PINTEX Experiments
the three-nucleon force
CE80: spin correlation coefficients in p+d elastic scattering
The experiment used a vector and tensorpolarized deuteron target and
a polarized stored proton beam. Data have been taken at incident proton
energies of 135 and 200 MeV. The data are compared to Faddeev
calculations with and without three body force.
B. v.Przewoski, submitted to Phys. Rev. C
CE64: spin observables in pd breakup
Using a polarized deuteron beam and a polarized hydrogen target, pd breakup
was studied at 270 MeV deuteron energy (corresponds to 135 MeV protons). The
analysis of the data for the s0-called axial observables, that are parity-forbidden
in elastic scattering constituted the thesis topic of T.J. Whitaker.
Axial observables..., H.O. Meyer et al., submitted to Phys.
Rev. Lett.
pion production with polarized collision partners
ce44, ce64: neutral pion production in pp collisions
The original goal of this experiment was to measure the spin-dependent total cross
sections Deltasigma_T/sigma_tot and Deltasigma_L/sigma_tot, using A polarized internal
atomic hydrogen target and a stored, polarized beam. This is sufficient to determine
certain constraints on the partial waves of the reaction.
H.O. Meyer et al., Phys. Rev. Letters, 81, 3096 (1998)
H.O. Meyer et al., Phys. Rev. Lett. 83, 5439 (1999)
It was soon realized, that the experiment performed so well that all possible
polarization observables everywhere in pase space could be determined. A measurement
at four bombarding energies between 325 and 400 MeV then determines all partial
waves that are relevant in the frst 100 MeV above threshold.
H.O. Meyer et al., Phys. Rev. C63, 064002 (2001)
An interesting side-issue concerned the longitudinal analyzing power, measured either
with the target or the beam longitudinally polarized. This observables is zero by
parity conservation if there are only two particles in the final state. It turned
out that for pion production with a three-body final state, the longitudinal analyzing
power can be as large as the transverse one.
H.O. Meyer et al., Phys. Lett. B480, 7 (2000)
ce72, ce73: charged pion production in pp collisions
Concurrently with the observation of neutral pions, it was possible to also register
charged pion production. These reaction channels were the domain of the Pittsburgh
contingent, and Wilfried Daehnick worked on the analysis of these experiments until
his untimely death.
p+p -> p+n+pi+ :
Swapan K. Saha et al.,Phys. Lett. B461, 175 (1999)
W.W. Daehnick et al., Phys. Rev. C65, 024003 (2002)
p+p -> d+pi+ :
B. v. Przewoski et al., Phys. Rev. C61, 064604 (2000)
data: p+p -> d+pi+
ce79: pion production in pd collisions
This is a measurement of spin correlation coefficients in pd-->tpi+
between 220 and 270 MeV. The involvement of pion production with its
large momentum transfer would test the nuclear interaction at short
distances where three-nucleon effects should be largest.
Status: analysis (June 2004)
pp elastic scattering
A measurement of analyzing power\and spin correlation coefficients
in pp elastic scattering was the commissioning experiment for the PINTEX
setup, demonstrating that an internal polarized atomic target enhanced
by a storage cell is not only feasible, but makes measurements of spin
correlation parameters with unprecedented accuracy possible. The first
measurement (ce35) was limited to forward angles (4.5 - 17.5 degrees)
and one energy (200 MeV).
W. Haeberli et al., Phys. Rev. C 55 (1997) pp. 597-613
data: pp scattering (ce35)
Later, full angular distributions and a measurement of the Azz correlation
coefficient was added.
F. Rathmann, Phys. Rev. C58, 658 (1998)
B. Lorentz, Phys. Rev. C61, 054002 (2000)
After mastering the problems associated with changing the energy of a stored
polarized beam, the energy range from 200 to 450 MeV was mapped out (ce42).
B.v. Przewoski, Phys. Rev. C58, 1897 (1998)
data: pp scattering (ce42)
A new mathemtical method, based on 'diagonal scaling' was invented to reduce
the measured yields to the observables.
H.O. Meyer, Phys. Rev. C 56, 2074 (1997)
polarization of the stored beam
polarization calibration
The knowledge of the polarization of stored protons was based on a single, well-measured
analizing power in pp scattering. This calibration point was measured concurrently
with p+12C scattering. At the calibration energy p+12C scattering exhibits a
point in energy and angle where the analyzing power is exactly unity, which can
be used as an absolute reference.
B. von Przewoski, Phys. Rev. C44, 44 (1991)
Exporting the calibration to all beam energies accessible in a ring is another
benefit of the storage ring environment.
R.E. Pollock, Phys. Rev. E55, 7606 (1997)
polarization lifetime
Usually, the lifetime of the polarization of the stored beam is much longer than
the lifetime of the beam itself. Near a depolarizing resonance, however, polarization
lifetime becomes measurable. This was studied for an intrinsic resonance (ce55), as well
as for an induced (by an RF solenoid) resonance.
H.O. Meyer, Phys. Rev. E56, 3578 (1997)
B.v.Przewoski, Review of Scientific Instruments 69, 3146 (1998)
lifetime of vector and tensor polarization
Interestingly, the lifetime of the tensor and vector polarization of a stored deuteron
beam is not the same. This was studied with a deuteron beam that had both kinds of
polarization at the same time.
B. v.Przewoski, Phys. Rev. E68, 046501 (2003)
polarization of the target
CE70: polarized molecules?
The atoms in a polarized target recombine to some degree. Do the resulting molecules
retain some polarization? (the answer is yes). This was studied in a dedicated
experiment, nicknamed 'polmol'.
T. Wise, Phys. Rev. Lett. 87, 042701 (2001)
spin exchange in dense, polarized deuterium gas
In a dense deuterium target collisions between the target atoms leads to spin exchange
which in turn may affect the polarization of the target. This effect is significant
for tensor polarization and has been observed during ce80.
B. v.Przewoski, Phys. Rev. A68, 042705 (2003)
storage cell in ring
Test of a Windowless Storage Cell Target in a Proton Storage Ring
M.A. Ross, Nucl. Instr. Meth. A326, 424 (1993)
Performance of a Polarized-Hydrogen Storage Cell Target
M.A. Ross, Nucl. Instr. Meth. A344, 307 (1994)
Effect of a Polarized Hydrogen Target on the Polarization of a Stored Proton Beam
H. O. Meyer, Phys. Rev. E50, 1485 (1994)
Last modified: June 2004 by H.O. Meyer