villigen, 22.02.2012 status of the nedm measurement progress 2011 psi proposal r–05–03.1 philipp...

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.


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


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


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


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


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


Mercuy comagnetometer


Hg contaminated

Geometric phase

Hg under pressure

Sudden collapse

1st change of electrodes

2nd change of electrodes

3rd change of electrodes


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


Magnetic field gradients

• Most important source of systematic effects

→ Field mapping

→ Online Cs-OPM measurement

→ Combination of online information and field maps


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


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…


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


Cs-OPM response method


Ultra cold neutrons• Regular pulses (every 480s for 4s)

• 900 000 UCN in direct measurements

• 16 000 UCN counted after 4s storagein precession chamber


UCN Detector• Counts neutrons• Can distinguish gammas• Sends

UCN countsto main DAQ


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)


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


UCN Ramsey cyclesRamsey curve taken with 250 s precession time

N0 = 1205

α0 = -0.46


UCN nEDM run


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)


- movable 5 layer cubic shielding(design discussion with companies ongoing)

- active vibration compensation

Phase III


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

villigen, 22.02.2012 status of the nedm measurement progress 2011 psi proposal r–05–03.1 philipp...

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