villigen, 22.02.2012 status of the nedm measurement progress 2011 psi proposal r–05–03.1 philipp...
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Villigen, 22.02.2012
Status of the nEDM measurement
Progress 2011 PSI Proposal R–05–03.1
Philipp Schmidt-Wellenburgon behalf of the nEDM collaboration
Philipp Schmidt-Wellenburg Villigen, BVR 22.02.2012
T
CP violation and EDM
→ CP so far only in weak decay→ Excellent probe for physics
beyond the Standard Model→ Might explain BAU
matter/anti-matter problem
A nonzero particle EDM violates P, T and, assuming CPT conservation, also CP.
Philipp Schmidt-Wellenburg Villigen, BVR 22.02.2012
The measurement technique
Measure the difference of precession frequencies in parallel/anti-parallel fields:
BBμEEdΔ nn 22
for dn<10-26 ω < 60 nHz
RAL-Sussex-ILL:
dn < 2.9 x 10–26 e cm
C.A.Baker et al., PRL 97 (2006) 131801
Philipp Schmidt-Wellenburg Villigen, BVR 22.02.2012
st 2
nRF
The Ramsey technique
Free precessionat ω L
Apply /2 spinflip pulse...
“Spin up” neutron...
Second /2 spinflip pulse.
B0↑
B0↑ + Brf
B0↑
B0↑ + Brf
tT
st 2
Ramsey resonance curve
Sensitivity:
Visibility of resonanceE Electric field strengthT Time of free precessionN Number of neutrons
NETd
2)(
n
nRF
Philipp Schmidt-Wellenburg Villigen, BVR 22.02.2012
Reminder• Phase I:
• Operate and improve OILL@ILL (all cycles 2008)• Moved OILL March 2009 • Design of n2EDM, related R&D
• Phase II:• Operate OILL@PSI (2009-2013) • Sensitivity goal: 5x10-27ecm • Design of n2EDM, construction and setup • R&D
• Phase III:• Operate n2EDM (2014-2017)• Sensitivity goal: 5x10-28ecm
Philipp Schmidt-Wellenburg Villigen, BVR 22.02.2012
Magnetic fields
Magnetic field control:• Four layer mu-metal shield• 33 trim coils (inside shield)• Six compensation coils
(around apparatus)• Mercury comagnetometer• Cesium magnetometer
array
BBμEEdΔ nn 22
Philipp Schmidt-Wellenburg Villigen, BVR 22.02.2012
Mercury co-magnetometer
¼ wave platelinear polarizer
Hg lamps
PM
polarization cell
HgO source
B0 ≈
1μ
T
• Average magnetic field (volume and cycle)
• σ(B) ~ 20 – 50 fT• Center of mass
different than UCN• Important Systematic effects
due to magnetic field gradients
τ = 140s
Philipp Schmidt-Wellenburg Villigen, BVR 22.02.2012
Mercuy comagnetometer
Philipp Schmidt-Wellenburg Villigen, BVR 22.02.2012
Hg contaminated
Geometric phase
Hg under pressure
Sudden collapse
1st change of electrodes
2nd change of electrodes
3rd change of electrodes
Philipp Schmidt-Wellenburg Villigen, BVR 22.02.2012
Cesium magnetometers
Monitoring of vertical magnetic gradients
• Two cesium magnetometer arrays
• Stabilized laser• PID phase locked DAQ
1 2 3 4
5 … 11 12
±140kV
Philipp Schmidt-Wellenburg Villigen, BVR 22.02.2012
Magnetic field gradients
• Most important source of systematic effects
→ Field mapping
→ Online Cs-OPM measurement
→ Combination of online information and field maps
Philipp Schmidt-Wellenburg Villigen, BVR 22.02.2012
Geometric phase• Gradient applied with
trim coils: 0 – 4nT/cm
• E-field: ±100 kV/12cm
• For each setting:B0 up and B0 down
• ~30 polarity changes
• Gradient:Cs-OPM measurement
• ~20h per point
Philipp Schmidt-Wellenburg Villigen, BVR 22.02.2012
Results geometric phase
• For B0 up:
(-9.69 ± 0.33) * 10-27 e cm@ 10 pT/cm
• For B0 down:
(9.94 ± 0.25) * 10-27 e cm@ 10 pT/cm
• Data are in agreement within 15 % to the calculations of Pendlebury1.15 * 10-26 e cm @ 10 pT/cm
• Discrepancy is still investigated, gradients from fluxgate maps seem to agree better…
Philipp Schmidt-Wellenburg Villigen, BVR 22.02.2012
Cs-OPM response method
• Measure the response of each Cs-OPMfor current changes for all trim coils
→ Response Matrix Amn
→ Invert Matrix
→ Calculate currents for each coil to get desired field value
Philipp Schmidt-Wellenburg Villigen, BVR 22.02.2012
Cs-OPM response method
Philipp Schmidt-Wellenburg Villigen, BVR 22.02.2012
Ultra cold neutrons• Regular pulses (every 480s for 4s)
• 900 000 UCN in direct measurements
• 16 000 UCN counted after 4s storagein precession chamber
Philipp Schmidt-Wellenburg Villigen, BVR 22.02.2012
UCN Detector• Counts neutrons• Can distinguish gammas• Sends
UCN countsto main DAQ
Philipp Schmidt-Wellenburg Villigen, BVR 22.02.2012
UCN Spin performance
• Discrepancy for α0 can be explained with UCN counting method
• Manual adjusted emptying sequence
• No manual tuning of trim coils (only Cs response)
Philipp Schmidt-Wellenburg Villigen, BVR 22.02.2012
UCN emptying curve
• Low α0 for T1 and T2 indication for strong depolarization (SC magnet → ~100%)
τflip = 236 s
τloss =16.5 s
τ↓ = 163 s
τ↑ = 16.9 s
N = 29185
α0 = 0.999
Best fit to
data
Philipp Schmidt-Wellenburg Villigen, BVR 22.02.2012
UCN Ramsey cyclesRamsey curve taken with 250 s precession time
N0 = 1205
α0 = -0.46
Philipp Schmidt-Wellenburg Villigen, BVR 22.02.2012
UCN nEDM run
Philipp Schmidt-Wellenburg Villigen, BVR 22.02.2012
Outlook• Characterize UCN switch properties
(April: storage and transmission measurements at ILL)
• Recover excellent Hg performance(bake out electrodes, insulator ring)
• Upgrade Cs-Array to 8 HV, 10 ground sensors• Characterize important UCN parameters with high
UCN density (α , τ, Δh, T1, T2)
• 150 nights nEDM-Data (July-December, 2012)
Philipp Schmidt-Wellenburg Villigen, BVR 22.02.2012
- movable 5 layer cubic shielding(design discussion with companies ongoing)
- active vibration compensation
Phase III
Philipp Schmidt-Wellenburg Villigen, BVR 22.02.2012
also at: 1Paul Scherrer Institut, 2PNPI Gatchina, 3Eidgenössische Technische Hochschule, 4KEK
The Neutron EDM Collaboration
M. Burghoff, A. Schnabel, J. Vogt
G. Ban, V. Helaine1, Th. Lefort, Y. Lemiere, O. Naviliat-Cuncic, E. Pierre1, G. Quéméner
K. Bodek, St. Kistryn, G. Wyszynski3, J. Zejma
A. Kozela
N. Khomutov
Z. Grujic, M. Kasprzak, P. Knowles, H.C. Koch, A. Weis
G. Pignol, D. Rebreyend S. Afach, G. Bison
J. Becker, N. Severijns, R. Chankova
S. Roccia
C. Plonka-Spehr, J. Zenner1
W. Heil, A. Kraft, T. Lauer , D. Neumann, Yu. Sobolev2
Z. Chowdhuri, M. Daum, M. Fertl3 , B. Franke3, M. Horras3, B. Lauss, J. Krempel , K. Mishima4, A. Mtchedlishvili, P. Schmidt-Wellenburg, G. Zsigmond
K. Kirch1, F. Piegsa, D. Ries
Physikalisch Technische Bundesanstalt, Berlin
Laboratoire de Physique Corpusculaire, Caen
Institute of Physics, Jagiellonian University, Cracow
Henryk Niedwodniczanski Inst. Of Nucl. Physics, Cracow
Joint Institute of Nuclear Reasearch, Dubna
Département de physique, Université de Fribourg, Fribourg
Laboratoire de Physique Subatomique et de Cosmologie, Grenoble
Biomagnetisches Zentrum, Jena
Katholieke Universiteit, Leuven
Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse, Orsay
Inst. für Kernchemie, Johannes-Gutenberg-Universität, Mainz
Inst. für Physik, Johannes-Gutenberg-Universität, Mainz
Paul Scherrer Institut, Villigen
Eidgenössische Technische Hochschule, Zürich