Paul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course / 25th-Feb-2005 / T. Prokscha PAUL SCHERRER INSTITUT Fast and Slow Muons at PSI Thomas Prokscha Laboratory for Muon Spin Spectroscopy Paul Scherrer Insitut CH-5232 Villigen PSI Switzerland Isis Muon Training Course, 21 th – 25 th February 2005
45
Embed
Fast and Slow Muons at PSIPaul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course/ 25th-Feb-2005/ T. Prokscha PAUL SCHERRER INSTITUT Fast and Slow Muons at PSI Thomas
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Paul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course / 25th-Feb-2005 / T. Prokscha
PAUL SCHERRER INSTITUT
Fast and Slow Muons at PSI
Thomas Prokscha
Laboratory for Muon Spin SpectroscopyPaul Scherrer InsitutCH-5232 Villigen PSI
Switzerland
Isis Muon Training Course, 21th – 25th February 2005
Paul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course / 25th-Feb-2005 / T. Prokscha
PAUL SCHERRER INSTITUT
RAL/ISIS
PSI
Paul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course / 25th-Feb-2005 / T. Prokscha
PAUL SCHERRER INSTITUT
PSI
Paul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course / 25th-Feb-2005 / T. Prokscha
PAUL SCHERRER INSTITUT
γ SLS
Aareµ SµSn SINQ
Paul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course / 25th-Feb-2005 / T. Prokscha
PAUL SCHERRER INSTITUT
SµS and SINQ
50 MHz proton cyclotron, 2mA,600 MeV
ð quasi-continuous muon andneutron beams
most powerful proton cyloctronworldwidemost intense muon beams
unique low-energy (0.5-30keV)muon beam
Paul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course / 25th-Feb-2005 / T. Prokscha
PAUL SCHERRER INSTITUT
At PSI:∼1016 protons / sec @ 600 MeV (ð 1 MW power on 5x5mm2,40kW/mm2, Fe melts in 0.1ms,electric power demand of 3000 appartments)
∼ 107- 108 µ+/sec, 100 % pol., ∼ 4 MeV
Paul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course / 25th-Feb-2005 / T. Prokscha
PAUL SCHERRER INSTITUT50 MHz beam
Paul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course / 25th-Feb-2005 / T. Prokscha
PAUL SCHERRER INSTITUTContinuous muon beam experiment
Myon-Counter Positron-
Counter
e+sµ pµ
µ+
P(t)P(t=0)
SamplePositron-Counter
ω = γ Β γµ µ µ µ( = 135.5 MHz/T)·
Bext
Paul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course / 25th-Feb-2005 / T. Prokscha
PAUL SCHERRER INSTITUT
Ø time resolution = 1 ns
Ø fast relaxation observable( > 10 µs-1)
Ø no segmentation/positioninformation for e+ necessary
Ø start counter needed
Ø random background (can bereduced by MORE)
Ø limited time window
Ø separator required for surface muons
continuous ïð pulsed
A(σt) = A0 x exp(-ω2σt2/2)
Paul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course / 25th-Feb-2005 / T. Prokscha
PAUL SCHERRER INSTITUT
decay channel, µ+ and µ-E = 15 – 60 MeV
GPD
surface muon beam, µ+E = 0.1 – 4.2 MeV
DOLLY
reconstruction 2004
ALC, LEM, until 2003
LEM 2005
low-energy µ+ (LEM)0.5 – 30 keV
Muon beams at PSI
Paul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course / 25th-Feb-2005 / T. Prokscha
PAUL SCHERRER INSTITUT
Decay and surface muons
Jess Brewer, UBC & TRIUMF:
Paul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course / 25th-Feb-2005 / T. Prokscha
– From macroscopic measurements:controversy about type of superconductivityà BCS conventional ?à Unconventional (p-or d-wave) ?
ÆBulk µSR studies provide a direct measure of the field penetration depth λ(T) àcritical test for typeof superconductivity à weakly coupled s-wave BCS!
Opposite to the situation observed for NaxCoO2 • yH2O (ISIS+PSI)A. Kanigel et al., PRL 92, 257007 (2004)
Examples of µSR Research at PSI
need to measure up to 2.5T ð νµ = 340 MHz(Hc2 = 5.7T)
Paul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course / 25th-Feb-2005 / T. Prokscha
PAUL SCHERRER INSTITUTExamples of µSR Research at PSI
• Evidence of Two LengthScalesin Mg1-xAlxB2 from µSR
S. Serventi et al., PRL 93, 217003 (2004)
– Effect of the two gaps on the internal fielddistribution in the fluxlattice state
– Determine two coherencelength parameters
Paul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course / 25th-Feb-2005 / T. Prokscha
PAUL SCHERRER INSTITUTExamples of µSR Research at PSI
• Measuring the quadrupolar order parameter by µSR – A. Schenck et al., PRL 93, 257601 (2004)– CeB6 (TN = 2.3K and TQ = 3.2K)– Fermi contact hyperfine contribution to the µ+-Knight shift
Acon ∼ quadrupolar order parameter determined from resonant and nonresonant x-ray scattering.
– RKKY induced conduction electron spin polarization depends on theorientation and expectation value of the ordered 4f quadrupole moments.
had to measure Knight shift up to 2.5T( ð νµ = 340 MHz)to gain new insight
Paul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course / 25th-Feb-2005 / T. Prokscha
PAUL SCHERRER INSTITUT
formation of ≈100% polarised spin label by Mu addition to an unsaturated chemical bond:
3 spin-½ system: µ, p, eFermi contact interaction (electron spin density at muon/proton)+ magnetic dipole interaction muon/proton – electron
avoided crossings of magnetic energy levels at high magnetic fields ( ≈2T)⇒ dips in the field-dependence of the µ spin polarisation: ÷ longitudinal field relaxometry: spin-spin cross relaxation
Avoided Level Crossing (ALC)
RR'
+ MuR
R'
Mu H
H
hfc tensor: fixed orientation with respect to the radical
⇒ study of reorientational dynamics
Longitudinal magnetic field:
| α β β >
| α β α >| α α β >
| α α α >
|∆M| = 2
muon-proton
spin flip-flip
|∆M| = 1
muon spin flip
∆M = 0
muon-proton
spin flip-flop
| e µ p >
avoided level crossings: mixing of eigenstates
⇒ time evolution of the µ+ spin polarization
loss of observed FW-BW asymmetry
M = me + m1 + mp
spin-spin cross relaxation
advantages:
• long Mu precursor lifetime (up to 1 µs) - phase coherence lost in TF after 0.1 ns
• low concentrations of tracer molecules, Mu addition within τµ- TF requires ≥ 100 mM for diffusion controlled Mu addition
Paul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course / 25th-Feb-2005 / T. Prokscha
PAUL SCHERRER INSTITUT
surfactant bilayers separated by water
phase transition Tαβ ≈ 50 °C (DSC)T > Tαβ: Lα - alkyl chains ‚fluid‘T < Tαβ: Lβ - more ordered packing of hydrocarbon
chains
lamellar phase:
NH2C
HC
H2C O C
O
CH2
O C
O
CH2
H3CH3C
H3C
Cl
C16H33
C16H33
DHTAC: cationic dichain surfactant
H2CCH2
OH
cosurfactant: 2-phenylethanol(‘perfume’: essence of roses)
partitioning (local environment) of cosurfactants in lamellar phases
Paul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course / 25th-Feb-2005 / T. Prokscha
PAUL SCHERRER INSTITUT
40 mM 2-phenylethanol in 15% DHTAC dispersion
18000 20000 22000
∆0∆1
25 °C
35 °C
45 °C
55 °C
65 °C
75 °C
magnetic field [G]
Lα
Lβ
∆1 resonances only above Tαβ: residual anisotropy! PEA-Mu axially aligned within bilayer lineshape: dynamical averaging
∆0: discontinuity in Bres(T) at Tαβ: change of local environment!
20 30 40 50 60 70 80
20000
20200
20400
20600
20800
LαL
β
ortho-∆ 0
para-∆ 0
meta-∆ 0
Bre
s [G
]
T [°C]
tracer in water in bilayer(but not static!)
3 isomers:
Paul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course / 25th-Feb-2005 / T. Prokscha
Paul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course / 25th-Feb-2005 / T. Prokscha
PAUL SCHERRER INSTITUTMagnetic field profile in YBa2Cu3O7-δ
700
600
500
400
300
200
1000 10 20 30 40 50 60 70 80 90
Thin Film (Meissner state) Thin Film (mixed state) Single crystal (mixed state, Sonier et al., PRL (1994) 744)72
Temperature [K]
λ ab(T
) [n
m]
T.J. Jackson, T.M. Riseman, E.M. Forgan, H. Glückler,T. Prokscha, E. Morenzoni, M. Pleines,Ch. Niedermayer, G. Schatz, H. Luetkens, and J. Litterst, Phys. Rev. Lett. 84, 4958 (2000).
)T(z
0abeB)z(B λ
−=→
Direct, absolute measurementof magnetic penetration depth
Field profile: B(z,T)
)T(n)e(m
)T(s
*ab
ab 20 2µ
=λ
Vortices near surfaceYBa2Cu3O7-d film in vortex state:
π2/a
Flux line lattice magnetic field distribution across the surface
Ch. Niedermayer, E.M. Forgan, H. Glückler, A. Hofer, E. Morenzoni, M. Pleines, T. Prokscha, T.M. Riseman, M. Birke, T.J. Jackson, J. Litterst, M.W. Long, H. Luetkens, A. Schatz, and G. Schatz, Phys.Rev.Lett. 83, 3932-3935 (1999).
LE-muons in multi-layers
Fit-Function:
Free fit parameters:
Multi-layered samples:
-magnetic/non magnetic
-superconducting/ magnetic
-superconducting/ nonsuperconducting
4nm 20nm 4nm
Fe/Ag/Feimplantation profile (3 keV)
LE-muons in Ag/Fe/Ag
Fit:
Observation of the spatially oscillating spin density in Ag !
H. Luetkens, J. Korecki, E. Morenzoni, T. Prokscha, M. Birke, H. Glückler, R. Khasanov, H.-H. Klauss, T. Slezak, A. Suter, E. M. Forgan, Ch. Niedermayer, and F. J. Litterst,Phys Rev. Lett. 91, 017204 (2003).
B(x) and IEC oscillate
with the same period but
attenuation with distance
from interface different !
Paul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course / 25th-Feb-2005 / T. Prokscha
PAUL SCHERRER INSTITUTSuperconducting and magnetic ordering in
Fe/Pb/FeCompare data above and below Tc
T<TcT>Tc
∑ φ+=∝i
nii
i ix)xksin(
A B(x) )x(M
Oscillating polarisation of conducting/superconductingàelectrons
Pb 215 nm
Fe 2,6 nmMo 6 nm
Fe 2,8 nm
uSpin Density Wave in Pb induced above and belowTc with same wave vectors but phase shifts by 900
below Tc
uTolerance (coexistence) and Interaction betweenthe magnetic and superconducting order in the PbfilmuWeaker attenuation of electron polarization than
expected
A. Drew, S. Lee et al: St. Andrews-PSI-Leeds collaborationSubmitted to PRL
Paul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course / 25th-Feb-2005 / T. Prokscha
PAUL SCHERRER INSTITUT
Muon developments and projects at PSI
Ø reconstructed, dedicated µE4 beamline for LEM, 5000/secLE-µ+ on sample, 2005; upgrade of LEM apparatus
Ø high-field µSR instrument, up to 15 T (νµ = 2 GHz)
Ø detector development, fast timing, position information
Ø change of DAQ system to MIDAS, new data format (Nexus)
Ø new VME based DAQ hardware, new progammable VME CFD
Ø GPD upgrade: new magnet (0-6.5kG), new cryostat (0.3-300K), new detectors
Ø active zero field compensation
Paul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course / 25th-Feb-2005 / T. Prokscha
PAUL SCHERRER INSTITUTµE4/LEM beam area
Paul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course / 25th-Feb-2005 / T. Prokscha
PAUL SCHERRER INSTITUT
new LEM beam and LE-µSR spectrometer
Electrostatic (ExB) separator
new µE4 area
Status of LEM- and µE4-reconstruction,Feb-2005
Paul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course / 25th-Feb-2005 / T. Prokscha
PAUL SCHERRER INSTITUT
µSR worldwide
PSI: continuous, the most intense muon beams, MORE, unique LEM beam
TRIUMF: continuous (Vancouver, Kanada)
ISIS: most intense pulsed muon source (near Oxford, Great Britain)
Paul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course / 25th-Feb-2005 / T. Prokscha
PAUL SCHERRER INSTITUT
LMU – Laboratory for Muon Spin Spectroscopy
People at LMU:
Dierk Herlach (LMU Head)Bulk µSR group:
Alex Amato (Group Head), Huberturs Luetkens, Robert Scheuermann, Alexey Stoykov, Ulrich Zimmermann, Chris BainesPhD students: one open position (TU Braunschweig)
LEM group:
Elvezio Morenzoni (Group Head), Thomas Prokscha, Andreas SuterPhD students: two open positions (Univ. Zürich, TU Braunschweig)PostDocs: Dimitri Eshchenko (Univ. Zürich), Suriyakan Vongtragool (Univ. Leiden)
Technicians:
Xavier Donath (bulk, changing to SLS), Stefan Gloor (bulk+LEM), Hans-Peter Weber (LEM)Software support: Secretary:
Andrea Raselli Renate Bercher
(about 300 users from more than 20 countries per year)