Polarized gas targets Rathmann, Frank
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
01/2005, Letnik:
536, Številka:
3
Journal Article
Recenzirano
Polarized internal gas targets are operated at various electron and proton machines reaching luminosities of
10
31
and
10
29
cm
-
2
s
-
1
, respectively. The present paper focuses on experimental ...aspects, such as the design and construction of storage cells, and different methods employed for polarimetry.
.
The reaction
p
+
d
→
p
+
d
+
X
was studied at 0.8-2.0 GeV proton beam energies with the ANKE magnetic spectrometer at the COSY synchrotron storage ring. The proton-deuteron pairs emerging with high ...momenta, 0.6-1.8 GeV/
c
, were detected at small angles with respect to the proton beam. Distribution over the reaction missing mass
M
x
reveals a local enhancement near the threshold of the pion pair production specific for the so-called ABC effect. The enhancement has a structure of a narrow bump placed above a smooth continuum. The invariant mass of the
d
π
π
system in this enhancement region exhibits a resonance-like peak at
M
d
π
π
≈
2
.
36
GeV/
c
2
with the width
Γ
≈
0
.
10
GeV/
c
2
. A possible interpretation of these features is discussed.
A New Application of a Lamb-shift Polarimeter Engels, R; Grigoryev, K; Mikirtychyants, M ...
PSTP 2007 (AIP Conference Proceddings Volume 980),
01/2008, Letnik:
980
Journal Article
Recenzirano
With the use of a spinfilter as the most important component of a Lamb-shift polarimeter, a beam of metastable atoms in one hyperfine state (alpha1 or alpha2) can be produced. By induced transitions ...it seems possible to observe any transition between the 2S1/2 metastable hyperfine states or into the short-lived states 2P1/2 and 2P3/2 of the hydrogen (deuterium) atom separately as a function of the magnetic field. According to our estimate, the Breit-Rabi diagrams for these states can be measured with a precison of about 1 kHz (4.2X10-12 eV) or even better. Furthermore, the hyperfine splittings and the Lamb shift can be observed as well.
The nucleon–nucleon interaction (NN) is fundamental for the whole of nuclear physics and hence to the composition of matter as we know it. It has been demonstrated that stored, polarised beams and ...polarised internal targets are experimental tools of choice to probe spin effects in NN–scattering experiments. While the EDDA experiment has dramatically improved the proton–proton date base, information on spin observables in neutron–proton scattering is very incomplete above 800 MeV, resulting in large uncertainties in isoscalar n p phase shifts. Experiments at COSY, using a polarised deuteron beam or target, can lead to significant improvements in the situation through the study of quasi–free reactions on the neutron in the deuteron. Such a measurements has already been started at ANKE by using polarised deuterons on an unpolarised target to study the dp → {pp}n deuteron charge–exchange reaction and the full program with a polarised storage cell target just has been conducted. At low excitation energies of the final pp system, the spin observables are directly related to the spin– dependent parts of the neutron–proton charge–exchange amplitudes. Our measurement of the deuteron–proton spin correlations will allow us to determine the relative phases of these amplitudes in addition to their overall magnitudes.
In the framework of the FAIR project 1, the PAX collaboration 2 has suggested new experiments using polarized protons and antiprotons. In order to provide polarized antiprotons, the polarization ...buildup by spin-dependent attenuation due to nuclear interaction (spin-filtering) must be studied. The goal of these investigations is to understand the physics of the spin-filtering process with stored protons at COSY, and to shed light on the role of polarized electrons for the polarization buildup. Later on, the spin-dependence of the proton-antiproton interaction will be investigated at the Antiproton Decelerator ring (AD) of CERN. In order to carry out these investigations, a storage ring section has to be developed which minimizes the spin-independent losses due to single Coulomb scattering.
We investigated coherent betatron oscillations of a deuteron beam in the storage ring cooler synchrotron and storage ring, excited by a detuned rf Wien filter (WF). The beam oscillations were ...detected by conventional beam position monitors. With the currently available apparatus, we show that oscillation amplitudes down to1μmcan be detected. The interpretation of the response of the stored beam to the detuned rf WF is based on simulations of the beam evolution in the lattice of the ring and realistic time-dependent 3D field maps of the WF. Future measurements of the electric dipole moment of protons will, however, require control of the relative position of counter-propagating beams in the sub-picometer range. Since here the stored beam can be considered as a rarefied gas of uncorrelated particles, we moreover demonstrate that the amplitudes of the zero-point (ground state) betatron oscillations of individual particles are only a factor of about 10 larger than the Heisenberg uncertainty limit. As a consequence of this, we conclude that quantum mechanics does not preclude the control of the beam centroids to sub-picometer accuracy. The smallest Lorentz force exerted on a single particle that we have been able to determine is 10 aN.
PDF
