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Precursor experiments to search forpermanent electric dipole moments

(EDMs) of protons and deuterons at COSY

September 15, 2011 Frank Rathmann (with help from Andreas, Bernd, Bill, and Kolya)

XIVth Int. Workshop on Polarized Sources, Targets & Polarimetry, St. Petersburg, Russia

Topics

Introduction Possible Precursor Experiments:

1. Depolarization using Snake and RF E Fields

2. Dual beam method (g-2 d)

3. Resonance Method with RF E-fields (Morse)

4. Resonance Method (Orlov, Morse, Semertzidis) Summary

2Precursor experiments to search for EDMs at [email protected]

EDM at COSY – COoler SYnchrotron

Cooler and storage ring for (polarized) protons and deuterons

p = 0.3 – 3.7 GeV/c

Phase space cooled internal & extracted beams

Injector cyclotron

COSY

… the spin-physics machinefor hadron physics

[email protected] 3Precursor experiments to search for EDMs at COSY

EDM at COSY – COoler SYnchrotron

Cooler and storage ring for (polarized) protons and deuterons

p = 0.3 – 3.7 GeV/c

Phase space cooled internal & extracted beams

Injector cyclotron

COSY

… an ideal starting pointfor a srEDM search


Mystery of matter-antimatter asymmetry

Electric dipole moment (EDM)

A permanent EDM of a fundamental particle violates both parity (P) and

time reversal symmetry (T).

Assuming CPT to hold, the combined symmetry CP is violated as well.

Search for Electric Dipole Moments


Sensitivity to NEW PHYSICS beyond the Standard Model

EDM searches - only upper limits up to now:

Huge efforts under way to improve limits / find EDMs



Future: Search for Electric Dipole Moments

485. WE-Heraeus-Seminar (July 0406, 2011) Search for Electric Dipole Moments (EDMs) at Storage Rings

http://www2.fz-juelich.de/ikp/edm/en/

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 !




particle p (GeV/c) E (MV/m) B (T)

proton 0.701 16.789 0.000

deuteron 1.000 -3.983 0.160

3He 1.285 17.158 -0.051

One machine with r ~ 30 m

An all-in-one machine: Protons

E-field only


5 10 15 20 25 30 350

20

40

60

80

100

Proton 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

An all-in-one machine: Deuterons

E and B fields


100 200 300 400 5000

10

20

B=0.1 TB=0.2 TB=0.3 T

Deuteron EDM

kinetic energy (MeV)

radi

us (

m)

100 200 300 400 50015

10

5

0

B=0.1 TB=0.2 TB=0.3 T

Deuteron EDM


radi

al E

-fie

ld (

MV

/m)

An all-in-one machine: Helions

E and B fields


100 200 300 400 5000

10

20

B=0.05 TB=0.1 TB=0.15 T

Helion EDM


radi

us (

m)

100 200 300 400 5000

10

20

30

B=0.05 TB=0.1 TB=0.15 T

Helion EDM


radi

al E

-fie

ld (

MV

/m)

2 beams simultaneously rotating in a ring (CW, CCW)

Approved BNL-Proposal:Goal for protons

Technological challenges !

Carry out proof of principle experiments (demonstrators) at COSY

• Spin coherence time (1000 s)• Beam positioning (10 nm)• Continuous polarimetry (< 1ppm)• E - field gradients (~ 17MV/m at 2 cm)

Circumference~ 200 m




)(105.2 29 yearonecmepd

[email protected] Precursor experiments to search for EDMs at COSY 12

COSY: Concept for Snake

• Should allow for flexible use at two locations

• Fast ramping (< 30s)

• Cryogen-free system

• Should be available in 2012

Bdl (Tm)

pn→{pp}sπ- at 353 MeV 3.329

PAX at COSY 140 MeV 1.994

PAX at AD 500 MeV 4.090

Tmax at COSY 2.88 GeV 13.887

ANKE

PAXPAX

ANKE


PE 1: Use a combination of a snake and RF fields

Snake

Snake only

Siberian snake turns spin closed orbit along longitudinal axis


SnakeRF E-field RF E-field

Snake + RF E-field, odd turns


2

nPnP )2cos()( 0 Snake + RF E-field, even turns



Snake + reversed RF E-fields depolarization


[email protected] 16

Parameters of a proton EDM measurement:•Tp=140 MeV

•ERF=1 MV/m, Lcavity=0.5 m

•Time of store 24h 6.31010 turns•=1 10-7 rad•Sensitivity:

• dp=10-17 ecm p=5.9 105 s

• dp=10-18 ecm p=5.9 107 s

2 1010 4 10

10 6 1010

0

0.2

0.4

0.6

0.8

d=10^-18 e cmd=10^-17 e cm

n (number of turns)

P(n

)P

(n)

n (number of turns)

dp=10-18 ecmdp=10-17 ecm

2

nPnP )2cos()( 0


Precursor experiments to search for EDMs at COSY



PE 2: Dual Beam Method (equivalent to g-2 d)

It seems possible to store protons and deuterons in COSY simultaneously.

• Assume dp=10-24 ecm.• Determine invariant spin axis of protons using polarimeter.

• Not clear whether one can get away with radial components of P only.

• Determine invariant spin axis for deuterons using polarimeter.• Difference between the two invariant spin axes sensitive to dd.

• Sensitivity similar to g-2 d: dd=10-19 ecm.

Polarimeter(determines pp and dp elastic)

p and d at same momentum


PE 3: Resonance Method with RF E-fields (Bill and Kolyas variation of PE1)

Polarimeter (dp elastic)

stored d

RF E-fieldvertical

polarization

spin precession governed by: (* rest frame)

Two situations:

1. B*=0 By = ER (= 70 G for ER=30 kV/cm) EDM effect2. E*=0 ER = - By no EDM effect

This way, the Edm signal gets accumulated during the cycle. Statistical improvement over PE 1 is about: . Brings us in the 10-24 ecm range for dd

5101/1000 ss

growsPP

dropsP

zx

y

22


PE 3: Simulation of resonance Method with RF E-fields and deuterons at COSY

Parameters: beam energy Td=50 MeVassumed EDM dd=10-20 ecmE-field 10 kV/cm

Constant E-field

Number of turns

E-field reversed every -/(G) 21 turns

Number of turns


PE 3: Simulation of resonance Method with RF E-fields and deuterons at COSY

Parameters: beam energy Td=50 MeVassumed EDM dd=10-20 ecmE-field 10 kV/cm

Linear extrapolation of P=sqrt(Px2+Py

2) for a time period of sc=1000 s (=3.7108 turns)

Number of turns

EDM effect accumulates

Polarimeter determines Px, Py and Pz


PE 4: Resonance Method of EDM Measurements in SR

Orlov, Morse, Semertzidis PRL 96 (2006)

*E

BBvddt

sd )(

Measurement using an all magnetic ring

• Sideways P, EDM produces growing Py

• Using two sub-beams with different v andmodulating v allows one to isolate d.

• Sensitivity dd=10-29 ecm/yr

• Idea was no longer pursued because systematic error is much larger.

• Systematic error estimates for all PEs require reliable spin tracking tools.

Top priority to make them available ASAP!• Next step:

• Scrutinize potential of different PEs• Identify PE with best systematic limit on dp,d.


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”



Spare transparencies

Frozen Spin Method (FSM)

Spin vector

Momentum vector

Lower energy particle

…just right

Higher energy particleSpin coherence time: 103 s for measurement on 10-29 e·cm level

2

2 ,

1

1

2

gG

c

EGBG

m

eG

For , the spin precession (magnetic moment)

relative to the momentum direction is given by

0 EB

G


Freezing Spin Precession with E-Fields

11

01

12

G

G

G > 0 for γ > 1, if only electric fields are applied

Magic momentum for protons: p = 700.74 MeV/c

G

mp

G 1

1

μp / μN = 2.792 847 356 (23) Gp = 1.7928473565μd / μN = 0.857 438 2308 (72) Gd = -0.14298727202μHe-3 / μN = -2.127 497 718 (25) G3He= -4.1839627399

Nuclear magneton: μN = eħ / (2mpc) = 5.050 783 24 (13) · 10-27 J T-1


polarized beam in ring

A

AS

one particle with magnetic moment

“spin tune”

“spin closed orbit vector”COn̂

s2AS

ring

makes one turn

if is simple fraction of periodic perturbing precession kick frequency

sresonances

stable polarizationS

if ║ COn̂


spin manipulation

there is an for every point of the orbitSnakes (non-vertical B field) affect

snakesCOn̂

COn̂

flippersramping through a resonance reverses COn̂

spin closed orbit

180o


Machine acceptance


lost

cooled

targetring acceptance

beam

In an ideal machine (like TSR-HD)→ Single-Coulomb scattering at

the target dominates beam loss

K. Grigoriev et al., NIMA 599,130 (2009)


Future: Time Reversal Invariance Test

COSY-TRIC: P-even, T-odd

Total polarization correlation coefficient Ay,xz leads to relative difference of current slopes

Milestone: Operation of Precision BCT with I/I<10-4

IBeam

time

COSY used as accelerator and detector:

PAX

Need for a high precision BCT


Status TRI Test at COSY

• Slow fluctuations in the measured BCT signal exceed the noise band at higher frequencies

Possible solution:Cryogenic Current Comparator, read out by low-temperature super-conducting quantum interference device

Highest resolution achieved: 250 pA/Hz

A. Steppke, IEEE Trans. Appl. Superc. (2009)

D. Eversheim Hyperfine Interact 193 (2009)

mitglied der helmholtz-gemeinschaft precursor experiments to search for permanent electric dipole...

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