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
PAUL SCHERRER INSTITUTµSR instruments at PSI
Ø GPS: General Purpose Surface muon instrument; permanent installation;πM3 beam shared with LTF; 4 MeV µ+, Separator/Spin Rotator ( 6 – 60o);0 – 0.6 T, 1.8 – 300 K; Muons on Request ( MORE)
Ø LTF: Low Temperature Facility; permanent installation; πM3 beamshared with GPS; 0 – 3 T, 0.01 K – 4.2 K; MORE
Ø Dolly: GPS „clone“; πE1 or πE3 beam, new Spin Rotator
Ø GPD: General Purpose Decay channel instrument; µE1 beam; 15 – 60 MeVµ+ and µ-; 0 – 0.5 T, 0.3 – 400 K; high pressure < 15 kbar
Ø ALC: Avoided Level Crossing instrument; πE3 beam; 4 MeV µ+;Separator; 0 – 5 T, 4 – 600 K; integral counting
Ø LEM: Low Energy Muon beam & µSR instrument; πE3 beam (new µE4 beamunder commisioning); 0 – 30 keV µ+ ( controllable implantation depth 0 – 300 nm)0 – 0.3 T, 2.2 – 700 K
Paul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course / 25th-Feb-2005 / T. Prokscha
PAUL SCHERRER INSTITUT
GPS
General Purpose Surface muon instrument
Paul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course / 25th-Feb-2005 / T. Prokscha
PAUL SCHERRER INSTITUT
Muons On Request(MORE)
Ø GPS “tells” Kicker to send a muon toGPS
Ø If a muon is detected in GPS “tell”Kicker to send the beam to LTF
Ø no random beam background in GPS
Ø if decay e+ is detected in GPS the next muon is requested from theKicker
Paul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course / 25th-Feb-2005 / T. Prokscha
PAUL SCHERRER INSTITUT
MORE II:
Paul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course / 25th-Feb-2005 / T. Prokscha
PAUL SCHERRER INSTITUT
MORE in UPt3
• Two Knight shift components
• Dramatic and opposite Tdependence around TN (6K)
• UPt3 is intrinsically inhomogenous
A. Yaouanc et al, PRL84, 2702 (2000).
Paul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course / 25th-Feb-2005 / T. Prokscha
PAUL SCHERRER INSTITUT
MORE: Condon domains in Sn
G.Solt, V.S.Egorov, Physica B318, 2002 G.Solt, V.S.Egorov et al., Phys.Rev.B62, 2000
ν1 = 353.17 MHz ν2 = 353.25 MHz∆ν = 80 kHz !
need good time resolutionand small background
ð MORE
Condon domains are manifestations ofthe collective behaviour of electronsin quantized cyclotron orbits (Landau states)
Paul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course / 25th-Feb-2005 / T. Prokscha
PAUL SCHERRER INSTITUT
MORE: Condon domains in Be
G.Solt, V.S.Egorov et al., PSI, 2002
ν1 = 356.93 MHz ν2 = 357.32 MHz∆ν = 390 kHz !
Paul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course / 25th-Feb-2005 / T. Prokscha
PAUL SCHERRER INSTITUTVortex state of a superconductor
inside the solid:
Scanning
Tunneling
Microscop
Decoration
surface:
YBa2Cu3O6.95
T=10 K, Bext=0.1 T
-100 -50 50 100 0
B-Bext[G]
Four
iera
mpl
itude
Paul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course / 25th-Feb-2005 / T. Prokscha
PAUL SCHERRER INSTITUT
OsO6octahedra
Rb
•Superconductivity in the pyrochlore related oxide RbOs2O6R. Khasanov et al., PRL 93, 157004 (2004)
– Novel superconductor recently discovered RbOs2O6 Tc = 6.3KHiroi et al. cond-matt/0402006
– 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 INSTITUTRange of muons in matter
nm
mm
µm
102
10
1
1
102
10
1104103102101
Cu
Ran
ge
Energy [keV]
bulkthin films,multilayers..
§Allows depth-dependent µSR investigations ( ~ 1 – 300 nm)
§Extend the use of µSR to new objects of investigtions
§New magnetic/spin probe for thin films, multilayers,surface regions, buried layers,…
“Surface Muons” from π+
decay at rest ( ~ 4 MeV) generally used for condensed matter studiesfor bulk studies: no depth resolution
Paul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course / 25th-Feb-2005 / T. Prokscha
PAUL SCHERRER INSTITUTImplantation profiles of LE-µ
0 5 10 15 20 25 30 350
50
100
150
200RangeVariance
0 50 100 150 200
0,00
0,01
0,02
0,03
0,04
0,05
29.4 keV
24.9 keV20.9 keV
15.9 keV
6.9 keV
3.4 keV
Depth [nm]
Sto
pp
ing
Den
sity
Energy [keV]
nm
YBa2Cu3O7
YBa2Cu3O7
depth sensitive,microscopic,magnetic and spin probe
thin films, near surface regions, multi-layers, buried layers, nano cluster
(stopping profile calculated with Monte Carlo
code Trim.SP by W. Eckstein, MPI Garching,
Germany; see E.Morenzoni et al., NIM B192
(2002))
Paul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course / 25th-Feb-2005 / T. Prokscha
PAUL SCHERRER INSTITUTMuon moderation
1 10 102 103
Energy [keV]
Counts
/(ke
V 1
0
)9µ
20
40
60
1
Myonium
∼100 µm
surface muons ∼ 4 MeV∼ 100% polarised
∼300 nm s-Ne, s-Ar,... s-N26 K
∼100 µm
T. Prokscha et al, PRA 58, 3739 (1998)
N2
Kr
Xe
× 10
Ar
Spe
ktra
le D
icht
e [a
.u.]
Epithermische Myonen
[eV]0 25 50 75 100
10
20
30
40
50
[eV]0 25 50 75 100
[eV]0 25 50 75 100
[eV]0 25 50 75 100
10
20
30
40
50
10
20
30
40
50
10
20
30
40
50
Spe
ktra
le D
ichte
[a.u
.]
Energie Energie(known as good positron moderators)
Paul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course / 25th-Feb-2005 / T. Prokscha
PAUL SCHERRER INSTITUTMuon moderation II
surface muons∼ 4 MeV∼ 100% polarised
∼100 µm ∼300 nm s-Ne, s-Ars-N2
Time [ s]µ
Asy
mm
etry
Source of ∼ 15 eV 100% polarised muons
Mechanism:Suppression of energy lossdue to electronic excitationsin eV region in soft, perfectinsulators
Conversion efficiency: ∼10- 4
E. Morenzoni, F. Kottmann, D. Maden, B. Matthias, M. Meyberg, Th. Prokscha, Th. Wutzke, U. Zimmermann, Phys.Rev.Lett. 72, 2793 (1994).
Paul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course / 25th-Feb-2005 / T. Prokscha
PAUL SCHERRER INSTITUTThe PSI LEM beam
~3•107 µ+/s
~2800 µ+/s, Ne/N2
~1600 µ+/s, Ar/N2
~750 µ+/s, Ne @ 12kV
~670 µ+/s, Ar @ 20 kV
Polarized Low Energy Muon Beam ∼ 0.5-30 keV
Paul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course / 25th-Feb-2005 / T. Prokscha
PAUL SCHERRER INSTITUT
Paul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course / 25th-Feb-2005 / T. Prokscha
PAUL SCHERRER INSTITUTDepth dependent LE-µSR studies
B(z) superconductor
z
λ
àmagnetic field profile B(z)àCharacteristic lengths of the sc λ, ξ
muon implantation profile for a particularmuon energy Eµ
n(z,Eµ)
µSR experiment ⇒magnetic field probability distribution p(B) sensed by the muons
n(z)dz = p(B)dB ⇒ B(z)n(z)dz = p(B)dB ⇒ B(z)
Bext
♦♦♦♦
♦
♦
Paul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course / 25th-Feb-2005 / T. Prokscha
PAUL SCHERRER INSTITUTMagnetic field profiles in superconductors
ξ
ξ
λ
0
z
“local”
“non-local”
nonlocallocal
z
B(z)
)T(z
0abeB)z(B λ
−=→
à Direct Test of theories (London, BCS)
)T(nm
)T(s
*∝λ
à Direct, absolute measurement of magnetic penetration depth
ßeffective massßdensity of supercarriers
à Local, non-local response
à Determination of the coherence length ξ, and κ = λ/ξ
Paul Scherrer Institut • 5232 Villigen PSI Isis Muon Training Course / 25th-Feb-2005 / T. Prokscha
PAUL SCHERRER INSTITUTMagnetic field profiles in Pb and YBa2Cu3O7-δ
A. Suter, E. Morenzoni, R. Khasanov, H. Luetkens, T. Prokscha, andN. Garifianov, Phys. Rev. Lett. 92, 087001 (2004).
0 50 100 150
1E-3
0.01YBa
2Cu
3O
7-δ, T=20K, T
c=87.5K
hext
= 91.5(3) G, ξ0 = 1.5 nm fixed, λ0 = 137(10) nm
hext
exp(-z/ λ(T)) 3.4 keV 8.9 keV 15.9 keV 20.9 keV 29.4 keV
B (T
)z (nm)
0 50 100 150
1E-3
0.01
0 50 100 150
1E-3
0.01
0 50 100 150
1E-3
0.01Lead, T
c=7.0(2) K, h
ext = 91.5(3)G,
ξ0 = 90(5)nm, λ
0 = 58(3)nm
6.66K
6.19K
2.85K
z (nm)
B
(T
)
κ0 = 0.64(5) κ0 ≈ 90
non-local ßànon- exponential local ßà exponential
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)
KEK: pulsed (Tsukuba, Japan); JAERI/KEK J-Parc project at Tokai: 3 GeV/333µA pulsed beam, 25Hz, 80-100ns bunches, 2009
JINR: pulsed (Dubna, Russia)
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)