The KLOE drift chamber Andryakov, A; Antonelli, A; Baldini-Ferroli, R ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/1996, Letnik:
379, Številka:
3
Journal Article
Recenzirano
The stringent requirements of the KLOE experiment on dimensions, efficiency, resolution and transparency of its drift chamber led to building a tracking device which can be considered innovative from ...many points of view.
Details of the design and construction of this detector, together with preliminary results from the test of its full scale prototype, constructed and operated under a test beam at CERN, are presented and discussed.
Using the ARGUS detector at the e
+e
− storage ring DORIS II at DESY, we have searched for decays
b →
s
gluon through full reconstruction of a whole event. Two B
B
decays were found with one of B ...meson decaying into a final state without charmed particles. We also obtained an upper limit of
Br(B
+ →
τ
+
ν
τ
) of 1.04% at 90%
CL.
Using the ARGUS detector at the
e
+
e
− storage ring DORIS II, we have measured the semileptonic branching ratios of the
D
0 meson to be
Br(
D
0 →
e
+
ν
e
X) = (6.9 ± 0.3 ± 0.5) % and
Br(
D
0 →
μ
+
ν
...μ
X) = (6.0 ± 0.7 ± 1.2) %, and the semileptonic branching ratio of the charmed hadron mixture from
e
+
e
− annihilation around 10 GeV to be
Br(
c →
e
+
ν
e
X) = (9.6 ± 0.4 ± 1.1) %.
Using the ARGUS detector at the
e
+
e
− storage ring DORIS II at DESY, we have found evidence for the production of the excited charmed baryon state
Λ
c
(2593)
+ in the channel
Λ
c
+
π
+
π
−. Its ...mass was determined to be (2594.6±0.9±0.4) MeV/c
2, and the natural width measured to be Γ = (2.9
−2.1−1.4
+2.9+1.8) MeV. The production cross section times the branching ratios of
σ(
e
+
e
− →
Λ
c
(2593)
+
X) ×
Br(
Λ
c
(2593)
+ →
Λ
c
+
π
+
π
−) ×
Br(
Λ
c
+ →
pK
−
π
+) was measured to be (0.25
−0.13
+0.24 ±0.13) pb. The fractions of
Λ
c
(2593)
+ decays proceeding through the
Σ
c
0
π
+ and
Σ
c
++
π
− channels were determined to be 0.29±0.10±0.11 and 0.37±0.12±0.13, respectively.
Using the ARGUS detector at the
e
+
e
− storage ring DORIS II, we have measured the Michel parameters
ρ,
ξ, and
ξδ for
τ
±→l
±ν
ν
̄
decays in
τ-pair events produced at center of mass energies in the ...region of the
ϒ resonances. Using
τ
∓→
ρ
∓
ν as spin analyzing tags, we find
ρ
e
=0.68±0.04±0.08,
ξ
e
=1.12±0.20±0.09,
ξδ
e
=0.57±0.14±0.07,
ρ
μ
=0.69±0.06±0.08,
ξ
μ
=1.25±0.27±0.14 and
ξδ
μ
=0.72±0.18±0.10. In addition, we report the combined ARGUS results on
ρ,
ξ, and
ξδ using this work und previous measurements.
Using the ARGUS detector at the
e
+
e
− storage ring DORIS II, we have determined the Michel parameters ξ and δ of
τ
∓ → l
∓ν
ν
-
decays. With an integrated luminosity of 445 pb
−1 around
s
= 10
GeV, ...we have produced approximately 415000 τ-pairs. From this data sample, 3262 events were selected with
e
+e
− → τ
+τ
− → (l
±ν
ν
-
) (π
∓π
+π
−ν)
. The semihadronic decay was used as analyser of the τ-spin and made possible - owing to the spin correlations - the determination of the parity-violating Michel parameters ξ and δ in the decay
τ
∓ → l
∓ν
ν
-
. Simultaneously to the determination of the Michel parameters, a measurement of the τ-neutrino helicity
h
ν
τ
in the decay
τ
∓ →
π
∓
π
+
π
−
ν was obtained. We observed
h
ν
τ
= −0.85
−0.17
+0.15 ± 0.05,
ϱ = 0.721 ± 0.040 ± 0.021,
ξ = 1.26
−0.26
+0.30 ± 0.09, and
ξδ = 0.77
−0.16
+0.18 ± 0.05. In addition, the combined ARGUS result on
h
ν
τ
, ϱ, ξ, and ξδ are reported using this work and previous measurements.
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