The DEPFET collaboration develops highly granular, ultra-transparent active pixel detectors for high-performance vertex reconstruction at future collider experiments. The characterization of detector ...prototypes has proven that the key principle, the integration of a first amplification stage in a detector-grade sensor material, can provide a comfortable signal to noise ratio of over 40 for a sensor thickness of 50-75 μm. ASICs have been designed and produced to operate a DEPFET pixel detector with the required read-out speed. A complete detector concept is being developed, including solutions for mechanical support, cooling, and services. In this paper, the status of the DEPFET R & D project is reviewed in the light of the requirements of the vertex detector at a future linear e + e - collider.
We perform a full amplitude analysis of the process e+e−→J/ψDD¯, where D refers to either D0 or D+. A new charmoniumlike state X*(3860) that decays to DD¯ is observed with a significance of 6.5σ. Its ...mass is (3862−32+26 −13+40) MeV/c2, and its width is (201−67+154 −82+88) MeV. The JPC=0++ hypothesis is favored over the 2++ hypothesis at the level of 2.5σ. The analysis is based on the 980 fb−1 data sample collected by the Belle detector at the asymmetric-energy e+e− collider KEKB.
We present the first measurements of absolute branching fractions of Ξc0 decays into Ξ−π+, ΛK−π+, and pK−K−π+ final states. The measurements are made using a dataset comprising (772±11)×106 BB¯ pairs ...collected at the ϒ(4S) resonance with the Belle detector at the KEKB e+e− collider. We first measure the absolute branching fraction for B−→Λ¯c−Ξc0 using a missing-mass technique; the result is B(B−→Λ¯c−Ξc0)=(9.51±2.10±0.88)×10−4. We subsequently measure the product branching fractions B(B−→Λ¯c−Ξc0)B(Ξc0→Ξ−π+), B(B−→Λ¯c−Ξc0)B(Ξc0→ΛK−π+), and B(B−→Λ¯c−Ξc0)B(Ξc0→pK−K−π+) with improved precision. Dividing these product branching fractions by the result for B−→Λ¯c−Ξc0 yields the following branching fractions: B(Ξc0→Ξ−π+)=(1.80±0.50±0.14)%, B(Ξc0→ΛK−π+)=(1.17±0.37±0.09)%, and B(Ξc0→pK−K−π+)=(0.58±0.23±0.05)%. For the above branching fractions, the first uncertainties are statistical and the second are systematic. Our result for B(Ξc0→Ξ−π+) can be combined with Ξc0 branching fractions measured relative to Ξc0→Ξ−π+ to yield other absolute Ξc0 branching fractions.
We search for lepton-flavor and lepton-number-violating I decays into a lepton (a= electron or muon) and two charged mesons (h , h a2 = pi +/- or K +/-) using 854 fb - 1 of data collected with the ...Belle detector at the KEKB asymmetric-energy e + e - collider. We obtain 90% confidence level upper limits on the I a a h h a2 branching fractions in the range (2.0 a 8.4) X 10 - 8 . These results improve upon our previously published upper limits by factors of about 1.8 on average.
Using a data sample of 980 fb−1 of e+e− annihilation data taken with the Belle detector operating at the KEKB asymmetric-energy e+e− collider, we report the results of a study of excited Ξc states ...that decay, via the emission of photons and/or charged pions, into Ξc0 or Ξc+ ground state charmed-strange baryons. We present new measurements of the masses of all members of the Ξc′, Ξc(2645), Ξc(2790), Ξc(2815), and Ξc(2980) isodoublets, measurements of the intrinsic widths of those that decay strongly, and evidence of previously unknown transitions.
Using a data sample of 921.9 fb-1 collected with the Belle detector, we study the process of $e^+e^- → D^+_s D_{s1}(2536)^-+c.c.$ via initial-state radiation. We report the first observation of a ...vector charmoniumlike state decaying to $D^+_s D_{s1}(2536)^-+c.c.$ with a significance of $5.9σ$, including systematic uncertainties. The measured mass and width are $(4625.9^{+6.2}_{-6.0}$(stat)$±0.4$(syst)) MeV/$c_2$ and ($49.8^{+13.9}_{-11.5}$(stat)$±4.0$(syst)) MeV, respectively. The product of the $e^+e^- → D^+_s D_{s1}(2536)^-+c.c.$ cross section and the branching fraction of $D_{s1}(2536)^- → \bar{D}^{*0}K^-$ is measured from the $D_s \bar{D}_{s1}(2536)$ threshold to $5.59$ GeV.
DEPFET, a monolithic active pixel sensor for the ILC Velthuis, J.J.; Kohrs, R.; Mathes, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/2007, Letnik:
579, Številka:
2
Journal Article
Recenzirano
In a DEPleted Field Effect Transistor (DEPFET) sensor a MOSFET is integrated on a sidewards depleted p-on-n silicon detector, thereby combining the advantages of a fully depleted silicon sensor with ...in-pixel amplification. A 450
μm thick DEPFET was tested in a testbeam. The
S/
N was found to be larger than 110. The position resolution is better than 5
μm. At a seed cut of 7
σ, the efficiency and purity are both close to 100%. In the readout chip a zero-suppression capability is implemented. The functionality was demonstrated using a radio-active source. The predicted impact parameter resolution of a 50
μm thick DEPFET vertex detector, is much better than required for the International Linear Collider (ILC).
We report a measurement of the differential cross section of π^0 pair production in single-tag two-photon collisions, y*y->π^0π^0, in e+e- scattering. The cross section is measured for Q^2up to 30 ...GeV^2 is the negative of the invariant mass squared of the tagged photon
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