mitglied der helmholtz-gemeinschaft spin physics at storage rings april 11, 2015 frank rathmann...
TRANSCRIPT
Mit
glie
d d
er
Helm
holt
z-G
em
ein
sch
aft
Spin physics at Storage Rings
April 11, 2015 Frank Rathmann
Barschall/Haeberli Symposium, Madison
Spin Physics at Storage Rings 2
My first contact with Willy
Workshop on Polarized Gas Targets, Heidelberg, Fall 1991
Kisten Zapfe
Willy
Erhard Steffensme
Spin Physics at Storage Rings 3
1992: The first spin filtering experiment at HD
Before Willy came, it was clear to everyone (students and professors alike) that we would measure the target polarization using elastic scattering. Within a day after Willy had inspected the equipment and the anticipated measurements, it became clear that this would simply not work! The analyzing power of scattering () exceeds the one of pp scattering by about a factor 100, so we did dedicated runs with stored particles to determine the target polarization.
The apparatus was there,
TSR
and the target and polarimeter
Goal: Produce a beam of polarized antiprotons
Spin Physics at Storage Rings 4
1992: Preparation of the storage cells
The openable cell had been developed because accelerator physicists were cautions about obstructions. But this cell showed a much smaller target polarization than expected. Eventually the machine people learned how to inject and cool the beam in the presence of a closed cell.
FEP 1200.2 mm Al
FEP 1200.2 mm Al
TPFE 31700.2 mm Al
improvized spot welding
Spin Physics at Storage Rings 5
2011: Spin filtering at COSY
In 2009, the PAX collaboration submitted a proposal for spin filtering studies using antiprotons at the AD, and the SPSC of CERN requested another spin filtering experiment with protons.
Measured spin-dependent cross section fully consistent with NN scattering.
W. Augustyniak et al., Phys. Lett. B 718 (2012)
After the results were published, the SPSC concluded that spin filtering experiments would not fit into the present AD program.
F. Rathmann et al., Phys.Rev.Lett. 71 (1993)
Spin Physics at Storage Rings 6
1994: Move to Madison
After my PhD in January 1994, Willy offered me a PostDoc position at UW.
In May 1994, I came to Madison on a Fellowship of the Alexander von Humboldt Foundation.
In July 1994, my wife Andrea, 2 year Isabel and ¾ year Leonard followed.
Willy and Gabi greatly supported us in all relevant aspects.
Our years in Madison (1994 – 1997) were just fantastic.
Spin Physics at Storage Rings 7
1994-2003: Experiments at the Indiana Cooler
elastic scattering: Almost free of background, complete angular distributions, spin
correlations , , , and , lateron we also measured using longitudinal beam polarization. Very small normalization uncertainties, and very small statistical errors. This was real fun!
How long does it take to reverse the target polarization?
𝜏=7±1ms
W. Haeberli et al., Phys. Rev. C 55 (1997)F. Rathmann et al., Phys. Rev. C 58 (1998)B. von Przewoski et al., Phys. Rev. C 58 (1998)B. Lorentz et al., Phys. Rev. C 61 (2000)
Spin Physics at Storage Rings 8
1994-2003: Experiments at the Indiana Cooler
Nuclear polarization of Hydrogen Molecules: Experiment used a storage ring to measure the nuclear polarization
of molecules formed by recombination of Hydrogen atoms in a cell.
entrance tube
200 MeV proton beam
Teflon coatedtarget cell
Teflon valve
Copperrecombiner
superconductingcurrent loop
atomic beam
T. Wise et al., Phys. Rev. Lett. 87 (2001).
Fac
tion
of p
roto
n po
lariz
atio
n re
tain
ed in
mol
ecul
es
Spin Physics at Storage Rings 9
2000 - present: Jülich
Nuclear polarization of Hydrogen Molecules: Since then, these studies were continued in Jülich. A new device
was built making this possible without an accelerator.
superconducting solenoid
• Glas cell cover by a gold surface• Additional covering by Teflon, Fomblin, etc.• Crucial: Can be heated to 400 C
This effort started after a continental breakfast with Willy at the Hampton Inn in Bloomington, IN (~1999) during a run at the Indiana Cooler. Back in Jülich we started to develop the device, together with our colleagues from Gatchina, Russia.
Spin Physics at Storage Rings 10
2000 - present: Jülich
Nuclear polarization of Hydrogen Molecules: The Jülich polarized ABS was used during time periods, when
we are not running the storage ring experiments
The polarized ABS on its way into the internal target station. Device was designed to do that within a maintenance week.
Off beam installationInstallation at the ANKE magnet
spectrometer spectrometer at COSY
Spin Physics at Storage Rings 11
2000 - present: Jülich
Nuclear polarization of Hydrogen Molecules: Recent progress
preliminary
T=100 K
Because of the superconducting solenoid, there is very little water in the vaccum vessel. The results shown here are achieved with a clean surface during one day.
Spin Physics at Storage Rings 12
Willy, I always enjoy working with you.
I wish you all the best
Valerie, one of the Wisonsin souvenirs we took back to Germany.