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The 2023 EIC Early Career (EC) Workshop will take place from July 23-24, 2023 at Warsaw University, Warsaw, Poland.
This event is dedicated to students and postdocs but is open to everyone. The meeting will be run in a hybrid mode with the in-person meeting in Warsaw and remotely on Zoom.
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Remote
Studying high-energy hadronic scattering processes to understand the structure
of nuclei has been the focus of experimental and theoretical studies for more
than three decades now. The Color Glass Condensate(CGC) effective theory has
been developed and used to study high-energy proton-nucleus (pA) collisions in
particular. One of the main approximations adopted in the CGC is the so-called
eikonal approximation, which amounts to neglecting power-suppressed corrections
in the high-energy limit. This approximation is well justified for asymptotically
high energies, however, corrections to it might be sizable in practice, in
particular at relativistic heavy ion collider (RHIC) and upcoming electron ion
collider (EIC).
In this talk, I will briefly review the eikonal approximation and present the computation
of a gluon propagator through the target at next-to-eikonal accuracy.
Furthermore, I will present its application to gluon production in pA collisions.
We present exploratory analyses of the 3D gluon content of the proton via a study of polarized gluon TMDs at leading-twist, calculated in a spectator model for the parent nucleon. Our approach encodes a flexible parameterization for the spectator-mass density, suited to describe both moderate- and small-x effects. Particular attention will be paid phenomenological applications to angular modulations and spin asymmetries, such as the Boer-Mulders and the Sivers effects. These studies relevant in the investigation of gluon dynamics inside nucleons and nuclei, which represents a major goal of new-generation colliding machines.
Remote
S.B.L. Amar1,2, amar@frib.msu.edu/netaby1@yahoo.fr
O. Ka2, oumar.ka@ucad.edu.sn
P. Guèye1, gueye@frib.msu.edu
T. Baumann1, baumann@frib.msu.edu
1 Facility for Rare Isotope Beams, Michigan State University, 640 South Shaw Lane, East Lansing, MI 48824
2 Cheikh Anta Diop University, Faculté des Sciences et Techniques, Dakar, Senegal
Abstract. The study of unstable nuclei far from β-stability through fragmentation of heavy-ion beams is one of the most used approaches in low to intermediate energy nuclear physics to gain insights into their nuclear structure and the reaction mechanisms. The impact would be important for nuclear astrophysics, fundamental interactions as well as applications in, e.g., medicine, industry, or homeland security.
The Facility for Rare Isotope Beams (FRIB) started its operation in May 2022 and is expected to produce upward of 1,000 predicted new isotopes for basic and applied nuclear science research. FRIB uses intensively the LISE++ and GEANT4 tools to model experimental setups. However, there is so far no comprehensive and systematic validation of these two methods against each other. A powerful formula to calculate the fragmenting projectile cross section down to a few milli or nano-barn, called EPAX (Empirical Parametrized CROSS section) is implemented in LISE++ and is based on experimental data existing in the literature. The empirical formula has been modified twice for better agreement with measured data. In this communication, we will present a comparative study of the distributions of the total cross section of the fragment nuclei between GEANT4 hadronic physics models and EPAX using LISE++ interface.
To perform this study, a 140 MeV/u beam of 40Ar is used to impinge a 9Be target through the fragmentation process. Five GEANT4 physics models (e.g., Shielding, QGSP_BERT, QGSP_BIC, FTFP_BERT and QBBC) have been identified as adequate to describe these reactions. Their predictions are compared to those from EPAX.
The identification of the discrepancies between GEANT4 and EPAX for rare isotopes will lead to the development of a systematic validation suite to benchmark each code for their future versions. This will allow also to offer guidance for their usage to low- and high-energy nuclear physics communities.
Key words. rare isotopes – projectile fragmentation reaction – GEANT4 – EPAX
Starting from the Weinberg formalism for the construction of fields for arbitrary spin, we propose an algorithm for the construction of the independent operators that enter the scattering amplitude associated with electromagnetic observables. This procedure is advantageous for the systematic study of the structure of hadrons and nuclei, particularly in the case of spin-dependent observables. As higher spin targets exhibit new features in their hadronic structure, the investigation of these properties can enhance our understanding of the strong force. To demonstrate the efficacy of this method, we apply it to the description of elastic electroscattering on a spin 1 target, such as the deuteron. The results of calculations within Instant and Light-Front forms of dynamics are presented, together with a systematic identification of the electromagnetic form factors and potential extensions of the formalism to hard exclusive processes on the deuteron.
A crucial component to the Electron Ion Collider (EIC) program is the collider luminosity, with a target absolute (relative) uncertainty of less than 1% (exceeding 10$^{−4}$ in precision). The luminosity determination will be achieved employing two complementary approaches, one by direct detection of bremsstrahlung photons and another using a Pair Spectrometer (PS) which utilizes e+e- conversions of the bremsstrahlung photons. The anticipated higher luminosity at the EIC than HERA,which achieved a recision of ≈ 2%, presents several new challenges that necessitate major improvements to the PS baseline design. More specifically, the novel design now includes a thin converter foil, sweeper and analyzer magnet, a helium/vacuum chamber, tracking layers, and modern EM calorimeters. We present estimates to the luminosity uncertainties for the electron Proton-Ion Collider (ePIC) experiment at the EIC through dedicated simulations using the PS.
We report on the characterization of different types of Silicon Photomultipliers (SiPMs). These sensors are based on Single Photon Avalanche Diodes (SPADs) operating in Geiger regime. All the single SPAD cells have an integrating quenching resistor used to interrupt the avalanche effect lowering the inverse polarization tension. SiPMs are capable of detecting and resolving single photons. Thus, they are the technology of choice to equipe the dual RICH detector (dRICH) at the ePIC experiment at the future Electron-Ion Collider. One of down sides of SiPMs is the presence of a Dark Count Rate (DCR) caused by thermal electrons which also depends on the bias voltage applied to the sensor. Such an effect can be minimized by lowering temperature of the sensors. We will show several measurements of DCR at different temperatures (-20°C, -25°C, -30°C). Other sources of noise like Cross Talk between to matrix elements and Afterpulsing due to a subsequent signal caused by electrons produced in the avalanche effect are also evaluated. Furthermore, in order to estimate radiation damage to the sensors, we have exposed them to different doses of absorbed protons and neutrons using accelerators at the Trento and Legnaro facilities. The same measurements, repeated after irradiation, highlight the degradation in the performance of the tested sensors.
Silicon photomultipliers (SiPMs) are the candidatel photodetector
technologies for the dual-radiator Ring-Imaging Cherenkov (dRICH) detector of the ePIC experiment at the Electron-Ion Collider (EIC).
SiPMs are a cheap and reliable solution with the main drawback being they are radiation sensitive devices. In an effort to understand how these sensors could deteriorate in themoderate radiation environment at their location in the dRICH detector several irradiation campaigns have been performed in 2021 and 2022 and a new one is currently carried out in 2023.
Sensors from various manufacturers were characterised at various stages: when new, after irradiation and after the following annealing cycle(s). The latter is a technique that warms the device to high temperature (~180°C) to recover the displacement damage by means of thermal excitation. This cure method recovers a large fraction of the detector performance and can be performed in various fashions with each having their advantages and drawbacks.
In this talk I will discuss the results of the characterisation campaigns and the present one so far, with a focus on the strategies we foresee to study to mitigate and recover the radiation damage for the future detector. In particular the results for the annealing procedures in an external oven and by directly heating the device through direct and reverse current will be discussed.
We are conducting R&D for the ePIC electron-endcap electromagnetic calorimeter. It will be composed of bars of scintillating PWO crystals, that we characterized in particular by measuring their temperature-dependent light yield, their optical transmittance and their radiation hardness. The anticipated readout with silicon photomultipliers (SiPMS) is now being investigated. The SiPMs need to have a large dynamic range to detect energies spreading over several orders of magnitude, so we are interested in characterizing SiPMs with a large number of pixels. The measurement is challenging due to their low gain and high dark rate. Tests were performed with LED light to measure their linearity, and determine how they could meet the requirements of ePIC. Measurements are currently on-going to understand the minimal energy that could be detected using this SiPM solution. We will report on recent results of these tests and outline the next steps towards finalizing the readout concept for this detector subsystem.
We report the results of the test beam studies performed on a prototype for the high-granularity calorimeter insert for the ePIC detector at the EIC.
The ECAL-sized prototype was constructed using layers of Fe absorber plates and scintillating tiles with silicon photomultipliers. A 4 GeV positron beam from Jefferson Laboratory's Hall D pair spectrometer was used to evaluate its performance. These studies serve as a proof-of-concept and will inform future design improvements and construction techniques.
Measurement of jets and their substructure will provide valuable information about the properties of the struck quarks and their radiative properties in Deep-Inelastic Scattering events. The ePIC Barrel Hadronic Calorimeter (BHCal) will be a critical tool for such measurements. By enabling the measurement of the neutral hadronic component of jets, the BHCal will complement the Barrel Electromagnetic Calorimeter and improve our knowledge of the jet energy scale. However, to obtain a physically meaningful measurement, the response of the BHCal must be properly calibrated. In this presentation we provide a snapshot of ongoing studies exploring the use of Machine Learning to calibrate the response of the BHCal. Furthermore, we discuss ongoing efforts to characterize the performance of the BHCal in jet measurements while also providing a general overview of the detector and its design.
e study the formation of photon+jet in pp and pPb collisions by implementing the small-x Improved Transverse Momentum Dependent (ITMD) factorization framework, which is ideal for forward particle generation at relatively large transverse momenta and small x. The Color Glass Condensate theory serves as the foundation for the ITMD factorization framework. We analyze the transverse momentum distributions, azimuthal correlations, and other important observables at various center-of-mass energies. We observe that this study has the potential to serve as a powerful probe of saturation effects, adding to our understanding of the gluon saturation phenomena and shed light on the fundamental elements of Quantum Chromodynamics (QCD) at high energies. The ITMD factorization framework is applied here via the Monte Carlo event generator KaTie. Based on: ArXiv:2306.04706
We present recent results for the dijet production in proton-proton and proton-lead collisions at the LHC, focusing on the forward rapidity regions detected by the ATLAS calorimeter and the upcoming FoCal extension of the ALICE detector. Our computation utilizes the KATIE Monte Carlo program, which incorporates the small-x improved TMD (ITMD) formalism. The presentation is based on https://doi.org/10.1007/JHEP12(2022)131 , https://arxiv.org/abs/2306.17513 .
The upcoming Electron Ion Collider (EIC) at Brookhaven National Lab will provide novel opportunities to study the structure of nucleons and nuclei. Exclusive reactions in particular, such as Deeply Virtual Compton Scattering (DVCS) and Deeply Virtual Meson Production (DVMP), have clean final states which allow us to effectively extract Generalised Parton Distribution (GPDs). This makes them important topographic tools in understanding the quark-gluon structure of the nucleon and nuclei. We will present the current status of these topics from the ePIC detector.
$u$-channel VCS is Compton scattering of a photon off of a proton, involving a near-maximal momentum transfer between the two. In the $\gamma^*p$ center-of-mass frame, the photon and proton recoil backward. The $u$-channel contribution to the VCS cross section is not well understood and may encode unique information about parton distributions within the proton. Recent simulations of $u$-channel VCS at the EIC will be presented. Prospects for detecting these events in a future ePIC detector will be discussed, as well as methods to reduce the background from $u$-channel $\pi^0$ production.
Generalized parton distributions (GPDs) are off-forward matrix elements of quark and gluon operators that enclose information on the total angular momentum of partons, and so on the spin of hadrons (cf. EMC measurements and spin puzzle). In addition, GPDs enable tomography of the nucleon allowing to study spatial distribution of partons as a function of their momentum. To access GPDs one needs to consider exclusive processes, such as deeply virtual and timelike Compton scattering (DVCS and TCS). At LO these processes are mainly sensitive to GPDs in a restricted kinematic domain, namely $x = \xi$, where $x$ represents the average fraction of longitudinal momentum carried by an active parton, while $\xi$ is the so-called skewness variable. The process that avoids this constraint is double deeply virtual Compton scattering (DDVCS) for which an electron scatters off a nucleon and produces a lepton pair. The extra virtuality with respect to DVCS and TCS allows for LO access to GPDs at $x\neq\xi$.
Due to the lepton-pair production, DDVCS cross-section is smaller than that of DVCS by roughly a factor $\alpha_{\rm em}$. Consequently, measurements of DDVCS with the relevant statistics for GPDs extraction require experiments with large luminosity. One of them will be the Electron-Ion Collider (EIC). In this talk, the importance of DDVCS for GPD physics, being one of the pillars of the EIC programme, will be highlighted. Elements of impact studies for EIC and JLab have been worked out by means of PARTONS software and EpIC Monte Carlo event generator. The phenomenological study lays on a new formulation of DDVCS based on the methods developed by R. Kleiss and W. J. Stirling in the 1980s, that will be shown as well.
The far backward region contains several detectors that are critical for luminosity monitoring. Luminosity measurements provide the required normalisation for all physics studies, without them, determining absolute cross sections would not be possible. The detectors in this region are also vital for some studies, such as XYZ spectroscopy. In this talk, I will provide a brief overview of the detectors in this region. I will highlight the latest designs for these detectors and the technologies that will be utilise, with a focus on ongoing efforts at York to design and build the luminosity pair spectrometer. I will also give a brief overview of some of the physics measurements enabled by these detectors.
Coherent vector meson (VM) production provides insights into the gluon structure functions of nuclei and is sensitive to gluon saturation effects. Various works have been dedicated to studying coherent VM production at various ranges of photon virtuality (Q2). The main challenge in reconstructing diffractive observables (like the momentum transfer) arises in accurately reconstructing the energy and the momentum of the scattering electrons, particularly as the virtuality of the photon increases.
In this presentation, we will present a feasibility study of observing coherent VM production at low values of Q2, focusing on the reconstruction of event kinematics at these scales.
Remote
We investigated the X(3872) exotic meson candidate and explored the feasibility of researching it using the future Electron-Ion Collider (EIC). X(3872) is a tetraquark candidate: a meson that is composed of four quarks but requires additional investigation. We completed the study based upon the generated values for 10,000 events. The parameters of the exotic meson explored include Mandelstam variables, mass, and pseudorapidity, among others.
Remote
Inclusive forward particle production in proton-nucleus collisions at small x is an important process in high-energy nuclear collisions. It has been proven that the negative NLO cross section problem in the higher momentum regime of forward rapidity single inclusive hadron production in pA collisions can be solved through the threshold resummation method. In this report, I will present several phenomenological applications of the forward particle production in pA process in Color Glass Condensate framework in our work. Specifically, we compare our theoretical results with the latest experimental data from the LHCb collaboration, including neutral pion, charged hadron, and D0 meson production, and conclude that our theoretical results are in good agreement with the experimental data. In our numerical part, we use different several parameters than in previous articles. The fact that our theoretical result are agree well with experimental data shows parameters we chose are proper. Furthermore, our numerical results demonstrate that the threshold resummation method is an effective approach for solving this negative cross section problem.
Remote.
In this talk, I will introduce the concept of the nucleon energy energy correlator (neec). I will argue how this quantity can be measured in the dis process and present the NLL results
To consolidate figures of merit of a variety of measurements at the Electron-Ion-Collider, it is essential to include radiative corrections in simulations of electron-proton and electron-nucleus collisions. For the time being, there do not exist any automated simulation tools for such reactions,including even only next-to-leading order (NLO) radiative corrections.
In this talk, I will present our implementation of photoproduction, where the photon is either coming from an electron or from a proton in an ultra-peripheral collision at the LHC. We perform the calculations at NLO in the fixed-order mode within MadGraph5_aMC@NLO, a framework for (N)LO computation, intensively used at the LHC.
About 50 years ago, it was discovered that $\Lambda$ hyperons are produced polarized in collisions of unpolarized protons on beryllium. Despite enormous experimental and theoretical efforts, the origin of this polarization remains inconclusive to date. The $\Lambda$ polarization has also been observed in various collision systems, from $e^+e^-$ to heavy-ion collisions. A recently proposed technique for the investigation of the $\Lambda$ hyperon polarization is a measurement of $\Lambda\bar{\Lambda}$, $\Lambda\Lambda$, and $\bar{\Lambda}\bar{\Lambda}$ spin-spin correlations. This technique is expected to help understand if the polarization is generated at early stages of the collisions, e.g. from initial state parton spin correlation, or if it is a final state effect originating from hadronization. In this talk, I present prospects of performing the $\Lambda$ hyperon pair spin-spin correlation measurement at ePIC in context of results from other experiments from measurements of single $\Lambda$ hyperon polarization.
We explore the potential for SiPM-on-tile calorimetry at the EIC in a ZDC. We find that staggering the layers of scintillating cells, we can significantly improve shower position reconstruction. We also show that a SiPM-on-tile ZDC meets the Yellow Report requirements, and has the potential for further improvements.
Soft photon emission from excited nuclei at the Electron-Ion Collider is a largely unexplored but potentially measurable phenomenon. We are interested in understanding the capabilities of the B0 EM calorimeter to detect and measure these, or any, soft photons.
In the talk, I will explain how we use BeAGLE-generated data of excited Pb Ions, produced from incoherent J/psi production in ePb collisions at a hadron beam energy of 108 GeV/nucleon, to study the soft photons emitted during the de-excitation process and to confirm that the B0 detector has adequate acceptance for such soft photons.