A time resolved study of injection backgrounds during the first commissioning phase of SuperKEKB

We report on measurements of beam backgrounds during the first commissioning phase of the SuperKEKB collider in 2016, performed with the plastic scintillator and silicon photomultiplier-based CLAWS detector system. The sub-nanosecond time resolution and single particle detection capability of the sensors allow bunch-by-bunch measurements, enable CLAWS to perform a novel time resolved analysis of beam backgrounds, and make the system uniquely suited for the study of injection backgrounds. We present measurements of various aspects of regular beam background and injection backgrounds which include time structure and decay behavior of injection backgrounds, hit-energy spectra and overall background rates. These measurements show that the elevated background rates following an injection generally last for several milliseconds, with the majority of the background particles typically observed within the first 500 us. The injection backgrounds exhibit pronounced patterns in time, connected to betatron and synchrotron oscillations in the accelerator rings. The frequencies of these patterns are determined from detector data.Comment: 19 pages, 12 figures, published in EPJ

Molecular analysis of the BCR-ABL1 kinase domain in chronic-phase chronic myelogenous leukemia treated with tyrosine kinase inhibitors in practice: Study by the Nagasaki CML Study Group

An appropriate trigger for BCR-ABL1 mutation analysis has not yet been established in unselected cohorts of chronic-phase chronic myelogenous leukemia patients. We examined 92 patients after 12 months of tyrosine kinase inhibitor (TKI) treatment in Nagasaki Prefecture, Japan. Univariate analysis revealed that significant factors associated with not attaining a major molecular response (MMR) were the presence of the minor BCR-ABL1 fusion gene, a low daily dose of TKI, and the emergence of BCR-ABL1 kinase domain mutations conferring resistance to imatinib. Factors associated with the loss of sustained MMR were a low daily dose of TKI and the emergence of alternatively spliced BCR-ABL1 mRNA with a 35-nucleotide insertion. Taken together, our results suggest that the search for BCR-ABL1 mutations should be initiated if patients have not achieved MMR following 12 months of TKI treatment

Measurement of {alpha}{sub s} from hadronic event observables at the Z{sup 0} resonance

The authors have measured the strong coupling {alpha}{sub s} using hadronic decays of Z{sup 0} bosons collected by the SLD experiment at SLAC. The data were compared with QCD predictions both at fixed order, O({alpha}{sub s}{sup 2}), and including resummed analytic formulae based on the leading and next-to-leading logarithm approximation. The study includes event shapes, jet rates, and particle correlations. They checked the consistency between {alpha}{sub s} extracted from these different measures and found the dominant uncertainty on {alpha}{sub s} to be from uncalculated higher order contributions

Measurement and correction of on- and off-momentum beta functions at KEKB

Optics correction is an important issue in the KEKB B-factory. Especially, the correction of beta functions is performed so as to reach near half-integer resonance of the horizontal betatron tune as closely as possible. Consequently, the luminosity can be improved during experiments of the B-meson in e^{+}e^{-} collisions. Therefore, we have developed a correction method of the beta function not only at the designed beam energy, but also at an energy deviated from the nominal value. We present the procedures used to measure the behavior of the beta function, which depends on the momentum deviation, and the results compared with the model optics in the KEKB rings

Simulations and experimental results of beam-beam effects in SuperKEKB

The beam-beam interaction is one of the most critical factors determining the luminosity performance of colliders. As a circular collider utilizing the crab-waist scheme, multiple factors, such as beam-beam, crab waist, impedances, etc., interact to determine the luminosity of SuperKEKB. The interplay of these factors makes it challenging to predict luminosity via simulations. This paper presents recent advances in understanding the luminosity performance of SuperKEKB from beam-beam simulations and experiments. The key aspects affecting the luminosity of SuperKEKB, as well as the areas where further research is needed, are highlighted

Benchmarking of Simulations of Coherent Beam-beam Instability with SuperKERKB Measurement

Coherent beam-beam instability in head-tail mode has been predicted in collision with a large crossing angle. The instability is serious for design of future e⁺e⁻ colliders based on the large crossing angle collision. It is possible to observe the instability in SuperKEKB commissioning. Horizontal beam size blow-up of both beams has been seen depending on the tune operating point. We report the measurement results of the instability in SuperKEKB phase II commissioning