9. miniworkshop difrakce, korelací a ultraperiferních srážek

8 Sept 2026, 16:00 → 10 Sept 2026, 20:00 Europe/Prague

ČVUT Děčín

The workshop addresses topics in phenomenology, instrumentation, and data analysis techniques used in photo-nuclear interaction, in relativistic heavy-ion collisions, and in physics beyond the Standard Model. It will have a colloquial character with emphasis on discussing various tools and approaches used in the field. The majority of talks will be covered by students.

Tuesday 8 September

16:00 → 17:00 Registration in the hotel

17:00 → 17:10 Welcome and news

Speakers: Marek Matas (České vysoké učení technické v Praze), Roman Lavička (CTU FNSPE)

ducd26_welcome.pdf

17:10 → 18:30 Special Topics

Convener: Alexian Marc Lejeune (Czech Technical University)

17:10 Development of a Tabletop Experiment for Rare-Event Searches Using 139Ce Isotope-Doped CeBr3 Scintillator

I will present my previous work on the development of a tabletop experiment for rare-event searches using a $^{139}\mathrm{Ce}$ isotope-doped CeBr$_3$ scintillator. The experiment is based on the Source-as-Detector concept, where the radioactive isotope is incorporated directly into the scintillation crystal. I will introduce the detector fabrication, scintillation performance, integration with a $4\pi$ BGO veto system, and low-background measurements at Yemilab. In the first measurement campaign, about $9.6\times10^{9}$ events were collected to search for the missing 165.86\,keV M1 gamma transition in $^{139}\mathrm{Ce}$ electron-capture decay. I will also discuss the potential of this compact setup for probing extremely rare nuclear transitions and possible axion-like particle signatures.

Speaker: Nguyen Thanh Luan

Decin_Luan_CeBr3.pdf

17:30 Chromatic calorimeter

Chromatic calorimetry is a new concept for electromagnetic calorimetry that utilizes segmented scintillators (which emmit different wavelength) and spectrally selective readout to perform longitudinal recosntructin  of the electromagnetic shower inside the calorimeter. 
In this talk the results of the proof-of-concept of the chromatic calorimeter (CCAL) prototype will be shown. The prototype is assembled with commercial materials and was tested under high-energy beams at the CERN SPS facility.

Speaker: Solangel Rojas Torres

CCAL.pdf

17:50 The structure of scientific revolutions

the evolution of science according to the book "The structure of
scientific revolutions" is presented in a very schematic form and
discuss within the framework of thinking about potential direction
to search for Beyond the Standard Model paradigms.
The presentation is organised in an interactive format to encourage
the participation of the public and hear their own experiences and
thoughts about the practice of science.

Speaker: Guillermo Contreras (FJFI)

Kuhn.pdf

19:00 → 21:00 Dinner

Wednesday 9 September

08:30 → 09:30 Breakfast

10:00 → 11:10 Dark Matter

Convener: Sára Haidlová

10:00 Intro to group plans/goals/ ...

Speaker: Marek Matas (České vysoké učení technické v Praze)

Group news and updated on direct detection.pdf

10:10 Update on the direct detection of dark matter

Direct detection of dark matter has advanced a lot in the past two years. In this talk, we will go over these advances and look into the up to date reports that were given by some of the leading experiments in the field. Xenon experiments are advancing into the neutrino fog, silicon targets are suppressing backgrounds and scaling up in mass and new sub-eV threshold devices join the hunt.

Speaker: Marek Matas (České vysoké učení technické v Praze)

10:30 Chiral phonons in topological materials for the dark matter detection

The aim of my bachelor’s thesis was to investigate the potential of Pb(1-x)Sn(x)Te to form a detector of low-energy dark matter interactions based on the detection of the magnetic moments of chiral phonons. The main DFT and DFPT calculations were performed using the ABINIT software, supplemented by a post-processing program for calculating the angular and magnetic moments of chiral phonons.
This talk will summarize the results and discuss the future steps needed to take to find a desirable material suited for the chiral-phonon-based dark matter detector.

Speaker: Barbora Růžičková

chiral_phonons.pdf

chiral_phonons.pptx

10:50 Asymmetric quantum dots as directional dark matter detectors

Quantum dots are semiconductor-like nanoscale crystals whose bandgap energy is primarily determined by physical size, making them highly promising tunable probes for sub-GeV dark matter direct detection.
Importantly, asymmetric quantum dots possess unequal spatial dimensions along different crystal axes, resulting in directionally dependent momentum distribution.
A dark matter particle moving parallel to the elongated axis experiences a fundamentally different electronic structure of the target material than one approaching along the shorter axis.
Such a distinction enables the detection of a directionally dependent signal, allowing background suppression impossible in most conventional detectors.
This talk will cover a brief theoretical introduction along with my present computational results of daily modulation and angle-dependent dark matter scattering rates for two studied elongated systems.

Speaker: Václav Výborný

vyborny_DUCD26.pdf

11:10 → 12:00 QCD

Convener: Nguyen Thanh Luan

11:10 Shadowing in the LTA approximation

Shadowing is the experimental observation that inclusive deep
inelastic cross section off protons scaled by the mass number A do
not correspond to equivalent cross section off a nucleus A.
One of the most popular models attempting to describe this
phenomenon is the leading-twist approximation (LTA). The
implementation of LTA in a model based on multiple nucleon
scattering, and a fluctuation incoming photon is discussed in
detail. The final form of the coherent cross section is derived
making clear what is the physics origin of each term, and the
approximations involed in the modeling of this process.

Speaker: Guillermo Contreras (FJFI)

NotesLTA.pdf

12:00 → 14:00 Lunch

14:00 → 16:00 Instrumentation

Convener: Daniel Battistini (Czech Technical University in Prague)

14:00 MFT QC

The Muon Forward Tracker (MFT) is a silicon pixel detector operating since Run 3 as one of the subdetectors of ALICE. This talk covers the Quality Control system developed to monitor the detector and its data in real time, covering several stages of the data processing chain. The QC framework, including automated checks and post-processing tools, is used to identify potential issues during data taking and assess the quality of the recorded data. The talk will also briefly discuss ongoing developments and plans for Run 4.

Speakers: Jakub Juračka (FNSPE CTU), Sára Haidlová

MFTQC.pdf

14:20 MFT AQC

This contribution aims at presenting the Muon Forward Tracker (MFT) data asynchronous quality control (AQC) framework during Run 3 of the LHC which ended in June 2026.
The AQC strategy and its evolution over the years will be summarized as well as the different tools that were developed to improve its efficiency.

Speaker: Alexian Marc Lejeune (Czech Technical University)

MFT_AQC_Decin2026.pdf

14:40 MuonID for ALICE3

ALICE 3 is a new detector proposed to operate during the LHC Run 5 and 6. The Muon IDentifier (MID) detector is one of the ALICE 3 subsystems; it is optimized to detect muons down to momenta below 1.5 GeV/c for rapidities |y|<1.3. These muons will be used for the reconstruction of J/ψ vector mesons down to zero transverse momentum at midrapidity. The ALICE 3 tracker large-acceptance will offer access to rare charmonium and exotic states that decay to Jpsi, pions and photons.
The MID detector will be installed outside the superconducting magnet and includes a magnetic steel absorber with variable thickness (70 cm to 38 cm). Given that the particle flux will be of the order of a few Hz/cm^2, plastic scintillator, multi-wire proportional chambers (MWPC), and resistive proportional chambers (RPC) technologies are being considered for the construction of MID.
This talk presents an overview of the detector and its physics goals. Emphasis is made on recent results from a beam test, the status, and the plans for the R&D of the MID detector.

Speaker: Solangel Rojas Torres

MID_update.pdf

15:00 Single-photon calibration for fine-mesh PMT

Photomultiplier tubes (PMTs) are high-precision light detector modules with myriad uses in high-energy physics experiments. Fine-mesh photomultiplier tubes are a subclass of PMTs that use mesh layers in place of conventional dynode structures; their key advantage is resilience in high-magnetic-field environments. However, they are prone to producing under-amplified signals, which can cause considerable inaccuracy when analyzing their charge output spectra for calibration. The goal of our study is to test alternative methods for calibration of fine-mesh PMTs, in particular a “model-independent” method derived from statistical principles, proposed by Guardincerri et al. in a 2017 paper on the subject. This presentation is a progress report of this study, detailing the calibration problem, potential solutions, test bench setup, and methods used for data handling.

Speaker: Alexander Paul Bullock

Decin2026.pptx

15:20 Investigation of the Radiation Hardness of Plastic Materials for High-Energy Physics Detectors

I will present my current work on the radiation hardness of plastic materials for high-energy physics detectors. Several candidate materials relevant to detector R\&D for ALICE were irradiated with a high-energy proton beam at the CERN PS-IRRAD facility. The study focuses on radiation-induced changes in their optical and scintillation performance and on how the response varies among materials with different compositions and fabrication routes. I will discuss the observed degradation behavior, the comparison between the investigated materials, and the implications for their use in future detector systems operating in high-radiation environments.

Speaker: Nguyen Thanh Luan

Decin_Luan_RH_ver2.pdf

16:00 → 16:30 Coffee break

16:30 → 18:30 ALICE

Convener: Roman Lavička (CTU FNSPE)

16:30 Asymmetries in coherent rho production

This talk presents a study of azimuthal asymmetries in coherent $\rho^0$ photoproduction in Pb--Pb ultraperipheral collisions at $\sqrt{s_{\mathrm{NN}}}=5.36$ TeV. The analysis investigates modulations in the $\Delta\phi$ spectrum to probe quantum interference effects at femtometre scales, including contributions beyond the expected $\cos(2\Delta\phi)$ modulation. The talk will discuss the analysis strategy and the extraction of the modulation amplitudes, highlighting the observation of odd-order contributions and their possible connection to Coulomb--nuclear interference.

Speaker: Jakub Juračka (FNSPE CTU)

DCUCD_JJ.pdf

16:50 Asymmetries in coherent jpsi production

This talk presents results on studies of azimuthal anisotropy in coherent J/psi. Analysed data were taken in 2023 during PbPb period on the ALICE experiment. Analysis overview includes event and track selection cuts, analysis strategy and first results. The results include a set of corrections that are necessary to apply due to inevitable detector effects and contamination of the analysed sample by other processes. First results show dependence of the asymmetry on the impact parameter of the collision and, furthermore, the transverse momentum dependence.

Speaker: Sára Haidlová

DUCD26_SH.pdf

17:10 Flow of heavy-flavour hadrons

Collectivity in small systems can be summarized by a simple question : how can a collision that produces on average only a dozen of particles be described so well by hydrodynamics?
In this contribution we aim to measure the pseudorapidity dependence of the elliptic flow coefficient v2 to constrain hydrodynamical models even more.
This measurement is done thanks to the ALICE experiment new forward detector additions, the Fast Interaction Trigger (FIT) and the Muon Forward Tracker (MFT) in light ion collisions collected in July 2025.

Speaker: Alexian Marc Lejeune (Czech Technical University)

AlexianLejeune_Decin2026.pdf

17:30 On the particle emission for hadrons in high energy collisions at the LHC

The measurement of hadronic interactions via the femtoscopy method often requires constraints to the particle-emitting source, which describes the inter-particle distance at which particles are created in hadronic collisions.
This talk discussed the characterization of the source in high-energy proton-proton collisions at the LHC, studied with the ALICE experiment.

Speaker: Daniel Battistini (Czech Technical University in Prague)

Decin26_source.pdf

17:50 The Coulomb problem in three-body systems

One of the most challenging problems in the description of three-body scattering wave functions is the long-range nature of the Coulomb interaction, whose effects cannot be neglected even at large particle separations. An approximate solution can be obtained using screened Coulomb potentials. An ideal test of this approximation can be performed using correlation functions of identical pions, for which only Coulomb and quantum-statistical effects are present as the strong interaction is expected to be negligible.

In this work, the three-body wave function and correlation function for identical pions are calculated using screened Coulomb potentials and compared with measurements performed by ALICE in Pb-Pb collisions.

Speaker: Roberta Ferioli (Czech Technical University in Pragu)

3body_Coulomb_Decin-3.pdf

19:00 → 21:00 Dinner

Thursday 10 September

08:30 → 09:30 Breakfast

10:00 → 11:30 Machine Learning

Convener: Marek Matas (České vysoké učení technické v Praze)

10:00 Machine Learning for data analysis

Machine learning has become a standard tool in many physics analyses.
This contribution presents the use of classification algorithms based on boosted decision trees for efficiently selecting hadron candidates.
Results from the ALICE Collaboration which use this method are also presented.

Speaker: Daniel Battistini (Czech Technical University in Prague)

decin_ml_pub.pdf

10:30 Unfolding with Omnifold (with python examples)

Detector effects distort every measured particle-physics distribution, and classical binned unfolding methods become impractical once more than one or two observables are unfolded jointly, since the number of bins needed grows exponentially with dimensionality. OmniFold sidesteps this limitation with an iterative, unbinned reweighting scheme: two classifiers, alternately trained at detector and particle level, learn the density ratio between simulation and data and convert it directly into per-event weights, without ever binning the data. This talk introduces the algorithm from first principles — density-ratio estimation via classifiers, the two-step pull/push iteration, and why it scales naturally to many observables at once — and then walks through a complete, runnable Python example built on real ALICE ultra-peripheral coherent J/ψ photoproduction data, using the public omnifold package. By the end, attendees — students and researchers new to the method — will be equipped to set up and run OmniFold on their own analyses.

Speaker: Roman Lavička (CTU FNSPE)

OmniFold_RL.pdf

UnfoldJpsiMid.ipynb

11:00 KAN

A brief introduction to multi-layer-percepton (MLP) networks is used
to motivate the concept of Kolmogorov-Arnorld networks (KAN). The
implementation used for the original paper is discussed. As a
necessary step B-splines are presented. Examples are discussed and a
potential application relevant for the workshop is mentioned.
The presentation is organised in an interactive format to encourage
the participation of the public.

Speakers: Guillermo Contreras (FJFI), Jesus Guillermo Contreras

KAN.pdf

11:30 → 11:50 Wrap-up

Speakers: Marek Matas (České vysoké učení technické v Praze), Roman Lavička (CTU FNSPE)

12:00 → 14:00 Lunch