The DELPHI Silicon Tracker at LEP2 Chochula, P; Rosinský, P; Andreazza, A ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/1998, Letnik:
412, Številka:
2-3
Journal Article
Recenzirano
Odprti dostop
It is now considered that the information available in bibliographical databases is dated, validated through a long process which does not make it very innovative. Furthermore, database processing is ...normally performed using boolean operators : the results obtained from a query provides a sum of expected information which, in itself, does not deliver any novelty. Don Swanson's work demonstrates the unsuspected potential of bibliographical databases in revealing and discovering knowledge.The interest of his approach lies less on the available information itself than on the methodology used to disclose new knowledge. This general methodology fits perfectly well within an environment of validated and structured information, as is the case for bibliographical data. The expression Knowledge Discovery in Databases (KDD) indicates a methodology which creates new knowledge based upon bibliographical data. In this article, we will cover the principals of KDD based on Don Swanson's work as well as the method used to disclose knowledge within biomedical bibliographical databases.
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.
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.
The DELPHI Silicon Tracker at LEP2: The DELPHI Silicon Tracker Group Chochula, P; Rosinský, P; Andreazza, A ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
1998, Letnik:
412, Številka:
2
Journal Article
Recenzirano
The DELPHI Silicon Tracker, an ensemble of microstrips, ministrips and pixels, was completed in 1997 and has accumulated over
70
pb
−1
of high-energy data. The Tracker is optimised for the LEP2 ...physics programme. It consists of a silicon microstrip barrel and endcaps with layers of silicon pixel and ministrip detectors. In the barrel part, three-dimensional b tagging information is available down to a polar angle of 25°. Impact parameter resolutions have been measured of
28
μ
m
⊕
71/(p
sin
3/2
θ)
μ
m in
Rφ and
34
μ
m
⊕
69/p
μ
m in
Rz, where
p is the track momentum in GeV/
c. The amount of material has been kept low with the use of double-sided detectors, double-metal readout, and light mechanics. The pixels have dimensions of
330×330
μ
m
2 and the ministrips have a readout pitch of
200
μ
m. The forward part of the detector shows average efficiencies of more than 96%, has signal-to-noise ratios of up to 40 in the ministrips, and noise levels at the level of less than one part per million in the pixels. Measurements of space points with low backgrounds are provided, leading to a vastly improved tracking efficiency for the region with polar angle less than 25°.
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.
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) %.
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