We report a measurement of the time-dependent CP asymmetry of B0->D(*)CP h0 decays, where the light neutral hadron h0 is a pi0, eta or omega meson, and the neutral D meson is reconstructed in the CP ...eigenstates K+ K-, K0S pi0 or K0S omega. The measurement is performed combining the final data samples collected at the Y(4S) resonance by the BaBar and Belle experiments at the asymmetric-energy B factories PEP-II at SLAC and KEKB at KEK, respectively. The data samples contain ( 471 +/- 3 ) x 10^6 BB pairs recorded by the BaBar detector and ( 772 +/- 11 ) x 10^6, BB pairs recorded by the Belle detector. We measure the CP asymmetry parameters -eta_f S = +0.66 +/- 0.10 (stat.) +/- 0.06 (syst.) and C = -0.02 +/- 0.07 (stat.) +/- 0.03 (syst.). These results correspond to the first observation of CP violation in B0->D(*)CP h0 decays. The hypothesis of no mixing-induced CP violation is excluded in these decays at the level of 5.4 standard deviations.
We describe searches for B meson decays to the charmless vector-vector final states omega omega and omega phi with 471 x 10^6 B Bbar pairs produced in e+ e- annihilation at sqrt(s) = 10.58 GeV using ...the BABAR detector at the PEP-II collider at the SLAC National Accelerator Laboratory. We measure the branching fraction B(B0 --> omega omega) = (1.2 +- 0.3 +0.3-0.2) x 10^-6, where the first uncertainty is statistical and the second is systematic, corresponding to a significance of 4.4 standard deviations. We also determine the upper limit B(B0 --> omega phi) < 0.7 x 10^-6 at 90% confidence level. These measurements provide the first evidence for the decay B0 --> omega omega, and an improvement of the upper limit for the decay B0 --> omega phi.
We present results of a search for CP violation in B0B0bar mixing with the BABAR detector. We select a sample of B0-->D*-Xl+ nu decays with a partial reconstruction method and use kaon tagging to ...assess the flavor of the other B meson in the event. We determine the CP violating asymmetry ACP = (N(B0B0) - N(B0bar B0bar))/(N(B0B0) + N(B0bar B0bar))=(0.06+-0.17+0.38-0.32)%, corresponding to delta_CP =1 - |q/p| =(0.29+-0.84+1.88 -1.61)*10^-3.
We designed and fabricated a novel monolithic active pixel sensor (MAPS), in STMicrolectronics
0.13
μ
m
CMOS technology, exploiting the triple well option to implement, at the pixel level, a more ...complex signal processor and to increase the size of the charge collecting electrode with respect to previously developed CMOS MAPS. This was possible using the deep n-well, available in triple well technology, as a sensing electrode and placing, in the same physical area, part of the readout electronics. The signal processing chain, implemented in the elementary cell, includes a low noise charge preamplifier, a shaper, a discriminator and a latch.
The first prototype chips have been successfully tested with very encouraging results. In this work we present the performance of the front-end electronics and the response of the sensor to ionizing radiation.
The photon spectrum in the inclusive electromagnetic radiative decays of the $B$ meson, $B \to X_{s} \gamma$ plus $B \to X_{d} \gamma$, is studied using a data sample of $(382.8 \pm 4.2) \times 10^6$ ...$\Upsilon(4S) \to B\overli\ ne{B}$ decays collected by the \babar\ experiment at SLAC. The spectrum is used to extract the branching fraction ${\cal B}(B \to X_{s} \gamma)=(3.21 \pm 0.33)\times 10^{-4}$ for $E_{\gamma}>1.8 \gev$ and the direct CP asymmetry $A_{CP}(B \to X_{s+d} \gamma)=0.057 \pm 0.063$. The effects of detector resolution and Doppler smearing are unfolded to measure the photon energy spectrum in the $B$ meson rest frame.
The superB silicon vertex tracker Rizzo, G.; Avanzini, C.; Batignani, G. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2010, Letnik:
617, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The SuperB asymmetric
e
+
–
e
-
collider has been designed to deliver a luminosity greater than
10
36
cm
-
2
s
-
1
with moderate beam currents. Comparing to current B-Factories, the reduced center of ...mass boost of the SuperB machine requires improved vertex resolution to allow precision measurements sensitive to New Physics. We present the conceptual design of the silicon vertex tracker (SVT) for the SuperB detector with the present status of the R&D on the different options under study for its innermost Layer0.
A 4096-pixel MAPS device with on-chip data sparsification Gabrielli, A.; Batignani, G.; Bettarini, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
06/2009, Letnik:
604, Številka:
1
Journal Article
Recenzirano
A prototype of a mixed-mode ASIC composed of a fast readout architecture that interfaces with a matrix of 4096 Monolithic Active Pixel Sensor (MAPS) was fabricated via STM 130
nm CMOS technology. ...Groups of 4×4 pixels form a macro-pixel (MP). The readout architecture is parallel and could overcome the readout speed limit of big matrices. As the output port can only accept one-hit information at a time, an internal queuing system has been provided to face high hit-rate conditions. The ASIC can work in two different manners as it can be connected to an actual full-custom matrix of MAPS or to a digital matrix emulator composed of standard cells, for testing facilities. For both operating modes a slow-control phase is required to load the chip configuration. Previous versions of similar ASICs were designed and tested. The work is aimed at improving the design of MAPS detectors with an on-chip fast sparsification system, for particle tracking, to match the requirements of future high-energy physics experiments. The readout architecture implemented is data driven extending the flexibility of the system to be also used in first level triggers on tracks in vertex detectors. Preliminary simulations and tests indicate that the readout system can cope with an average hit-rate up to 100
MHz/cm
2 if a master clock of 80
MHz is used, while maintaining an overall efficiency over 99%.
We have investigated the depletion voltage changes, the leakage current increase and the charge collection efficiency of a silicon microstrip detector identical to those used in the inner layers of ...the BaBar silicon vertex tracker (SVT) after heavy non-uniform irradiation. A full SVT module with the front-end electronics connected has been irradiated with a 0.9 GeV electron beam up to a peak fluence of 3.5 /spl times/ 10/sup 14/ e/sup -//cm/sup 2/, well beyond the level causing substrate type inversion. We irradiated one of the two sensors composing the module with a non-uniform profile with /spl sigma/=1.4 mm that simulates the conditions encountered in the BaBar experiment by the modules intersecting the horizontal machine plane. The position dependence of the charge collection properties and the depletion voltage have been investigated in detail using a 1060 nm LED and an innovative measuring technique based only on the digital output of the chip.
In September 2008 the SLIM5 collaboration submitted a low material budget silicon demonstrator to test with 12
GeV/
c protons, at the PS-T9 test-beam at CERN. Two different detectors were placed as ...DUTs inside a high-resolution and fast-readout beam telescope. The first DUT was a high resistivity double sided silicon detector, with short strips (“striplets”) and with reduced thickness, at
45
∘
angle to the detector's edge, readout by the data-driven FSSR2 chip. The other one was a 4k-Pixel Matrix of Deep N Well MAPS, developed in a 130
nm CMOS Technology, providing digital sparsified readout. In the following, I present the striplets and also the beam telescope characteristics, with some details about the frontend readout (based on the FSSR2 chip) and some preliminary results of the data-analysis.
PDF
