The New Neutron Electric Dipole Moment Experiment at PSI
Martin Fertl on behalf of the nEDM collaboration nedm.web.psi.ch
and on behalf of the UCN Project team Martin Fertl BNL Particle Physics Seminar, 10/28/2010 2 The neutron EDM collaboration
M. Burghoff, S. Knappe-Grüneberg, A. Schnabel, L. Trahms Physikalisch Technische Bundesanstalt, Berlin
G. Ban, Th. Lefort, Y. Lemiere, E. Pierre, Laboratoire de Physique Corpusculaire, Caen G. Quéméner
K. Bodek, St. Kistryn, J. Zejma Institute of Physics, Jagiellonian University, Cracow
A. Kozela Henryk Niedwodniczanski Inst. Of Nucl. Physics, Cracow
N. Khomutov Joint Institute of Nuclear Reasearch, Dubna
P. Knowles, A.S. Pazgalev, A. Weis Département de physique, Université de Fribourg, Fribourg
P. Fierlinger, B. Franke1, M. Horras1, F. Kuchler, G. Petzoldt Excellence Cluster Universe, Garching
D. Rebreyend , G. Pignol Laboratoire de Physique Subatomique et de Cosmologie, Grenoble
G. Bison Biomagnetisches Zentrum, Jena
S. Roccia, N. Severijns Katholieke Universiteit, Leuven
G. Hampel, J.V. Kratz, T. Lauer, C. Plonka-Spehr, Inst. für Kernchemie, Johannes-Gutenberg-Universität, Mainz N. Wiehl, J. Zenner1
W. Heil, A. Kraft, Yu. Sobolev2 Inst. für Physik, Johannes-Gutenberg-Universität, Mainz
I. Altarev, E. Gutsmiedl, S. Paul, R. Stoepler Technische Universität, München
Z. Chowdhuri, M. Daum, M. Fertl, R. Henneck, J. Krempel, B. Lauss, Paul Scherrer Institut, Villigen A. Mtchedlishvili, P. Schmidt-Wellenburg, G. Zsigmond
K. Kirch1, F. Piegsa Eidgenössische Technische Hochschule, Zürich also at: 1Paul Scherrer Institut, 2PNPI Gatchina PhD students www.psi.ch
Martin Fertl BNL Particle Physics Seminar, 10/28/2010 4 Paul Scherrer Institut
• Nuclear and renewable energy Proton cycolotron: • Nuclear safety 600 MeV, 2.2 mA, 1.3 MW • Structural biology, chemistry muons, pions and neutrons for fundamental and applied research
New project: SwissFEL New UCN source
Proton therapy
Swiss Light Source (SLS) synchrotron radiation
Martin Fertl BNL Particle Physics Seminar, 10/28/2010 5 What caused the Baryon asymmetry ?
Andrei Sakharov 1967: B-violation C & CP-violation thermal non-equilibrium [JETP Lett. 5 (1967) 24]
Martin Fertl BNL Particle Physics Seminar, 10/28/2010 6 EDMs and symmetries
σ σ dH E μ B σ σ Thus a nonzero electric dipole moment violates σ σ P, T symmetry and, assuming dPH )E( μ HB CPT conservation, σ alsoσ CP.
(σ) (σ) dTH E μ HB σ σ
Purcell and Ramsey, Phys. Rev. 78, 807 (1950) Landau, Nucl. Phys. 3, 127 (1958) Ramsey, Phys. Rev. 109, 225 (1958)
Martin Fertl BNL Particle Physics Seminar, 10/28/2010 7 Origin of EDMs
need CP-odd phases in fundamental theory d these values should be deduced neutron & proton EDMs
experimentally accessible EDMs of paramagnetic atoms & molecules EDMs of diamagnetic atoms Tl,Cs..,YbF, Hg, Xe, Ra, Rn .. PbO,ThO,HfF +,WC..
Adapted from: A. Ritz, NIMA 611 (2009) 117-123 Martin Fertl BNL Particle Physics Seminar, 10/28/2010 8 The strong CP problem QCD
Why is θQCD so small?
Martin Fertl BNL Particle Physics Seminar, 10/28/2010 9 The SUSY CP problem SUSY
Pospelov, Ritz, Ann. Phys. 318(2005)119 for
MSUSY = 500GeV, tan b = 3
Why is ΦSUSY so small?
Martin Fertl BNL Particle Physics Seminar, 10/28/2010 10 History of nEDM searches
10-19
-20 cm] 10 ORNL, Harvard e current best nEDM limit: 10-21 MIT, BNL -26 LNPI dn < 2.9·10 e cm (90% C.L.) -22 10 Sussex, RAL, ILL C.A.Baker et al., PRL 97, 131801 (2006) 10-23 10-24
-25 Sensitivity goals at PSI 10 Intermediate: -26 ▼ 10 -27 dn < 5 x 10 e cm (95% C.L.) 10-27 Supersymmetry predictions Final: 10-28 -28 dn < 5 x 10 e cm (95% C.L.) 10-31 StandardmodelStandardmodel calculationsincluding CKM -32
Neutron EDM Upper Limit [ EDMNeutron Limit Upper 10 1950 1960 1970 1980 1990 2000 2010 2020 Year of Publication
Martin Fertl BNL Particle Physics Seminar, 10/28/2010 11 Ultracold neutrons ultracold neutrons (UCN) are storable neutrons: Ekin < 330 neV, v < 8 m/s,
λ≈500 Å, T ≈ 3 mK
Simulation of a neutron bottle with confining forces: • Gravity: potential energy 100 neV/m • Material optical potential: < 330 neV E. Fermi, 1946 , Ya. B. Zeldovich Sov. Phys. JETP 9, 1389 (1959)
vn
2 VF=mv C /2
1.5 T • Magnetic field gradient: potential energy ± 60 neV/T
Martin Fertl BNL Particle Physics Seminar, 10/28/2010 12 From cold to ultracold cold neutron UCN
phonon
converter sketch adapted from Chen-Yu Liu, University of Indiana converter types:
• sD2 (PSI, LANL, NCSU, FRM2,…) • sfHe (CryoEDM, SNS, ILL, PNPI,…)
Martin Fertl BNL Particle Physics Seminar, 10/28/2010 13 The PSI UCN source
towards muon and pion beams
Beam dump
Proton cyclotron: 600 MeV, 2.2 mA, 1.3 MW
• UCN Source commissioning started fall 2009 • Expect 1000 UCN/cm3 in typical experiments
(compare to currently 30 UCN/cm3 at ILL)
• nEDM setting up since middle of 2009 nEDM
Martin Fertl BNL Particle Physics Seminar, 10/28/2010 14 2 m3 volume storage trap
-3 UCN guide exp≈ 1000 cm
vacuum compare with typical 30 cm-3 at ILL PF2
The PSI UCN source
30 liters solid D2
p-beam 1.3 MW
3.6 m3 D O 2 • high power (1.3 MW)
• low duty cycle (1%) Martin Fertl BNL Particle Physics Seminar, 10/28/2010• multi-user capability 15
The PSI UCN Source delivery of tank: June December Sept. 04, 2008 2009 2009
spallation target bottle
Martin Fertl BNL Particle Physics Seminar, 10/28/2010 16 The PSI UCN Source
b) 1200 DecDec.18 18, 2009: first beam on target 15:38 #32 - 2mA 1000
500 mm (20”) 800 #29 - 1mA
600
Counts
200 mm #1 kick 14:00 (7.9”) 0.5 400mm AlMg3 0.02” 200
cooling channels made by 40 60wire erosion 80 100 120 140 2 × 1.5 mm AlMg4.5Mn 0.06” Time (min)
Martin Fertl BNL Particle Physics Seminar, 10/28/2010 17 The PSI UCN Source
Martin Fertl BNL Particle Physics Seminar, 10/28/2010 18 The PSI UCN source
20.09.2010
1m 3.3ft
inserting the last UCN guide
UCN storage volume
Martin Fertl BNL Particle Physics Seminar, 10/28/2010 19 Ramsey technique for nEDM
compare neutron clock with stable external reference
working points
Martin Fertl BNL Particle Physics Seminar, 10/28/2010 20 Measurement principle
try to detect a change of the Larmor precession frequency Δ for parallel and anti-parallel B (~1 T) and E fields (~10 kV/cm)
statistical sensitivity only limited by the uncertainty principle:
α Visibility of resonance E Electric field
T Time of free precession
N Number of neutrons
Martin Fertl BNL Particle Physics Seminar, 10/28/2010 21 nEDMflying nEDMapparatusexperiment
field compensation coils
ILL, Grenoble PSI, Villigen
Martin Fertl BNL Particle Physics Seminar, 10/28/2010 22 nEDM apparatus
UCN
Martin Fertl BNL Particle Physics Seminar, 10/28/2010 23 magnetic field requirements I
only if
statistical sensitivity goal: α Visibility of resonance (0.75) E Electric field strength (12 kV/cm)
T Time of free precession (150 s)
N Number of neutrons (350000)
B field requirement: σ(B) 100 fT per one Ramsey cycle (~ 500s)
Martin Fertl BNL Particle Physics Seminar, 10/28/2010 24 magnetometers and SFC
two magnetometer systems:
• 199Hg comagnetometer
• array of laser-driven optically pumped Cs-magnetometers:
4 HV - compatible sensors
8 sensors on ground potential
6 current coils for active sourrounding field compensation (SFC)
Martin Fertl BNL Particle Physics Seminar, 10/28/2010 25 199Hg comagnetometer
• polarized 199Hg atoms sample magnetic field inside the UCN precession chamber at the same time as the UCN (cohabiting)
• optical readout of free spin precession with light from 204Hg lamp • performance: σ(B) ~ 40 fT per 100 s run
29.998
30 pT uncorrected frequency
29.997 corrected Hg comagnetometer correct the UCN precession neutron frequency [Hz] frequency with Hg 29.996 precession frequency
29.995 0 1020304050 t [h] Martin Fertl BNL Particle Physics Seminar, 10/28/2010 26 SFC performance
6 rectangular coils to actively stabilize the surrounding magnetic field
measured with Cs magnetometer array
SFC off
SFC on work in progress
Martin Fertl BNL Particle Physics Seminar, 10/28/2010 27 systematic error contributions
Martin Fertl BNL Particle Physics Seminar, 10/28/2010 28 Cs magnetometer array
4 HV and vacuum compatible HV protection cover Cs magnetometer
Plexiglas optical fiber gallows
UCN and Hg precession volume
survey magnetic fields related to theUCN doors/shutters (“door cavity dipole” ) measure the “uncompensated B drift” (HV reversal related) optical fibers, vacuum magnetic field gradients8 non-HV (geometric vacuum phase compatible effect) Cs magnetometer
Martin Fertl BNL Particle Physics Seminar, 10/28/2010 29 magnetic field requirements II
spatial magnetic field gradients → UCN depolarization (center of mass effect) geometric phase effect
33 individual trim coils outside the vacuum tank to shape the magnetic field
Martin Fertl BNL Particle Physics Seminar, 10/28/2010 30 magnetic field mapping
to address “other dipole fields” and “quadrupole differences”
Martin Fertl BNL Particle Physics Seminar, 10/28/2010 31 magnetic field mapping
Martin Fertl BNL Particle Physics Seminar, 10/28/2010 32 magnetic field mapping map magnetic field in UCN precession chamber with all subsystems installed
+90º HV feed through 0º
Martin Fertl BNL Particle Physics Seminar, 10/28/2010 33 Magnetic screening large pieces are magnetically screened with SQUID array at PTB Berlin BMSR2 15 m
6 m
2.9 m
Martin Fertl BNL Particle Physics Seminar, 10/28/2010 34 Magnetic screening
bottom electrode before degaussing bottom electrode after degaussing 200 pTpp 20 pTpp
isolines 2 pTpp
Martin Fertl BNL Particle Physics Seminar, 10/28/2010 35 Magnetic screening gradiometer setup to magnetically screen small parts before implementation
2 washers from same batch
0.02 nT 1500 nT
holding field in nEDM: 1000 nT
Martin Fertl BNL Particle Physics Seminar, 10/28/2010 36 Further developments
several further improvements have been developed in the collaboration and will be used in the new nEDM measurement:
• new high count rate UCN detectors (~105 cts/s each, 9 detectors) • new spin analyzing foil (single crystal iron foil) • thermal stabilization of Mu-metal shield • new degaussing system for the Mu-metal shield • new bipolar HV power supply • replace massive metal pieces with metal coated plastics
Martin Fertl BNL Particle Physics Seminar, 10/28/2010 37 Summary and outlook
• nEDM experiment successfully transferred to PSI
• PSI UCN source at the end of commissioning → cool down in November 2010
• Design of n2EDM experiment has started to improve sensitivity to 5 x 10-28 ecm (2012+).
Thank you!
Martin Fertl BNL Particle Physics Seminar, 10/28/2010 38