5 NOV 2025
11:00 - 12:00

Abstract:

Collisions of various systems, from high-multiplicity pp to p/d/He+Au, exhibit clear signatures of collectivity. Overall, the hydrodynamic description provides the most comprehensive and quantitative account of the experimental data, successfully capturing many of these collective features across system sizes. However, the observation of such ubiquitous collective phenomena, even in small systems, and the attempts to describe them through hydrodynamic evolution have raised important questions about the applicability and limits of hydrodynamics itself. To address these questions, as well as the issues of hydrodynamization and thermalization in the quark–gluon plasma (QGP), I will introduce ComBolt-ITA. This framework offers a unified approach to describing collectivity in the QGP by coupling the pre-equilibrium dynamics with the hydrodynamic evolution through the solution of a (2+1)-dimensional relativistic Boltzmann equation. By implementing the freeze-out process together with a hadronic afterburner, ComBolt-ITA enables the calculation of flow observables across a wide range of systems — from small (pp) to mesoscopic (O+O) and large (Pb+Pb) collisions.

Indico Link:
https://indico.hep.ipm.ir/e/Tabatabaee1

Meeting Place:
Seminar Room, School of Particles and Accelerators, IPM

Link to Join Virtually:
https://www.skyroom.online/ch/ipm-particles/weekly-seminar

3 NOV 2025
11:00 - 12:00

Abstract:

In this lecture, I will review phenomenological studies by the ATLAS and CMS collaborations at the LHC and by H1 and ZEUS at HERA that inform the extraction of parton distribution functions (PDFs) and the strong coupling constant. I will show how diverse measurements—ranging from inclusive DIS to jet, heavy flavour, vector-boson and top-quark pair production—probe different PDFs and kinematic regions, yielding complementary constraints on PDFs and strong coupling constant. Understanding these impacts enables more robust global fits and next-generation proton PDF sets, which are essential inputs for precision tests of the Standard Model and for searches for physics beyond Standard Model.

Based on:
https://doi.org/10.1140/epjc/s10052-025-14178-x


Meeting Place:
Seminar Room, School of Particles and Accelerators, IPM

Link to Join Virtually:
https://www.skyroom.online/ch/ipm-particles/journal-club

20 OCT 2025
11:00 - 12:00

Abstract:

High performance X-ray detector with ultra-high spatial and temporal resolution are crucial for biomedical imaging. This study reports a dynamic direct-conversion CMOS X-ray detector assembled with screen-printed CsPbBr3, whose mobility-lifetime product is 5.2 × 10−4 cm2 V–1 and X-ray sensitivity is 1.6 × 104 µC Gyair–1 cm–2. Samples larger than 5 cm × 10 cm can be rapidly imaged by scanning this detector at a speed of 300 frames per second along the vertical and horizontal directions. In comparison to traditional indirect-conversion CMOS X-ray detector, this perovskite CMOS detector offers high spatial resolution (5.0 lp mm−1) X-ray radiographic imaging capability at low radiation dose (260 nGy). Moreover, 3D tomographic images of a biological specimen are also successfully reconstructed. These results highlight the perovskite CMOS detector’s potential in high-resolution, large-area, low-dose dynamic biomedical X-ray and CT imaging, as well as in non-destructive X-ray testing and security scanning.

Based on:
https://doi.org/10.1038/s41467-024-45871-2


Meeting Place:
Seminar Room, School of Particles and Accelerators, IPM

Link to Join Virtually:
https://www.skyroom.online/ch/ipm-particles/journal-club

15 OCT 2025
11:00 - 12:00

Abstract:

Plasma undulators exploit the propagation of electromagnetic waves within plasma to generate tunable, short-period, and high-intensity magnetic fields, facilitating compact and efficient synchrotron radiation sources. Elliptical plasma-filled waveguides enable the use of shorter wavelength electromagnetic waves, optimizing performance for advanced applications such as X-ray free electron lasers (XFELs). The implementation of corrugated elliptical waveguide designs establishes a new standard by enhancing radiation efficiency and stability. Compared to conventional magnetic undulators, these plasma-based systems offer reduced size and increased magnetic field strength, although they present challenges related to precise plasma control and complex manufacturing processes.

Indico Link:
https://indico.hep.ipm.ir/e/M.Hadad

Meeting Place:
Seminar Room, School of Particles and Accelerators, IPM

Link to Join Virtually:
https://www.skyroom.online/ch/ipm-particles/weekly-seminar

6 OCT 2025
11:00 - 12:00

Abstract:

In accelerator physics, a thorough understanding of the electromagnetic interactions between a charged particle beam and its surrounding vacuum chamber is crucial for optimizing machine performance, particularly regarding stored beam current and beam stability. As a beam traverses the accelerator, it induces electric and magnetic fields in the surrounding structures, resulting in what are known as wake fields. These fields, which represent the collective response of the environment to the beam’s passage, can significantly influence the beam itself. Wake fields impact both the longitudinal and transverse dynamics of the beam. In the longitudinal plane, they can modify the energy distribution, while in the transverse plane, they may produce momentum kicks that lead to beam deflection or emittance growth. Such effects are closely associated with beam instabilities, which impose fundamental limitations on the intensity and quality of stored beams. The geometry and electromagnetic properties of various accelerator components are critical in shaping the wake fields experienced by the beam. Understanding the origins and consequences of these interactions is essential for controlling beam behavior and ensuring reliable accelerator performance.




Meeting Place:
Seminar Room, School of Particles and Accelerators, IPM

Link to Join Virtually:
https://www.skyroom.online/ch/ipm-particles/journal-club

22 SEP 2025
11:00 - 12:00

Abstract:

The role of soft gluons in inclusive collinear parton densities as well as in Transverse Momentum Dependent (TMD) parton densities is discussed. Applying the Parton-Branching (PB) method, the so-called non-perturbative Sudakov form factor could be identified with the integration range z → 1, which is neglected in collinear parton shower approaches. The importance of soft gluons could be shown by investigating the transverse momentum spectrum of Drell-Yan lepton pairs, leading to a width of the intrinsic-kT distribution which is independent on √s, in contrast to what is observed in parton shower approaches. The reason for this behavior is traced back to the non-perturbative Sudakov form factor. The role of soft gluons for observable hadron spectra is discussed and shown to be negligible.

Based on:
https://link.springer.com/article/10.1140/epjc/s10052-024-13657-x

Meeting Place:
Seminar Room, School of Particles and Accelerators, IPM

Link to Join Virtually:
https://www.skyroom.online/ch/ipm-particles/journal-club

17 SEP 2025
11:00 - 12:00

Abstract:

Over the last 50 years, particle colliders have been among the main scientific instruments used to understand the most fundamental particles and laws of the Universe. With its 27km circumference, the Large Hadron Collider (LHC) is currently the most powerful particle collider in the world. The High Luminosity phase (HL-LHC), will increase the machine’s discovery potential with a programme of research up to 2040. But CERN is already thinking beyond the LHC. The future of high-energy physics in the 21st century hinges on designing and building colliders capable of pushing the energy and intensity frontiers by an order of magnitude beyond the present values. The Future Circular Collider (FCC) study explores different collider options, combined into a single research infrastructure built in a 100km underground tunnel, it can offer a solid and diverse physics programme extending beyond the end of the century. A key recommendation of the 2020 update to the European Strategy for Particle Physics is that Europe, in collaboration with the worldwide particle physics community, should undertake a feasibility study for a next-generation hadron collider. As a result, from 2021 to 2027 the Future Circular Collider (FCC) feasibility study is investigating the technical and financial viability of such a facility at CERN. In this talk, I will focus on the accelerator aspects of the FCC feasibility study and highlight the main findings of the report.

Indico Link:
https://indico.hep.ipm.ir/e/A.Mashal1

Meeting Place:
Seminar Room, School of Particles and Accelerators, IPM

Link to Join Virtually:
https://www.skyroom.online/ch/ipm-particles/weekly-seminar

8 SEP 2025
11:00 - 12:00

Abstract:

Non-evaporable getter (NEG) coatings, particularly TiZrV thin films, have been developed at CERN to improve vacuum performance in conductance-limited accelerator systems. These films can transform the inner walls of vacuum chambers into distributed pumps after activation at relatively low temperatures. This presentation will review the main vacuum properties of TiZrV coatings, including their activation behavior, pumping speed, gas saturation capacity, and long-term stability under repeated venting cycles. Special attention will be given to the influence of morphology, elemental composition, and microstructure on film performance. In addition, the results of tests under synchrotron radiation in real accelerator environments will be discussed.

Based on:
https://cds.cern.ch/record/442323/files/est-1999-007.pdf

Meeting Place:
Seminar Room, School of Particles and Accelerators, IPM

Link to Join Virtually:
https://www.skyroom.online/ch/ipm-particles/journal-club

27 AUG 2025
11:00 - 12:00

Abstract:

We consider the running coupling constant in holographic models supported by Einstein-dilaton-Maxwell action for heavy and light quarks. To obtain the dependence of the running coupling constant α on temperature and chemical potential we impose boundary conditions on the dilaton field that depend on the position of the horizon. We use two types of boundary conditions: a simple boundary condition with the dilaton field vanishing at the horizon and a boundary condition that ensures an agreement with lattice calculations of string tension between quarks at zero chemical potential. The location of the first order phase transitions in the (mu,T)-plane does not depend on the dilaton boundary conditions for light and heavy quarks. At these phase transitions, the function α undergoes jumps depending on temperature and chemical potential. We also show that for the second boundary conditions the running coupling decreases with a temperature increase, and the dependence on temperature and chemical potential both for light and heavy quarks is actually specified in quark-gluon plasma (QGP) phase by functions of one variable, demonstrating in this sense automodel behavior.

Indico Link:
https://indico.hep.ipm.ir/e/A.Hajilo

Meeting Place:
Seminar Room, School of Particles and Accelerators, IPM

Link to Join Virtually:
https://www.skyroom.online/ch/ipm-particles/weekly-seminar

25 AUG 2025
11:00 - 12:00

Abstract:

In modern collider experiments, the quest to explore fundamental interactions between elementary particles has reached unparalleled levels of precision. Signatures from particle physics detectors are low-level objects (such as energy depositions or tracks) encoding the physics of collisions (the final state particles of hard scattering interactions). The complete simulation of them in a detector is a computational and storage-intensive task. To address this computational bottleneck in particle physics, alternative approaches have been developed, introducing additional assumptions and trade off accuracy for speed. The field has seen a surge in interest in surrogate modeling the detector simulation, fueled by the advancements in deep generative models. This talk will focus on using deep generative models as a surrogate for traditional event generators and detector simulators.

Based on:
https://doi.org/10.1016/j.revip.2024.100092

Meeting Place:
Seminar Room, School of Particles and Accelerators, IPM

Link to Join Virtually:
https://www.skyroom.online/ch/ipm-particles/journal-club