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 report the analysis of the three-body e^{+}e^{-}→BBover ¯π^{±}, BBover ¯^{*}π^{±}, and B^{*}Bover ¯^{*}π^{±} processes, including the first observations of the Z_{b}^{±}(10610)→BBover ...¯^{*}+c.c.^{±} and Z_{b}^{±}(10650)→B^{*}Bover ¯^{*}^{±} transitions that are found to dominate the corresponding final states. We measure Born cross sections for the three-body production of σ(e^{+}e^{-}→BBover ¯^{*}+c.c.^{±}π^{∓})=17.4±1.6(stat)±1.9(syst) pb and σ(e^{+}e^{-}→B^{*}Bover ¯^{*}^{±}π^{∓})=8.75±1.15(stat)±1.04(syst) pb and set a 90% C.L. upper limit of σ(e^{+}e^{-}→BBover ¯^{±}π^{∓})<2.9 pb. The results are based on a 121.4 fb^{-1} data sample collected with the Belle detector at a center-of-mass energy near the ϒ(10860) peak.
The aim of our study is to explore the spinal excitability through the electrophysiological evaluation of patients affected by primitives Restless Legs Syndrome (RLS). 15 women affected by primitive ...RLS were compared with age-matched healthy females. All subjects underwent ENG evaluation: nerve conduction studies (NCS), F waves parameters (minimum, mean and maximum latency, duration, amplitude, persistency and the ratio between F wave duration (FWD) and the duration of the corresponding compound muscle action potential (FWD/CMAPD), and the Cutaneous Silent Period parameters (latency, duration and the ratio between duration at low to upper extremities). None of the subjects included in our study showed alterations in the NCS. Compared to the control group, RLS patients showed significantly higher values of the FWD for both ulnar ( p < 0.05) and tibial ( p < 0.01) nerves and for the FWD/CMAPD ratio ( p < 0.001). The results of our study indicate a widespread spinal motoneuronaI hyper-excitability that could be mainly due to an altered modulation within the interneuronal system. Presently, RLS diagnosis is based exclusively on clinical criteria. The FWD/CMAPD ratio can help to shed light on the pathogenesis of RLS, and can represent an objective, easily obtainable, diagnostic tool especially in cases of evening lower leg discomfort of unclear interpretation.
We report inclusive and exclusive measurements for χc1 and χc2 production in B decays. We measure B(B → χc1X)= (3.03 ± 0.05(stat) ± 0.24(syst)) × 10$-$3 and B(B → χc2X)= (0.70 ± 0.06(stat) ± ...0.10(syst)) × 10$-$3 . For the first time, χc2 production in exclusive B decays in the modes B0 → χc2π $-$K+ and B+ → χc2π+π$-$K+ has been observed, along with first evidence for the B+ → χc2π+K$0\atop{S}$ decay mode. For χc1 production, we report the first observation in the B+ → χc1π+π$-$K+, B0 → χc1π+π$-$K$0\atop{S}$ and B0 → χc1π0π$-$K+ decay modes. Using these decay modes, we observe a difference in the production mechanism of χc2 in comparison to χc1 in B decays. In addition, we report searches for X(3872) and χc1(2P) in the B+ → (χc1π+π$-$)K+ decay 3 mode. The reported results use 772 × 106 B$\overline{B}$ events collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e$-$ collider.
Commissioning and performance of the Belle II pixel detector Ye, H.; Abudinen, F.; Ackermann, K. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
01/2021, Letnik:
987
Journal Article
Recenzirano
The Belle II experiment at the SuperKEKB energy-asymmetric e+e− collider has completed a series of substantial upgrades and started collecting data in 2019. The experiment is expected to accumulate a ...data set of 50 ab−1 to explore new physics beyond the Standard Model at the intensity frontier. The pixel detector (PXD) of Belle II plays a key role in vertex determination. It has been developed using the DEpleted P-channel Field Effect Transistor (DEPFET) technology, which combines low power consumption in the active pixel area and low intrinsic noise with a very small material budget. In this paper, commissioning and performance of the PXD measured with first collision data are presented.
Belle II pixel detector: Performance of final DEPFET modules Paschen, B.; Abudinen, F.; Ahlburg, P. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2020, Letnik:
958
Journal Article
Recenzirano
A DEpleted P-channel Field Effect Transistor (DEPFET) based pixel detector was developed for the Belle II VerteX Detector (VXD). It is designed to achieve a good impact parameter resolution better ...than 15μm at the very high luminosity conditions of this experiment. In the first half of 2018 four final production modules have been deployed in the commissioning run of the detector and their performance is discussed.
•Four final type Belle II pixel detector modules operated during Belle II phase 2.•Continuous adjustments of field effect transistor gate voltages due to radiation.•Stable performance with hit efficiencies ¿ 97%.
We present a measurement of the branching fraction and the longitudinal polarization fraction of B0->p+p- decays, as well as the time-dependent CP violating parameters in decays into longitudinally ...polarized p+p- pairs with Belle's final data set of 772x106 BB pairs, at the Y(4S) resonance, collected at the asymmetric-energy e+e- collider KEKB.
We report the first measurement of the T-odd moments in the decay D0→KS0π+π−π0 from a data sample corresponding to an integrated luminosity of 966 fb−1 collected by the Belle experiment at the KEKB ...asymmetric-energy e+e− collider. From these moments we determine the CP-violation-sensitive asymmetry aCPT-odd=−0.28±1.38(stat.)−0.76+0.23(syst.)×10−3, which is consistent with no CP violation. In addition, we perform aCPT−odd measurements in different regions of the D0→KS0π+π−π0 phase space; these are also consistent with no CP violation.
Observation of ϒ(4S)→η^{'}ϒ(1S) Al Said, S; Asner, D M; Ayad, R ...
Physical review letters,
2018-Aug-10, Letnik:
121, Številka:
6
Journal Article
Recenzirano
Odprti dostop
We report the first observation of the hadronic transition ϒ(4S)→η^{'}ϒ(1S), using 496 fb^{-1} data collected at the ϒ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e^{+}e^{-} ...collider. We reconstruct the η^{'} meson through its decays to ρ^{0}γ and to π^{+}π^{-}η, with η→γγ. We measure B(ϒ(4S)→η^{'}ϒ(1S))=3.43±0.88(stat)±0.21(syst)×10^{-5}, with a significance of 5.7σ.
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