weinands2

1KEK, Tsukuba, Ibaraki, Japan2The University of British Columbia, Vancouver, BC, Canada

3The University of Winnipeg, Winnipeg, MB, Canada4The University of Manitoba, Winnipeg, MB, Canada

5TRIUMF, Vancouver, BC, Canada6RCNP, Osaka, Japan (Osaka University, Osaka, Japan)

7The University of Northern BC, Prince George, BC, Canada8Osaka University, Osaka, Japan

9Simon Fraser University, Burnaby, BC, Canada

Slide thanks to J. Martin

TRIUMF

Slide thanks to J. Martin

“Phase 1” – what will exist in 2017• use existing EDM Ramsey apparatus from RCNP, Osaka• exploit higher UCN density at TRIUMF (also more beamtime available)• room temperature, 1 small cell, vertical loading, spherical B0 coil• small incremental improvements until replaced by Phase 2

• Active magnetic compensation system• high voltage• comagnetometer• high-flux detector

Slide thanks to J. Martin

“Phase 2” – to implement by 2020

• LD2 moderator, to increase cold flux entering the superfluid• New high-quality guides.• World-competitive nEDM experiment apparatus

CFI Innovation Fund application in progress, in Canada. Scale $16M.

Phase 2 sensitivityδdn ~ 10-27e-cm

R&D on Hg and Xe co-magnetometers is underway

Slide thanks to J. Martin

TUM nEDM@PTB BerlinM. Burghoff, A. Schnabel, J. Voigt @Forschungneutronenquelle Heinz Meier-LeibnitzA. Frei, T. Lauer, P. Link, A. Pichlmaier, T. Zechlau@Technische Universität MünchenI. Altarev, V. Andreev, S. Chesnevskaya, M. Daimer, W. Feldmeier, P. Fierlinger, E. Gutsmiedl, F. Kaspar, F. Kuchler, T. Lins, M. Marino, J. McAndrew, B. Niessen, S. Paul, G. Petzoldt, J. Rothe, C. Schneider, R. Schönberger, S. Seidel, R. Stoepler, T. Stolz, S. Stuiber, M. Sturm, B. Taubenheim, R. Thiele, J. Weber, D. Wurm, @University of California at BerkeleyD. Budker, B. Patton @University of Illinois at Urbana-ChampaignD. H. Beck, S. Sharma @University of MichiganT. Chupp, S. Degenkolb

19Slide thanks to P. Fierlinger

Optimistic (but in principle possible) plan towards a physics result

Options (i) Assembly of Inner and Outer shield with RT chamber(ii) Cryogenic chambers with Inner Shield (iii) Cryogenic chambers with Outer and Inner Shield (before ~ 2022 no UCN at FRM-II EDM position)

Outer Shield at TUMOuter magnetic shield

External field compensation

HV R&D and assembly

Installation at new Super-SUN Stage 1 w/o magnet (2017+), no co-magnetometerBest possible results ~ 3.10-27 ecm (stat, 1

σ)

Magnetometer developmentMagnetometer comparisonsSpin-clocks with polarized

noble gasesComponent optimizationEDM runs at Super-SUN Stage 2 with

magnet (2019+) Best possible result ~ 8.10-28 ecm (stat, 1

σ)

Development of cryogenic chambers

Move Inner Shield to ILL (2016)Adapt/build new UCN components, mobile Cs

magnetometersNo RF shield, only manual alignment control

P. Fierlinger – MSU 4/6/2016 Slide thanks to P. Fierlinger

Sensitivitypotential of nEDMat Super-SUN at

ILL

P. Fierlinger – MSU 4/6/2016Slide thanks to P. Fierlinger

The next version: Super-SUN (funded + under construction at ILL)

P. Fierlinger – MSU 4/6/2016

STAGE 2STAGE 1

Slide thanks to P. Fierlinger

23Slides thanks to K. Kirch

24

Slide thanks to K. Kirch

—25—

nEDM

@PSI-O

verview

• Two UCN precession chambers with opposite electric field directions

• Improved magnetometry Hg – laser read out of Hg-FID to avoid light shiftCs – vectorial3He – free from geometrical phase shift

Status/Prospects:

• Taking data atδdn ~ 1x10-26 e-cm/yr

• n2EDM hopes to reachδdn ~ 4 x10-27 e-cm/yr

nEDM Experiment at Oak Ridge Spallation Neutron

Source - SNS

• High trapped neutron densities – Cold neutrons from spallation source cooled to “Ultra-cold” neutrons via phonon scattering in superfluid He

• LHe as a high voltage insulator– high electric fields

• Use of a 3He co-magnetometer and superconducting shield– Control and measure magnetic field systematics

• Precession frequency measurement via two techniques:• free precession • “dressed spin” techniques

• Sensitivity reach: dn ~ 2 x 10–28 e-cm (in 3 calendar yrs)

Concept: R. Golub & S. K. Lamoreaux, Phys. Rep. 237, 1 (1994)

“Most ambitious nEDMexperiment that is currently underway”

SNS Target Station

27

3He ATOMIC BEAM SOURCE

3He DILUTION REFRIGERATOR

CENTRAL DETECTOR

SYSTEM

MAGNETIC SHIELD HOUSE

Neutron beam is into page

SNS-nEDM Experiment

28

R. Alarcon, R. DipertArizona State University

G. SeidelBrown University

D. BudkerUC Berkeley

M. Blatnik, R. Carr, B. Filippone, C. Osthelder, S. Slutsky, X. Sun, C. Swank

California Institute of Technology

C. Crawford, T. Gorringe, W. Korsch, E. Martin, N. Nouri, B. Plaster

University of KentuckyS. Clayton, S. Currie, T. Ito, Y, Kim, M. Makela, J. Ramsey,

W.Sondheim. Z, Tang, W. WeiLos Alamos National Lab

K. Dow, D. Hasell, E. Ihloff, J. Kelsey, J. Maxwell, R. Milner, R. Redwine, E. Tsentalovich, C. Vidal

Massachusetts Institute of TechnologyD. Dutta, E. Leggett

Mississippi State UniversityR. Golub, C. Gould, D. Haase, A. Hawari, P. Huffman, E.

Korobkina, K. Leung, A. Reid, A. YoungNorth Carolina State University

R. Allen, V. Cianciolo, Y. Efremenko, P. Mueller, S. Penttila, W. Yao

Oak Ridge National LabM. Hayden

Simon Fraser UniversityG. Greene, N. Fomin

University of TennesseeS. Stanislaus

Valparaiso UniversityS. Baeβler

University of VirginiaS. Lamoreaux

Yale University

29Project Manager: V. CiancioloSpokesperson: BWF

M. Ahmed, M. Busch, P. –H. Chu, H. GaoDuke University

I. SilveraHarvard University

M. Karcz, C.-Y. Liu, J. Long, H.O. Meyer, M. Snow

Indiana UniversityL. Bartoszek, D. Beck, C. Daurer, J.-C. Peng,

T. Rao, S. Williamson, L. YangUniversity of Illinois Urbana-Champaign

Technical Challenges for nEDM@SNS• 1200 L of superfluid Helium @ T = 0.5K

– Must minimize heat sources• Eddy-current heating from AC B-fields minimal conducting material

– Large cooling plant required

• Highly sensitive to magnetic field variations and gradients– Significant magnetic shielding required– B-field uniformity of ppm/cm over measurement volume– Low-field operation: B = 3 µT

• High electric fields: E = 75 kV/cm– Producing and maintaining V > 600 kV in cryogenic environment

30

New High Voltage Concept

31Previous concept – charging capacitor

Cel

l #1

Cel

l #2

100 kV10

0 kV

600

kV

Cel

l #1

Cel

l #2

0 kV

-50 kV

+++++++Very large diameter variable capacitor (>1m) with small gap (

Status of the nEDM@SNSExperiment

• Demonstration of Critical Components is Underway (2014-2017)– Construction of most technically challenging pieces:

• HV @ LANL and light detection system @ ORNL• Polarized 3He system @ Illinois• Magnet system @ Caltech • Polarized UCN & 3He test bed at NCSU PULSTAR reactor

• Large Subsystem Integration and Acquisition of Critical Components (2018-2020)– Begin commissioning components at Oak Ridge

National Laboratory in 2019

Farther Future nEDM

• Systematics can produce “surprises”, but if these are controlled then sensitivity is limited by counting statistics need more neutrons– 2nd Target station at SNS could give ~ 25x more cold neutrons– ESS (European Spallation Source) also promises high flux of cold

neutrons for high density UCN• Cryogenic experiment being discussed

33

Summary• A number of novel technologies are being developed

to extend neutron EDM sensitivities by two orders-of-magnitude

• Anticipate:– A new best sensitivity within 1-2 year– Factor of 10 improvement within 3-4 yrs– Factor of 100 improvement within 7-9 yrs– TBD > 10 years

34

Extra Slides

35

New External Building will House the Experiment

36

T/CP Violation

37

EdBH

⋅+⋅= µP-evenT-even

P-oddT-odd

Non-zero d violates T and CP (via CPT)

JJ and

JJWith

dd == µµ

-+B-+J

+-E-+d-+µTP

How to measure an EDM?

BS if ; BSμ2 BμdtSdτ

21 spinfor ; Sμ2μ ;BμH

N

N

⊥

⇒×==

=⋅=ˆ

Classical Picture:• If the spin is not aligned with B there will be a precession

due to the torque • Precession frequency given by

Recall magnetic moment in B field:

fS

iS

Sd

ϕdEin d afor E2d

B B2μ dtdS

S1

dtdω

NN

N

or

γϕ ====

ω Gyromagnetic Ratio

But NH3 EDM is not T-odd

But some molecules have HUGE EDMs!H20: d = 0.4 x 10-8 e-cmNaCl: d= 1.8 x 10-8 e-cmNH3: d = 0.3 x 10-8 e-cm

−=+=

≠

exist! JJdd and

JJdd both

JJdd

If neutron/electron had a degenerate state, then their EDM would not violate T or CP. But they don’t!

Ground state is actually asuperposition

J

J

39

Neutron EDMNeutron EDM & New PhysicsBut … Theory Remains EssentialSearching for a Neutron EDMSlide Number 5Moore’s Law for Neutron EDM SearchesSimplified Measurement of EDMWhat is the precision for an EDM measurement?Best Present Limit on nEDMNeutron EDM Experiments Worldwide Neutron EDM Searches LANL nEDMBased on LANL UCN Source in Area BSlide Number 14Ultracold Neutrons at TRIUMFTRIUMF Slide Number 17Slide Number 18TUM nEDMOptimistic (but in principle possible) plan towards a physics resultSensitivity potential of nEDM �at Super-SUN at ILLThe next version: Super-SUN (funded + under construction at ILL)Slide Number 23Slide Number 24Slide Number 25 nEDM Experiment at �Oak Ridge Spallation Neutron Source - SNSSNS Target StationSNS-nEDM ExperimentSlide Number 29Technical Challenges for nEDM@SNSNew High Voltage ConceptStatus of the nEDM@SNS ExperimentFarther Future nEDMSummaryExtra SlidesNew External Building will House the Experiment T/CP ViolationHow to measure an EDM?But some molecules have HUGE EDMs!