Kirika Uchida

We instigate the angle-dependent magnetoresistance (AMR) of the layered nodal-line Dirac semimetal ZrSiS for the in-plane and out-of-plane current directions. This material has recently revealed an intriguing butterfly-shaped in-plane AMR whose origin is not well understood. Our aim was to understand the mechanism behind this peculiar shape of AMR and also to probe AMR in the out-of-plane current direction. In contrast to the in-plane AMR, the polar out-of-plane AMR shows a surprisingly different response with a pronounced cusplike feature. The maximum of the cusplike anisotropy is reached when the magnetic field is oriented in the $a\text{\ensuremath{-}}b$ plane. Moreover, the AMR for the azimuthal out-of-plane current direction exhibits a very strong fourfold $a\text{\ensuremath{-}}b$ plane anisotropy. Combining the Fermi surfaces calculated from first principles with the Boltzmann's semiclassical transport theory, we reproduce all the prominent features of the unusual behavior of the in-plane and out-of-plane AMR. We can conclude that the dominant contribution the cusplike AMR lies in open orbits of the hole pocket and, in general, AMR is strongly influenced by charge compensation effect and the off-diagonal conductivity tensor elements, which give rise to peculiar butterfly-shaped AMR. Finally, the semiclassical model was also able to clarify the origin of strong nonsaturating (subquadratic) transverse magnetoresistance observed in this material, as an effect of imperfect charge-carrier compensation and open orbits.

The CBC3.1 is the final version of the CMS Binary Chip for readout of the outer radial region of the upgraded CMS Tracker at the High-Luminosity LHC. The CBC development was completed with an engineering run in 2018 and two pre-production lots delivered in 2019. Large scale manufacture began in May 2021. Issues were raised when some wafers were tested at low temperature (−30 ∘C) and probing was suspended for investigation. After studies, some additional tests were added to reject affected chips and we show that the impact of the low temperature issues is expected to be very small.

A tool kit for object-oriented network-distributed online-environment (KONOE), a toolkit for data-acquisition software that is based on object-oriented methodology and network-distributed architecture, has been developed. KONOE provides a framework for distributed data-acquisition (DAQ) systems. A distributed DAQ has good scalability because the DAQ user can add inexpensive and high-performance PCs to the system. We have developed a network-distributed DAQ for the KEK PS-T473 Experiment by using the KONOE toolkit, and it is confirmed to have sufficiently good performance to satisfy the requirements from the experiment.

The differential cross section of the process gamma gamma -> pi^0 pi^0 has been measured in the kinematical range 0.6 GeV < W < 4.0 GeV and |cos theta*|<0.8 in energy and pion scattering angle, respectively, in the gamma gamma center-of-mass system. We find at least four resonant structures including a peak from f_0(980). In addition, there is evidence for chi_{c0} production. We also make a preliminary discussion of the angular dependence and cross section ratio to gamma gamma -> pi^+ pi^-.

Algorithms for b-tagging are calibrated with t t events for the first time with early data in the ATLAS experiment.Compared to di-jet events that have been used for b-tagging calibrations, t t events provide more similar topology to most of the important signals in the experiment.The higher multiplicity of jets, higher jet p T , and high purity of the t t event sample make it an attractive calibration sample.The high t t production rate in the LHC enables an initial calibration with 35 pb -1 .Two methods and their results are presented.

A new tracking detector is under development for use by the CMS experiment at the High-Luminosity LHC (HL-LHC).A crucial component of this upgrade will be the ability to reconstruct within a few microseconds all charged particle tracks with transverse momentum above 3 GeV, so they can be used in the Level-1 trigger decision.A concept for an FPGA-based track finder using a fully time-multiplexed architecture is presented, where track candidates are reconstructed using a projective binning algorithm based on the Hough Transform followed by a track fitting based on the linear regression technique.A hardware demonstrator using MP7 processing boards has been assembled to prove the entire system, from the output of the tracker readout boards to the reconstruction of tracks with fitted helix parameters.It successfully operates on one eighth of the tracker solid angle at a time, processing events taken at 40 MHz, each with up to 200 superimposed proton-proton interactions, whilst satisfying latency constraints.The demonstrated track-reconstruction system, the chosen architecture, the achievements to date and future options for such a system will be discussed.

KONOE, a toolkit which is based on Object-Oriented scheme and Network-Distribute architecture, has been developed. It includes many C++ based classes to support DAQ developers. They will be able easily and quickly to develop their distributed DAQ by using this utility. We have developed a network-distributed KONOE DAQ for KEK PS-T473 experiment and tested DAQ performance.

Proposes a new model of nested transactions which achieves higher concurrency of transactions than the traditional model. Most of the previously proposed concurrency control algorithms for nested transactions were based on two-phase locking (2PL). In such algorithms, however, the concurrency of transactions is not so high. To achieve high concurrency, it was decided to apply serialization graph testing (SGT) to the concurrency control of nested transactions. However, in the traditional nested transactions model, the subtransactions don't satisfy the ACID (atomicity, consistency, isolation and durability) properties. We designed our nested transaction model so that each subtransaction satisfies the ACID properties. We considered applying an SGT scheduling algorithm to our model. By scheduling subtransactions as independent transactions, high concurrency can be achieved. However, the usual SGT algorithm causes deadlocks in our model. To avoid these deadlocks, we modified the usual SGT algorithm.