Status of the proton EDM experiment at BNL Yannis K. Semertzidis Brookhaven National Laboratory

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Status of the proton EDM experiment at BNL

Yannis K. SemertzidisBrookhaven National Laboratory

•Motivation•Neutron EDM experiments•Status of Storage Ring EDM experiments (proton & deuteron)•Plan

XXIX Workshop on Recent Advances in Particle Physics and Cosmology

Patrai, 14-16 April 2011

The great mystery in our universe: matter dominance over anti-matter

€

nB

nγ

≈10−10

€

nB

nγ

≈10−18

Observations

From SM (CKM-Weak interactions):

In Quantum Mechanics: a non-degenerate system with Spin is defined by the spin vector

0d

+

-

dd

If the particle has an EDM, its vector needs to be aligned with the spin vector, locked to its direction, i.e. it needs to choose either along or opposite but not both (non-degenerate). “CP-Violation Without Strangeness”, Khriplovich/Lamoreaux.

A Permanent EDM Violates both T & P Symmetries:

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-

+

-

+

-T

P

Yannis Semertzidis, BNL

The Electric Dipole Moment precesses in an Electric field

dsd E

dt

+

-

d The EDM vector d is along the particle spin direction

A charged particle between Electric Field plates would be lost right away.

- +E

+

Measuring an EDM of Neutral ParticlesMeasuring an EDM of Neutral Particles

H = -(d E + μ B) ● I/I

mI = 1/2

mI = -1/2

ω1 ω2d

EB

12 2ω = B dE

1ω

µ d µ

EB

2ω 2 2= B dE

2ω

2=E

( )1d4

ω -ωd = 10-28 e cmE = 200 kV/cm

δ = 10-7 rad/s ~1 turn/year

dsB d E

dt

Spin precession at rest

Compare the Precession Frequencieswith E-field Flipped:

1 2 4dE

+

-

1 1d

EPA N T


Main Systematic Error: particles have non-zero magnetic moments!

•For the nEDM experiments a co-magnetometer or SQUIDS are used to monitor the B-field: cancellation level needed for 10-28e-cm is of order 3pG.

dsB d E

dt


Important Stages in an EDM Experiment

1. Polarize:state preparation, intensity of beams

2. Interact with an E-field:the higher the better

3. Analyze:high efficiency analyzer

4. Scientific Interpretation of Result! Easier for the simpler systems

EDM Experiments

• Statistics is of the essence (number of neutrons, spin coherence time,…)

• Systematics is close second (magnetic fields, geometrical phases,…)


nEDM experiment at ILL (Grenoble):


New UCN experiment at ILL:Expect a factor of ~100 improvement in

sensitivity due to

• Neutrons in 0.5 K

He bath

• ~50 more neutrons

• E-field: 4-6 at cryo temp.

• Longer coherence times

Neutron EDM at PSI

Lower Cryostat

Upper Cryostat

~6 m

DR LHe Volume~450 liters

Upper Cryostat Services

DR Central LHe Volume~400 mK, ~1000 liters

Reentrant Neutron Guide

ABS Line

3He Injection Volume

4-layer-metal shield

3He Injection VolumeCos magnet

ABS

SNS nEDM Experiment - Vertical Section View

• The current value is < 3 x 10-26 e•cm (90% C.L.)

• Hope to obtain roughly < 8 x 10-28 e•cm with UCN in superfluid He


Neutron EDM Timeline

2000 2010 2020

1E-24

1E-26

1E-28

1E-30

1E-32

ED

M L

imits

[ec

m]

ILL, n

PSI, n

SNS, n

Year

Storage Ring EDM experiments(or how to create a Dirac-like particle in an electric storage ring)

A charged particle between Electric Field plates would be lost right away…

- +E

+


…but can be kept in a storage ring for a long time

E

E E

E


The sensitivity to EDM is optimum when the spin vector is kept aligned to the momentum vector

0a

Momentumvector

Spin vector

dsd E

dt

E

E E

E


The spin precession relative to momentum in the plane is kept near zero. A vert. spin precession vs. time is an indication of an EDM (d) signal.

0a dsd E

dt

E

EE

E

Freezing the horizontal spin precession

2

a

e ma E

m p

• The spin precession is zero at “magic” momentum (0.7 GeV/c for protons, 3.1GeV/c for muons,…)

2, with

2

m gp a

a

• The “magic” momentum concept was first used in the last muon g-2 experiment at CERN and BNL.


When P=Pmagic the spin follows the momentum

0a

dsd E

dt

E

E E

E

No matter what the E-field value is the spin follows the momentum vector creating an ideal Dirac-like particle (g=2)

1. Eliminates geometrical phase effect2. Equalizes the beta-functions of counter-rotating (CR)

beams3. Closed orbits of the CR beams are the same

There is an asymmetry between E and B-fields and g-2 precession

• B-fields:

Independent of velocity!

• E-fields:

Depends on velocity

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r a =e

ma

r B

2

a

e ma E

m p

Freezing the horizontal spin precession for the proton a=1.79,

and deuteron a=-0.1432

a

e ma E

m p

• For particles with negative anomalous magnetic moment there is no …magic.

• A dipole B-field is required to cancel the g-2 precession in the deuteron case

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r a =e

ma

r B + a −

m

p

⎛

⎝ ⎜

⎞

⎠ ⎟

2 ⎡

⎣ ⎢ ⎢

⎤

⎦ ⎥ ⎥

r β ×

r E

⎧ ⎨ ⎪

⎩ ⎪

⎫ ⎬ ⎪

⎭ ⎪

Storage Ring EDM experiments:

1. High beam intensities (1010-1011), with high polarization (>0.8), and low emittance are currently available

2. Large electric fields are possible (10-20MV/m)

3. Spin coherence time ~103s are possible

4. High efficiency, large analyzing power (~0.5) polarimeters are available for the proton and deuteron at ~1 GeV/c momentum making possible the next sensitivity level

5. Direct access to charged particle EDMs

extraction adding white noise to slowly increase the beam phase space

“defining aperture”polarimeter target

RL

RLH

UD

UDV

carries EDM signalincreases slowly with time

carries in-plane precession signal

pEDM polarimeter principle: probing the proton spin components as a function of storage time

Micro-Megas TPC detectorand/or MRPC

Micro-Megas TPC tests at Saclay by the Demokritos group G. Fanourakis, et al.

Micro-Megas based polarimeter

• Pointing capability

• High rate operation

• MM-TPC (Demokritos)

• MM-Telescope (Demokritos)

• Electronics/DAQ:

• Univ. of Patras

• Univ. of Thessaloniki

Proton at its magic momentum• We had two successful technical reviews

1.December 2009, with a subsequent scientific approval at BNL.

2.March 2011

• Both reviews are strongly encouraging the collaboration to pursuit the method due to its great physics reach.

• No surprises, no show-stoppers, several great suggestions

• We are preparing a proposal to DOE to be submitted within the next two months

Rough cost range (contingency of 50-100% is included)

• Experiment (~$40M)

• Ring construction (~$18M) (new construction)

• Beamline (~$12M)

• R&D: two years

• Requested funding for R&D: $3M

Novelty• The largest radius electric ring in the world:

~30-40m

• Proton (magic) kinetic energy: 233 MeV

• Proton (magic) momentum: 0.7 GeV/c

• Magic: In an electric ring, the proton spin precesses exactly as much as the momentum. Protons behave as ideal Dirac-like particles…

Challenges

• The largest electric ring in the world

• Reduce low frequency B-field noise by a factor of 3×108 with passive (105) and an active feedback (3×103)

• The storage ring is the experiment

Running time plan• 1st year running for systematics and sensitivity

goal: 10-28ecm

• Additional 3 years for better than 10-29ecm statistical sensitivity

• Required beam: 2×1010 polarized protons in each direction (electric ring) with small emittances. Beam parameters are already available at BNL.

Main Motivation• CP-violation beyond the SM (300-3000TeV),

beyond the LHC design sensitivity

• CP-violation in SM: θQCD < 0.3×10-13

• If found, it can help resolve the matter-antimatter asymmetry mystery of our universe

• At least ten times the best planned neutron EDM sensitivity

• It can resolve SM vs. non-SM CP-V source

Further prospects• Deuteron (requires combination of E- and B-

fields)

• 3He

• …

• The proton at its magic is the simplest of all

• They all probe different CP-violating sources

EDMs of hadronic systems are mainly sensitive to

• Theta-QCD (part of the SM)

• CP-violation sources beyond the SM

A number of alternative simple systems could provide invaluable complementary information (e.g. neutron, proton, deuteron,…).

Two different labs to host the S.R. EDM experiments

• BNL, USA:

proton “magic” ring

• COSY/IKP, Germany: deuteron ring

Booster

AGS

Technically driven pEDM timeline

• Two years R&D

• One year final ring design

• Two years ring/beamline construction

• Two years installation

11 12 13 14 15 16 17 18 19 20

Electrow

eakB

aryogenises

GU

T S

US

Y

J.M.Pendlebury and E.A. Hinds, NIMA 440 (2000) 471e-cm

Gray: NeutronRed: Electron

n current

n target

Sensitivity to Rule on Several New Models

e current

e targetp, d target

Physics reach of magic pEDM (Marciano)

The proton EDM at 10-29e∙cm has a reach of >300TeV or, if new physics exists at the LHC scale, δ<10-7-10-5 rad CP-violating phase; an unprecedented sensitivity level.

The deuteron EDM sensitivity is similar.

• Sensitivity to SUSY-type new Physics:

• Sensitivity to new contact interaction: 3000 TeV

10 13 Currently: 10 , Sensitivity with pEDM: 0.3 10

€

pEDM ≈10−24 e⋅ cm × sinδ ×1TeV

MSUSY

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⎝ ⎜

⎞

⎠ ⎟

2

SummaryPhysics is a must do, positive or negative result

can differentiate between models (BAU)E-field issues understood wellWorking EDM lattice with long SCT and large

enough acceptance (1.3×10-29ecm/year)We plan to demonstrate feasibility of BPM

assumptions including tests at RHIC

We are submitting the proposal to DOE within the next two months.

Magnetic shielding(active + passive: 3×108)

4 layers of 0.062" thick Amumetal with 3" spacing between layers: SF 133K:1 OD 35”

Quotation from Amuneal to produce 4 layers ofclam shells (legos) ready to be installed.

The EDM signal: early to late change• Comparing the (left-right)/(left+right) counts vs.

time we monitor the vertical component of spin

(L-R)/(L+R) vs. Time [s]

M.C. data

After the review committee

suggestion (T. Roser) : Take more beam

very early and late

(L-R)/(L+R) vs. Time [s]

M.C. data

Physics strength comparison (Marciano)

System Current limit [ecm]

Future goal Neutron equivalent

Neutron <1.6×10-26 ~10-28 10-28

199Hg atom <3×10-29 <10-29 10-25-10-26

129Xe atom <6×10-27 ~10-29-10-31 10-25-10-27

Deuteron nucleus

~10-29 3×10-29- 5×10-31

Proton nucleus

<7×10-25 ~10-29 10-29


Hadronic EDM Timeline

2000 2010 2020

1E-24

1E-26

1E-28

1E-30

1E-32

ED

M L

imits

[ec

m]

ILL, n

PSI, n

SNS, n

BNL, p COSY, d

199Hg

129Xe

Future

129Xe, Rn, Ra


Electron EDM Timeline

2000 2010 2020

1E-24

1E-26

1E-28

1E-30

1E-32

ED

M L

imits

[ec

m]

Tl, e-

Polarmol.

Future

Short History of EDM• 1950’s neutron EDM experiment: a search for parity

violation (before the discovery of P-violation)• After P-violation was discovered it was realized EDMs

require both P,T-violation• 1960’s EDM searches in atomic systems• 1970’s Indirect Storage Ring EDM method from the

CERN muon g-2 exp.• 1980’s Theory studies on systems (polar molecules)

with large enhancement factors• 1990’s First exp. attempts w/ polar molecules.

Dedicated Storage Ring EDM method developed• 2000’s Proposal for sensitive srEDM exp. approved;

Magn. Opt. Traps developed, progress w/ polar mol.

EDMs of different systems Theta_QCD:

Super-Symmetry (SUSY) model predictions:

The results and best limits

• It now dominates the limits on many parameters• They expect another improvement factor ~3 - 5.


The spin precession relative to momentum in the plane is kept near zero. A vert. spin precession vs. time is an indication of an EDM (d) signal.

0a

dsd E

dt

E

E E

E

Vertical plates are placed everywhere around the ring to minimize vertical electric/radial B- fields from image charges

E-field plate module: The (26) FNAL Tevatron ES-separators would do

0.4 m

3 m

Beam position

Is the polarimeter analyzing power good at Pmagic? YES!

Analyzing power can be further optimized

Gas cluster ion beam surface treatment

Storage Ring EDMTechnical Review – 12/7/2009

Edward J. Stephenson, IUCF 15

Polarimeter Development

Polarimeter

(Half) Polarimeter in the ring:

cm

One target isshown. Wewant a targetavailable fromat least theleft, right, upand downdirections.

Quadrupoles hereare larger aperturefor clearance.

5° to 20°acceptance

Generic detector: (?) Multi-resistive plate chamber (?) Micro-megas (?) Gas electron multiplier (?) …other

Absorber to removelow analyzing powerparticles. (Detectorchoice can also givediscrimination.)

Equal rate readout pads

Rate = 800 /s/pad

In one store: 4105.1 δ




COSY ring:

Use EDDAdetector

COSY tests

EDDA detector:

Rings and bars to determine angles.

LEFT

UP

DOWN RIGHT

Azimuthal angles yield two asymmetries:

RL

RLEDM

UD

UDg

2




Target Concept

Target solution found at COSY:

15 mm

White noiseapplied to

electric fieldplates.

beam core

expanded vertical phase space

endview

maximumallowed at

COSY

Do enough particles penetrate far enough into the frontface to travel most of the way through the target?

This requires a comparison of the efficiency with model values.

Polarimeter rates:•Beam intensity with 2×1010 pol. protons/ ~103s and a detection efficiency of 1% 200KHz for ~3000cm2 area, or ~100Hz/cm2 on average but much higher at small radius. Design: ~1KHz/pad.

70 cm

Applying Micro-Megas TPC


• Differentiate between protons and deuterons

• Have a pointing accuracy of 0.5mrad/event

e-EDM experiment with atom in the world

EDM of stable alkaline atoms

Cesium Fountain EDM experiment (Harvey Gould et al., LBNL, California, USA)Projected accuracy de~1×10-29 e cm

EDM experiment of Cs and Rb in 1-D Optical Lattice(David Weiss et al., Penn. State Univ., USA)Projected accuracy de~5×10-30 e cm

Cesium EDM Experiment using Optical Dipole Force Traps (Heinzen et al., University of Texas, Austin, USA)Projected accuracy de~10-29 e cm

Cesium EDM Experiment using Optical Lattice (K. Honda, Tokyo Institute of Technology, Tokyo, Japan)

Many activities in the world ….


Ramsey’s method of separated fields

Status of the proton EDM experiment at BNL Yannis K. Semertzidis Brookhaven National Laboratory

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