Mitglied der Helmholtz-Gemeinschaft Search for permanent electric dipole moments using Storage Rings...
-
Upload
rosaline-jacobs -
Category
Documents
-
view
238 -
download
0
Transcript of Mitglied der Helmholtz-Gemeinschaft Search for permanent electric dipole moments using Storage Rings...
Mit
glie
d d
er
Helm
holt
z-G
em
ein
sch
aft
Search for permanent electric dipole moments using Storage Rings
June 10, 2015 Frank Rathmann on behalf of JEDI
6th International Symposium on Symmetries in Subatomic Physics, Victoria, BC Canada
Search for permanent Electric Dipole Moments using storage rings 2
Outline
• Introduction• EDM search using storage rings
• Recent progress• Spin coherence time• Spin tune measurement• Towards first direct EDM measurement
• Conclusion
[email protected] 3Search for permanent Electric Dipole Moments using storage rings
Permanent EDMs violate both and symmetry.
Assuming to hold, violated also.
Not Charge symmetric (aligned with spin)
EDMs: Discrete Symmetries
: MDM: EDM
EDM:
: :
Search for permanent Electric Dipole Moments using storage rings 4
EDMs: Naive estimate of the nucleon EDM scale
• & conserving magnetic moment nuclear magneton
• A non-zero EDM requires • violation: the price to pay is , and• violation (from K-decays): the price to pay is
• In summary:
• In SM (without term):
Khriplovich & Lamoreux (1997); Nikolaev (2012)
Region to search for BSM physics using nucleon EDMs:
|𝒅𝑵|≈𝟏𝟎−𝟕×𝟏𝟎−𝟑×𝝁𝑵≈𝟏𝟎−𝟐𝟒𝐞𝐜𝐦
|𝒅𝑵𝐒𝐌|≈𝟏𝟎−𝟕×𝟏𝟎−𝟐𝟒≈𝟏𝟎−𝟑𝟏𝐞𝐜𝐦
Search for permanent Electric Dipole Moments using storage rings 5
Prospects of charged particle EDMs:
• No direct measurements of charged hadron EDMs
• Potentially higher sensitivity than neutrons• protons/deuterons are stable• more stored polarized protons/deuterons• larger electric fields
• Approach complimentary to neutron EDM
• EDM of a single particle not sufficient to identify source • access to
Charged particle EDM experiments potentially provide a higher sensitivity than, e.g., nEDM
?
[email protected] 6Search for permanent Electric Dipole Moments using storage rings
For transverse electric and magnetic fields in a ring, theanomalous spin precession is described by Thomas-BMT equation:
Magic condition: Spin along momentum vector
1. For any sign of , in a combined electric and magnetic machine
, where and
2. For (protons) in an all electric ring
(magic)
Concept for srEDM: Frozen spin Method
Magic rings to measure EDMs of free charge particles
ΩMDM=𝑞𝑚 {𝐺 ∙ ��− 𝛾 𝐺𝛾+1
�� ( �� ∙𝐸 )−[𝐺− 1
𝛾 2−1 ] ��× ��𝑐 }(𝐺=𝑔−22 )
• Place particles in a storage ring• Align spin along momentum („freeze“ horizontal spin precession)• Search for time development of vertical polarization
[email protected] 7Search for permanent Electric Dipole Moments using storage rings
Concept: Rings for EDM searches
New Method to measure EDMs of charged particles:• Magic rings with spin frozen along momentum• Polarization buildup
��𝐺=0
𝑑 ��𝑑𝑡
=��× ��
A magic storage ring for protons (electrostatic), deuterons, …
[email protected] 8Search for permanent Electric Dipole Moments using storage rings
particleproton
Concepts: Magic Storage ring
Possible to measure , , using one machine with m
B
deuteron
280.0
��𝐺=0𝑑 ��𝑑𝑡
=��× ��
Search for permanent Electric Dipole Moments using storage rings 9
Goal: provide to the same level
𝝈𝐬𝐭𝐚𝐭 ≈𝟏
√𝑵 ∙ 𝒇 ∙𝝉 ∙𝑷 ∙ 𝑨𝒚 ∙𝑬⇒𝝈𝐬𝐭𝐚𝐭 (𝟏𝐲𝐞𝐚𝐫 )=𝟏𝟎−𝟐𝟗𝐞 ∙𝐜𝐦
• High precision, primarily electric storage ring• alignment, stability, field homogeneity, and shielding from
perturbing magnetic fields• High beam intensity ()• Stored polarized hadrons ()• Large electric fields ()• Long spin coherence time ()• Efficient polarimetry ()
Concept: Experimental requirements
2 beams simultaneously rotating in an all electric ring (CW, CCW)
[email protected] 10Search for permanent Electric Dipole Moments using storage rings
Concept: Beat the systematics
CW CCW
Polarization
EDM
Sokolov-Ternov
Gravitation
CW & CCW beams cancel many systematic effects
Search for permanent Electric Dipole Moments using storage rings 11
Magnetic fields:• Radial field mimics EDM effect when • With in a field of ,
Concept: Systematics
Solution: • Use two beams simultanously, clockwise (CW) and CCW• vertical separation of beam orbits sensitive to
Search for permanent Electric Dipole Moments using storage rings 12
• Splitting of beam orbits: • denotes the vertical betatron tune• Modulate with • Splitting corresponds to • In one year of measurement: fills of each
per fill
Concept: Systematic Orbit splitting (Dave Kawall)
Required sensitivity , achievable only with state-of-the-art SQUID magnetometers.
Search for permanent Electric Dipole Moments using storage rings 13
Recent Progress: Magnetic shielding
Next generation nEDM experiment under development at TUM (FRM II):• Goal: Improve present nEDM limit by factor .• Experiment shall use multi-layer shield.• Applied magnetic field: .
J. Appl. Phys. 117 (2015)
At mHz frequencies, damping of achieved
A
AS
one particle with magnetic moment
“spin tune”
“spin closed orbit vector”COn
s2AS
ring
makes one turn
stable polarizationS
if ║ COn
[email protected] 14Search for permanent Electric Dipole Moments using storage rings
Insert: Spin closed orbit and spin tune
Spin closed orbit
¿2𝜋𝛾𝐺
The number of spin precessions per turn is called spin tune
Challenge: Spin coherence time (SCT)
[email protected] Search for permanent Electric Dipole Moments using storage rings 15
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 along 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!
COn
In a machine with frozen spins the buildup time
to observe a polarization is limited by .
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
[email protected] 16Search for permanent Electric Dipole Moments using storage rings
… an ideal starting pointfor EDM search
Search for permanent Electric Dipole Moments using storage rings [email protected]
turn spin
free precession
polarimeter
Spin coherence time: Experimental investigation
1. Vertically polarized deuterons stored in COSY at
2. Polarization flipped into horizontal plane with RF solenoid (takes )
3. Beam slowly extracted on Carbon target (ramped bump or beam heating)
4. Horizontal (in-plane) polarization determined from Up-Do detector asymmetry
Need to keep track of event time and revolution time from turn to turn
Search for permanent Electric Dipole Moments using storage rings [email protected]
Polarimeter: Experimental investigation of SCT
Detect deuterons from scattering:
• D
Search for permanent Electric Dipole Moments using storage rings [email protected]
Polarimeter: Determination of SCTObserved experimental decay of asymmetry
𝝉𝐒𝐂𝐓≈𝟐𝟎𝐬
𝝉𝐒𝐂𝐓≈𝟒𝟎𝟎𝐬
Using sextupole magnets in the machine, higher order effects can be efficiently corrected
Search for permanent Electric Dipole Moments using storage rings [email protected]
More progress on : A few days ago
Way beyond anybody’s expecations
Search for permanent Electric Dipole Moments using storage rings 21
Spin tune : How to m?
Solution: Map all events into one spin oscillation period
, a priori not known ()• Detector rate is , one hit in detector per beam revolutions
𝝈𝝂 𝒔≈𝟏𝟎−𝟔
Scan in an interval around and find maximum of asymmetry
Search for permanent Electric Dipole Moments using storage rings [email protected]
Spin tune: D
Spin tune determined to in 2 s time interval, and in a cycle at to
Monitor phase of asymmetry with fixed during 100 s cycle
preliminary
See poster by Dennis Eversmann
[1504.00635, 2015]
Search for permanent Electric Dipole Moments using storage rings 23
Precision tool for accel. physics: Spin tune
• Tool to optimze long term stability of a machine• Develop feedback systems to minimize variations• Phase-locking the spin precession to RF devices possible
Observed machine behavior during consecutive cycles
preliminary
[email protected] Search for permanent Electric Dipole Moments using storage rings 24
First direct dEDM measurement : RF Wien filter
Observable:Accumulation of vertical polarization during spin coherence time
Polarimeter (dp elastic)
stored d
RF E(B)-field In-plane polarization
Use COSY for a first direct and EDM measurement:• Statistical sensitivity for in the range to range• Alignment and field stability of ring magnets• Imperfection of RF- flipper
Use an RF technique for proof-of-principle srEDM exp’t• RF device operates on harmonic of spin precession frequency• EDM signal accumulates a function of time
Magic RF Wien Filter: no Lorentz force to avoid coherent betatron oscillations
[email protected] Search for permanent Electric Dipole Moments using storage rings 25
First direct EDM measurement: Deuterons
Parameters: beam energy assumed EDME-field
𝐭𝐮𝐫𝐧𝐧𝐮𝐦𝐛𝐞𝐫
𝑷 𝒙 𝑷 𝒛 𝑷 𝒚
EDM effect accumulates in [Phys. Rev. ST AB 16, 114001 (2013)]
[email protected] Search for permanent Electric Dipole Moments using storage rings 26
EDM effect accumulates in
𝑃 𝑦
𝐭𝐮𝐫𝐧𝐧𝐮𝐦𝐛𝐞𝐫
𝑷 𝒚
Linear extrapolation of for a time period of yields a measurable
First direct EDM measurement: Deuterons
Parameters: beam energy assumed EDME-field
Search for permanent Electric Dipole Moments using storage rings 27
RF Wien Filter: Prototype
Insert RF-dipole into ceramic chamber
Commissioned prototype just performs like an RF solenoid
Search for permanent Electric Dipole Moments using storage rings 28
RF Wien filter: Strip line design
Strip line design provides
Strip-line RF × Wien filter available early 2016.𝐄 𝐁
∫−𝐿
𝐿
𝐵𝑦𝑑𝑧=0.02371Tmm
𝐹𝐿=12𝐿∫
−𝐿
𝐿
𝐹𝐿𝑑𝑧=1.8 ∙10− 4 eVm
Device will be installed in PAX low- section
BPM(Rogowski coil)
Ferrit cageCopper
electrodes
RF feedthrough
Device rotatable by in situ
[email protected] Search for permanent Electric Dipole Moments using storage rings
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:
• Electric field gradients at plate distance
• Spin coherence time
• Continuous polarimetry
• Beam position monitoring
• Spin tracking tools
Issues must be addressed experimentally at existing facilities
Challenges: Overview
Step Aim / Scientific goal Device / Tool Storage ring
1Spin coherence time studies Horizontal RF- spin flipper COSY
Systematic error studies Vertical RF- spin flipper COSY
2COSY upgrade Orbit control, magnets, … COSY
First direct EDM measurement at
RF- spin flipperModified COSY
3Built dedicated all-in-one ring for , ,
Common magnetic-electrostatic deflectors
Dedicated ring
4EDM measurement of , , at Dedicated
ring
[email protected] Search for permanent Electric Dipole Moments using storage rings 30
Timeline: Stepwise approach towards all-in-one machine
Time scale: Steps 1 and 2: years
Steps 3 and 4: years
Search for permanent Electric Dipole Moments using storage rings 31
JEDI Collaboration
• JEDI = Jülich Electric Dipole Moment Investigations
• members (Aachen, Daejeon, Dubna, Ferrara, Indiana, Ithaka, Jülich, Krakow, Michigan, Minsk, Novosibirsk, St Petersburg, Stockholm, Tbilisi, … http://collaborations.fz-juelich.de/ikp/jedi/)
• PhD students
May the force be with us!
• EDMs offer new window to disentangle sources of violation, and to explain matter-antimatter asymmetry of the universe.
• First direct EDM measurements () at COSY
• Development of a dedicated EDM storage ring• Sensitivity goal: • Conceptual design report
• Spin tune determination emerges as novel precision tool for accelerators• Allows mapping magnetic imperfections in a machine
• Development of high-precision spin tracking tools, incl. RF structures.
• Development of electrostatic deflectors (also ), BPMs etc.
[email protected] Search for permanent Electric Dipole Moments using storage rings 32
Conclusion
srEDM experiments are very challenging …,
but the physics is fantastic
33
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] Search for permanent Electric Dipole Moments using storage rings
Search for permanent Electric Dipole Moments using storage rings 34
PublicationsExperiment:
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, eprint arXiv:1504.00635 (2015)
Theory:
J. Bsaisou, J. de Vries, C. Hanhart, S. Liebig, Ulf-G. Meißner, 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