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Fundamental Physics at
MESANiklaus Berger
Institut für Kernphysik, Johannes-Gutenberg Universität Mainz
PRISMA Retreat September 2015
Particle Physics: What are the fundamental constituents of matter
and how do they interact?
Niklaus Berger – PRISMA September 2015 – Slide 3
The Standard Model of Elementary Particles
Niklaus Berger – PRISMA September 2015 – Slide 4
Hugely successful Magnetic moment of the electron:
• Theory: ge = -2.002 319 304 363 56 (154)
(Aoyama et al., PRL 109, 111807 (2012))
• Experiment: ge = - 2.002 319 304 361 53 (53)
(Hanneke et al. PRL 100, 120801 (2008))
Open Questions?
Niklaus Berger – PRISMA September 2015 – Slide 6
In the Standard Model of particle physics
Dark Matter
NASA: HST and Chandra
Niklaus Berger – PRISMA September 2015 – Slide 7
In the Standard Model of particle physics
Dark Matter
NASA: HST and Chandra
Niklaus Berger – PRISMA September 2015 – Slide 8
Matter-Antimatter Asymmetry
10’000’000’000
Antimatter
10’000’000’001
Matter
Matter-Antimatter Asymmetry
1
UsRadiation
Niklaus Berger – PRISMA September 2015 – Slide 10
In the Standard Model of particle physics
Gravity
Niklaus Berger – PRISMA September 2015 – Slide 11
The Structure of the Standard Model
Niklaus Berger – PRISMA September 2015 – Slide 12
The Structure of the Standard Model
τ
1 eV 1 KeV 1 MeV 1 GeV 1 TeV 103 TeV 106 TeV 109 TeV 1012 TeV 1015 TeV 1018 TeV1 meV1 μeV
Neutrinos eu
dsμ
cb W
ZH
t
Planck-Scale(Gravity)
Niklaus Berger – PRISMA September 2015 – Slide 13
The Structure of the Standard Model
τ
1 eV 1 KeV 1 MeV 1 GeV 1 TeV 103 TeV 106 TeV 109 TeV 1012 TeV 1015 TeV 1018 TeV1 meV1 μeV
Neutrinos eu
dsμ
cb W
ZH
t
Planck-Scale(Gravity)
Niklaus Berger – PRISMA September 2015 – Slide 14
The Structure of the Standard Model
τ
1 eV 1 KeV 1 MeV 1 GeV 1 TeV 103 TeV 106 TeV 109 TeV 1012 TeV 1015 TeV 1018 TeV1 meV1 μeV
Neutrinos eu
dsμ
cb W
ZH
t
Planck-Scale(Gravity)
h ht
t
Niklaus Berger – PRISMA September 2015 – Slide 15
The Structure of the Standard Model
τ
1 eV 1 KeV 1 MeV 1 GeV 1 TeV 103 TeV 106 TeV 109 TeV 1012 TeV 1015 TeV 1018 TeV1 meV1 μeV
Neutrinos eu
dsμ
cb W
ZH
t
Planck-Scale(Gravity)
LHC ? ?
Direct production
Indirect effects in quantum loops
Indirect effects in quantum loops
Large discovery reach if:
• Many incoming particles
• Long lifetime
• Little/very well understood Standard Model background
Niklaus Berger – PRISMA September 2015 – Slide 19
• The Idea: Searching for new physics with the weak mixing angle
• The Machine: Mainz Energy-Recovery Superconducting Accelerator
• Experiment I: Weak mixing angle with P2
• Experiment II: Dark photons, proton radius etc. with MAGIX
• More experiments: Dark matter, electron electric dipole moment etc.
Overview
Niklaus Berger – PRISMA September 2015 – Slide 20
The weak mixing angle
(also: Weinberg-angle)
Niklaus Berger – PRISMA September 2015 – Slide 21
• One of the fundamental parameters of the standard model
• Electroweak symmetry breaking creates photon and Z0
• Angle shows up both in masses and couplings (charges)
The weak mixing angle
Niklaus Berger – PRISMA September 2015 – Slide 22
• The last slide is true at tree level
• But there are quantum corrections...
Two options:
• Use the masses for the definition: (at all orders of perturbation theory) “On-shell scheme”
• Or use the couplings: (which change with energy, and so does the angle) “MS-scheme”
• Use second option from here on
Which weak mixing angle?
Niklaus Berger – PRISMA September 2015 – Slide 23
Weak mixing angle and charges
Proton electric charge +e
Proton weak charge 1 - 4 sin2θW
Niklaus Berger – PRISMA September 2015 – Slide 24
Scale dependence (running) of sin2θW
Niklaus Berger – PRISMA September 2015 – Slide 25
Scale dependence (running) of sin2θW
Q [ G e V ] 1000 0 100 0 10 0 1 0 1 0 .1 0 . 0 1 0 . 00 1 0 . 000 1
0 . 24 5
0 . 2 4
0 . 23 5
0 . 2 3
0 . 22 5 sin 2 θW ( Q )
Q W ( APV )
Q W ( e )
Q W ( p )
LEP1
SLD
Nu T eV
eDIS T e v atron A TLAS
CMS hs
Niklaus Berger – PRISMA September 2015 – Slide 26
Scale dependence (running) of sin2θW
Q [GeV]1000010001001010.10.010.0010.0001
0.245
0.24
0.235
0.23
0.225sin2 θW (Q )
QW (APV )
QW (e)
QW (p)
LEP1
SLD
P2@MESA
Moller
Qweak
SOLID
NuTeV
eDIS TevatronATLAS
CMS
hs
Niklaus Berger – PRISMA September 2015 – Slide 27
New Physics in the running
Q [GeV]1000010001001010.10.010.0010.0001
0.245
0.24
0.235
0.23
0.225sin2 θW (Q )
QW (APV )
QW (e)
QW (p)
LEP1
SLD
P2@MESA
Moller
Qweak
SOLID
NuTeV
eDIS TevatronATLAS
CMS
hs
Niklaus Berger – PRISMA September 2015 – Slide 28
Marciano et al.
Dark Z in mixingmdark Z 100 MeVmdark Z 200 MeV
APV Cs
Qweak firstE158
SLAC
LEP
DIS
MollerMESA
Qweak
''Anticipated sensitivities''
3 2 1 0 1 2 3
0.230
0.232
0.234
0.236
0.238
0.240
0.242
Log10 Q GeV
sin2 Θ
WQ
2
Niklaus Berger – PRISMA September 2015 – Slide 29
Contact interactions up to
49 TeV(comparable to LHC at 300 fb-1)
Contact Interactions
Niklaus Berger – PRISMA September 2015 – Slide 30
How to measure the weak charge?
Niklaus Berger – PRISMA September 2015 – Slide 31
Weak mixing angle and charges
Proton electric charge +e
Proton weak charge 1 - 4 sin2θW
Niklaus Berger – PRISMA September 2015 – Slide 32
Weak mixing angle and charges
Proton electric charge +e
Proton weak charge 1 - 4 sin2θW
Violates parity!
Niklaus Berger – PRISMA September 2015 – Slide 33
Parity violating electron scattering
Proton Target
Electron beam
Detector
Niklaus Berger – PRISMA September 2015 – Slide 34
Parity violating electron scattering
Proton Target
Electron beam
Detector
Niklaus Berger – PRISMA September 2015 – Slide 35
Parity violating electron scattering
Proton Target
Electron beam
Detector
Niklaus Berger – PRISMA September 2015 – Slide 36
Parity violating electron scattering
Proton Target
Electron beam
Detector
Momentum transfer sets scale
Weak charge - what we want
Proton structure - small nuisance if Q2 small
Niklaus Berger – PRISMA September 2015 – Slide 37
Parity violating electron scattering
Proton Target
Electron beam
Detector
Momentum transfer sets scale
Weak charge - what we want
Proton structure - small nuisance if Q2 small
Niklaus Berger – PRISMA September 2015 – Slide 38
• sin2θW ≈ 0.25: Weak charge is tiny
• At low Q2: Asymmetry is tiny (40 parts per billion): need very large statistics
• We are subtracting two huge numbers from each other (not really - switching helicity with a few KHz)
Why is this difficult?
Niklaus Berger – PRISMA September 2015 – Slide 39
-810 -710 -610 -510 -410 -310-1010
-910
-810
-710
-610
-510
-410
PVeS Experiment Summary
100%
10%
1%
G0
G0
E122
Mainz-Be
MIT-12C
SAMPLE H-I
A4A4
A4
H-IIH-He
E158
H-III
PVDIS-6
PREX-IPREX-II
Qweak
SOLID
Moller
MESA-P2
MESA-12C
PioneeringStrange Form Factor (1998-2009)S.M. Study (2003-2005)JLab 2010-2012Future
PVA
)PV
(A
Niklaus Berger – PRISMA September 2015 – Slide 40
• Want to measure sin2θW to 0.13%
• Need QW at 1.5%
• Essentially means 1.5% on APV
• APV is 40 parts per billion
• δ(APV) is 0.6 parts per billion
• N a few 1018
• Measure 10’000 hours (absolute maximum anyone thinks shifts are organisable)
• Need close to 1011 electrons/s - 100 GHz
How much statistics do we need?
Niklaus Berger – PRISMA September 2015 – Slide 41
Yes!
• 150 μA of electron beam current
• 60 cm long liquid hydrogen target
• Luminosity 2.4 1039 s-1cm-2
• Integrate 8.6 ab-1
Can we get that rate?
Proton Target
Electron beam
Detector
Niklaus Berger – PRISMA September 2015 – Slide 42
10’000 hours is 417 days 24/7 of measurements
Hard to get that amount of time at a shared accelerator facility...
Niklaus Berger – PRISMA September 2015 – Slide 43
If you cannot rent it, build it:
The MESA accelerator
Mainz Energy-recovery Superconducting Accelerator
Niklaus Berger – PRISMA September 2015 – Slide 44
• Beam current 150 μA
• Polarisation > 85%
• High precision polarimetry
• High runtime (more than 4000 h/year)
• Fit into existing halls at MAMI
• Extremely stable
Requirements
cryomodules
external Experiment
“P2”
internal experiment
Niklaus Berger – PRISMA September 2015 – Slide 45
The main worry are beam fluctuations correlated with the helicity: Achieved at MAMI sin2θW uncertainty requirement
• Energy fluctuations: 0.04 eV < 0.1 ppb ok!
• Position fluctuations 3 nm 5 ppb 0.13 nm
• Angle fluctuations 0.5 nrad 3 ppb 0.06 nrad
• Intensity fluctuations 14 ppb 4 ppb 0.36 ppb
Stability Requirements
Niklaus Berger – PRISMA September 2015 – Slide 46
MESA
P2
MAGIX
SRF Cryo Modules
Mainz Energy Recoving Superconducting AcceleratorMESA
New experimental hall (Forschungsbau )
E xisting experimental
halls
MESA
ERL arc
extracted
beam
Niklaus Berger – PRISMA September 2015 – Slide 47
Teichert et al. NIM A 557 (2006) 239
Superconducting Cryomodules
BEAM PIPE VALVE
BEAM PIPE
ALIGNMENTPARTS
COOL DOWN
LHe FEED PIPE
He GAS RETURN
He GAS COLLECTOR
STAINLESS STEELVACUUM VESSEL
SUPPORT SYSTEMLN2-PORT LN2-RESERVOIR
LN2 LEVELMETER
TUNING SYSTEM
SUSPENSION CABLE(SUPPORT SYSTEM)
TITANIUM TANKBATH CRYOSTAT
80K SHIELDING
MAIN COUPLER COLD PART
CENTER POINT FOLDERSHIELDINGS & TANDEMSUPPORT SYSTEM
NIOBIUM CAVITY
TUNING SYSTEMLHe LEVELMETER
ALIGNMENTPARTS
TANK TANDEM
MAG SHIELDING
LOOP
Niklaus Berger – PRISMA September 2015 – Slide 48
Can we go to higher beam currents?
• In principle yes...
• But power is expensive
• Why dump electrons?
Energy recovery
Niklaus Berger – PRISMA September 2015 – Slide 49
• Put energy back into field!
• Can go up to 1 (10) mA beam current
• But not with a thick target
Energy recovery
Niklaus Berger – PRISMA September 2015 – Slide 50
MESA
P2
MAGIX
SRF Cryo Modules
Mainz Energy Recoving Superconducting AcceleratorMESA
New experimental hall (Forschungsbau )
E xisting experimental
halls
MESA
ERL arc
extracted
beam
Niklaus Berger – PRISMA September 2015 – Slide 51
P2:
How to detect 100 GHz of (the right) electrons...
Niklaus Berger – PRISMA September 2015 – Slide 52
Niklaus Berger – PRISMA September 2015 – Slide 53
Choice of scattering angle
Niklaus Berger – PRISMA September 2015 – Slide 54
Solenoid spectrometer
Niklaus Berger – PRISMA September 2015 – Slide 55
Detector
Solenoid spectrometer
Shield
Niklaus Berger – PRISMA September 2015 – Slide 56
Counting detectors
Proton Target
Electron beam
Detector
Niklaus Berger – PRISMA September 2015 – Slide 57
Integrating detectors
Proton Target
Electron beam
Detector
Niklaus Berger – PRISMA September 2015 – Slide 58
Quartz-Bars & Photomultipliers
Detect Cherenkov-light created by electrons Integrate photomultiplier current
Measuring Q2:
Tracking a lot of low momentum particles
Niklaus Berger – PRISMA September 2015 – Slide 60
Tracker requirement
• Low momentum electrons: Thin detectors
• Very high rates: Fast and granular detectors
Solenoid
Beam axis
Tracking detector
Target
Integrating Detectors
Niklaus Berger – PRISMA September 2015 – Slide 61
Fast, thin, cheap pixel sensors
High Voltage Monolithic Active Pixel Sensors
Niklaus Berger – PRISMA September 2015 – Slide 62
High voltage monolithic active pixel sensors - Ivan Perić
• Use a high voltage commercial process (automotive industry)
• Small active region, fast charge collection via drift
• Implement logic directly in N-well in the pixel - smart diode array
• Can be thinned down to < 50 μm
• Logic on chip: Output are zero-suppressed hit addresses and timestamps (I.Perić, P. Fischer et al., NIM A 582 (2007) 876 )
Fast and thin sensors: HV-MAPS
P-substrate
N-well
Particle
E �eld
Niklaus Berger – PRISMA September 2015 – Slide 63
HV-MAPS chips: AMS 180 nm HV-CMOS
• 5 generations of prototypes
• Current generation: MUPIX7 40 x 32 pixels 80 x 103 μm pixel size 9.4 mm2 active area
• MUPIX7 has all features of final sensor
• Left to do: Scale to 2 x 2 cm2
The MUPIX chip prototypesMUPIX2
MUPIX4
MUPIX6
Niklaus Berger – PRISMA September 2015 – Slide 64
Test beam at DESY
Niklaus Berger – PRISMA September 2015 – Slide 65
Position resolution given by pixel size
Position Resolution
Niklaus Berger – PRISMA September 2015 – Slide 66
Hit efficiency above 99% without tuning
Efficiency
Niklaus Berger – PRISMA September 2015 – Slide 67
Hit timestamp resolution better than 17 ns (significant setup contribution in the measurement)
Time resolution
-400 -200 0 400
500
1000
1500
2000
2500
3000
200Difference between trigger and timestamp [ns]
σ = 16.6 ns
Hits
per
10
ns b
in Timestamp frequency 100 MHz
Niklaus Berger – PRISMA September 2015 – Slide 68
Built our own pixel telescope
• Four planes of thin Mupix sensors
• Fast readout into PCIe FPGA cards
• Currently about 1 MHz hits/plane possible
• Tested at DESY, PSI and MAMI
Mupix Telescope
Niklaus Berger – PRISMA September 2015 – Slide 69
IntroductionY
• X
Niklaus Berger – PRISMA September 2015 – Slide 70
IntroductionY
• X
Niklaus Berger – PRISMA September 2015 – Slide 71
IntroductionY
• X
Niklaus Berger – PRISMA September 2015 – Slide 72
• 50 μm silicon
• 25 μm Kapton™ flexprint with aluminium traces
• 25 μm Kapton™ frame as support
• Less than 1‰ of a radiation length per layer
Mechanics
Niklaus Berger – PRISMA September 2015 – Slide 73
Niklaus Berger – PRISMA September 2015 – Slide 74
Y
• X
P2
Niklaus Berger – PRISMA September 2015 – Slide 75
Where are the neutrons in the nucleus?
Neutron Skins
Niklaus Berger – PRISMA September 2015 – Slide 76
Where are the neutrons in the nucleus?
• Gives access to the equation of state of neutron matter
• Tells us how big/small neutron stars are
Neutron Skins
Niklaus Berger – PRISMA September 2015 – Slide 77
• Not charged: Photons not a good probe
• Use parity violating electron scattering: Proton weak charge is almost zero - see mostly neutrons
How to see the neutrons?
Niklaus Berger – PRISMA September 2015 – Slide 78
And now for something different:
MAGIX
Mesa Gas Internal Target Experiment
Niklaus Berger – PRISMA September 2015 – Slide 79
MAGIX Spectrometer
Niklaus Berger – PRISMA September 2015 – Slide 80
Energy recovery: We want the beam back
• Energy loss less than 10-3
• As little scattering as possible No target window
High resolution spectrometer
• No beam interactions in target window
• As little scattering as possible Thin walls, thin detectors
Extremely intense beam: Do not need very high acceptance
Requirements
Niklaus Berger – PRISMA September 2015 – Slide 81
• Inject gas directly into the beam pipe
• Differential pumping to keep beam vacuum
Internal gas target
Niklaus Berger – PRISMA September 2015 – Slide 82
Twin-arm dipole spectrometer
TARDIS
Niklaus Berger – PRISMA September 2015 – Slide 83
• Image momentum to position
• 10-4 momentum resolution for 50 μm position resolution
TARDIS
Target
Target
Detector
Detector
• Image angle to position
Niklaus Berger – PRISMA September 2015 – Slide 84
Gas Electron Multipliers (GEMs)
• Metalized Kapton foil with tiny holes
• Apply electric field
Focal plane detectors
Niklaus Berger – PRISMA September 2015 – Slide 85
Gas Electron Multipliers (GEMs)
• Metalized Kapton foil with tiny holes
• Apply electric field
• Stack GEMs to reduce ion back drift
• PRISMA detector lab
Focal plane detectors
Niklaus Berger – PRISMA September 2015 – Slide 86
The proton, dark photons and more:
Physics at MAGIX
Niklaus Berger – PRISMA September 2015 – Slide 87
How big is a proton? (electromagnetic charge radius)
• Measure in scattering experiments (Mainz!)
Proton Radius Puzzle
0.85 0.9Proton Charge Radius (fm)
µH (A. Antognini et al.)
µH (R. Pohl et al.)
CODATA
JLab (X. Zhan et al.)
MAMI (J. Bernauer et al.)
Niklaus Berger – PRISMA September 2015 – Slide 88
How big is a proton? (electromagnetic charge radius)
• Measure in scattering experiments (Mainz!)
• Measure in spectroscopy (Lamb-shift)
Proton Radius Puzzle
0.85 0.9Proton Charge Radius (fm)
µH (A. Antognini et al.)
µH (R. Pohl et al.)
CODATA
JLab (X. Zhan et al.)
MAMI (J. Bernauer et al.)
Niklaus Berger – PRISMA September 2015 – Slide 89
How big is a proton? (electromagnetic charge radius)
• Measure in scattering experiments (Mainz!)
• Measure in spectroscopy (Lamb-shift)
• Lamb shift is tiny - except in muonic hydrogen
Proton Radius Puzzle
0.85 0.9Proton Charge Radius (fm)
µH (A. Antognini et al.)
µH (R. Pohl et al.)
CODATA
JLab (X. Zhan et al.)
MAMI (J. Bernauer et al.)
Niklaus Berger – PRISMA September 2015 – Slide 90
How big is a proton? (electromagnetic charge radius)
• Measure in scattering experiments (Mainz!)
• Measure in spectroscopy (Lamb-shift)
• Lamb shift is tiny - except in muonic hydrogen
• Big surprise! 4 - 7 σ discrepancy - why?
Proton Radius Puzzle
0.85 0.9Proton Charge Radius (fm)
µH (A. Antognini et al.)
µH (R. Pohl et al.)
CODATA
JLab (X. Zhan et al.)
MAMI (J. Bernauer et al.)
Niklaus Berger – PRISMA September 2015 – Slide 91
Introduction
Niklaus Berger – PRISMA September 2015 – Slide 92
• Scattering experiments happen at finite momentum transfer Q2
• They will see some of the proton substructure
• Charge radius is defined at Q2 = 0
• Need to extrapolate: Potentially large error
• Want to measure at as small Q2 as possible
Scattering, Q2 and substructure
— Belushkin (Disp. Analysis 2007)
MESA projected error
Jones (JLab 2000)
Gayou (JLab 2001)
Dietrich (MAMI 2001)
Pospischil (MAMI 2001)
Punjabi (JLab 2005)
Jones (JLab 2006)
MacLachlan (JLab 2006)
Crawford (Bates 2007)
Zhan (JLab 2011)
– Bernauer (MAMI 2010)
Q2 / (GeV2/c2)
µpG
p E/G
p M
1010.10.01
1.1
1
0.9
0.8
0.7
0.6
Niklaus Berger – PRISMA September 2015 – Slide 93
There is dark matter out there...
• There could be additional U(1) gauge symmetries with an exchange particle (dark photon, mass mγ’)
• It could mix with the photon via heavy fermions (mixing parameter ε)
• It would then show up as a bump in the e+e- spectrum
Dark photons
Niklaus Berger – PRISMA September 2015 – Slide 94
• Measurement via missing mass method
• Requires detection of low energy proton; challenging
Invisible dark photons
Niklaus Berger – PRISMA September 2015 – Slide 95
Dark photons
]2 [GeV/c'γm-210 -110 1 10
ε
-410
-310
-210
e(g-2)
KLOE 2013
KLO
E 20
14
WASA
HADESPHENIX
σ 2±µ
(g-2)
favored
E774
E141A
PEX
A1
NA48/2
BABAR2009
BABAR2014
BESIIIMESA
Niklaus Berger – PRISMA September 2015 – Slide 96
Dark Matter with the Beam Dump
BDX
Niklaus Berger – PRISMA September 2015 – Slide 97
Search for dark matter
P2
MAGIX
SRF Cryo Modules
Mainz Energy Recoving Superconducting AcceleratorMESA
New experimental hall (Forschungsbau )
E xisting experimental
halls
MESA
ERL arc
extracted
beam
MESA: More than 1022 electrons hit beam dump per year
• Some of them could produce dark matter particles
• “Dark matter beam”
• Detect with DM detector (xenon?) behind beam dump
Niklaus Berger – PRISMA September 2015 – Slide 98
Beam dump dark matter
Niklaus Berger – PRISMA September 2015 – Slide 99
And one more:
Electric dipole moment of electrons
Niklaus Berger – PRISMA September 2015 – Slide 100
• An EDM of a fundamental particle violates CP and T
• Essentially 0 in the SM (tiny contribution from CKM)
• Potentially large in BSM models
• Some more CP violation needed
Electric Dipole Moments
Niklaus Berger – PRISMA September 2015 – Slide 101
Necessary conditions to create baryon asymmetry:
• Baryon number violation
• C and CP violation
• Out of thermal equilibrium
Sakharov Criteria
Matter-Antimatter Asymmetry
10’000’000’000
Antimatter
10’000’000’001
Matter
Niklaus Berger – PRISMA September 2015 – Slide 102
• Spin precesses in magnetic field due to magnetic dipole moment μ
• Spin precesses in electric field due to electric dipole moment d
• μ is large, d is almost zero
Dipole moments and precession
Niklaus Berger – PRISMA September 2015 – Slide 103
Charged particle EDMs
For neutral particles:
• Put in a “box”
• Apply large E-field
• Watch precession
• E.g.: Neutron EDM
For charged particles:
• E field leads to acceleration
• Put electron into a neutral, polar molecule (ACME, Imperial/Sussex)
• Put electron/proton/deuteron etc. in a storage ring
Niklaus Berger – PRISMA September 2015 – Slide 104
• Electric and magnetic fields perpendicular to momentum
• How to get rid of magnetic part?
Precession in a storage ring
Magnetic dipole Electric dipole
Niklaus Berger – PRISMA September 2015 – Slide 105
• No magnetic field! (about 10 MV/m electric field)
Precession in a storage ring
Magnetic dipole Electric dipole
Niklaus Berger – PRISMA September 2015 – Slide 106
• No magnetic field!
• Magic momentum!
• 0.7 GeV/c for protons
• 14.5 MeV for electrons
Precession in a storage ring
Magnetic dipole Electric dipole
Niklaus Berger – PRISMA September 2015 – Slide 107
• Magic momentum
• Spin rotates with momentum vector
• EDM leads to out of plane precession
• Counter-rotating bunches help to cancel systematics
Build an electric-only storage ring
Niklaus Berger – PRISMA September 2015 – Slide 108
• Need very low magnetic field
• Good control of electric field
• Very hard to compete with molecules for limits ...
• ... but only option for a precise measurement ...
• ... and a pathfinder for the proton EDM ( Jülich, Korea...)
Systematics
ACME collaboration, Science 343, 269 (2104)
Niklaus Berger – PRISMA September 2015 – Slide 109
Exciting physics program at MESA:
• Weak mixing angle measurement with P2
• Also gives access to neutron skins
• Proton radius, dark photon and much more with MAGIX
• Second generation of experiments: Beam dump dark matter and electron EDM
• Start 2019/2020
Summary
Niklaus Berger – PRISMA September 2015 – Slide 111
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