spin – physics, edm searches in storage rings

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SPIN – Physics,EDM searches in Storage Rings

August 14, 2012 Frank Rathmann

5th GEORGIAN - GERMAN SCHOOL AND WORKSHOP IN BASIC SCIENCE

2

Topics

Introduction Search for Electric Dipole Moments Spin coherence time First direct measurement

Resonance Method with RF E(B)-fields Conclusion

SPIN – Physics, EDM searches in Storage [email protected]

SPIN – Physics, EDM searches in Storage Rings 3

Introduction: Structure of Matter

[email protected]


Introduction: Four interactions (forces)

interaction couples to mediators(bosons) strength

strong color gluon 1038

electromagnetic electric charge photon 1036

weak weak charge W und Z 1025

gravitational mass graviton (?) 1

Matter consists of fermions, they attract or repel each other by exchanging bosons.

[email protected]


Introduction: Standard model of elementary particles

Fermions Bosons

• All particles (and their corresponding anti-particles) feature

1. mass2. charge, and3. spin

The spin vector of a particle is associated with a magnetic moment,

��[email protected]


Burning questions http://particleadventure.org/beyond_start.html

• Why do we observe matter and almost no antimatter if we believe there is a symmetry between the two in the universe?

• What is this "dark matter" that we can't see that has visible gravitational effects in the cosmos?

• Why can't the Standard Model predict a particle's mass?• Are quarks and leptons actually fundamental, or made up

of even more fundamental particles? • Why are there exactly three generations of quarks and

leptons? How does gravity fit into all of this?

[email protected]

http://particleadventure.org/beyond_start.html

http://particleadventure.org/beyond_start.html


What caused the Baryon asymmetry?

[email protected]

Carina Nebula: Largest-seen star-birth regions in the galaxy

Observed 610-10 WMAP+COBE (2003)

SM expectation ~10-18

nnn BB /)(

What happened to the antimatter?


Symmetries

Parity:

[email protected]

𝑷 :(𝒙𝒚𝒛 )→(− 𝒙−𝒚− 𝒛 )

C-parity (or Charge parity): Changes sign of all quantized charges• electrical charge,• baryon number,• lepton number,• flavor charges, • Isospin (3rd-component)

T-Symmetry: 𝑻 :𝒕→− 𝒕

Physical laws are invariant under certain transformations.

What caused the Baryon asymmetry?

[email protected] SPIN – Physics, EDM searches in Storage Rings 9

Sakharov (1967): Three conditions for baryogenesis

1. B number conservation violated sufficiently strongly2. C and CP violated, B and anti-Bs with different rates3. Evolution of universe outside thermal equilibrium

Carina Nebula: Largest-seen star-birth regions in the galaxy

Observed 610-10 WMAP+COBE (2003)

SM expectation ~10-18

nnn BB /)(


Dipole moments

Magnetic dipole moment

[email protected]

Electric dipole moment

Two electric charges separated by a distance

+𝑞−𝑞 𝑙

Two magnetic charges separated by a distance


Particles might have, besides mass, charge, and spin (magnetic moment ), an Electric Dipole Moment ?

[email protected]

Permanent EDMs violate parity P and time reversal symmetry TAssuming CPT to hold,

combined symmetry CP violated as well.

Electric Dipole Moments (EDMs)

[email protected] 12SPIN – Physics, EDM searches in Storage Rings

EDMs are candidates to solve mystery of matter-antimatter asymmetry may explain why we are here!

13

History of neutron EDM limits

[email protected] SPIN – Physics, EDM searches in Storage Rings

Adopted from K. Kirch

• Smith, Purcell, Ramsey PR 108, 120 (1957)

• RAL-Sussex-ILL(dn 2.9 10-26 ecm) PRL 97,131801 (2006)

Sensitivity to NEW PHYSICS beyond the Standard Model

EDM searches - only upper limits, in (up to now):

Huge efforts underway to improve limits / find EDMs


Limits for Electric Dipole Moments

Particle/Atom Current EDM Limit Future Goal equivalent

Neutron

Proton

Deuteron ?


Why also EDMs of protons and deuterons?

Proton and deuteron EDM experiments may provide one order higher sensitivity.

In particular the deuteron may provide a much higher sensitivity than protons.

Consensus in the theoretical community:Essential to perform EDM measurements on different targets with similar sensitivity:

• unfold the underlying physics,• explain the baryogenesis.

NEW: EDM search in time development of spin in a storage ring:

“Freeze“ horizontal spin precession; watchfor development of a vertical component !


Search for Electric Dipole Moments

0G

Edts

dd

NEW: EDM search in time development of spin in a storage ring:

A magic storage ring for protons (electrostatic), deuterons, …

“Freeze“ horizontal spin precession; watchfor development of a vertical component !


Search for Electric Dipole Moments

particleproton

deuteronOne machine

with m

0G

Edts

dd

Two storage ring projects being pursued

(from R. Talman) (from A. Lehrach)


BNL for protons all electric machine Jülich, focus on deuterons, or a combined machine

CW and CCW propagating beams

Most recent: Richard Talmans concept for a Jülich all-in-one machine


Iron-free, current-only, magnetic bending, eliminates hysteresis

A

B

A B

2 beams simultaneously rotating in an all electric ring (cw, ccw)

Approved BNL-ProposalSubmitted to DOEGoal for protons

Technological challenges !

Carry out proof of principle experiments (demonstrators) at COSY

• Spin coherence time • Beam positioning • Continuous polarimetry • E - field gradients

Circumference


BNL Proposal

year)(onecme105.2 29 pd


Magnetic moment, spin, g and G

[email protected]

𝜇𝑁=𝑒 ∙ h

2 ∙𝑚𝑝=5.05078324 J T −1

The nuclear magneton

particle spin charge proton

deuteron3He

𝜇=𝑔 ∙𝜇𝑁 ∙𝑚𝑝

𝑚 ∙𝑍 ∙𝑠

The frozen spin Method


For transverse electric and magnetic fields in a ring ( ),anomalous spin precession is described by

0 EB

cE

pmGBG

mq

G

2

Magic condition: Spin along momentum vector

1. For any sign of , in a combined electric and magnetic machine

2. For (protons) in an all electric ring

2

2gG

222

2

1

GBc

GGBcE

x

Gmp

pmG

0

2

cMeV74.700 (magic)

Magic condition: Protons

Case 1: field only

23SPIN – Physics, EDM searches in Storage [email protected]

5 10 15 20 25 30 350

20

40

60

80

100Proton EDM

E-field (MV/m)

radi

us (m

)

r1 E( )

E

r2 250 md 0.48 Gd Zd 8.44

r2 280 m3He 0.0575 G3He Z3He 21.959

𝐸=17 MV /m

𝑟=24.665m


Magic condition: Protons

Case 2: and fields

magic energy

𝐵>0 𝐵<0magic energy

𝐵>0 𝐵<0

Magic condition: Deuterons

and fields


Magic condition: Helions


and fields


particleproton

deuteron

Parameters for Richard Talmans all-in-one machine

𝒓=𝟏𝟎𝐦

• Fitting such a machine into the COSY building favors lower momenta.

Talman/Gebel give maximum achievable field of copper

magnets of ~ 0.15 T.

EDM at COSY – COoler SYnchrotron

Cooler and storage ring for (polarized) protons and deuterons

Phase space cooled internal & extracted beams

Injector cyclotron

COSY

… the spin-physics machinefor hadron physics


EDM at COSY – COoler SYnchrotron

Injector cyclotron

COSY

… an ideal starting pointfor a srEDM search


Cooler and storage ring for (polarized) protons and deuterons

Phase space cooled internal & extracted beams

AAS

one particle with magnetic moment

“spin tune”

“spin closed orbit vector”COn

s2AS

ring

makes one turn

stable polarizationS

if ║ COn


Spin closed orbit

Spin coherence


We usually don‘t worry about coherence of spins along COn

At injection all spin vectors aligned (coherent)

After some time, spin vectors get out of phase and fully populate the cone

Polarization not affected!

Situation very different, when you deal with S

COn

At injection all spin vectors aligned After some time, the spin vectors are all out of phase and in the horizontal plane

Longitudinal polarization vanishes!

COn

In an EDM machine with frozen spin, observation time is limited.

Estimate of spin coherence times (N.N. Nikolaev)


One source of spin coherence are random variations of the spin tune due to the momentum spread in the beam

and is randomized by e.g., electron cooling

Estimate:

Spin coherence time for deuterons may be larger than for protons

𝛿𝜃=𝐺𝛿𝛾 𝛿𝛾

cos𝜔𝑡→cos (𝜔𝑡+𝛿𝜃 )

𝜏𝑠𝑐 ≈1

𝑓 rev𝐺2 ⟨𝛿𝛾 2 ⟩

≈ 1𝑓 rev𝐺

2𝛾2 𝛽4 ⟨ 𝛿𝑝𝑝2⟩

− 1

𝑇 kin=100 MeV 𝑓 rev=0.5 MHz

𝜏𝑠𝑐 (𝑝 )≈3 ∙103 s 𝜏𝑠𝑐 (𝑑)≈5 ∙105 s

𝐺𝑝=1.79 𝐺𝑑=−0.14

First measurement of spin coherence time

Polarimetry:

Spin coherence time:


from Ed Stephensonand Greta Guidoboni

decoherencetime

oscillationcapture

5 s 25 s 5 s

2011 Test measurements at COSY

Topics

Why EDMs? Search for EDMs using storage rings Two projects, at BNL and Jülich Spin coherence time First direct measurement

Resonance Method with RF E(B) –fields Polarimetry Summary



Resonance Method with RF E-fields

Polarimeter (dp elastic)

stored d

RF E-fieldvertical

polarization

spin precession governed by: (* rest frame)

Two situations:

1. EDM effect2. no EDM effect

This way, the EDM signal is accumulated during the cycle. • Statistical improvement over single turn effect is about: . • Brings us in the range for .

5101/1000 ss

• But: Flipping fields will lead to coherent betatron oscillations, with hard to handle systematics.


Simulation of resonance Method with RF E-fields for deuterons at COSY

Parameters: beam energy assumed EDME-field

Constant E-field

Number of turns

E-field reversed every

Number of turns


Simulation of resonance Method with RF E-fields for deuterons at COSY

Parameters: beam energyassumed EDME-field

Linear extrapolation of for a time period of

Number of turns

EDM effect accumulates

Polarimeter determines

22zx PPP


Resonance Method with „magic“ RF Wien filter

Avoids coherent betatron oscillations of beam. Radial RF-E and vertical RF-B fields to observe spin rotation due to EDMApproach pursued for a first direct measurement at COSY.

„Magic RF Wien Filter“ no Lorentz force

Statistical sensitivity for in the range to range possible.• Alignment and field stability of ring magnets• Imperfection of RF-E(B) flipper

„Indirect“ EDM effect

Tilt of precession plane due to EDM

Observable:Accumulation of vertical polarization during spin coherence timePolarimeter (dp elastic)

stored d

RF E(B)-field

Transverse polarization

Operation of „magic“ RF Wien filter


Radial E and vertical B fields oscillate, e.g., with (here ).

Spin coherence time may depend on excitation and on chosen harmonics

beam energy


Simulation of resonance Method with „magic“ Wien filter for deuterons at COSYParameters: beam energy

assumed EDME-field

Linear extrapolation of for a time period of

EDM effect accumulates in .

𝜔=2𝜋 𝑓 𝑟𝑒𝑣𝐺𝛾=−3.402×105 Hz

turn number

𝑃 𝑥 𝑃 𝑧 𝑃 𝑦

Preliminary, based on K. Nikolaevs derivation of the combined rotation matrices of E/B flipper and ring


Simulation of resonance Method with „magic“ Wien filter for deuterons at COSY

Linear extrapolation of for a time period of .


EDM effect accumulates in

𝑃 𝑦

turn number

𝑃 𝑦

Simulation of resonance Method with Magic Wien filter for deuterons at COSY

Linear extrapolation of for a time period of .



EDM effect accumulates in

𝑃 𝑦

turn number

Some polarimetry issuespC and dC polarimetry is the currently favored approach for the pEDM experiment at BNL


srEDM experiments use frozen spin mode, i.e., beam mostly polarized along direction of motion,

most promising ring options use cw & ccw beams.

• scattering on C destructive on beam and phase-space,• scattering on C determines polarization of mainly

particles with large betatron amplitudes, and• is not capable to determine . • For elastic scattering longitudinal analyzing powers are tiny (violates parity).

Ideally, use a method that would determine .

Exploit observables that depend on beam and target polarization


b eam1 ��=(𝑃 𝑥𝑃 𝑦𝑃 𝑧 )t arget (¿beam2)��=(𝑄𝑥

𝑄𝑦𝑄𝑧

)

𝜎𝜎0

=1+𝐴𝑦 [ (𝑃 𝑦+𝑄𝑦 ) cos𝜑− (𝑃 𝑥+𝑄𝑥 ) sin 𝜑 ]

Spin-dependent differential cross section for

Analyzing powerSpin correlations

In scattering, necessary observables are well-known in the range MeV (not so for or ).

𝑥 (sideways)

𝑦 (up)

𝑧 (along beam)

𝜑

𝜃

How could one do that, determine ?

Suggestion 1: Use a polarized storage cell target


Detector

• Detector determines of cw & ccw beams separately, based on kinematics.• Alignment of target polarization along axes by magnetic fields. Leads to

unwanted MDM rotations absolute no-go in EDM experiments.

cell

CW CCW


Suggestion 2: Use colliding beam from external source

• Collide two external beams with cw and ccw stored beams.• Energy could be tuned to match detector acceptance.• Polarization components of probing low-energy beam can be made large, would

be selected by spin rotators in the transmission lines.• Luminosity estimates necessary

Detector

Polarized ion source(~10 MeV)


𝜎𝜎0

=1+𝐴𝑦 [ (𝑃 𝑦+𝑸𝒚 ) cos𝜑− (𝑃𝑥+𝑸 𝒙 ) sin 𝜑 ]

cw beam𝑃=(𝑃 𝑥𝑃 𝑦𝑃 𝑧) probingbeam ��=(𝑄𝑥

𝑄𝑦𝑄𝑧

)=(𝑄𝑥

00 ) ,( 0

𝑄𝑦0 ) ,∨( 0

0𝑄𝑧

)



Suggestion 3: Use directly reactions from colliding beams

Detector

CW CCW

Requires luminosity, -functions at IP should be rather small.• Advantage over suggestion 2. is that supports luminosity.• Disadvantage is that sensitivity comes mainly from terms with and .• Detailed estimates necessary.

𝜎𝜎0

=1+𝐴𝑦 [ (𝑃 𝑦+𝑄𝑦 ) cos𝜑− (𝑃 𝑥+𝑄𝑥 ) sin 𝜑 ]

cw beam𝑃=(𝑃𝑥𝑃𝑦𝑃𝑧 ) ccw beam��=(𝑄𝑥

𝑄𝑦𝑄𝑧

)

Luminosity estimate for the collider option


𝐿(𝑇 , 𝛽 )=𝑁1𝑁2 𝑓 rev(𝑇 )𝑛𝑏

4𝜋 𝜎 (𝛽)2

𝜎 (𝛽)=√𝜖 ∙ 𝛽

Conditions:

k inetic energy(MeV )

Luminos

ity𝛽=10 m

𝛽=1m

𝛽=0.1m

T magic=232.8 MeV

Even under these very optimistic assumptions, event rate will be rather low.

Stepwise approach in the JEDI project

Step Aim / Scientific goal Device / Tool Storage ring

1Spin coherence time studies Horizontal RF-B spin flipper COSY

Systematic error studies Vertical RF-B spin flipper COSY

2COSY upgrade Orbit control, magnets, … COSYFirst direct EDM measurement at RF-E(B) spin flipper Modified

COSY

3 Built dedicated all-in-one ring for p, d, 3He

Common magnetic-electrostatic deflectors

Dedicated ring

4 EDM measurement of p, d, 3He at

Dedicated ring


Time scale: Steps 1 and 2: < 5 yearsSteps 3 and 4: > 5 years

srEDM cooperations

Institutional (MoU) and Personal (Spokespersons …) Cooperation, Coordination

International srEDM Network

srEDM Collaboration (BNL)(spokesperson Yannis Semertzidis)

JEDI Collaboration (FZJ)(spokespersons: A. Lehrach, J. Pretz, F.R.)

Common R&DRHIC EDM-at-COSY

Beam Position Monitors Polarimetry (…) Spin Coherence Time

Cooling Spin Tracking (…)

DOE-Proposal (submitted)

Study Group

First direct measurement Ring Design

JEDI pEDM Ring at BNL

HGF Application(s) CD0, 1, …


EDM Workshop at ECT* (Trento)


October 1-5, 2012

Organizing committee

Jülich Hans Ströher [email protected] Rathmann [email protected] Wirzba [email protected]

BrookhavenMei Bai [email protected] Marciano [email protected] Semertzidis [email protected]

http://www.ectstar.eu/



• Measurements of EDMs are extremely difficult, but the physics is fantastic!

• Two storage ring projects, at BNL and Jülich

• All-in-one machine with copper-only magnets

• Pursue spin coherence time measurements at COSY

• First direct EDM measurement at COSYResonance Method with RF E(B) -fields

• Polarimeter concepts to be addressed by simulations

• JEDI collaboration established


Summary


Georg Christoph Lichtenberg (1742-1799)

“Man muß etwas Neues machen, um etwas Neues zu sehen.”“You have to make (create) something new,

if you want to see something new”

[email protected]

spin – physics, edm searches in storage rings

Documents

edm searches

storage ringsaugust

storage rings5

storage rings9sakharov

storage rings6

storage rings8cparity

storage rings3 introduction

storage rings4 introduction