XXIX Workshop on Recent Advances in Particle Physics and Cosmology Patrai, 14-16 April 2011 Status of the proton EDM experiment at BNLYannis K. SemertzidisBrookhaven National Laboratory + - Motivation Neutron EDM experiments Status of Storage Ring EDM experiments (proton & deuteron) Plan
The great mystery in our universe: matter dominance over anti-matter Observations From SM (CKM- Weak interactions):
+ - In Quantum Mechanics: a non-degenerate system with Spin is defined by the spin vector 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.
+ T - + - P - + A Permanent EDM Violates both T & P Symmetries:
+ - The Electric Dipole Moment precesses in an Electric field The EDM vector d is along the particle spin direction Yannis Semertzidis, BNL
A charged particle between Electric Field plates would be lost right away. + + -
B E B E µ µ d d ω2 d = 10-28 e cm E = 200 kV/cm δw = 10-7 rad/s ~1 turn/year Measuring an EDM of Neutral Particles H = -(d E+ μ B) ● I/I mI = 1/2 ω1 mI = -1/2
Spin precession at rest E + Compare the Precession Frequencies with E-field Flipped: - Yannis Semertzidis, BNL
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.
Important Stages in an EDM Experiment • Polarize:state preparation, intensity of beams • Interact with an E-field:the higher the better • Analyze:high efficiency analyzer • Scientific Interpretation of Result! Easier for the simpler systems Yannis Semertzidis, BNL
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): Yannis Semertzidis, BNL
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 Yannis Semertzidis, BNL
ABS Line ABS DR Central LHe Volume ~400 mK, ~1000 liters Upper Cryostat Services Reentrant Neutron Guide Upper Cryostat DR LHe Volume ~450 liters ~6 m 3He Injection Volume 3He Injection Volume Cosq magnet Lower Cryostat 4-layer m-metal shield SNS nEDM Experiment - Vertical Section View • The current value is < 3 x 10-26e•cm (90% C.L.) • Hope to obtain roughly < 8 x 10-28e•cm with UCN in superfluid He
Neutron EDM Timeline ILL, n 1E-24 PSI, n SNS, n 1E-26 1E-28 EDM Limits [ecm] 1E-30 1E-32 2000 2010 2020 Year Yannis Semertzidis, BNL
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… + + -
…but can be kept in a storage ring for a long time E E E E Yannis Semertzidis, BNL
The sensitivity to EDM is optimum when the spin vector is kept aligned to the momentum vector Momentum vector Spin vector E E E E Yannis Semertzidis, BNL
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. E E E E Yannis Semertzidis, BNL
Freezing the horizontal spin precession • The spin precession is zero at “magic” momentum (0.7 GeV/c for protons, 3.1GeV/c for muons,…) • 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 E No matter what the E-field value is the spin follows the momentum vector creating an ideal Dirac-like particle (g=2) E E Eliminates geometrical phase effect Equalizes the beta-functions of counter-rotating (CR) beams Closed orbits of the CR beams are the same E Yannis Semertzidis, BNL
There is an asymmetry between E and B-fields and g-2 precession • B-fields: Independent of velocity! • E-fields: Depends on velocity
Freezing the horizontal spin precession for the proton a=1.79, and deuteron a=-0.143 • 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
Storage Ring EDM experiments: • High beam intensities (1010-1011), with high polarization (>0.8), and low emittance are currently available • Large electric fields are possible (10-20MV/m) • Spin coherence time ~103s are possible • 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 • Direct access to charged particle EDMs
pEDM polarimeter principle: probing the proton spin components as a function of storage time Micro-Megas TPC detector and/or MRPC “defining aperture” polarimeter target extraction adding white noise to slowly increase the beam phase space carries EDM signal increases slowly with time carries in-plane precession signal
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 • December 2009, with a subsequent scientific approval at BNL. • 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 • COSY/IKP, Germany: deuteron ring • BNL, USA: proton “magic” ring
Technically driven pEDM timeline 14 17 11 12 13 15 16 18 19 20 • Two years R&D • One year final ring design • Two years ring/beamline construction • Two years installation
Sensitivity to Rule on Several New Models Electroweak Baryogenises GUT SUSY Gray: Neutron Red: Electron n current e current n target p, d target e target e-cm J.M.Pendlebury and E.A. Hinds, NIMA 440 (2000) 471
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, <10-7-10-5 rad CP-violating phase; an unprecedented sensitivity level. The deuteron EDM sensitivity is similar. • Sensitivity to new contact interaction: 3000 TeV • Sensitivity to SUSY-type new Physics:
Summary • Physics is a must do, positive or negative result can differentiate between models (BAU) • E-field issues understood well • Working 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 of clam 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 M.C. data (L-R)/(L+R) vs. Time [s]
After the review committee suggestion (T. Roser) : Take more beam very early and late M.C. data (L-R)/(L+R) vs. Time [s]
Hadronic EDMTimeline ILL, n 1E-24 PSI, n SNS, n 1E-26 BNL, p COSY, d 1E-28 EDM Limits [ecm] 199Hg 1E-30 129Xe 129Xe, Rn, Ra 1E-32 2000 2010 2020 Future Yannis Semertzidis, BNL
Electron EDM Timeline Tl, e- 1E-24 Polar mol. 1E-26 1E-28 EDM Limits [ecm] 1E-30 1E-32 2000 2010 2020 Future Yannis Semertzidis, BNL
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.