The front-end chip of the SuperB SVT detector Giorgi, F.; Comotti, D.; Manghisoni, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2013, Volume:
718
Journal Article
Peer reviewed
Open access
The asymmetric e+e− collider SuperB is designed to deliver a high luminosity, greater than 1036cm−2s−1, with moderate beam currents and a reduced center of mass boost with respect to earlier ...B-Factories. The innermost detector is the Silicon Vertex Tracker which is made of 5 layers of double sided silicon strip sensors plus a layer 0, that can be equipped with short striplets detectors in a first phase of the experiment. In order to achieve an overall track reconstruction efficiency above 98% it is crucial to optimize both analog and digital readout circuits. The readout architecture being developed for the front-end chips will be able to cope with the very high rates expected in the first layer. The digital readout will be optimized to be fully efficient for hit rates up to 2MHz/strip, including large margins on the maximum expected background rates, but can potentially accommodate higher rates with a proper tuning of the buffer depth. The readout is based on a triggered architecture where each of the 128 strip channel is provided with a dedicated digital buffer. Each buffer collects the digitized charge information by means of a 4-bit TOT, storing it in conjunction with the related time stamp. The depth of buffers was dimensioned considering the expected trigger latency and hit rate including suitable safety margins. Every buffer is connected to a highly parallelized circuit handling the trigger logic, rejecting expired data in the buffers and channeling the parallel stream of triggered hits to the common output of the chip. The presented architecture has been modeled by HDL language and investigated with a Monte Carlo hit generator emulating the analog front-end behavior. The simulations showed that even applying the highest stressing conditions, about 2MHz per strip, the efficiency of the digital readout remained above 99.8%.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
An active bias tee suitable for small- and large-signal low-frequency (5 Hz to 400 kHz) characterization of electron devices has been designed and manufactured. Different experimental results, ...carried out on 0.25 μm GaAs and GaN HEMTs, confirm the validity of the proposed bias circuit.
The influence of growth conditions on structural properties is reported for core-shell SiC/SiO
2
nanowires grown on silicon substrates by a chemical vapour deposition (CVD) technique. Scanning ...Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) studies show a correlation between the growth temperature and the nanowire structure and highlight the possibility to control the inner core diameter by varying the precursor concentration. The nanowire covering of the substrate was considerably enhanced and homogenized using drop casting surfactant-aided deposition of catalysts on an H-terminated silicon 100 surface.
By varying the growth conditions in chemical vapour deposition synthesis we demonstrate the possible tuning of the core-shell ratio of SiC/SiO
2
nanowires.
Acute graft-versus-host disease (aGVHD) has been classified according to the Seattle criteria as grades 0,1, II, III, and IV for 20 years. The predictive value of such detailed grading is a matter of ...debate; publications usually report GVHO as present or absent or as absent, moderate, or severe. The Working Party Chronic Leukemia of the European Group for Bone Marrow Transplantation analyzed data of 1,294 patients transplanted from an allogeneic donor for chronic myelogenous leukemia (CML) in first chronic phase and tested the predictive value of aGVHD grading for the following endpoints: day 100 mortality (D100M), transplant-related mortality (TRM), relapse incidence (RI), leukemia-free survival (LFS), and survival (SURV). aGVHD was absent in 462 patients (35.7%), grade I occurred in 335 (25.8%), grade II in 264 (20.5%), grade III in 110 (8.5%), and grade IV in 123 patients (9.5%). A total of 297 patients (23%) died within 100 days, 495 patients (38%) died of any TRM, and 100 patients (8%) died of relapse. D100M according to grades 0, I, II, III, and IV was 17%, 13%, 19%, 38%, and 70%, respectively, with significant difference between 0-II versus lll-IV. TRM was 28%, 27%, 43%, 68%, and 92%, respectively, with a distinct separation between 0-I versus ll-IV. RI showed a continuous decrease of 37%, 30%, 23%, 18%, and 8%, respectively, with increasing aGVHD. LFS was 45%, 51%, 44%, 26%, and 7%, respectively, and was best for patients with grade I aGVHD. This finding was also reflected in a better overall survival (60%, 64%, 53%. 30%, and 8%, respectively). The better LFS for grade I aGVHD patients compared with patients with grade 0 or II aGVHD was confirmed (P = .05) in a multivariate analysis. These data document the value of the present 5-point grading of aGVHD, ie, different outcome is observed depending on endpoint analyzed. Restricting information about aGVHD to presence or absence is not warranted.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
To evaluate the performance of an optical CT scanner for scanning dosimetric gels, it is useful to have a gel phantom in which the 3-dimensional shapes and extinction (attenuation) coefficients of ...the internal features can be manufactured at will. We describe and evaluate an improved version of the Oldham phantom, employing scattering gels.
Summary
Females with the monoclonal type of essential thrombocythaemia (ET), based on the X‐chromosome inactivation pattern (XCIP), have previously been shown to present a higher incidence of ...thrombosis than polyclonal ones. We aimed to assess correlations between XCIP, thrombosis, and three epigenetic markers of ET, namely PRV‐1 overexpression, endogenous erythroid colony (EEC) formation, and reduced platelet Mpl content. Fifty‐three (60%) of 88 subjects studied had monoclonal myelopoiesis and presented a 32% incidence of major thrombosis compared with 6% of polyclonal subjects (P = 0·009). The frequency of abnormalities of PRV‐1, EEC, or Mpl was similar in monoclonal and polyclonal subjects (respectively, 28%, 48%, 75%, and 37%, 27%, 63%), and none of them correlated with thrombosis. We conclude that the exploited epigenetic markers constitute independent phenotypic variations and are not clustered according to monoclonality of myelopoiesis in ET; none of them could serve as a surrogate marker of thrombotic risk in male subjects with ET.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Thirty-eight second allogeneic bone marrow transplants (BMT) for acute leukemia relapsed after first BMT were performed in 13 Italian centers between 1987 and 1994. Twenty-one patients had acute ...myelogenous leukemia (AML), 17 acute lymphoblastic leukemia (ALL); at second BMT 24 patients were in complete remission (CR) and 14 in relapse. The median time to relapse after first BMT was 10 months (range 1-70). Grade II or greater acute graft-versus-host disease (GVHD) after second transplant occurred in 34.2% of patients and a chronic GVHD in 31.5% of patients. Twenty-four patients died: seven from early transplant-related mortality (TRM), 13 from relapse and four from late toxicity. As of 31 July 1996, at a median follow-up of 47 months (range 22-85), there are 14 survivors. The three-year probability of TRM, relapse and event-free survival (EFS) is 28%, 40% and 42% respectively. In 20 of 27 evaluable patients, remission duration after second BMT was longer than after the first BMT. A diagnosis of AML was correlated with a better outcome. These data support the usefulness of second allograft in selected patients with AML relapsing after a first BMT.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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