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Incoherent horizontal emittance growth due to the interplay of beam-beam interaction and longitudinal wakefield in crab-waist colliders
No full textIn this paper, we investigate incoherent quadrupolar synchrobetatron resonances caused by beam-beam collisions and their interplay with longitudinal wakefields in the context of crab-waist colliders. We present a comprehensive theoretical review of the established theory of synchrobetatron resonances and extend the formalism to explore horizontal synchrobetatron resonances specific to crab-waist colliders. As a case study, we examine incoherent horizontal emittance growth at the SuperKEKB and demonstrate through simulations that the interplay between beam-beam and longitudinal wakefields leads to a horizontal blowup of the bunch size and that the study of the dynamics can be reduced to the horizontal-longitudinal plane, independent of the motion in the vertical dimension. We present extensive simulation results using the codes bbws, pyheadtail, and xsuite, connect our analytical findings with these findings, and propose strategies to mitigate horizontal blowup.In this paper, we investigate quadrupolar sychrobetatron resonances caused by beam-beam collisions and their interplay with longitudinal wakefields in the context of crab-waist colliders. We present a comprehensive theoretical review of the established theory of sychrobetatron resonances and extend the formalism to explore horizontal sychrobetatron resonances specific to crab-waist colliders. As a case study, we examine incoherent horizontal emittance growth at the SuperKEKB and demonstrate through simulations that the interplay between beam-beam and longitudinal wakefields leads to a horizontal blowup of the bunch size and that the study of the dynamics can be reduced to the horizontal-longitudinal plane, independent of the motion in the vertical dimension. We present extensive simulation results using the codes BBWS, PyHEADTAIL and Xsuite, connect our analytical findings with these findings, and propose strategies to mitigate horizontal blowup
Radiation effects of CERN-PS 24 GeV/c protons in silicon strip sensors, evaluated with ATLAS18 ITk strip sensor test structures
No full textMiniature strip detectors developed for ATLAS ITk were irradiated with 24 GeV/c protons. Samples were positioned at various angles with respect to the proton beam. Blocks of G10 material were placed in front of detectors to study the effect of scattering of primary protons on fluence received by samples. Results confirm that both angle and scattering have a significant effect on the actual fluence to which samples are exposed. Miniature detectors irradiated with protons were also irradiated with reactor neutrons so that the combination of equivalent fluences from protons and neutrons matched the combination expected in the most exposed part in ITk strip detector. Good charge collection was measured confirming that strip detectors in ATLAS ITk are sufficiently radiation hard for successful operation up to highest fluences expected at HL-LHC
The ambiguous nature of cosmic ray PeVatrons
No full textUnderstanding which are the Galactic sources responsible for the production of the highest energy cosmic rays is one of the main task of the High Energy Astrophysics. This long standing problem has recently received new lymph thanks to the results obtained from ground-based high energy gamma-ray detectors like HAWC and LHAASO. Those experiments have shown that the Galaxy is full of PeVatrons, namely sources able to produce particles up the impressive energy of Peta electronvolts. Probably the most impressive result is that, contrary to past expectations, different type of sources seem to work as PeVatrons, like pulsar wind nebulae, supernova remnants, stellar clusters and micro quasars. However, at the moment, it is unclear if the knee region of the CR spectrum is dominated by a single type of sources or is rather the convolution of several different classes. Moreover, the pour angular resolution of the mentioned detectors often prevent one to precisely identify the source nature. In this talk I will review the present status of the field.</p
Visit by UNCTAD Secretary-General Rebeca Grynspan
No full textVisit by Ms Rebeca Grynspan, Secretary-General United Nations Trade and Developmen
CERN PGDay 2025
No full textWelcome from the organizing team, logistics info and notices, sponsors presentation and special thank
Heavy flavour results from ATLAS
No full textSlides for invited talk at Epiphany 2025 conference, Cracow, Poland, Jan. 13-17, 2025
Data Placement Optimization for ATLAS in a Multi-Tiered Storage System within a Data Center
No full textScientific experiments and computations, especially in High Energy Physics, are generating and accumulating data at an unprecedented rate. Effectively managing this vast volume of data while ensuring efficient data analysis poses a significant challenge for data centers, which must integrate various storage technologies. This paper proposes addressing this challenge by designing and developing a precise data popularity prediction model utilizing state-of-the-art AI/ML techniques. This model is crafted from the analysis of ATLAS data and access patterns. It enables us to migrate infrequently accessed data to more economical storage media, such as tape drives, while storing frequently accessed data on faster yet costlier storage media like HDD or SSD. This strategic approach ensures data is placed optimally into the appropriate storage classes, thereby maximizing storage capacity while minimizing data access latency for end-users. Furthermore, the paper includes a performance evaluation of the prediction model using various key metrics such as F1 score, accuracy, precision and recall. Finally, we present a prototype use case, leveraging real-world file access data to assess the model’s impact on performance