The status of the construction of the KLOE Drift Chamber is reviewed. With its 4m diameter, it will be the biggest drift chamber ever built. The stringing of 52000 wires is a titanic effort: details ...are given about the semiautomatic system, the quality tests on wires and the monitoring of end-plates deformations.
Using the detector ARGUS at the
e
+
e
− storage ring DORIS II at DESY, we have observed the decays
Λ
c
+ →
Ξ
−
K
+
π
+ and
Λ
c
+ → Ξ
∗0K
+
and obtained evidence for the decay
Ξ
c
0 →
ΛK
s
0. All ...three of these decays are of interest as they provide information about
W-exchange processes. The products of cross sections and branching ratios for
Λ
c
+ →
Ξ
−
K
+
π
+ and
Λ
c
+ → Ξ
∗0K
+
are (1.7±0.3±0.3) pb and (0.6±0.2±0.1) pb, respectively, which implies that (35±17) % of the
Ξ
−
K
+
π
+ final state is generated through a two-body decay via intermediate
W-exchange. The product of production cross section and branching ratio for
Ξ
c
0 →
Λ
K
s
0 is (2.1 ± 1.0 ± 0.6) pb.
Using the ARGUS detector at the
e
+
e
− storage ring DORIS II at DESY, we have studied lepton energy spectra in τ decays. We present a “pseudo-rest-frame” technique in which the second τ in the ...event, decaying into a heavy hadronic system, is used as reference. This method allows for the first measurement of the Michel Parameter η in τ decays. We also determine the Michel Parameter ρ in τ →
ev̄v decays with a precision comparable to the present world average. The measured values of the parameters ρ=0.735±0.036±0.020 and η=0.03±0.18±0.12 are in good agreement with standard V-A coupling at the τ-ν-W vertex.
Using the ARGUS detector at the
e
+
e
− storage ring DORIS II at DESY, we have made two measurements of the mixing parameter
χ
d
using kaons as flavour tags. Using
D
∗+ K
±
correlations we found
χ
d
...= 0.20 ± 0.13 ± 0.12 and from the study of
(D
∗+ℓ
−) K
±
correlations we obtained
χ
d
= 0.19 ± 0.07 ± 0.09. The branching ratio for
B → D
∗+ X
has been updated:
Br(
B → D
∗+ X) = (19.6 ± 1.9)
%. We have also determined the average multiplicity of charged kaons in
B
0 decays to be 0.78 ± 0.08.
Nucl.Instrum.Meth. A485 (2002) 477-489 The construction of a micro-pattern gas detector of dimensions 40x10 cm**2 is
described. Two gas electron multiplier foils (GEM) provide the internal
...amplification stages. A two-layer readout structure was used, manufactured in
the same technology as the GEM foils. The strips of each layer cross at an
effective crossing angle of 6.7 degrees and have a 406 um pitch. The
performance of the detector has been evaluated in a muon beam at CERN using a
silicon telescope as reference system. The position resolutions of two
orthogonal coordinates are measured to be 50 um and 1 mm, respectively. The
muon detection efficiency for two-dimensional space points reaches 96%.
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