P. Hautle, Santa Fe Polarized Drell-Yan Physics Workshop, Nov 2010 AFP – a fast & easy AFP – a fast & easy nuclear polarization nuclear polarization reversal ? reversal ? P. Hautle Paul Scherrer Institut CH-5232 Villigen PSI Switzerland Santa Fe Polarized Drell-Yan Physics Workshop October 31- November 1, 2010 Santa Fe, NM 87501, USA
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P. Hautle, Santa Fe Polarized Drell-Yan Physics Workshop, Nov 2010 AFP – a fast & easy nuclear polarization reversal ? P. Hautle Paul Scherrer Institut.
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P. Hautle, Santa Fe Polarized Drell-Yan Physics Workshop, Nov 2010
AFP – a fast & easy AFP – a fast & easy nuclear polarization nuclear polarization
reversal ?reversal ?P. Hautle
Paul Scherrer InstitutCH-5232 Villigen PSI
Switzerland
Santa Fe Polarized Drell-Yan Physics WorkshopOctober 31- November 1, 2010
Santa Fe, NM 87501, USA
P. Hautle, Santa Fe Polarized Drell-Yan Physics Workshop, Nov 2010
OutlineOutline
Introduction polarised targets = unique DNP systems
Overview of Experimental Data overview of experimental data
some details / comments
AFP Theory thermodynamic of a nuclear spin system
classical picture - rotating frame
quantum statistical description – spin temperature
which effects set limits on the optimum efficiency
Implementation technical and physics constraints
what can be expected
P. Hautle, Santa Fe Polarized Drell-Yan Physics Workshop, Nov 2010
PSI East
PSI West
Aare
SLS
cw Proton accelerator (590 MeV, 2.2 mA)
(, , SR SINQ, UCN)
SwissFEL
Accelerator Facilities
P. Hautle, Santa Fe Polarized Drell-Yan Physics Workshop, Nov 2010
100 cm100 cm33
„„Frozen Spin“ Frozen Spin“ Polarised Polarised
TargetTarget
Particle physics experimentson beams of pions, protons, neutrons…..
P. Hautle, Santa Fe Polarized Drell-Yan Physics Workshop, Nov 2010
60 μm thick polystyrene foil cooled to 200 mK by a sub micron thick film of superfluid 4He
cell with two 500 nm thick Si3Ni4 windows
“Ultra-thin” polarised solid target
[J.P Urrego Blanco et al., NIM B 261 (2007) 1112]
P. Hautle, Santa Fe Polarized Drell-Yan Physics Workshop, Nov 2010
suppress background suppress background scattering by TOFscattering by TOF
coincident coincident in situin situ detection of low detection of low energy recoil protons energy recoil protons in the target itselfin the target itself
polarisedpolarised nuclei in nuclei in the the scintillatingscintillating detector itselfdetector itself
O
N
HC
HC
n
CH3
O
CH3
CH3
CH3
N·B. van den Brandt B. van den Brandt et al.,et al., NIM A 446 (2000) 592 NIM A 446 (2000) 592
P. Hautle, Santa Fe Polarized Drell-Yan Physics Workshop, Nov 2010
BeamBeamDetector
neutron beamneutron beam
Observe DNP build up with Observe DNP build up with
small angle neutron scatteringsmall angle neutron scatteringthrough spin contrast variation
Europhys. Lett. 59 (2002) 62 Eur. Phys. J. B 49 (2006) 157–165J. Appl. Cryst. 40 (2007) s106-s110
P. Hautle, Santa Fe Polarized Drell-Yan Physics Workshop, Nov 2010
BB00=2.5T=2.5T
58
mm
58
mm
d-PS targetd-PS targetdoped with d-TEMPOdoped with d-TEMPO
Ø Ø 5 mm x 1.2 mm5 mm x 1.2 mm
66LiFLiF
targettargetholderholder
45 mm45 mm
Pseudomagnetic precession of cold Pseudomagnetic precession of cold neutronsneutrons
[F. M. Piegsa et al., NIM A 611 (2009) 231]
P. Hautle, Santa Fe Polarized Drell-Yan Physics Workshop, Nov 2010
Dissolution DNP for MRI / NMRDissolution DNP for MRI / NMR
Polarize organic samples labeled with 13C, 6Li, 15N nuclei in solid state (1 K / 5T)
Dissolve rapidly and inject into rat in imager (9.4 T) => image of brain metabolismimage of brain metabolism
Details and List of publications see: http//: sdnpi.epfl.ch
P. Hautle, Santa Fe Polarized Drell-Yan Physics Workshop, Nov 2010
Entropy transferred from polarizationpolarization to spin-spin orderingspin-spin ordering
Reversibility:Reversibility: change of H0 slow compared to equilibration time (HL)1
P. Hautle, Santa Fe Polarized Drell-Yan Physics Workshop, Nov 2010
Adiabatic fast Adiabatic fast passage (AFP)passage (AFP)
P. Hautle, Santa Fe Polarized Drell-Yan Physics Workshop, Nov 2010
rf field - Rotating frame of referencerf field - Rotating frame of reference[F. Bloch, Phys Rev 70 (1946) 460]
[A. Abragam, Principles of Nuclear Magnetism, 1961]
rotating framerotating frame
0 1 1ˆ ˆcos( ) sin( )ˆH H z H t x H t y
External field H
contains rf fieldrf field
0 1 ˆ( ) ˆ re rH z HH x
1 1
0 0
tan( )
H
H
0 0H Larmor frequency:
0zH H 12 cos( )xH H tstatic field: rf field:
H1
He
H0 ω/γ
H0rz z
rx
M
M
P. Hautle, Santa Fe Polarized Drell-Yan Physics Workshop, Nov 2010
rf field - Rotating frame of referencerf field - Rotating frame of reference[F. Bloch, Phys Rev 70 (1946) 460]
[A. Abragam, Principles of Nuclear Magnetism, 1961]
rotating framerotating frame
0 1 1ˆ ˆcos( ) sin( )ˆH H z H t x H t y
External field H
contains rf fieldrf field
0 1 ˆ( ) ˆ re rH z HH x
1 1
0 0
tan( )
H
H
0 0H Larmor frequency:
0zH H 12 cos( )xH H tstatic field: rf field:
H1
He
H0 ω/γ
H0rz z
rx
M
M
HHee can be rotated by 180° can be rotated by 180°
sweeping sweeping HH00 or or ω ω through through resonance resonance
P. Hautle, Santa Fe Polarized Drell-Yan Physics Workshop, Nov 2010
Adiabatic TheoremAdiabatic Theoremd
Hdt
equation of motion
For any vector satisfying a similar equation of motion the angle For any vector satisfying a similar equation of motion the angle between and remains constant provided the change of between and remains constant provided the change of direction of in time is sufficiently slowdirection of in time is sufficiently slow
H H
Possible to reverse the magnetization
What happens to the magnetization ? M
21
dHH
dtAdiabaticAdiabaticity: FastFaster than relaxation: 1
1H
P. Hautle, Santa Fe Polarized Drell-Yan Physics Workshop, Nov 2010
Adiabatic TheoremAdiabatic Theoremd
Hdt
equation of motion
For any vector satisfying a similar equation of motion the angle For any vector satisfying a similar equation of motion the angle between and remains constant provided the change of between and remains constant provided the change of direction of in time is sufficiently slowdirection of in time is sufficiently slow
H H
Possible to reverse the magnetization
2 2 212 /e LR SS C H H T constantconstant
What happens to the magnetization ? M
Thermodynmics in Thermodynmics in solidsolid sample sample
Adiabtic demagnetization in the rotating frame (ADRF) Isentropic passageIsentropic passage
Important change when He
HLR :
Entropy transferred from polarizationpolarization to spin-spin orderingspin-spin ordering
((Zeeman Zeeman toto dipolar ordering dipolar ordering))
21
dHH
dtAdiabaticAdiabaticity: FastFaster than relaxation: 1
1H
P. Hautle, Santa Fe Polarized Drell-Yan Physics Workshop, Nov 2010
Frequency [MHz]149.0 149.2 149.4 149.6 149.8 150.0
( )g
Estimate the losses -Estimate the losses -AFP in the spin temperature modelAFP in the spin temperature model
[M. Goldman et al., Phys Rev 168 (1968) 301]
1 LH H
( ) 1g d
Provotorov equations describe mixing between Zeeman and spin-spin subsystem:
0H
Conditions:
High temperatures
Low nuclear polarizations
2 21( ) ( )W H g Mixing rate:Mixing rate:
AFPAFP:: variation of very small during time T2 D
12
W T
2 2
/ ( )
/ ( / )( )
d dt W
d dt W D
Evolution of inverse spin temperatures and to common value
P. Hautle, Santa Fe Polarized Drell-Yan Physics Workshop, Nov 2010
Frequency [MHz]149.0 149.2 149.4 149.6 149.8 150.0
( )g
Sweep of field / frequency through the Sweep of field / frequency through the resonanceresonance
121expfinal
initial
PP H dH dt
P
Fast sweepFast sweep – in time much shortershorter than mixing time W1