The DMAPS upgrade of the Belle II vertex detector Babeluk, M.; Barbero, M.; Baudot, J. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2024, Letnik:
1064
Journal Article
Recenzirano
The Belle II experiment at KEK in Japan considers an upgrade for the vertex detector system in line with the accelerator upgrade for higher luminosity at long shutdown 2 planned for 2028.
One ...proposal for the upgrade of the vertex detector called VTX aims to improve background robustness and reduce occupancy using small and fast pixels. VTX accommodates the OBELIX depleted monolithic active CMOS pixel sensor (DMAPS) on all five proposed layers. OBELIX is specifically developed for the VTX application and based on the TJ-Monopix2 chip initially developed to meet the requirements of the outer layers of the ATLAS inner tracker (ITk).
This paper will review recent tests of the TJ-Monopix2 chip as well as various design aspects of the OBELIX-1 chip currently under development.
Ti-doped NaAlH4 can be prepared in a simple way by hydrogenation of aluminum powder in conjunction with sodium hydride in the presence of Ti(OBu)4 (Bu= n-C4Hg) as a dopant. After a few ...hydrogenation/dehydrogenation cycles the material reaches a storage capacity of ~4 wt%H2 and exhibits reaction rates comparable to or exceeding those previously found for NaAlH4 doped with Ti(OBu)4 in organic solvents Bogdanovic et al.: J. Alloys Compd. 302, 36 (2000).
New reversible hydrogen storage systems are proposed, based on catalyzed reactions (Eqs. 4–6). The catalytic acceleration of the reactions in both directions is achieved by doping alkali metal ...aluminium hydrides with a few mol% of selected Ti compounds. The PCI diagrams of the Ti catalyzed systems show an absence of hysteresis and nearly horizontal pressure plateaus. The PCI of the NaAlH
4 system reveals two temperature-dependent pressure plateaus, corresponding to the two-step reversible dissociation of NaAlH
4. The PCI of the Na
3AlH
6 system shows only one pressure plateau; the latter can be lowered by partial substitution of Na by Li. In cyclic tests, reversible H
2 capacities of 4.2–3.1 and 2.7–2.1 wt% H have been achieved.
High throughput experimentation methods are well established in many companies and in research groups in academia. Recent advances were primarily achieved in the fields of innovative synthesis ...methods for bulk catalysts, using amongst other techniques split-and-pool methods, in miniaturization of reactors while increasing parallelization up to 625-fold on an approximately 7
cm
×
7
cm footprint, and in development of novel software for “intelligent” design of libraries. Developments in these fields will be highlighted with a focus on applications in oxidation catalysis.
CMOS MAPS upgrade for the Belle II Vertex Detector Babeluk, M.; Barbero, M.; Baudot, J. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
03/2023, Letnik:
1048
Journal Article
Recenzirano
Odprti dostop
The success of the Belle II experiment in Japan relies on the very high instantaneous luminosity, close to 6×1035 cm−2 s−1, expected from the SuperKEKB collider. The corresponding beam conditions at ...such luminosity levels generate large rates of background particles and creates stringent constraints on the vertex detector, adding to the physics requirements. Current prospects for the occupancy rates in the present vertex detector (VXD) at full luminosity fall close to the acceptable limits and bear large uncertainties. In this context, the Belle II collaboration is considering the possibility to install an upgraded VXD system around 2027 to provide a sufficient safety margin with respect to the expected background rate and possibly enhance tracking and vertexing performance.
The VTX collaboration has started the design of a fully pixelated VXD, called VTX, based on fast and highly granular Depleted Monolithic Active Pixel Sensors (DMAPS) integrated on light support structures.
The two main technical features of the VTX proposal are the usage of a single sensor type over all the layers of the system and the overall material budget below 2% of radiation length, compared to the current VXD which has two different sensor technologies and about 3% of radiation length. A dedicated sensor (OBELIX), taylored to the specific needs of Belle II, is under development, evolving from the existing TJ-Monopix2 sensor. The time-stamping precision below 100 ns will allow all VTX layers to take part in the track finding strategy contrary to the current situation. The first two detection layers are designed according to a self-supported all-silicon ladder concept, where 4 contiguous sensors are diced out of a wafer, thinned and interconnected with post-processed redistribution layers. The outermost detection layers follow a more conventional approach with a cold plate and carbon fibre support structure, and light flex cables interconnecting the sensors.
This document will review the context, technical details and development status of the proposed Belle II VTX.
Thermodynamics and kinetics of the reversible dissociation of metal-doped NaAlH
4 as a hydrogen (or heat) storage system have been investigated in some detail. The experimentally determined ...enthalpies for the first (3.7 wt% of H) and the second dissociation step of Ti-doped NaAlH
4 (3.0 wt% H) of 37 and 47 kJ/mol are in accordance with low and medium temperature reversible metal hydride systems, respectively. Through variation of NaAlH
4 particle sizes, catalysts (dopants) and doping procedures, kinetics as well as the cyclization stability within cycle tests have been substantially improved with respect to the previous status B. Bogdanović, M. Schwickardi, J. Alloys Comp. 253–254 (1997) 1. In particular, using combinations of Ti and Fe compounds as dopants, a cooperative (synergistic) catalytic effect of the metals Ti and Fe in enhancing rates of both de- and rehydrogenation of Ti/Fe-doped NaAlH
4 within cycle tests, reaching a constant storage capacity of ∼4 wt% H
2, has been demonstrated. By means of
57Fe Mössbauer spectroscopy of the Ti/Fe-doped NaAlH
4 before and throughout a cycle test, it has been ascertained that (1) during the doping procedure, nanosize metallic Fe particles are formed from the doping agent Fe(OEt)
2 and (2) already after the first dehydrogenation, the nanosize Fe particles with NaAlH
4 present are probably transformed into an Fe–Al-alloy which throughout the cycle test remains practically unchanged.
In this paper, we describe the development of two parallel real time detection systems for the analysis of the products of a heterogeneously catalyzed gas phase reaction based on the photoacoustic ...effect. We developed a process addressing the problem of automated catalyst preparation and prepared bulk metal oxides with high surface areas by an automated, parallelized synthesis based on activated carbon. To evaluate analytical systems and catalytic activity of our materials we performed catalytical tests in CO oxidation and ODH of ethane.
The “inorganic Grignard reagents”, in particular those of 1, have surprisingly been shown to be efficient homogeneous catalysts for the conversion of inactive chloroarenes and heteroarenes (via the ...aryl–iron intermediate 2) into the corresponding Grignard compounds. The aryl–Grignard compounds are starting materials for, among other things, the preparation of aryl boron acid esters, which serve as substrates for the technically important Suzuki coupling.
