February 24, 2014 Frank Rathmann on behalf of JEDI

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Search for Permanent Electric Dipole Moments at COSYStep 1: Spin coherence and systematic error studies

(Proposal 216.1)

February 24, 2014 Frank Rathmann on behalf of JEDI42nd Meeting of the COSY Programm Advisory Committee

Search for Permanent Electric Dipole Moments at COSY 2

Introduction

Present proposal merges activities from #176 and #216 under the flag of JEDI.

Aim: Use expertise of both groups to develop instrumentation and techniques for EDM searches at storage rings.

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3

Outline

Three recent achievementsProposed experimental investigations:

1. Spin coherence time studies (contin. of #176)2. RF Wien Filter 3. Systematic study of machine imperfections using two

straight section solenoids Beam request

Search for Permanent Electric Dipole Moments at [email protected]


A 1: Spin coherence time

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Sextupole corrections of higher order effects yield


A 2: Spin tune determination

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Using time stamping technique from Up/Do asymmetry

Spin tune determined to in .Average in one cycle () known to .

Understand implications for future precision experiments.


A 3: Harmonic dependence of

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10 100 1 103 1 104

1

100

1 104

1 106

1 108

1 1010K=1 (630 kHz)K=-1 (871 kHz)K=2 (1380 kHz)K=2 (1620 kHz)

Deuterons RF-B solenoid

Beam energy (MeV)

Spin

coh

eren

ce ti

me

(s)

Spi

n co

here

nce

time

(s)

235 MeV

Beam energy (MeV)

Observation of enhancements of for p (and d) requires more

flexible polarimeter

𝑓 RF=(𝛾𝐺±𝐾 ) 𝑓 rev

𝜏SC= 12𝜋 2𝐶2 𝑓 rev 𝐺

2𝛾 2 𝛽4 ⟨( ∆𝑝𝑝 )

2⟩−1

𝐶=1− 𝜂𝛽2 (1+ 𝐾

𝛾𝐺 )Theory: N.N.Nikolaev

Observed oscillating , driven by RF solenoid at different harmonics


1. Spin coherence time studies (contin. of #176)Removing spin tune spread with sextupole fields:

• Observe result in lifetime (SCT) of horizontal polarization• Major run in weeks 35 and 36 (August/September) 2013 (lots of data)

[email protected]

Example of data measured with the time-marking DAQ system

HORIZONTAL POLARIZATION

SCT

signs changed toshow linear effect

black = spin downblue = spin up

Zero crossing of inverse slope locates best SCT.

Initi

al P

olar

izat

ion

Slop

e


First 2-D Map: vs MXS vs MXG

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MXG

MXS

0 20

20

40+

+

+

+

+

+

+

+

+

+

+ Best SCT points for large horizontal emittance

+ Best SCT points for large Δp/p (longitudinal)

+

+

+

+

+

Units: percent of power supply full scale.

ξX = 0

ξY = 0

Location of best SCT is closely associated with location of vanishing chromaticity.

• Each sextupole field scan locates one point on 2D map

• Beam set up to emphasize different sources of decoherence, which can be corrected with sextupole fields.


Chromaticity studies (tests in week 7)

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Chromaticity defines the tune change with respect to momentum deviation

• Strong connection between and observed.• COSY Infinity based model predicts negative natural chromaticities and .• Measured natural chromaticity: and • changed from 1 to 3 in 2013, although similar machine settings were used.

To be studied:• Vary sextupoles of arcs and straights: benchmark changes in model.• Vary quadrupoles and orbit excitations to search for sources of variations.• Examine long term stability.• Ramp up dipole magnets to investigate influence of machine history on .

Measurement of chromaticityTwo methods for beam energy shift applied1. Variation of electron cooler voltage2. Variation of cavity frequency

Tune measurement:• Sweep frequency for beam excitation and

measure response to locate betratron frequency• Measure revolution frequency using Schottky

spectrum

Horizontal Vertical

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Chromaticity: Arc sextupoles Three families in the arcs: (MXS, MXL, MXG)Non-vanishing dispersion in the arcs, large influence of chromaticity expected

Measurement / Model (change per %)

MXS: / /

MXL: / /

MXG: / /

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Chromaticity: Straight section sextupoles

Test of combined familiy of four straight section sextupoles (MXT: 2-3-10-13)

Dispersion minimized in straights, no impact on chromaticity expected

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Straight section sextupoles show no effect on chromaticity

Search for Permanent Electric Dipole Moments at COSY [email protected]

Spin coherence time studies: Required time2 weeks are requested to further explore ways to improve the SCT.

1. Make the lines of zero chromaticity coincide• Recent machine development studies provide the slopes for chromaticity

vs MXL (not tried before). A negative MXL setting should pull the zero chromaticity lines toward each other.

2. Explore straight section sextupoles (no effect on chromaticity)• Sensitivity of SCT seen before (but weaker). Does different degree of

freedom help?

Additional information would be useful:

3. Revisit RF-solenoid-induced oscillations at low field• Present analysis hampered by differential extraction on ridge target.

4. Explore contribution of emittance to SCT in white noise extraction


2. RF Wien Filter

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Precursor EDM concept: Use RF Wien filter to accumulate EDM signal

Insert RF-dipole into ceramic chamber


RF Wien Filter: Field calculations

𝒛 (𝐦)

𝒙 (𝐦)

𝑩𝒙(𝐓)

Main field componentat ,

Main field componentat ,

𝒛 (𝐦)

𝒙(𝐦

)

𝑬𝒚(

𝐕/𝐦

)

𝒛 (𝐦)

𝒙(𝐦

)

𝑭𝒚(𝐞𝐕/

𝐦)

Integral compensation of Lorentz force at


RF Wien Filter: First tests with beamCommissioning:• Pulsed mode, pulses, each long, • BPM sensitivity at betatron sideband frequency used to adjust and to

match Wien filter condition,• Diagnosis using COSY BCT

• Compensation achieved down to ~7 % beam loss.𝐼 ( A)

Bea

m lo

ss (%

)

Matching of phase of at

Bea

m lo

ss (%

)E-B phase ()

Requested 2 weeks of beam time will be used to fully commission the RF Wien filter, should do same job as RF solenoid.

Matching of RF field to RF at


Systematic study of machine imperfections using two straight section solenoids

Idea: The precise determination of the spin tune can be exploited to map out the imperfections of COSY.

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COSY provides two solenoids in opposite straight sections:

1. one of the compensation solenoids of the 70 kV cooler: ,2. The main solenoid of the 2 MV cooler: .

Both are available dynamically in the cycle, i.e., their strength can be adjusted on flattop.

Systematic effects from machine imperfections limit the achievable precision in a precuror experiment using an RF Wien filter.


Imperfection kick: Deuterons at MeV

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The requested 2 weeks of beam time shall be used to study static imperfections with artificial spin rotations and induced by two straight section solenoids.

Ideal machine with vanishing static imperfections: Saddle point at the origin

sea level at

Intrinsic imperfection kick shifts saddle point away from origin

Location of imperfection:


Beam Request

• We request in total 6 weeks of beam time for the activities:1. Spin coherence time studies (contin. of #176) (2 weeks),2. RF Wien Filter (2 weeks),3. Systematic study of machine imperfections

using two straight section solenoids (2 weeks),preceeded by 1 MD week.

• Investigations difficult, require time consuming machine tuning. Beam time should be scheduled as single block.

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Backup slides

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Precursor experiments: RF methods

Use existing magnetic machines for first direct EDM measurements

Method based on making spin precession in machine resonant with orbit motion

Two ways: 1. Use an RF device that operates on some harmonics of the spin

precession frequency

2. Operate ring on an imperfection resonance


Precursor experiments: 1. 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 EDM.Approach pursued for a first direct measurement at COSY.

„Magic RF Wien Filter“ no Lorentz force Indirect EDM effect

Observable:Accumulation of vertical polarization during spin coherence time

Polarimeter (dp elastic)

stored d

RF E(B)-field In-plane polarization

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


Precursor experiments: 1. Resonance Method for deuterons at COSY Parameters: beam energy

assumed EDME-field

𝐭𝐮𝐫𝐧𝐧𝐮𝐦𝐛𝐞𝐫

𝑷 𝒙 𝑷 𝒛 𝑷 𝒚

EDM effect accumulates in

1. Resonance Method Operation of „magic“ RF Wien filter


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

beam energy

Spin coherence time may depend on excitation and on harmonics .𝐾


Parameters: beam energy assumed EDME-field

EDM effect accumulates in

𝑃 𝑦

𝐭𝐮𝐫𝐧𝐧𝐮𝐦𝐛𝐞𝐫

𝑷 𝒚

Precursor experiments:1. Resonance Method for deuterons at COSY

Linear extrapolation of for a time period of yields a sizeable .


Development: RF E/B-Flipper (RF Wien Filter)

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1. Upgrade test flipper with electrostatic field plates ready end of year.2. Build lower power version using a stripline system3. Build high-power version of stripline system ( )

Work by S. Mey, R. Gebel (Jülich)J. Slim, D. Hölscher (IHF RWTH Aachen)


Precursor experiments:2. Resonant EDM measurement with static Wien Filter

Machine operated on imperfection spin resonance at

𝑷𝒙(𝒕

)

𝒕 (𝐬)Similar accumulation of EDM signal, systematics more difficult, strength of imperfection resonance must be suppressed by closed-orbit corrections.

Spin rotation in phase with orbit motion

without static WF


1 Make the lines of zero chromaticity coincide.Recent machine development studies provide the slopes for chromaticity vs. MXL (not tried before).A negative MXL setting should pull the zero chromaticity lines toward each other.A “best case” chromaticity setup might work, as before.

ξX,Y = 0

2 Explore straight section sextupoles (no effect on chromaticity)Sensitivity of SCT seen before (but weaker).Does different degree of freedom help?

Based on analysis now underway, additional information would be useful:

3 Revisit RF-solenoid-induced PY oscillations at low field.Present analysis hampered by differential extraction on ridge target.

4 Explore contribution of emittance in white noise extraction to SCT.

[email protected]


Removing spin tune spread with sextupole fieldsObserve result in lifetime (SCT) of horizontal polarizationMajor run in weeks 35 and 36 (August/September) 2013, lots of data

MXG

MXS

0 20

20

40+

+

+

+

+

+

+

+

+

+

Best SCT points for large horizontal emittance

Best SCTpoints forlarge Δp/p(longitudinal)

+

+

+

+

+

Units are inpercent of power supply full scale.

Example of datameasured with the

time-markingDAQ system

HORIZONTAL POLARIZATION

signs changed toshow linear effectblack = spin down

blue = spin up

Beam set up toemphasize different

sources of decoherence,which can be correctedwith sextupole fields.

Each sextupolefield scan locates

one point on2-D map.

Zero crossingof inverse slope

locates best SCT.

SCT

FIRST2-D

MAP

Initi

alPo

lariz

atio

nSl

ope

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Search for Permanent Electric Dipole Moments at COSY 30MXG

MXS

0 20

20

40+

+

+

+

+

+

+

+

+

+

Best SCT points for large horizontal emittance

Best SCTpoints forlarge Δp/p(longitudinal)

+

+

+

+

+

Units are in percentof power supplyfull scale.

ξX = 0

ξY = 0

Location of best SCT is closelyassociated with location ofvanishing chromaticity.

Results comparable to calculated slopesfor best SCT (X, Y emittance, andlongitudinal Δp/p) and zero chromaticity.

Slopes scaled topercent units. Offsets arearbitrary.

Chromaticity effects are planar.Sextupoles adjust constant term.

COSY-Infinity calculationsby Marcel Rosenthal

best fit tochromaticitydata

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Stability 5 days/nights of measurement

Measurements using cavity (method 2)

MXS @ 2%shift of +0.3 expected

MXS @ 2%shift of -0.22 expected

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Machine History Super Cycle:

1. cycle: no injection, dipole ramped to larger target momenta for 4- 5 seconds2. cycle: usual measurement cycle

time

B-Field ofbending dipoles

measurementAdditíonal dipole rampTarget momenta of additional ramp:1: 2028 MeV/c2: 2513 MeV/c3: 3097 MeV/c4: 3700 MeV/c5: cycle 1 removed(default target momentum: 970 MeV/c)

decreasing

restoring

increasing

restoring

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33

Charge symmetric No EDM ()

Do particles (e.g., electron, nucleon) have an EDM?


: MDM: EDM

Physics: Fundamental Particles


Physics: Symmetries

Parity:

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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

[email protected] 35Search for Permanent Electric Dipole Moments at COSY

Permanent EDMs violate P and T.Assuming CPT to hold, CP violated also.

Not Charge symmetric (aligned w/ spin)

EDMs: Discrete Symmetries

36

J.M. Pendlebury: „nEDM has killed more theories than any other single expt.“


Physics: Potential of EDMs


For transverse electric and magnetic fields in a ring ( ),anomalous spin precession is described by Thomas-BMT equation:

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)

Principle: Frozen spin Method

Magic rings to measure EDMs of free charge particles

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

Status: Approved BNL-ProposalSubmitted to DOEInterest FNAL!

Goal for protons


Beat systematics: BNL Proposal

year)(onecme105.2 29 pd

CW CCWPolarization EDM Sokolov-TernovGravitation

CW & CCW beams cancels systematic effects

Many technological challenges need to be met


srEDM searches: Technogical challenges

Charged particle EDM searches require development of a new class of high-precision machines with mainly electric fields for bending and focussing.

Related topics:

• Electric field gradients • Spin coherence time • Continuous polarimetry • Beam positioning

• Spin tracking

These issues must be addressed experimentally at existing facilities

40Search for Permanent Electric Dipole Moments at [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=24.665 m

Challenge: Electric field for magic rings

Challenge to produce large electric field gradients

Rfield only


Challenge: Niobium electrodes

Show one slide on JLAB data HV devicesDPP stainless steel fine-grain Nb

large-grain Nblarge-grain Nb single-crystal Nb

Large-grain Nb at plate separation of a few cm yields ~20 MV/m


Challenge: Electric field for magic ringsElectrostatic separators at Tevatron used to avoid unwanted interactions

- electrodes made from stainless steel

Routine operation at spark/Year at MV/m

L~2.5 m

Need to develop new electrode materials and surface treatments

~July 2013: Transfer of separator unit plus equipment from FNAL to Jülich

AAS

one particle with magnetic moment

“spin tune”

“spin closed orbit vector”COn̂

s2AS

ring

makes one turn

stable polarizationS

if ║ COn̂


Challenge: Spin coherence time

Spin closed orbit

Challenge: Spin coherence time


We usually don‘t worry about coherence of spins along

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 machines with frozen spin.

At injection all spin vectors aligned Later, spin vectors are out of phase in the horizontal plane

Longitudinal polarization vanishes!

COn̂

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

Challenge: SCT stimates (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:

𝛿𝜃=𝐺𝛿𝛾 𝛿𝛾cos𝜔𝑡→ cos (𝜔𝑡+𝛿𝜃 )

𝜏𝑠𝑐 ≈ 1𝑓 rev𝐺

2 ⟨𝛿𝛾 2 ⟩≈ 1𝑓 rev 𝐺

2𝛾2 𝛽4 ⟨(𝛿𝑝𝑝 )2⟩

−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

Spin coherence time for deuterons may be × larger than for protons𝟏𝟎𝟎

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


… an ideal starting pointfor a srEDM search


New Idea: Ivan Koop‘s spin wheel

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B𝑑𝑆𝑑𝑡 =𝑑×𝐸+𝜇×𝐵

By appropriate choice of magnetic field, the spin vector rotates fast frequencies of the order kHz

Jülich has expertise in SQUIDs, state-of-the art measurements allow for is

(

This would revolutionize the way we conceive EDM (and in general polarization) experiments, because frequencies become directly measureable.


How Ivan‘s spin wheel would work?

[email protected]

Frequency

B field

EDM =0

EDM ≠ 0

∼ ⟨ Δ 𝑦 ⟩

Find the value of B wherespin precession frequency

disappears


SQUIDs: Precision tools for accelerators

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Possible applications in accelerators, all of which are needed for srEDM experiments

1. Beam current transformers2. Beam position monitors3. Beam polarimeters

Begin development with a measurement of the noise spectrum using three coils:

• Coil 35mm away from center ANKE chamber• Combined coils in same housing

• GHz range (one pickup loop)• MHz range (several hundered loops)

• Fluxgate sensor • kHz range

Measurement of noise spectrum at COSY in MD week, July 2013


New Idea: Direct measurement of electron EDM

[email protected]

Bill Morse (BNL EDM): , ,

Nobody knows where CPV is hiding, may well be in the leptonic sector

Needs a dedicated R&D effort

Very attractive:• Tests all ingredients of srEDM experiments with • Could develop into an independent long-term project

Polarimetry is an issue

Goal:

Could be an option for FNAL using the electrostatic Tevatron separators

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 , ,

Common magnetic-electrostatic deflectors

Dedicated ring

4 EDM measurement of , , at Dedicated ring


Timeline: Stepwise approach all-in-one machine for JEDI

Time scale: Steps 1 and 2: years (i.e., in POF 3)Steps 3 and 4: years

52

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”


February 24, 2014 Frank Rathmann on behalf of JEDI

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Transcript of February 24, 2014 Frank Rathmann on behalf of JEDI