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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.
f.rathmann@fz-juelich.de
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 COSYf.rathmann@fz-juelich.de
Search for Permanent Electric Dipole Moments at COSY 4
A 1: Spin coherence time
f.rathmann@fz-juelich.de
Sextupole corrections of higher order effects yield
Search for Permanent Electric Dipole Moments at COSY 5
A 2: Spin tune determination
f.rathmann@fz-juelich.de
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.
Search for Permanent Electric Dipole Moments at COSY 6
A 3: Harmonic dependence of
f.rathmann@fz-juelich.de
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
Search for Permanent Electric Dipole Moments at COSY 7
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)
f.rathmann@fz-juelich.de
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
Search for Permanent Electric Dipole Moments at COSY 8
First 2-D Map: vs MXS vs MXG
f.rathmann@fz-juelich.de
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.
Search for Permanent Electric Dipole Moments at COSY 9
Chromaticity studies (tests in week 7)
f.rathmann@fz-juelich.de
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
f.rathmann@fz-juelich.de Search for Permanent Electric Dipole Moments at COSY 10
Search for Permanent Electric Dipole Moments at COSY 11
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: / /
f.rathmann@fz-juelich.de
Search for Permanent Electric Dipole Moments at COSY 12
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
f.rathmann@fz-juelich.de
Straight section sextupoles show no effect on chromaticity
Search for Permanent Electric Dipole Moments at COSY 13f.rathmann@fz-juelich.de
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
Search for Permanent Electric Dipole Moments at COSY 14
2. RF Wien Filter
f.rathmann@fz-juelich.de
Precursor EDM concept: Use RF Wien filter to accumulate EDM signal
Insert RF-dipole into ceramic chamber
Search for Permanent Electric Dipole Moments at COSY 15f.rathmann@fz-juelich.de
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
Search for Permanent Electric Dipole Moments at COSY 16f.rathmann@fz-juelich.de
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
Search for Permanent Electric Dipole Moments at COSY 17
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.
f.rathmann@fz-juelich.de
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.
Search for Permanent Electric Dipole Moments at COSY 18
Imperfection kick: Deuterons at MeV
f.rathmann@fz-juelich.de
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:
Search for Permanent Electric Dipole Moments at COSY 19
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.
f.rathmann@fz-juelich.de
Search for Permanent Electric Dipole Moments at COSY 20
Backup slides
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21f.rathmann@fz-juelich.de Search for Permanent Electric Dipole Moments at COSY
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
f.rathmann@fz-juelich.de Search for Permanent Electric Dipole Moments at COSY 22
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
f.rathmann@fz-juelich.de Search for Permanent Electric Dipole Moments at COSY 23
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
f.rathmann@fz-juelich.de Search for Permanent Electric Dipole Moments at COSY 24
Radial E and vertical B fields oscillate, e.g., with (here ).
beam energy
Spin coherence time may depend on excitation and on harmonics .𝐾
f.rathmann@fz-juelich.de Search for Permanent Electric Dipole Moments at COSY 25
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 .
Search for Permanent Electric Dipole Moments at COSY 26
Development: RF E/B-Flipper (RF Wien Filter)
f.rathmann@fz-juelich.de
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)
27f.rathmann@fz-juelich.de Search for Permanent Electric Dipole Moments at COSY
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
Search for Permanent Electric Dipole Moments at COSY 28
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.
f.rathmann@fz-juelich.de
Search for Permanent Electric Dipole Moments at COSY 29
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
f.rathmann@fz-juelich.de
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
f.rathmann@fz-juelich.de
Search for Permanent Electric Dipole Moments at COSY 31
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
f.rathmann@fz-juelich.de
Search for Permanent Electric Dipole Moments at COSY 32
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
f.rathmann@fz-juelich.de
33
Charge symmetric No EDM ()
Do particles (e.g., electron, nucleon) have an EDM?
f.rathmann@fz-juelich.de Search for Permanent Electric Dipole Moments at COSY
: MDM: EDM
Physics: Fundamental Particles
Search for Permanent Electric Dipole Moments at COSY 34
Physics: Symmetries
Parity:
f.rathmann@fz-juelich.de
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
f.rathmann@fz-juelich.de 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.“
f.rathmann@fz-juelich.de Search for Permanent Electric Dipole Moments at COSY
Physics: Potential of EDMs
f.rathmann@fz-juelich.de 37Search for Permanent Electric Dipole Moments at COSY
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
f.rathmann@fz-juelich.de 38Search for Permanent Electric Dipole Moments at COSY
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
39f.rathmann@fz-juelich.de Search for Permanent Electric Dipole Moments at COSY
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 COSYf.rathmann@fz-juelich.de
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
41f.rathmann@fz-juelich.de Search for Permanent Electric Dipole Moments at COSY
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
Search for Permanent Electric Dipole Moments at COSY 42f.rathmann@fz-juelich.de
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
f.rathmann@fz-juelich.de 43Search for Permanent Electric Dipole Moments at COSY
Challenge: Spin coherence time
Spin closed orbit
Challenge: Spin coherence time
f.rathmann@fz-juelich.de Search for Permanent Electric Dipole Moments at COSY 44
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)
f.rathmann@fz-juelich.de Search for Permanent Electric Dipole Moments at COSY 45
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
f.rathmann@fz-juelich.de 46Search for Permanent Electric Dipole Moments at COSY
… an ideal starting pointfor a srEDM search
Search for Permanent Electric Dipole Moments at COSY 47
New Idea: Ivan Koop‘s spin wheel
f.rathmann@fz-juelich.de
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.
Search for Permanent Electric Dipole Moments at COSY 48
How Ivan‘s spin wheel would work?
f.rathmann@fz-juelich.de
Frequency
B field
EDM =0
EDM ≠ 0
∼ ⟨ Δ 𝑦 ⟩
Find the value of B wherespin precession frequency
disappears
Search for Permanent Electric Dipole Moments at COSY 49
SQUIDs: Precision tools for accelerators
f.rathmann@fz-juelich.de
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
Search for Permanent Electric Dipole Moments at COSY 50
New Idea: Direct measurement of electron EDM
f.rathmann@fz-juelich.de
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
f.rathmann@fz-juelich.de Search for Permanent Electric Dipole Moments at COSY 51
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”
f.rathmann@fz-juelich.de Search for Permanent Electric Dipole Moments at COSY