search for permanent electric dipole moments of protons
TRANSCRIPT
Mitg
lied
de
r H
elm
ho
ltz-
Ge
me
insch
aft
Search for permanent electric dipole moments
of protons and deuterons using storage rings
February 4, 2016 Frank Rathmann (on behalf of JEDI)
Accelerator Seminar, Jefferson Lab
Preamble: The big challenges
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This is the conventional HEP wisdom, but there is more than that โฆ
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Search for
the origin of
mass (โHiggsโ),
SUSY
Secrets of
neutrinos
Quest for
โDark Matterโ
and
โDark Energyโ (In-)stability
of the
proton
Precision
Preamble: Physics Frontiers
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A most promising additional frontier: Precision
ESPP, Cracow,
September 2012
Preamble: Precision Frontier
Outline
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โข Introduction
โข Recent Achievements
โข Spin coherence time
โข Spin tune measurement
โข Study of magnetic machine imperfections
โข Technical challenges
โข Toward a first direct ๐, ๐ EDM measurement
โข Conclusion
Introduction: Precision Frontier
Striving for the ultimate precision/sensitivity: example hydrogen
Johann
Jakob
Balmer
(1885)
Balmer
Series
H-atom
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Introduction: Precision Frontier
Striving for the ultimate precision/sensitivity
Balmer
Series
H-atom
Johann
Jakob
Balmer
(1885)
Willis E.
Lamb
(1947)
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Lamb-shift
(NP 1955)
QED
g/2 = 1 + a/2p
~ 1.00116
Introduction: Precision Frontier
V. Weisskopf: โTo understand hydrogen is to understand all of physicsโ
Balmer
Series
H-atom
Electron MDM
SM test G. Gabrielse
et al. (2008)
Johann
Jakob
Balmer
(1885)
(โฆ)
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Five questions:
1. Why do we observe matter and almost no antimatter if
we believe there is a symmetry between the two in the
universe?
2. What is this "dark matter" that we can't see that has
visible gravitational effects in the cosmos?
3. Why can't the Standard Model predict a particle's mass?
4. Are quarks and leptons actually fundamental, or made up
of even more fundamental particles?
5. Why are there exactly three generations of quarks and
leptons? How does gravity fit into all of this?
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From http://particleadventure.org/beyond_start.html
Assertion: Universe โstartedโ with equal amounts of matter and antimatter !
Early
Universe
Big
Bang
Physics: Baryogenesis
Matter Anti-matter
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Very soon, a slight asymmetry developed (CP / T violation)
Early
Universe
Matter Anti-matter
Big
Bang
Physics: Baryogenesis
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All the anti-matter annihilated with matter
Early
Universe
Matter Anti-matter
Big
Bang
Physics: Baryogenesis
Matter
anti-matter
annihilation
photons
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Now, only matter is left over !
Early
Universe
Today
Matter Anti-matter
Matter
anti-matter
annihilation
photons
Big
Bang
Physics: Baryogenesis
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Physics: Baryogenesis
Ingredients for baryogenesis: 3 Sakharov conditions
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(1967)
Physics: Observed Baryon Asymmetry
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Carina Nebula: Largest-seen star-birth regions in the galaxy
(๐๐ตโ๐๐ต )/๐๐พ
Observed (6.11 ยฑ 0.19) ร 10โ10 WMAP+COBE (2003)
SM exp. ~10โ18
โข Search for new physics beyond the standard model
โข Mystery of missing antimatter addresses the puzzle of our existence
Why this strange number? Why not zero?
Charge symmetric
No EDM (๐ = ๐)
Do particles (e.g., electron, nucleon) have an EDM?
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: MDM
๐ : EDM
Physics: Fundamental Particles
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Permanent EDMs violate both ๐ท and ๐ป symmetry.
Assuming ๐ช๐ท๐ป to hold, ๐ช๐ท violated also.
Not Charge
symmetric ๐ (aligned with spin)
EDMs: Discrete Symmetries
Search for Electric Dipole Moments (EDM) of fundamental particles
Adapted from: Nature,
Vol 482 (2012)
Example: Neutron (nEDM)
Introduction: Precision Frontier
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An EDM is VERY small !!
Current upper limit โ
separation โ size of a hair
Nucleon Earth
1 fm
Introduction: Precision Frontier
๐๐๐๐ fm
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Measurement principle: Neutral particle EDM
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Particle in ground state: ๐ =๐
๐
๐
๐๐
๐ฉ ๐ฌ
๐1 =2๐๐ต + 2๐๐ธ
โ
๐
๐๐
๐ฉ ๐ฌ
๐2 =2๐๐ต โ 2๐๐ธ
โ
โ ๐1 โ ๐2 =4๐๐ธ
โ
1. Reverse ๐ธ
2. Keep ๐ต the same
One challenge: Shield external sources of B to levels ๐ตext < 1 nT.
J.M. Pendlebury: โnEDM has killed more theories than any other single expโtโ
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Physics Potential of EDMs
โ ๐ (๐ฉ๐ซ๐จ๐ญ๐จ๐ง) < ๐ โ ๐๐โ๐๐
โ ๐ (๐๐ฅ๐๐๐ญ๐ซ๐จ๐ง) < ๐ โ ๐๐โ๐๐
โ ๐ (๐ง๐๐ฎ๐ญ๐ซ๐จ๐ง) < ๐ โ ๐๐โ๐๐
Introduction: Why charged particle EDMs?
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โข No direct measurements of charged hadron EDMs
โข Potentially higher sensitivity than neutrons
โข longer life time
โข more stored polarized protons/deuterons
โข larger electric fields
โข Approach complimentary to neutron EDM
โข ๐๐ = ๐๐ + ๐๐ โ access to ๐๐๐ถ๐ท
โข EDM of a single particle not sufficient to identify CP-
violating source
Charged particle EDM experiments can potentially
provide a higher sensitivity than nEDM
?
EDMs: Naive estimate of the nucleon EDM scale
โข ๐ช๐ท & ๐ท conserving magnetic moment โ nuclear magneton ๐๐ต
๐๐ =๐
2๐๐~10โ14e cm
โข A non-zero EDM requires
โข ๐ violation: the price to pay is โ 10โ7, and
โข ๐ถ๐ violation (from K-decays): the price to pay is โ 10โ3
โข In summary:
โข In SM (without ๐ term):
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Khriplovich & Lamoreux (1997); Nikolaev (2012)
โ Region to search for BSM physics ๐QCD = 0 using nucleon EDMs:
๐๐โ๐๐๐ ๐๐ฆ > ๐ ๐ต > ๐๐โ๐๐ ๐ ๐๐ฆ
๐ ๐ต โ ๐๐โ๐ ร ๐๐โ๐ ร ๐๐ต โ ๐๐โ๐๐ ๐ ๐๐ฆ
๐ ๐ต๐๐ โ ๐๐โ๐ ร ๐๐โ๐๐ โ ๐๐โ๐๐ ๐ ๐๐ฆ
EDM searches: Up to now only upper limits (in ๐๐๐ฆ)
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Particle/Atom Current EDM Limit Future Goal
Electron < 8.7 โ 10โ29
Muon < 1.8 โ 10โ19
Neutron 3 โ 10โ26 10โ28
๐๐๐๐๐ 3.1 โ 10โ29 10โ29
๐๐๐๐๐ 6 โ 10โ27 10โ30 โ 10โ33
Proton 7.9 โ 10โ25 10โ29
Deuteron ? 10โ29
Physics: Present limits of EDMs
Large effort on worldwide scale to improve limits and to find EDMs
โข No direct measurements of electron (ThO molecule) or proton ( Hg199 ) EDMs
โข No measurement at all of deuteron EDM
P. Harris, K. Kirch โฆ A large worldwide effort
new
Physics: Ongoing/planned Searches
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Goal: provide ๐syst to the same level
๐๐ฌ๐ญ๐๐ญ โ๐
๐ต โ ๐ โ ๐ โ ๐ท โ ๐จ๐ โ ๐ฌ โ ๐๐๐๐๐ ๐ ๐ฒ๐๐๐ซ = ๐๐โ๐๐ ๐ โ ๐๐ฆ
โข High precision, primarily electric storage ring
โข alignment, stability, field homogeneity, and shielding from
perturbing magnetic fields
โข High beam intensity (๐ = 4 โ 1010 per fill)
โข Stored polarized hadrons (๐ = 0.8)
โข Large electric fields (๐ธ = 10 MV/m)
โข Long spin coherence time (๐SCT = 1000 s)
โข Efficient polarimetry (analyzing power ๐ด๐ฆ โ 0.6, ๐ = 0.005)
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Concept: Experimental requirements
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For transverse electric and magnetic fields in a ring, the
anomalous spin precession is described by Thomas-BMT equation:
Magic condition: Spin along momentum vector
1. For any sign of ๐บ, in a combined electric and magnetic machine
๐ธ =๐บ๐ต๐๐ฝ๐พ2
1โ๐บ๐ฝ2๐พ2 โ ๐บ๐ต๐๐ฝ๐พ2, where ๐ธ = ๐ธradial and ๐ต = ๐ตvertical
2. For ๐บ > 0 (protons) in an all electric ring
๐บ โ๐
๐
2= 0 โ ๐ =
๐
๐บ= 700.74 MeV/c (magic)
Concept: Frozen spin Method
Magic rings to measure EDMs of free charge particles
ฮฉMDM =๐
๐๐บ โ ๐ต โ
๐พ๐บ
๐พ + 1๐ฝ ๐ฝ โ ๐ธ โ ๐บ โ
1
๐พ2 โ 1
๐ฝ ร ๐ธ
๐ ๐บ =
๐ โ 2
2
โข Place particles in a storage ring
โข Align spin along momentum (โfreezeโ horizontal spin precession)
โข Search for time development of vertical polarization
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Concept: Rings for EDM searches
New Method to measure EDMs of charged particles:
โข Magic rings with spin frozen along momentum
โข Polarization buildup ๐ท๐ (๐) ~ ๐
๐๐บ = 0
๐๐
๐๐ก= ๐ ร ๐ธ
A magic storage ring for protons (electrostatic), deuterons, โฆ
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particle ๐ (๐๐๐/๐) ๐ป (๐๐๐) ๐ฌ (๐๐/๐ฆ) ๐ฉ (๐)
proton ๐๐๐ ๐๐๐. ๐ ๐๐. ๐๐๐ ๐. ๐๐๐
Concepts: Magic Storage ring
Possible to measure ๐, ๐ , ๐๐๐ using one machine with ๐ ~ 25 m
B
deuteron ๐๐๐๐ ๐๐๐. ๐ โ๐. ๐๐๐ ๐. ๐๐๐
๐๐๐ ๐๐๐๐ 280.0 ๐๐. ๐๐๐ โ๐. ๐๐๐
๐๐บ = 0
๐๐
๐๐ก= ๐ ร ๐ธ
Magnetic fields:
โข Radial field ๐ต๐ mimics EDM effect when ๐ ร ๐ต๐ โ ๐ ร ๐ธ๐
โข With ๐ = 10โ29 e โ cm in a field of ๐ธ = 10 MV/m,
๐ต๐ =๐๐ธ๐
๐๐=
10โ31โ107eV
3.152โ10โ8 eV/T= 3.1 โ 10โ17 T
โข Solution: Use two beams simultanously, clockwise (CW)
and counter-clockwise (CCW), the vertical separation of
the beam orbits is sensitive to ๐ต๐.
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Concept: Systematics
Use CW and CCW beams to tackle systematics
Recent Progress: Magnetic shielding
Next generation nEDM experiment under development at TUM (FRM II):
โข Goal: Improve present nEDM limit by factor 100.
โข Experiment shall use multi-layer shield.
โข Applied magnetic field: B โ 1โ2.5 ๐T.
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J. Appl. Phys. 117 (2015)
At mHz frequencies, damping of ๐ตext โ 1 โ 106 achieved
โข Splitting of beam orbits: ๐ฟ๐ฆ = ยฑ๐ฝ๐๐ 0๐ต๐
๐ธ๐๐๐ฆ2 = ยฑ1 โ 10โ12 m
โข ๐๐ฆ โ 0.1 denotes the vertical betatron tune
โข Modulate ๐๐ฆ = ๐๐ฆ0 1 โ ๐ cos ๐๐๐ก , with ๐ โ 0.1
โข Splitting corresponds to ๐ต โ 0.4 โ 10โ3 fT
โข In one year of measurement: 104 fills of 1000 s each
โ ๐๐ต = 0.4 โ 10โ1fT per fill
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Concept: Systematics, Orbit splitting (Dave Kawall)
Required sensitivity โ 1.25 fT Hz , achievable
with state-of-the-art SQUID magnetometers.
Outline
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โข Introduction
โข Recent Achievements
โข Spin coherence time
โข Spin tune measurement
โข Study of magnetic machine imperfections
โข Technical challenges
โข Toward a first direct ๐, ๐ EDM measurement
โข Conclusion
A
AS
one particle with
magnetic moment
โspin tuneโ
โspin closed orbit vectorโ COnฬ
sp2AS
ring
makes one turn
stable polarization S
if โ COnฬ
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Insert: Spin closed orbit and spin tune
Spin closed orbit
= 2๐๐พ๐บ
The number of spin precessions per turn is called spin tune ๐๐
Challenge: Spin coherence time (SCT)
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We usually donโt worry about coherence of spins along ๐ ๐๐
At injection all
spin vectors aligned (coherent)
After some time, spin vectors get out of
phase and fully populate the cone
Polarization along
๐ ๐๐ not affected!
Situation very different, when you deal with ๐ โฅ ๐ ๐๐ machines with frozen spin.
At injection all spin vectors aligned Later, spin vectors are out of
phase in the horizontal plane
Longitudinal polarization
vanishes!
COnฬ
In a machine with frozen spins the buildup time
to observe a polarization ๐ท๐ ๐ is limited by ๐๐๐๐.
EDM at COSY: COoler SYnchrotron
Cooler and storage ring for (polarized) protons and deuterons
๐ = ๐. ๐ โ ๐. ๐ ๐๐๐/๐
Phase space
cooled internal &
extracted beams
Injector cyclotron
COSY
โฆ the spin-physics machine
for hadron physics
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โฆ an ideal starting point
for EDM search
Outline
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โข Introduction
โข Recent Achievements
โข Spin coherence time
โข Spin tune measurement
โข Study of magnetic machine imperfections
โข Technical challenges
โข Toward a first direct ๐, ๐ EDM measurement
โข Conclusion
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turn spin
free precession
polarimeter
Spin coherence time: Experimental investigation
1. Vertically polarized deuterons stored in COSY at ๐ โ 1GeV
c.
2. The polarization is flipped into horizontal plane with RF solenoid (takes โ 200 ms).
3. Beam slowly extracted on Carbon target with ramped bump or by heating the beam.
4. Horizontal (in-plane) polarization determined from Up-Do asymmetry in the detector.
Experimental investigations of SCT in storage ring: Keep track of the event time
and revolution time in each turn during a cycle of a few hundred seconds.
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Spin coherence time: Beam setups
Two different beam setups were used:
1. Large โ๐
๐ , and
2. large horizontal beam emittance.
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Polarimeter: Experimental investigation of SCT
๐๐,๐ท โ 1 ยฑ3
2๐ โ ๐ด๐ฆ โ sin ๐๐ ๐rev๐ก , where ๐rev โ 781 ๐๐ป๐ง
Deuterons at ๐ โ 1 GeV/c, ๐พ = 1.13 and ๐๐ = ๐พ โ ๐บ = โ0.161
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Polarimeter: Determination of SCT
Observed experimental decay of the asymmetry ํ๐๐ท =๐๐ทโ๐๐
๐๐ท+๐๐
as function of time, ํ๐๐ท(๐ก) โ ๐(๐ก).
๐๐๐๐ โ ๐๐ ๐ฌ
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Polarimeter: Optimization of SCT
Using sextupole magnets in the machine, higher order effects can be
corrected, and the SCT is substantially increased
๐๐๐๐ โ ๐๐๐ ๐ฌ
SCT: Chromaticity studies
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Maximal horizontal polarization lifetimes from
scans with a horizontally wide or a long
beam agree well with the lines of ๐๐ฅ,๐ฆ โ 0.
Chromaticity ๐ defines the betatron tune change with respect to the
momentum deviation
ฮ๐๐ฅ,๐ฆ
๐๐ฅ,๐ฆ= ๐๐ฅ,๐ฆ โ
ฮ๐
๐
โข Strong connection between
๐๐ฅ,๐ฆ and ๐๐๐ถ observed.
โข COSY Infinity based model predicts
negative natural chromaticities ๐๐ฅ and ๐๐ฆ.
โข Measured natural chromaticity:
๐๐ฆ > 0 and ๐๐ฅ < 0.
Crucial for achieving a large ๐๐๐ถ is careful adjustment of ๐๐ฅ,๐ฆ.
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More progress on ๐๐๐๐: Spring 2015
Way beyond anybodyโs expectations โ ๐๐ฌ๐ญ๐๐ญ โ ๐๐๐๐โ๐
Outline
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โข Introduction
โข Recent Achievements
โข Spin coherence time
โข Spin tune measurement
โข Study of magnetic machine imperfections
โข Technical challenges
โข Toward a first direct ๐, ๐ EDM measurement
โข Conclusion
Spin tune ๐๐: How to m๐๐๐ฌ๐ฎ๐ซ๐ ๐ข๐ญ?
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Solution: Map all events into one spin oscillation period
๐๐ โก Number of spin precessions revolution, a priori not known (โ ๐พ๐บ)
โข Detector rate is โ 5 kHz, ๐rev = 781 kHz โ one hit in detector per
25 beam revolutions
๐๐๐โ ๐๐โ๐
Scan ๐๐ in an interval around ๐พ๐บ and find maximum of asymmetry ํ๐๐ท
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Spin tune: D๐๐ญ๐๐ซ๐ฆ๐ข๐ง๐๐ญ๐ข๐จ๐ง ๐จ๐ ๐๐
Spin tune ๐๐ determined to โ 10โ8 in 2 s time interval,
and in a 100 s cycle at ๐ก โ 40 s to โ 10โ10 (PRL 115, 094801 (2015)
Monitor phase of asymmetry
with fixed ๐๐ in a 100 s cycle.
๐๐ ๐ = ๐๐ fix +
1
2๐
d๐ (๐)
d๐
= ๐๐ fix + ฮ๐๐ (๐)
New precision tool: Spin tune determination
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โข Study long term stability of an accelerator
โข Develop feedback systems to minimize variations
โข Phase-locking the spin precession to RF devices possible
Observed behavior of subsequent cycles
Outline
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โข Introduction
โข Recent Achievements
โข Spin coherence time
โข Spin tune measurement
โข Study of magnetic machine imperfections
โข Technical challenges
โข Toward a first direct ๐, ๐ EDM measurement
โข Conclusion
Systematic study: Machine imperfections
using two straight section solenoids
Idea: The precise determination of the spin tune ฮ๐๐
๐๐ โ 10โ10 in one cycle
can be exploited to map out the magnetic 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:
๐ฉ๐๐ ๐ โ ๐. ๐๐ ๐๐ฆ,
2. The main solenoid of the 2 MV cooler: ๐ฉ๐๐ ๐ โ ๐. ๐๐ ๐๐ฆ.
Both are available dynamically in the cycle, i.e., their strength can be
adjusted on flat top.
Systematic effects from machine imperfections limit the achievable
precision in an EDM experiment using an RF E ร B Wien filter.
Systematic study: Simulation of one
imperfection spin kick for deuterons at ๐๐๐ MeV/c
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Ideal machine with vanishing static
imperfections: Saddle point at the origin
sea level at ๐บ๐พ (= 0.16) โ 5 โ 10โ7
Intrinsic imperfection kick ๐ผ๐ฅ = 0.001 shifts saddle point away from origin
Location of imperfection: ฮโ = ๐ 3
Systematic study: Thomas-BMT eq. (๐ โ 0) in magnetic machine
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ฮฉMDM =๐
๐๐บ โ ๐ต โ
๐พ๐บ
๐พ + 1๐ฝ ๐ฝ โ ๐ธ โ ๐บ โ
1
๐พ2 โ 1
๐ฝ ร ๐ธ
๐
ฮฉEDM =๐๐
2๐๐๐ธ โ
๐พ
๐พ + 1๐ฝ ๐ฝ โ ๐ธ + ๐๐ฝ ร ๐ต
๐๐
๐๐ก= ๐ ร ฮฉMDM + ฮฉEDM
๐ = ๐๐โ
2๐๐ = ๐บ + 1
๐โ
๐๐ , and ๐ =
๐๐โ
2๐๐
BMT for magnetic machine with ๐ โ 0: ๐๐
๐๐ก=
๐
๐๐บ โ ๐ต +
๐
2๐ฝ ร ๐ต
Interaction of EDM with motional E-field (๐ฝ ร ๐ต) tilts stable spin axis:
๐๐๐ = ๐ ๐ฅ sin ๐ + ๐ ๐ฆ cos ๐ tan ๐ =๐
2๐บ๐ฝ ๐ = 2๐
๐
๐
Goal: explore dynamics and systematic limitations of EDM searches in magnetic ring
Misalignment of magnetic elements produces in-plane imperfection magnetic fields:
๐๐๐ = ๐ ๐ฅ๐1 + ๐ ๐ฆ๐2 + ๐ ๐ง๐3
Non-vanishing ๐1 and ๐3 generate background to the EDM-signal of an ideal
imperfection-free machine (๐1 = sin ๐, ๐2 = cos ๐ and ๐3 = 0).
The challenge is to control this background:
An accuracy โ๐1,3 โ 10โ6 rad amounts to a sensitivity ๐ = 10โ20 e โ cm.
[email protected] Search for permanent Electric Dipole Moments using storage rings 53
Systematic study: Imperfection measurement
Probing the in-plane imperfection fields by introducing artificial imperfections and
looking for the spin tune response
The values of (๐1, ๐2), and ๐3, ๐3โ depend of spin kicks in non-vertical
imperfection fields in the arcs โ spin tune perturbed:
๐๐ = ๐บ๐พ + ๐(๐12, ๐3
2, ๐1โ2, ๐3
โ2)
๐ ๐ฅ๐1 + ๐ ๐ฆ๐2 + ๐ ๐ง๐3 = ๐๐๐
๐๐๐โ= ๐ ๐ฅ๐1
โ + ๐ ๐ฆ๐2โ + ๐ ๐ง๐3
โ
Use the compensation and e-cooler solenoids
in straight sections (points 1 and 2):
spin kicks ๐1 and ๐2.
Probe the in-plane imperfection fields by introducing well-known artificial
imperfections ๐1 and ๐2.
[email protected] Search for permanent Electric Dipole Moments using storage rings 54
Systematic study: Measurement of spin tune shift
Take multiple measurements with different ๐1, ๐2, build a spin tune map ฮ๐๐ (๐1, ๐2)
[email protected] Search for permanent Electric Dipole Moments using storage rings 55
Systematic study: Mapping machine
imperfections Map translated to
๐ฆ+ =๐1 + ๐2
2
๐ฆโ =๐1 โ ๐2
2
ฮ๐๐ โ ๐ฆ+2, ๐ฆโ
2 โ
โ
โ
โ
From the map taken on 18+19.09.2014, with the baseline spin tune at
๐๐ = โ0.160971917, one finds: ๐3 = โ0.0034 ยฑ 2 โ 10โ7
๐3โ = โ0.0021 ยฑ 6 โ 10โ8.
Fit map to locate
saddle point
[email protected] Search for permanent Electric Dipole Moments using storage rings 56
Systematic study: Mapping imperfections
Map translated to
๐ฆ+ =๐1 + ๐2
2
๐ฆโ =๐1 โ ๐2
2
ฮ๐๐ โ ๐ฆ+2, ๐ฆโ
2 โ
โ
โ
โ
New technique allows one to experimentally reconstruct the components of
the spin closed orbit ๐๐๐ in a storage ring with unprededented precision
(not achievable from polarization measurements alone).
โข Extremum of spin tune map is saddle point at ๐ฆ+, ๐ฆโ = ๐(๐3, ๐3โ).
โข Once baseline spin tune ๐๐ determined, (๐3, ๐3โ) are only fit parameters.
โข Solenoids only are not sensitive to ๐1, ๐1โ (โ static WF with ๐ต๐ฅ and ๐ธ๐ฆ).
Outline
[email protected] Search for permanent Electric Dipole Moments using storage rings 57
โข Introduction
โข Recent Achievements
โข Spin coherence time
โข Spin tune measurement
โข Study of magnetic machine imperfections
โข Technical challenges
โข Beam position monitors
โข Electrostatic deflectors
โข Toward a first direct ๐, ๐ EDM measurement
โข Conclusion
[email protected] Search for permanent Electric Dipole Moments using storage rings 58
Charged particle EDM searches require the development of a new
class of high-precision machines with mainly electric fields for
bending and focussing.
Issues are:
โข Electric field gradients ~17 MV
m at ~2 cm plate distance
โข Spin coherence time (โฅ 1000 s)
โข Continuous polarimetry < 1 ppm
โข Beam position monitoring 10 nm
โข Spin tracking
These issues must be addressed experimentally at existing facilities
Technical challenges: Overview
[email protected] Search for permanent Electric Dipole Moments using storage rings 59
Challenge BPMs: Rogowski coil
For bunched beams, sum signal of Rogowski coil can be used as a beam current monitor.
Installed in ANKE
target chamber
Readout
Rogowski coil
BCT
Bunched
beam
โข Integral signal measures beam current
โข Quadrant signals sensitive to position
[email protected] Search for permanent Electric Dipole Moments using storage rings 60
EDM experiments use bunched beams:
โข Rogowski coil system well-suited.
โข Small size allows for flexible installation (โ Stripline RF Wien filter)
Quadrant signals of Rogowski coil sensitive to beam position.
Tests at COSY can be carried out parasitically.
โข Integral signal measures beam current
โข Quadrant signals sensitive to position
Challenge BPMs: Rogowski coil
๐ฅ =left โ right
left + right
๐ฆ =up โ down
up + down
left right
down
up
Dynamic range
โข 108 โ 1011 particles
โข Maximum deviation from axis โ 40 mm
โข Resolution: 10 nm
[email protected] Search for permanent Electric Dipole Moments using storage rings 61
Challenge: Niobium electrodes
Large-grain Nb at plate separation of a few cm yields ~20 MV/m
Show one slide on JLAB data HV devices
DPP stainless steel fine-grain Nb
large-grain Nb large-grain Nb single-crystal Nb
[email protected] Search for permanent Electric Dipole Moments using storage rings 62
Challenge: Electric deflectors for magic rings
Electrostatic separators at Tevatron were used to avoid unwanted ๐ ๐
interactions - electrodes made from stainless steel
Routine operation at 1 spark/year at 6 MV/m
Need to develop new electrode materials and surface treatments
May 2014: Transfer of separator unit plus equipment from FNAL to Jรผlich
[email protected] Search for permanent Electric Dipole Moments using storage rings 63
1. Deflector development will use scaled models ~ 1: 10
โข Electric fields are the same, but voltages < 20 kV
โข Avoids shielding of x-rays
โข Allows tests to be done in usual lab environment
2. Development of real size combined elements (E & B)
โข Begin EDM search with deuterons
โข Use existing dipole magnet of internal ANKE spectrometer
โข Allows for tests with beam
Challenge: Electric deflectors for magic rings
Development of new deflector materials, treatment methods towards
high fields ๐ธ~20 MV/m, and combined E-B deflectors
Electrostatic deflectors: Clean room at RWTH
Prof. Marquardt chairman of FZJ directors board and Prof. Schmachtenberg Rektor of RWTH Aachen
Test bench at RWTH Aachen
[email protected] Search for permanent Electric Dipole Moments using storage rings 64
Development of mall scale deflector elements in cooperation with RWTH (Kirill Grigoriev).
But: Result need to be verified using 1:1 deflector models (Jรผlich)
Different shape of the electrodes
Material : Stainless steel, Aluminum
Mechanical polished and cleaned
Stainless steel
Two small half-spheres (R = 10mm)
17kV at 1mm distance โ 17 MV/m
Half-sphere vs. flat surface
12kV at 0.05 mm distance โ 240 MV/m
Aluminum
Two small half-spheres (R = 10mm)
3kV at 0.1mm distance โ 30 MV/m
Electrostatic deflectors: Some results
Large scale elements: ANKE chicane at COSY
[email protected] Search for permanent Electric Dipole Moments using storage rings
Idea (Jรผrgen Bรถker): Produce E-B deflector by insertion of
deflector element into D2 magnet chamber.
Large-scale E-B deflector development
[email protected] Search for permanent Electric Dipole Moments using storage rings 67
D2 magnet:
Bmax = 1.6 T,๐
= 64 t
Actuators
Feed-Throughs Deflector
Deflector: Length: 1020 mm, Height: 90 mm, Gap: 40 โ 80 mm
Begin development with straight elements
Outline
[email protected] Search for permanent Electric Dipole Moments using storage rings 68
โข Introduction
โข Recent Achievements
โข Spin coherence time
โข Spin tune measurement
โข Study of magnetic machine imperfections
โข Technical challenges
โข Toward a first direct ๐, ๐ EDM measurement
โข Conclusion
[email protected] Search for permanent Electric Dipole Moments using storage rings 69
Use COSY for a first direct ๐ and ๐ EDM measurement
Use an RF technique:
โข RF device operates on some harmonic of the
spin precession frequency
โข accumulate EDM signal with time
Idea for proof-of-principle srEDM experiment
[email protected] Search for permanent Electric Dipole Moments using storage rings 70
Direct EDM measurement :
Resonance Method with โmagicโ 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.
๐ฌโ = ๐ ๐ฌ๐น = โ๐ฉ๐ โMagic RF Wien Filterโ no Lorentz force
โ 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 ๐ ๐ in the range ๐๐โ๐๐ to ๐๐โ๐๐ ๐๐๐ฆ range possible.
โข Alignment and field stability of ring magnets
โข Imperfection of RF-E(B) flipper
[email protected] Search for permanent Electric Dipole Moments using storage rings 71
First direct EDM measurement:
Resonance Method for deuterons
Parameters: beam energy ๐๐ = 50 MeV ๐ฟRF = 1 m
assumed EDM ๐๐ = 10โ24 ecm
E-field 30 kV/cm
๐ = 2๐๐๐๐๐ฃ๐บ๐พ = โ3.402 ร 105 Hz
๐ญ๐ฎ๐ซ๐ง ๐ง๐ฎ๐ฆ๐๐๐ซ
๐ท๐ ๐ท๐ ๐ท๐
EDM effect accumulates in ๐๐ฆ (see Phys. Rev. ST AB 16, 114001 (2013))
[email protected] Search for permanent Electric Dipole Moments using storage rings 72
Parameters: beam energy ๐๐ = 50 MeV ๐ฟRF = 1 m
assumed EDM ๐๐ = 10โ24 ecm
E-field 30 kV/cm
EDM effect accumulates in ๐๐ฆ
๐๐ฆ
๐ญ๐ฎ๐ซ๐ง ๐ง๐ฎ๐ฆ๐๐๐ซ
๐ท๐
Linear extrapolation of ๐ท๐ for a time period of
๐ ๐ = 1000 s (= 3.7108 turns) yields a sizeable ๐ท๐~๐๐โ๐.
First direct Edm measurement:
Resonance Method for deuterons
[email protected] Search for permanent Electric Dipole Moments using storage rings 73
RF ๐ ร ๐ Wien Filter: Resonance condition
Deuterons at 970 MeV/c: ฮฒ = 0.459; ฮณ = 1.126; ๐บ = โ0.142 987
๐๐ ๐น = ๐rev(๐พ๐บ ยฑ ๐พ), ๐พ โ โค ๐rev โ 750 kHz
๐๐ = ๐พ๐บ = โ0.16098
๐พ 0 1 โ1 2 โ2
๐๐ ๐น/kHz 120 629 871 1380 1621
Frequency range RF Wien filter prototype
RF ๐ ร ๐ Wien Filter: Prototype commissioning
[email protected] Search for permanent Electric Dipole Moments using storage rings 74
EDM measurement concept: RF Wien filter to accumulate EDM signal
Insert RF-๐ฌ๐ dipole into ceramic
chamber
[email protected] Search for permanent Electric Dipole Moments using storage rings 75
RF ๐ ร ๐ Wien Filter: Field calculations
๐ (๐ฆ)
๐ฉ๐ (๐)
Main field component
๐ต ๐ฅ = 0.058 mT at ๐ฆ = 0, ๐ผ = 1 A,
๐ฉ ๐๐ ๐ = ๐. ๐๐๐ ๐๐ฆ๐ฆ
Main field component
๐ธ ๐ฆ = 7594 V/m at y = 0,
U = 395 V, ๐ฌ ๐๐ ๐ = ๐๐๐๐ ๐
๐ (๐ฆ)
๐ฌ๐ (๐/๐ฆ
)
๐ (๐ฆ) ๐ญ
๐ (๐๐/๐ฆ
)
Integral compensation of Lorentz
force ๐น๐ฆ๐๐ง = 0 at y = 0
[email protected] Search for permanent Electric Dipole Moments using storage rings 76
RF Wien Filter: Measurement of Resonance Strengths
โข Continuous polarimetry: Fixed
frequency scans for resonance
determination
โข Damping due to decoherence
โข Cross-ratio of UD-asymmetries used.
โข Minimum vertical polarization
oscillation frequency gives resonance
strength:
๐ =๐๐๐ฆ,min
๐rev
871.4276 871.4276 871.4276
๐๐ ๐น kHz
0.20
0.25
0.30
0.35
Spin
osc
illation fre
quen
cy kHz
[email protected] Search for permanent Electric Dipole Moments using storage rings 77
RF ๐ ร ๐ Wien Filter: Preliminary Results
RF solenoid:
๐๐๐ฆโ
1 + ๐บ
4๐
๐ต โฅ๐๐
๐ต๐
RF Wien filter:
๐๐๐ฆโ
1 + ๐บ
4๐๐พ
๐ต โฅ๐๐
๐ต๐
RF dipole:
๐๐๐ฆโ
1 + ๐พ๐บ
4๐
๐ต โฅ๐๐
๐ต๐
2 โ ๐๐ฆ ๐๐ ๐น kHz
๐๐ฆ
๐ ๐๐ฆ Hz
M.A. Leonova et al.,
contribution to Spin 2008
From driven vertical oscillation at fixed frequency
From froissart-Stora scans
RF ๐ร๐ Wien filter protoype performs like an RF solenoid
Development of waveguide RF Wien Filter
[email protected] Search for permanent Electric Dipole Moments using storage rings 78
Device will be installed in PAX low-๐ฝ section
Device developed at IKP in cooperation with:
โข RWTH Aachen, Institute of High Frequency Technology:
o Dirk Heberling, Dominik Hรถlscher, and PhD Student Jamal Slim
โข ZEA-1 of Jรผlich:
o Helmut Soltner, Lars Reifferscheidt, Heidi Straatmann
Some features of the new RF Wien filter
[email protected] Search for permanent Electric Dipole Moments using storage rings 79
Waveguide provides ๐ธ ร ๐ต by design.
Ferrit cage
Mechanical
support
RF
feedthrough
Device rotatable
by 900 in situ
BPM
(Rogowski coil)
Copper
electrodes
Vacuum vessel with
small angle rotator
Clamps for the Ferrit cage
Belt drive for 900 rotation
Ferrit cage
Beam pipe (CF 100)
Support structure
for electrodes Inner support
tube
Support for geodetics
Aim is to build the best possible device with respect to
electromagnetic performance, mechanical tolerances, etc.
Internal structure of the device
[email protected] Search for permanent Electric Dipole Moments using storage rings 80
Ceramic
insulators
copper electrodes with
the trapezium shaping
at the edges
Sliding connector
to RF
Mechanical support
for electrodes
Clamps
supporting the
Ferrit cage
Inner support
tube
Design completed, production started, device available in fall 2016.
Electromagnetic field simulations
[email protected] Search for permanent Electric Dipole Moments using storage rings 81
โข Full-wave simulation with CST Microwave Studio
โข Each simulation required ~12 hours of computer time
Excellent cooperation with RWTH and ZEA
Lorentz force compensation
[email protected] Search for permanent Electric Dipole Moments using storage rings 82
Providing minimal integral Lorentz force requires careful shaping of electrodes and
all other components
๐น ๐ฟ = ๐(๐ธ + ๐ฃ ร ๐ต)
Lorentz force integral with ๐ฃ along Wien filter axis
Mechanical design completed. Continued work on RF driving circuit.
Goal is to reach ๐ต๐๐~0.5 Tmm possible.
[email protected] Search for permanent Electric Dipole Moments using storage rings 83
RF ๐ ร ๐ Wien Filter: Resonance conditions
๐๐ ๐น = ๐rev(๐พ๐บ ยฑ ๐พ), ๐พ โ โค
Frequency range RF Wien filter prototype (Gebel/Mey)
๐พ โ4 โ3 โ2 โ1 0 +1 +2
|๐๐ ๐น|/kHz
๐ 1621.2 871.0 120.8 629.4 1379.6
๐ 1545.6 752.6 40.3 833.2 1626.2
๐ ๐rev/kHz ๐บ ๐ฝ ๐พ ๐พ๐บ
๐ 970.0 750.2 โ0.143 0.459 1.126 โ0.161
๐ 521.1 752.6 1.793 0.486 1.144 2.051
New waveguide RF Wien filter will provide resonance conditions
for deuterons and protons for a number harmonics ๐พ.
Concept for first measurements
[email protected] Search for permanent Electric Dipole Moments using storage rings 84
EDM hidden underneath imperfections from magnet misalignments.
M Rosenthal et al, IBIC 2015
๐ =๐๐โ
2๐๐๐
๐ = 5 โ 10โ20 e cm
Simulations with COSY-INF. and RF Wien filter (๐ธ๐ฅ, ๐ต๐ฆ) in EDM buildup mode.
[email protected] Search for permanent Electric Dipole Moments using storage rings 85
Concept for first measurements
โข With an RF Wien filter of ๐ต๐๐ = 0.05 Tmm, ๐๐ ๐ก๐๐ก~2 โ 10โ22 e cm can be
reached in 1000 s. M Rosenthal et al, IBIC 2015
Randomized error standard deviation of 0.1 mm โ RMS displacements ~1mm.
Contribution to buildup from misalignments similar to EDM for ฮท = 10โ4,
๐ = 5 โ 10โ19 e cm.
Results from the December 2015 run at COSY
[email protected] Search for permanent Electric Dipole Moments using storage rings 86
1. Rotate deuteron spins into ring plane and let them freely precess.
2. Lock the solenoid RF phase to the polarization direction of the ensemble
3. Use small RF solenoid amplitude to mimic polarization buildup
Phase-locking now works via changing of the COSY RF (first try).
Later, we will phase-lock to RF Wien filter RF.
โข During commissioning, waveguide RF Wien filter will be rotated to observe
RF phase-dependence with small amplitudes
Volker Hejny, Ed Stephenson
Outline
[email protected] Search for permanent Electric Dipole Moments using storage rings 87
โข Introduction
โข Recent Achievements
โข Spin coherence time
โข Spin tune measurement
โข Study of magnetic machine imperfections
โข Technical challenges
โข Toward a first direct ๐, ๐ EDM measurement
โข Conclusion
Step Aim / Scientific goal Device / Tool Storage ring
1 Spin coherence time studies Horizontal RF-B spin flipper COSY
Systematic error studies Vertical RF-B spin flipper COSY
2
COSY upgrade Orbit control, magnets, โฆ COSY
First direct EDM
measurement at ๐๐โ2?๐๐๐ฆ RF ๐ธ ร ๐ต Wien filter
Modified
COSY
3 Built dedicated all-in-one ring
for ๐, ๐, 3He
Common magnetic-
electrostatic deflectors
Dedicated
ring
4 EDM measurement of ๐, ๐, 3He at ๐๐โ๐๐๐๐๐ฆ
Dedicated
ring
[email protected] Search for permanent Electric Dipole Moments using storage rings 88
Timeline: Stepwise approach towards all-in-one machine
Time scale: Steps 1 and 2: < ๐ years
Steps 3 and 4: > ๐ years
JEDI Collaboration
โข JEDI = Jรผlich Electric Dipole Moment Investigations
โข ~100 members (Aachen, Dubna, Ferrara, Indiana, Ithaka,
Jรผlich, Krakow, Michigan, Minsk, Novosibirsk, St
Petersburg, Stockholm, Tbilisi, โฆ
http://collaborations.fz-juelich.de/ikp/jedi/)
โข ~ 10 PhD students
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May the force be
with us!
โข EDMs offer new window to disentangle sources of ๐ถ๐ violation,
and to explain matter-antimatter asymmetry of the universe.
โข First direct EDM measurements (๐, ๐ ) at COSY (10โ2? e โ cm) < 2019
โข Development of a dedicated EDM storage ring (10โ29 e โ cm) โข Conceptual design report 2019
โข Spin tune determination is a new precision tool for accelerator studies
โข Map out magnetic imperfections in a machine
โข Successful phase-locking of spin precession to solenoid RF
โข Development of high-precision spin tracking tools, incl. RF structures.
โข Development of electrostatic deflectors (also ๐ธ๐ ร ๐ต๐ฆ), BPMs etc.
[email protected] Search for permanent Electric Dipole Moments using storage rings 90
Conclusion
Very challenging โฆ, but the physics is fantastic.
Georg Christoph Lichtenberg (1742-1799)
โMan muร etwas Neues machen, um etwas Neues zu sehen.โ
โYou have to make (create) something new,
if you want to see something newโ
[email protected] 91 Search for permanent Electric Dipole Moments using storage rings
Publications
Experiment:
1. A. Lehrach, B. Lorentz, W. Morse, N.N. Nikolaev, F. Rathmann, Precursor Experiments to
Search for Permanent Electric Dipole Moments (EDMs) of Protons and Deuterons at
COSY, e-Print: arXiv:1201.5773 (2012).
2. N.P.M. Brantjes et al., Correcting systematic errors in high-sensitivity deuteron polarization
measurements, Nucl. Instrum. Meth. A664, 49 (2012), DOI: 10.1016/j.nima.2011.09.055
3. P. Benati et al., Synchrotron oscillation effects on an rf-solenoid spin resonance, Phys. Rev.
ST Accel. Beams 15 (2012) 124202, DOI: 10.1103/PhysRevSTAB.15.124202.
4. Frank Rathmann, Artem Saleev, N.N. Nikolaev [JEDI and srEDM Collaborations], The search for
electric dipole moments of light ions in storage rings, J. Phys. Conf. Ser. 447 (2013) 012011,
DOI: 10.1088/1742-6596/447/1/012011.
5. Z. Bagdasarian et al., Measuring the Polarization of a Rapidly Precessing Deuteron Beam,
Phys. Rev. ST Accel. Beams 17 (2014) 052803, DOI: 10.1103/PhysRevSTAB.17.052803.
6. F. Rathmann et al. [JEDI and srEDM Collaborations], Search for electric dipole moments of
light ions in storage rings, Phys. Part. Nucl. 45 (2014) 229,
DOI: 10.1134/S1063779614010869.
7. D. Eversmann et al. [JEDI Collaboration], New method for a continuous determination of the
spin tune in storage rings and implications for precision experiments, Phys. Rev. Lett. 115,
094801 (2015), DOI: 10.1103/PhysRevLett.115.094801
[email protected] Search for permanent Electric Dipole Moments using storage rings 92
Theory:
J. Bsaisou, J. de Vries, C. Hanhart, S. Liebig, Ulf-G. Meiรner, D. Minossi, A. Nogga, A. Wirzba,
Nuclear Electric Dipole Moments in Chiral Effective Field Theory, Journal of High Energy
Physics 3, 104 (2015), DOI:10.1007/JHEP03(2015)104