The ratio of the total exclusive production cross sections for
η' and
η mesons has been measured in the
pp reaction at
p
beam=3.67 GeV/
c. The observed
η
′/
η ratio is (0.83±0.11
+0.23
−0.18)×10
−2 ...from which the exclusive
η
′ meson production cross section is determined to be (1.12±0.15
+0.42
−0.31) μb. Differential cross section distributions have been measured. Their shape is consistent with isotropic
η
′ meson production.
The total cross section of the reaction
pp→
ppK
+
K
− has been determined for proton–proton reactions with
p
beam
=3.67
GeV/c
. This represents the first cross section measurement of the
pp→
ppK
−
K
...+ channel near threshold, and is equivalent to the inclusive
pp→
ppK
−
X cross section at this beam momentum. The cross section determined at this beam momentum is about a factor 20 lower than that for inclusive
pp→
ppK
+
X meson production at the same CM energy above the corresponding threshold. This large difference in the
K
+ and
K
− meson inclusive production cross sections in proton-proton reactions is in strong contrast to cross sections measured in sub-threshold heavy ion collisions, which are similar in magnitude at the same energy per nucleon below the respective thresholds.
Design studies for a second generation dilepton spectrometer to be built at the SIS accelerator of GSI Darmstadt are presented. The basic design parameters of this system are specified and the ...different detector components for charged particle tracking and for lepton identification are described. The geometrical acceptance for lepton pairs is given. Results on single track momentum resolution and on lepton pair mass resolution are reported.
In a joint experiment the TAPS and CERES collaborations have studied the production of the neutral mesons and in 450 GeV p-Be and p-Au collisions at the CERN SPS. The mesons were identified by their ..., , and decay modes. The cross sections were measured down to very low ( 20 MeV/c) near mid-rapidity (). The and cross sections are smaller than expected from extrapolations of earlier data to low . Integrated over all , the ratios and / are lower by about 25% compared to previously published values. The reduction may be attributed to the large number of low pions from decays of heavier mesons. In addition, we have studied the dependence of neutral meson production on the mass of the nuclear target and find it in good agreement with previous measurements of charged mesons.
A magnetic spectrometer system has been constructed for the study of reactions with multiple charged particles in the final state, induced by polarized proton beams of few GeV energy. The system is ...based on a large-gap dipole magnet, with a liquid hydrogen target and scintillating fiber tracking detectors embedded inside the magnet. Multiwire proportional chambers, plastic scintillator hodoscopes, and threshold Cherenkov detectors placed outside the magnet provide additional tracking, triggering and particle identification capabilities. The system has been applied to study exclusive hyperon as well as pseudoscalar and vector meson production reactions at bombarding energies below 3
GeV. Additionally, it has been used to monitor the proton beam polarization at Laboratoire National Saturne. The components and performance of the system are reported.
DISTO data on K − p p Maggiora, M.; Kienle, P.; Suzuki, K. ...
Nuclear physics. A,
04/2010, Letnik:
835, Številka:
1
Journal Article
Recenzirano
The data from the DISTO Collaboration on the exclusive
p
p
→
p
K
+
Λ
production acquired at
T
p
=
2.85
GeV
have been re-analysed in order to search for a deeply bound
K
−
p
p
(
≡
X
)
state, to be ...formed in the binary process
p
p
→
K
+
X
. The
preliminary spectra of the
Δ
M
K
+
missing-mass and of the
M
p
Λ
invariant-mass show, for large transverse-momenta of protons and kaons, a distinct broad peak with a mass
M
X
=
2265
±
2
MeV
/
c
2
and a width
Γ
X
=
118
±
8
MeV
/
c
2
.
Exclusive $\eta$ production in pp reactions Fröhlich, I.; Balestra, F.; Bedfer, Y. ...
The European physical journal. A, Hadrons and nuclei,
11/2003, Letnik:
18, Številka:
2-3
Journal Article
Analyzing DISTO data of
pp
→
p
Λ
K
+
at
T
p
= 2.50 and 2.85GeV to populate a previously reported
X
(2265) -resonance with
M
x
= 2267 MeV/c
2
and Γ
x
= 118 MeV at 2.85GeV, we found that the yield of
X
...(2265) at 2.50GeV is much less than that at 2.85GeV (less than 10%), though it is expected from a kinematical consideration to be produced as much as 33% of that at 2.85GeV. The small population of
X
(2265) at 2.50GeV is consistent with the very weak production of Γ(1405) at the same incident energy toward its production threshold, thus indicating that Γ(1405) plays an important role as a doorway state for the formation of
X
(2265).
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