# 57. International Winter Meeting on Nuclear Physics

Europe/Berlin
Bormio, Italy

#### Bormio, Italy

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Description
Long-standing conference bringing together researchers and students from various fields of subatomic physics. The conference location is Bormio, a beautiful mountain resort in the Italian Alps.
Participants
• Aleksandra Ciemny
• Amer Alqaaod
• Andreas Mathis
• ANGELO pagano
• Aurora Tumino
• Bernhard Hohlweger
• Burkhard Kolb
• Carlo Gustavino
• Carlo Mancini-Terracciano
• Charles Horowitz
• Chloë Hebborn
• Christian Fischer
• Claudia Patrignani
• Concettina Sfienti
• Cristiano Galbiati
• Dalibor Zakoucky
• Dariusz Miskowiec
• Dean Lee
• Dmitry Testov
• Edda Gschwendtner
• Emanuele Vincenzo Pagano
• EMIKO HIYAMA
• Fausto Casaburo
• Francesca Bellini
• Francesco Forti
• Francis Halzen
• Frederic Colomer
• Geirr Sletten
• Georg Wolschin
• Gianluca Stellin
• GIULIA MANCA
• Greg Landsberg
• Hans-Thomas Janka
• Harald Merkel
• Herbert Hübel
• Hermann Wolter
• Isao Tanihata
• Jan Fiete Grosse-Oetringhaus
• Joana Wirth
• John Harris
• John Sharpey-Schafer
• Krzysztof Nowakowski
• laura fabbietti
• Laura Moschini
• Leszek Kosarzewski
• Luciano Musa
• Marcel Merk
• Mariana Nanova
• Martin Ivanov
• Matteo Franchini
• Micol De Simoni
• Mikhail Barabanov
• Mitko Gaidarov
• Natalia Sokołowska
• Patrick Achenbach
• Pepe Guelker
• Pierluigi Campana
• Pierre Capel
• Randolf Pohl
• Rene Reifarth
• Ruediger Haake
• Ryan Mitchell
• Shiro Matoba
• Simon Kegel
• Stan Lai
• Stefan Leupold
• Stefan Lunkenheimer
• Stefan Schoenert
• Steffen Maurus
• Stephan Aulenbacher
• Takashi Nakamura
• Vanek Jan
• Victoria Durant
• Wolfgang Kuehn
• Wolfgang Trautmann
• Monday, 21 January
• 06:00 08:00
Pre-Conference School: Sunday Lectures
• 06:00
Selected Topics in Flavour Physics 10m
Speaker: Prof. Marcel Merk (Nikhef)
• 06:10
Selected Topics in Heavy Ion Collisions 10m
Speaker: Prof. John Harris (Yale University)
• 06:20
Selected topics in Nuclear Structures and Astrophysics 10m
Speaker: Prof. Pierre Capel (Université Libre de Bruxelles (ULB))
• 06:30
Selected topics in Hadron Physics 10m
Speaker: Dr Harald Merkel (Institut für Kernphysik, Johannes Gutenberg-Universität Mainz)
• 09:00 13:10
Monday Morning Session
Conveners: Prof. Concettina Sfienti (Johannes Gutenberg-Universität Mainz) , Prof. Laura Fabbietti (excellence cluster 'universe')
• 09:00
Welcome 10m
Speakers: Prof. Concettina Sfienti (Johannes Gutenberg-Universität Mainz) , Prof. laura fabbietti (Technische Universitaet Muenchen)
• 09:10
Latest Results from the CMS Experiment 45m
In this broad overview talk I'll cover the latest results from the CMS experiment at the LHC, with the focus on a few most important topics in high-pT and heavy ion physics,
Speaker: Prof. Greg Landsberg (Brown University)
• 09:55
Neutron stars and the equation of state of dense matter 45m
I review neutron star structure and how this depends on the equation of state (pressure vs density) of dense matter. Constraints on the equation of state from laboratory experiments and astronomical observations with X-rays, neutrinos, and gravitational waves will be discussed.
Speaker: Prof. Charles Horowitz (Indiana University)
• 11:10
Recent results of the BES-III experiment 45m
Recent results of the BES-III experiment
Speaker: Ryan Mitchell (Indiana University)
• 11:55
Flavour results at LHCb 30m
Flavour results at LHCb
Speaker: Dr Pierluigi Campana (LNF-INFN)
• 17:00 19:00
Monday Afternoon Session: Poster Session
Convener: Prof. Pierre Capel (Université Libre de Bruxelles (ULB))
• 17:00
Studies of the nucleosynthesis $^{12}\mathrm C(\alpha,\gamma)^{16}\mathrm O$ in inverse kinematic for the MAGIX experiment on MESA 3m
MAGIX is a versatile fixed-target experiment and will be built on the new accelerator MESA (Mainz Energy-Recovering Superconducting Accelerator) in Mainz. The accelerator will deliver polarized electron beams with currents up to $1\,\mathrm{mA}$ and energy up to $105\,\mathrm{MeV}$. Using its internal gas-target, MAGIX will reach a luminosity of $\mathcal{O}(10^{35}\,\mathrm{cm}^{−2}\mathrm{s}^{−1})$. This allows to study processes with very low cross section at small momentum transfer in a rich physical program. The poster presents the planned measurements of the nucleosynthesis process $^{12}\mathrm C(\alpha,\gamma)^{16}\mathrm O$ to determine its S-factor. In the experiment we will scatter electrons on oxygen atoms and we will detect the scattered electrons in coincidence with the produced $\alpha$-particles. With this measurement we will determine the cross section of the inverse kinematic as a function of the outgoing center of mass energy of the carbon-$\alpha$-system to calculate the S-factor. Hereby we will present the results of the actual simulations and the parameter range that MAGIX will be able to explore. Additionally the planned experimental setup will be discussed.
Speaker: Mr Stefan Lunkenheimer (KPH)
• 17:03
15C structure and dynamics: coupling Halo EFT to reaction models for transfer, breakup and radiative capture 3m
We study various reactions involving the one-neutron halo nucleus 15C using a single structure model based on Halo EFT. First, we determine the low-energy constants needed in this description of 15C to reproduce both the one-neutron binding energy of 15C ground state and the asymptotic normalization coefficient (ANC) extracted through the analysis of the 14C(d,p)15C transfer reaction at 17.06 MeV [1,2]. Then, we study the 15C breakup at high (605 AMeV [3]) and intermediate (68 AMeV [4]) energies using an eikonal model with a consistent treatment of nuclear and Coulomb interactions at all orders, which takes into account proper relativistic corrections. We show the importance of the inclusion of relativistic corrections in the former case. Finally, we study the 14C(n,gamma)15C radiative capture comparing our results to the direct measurements performed by Reifarth et al. [5]. Our theoretical predictions are in excellent agreement with the experimental data for each reaction, thus assessing the robustness of the structure model provided for this nucleus. [1] A. M. Mukhamedzhanov et al. Phys. Rev. C 84, 024616 (2011). [2] J. Yang and P. Capel, Phys. Rev. C 98, 054602 (2018). [3] U. D. Pramanik et al. Phys. Lett. B551, 63 (2003). [4] T. Nakamura et al. Phys. Rev. C 79, 035805 (2009). [5] R. Reifarth et al. Phys. Rev. C 77, 015804 (2008).
Speaker: Dr Laura Moschini (Université libre de Bruxelles (ULB))
• 17:06
Measurements of open-charm hadrons in heavy-ion collisions by the STAR experiment 3m
Charm quarks are primarily produced at early stages of ultra-relativistic heavy-ion collisions and can therefore probe the Quark-Gluon Plasma (QGP) throughout its whole evolution. Final-state open-charm hadrons are commonly used to experimentally study the charm quark interaction with the QGP. Thanks to the precise secondary vertex reconstruction provided by the Heavy Flavor Tracker (HFT), STAR is able to directly reconstruct D$^\pm$, D$^0$, D$_\textrm{s}$, and $\Lambda_\textrm{c}^\pm$ via their hadronic decay channels. Moreover, the topological cuts for signal extraction are optimized using supervised machine learning techniques. In this talk, we will present an overview of recent open charm results from the STAR experiment. In particular, the nuclear modification factors of open-charm mesons, D$_\textrm{s}$/D$^0$ and $\Lambda_\textrm{c}^\pm$/D$^0$ ratios as functions of transverse momentum and collision centrality will be discussed together with their physics implications.
Speaker: Vanek Jan (Nuclear Physics Institute, Czech Academy of Sciences)
• 17:09
Peripherality in inclusive nuclear breakup of halo nuclei 3m
The development of Radioactive-Ion Beams (RIBs) in the early 80s has enabled the study of exotic nuclei far from stability. Halo nuclei are among the most peculiar structures discovered since then, they have one or two loosely-bound nucleons which tunnel far from the core of the nucleus, causing their matter radius to be much larger than stable nuclei [1]. Their short lifetimes make their analysis through usual spectroscopic techniques impossible, therefore indirect methods, such as reaction processes, have to be used. To infer precise information about the structure of these exotic nuclei from reaction measurements, an accurate reaction model coupled to a realistic description of the nucleus is needed. The eikonal model provides a simple interpretation of the collision and is very efficient from a computational point-of-view. However, it has several flaws: it does not treat properly the dynamics of the projectile during the reaction, in its standard form it has convergence issues to compute breakup observables due to the Coulomb interaction and it is valid only at energies higher than 50 MeV/nucleon. In this work, we study corrections to the eikonal model to address these issues and we analyse their efficiencies in the cases of elastic scattering and breakup of one-neutron halo nuclei. As experimental facilities such as HIE-ISOLDE at CERN and ReA12 at MSU provide RIB around 10 MeV/nucleon, extending the validity of the eikonal model to such energies would be of great interest. To do so, we study two corrections which aim to improve the deflection of the projectile due to its interaction with the target. The first correction relies on a semi-classical approach [2] while the second is based on an exact correspondence with the partial-wave expansion [3]. Both corrections improve the elastic-scattering of one-neutron halo nuclei at 10 MeV/nucleon but fails to describe breakup observables [4,5]. We have also studied corrections to better account for the dynamics of the projectile during the collision. This might improve the eikonal analyses of inclusive measurements of breakup reactions. [1] I. Tanihata, J. Phys. G **22**, 157 (1996). [2] C. E. Aguiar, F. Zardi, and A. Vitturi, Phys. Rev. C **56**, 1511 (1997). [3] J. M. Brooke, J. S. Al-Khalili, and J. A. Tostevin, Phys. Rev. C **59**, 1560 (1999). [4] C. Hebborn and P. Capel, Phys. Rev. C **96**, 054607 (2017). [5] C. Hebborn and P. Capel, Phys. Rev. C **98**, 044610 (2018).
Speaker: Ms Chloë Hebborn (Université libre de Bruxelles)
• 17:12
Meson-baryon interaction in the Fock-Tani formalism 3m
The Fock-Tani formalism is a first principle method to obtain effective interactions from microscopic Hamiltonians. The idea consists in a change of representation such that the operators associated with composite particles could be rewritten in operators who satisfy the canonical anticomutation relations. Starting from Fock space and using creation and annihilation operators to the constituents' particles, we consider a system contending quarks and antiquarks which could form bonded-states. In this new representation, the meson/baryon states can be constructed from meson/baryon creation operators. Originally derived for meson-meson or baryon-baryon scattering, we will present the corresponding equations for meson-baryon scattering.
• 17:15
Constraining the Λ-Λ interaction with femtoscopy in small systems at the LHC 3m
Pioneering studies by the ALICE Collaboration have demonstrated the potential of employing femtoscopy to investigate and constrain baryon-baryon interactions with unprecedented precision. In particular, the small size of the particle-emitting source in pp and p-Pb collision systems at ultrarelativistic energies is well suited to study short-ranged strong potentials. Newly developed analysis tools allow for the comparison of the measured correlation function between the particle pairs of interest to theoretical predictions using either potentials or wave functions as an input. In this contribution, we present measurements of Λ–Λ correlations by the ALICE Collaboration in pp collisions at √s = 7 and 13 TeV and p–Pb at √s$_{\mathrm{NN}}$ = 5.02 TeV. The interaction among the Λ–Λ pairs is studied with unprecedented precision, and the data are found to agree with hypernuclei results and state of the art lattice computations. Furthermore, by testing the compatibility of different model predictions and scattering parameters with the high precision data, the interaction is investigated. The experimental data tightly constrain the existence and the binding energy of a hypothetical H-dibaryon state.
Speaker: Andreas Mathis (Technische Universität München, Physik Department E62)
• 17:18
Cascading decays of nucleon resonances via meson-pair emission? 3m
Photoproduction of mesons provides important information about the ex- citation spectrum of the nucleon that is still not suciently understood despite various long-lasting experimental and theoretical eorts [1]. Reac- tions with multiple-meson nal states are important, in particular 0 since the acts as an isospin lter and provides information on the nature of the intermediate resonances. Particular attention has been paid to the recently claimed narrow structure observed at 1685 MeV in the N channel [2]. We have studied the two-meson photoproduction with the CB/TAPS detector system at the ELSA accelerator in Bonn in the reaction p! p0. High statistics have been obtained in irradiating a liquid hydrogen target with photon beams in the incident energy range from 0.9 to 3.0 GeV. A kine- matic t has been used in the reconstruction and identication of the exit channels. Preliminary results on the search for the narrow structure at 1685 MeV will be presented. [1] V. Crede and W. Roberts, Rep. Prog. Phys. 76 (2013) 076301 [2] V. Kuznetsov et al., JETP Letters 106 (2017) 693 *Funded by DFG(SFB/TR-16)
Speaker: Dr Mariana Nanova (II. Pays. Institut, University of Giessen, Giessen, Germany)
• 17:21
Neutronic Analysis for the Effects of High-Level Radioactive Waste Distribution on Subcritical Multiplication Parameters in ADS Reactor 3m
The transmutation of high-level radioactive waste (HLW) for nuclear waste management attracted attention of many countries, and is a subject of current research in many European and national project[1][2]. This interest comes from the increase of accumulated nuclear waste due to operation of nuclear power plants, and the needs to minimize the environmental and proliferation threats. Innovative nuclear reactor concepts like accelerator driven systems (ADS) are currently in development that predict to play an effective role in the transmutation process of transuranium elements, in particular of minor actinides (MA) and Long Lived Fission Product (LLFP) to reduce the radiotoxicity risk [3]. In this study, the effect of high level radioactive waste distribution on the neutron characteristics like subcritical multiplication parameters and source efficiency are numerically investigated in three different configurations for simple model of Accelerator Driven System (ADS) reactor consist of two zones, inner region with fast neutron spectra and outer region with thermal neutron spectra, and the subcritical core coupled with external neutron source. The calculations are conducted by using Monte Carlo N-particle Transport code. [1] L. García, J. Pérez, C. García, A. Escrivá, J. Rosales, and A. Abánades, “Calculation of the packing fraction in a pebble-bed ADS and redesigning of the Transmutation Advanced Device for Sustainable Energy Applications (TADSEA),” Nucl. Eng. Des., vol. 253, pp. 142–152, 2012. [2] D. De Bruyn, H. A. Abderrahim, P. Baeten, and P. Leysen, “The MYRRHA ADS Project in Belgium Enters the Front End Engineering Phase,” Phys. Procedia, 2015. [3] P. K. Zhivkov, “Energy Production and Transmutation of Nuclear Waste by Accelerator Driven Systems,” in Journal of Physics: Conference Series, 2018.
Speaker: Dr Amer A. Al Qaaod (Postdoc fellowship)
• 17:24
Simulation and construction of an open TPC 3m
Starting from the source, through the cavities, to the target and into the spectrometers the electrons at MESA/MAGIX do not have to pass any windows. Just before entering the detection-system one barrier has to be passed, which is unfortunate, but essential to seperate the vacuum in the spectrometers from the counting-gas inside the detector. For the track-reconstruction of low energy electrons (< 105 MeV) every bit of material is crucial, as the best achievable resolution is lowered by multiple scattering in traversed material. The classic approach for TPCs is to homogenise the drift field by surrounding the area with a field-cage, consisting of copper and kapton. To restrict the material barrier to an absolute minimum, we want to get rid of the field-cage on the entrance face of the detector. In this contribution new ideas on how to accomplish this, without distorting the electrical field are presented.
Speaker: Mr Jakob, Manuel, Philip, Pepe Guelker (JGU)
• 17:27
Detection of primary photons in high energy cosmic rays using Cherenkov imaging and surface detectors 3m
Speaker: Mr Fausto Casaburo (University La Sapienza)
• 17:30
The Silicon Tracking System of CBM getting ready for experiment 3m
The Compressed Baryonic Matter (CBM) experiment at the FAIR facility will explore the QCD phase diagram at very high baryon densities, where a first order phase transition from hadronic to partonic matter as well as a chiral phase transition is expected to occur. The Silicon Tracking System is the central detector for charged-particle identification and momentum measurement. It is designed to measure up to 1000 particles in A+A collision rates between 0.1 and 10 MHz, to achieve a momentum resolution in a 1Tm dipole magnetic field of better than 2%, and to be capable of identifying complex particle decays topologies, e.g., such with strangeness content. The STS employs high-granularity double-sided sensors matching the non-uniform track density and fast self-triggering electronics with a free streaming data acquisition system and online event selection. With the resulting 1.8 million readout channels, it poses the most demanding requirements regarding bandwidth and density of all CBM detectors. The STS functional building block is a module consisting of a sensor, micro-cables and two front-end electronics boards. The modules are mounted on carbon fiber support ladders. The silicon sensors provide double-sided segmentation at a strip pitch of 58 µm and 7.5-degree stereo angle. Ultra-thin micro-cables with up to 50cm length transfer the sensor signals to the electronics located out of the detector acceptance. The custom-developed read-out ASIC “STS-XYTER” has a self-triggering architecture that delivers time and amplitude information per channel. Towards the phase 0 of the CBM experiment, mini CBM (mCBM), a precursor of the full CBM with detector units from all subsystems, the STS will contribute with two tracking stations consisting of a total of 13 modules. The mCBM will allow to test and optimize the detector performance, including the data acquisition chain under realistic experimental conditions and its integration with the other subsystems. This presentation aims to show an overview of the development status of the module components, readout chain, first test results and system integration in a framework of the mCBM campaign at SIS18 at GSI.
Speaker: Mr Adrian Rodriguez Rodriguez (Goethe University Frankfurt am Main)
• 17:33
Probing of XYZ meson structure with near threshold pp and pA collisions 3m
The spectroscopy of charmonium-like mesons with masses above the 2mD open charm threshold has been full of surprises and remains poorly understood [1]. The currently most compelling theoretical descriptions of the mysterious XYZ mesons attribute them to hybrid structure with a tightly bound cc\bar diquark [2] or cq(cq')\bar tetraquark [3 - 5] core that strongly couples to S-wave DD\bar molecular-like structures. In this picture, the production of a XYZ particle in high energy hadron collisions and its decays into light hadron plus charmonum final states proceed via the core component of the meson, while decays to pairs of open charmed mesons proceed via the DD\bar component. These ideas have been applied with some success to the X(3872) [2], where a detailed calculation finds a cc\bar core component that is only above 5% of the time with the DD\bar component (mostly D^0D^0\bar) accounting for the rest. In this picture, the X(3872) is compose of three rather disparate components: a small charmonium-like cc\bar core with r_rms < 1 fm, a larger D^+D^- component with r_rms = ħ/\sqrt(2µ+B+) ≈ 1.5 fm and a dominant component D^0D^0\bar with a huge, r_rms = ħ/\sqrt(2µ0B0)> 9 fm spatial extent. Here µ+(µ0) and B+(B0) denote the reduced mass for the D^+D^- (D^0D^0\bar) system and the relevant binding energy |mD + mD - MX(3872)| (B+ = 8.2 MeV, B0 < 0.3 MeV). The different amplitudes and spatial distributions of the D^+D^- and D^0D^0\bar components ensure that the X(3872) is not an isospin eigenstate. Instead it is mostly I = 0, but has a significant (~ 25 %) I = 1 component. In the hybrid scheme, an X(3872) is produced in high energy pA collisions via its compact (r_rms < 1 fm) charmonium-like structure and this rapidity mixes in a time (t ~ ħ/δM) into a huge and fragile, mostly D^0D^0\bar, molecular-like structure. δM is the difference between the X(3872) mass and that of the nearest cc\bar mass pole core state, which we take to be that of the χ_c1(2P) pure charmonium state which is expected to lie about 20 ~ 30 MeV above M_X(3872) [6, 7]. In this case, the mixing time, cτ_mix 5 ~ 10 fm, is much shorter than the lifetime of X(3872) which is cτ_X(3872) > 150 fm [8]. The experiments with proton-proton (pp) and proton-nuclear (pA) collisions with √SpN up to 26 Gev/c and luminosity up to 10^32 cm^-2s^-1 planned at NICA are well suited to test this picture for the X(3872) and, possibly, other XYZ mesons. In near threshold production experiments in the √SpN ≈ 8 GeV energy range, X(3872) mesons can be produced with typical kinetic energies of a few hundred MeV (i.e. with γβ ≈ 0.3). In the case of X(3872), its decay length will be greater than 50 fm while the distance scale for the cc\bar → D^0D^0*\bar transition would be 2 ~ 3 fm. Since the survival probability of an r_rms ~ 9 fm “molecular” inside nuclear matter should be very small, X(3872) meson production on a nuclear target with r_rms ~ 5 fm or more (A ~ 60 or larger) should be strongly quenched. Thus, if the hybrid picture is correct, the atomic number dependence of X(3872) production at fixed √SpN should have a dramatically different behavior than that of the ψ', which is long lived compact charmonium state. The current experimental status of XYZ mesons together with hidden charm tetraquark candidates and present simulations what we might expect from A-dependence of X(3872) mesons in pp and pA collisions are summarized. References [1] S. Olsen, Front. Phys. 10 101401 (2015) [2] S. Takeuchi, K. Shimizu, M. Takizawa, Progr. Theor. Exp. Phys. 2015, 079203 (2015) [3] A. Esposito, A. Pilloni, A.D. Poloza, arXiv:1603.07667[hep-ph] [4] M.Y.Barabanov, A.S.Vodopyanov, S.L.Olsen, A.I.Zinchenko, Phys. Atom. Nuc. 79, 1, 126 (2016) [5] M.Yu. Barabanov, A.S. Vodopyanov, S.L. Olsen, Phys. Scripta 166 014019 (2015) [6] N. Isgur, Phys. Rev. D 32, 189 (1985) [7] K. Olive et al. (PDG), Chin. Phys. C 38, 090001 (2014) [8] The width of X(3872) is experimentally constrained to be Г X(3872) < 1.2 (90% CL) in S.-K. Choi et al (Belle Collaboration), Phys. Rev. D 84, 052004 (2011)
Speaker: Prof. Mikhail Barabanov (JINR)
• 17:36
Nuclear symmetry energy and its components at zero and finite temperatures 3m
We derive the volume and surface components of the nuclear symmetry energy (NSE) and their ratio [1] within the coherent density fluctuation model [2, 3]. The estimations use the results of the model for the NSE in finite nuclei based on the Brueckner and Skyrme energy-density functionals for nuclear matter. The obtained values of these quantities for the Ni, Sn, and Pb isotopic chains are compared with estimations of other approaches which have used available experimental data on binding energies, neutron-skin thicknesses, and excitation energies to isobaric analog states. Apart from the density dependence investigated in our previous works [4, 5, 6], we study also the temperature dependence of the symmetry energy in finite nuclei [7] in the framework of the local density approximation combining it with the self-consistent Skyrme-HFB method using the cylindrical transformed deformed harmonic oscillator basis. The results for the thermal evolution of the NSE in the interval T=0—4 MeV show that its values decrease with temperature. The same formalism is applied to obtain the values of the volume and surface contributions to the NSE and their ratio at finite temperatures [8]. We confirm the existence of "kinks" of these quantities as functions of the mass number at T = 0 MeV for the double closed shell nuclei 78Ni and 132Sn and the lack of "kinks" for the Pb isotopes, as well as the disappearance of these kinks as the temperature increases. References [1] A. N. Antonov, M. K. Gaidarov, P. Sarriguren, and E. Moya de Guerra, Phys. Rev. C 94, 014319 (2016). [2] A.N. Antonov, V.A. Nikolaev, and I.Zh. Petkov, Bulg. J. Phys. 6 (1979) 151; Z. Phys. A 297 (1980) 257; ibid 304 (1982) 239; Nuovo Cimento A 86 (1985) 23; A.N. Antonov et al., ibid 102 (1989) 1701; A.N. Antonov, D.N. Kadrev, and P.E. Hodgson, Phys. Rev. C 50 (1994) 164. [3] A.N. Antonov, P.E. Hodgson, and I.Zh. Petkov, Nucleon Momentum and Density Distributions in Nuclei, Clarendon Press, Oxford (1988); Nucleon Correlations in Nuclei, Springer-Verlag, Berlin-Heidelberg-New York (1993). [4] M. K. Gaidarov, A. N. Antonov, P. Sarriguren, and E. Moya de Guerra, Phys. Rev. C 84, 034316 (2011). [5] M. K. Gaidarov, A. N. Antonov, P. Sarriguren, and E. Moya de Guerra, Phys. Rev. C 85, 064319 (2012). [6] M. K. Gaidarov, P. Sarriguren, A. N. Antonov, and E. Moya de Guerra, Phys. Rev. C 89, 064301 (2014). [7] A. N. Antonov, D. N. Kadrev, M. K. Gaidarov, P. Sarriguren, and E. Moya de Guerra, Phys. Rev. C 95, 024314 (2017). [8] A. N. Antonov, D. N. Kadrev, M. K. Gaidarov, P. Sarriguren, and E. Moya de Guerra, Phys. Rev. C 98, 054315 (2018).
Speaker: Dr Mitko Gaidarov (INRNE-BAS)
• 17:39
β decay of 11 Be 3m
11Be is the neutron - rich nucleus expected to be a β-delayed proton emitter. The very small branching ratio (BR) for this exotic decay mode (∼ 10e−6 ) was determined through indirect observations based on accelerator mass spectrometry (AMS) [1, 2] and resulted to be about two orders of magnitude larger than predicted [3]. The direct measurement of the delayed proton emission probability and energy spectrum is particulary challenging, given the small energy window available (∼ 280 keV). The measurement of the βp energy spectrum is important for estimating the Gamow-Teller strength at high excitation ener- gies and for testing models that predict a direct relation between βp and halo structure. Moreover, recently a new hypothesis which may explain results of the AMS experiment appeared. According to it, the neutron may have another decay channel in which unknown particles are produced in the final state [4, 5]. In order to solve this puzzle, we decided to perform a series of measurements with the Warsaw Optical Time Projection Chamber (OTPC) [6]. First tests were made in February 2018 at JINR in Dubna. Those measurements were focused on studying the behaviour of light nuclei in the region of 11Be in the chosen experimental conditions. Additionally we measured 9C beta decay in which low-energy beta-delayed protons (165 keV) are emitted. The main experiment was performed in August/September 2018 at HIE-ISOLDE in CERN. During this run a large amout of 11Be beta decays was observed. A complementary measurement at LNS in Catania is planned for spring 2019 - during this experiment BR for beta delayd alpha emission from 11Be will be determined. The whole project is extremely challenging and complex, both from physical and tech- nical point of view (low BR for β-delayed protons: 10e−8 ∼ 10e−6 , long half-life: T_1/2 = 13.7 s, and low energy of the protons ∼ 180 keV). It required the development of new solutions for the acquisition system and analysis software. More details on the project and the status of the data analysis will be presented. [1] K. Riisager, Nucl. Phys. A 925, 112 (2014). [2] K. Riisager et al., Phys. Lett. B 732, 305 (2014). [3] M. J. G. Borge, et al. J. Phys. G, 40, 035109 (2013). [4] B. Fornal and B. Grinstein, Phys. Rev. Lett. 120, 191801 (2018). [5] M. Pfützner, K. Riisager, Phys. Rev. C 97, 042501(R) (2018). [6] M. Pomorski et al., Phys. Rev. C 90, 014311 (2014).
Speaker: Ms Natalia Sokołowska (Faculty of Physics, University of Warsaw)
• 17:42
Charged-current quasielastic (anti)neutrino cross sections on 12C with realistic spectral functions including meson-exchange contributions 3m
We present a detailed study of charged-current quasielastic (anti)neutrino scattering cross sections on a $^{12}$C target obtained using a spectral function $S(p,{\cal E})$ that gives a scaling function in accordance with the electron scattering data. The spectral function accounts for the nucleon-nucleon (\emph{NN}) correlations, it has a realistic energy dependence and natural orbitals (NO's) from the Jastrow correlation method are used in its construction~\cite{01, 02, 03}. The results are compared with those when \emph{NN} correlations are not included, namely harmonic-oscillator single-particle wave functions are used instead of NO's. A comparison of the results with recent experiments, as well as to results from the superscaling approach is done. The contribution of two-particle two-hole meson-exchange currents on neutrino--nucleus interactions is also considered within a fully relativistic Fermi gas. The results show a good agreement with the experimental data over the whole range of neutrino energies.
Speaker: Dr Martin Ivanov (INRNE, BAS)
• Tuesday, 22 January
• 09:00 13:30
Tuesday Morning Session
Convener: Wolfgang Kuehn (JLU Giessen)
• 09:00
The AWAKE Experiment 45m
The AWAKE Experiment
Speaker: Dr Edda Gschwendtner (CERN)
• 09:45
Recent developments in nuclear structure theory. 45m
Recent developments in nuclear structure theory.
Speaker: Prof. Dean Lee (Michigan State University)
• 11:00
News from the "proton radius puzzle" 30m
For more than eight years now, the "proton radius puzzle" has let us dream about new physics: Our measurements of muonic hydrogen and muonic deuterium, performed in the CREMA Collabroation at PSI, yielded a proton radius which is more than five standard deviations smaller than the CODATA world average from measurements using electrons, namely precision spectroscopy of atomic hydrogen and deuterium, and elastic electron scattering. A wealth of new experiments has been fueled by this exciting discrepancy, and the first results are now coming in. I will report on several new measurements in atomic hydrogen we have performed at MPQ Garching. These, together with new hydrogen measurements from LKB Paris and York U. Toronto and new elastic electron scattering data from The PRad experiment at Jefferson Lab start to paint a clearer picture on the "proton radius puzzle", albeit not without raising new questions.
Speaker: Prof. Randolf Pohl (Johannes Gutenberg University Mainz)
• 11:30
Speaker: Claudia Patrignani (Università and INFN Bologna)
• 12:00
Antimatter measurements at the LHC and implications for indirect dark matter searches 30m
The observation of anti-deuteron and anti-helium in cosmic rays has been suggested as a smoking gun in indirect searches for Dark Matter in the Galaxy, under the hypothesis that the background from secondary astrophysical production is negligible. Constraining predictions for the secondary cosmic-ray flux of anti-helium and anti-deuteron with data is therefore crucial to the experimental searches. This contribution focuses on the impact of antimatter measurements at the Large Hadron Collider (LHC) on these searches. In proton-proton, proton-nucleus and nucleus-nucleus collisions at the TeV collision energy scale, light nuclei and their anti-matter counterparts are produced in equal amounts for a given species. The LHC can be used as “anti-matter factory” to measure the production of d_bar, 3He_bar and 4He_bar. In addition to providing unique information to characterise the system produced in high-energy collisions, accelerator data on anti-nuclei production can be used to constrain production models such as coalescence. The most recent results on anti-nuclei production at the LHC will be presented and implications for cosmic ray physics and indirect dark matter searches will be discussed.
Speaker: Dr Francesca Bellini (CERN)
• 17:00 19:20
Tuesday Afternoon Session
Convener: Dr Burkhard Kolb (GSI Darmstadt)
• 17:00
Search for a stable six-quark state in Upsilon decays 20m
Recently, it has been proposed that the six-quark combination uuddss could be a deeply bound state S, called the "sexaquark". Depending on its mass, S could have a lifetime longer than the age of the universe, or even be absolutely stable. This makes S a good Dark Matter candidate, if it exists. In this talk we present the first search for a stable, deeply-bound, doubly strange six-quark state in the decay Upsilon --> S Lambdabar Lambdabar, using a data sample of 90 M Upsilon(2S) and 110 M Upsilon(3S) decays collected by the BABAR experiment. No signal is observed, and upper limits on the combined Upsilon(nS) --> S Lambdabar Lambdabar branching fractions are derived, setting stringent limits on the existence of such an exotic particle. [Ref: BABAR Collaboration, Search for a Stable Six-Quark State at BABAR, arXiv:1810.04724, submitted to PRL]
Speaker: Prof. Wolfgang Gradl (Universität Mainz)
• 17:20
Double-folding potentials from local chiral EFT interactions 20m
We present the first determination of double-folding potentials based on chiral effective field theory up to next-to-next-to-leading order. To this end, we construct new two-body soft local chiral effective field theory interactions. We also present a first assessment of the impact of three-body interactions from chiral EFT on the nucleus-nucleus folding potential. We benchmark this approach in oxygen-oxygen scattering, and present results for cross sections computed for elastic scattering, as well as for the astrophysical S-factor of the fusion reaction.
Speaker: Ms Victoria Durant (TU Darmstadt)
• 17:40
Underground Nuclear Astrophysics: Present and future of the LUNA experiment 20m
Thermonuclear reaction rates regulate the evolution of stars and the Big Bang Nucleosynthesis. The LUNA Collaboration has shown that, by exploiting the ultra low background achievable deep underground, it is possible to study the relevant nuclear processes down to the nucleosynthesis energy inside stars and during the first minutes of Universe. In this presentation the main results of LUNA50 and LUNA 400 are overviewed, as well as the scientific program the forthcoming 3.5 MV underground accelerator that will be operative at the Gran Sasso laboratory in 2019.
Speaker: Dr Carlo Gustavino (INFN-Roma1)
• 18:00
Proton-Xi interaction studied via the femtoscopy method in p-Pb collisions measured by ALICE. 20m
Femtoscopic studies of Baryon-Baryon pairs opens a new era of studying twoparticle interactions at colliders. In particular, small collision systems prove to be particularly well suited to probe the short-ranged strong potentials. Experimental data are compared to local potentials with the newly developed Correlation Analysis Tool using the Schrödinger Equation (CATS). This analysis is based on the data measured by the ALICE Collaboration from pPb collisions at 5.02 TeV and the correlation function is obtained for pairs of protons and $\Xi$s. For the first time, an attractive strong interaction is observed between the two particles is observed with a significance of more than 3$\sigma$. Lattice calculations by the HAL QCD to model the latter are validated and are used to explore the implications of including the newly found attractive p-$\Xi$ interaction in the description of neutron stars.
Speaker: Mr Bernhard Hohlweger (PhD Student)
• 18:20
The Dose Profiler tracker: an online Particle Therapy monitor optimised for the detection of charged fragments produced by the ion beams interactions with matter. 20m
The use of C, He and O ions in Particle Therapy (PT) exploits the enhanced Relative Biological Effectiveness and Oxygen Enhancement Ratio of such projectiles to improve the treatment efficacy in damaging the cancerous cells. To fully profit from the increased tumor control probability and ballistic precision of the projectiles, an accurate online monitor of the dose release spatial distribution is required to spare the healthy tissues surrounding the tumor area, preventing unwanted damage due to, for example, morphological changes in the patient during treatment with respect to the initial CT scan. A monitoring technology capable of monitoring online PT treatments is still missing in the clinical routine. Several studies are underway to develop beam range verification systems exploiting the detection of the emitted secondary radiation produced by the primary beam interactions with the patient body along the path towards the target volume. An interesting opportunity for C, He and O treatments is represented by the detection of charged particles that can be performed with high efficiency in a nearly background free environment. The Dose Profiler (DP) detector, developed within the INSIDE project, is a scintillating fibre tracker that allows an online charged fragments reconstruction and backtracking. The unfolding of the different matter interaction effects (absorption and multiple scattering inside the patient) on the measured shape represent a crucial task when trying to correlate the measured emission profile with the beam range. Several strategies, based on MC methods, are currently being explored to accomplish such task. In this contribution the preliminary tests performed on the DP, using the $^{12}$C ions beam of the CNAO treatment centre and an anthropomorphic phantom (RANDO®) as target, will be reported together with the implications for the treatment monitoring applications. The first DP clinical trial is scheduled to start in early 2019 at the CNAO center aiming to study the fragments production in the treatment of patients with different clinical conditions and expected treatment toxicity.
Speaker: Ms Micol De Simoni (Università di Roma "La Sapienza", Scienze di Base e Applicate per l'Ingegneria, Rome, Italy)
• 18:40
Search for new decay modes in neutron-deficient silicon isotopes 20m
A characteristic feature of nuclei lying on the left of the $\beta$-stability path, extremely far away from it, is their high Q$_{\beta^+}$-value. This can result in the population of highly excited - and often unbound - states in the daughter nuclei. As a consequence, it can lead to $\beta$-delayed (multi-) charged-particle emission, being very competitive to deexcitation via $\gamma$ emission. Hence, studying of such decay channels is a unique tool for gaining an insight and understanding on the nuclear structure in this region. Moreover, such nuclei are often close to the path followed by the astrophysical rp-process [1,2]. The two most neutron-deficient silicon isotopes known, $^{22,23}$Si, were investigated in an experiment performed at the MARS spectrometer at the Cyclotron Institute, Texas A&M University. The ions were implanted into the Warsaw Optical Time Projection Chamber [3], which is an excellent tool for investigating rare decay modes with almost 100% detecting efficiency. The data collected allowed to confirm all known decay channels ($\beta$1p, $\beta$2p), as well as to identify convincing candidates for the new decay branches. The results of the analysis will be presented and discussed. [1] H. Schatz et al., Phys. Rep. 294, 167 (1998) [2] B.A. Brown et al., Phys. Rev. C 65, 045802 (2002) [3] M. Pomorski et al. Phys. Rev. C, 90, 014311 (2014)
Speaker: A. A. Ciemny (Faculty of Physics, University of Warsaw, Poland)
• Wednesday, 23 January
• 09:00 13:25
Wednesday Morning Session
Convener: Prof. John Harris (Yale University)
• 09:00
IceCube: Opening a Neutrino Window on the Universe from the South Pole 45m
IceCube: Opening a Neutrino Window on the Universe from the South Pole
Speaker: Prof. Francis Halzen (University of Wisconsin-Madison)
• 09:45
Neutron-star merger modelling after GW170817 45m
This overview talk will summarize the status of the numerical modelling of neutron-star mergers. The focus will be particularly on the role of neutrinos, which determine the composition of matter ejected during and after the neutron-star collision and thus the properties of the electromagnetic kilonova emission. A newly developed, computationally fast 'Improved Leakage-Equilibration-Absorption Scheme' (ILEAS) will be introduced. This new treatment allows for efficient simulations of large model grids, which is necessary to explore the high-dimensional space of merger parameters and conditions.
Speaker: Prof. Hans-Thomas Janka (Max Planck Institute for Astrophysics)
• 11:00
Experimental constraints from LHC on the Quark-Gluon Plasma 45m
An overview of recent results of the ALICE collaboration is given with emphasis on recent results from LHC run 2 and how they provide insight in the understanding of hot and dense nuclear matter. Particular attention is given to the observation of collective effects in small collision systems which have caused a paradigm shift in the field of heavy ions in the last years. An outlook is given to the upcoming decade of heavy-ion collisions at the LHC.
Speaker: Dr Jan Fiete Grosse-Oetringhaus (CERN)
• 11:45
Status and perspectives of the Belle II experiment. 35m
The Belle II experiment at the SuperKEKB e+e- collider has completed a commissioning phase in 2018 and is gearing up for full physics data taking starting in March 2019. In this paper the status of the experiment, the first results of the 2018 data taking, as well as the futures plans and perspectives will be presented.
Speaker: Prof. Francesco Forti (INFN and University, Pisa)
• 12:20
QCD phase diagram from Dyson-Schwinger equations 20m
We review results for the phase diagram of QCD, the properties of quarks and gluons and the resulting properties of strongly interacting matter at finite temperature and chemical potential. The interplay of two different but related transitions in QCD, chiral symmetry restoration and deconfinement, leads to a rich phenomenology when external parameters such as quark masses, volume, temperature and chemical potential are varied. We discuss the progress in this field from a theoretical perspective, focusing on non-perturbative QCD as encoded in the functional approach via Dyson-Schwinger and Bethe-Salpeter equations. We discuss various aspects associated with the variation of the quark masses, assess recent results for the QCD phase diagram including the location of a putative critical end-point for $N_f=2+1$ and $N_f=2+1+1$, discuss results for quark spectral functions and summarise aspects of QCD thermodynamics and fluctuations.
Speaker: Prof. Christian Fischer (JLU Giessen)
• 17:00 19:40
Wednesday Afternoon Session
Convener: Dr Harald Merkel (Institut für Kernphysik, Johannes Gutenberg-Universität Mainz)
• 17:00
Comparison of Transport Codes for Intermediate Energy Heavy Ion Collisions under Controlled Conditions 20m
Transport descriptions of heavy ion collisions in the intermediate energy range are an important method to extract information on the nuclear equation-of-state which is also relevant for astrophysical processes. Different transport model codes have been developed and applied widely. The physical deductions of such analyses should be independent as much as possible of the particular model, or at least, differences should be well understood. However, this has not always been the case in recent analyses, e.g. of pion production. In view of this a transport code evaluation project under controlled conditions with the participation of most of the widely used codes has been initiated some time ago to understand these differences. A first study was made for Au+Au collisions, which showed rather substantial differences. To investigate these further, comparisons were made of calculations in infinite nuclear matter, which can be realized in a good approximation in a box with periodic boundary conditions. In this set-up the different aspects of a transport calculation can be investigated separately and can be compared against analytical results. We have completed a study of the collision term, and found an important influence of the fluctuations, which are intrinsically built into the codes, e.g. on the Pauli-blocking behavior. Work on the mean field propagation and on pion production is in progress. In this talk I will give an overview of the status and conclusions of these comparisons and discuss implications on transport code development and future directions.
Speaker: Prof. Hermann Wolter (Univeristy of Munich)
• 17:20
Breaking and restoration of rotational symmetry in the low-energy spectrum of light alpha-conjugate nuclei on the lattice 20m
The breaking of rotational symmetry on the lattice for bound eigenstates of the two lightest alpha conjugate nuclei is explored. Moreover, a macroscopic alpha-cluster model is used for investigating the general problems associated with the representation of a physical many-body problem on a cubic lattice. In view of the descent from the 3D rotation group to the cubic group symmetry, the role of the squared total angular momentum operator in the classification of the lattice eigenstates in terms of SO(3) irreps is discussed. In particular, the behaviour of the average values of the latter operator, the Hamiltonian and the inter-particle distance as a function of lattice spacing and size is studied by considering the 0+, 2+, 4+ and 6+ (artificial) bound states of 8Be and the lowest 0+, 2+ and 3− multiplets of 12C. Some preliminary results of the analysis of the 16O spectrum, subject of an incoming paper, are going to be shortly presented.
Speaker: Mr Gianluca Stellin (Helmholtz Institut für Strahlen- und Kernphysik (HISKP) - Universität Bonn)
• 17:40
New Physics in Nuclear Collectivity – The Latest 20m
J. F. Sharpey-Schafer University of the Western Cape, Cape Town, South Africa Abstract Recent developments in the experimental data on “collective” structures at low excitation energies have challenged the traditional paradigms of the essential physics involved in the underlying configurations. The importance of systematic experimental studies, that vary the deformations and asymmetries of the mean nuclear shape, is stressed. The limitations of collective descriptions of nuclear structure are discussed, especially the limitations of “phonon” and “boson” approximations to describe both low energy excitations of “spherical” and deformed nuclei. The importance of axial asymmetry in quadrupole deformation is stressed and the importance of octupole deformations, in some regions of the nuclear chart, is vital to understanding the detailed nuclear structure. We will discuss whether the collective excitations at low excitation energies can be described entirely in terms of the mean nuclear shape of non-spherical nuclei and where real “vibrations” of nuclei might occur.
Speaker: Prof. John F. Sharpey-Schafer (University of the Western Cape)
• 18:00
Development of an accurate DWIA model of coherent pion photoproduction to study neutron skins in medium heavy nuclei 20m
Despite decades of studies which have seen the nuclear charge distribution being measured with increasing precision, the neutron distribution remains elusive. The difference between the neutron and proton distributions is often expressed as the difference of their root mean square radii: the neutron skin thickness. Recently, the A2 collaboration at MaMi has measured the skin thickness in lead [1]. This experiment was based on coherent pion photoproduction, where a photon impinges on a nucleus and produces a neutral pion coherently (the nucleus remains in its ground state). The pion is then measured through its two-photon decay by utilizing a large solid-angle photon detector, the Crystal Ball (CB) in conjunction with the Glasgow photon tagger. The coherent photoproduction measurements are thus very clean. At first order, in the plane wave impulse approximation (PWIA) in which the final state interaction between the outgoing pion and the nucleus is neglected, the photoproduction cross section is proportional to the nuclear density from factor. In combination with charge distribution measurements, coherent pion photoproduction is a good way of measuring the neutron skin thickness. However, the distortion caused by the final state interaction of the pion with the nucleus has a significant impact on these cross sections and induces model dependency. These are included in the distorted wave impulse approximation (DWIA). In this work, we develop a new reaction code in the DWIA to help the (still ongoing) analysis of recent measurements by the A2 collaboration at MaMi of the coherent pion photoproduction cross section on $^{116,120,124}$Sn isotopes. In this reaction code, we devise a new potential for the scattering of pion off $^{12}$C, based on the work of K. Stricker Bauer [2]. This potential is constructed from the partial wave analysis of pion scattering off free protons and neutrons in the SAID database [3]. It contains first and second order terms (the pion being scattered once or twice by the nucleons of the nucleus, respectively) and absorptive terms. The main interest of this potential is that it should be valid on a large range of energies with only minor adjustments and allows the use of realistic densities (for example at mean field approximation). This tight collaboration between the experimental and theoretical groups and this new reaction code will thus allow the study of the influence of details of neutron densities on the pion photoproduction cross sections by improving the quality of the potential used to simulate the final state interaction. \\ \\ {[1] C. Tarbert et al., Phys. Rev. Lett. 112, 242502 (2014)} \\ {[2] K. Stricker-Bauer, Ph.D. thesis, Michigan State University (1980)}\\ {[3] R. L. Workman at al., Phys. Rev. C 86, 035202 (2012)}
Speaker: Mr Frederic Colomer (ULB (Université Libre de Bruxelles))
• 18:20
Machine Learning based jet momentum reconstruction in heavy-ion collisions 20m
The precise reconstruction of jet transverse momenta in heavy-ion collisions is a challenging task. A major obstacle is the large number of (mainly) low-$p_\mathrm{T}$ particles overlaying the jets. Strong region-to-region fluctuations of this background complicate the jet measurement and lead to significant uncertainties. In this talk, a novel approach to correct jet momenta (or energies) for the underlying background in heavy-ion collisions will be presented for the first time. The proposed method was recently described in a paper submitted to PRC[1]. The analysis makes use of common Machine Learning techniques to estimate the jet transverse momentum based on several parameters, including properties of the jet constituents. Using a toy model and HIJING simulations, the performance of the new method is shown to be superior to the established standard area-based background estimator. The application of the new method to data promises the measurement of jets down to extremely low transverse momenta, unprecedented thus far in data on heavy-ion collisions. [1] preprint available at https://arxiv.org/abs/1810.06324
Speaker: Ruediger Haake (Yale University)
• 18:40
DarkMESA: Light dark matter search at the MESA beam-dump 20m
At the MESA accelerator in Mainz, Germany, the parasitic electron beam-dump experiment DarkMESA has a powerful discovery potential for dark sector particles in the light mass range. The possible existence of such light dark matter (LDM) is a candidate explanation for the long-standing dark matter problem. With 10 000 hours of operation time scheduled for P2 beam experiment at MESA, the dump of the external 150 $\mu$A beam could act as a strong source of a LDM beam. LDM would be produced copiously in the relativistic electron-nucleus collisions taking place in the dump if it couples to electrons via vector mediators, called dark photons. After production, LDM particles could be detected within a shielded detector down-stream of the dump. A large advantage is provided by the boost at which particles are produced by the beam, allowing an improved reach at low masses. Moreover, such a search is unique since it can probe at the same time both the dark photon production and the LDM interaction. DarkMESA will benefit from the beam energy being below pion production threshold, producing very little beam-related backgrounds, and the very stable and continuous beam conditions necessary for the P2 experiment. The DarkMESA detector will be constructed from total absorbing calorimeters made of high-density Cherenkov radiators. Advantages are their speed and relatively low sensitivity to background neutrons. In order to establish the anticipated performance of such calorimeters experimentally, measurements of detector responses over a range of electron energies relevant for LDM detection down to 5 MeV were performed. PbF$_2$ and SF5 lead glass detectors proofed to be well suited. The first phase of DarkMESA will employ available PbF$_2$ crystals for building a (1 x 1 x 0.13) m$^3$ detector of 1200 kg mass. This calorimeter will be arranged in sub-modules of 5 x 5 crystals. In a 2nd phase, additional calorimeters will be constructed from Pb glass blocks: a first prototype with a volume of 0.15 m$^3$ and a mass of 600 kg is already under construction. The completed Phase-2 calorimeters will comprise 1 m$^3$ volume and a mass of 4100 kg. A final active volume of above 10 m$^3$ is envisaged. Simulation studies were performed that explored the parameter space of possible dark photon masses and couplings, assuming realistic electron beam energy and angular distributions as well as different detector acceptances and efficiencies. They show that DarkMESA is complementary to experiments at proton beam facilities and reopens the door to regions of the parameter space excluded by searches for dark photon decays into electrons or muons. The studies indicate that DarkMESA has the potential to be sensitive to the LDM thermal relic targets, that are predicted by the annihilation cross sections for reproducing today's dark matter density.
Speaker: Prof. Patrick Achenbach (JGU Mainz)
• Thursday, 24 January
• 09:00 13:20
Thursday Morning Session
Convener: Prof. Marcel Merk (Nikhef)
• 09:00
Latest results from the ATLAS Experiment 45m
Latest results from the ATLAS Experiment
Speaker: Stan Lai (Universität Göttingen)
• 09:45
The DarkSide experiment. 45m
The DarkSide experiment.
Speaker: Prof. Cristiano Galbiati (Princeton University)
• 11:00
Exploring towards the neutron-rich limit of nuclei, and beyond 35m
How many neutrons can be added to a bound nucleus before it becomes unbound? The location of the neutron drip line, the bound limit in the neutron-rich side in nuclear chart, is indeed one of the fundamental unsolved questions in nuclear physics, as this is established experimentally only up to Z=8. The other question we address here is how atomic nuclei behave near the drip line and beyond. With these questions in mind, I present and discuss the recent experimental studies on exotic neutron rich nuclei,using the advanced rare-isotope in-flight beam facilities [1]. Neutron rich nuclei, in particular near and beyond the neutron-drip line, show characteristic structure due to the weakly-binding (or unbinding), and large difference between neutron and proton Fermi energies. Key aspects are the nuclear shell evolution, deformation, continuum effects, neutron halo, and the strong two neutron correlations called dineutron, which are discussed. Here, I will focus on the results on nuclei near/beyond the neutron drip line, using SAMURAI facility at RIBF, RIKEN. Finally, I will provide perspectives on experimental studies using the new-generation RI-beam facilities towards the neutron-rich limit of nuclear chart. [1] T.Nakamura, H. Sakurai, H. Wtanabe, Prog. Part. Nucl. Phys. 97, 53 (2017).
Speaker: Prof. Takashi Nakamura (Tokyo Institute of Technology)
• 11:35
Heavy ion and fixed target results at LHCb 30m
Heavy ion and fixed target results at LHCb
Speaker: GIULIA MANCA (UNIVERSITY OF CAGLIARI AND INFN)
• 12:05
Structure of light s-shell \Xi hypernuclei 30m
One of the important subject in hypernuclei is to extract information on hyperon-nucleon and hyperon-hyperon interactions. For two decades, by experimental and theoretical efforts, we could succeed in obtaining information on \Lambda N interaction. Then, as a next step, we focus on \Lambda \Lambda and \Xi N interactions. Especially, we have a lot of ambiguity of \Xi N interaction. In this meeting, I will report s-shell \Xi hypernuclei such as NN\Xi and NNN\Xi systems using Nijmegen potential and \Xi N potential based on HAL collaboration. In addition, I will explain how to extract information on \Xi N interaction from the calculation.
Speaker: Prof. EMIKO HIYAMA (Kyushu Univeristy/RIKEN)
• 17:00 19:30
Thursday Afternoon Session
Convener: Prof. Christian Fischer (JLU Giessen)
• 17:20
The fastest Time Projection Chamber of the world 20m
The upgrade of the ALICE Time Projection Chamber (TPC) is an essential part of the experiment's preparation for the LHC Run 3 starting in 2021. The production of the new readout detectors has been practically completed; the detectors will be installed in the TPC in a few months from now. The Gas Electron Multiplier technology, on which they are based, will enable us to operate the TPC in a continuous mode, sampling the full rate of lead-lead collisions offered by the LHC. In my presentation I will briefly describe the design and production of the chambers, and review the physics prospects opening in Run 3.
Speaker: Dariusz Miskowiec (GSI)
• 17:40
Local equilibration of fermions and bosons 20m
It is proposed to model the local kinetic equilibration in finite systems of fermions and bosons based on a nonlinear diffusion equation [1,2]. It properly accounts for their quantum-statistical characteristics, and is solved exactly. The solution is suited to replace the linear relaxation ansatz that has often been used in the literature. The microscopic transport coefficients are determined through the macroscopic variables temperature and local equilibration time. The model can be applied to high energies typical for relativistic particle collisions, and to low energies appropriate for cold quantum gases. With initial conditions that are appropriate for quarks [1] and gluons [2] in a relativistic heavy-ion collision such as Au-Au or Pb-Pb at energies reached at RHIC or LHC, the analytical solution is derived. It agrees with the numerical solution of the nonlinear equation. The analytical expression  for the gluonic local equilibration time in the thermal tail is compared to the corresponding case for fermions, where Pauli’s principle delays the thermalisation. Due to the nonlinearity of the basic equation, sharp edges of the initial distributions are continously smeared out and local equilibrium with a thermal tail in the ultraviolett region is rapidly attained [2]. [1] G. Wolschin, Phys. Rev. Lett. 48, 1004 (1982); T. Bartsch, G. Wolschin, Annals Phys., in press, and arXiv:1806.04044 (2018). [2] G. Wolschin, Physica A 499,1 (2018); Europhys. Lett. 123, 20009 (2018).
Speaker: Prof. Georg Wolschin (U Heidelberg)
• 18:00
Probing the structure of weak interactions 20m
The Standard Model as a very succesful theory of electroweak interactions postulates the basic assumption about the pure "V(ector)-A(xial vector)" character of the interaction. Nevertheless, even after more than half a century of development of the model and experimental testing of its fundamental ingredients, experimental data still rule out the existence of other types of weak interactions (scalar, tensor) only at the ~8% level. A new project at ISOLDE/CERN to search for these forbidden components of weak interactions (or at least significantly improve their current experimental limits) WISARD is being prepared. Experimental setup WISARD online on the beam of isotope separator ISOLDE plans to probe the existence of scalar currents in the weak interactions via the study of β-delayed protons emitted in the decay of 32Ar. High precision measurement of the Doppler effect on the protons emitted from the moving recoil nuclei after the β –decay of 32Ar carries information about β- angular correlations (different for a scalar current compared to the dominant vector current). Current status of the WISARD setup and first results of the commissioning runs will be presented.
Speaker: Dalibor Zakoucky (Nuclear Physics Institute of ASCR)
• 18:20
Overview of recent measurements of Upsilon production and suppression with the STAR experiment 20m
$\Upsilon$ states can be used to study the properties of the quark-gluon plasma created in heavy-ion collisions. At sufficiently high temperature, $\Upsilon$ mesons dissociate in the plasma as a result of the Debye-like screening of the strong force. Due to their different binding energies, the ground and excited $\Upsilon$ states are expected to dissociate in a sequential pattern. However, other effects, such as the influence of Cold Nuclear Matter (CNM), need to be taken into account when interpreting the $\Upsilon$ suppression observed in heavy-ion collisions. Furthermore, the quarkonium production mechanism in elementary collisions is not yet fully understood. This can be studied by comparing experimental measurements of $\Upsilon$ production in p+p collisions to theoretical calculations. In addition, the dependence of the $\Upsilon$ yield on charged particle multiplicity can be used to study the interplay between hard and soft processes. In this talk, we will present recent $\Upsilon$ measurements with the STAR experiment. The $\Upsilon$ transverse momentum and rapidity spectra in $500\:\mathrm{GeV}$ p+p collisions will be compared to model calculations. In addition, the normalized $\Upsilon$ yield vs. normalized charged particle multiplicity will be presented and compared to results from other experiments and models. The nuclear modification factors for $\Upsilon(1S)$ and $\Upsilon(2S+3S)$ in Au+Au collisions as functions of centrality and transverse momentum will be shown and compared to LHC measurements. Also, the nuclear modification factor of $\Upsilon(1S+2S+3S)$ as a function of rapidity measured in p+Au collisions will be presented for quantifying the CNM effects.
Speaker: Dr Leszek Kosarzewski (Czech Technical University in Prague)
• 18:40
In-medium properties of Λ in π− - Induced Reactions at 1.7 GeV/c 20m
The high precision measurement of a two solar mass neutron star, gives a strong constrain to the equation of state (EOS) of several models describing such dense objects. While more data and recent experimental observations reduce the allowed phase space, the appearance of hyperons inside the neutron star core is still a discussed scenario. For all these EOS the interaction of the hyperon with (normal) nuclear matter is the key ingredient. Of particular interest is thus the $\Lambda$ hyperon, which should appear first, as it is the lightest hyperon. The Lambda-p interaction is known to certain extend and the existence of hypernuclei demonstrates the attractive nature of the lambda-nucleus interaction, no differential study of the Lambda propagation within nuclear matter was carried out so far. In 2014 the HADES collaboration measured $\pi^- + A$ ( A = C, W) reactions at an incident pion momentum of 1.7 GeV/c. Since the pion-nucleon cross section is rather larger, the hyperon production occurs at the surface of the nuclei for pion induced reactions . This provides an ideal system, as the path length of the produced hyperons through nuclear matter is rather large and hence in-medium properties can be studied. In our experimental approach we are selecting the exclusive channel of $\pi^-+p \rightarrow \Lambda + K^0$ reconstructed in term of their associated dominant charged decay products in an light (C) and heavy (W) nuclear environment. With the help of the GiBUU transport code, we are able to test different scenarios, which include different couplings of the $\Lambda$ to normal nuclear environment in combination with the $K^0$. One of this scenario also includes for the first time an repulsive $\Sigma^0$ potential, predicted by $\chi$-effective theory. We will report on the on-going analysis and present our sensitivity on the different scenarios of the in-medium propagation.
Speaker: Mr Steffen Maurus (TUM)
• Friday, 25 January
• 09:00 12:30
Friday Morning Session
Convener: Dr Mariana Nanova (II. Pays. Institut, University of Giessen, Giessen, Germany)
• 09:00
Novel silicon pixel detectors 45m
Novel silicon pixel detectors
Speaker: Dr Luciano Musa (CERN)
• 09:45
What it takes to calculate the magnetic moment of the muon in the standard model 35m
The magnetic moment of the muon is the observable which shows at the moment the largest discrepancy between experiment and standard-model prediction (3 to 4 standard deviations) [1]. To turn the indication to an observation requires the reduction of both experimental and standard-model uncertainty. The dominant source of the latter resides in the hadronic contributions that enter the magnetic moment via loop corrections that involve strongly interacting fields. At the present level of accuracy the main players are the hadronic vacuum polarization and the hadronic light-by-light (HLbL) scattering contribution. I will report how dispersion theory can be used to relate the hadronic contributions to measurable quantities and obtain in that way a data driven determination including a reliable uncertainty estimate. In particular, I will focus on the most recent determination of the leading contribution to HLbL emerging from the pion-pole diagram [2,3]. [1] F. Jegerlehner and A. Nyffeler, Phys. Rept. 477, 1 (2009) [2] M. Hoferichter, B. L. Hoid, B. Kubis, S. Leupold and S. P. Schneider, Phys. Rev. Lett. 121, 112002 (2018) [3] M. Hoferichter, B. L. Hoid, B. Kubis, S. Leupold and S. P. Schneider, JHEP 1810, 141 (2018)
Speaker: Stefan Leupold (Uppsala University)
• 10:50
Importance of the Tensor Interaction in Structure of Nuclei 35m
Studies of nuclei far from the stability line revealed drastic changes in nuclear orbitals presented as appearance of new magic numbers and disappearance of magic numbers. One of the important reason of such change is considered to be due to the effect of tensor forces in nuclear structure. Although the importance of tensor forces has been known as giving most of the binding energies in very light nuclei such as deuteron and 4He, direct experimental evidences of the importance in nuclear structure are scarce. In particular it is known that the mixing of higher waves, for example a D wave component in deuteron wave function with high-momentum component, is very important for the binding. Recent study of (p,d) and (p,pd) reaction at high momentum transfer will be presented and the importance of tensor interactions in low excited states of nuclei will be discussed.
Speaker: Prof. Isao Tanihata (RCNP, Osaka University)
• 11:25
Searching for a matter creating process in nuclear decays 35m
Searching for a matter creating process in nuclear decays
Speaker: Prof. Stefan Schoenert (TUM)
• 12:00
Indirect techniques in nuclear astrophysics 30m
Indirect techniques in nuclear astrophysics
Speaker: Prof. Aurora Tumino (Kore University, Enna &amp; INFN-Laboratori Nazionali del Sud, Catania)
• 17:00 19:30
Friday Afternoon Session
Convener: Prof. John Sharpey-Schafer (The University of the Western Cape, South Africa)
• 17:00
Neutron flows and neutron stars 20m
The nuclear symmetry energy at high density has been probed with heavy ion reactions at high energy and by analyzing neutron star properties. A new source of information has opened up with the observation of the first LIGO and Virgo GW170817 gravitational wave signal from a neutron star merger. It offers additional possibilities for quantitatively comparing terrestrial and celestial results with implications for the applied models and methods. The prospects for improved measurements of neutron and proton elliptic flows at FAIR using the NeuLAND and KRAB detectors will be discussed.
Speaker: Prof. Wolfgang Trautmann (GSI Helmholtzzentrum für Schwerionenforschung GmbH)
• 17:20
Internal Gas-Jet Target for high intensity electron beam experiments 20m
In the last three years a new target system has been developed in Mainz, which is dedicated to be the target of the upcoming MAGIX experiement. This target is a so called Gas-Jet Target, which is completele windowless. Therefore it should minimize uncertainities wich are typically induced by target frames and windows. To test this target a measurement @A1 in Mainz has been performed. This talk is about the target technique and the resuts of the measurements.
Speaker: Stephan Aulenbacher (JGU Mainz)
• 17:40
A versatile plastic neutron spectrometre for nuclear reactions and applications 20m
With the advent of the new facility for radioactive ion beams, in particular for the neutron rich ones with respect to the stable beams, it is necessary to develop neutron detection systems fully integrated with the charged particles detection. It is argued that, the integration of the neutron signal, especially for neutron reach beams is an important experimental progress in order to study the properties of exotic nuclear matter. Neutrons detection with high angular and energy resolution is also an important issue in many physical applications. For this reasons, new detectors using new material have to be built. In this contribution the NArCoS (Neutron Array for Correlation Studies) project, having the purpose to realize a new detector prototype for neutrons and charged particles, will be presented with particular emphasis to physical motivations and first experimental tests.
Speaker: Dr Emanuele Vincenzo Pagano (LNS-INFN)
• 18:00
Dalitz decays of hyperons studied by HADES detector 20m
Spectrum of excited states of single and double strange hyperons is only poorly known. Their internal structure is controversially discussed within several models e.g. quark and bag models, or even pentaquarks or meson-bayrion molecules like the famous $\Lambda$(1405). One of the kays to hyperons electromagnetic stucture are form factors which are predicted to be an ideal tool to discriminate between various models. The space-like region for transition form-fatctors have been already measured by the CLAS collaboration. The Hades detector is a perfect tool to perform similar research in the time-like region. The HADES detector is a versatile detector specialized for dilepton and strangeness measurements at SIS18 energies. It has been recently updated by an electromagnetic calorimeter, a new RICH photon detector. In next year an additional forward detector will be installed. It will extend an acceptance for forward peaked hyperons decays. All of this together, with improved SIS18 operating with protons at maximum energy 4.5 GeV, opens up new experimental possibilities. In my contribution I would like to present a feasibility studies for new experiments at 4.5 GeV beam kinetic energy in terms of excited hyperons Dalitz decays with use of the forward detector. Additionally a ongoing analysis of an existing data from pp@3.5 GeV and pNb@3.5 GeV experiments could give a predictions for count rates and production cross-sections.
Speaker: Mr Krzysztof Nowakowski (Jagiellonian University)
• 18:20
Determination of the $^4$He monopole transition form factor 20m
We will give an overview about new results for the $^4$He monopole transition form factor from data, taken in an electron scattering experiment at Mainz in 2016. Emphasis will be on different models for background contributions and the monopole resonance itself. On the sideline, we discuss the intrinsic FWHM (full-width-at-half-maximum) of the monopole resonance.
Speaker: Mr Simon Kegel (Institut fuer Kernphysik Uni Mainz)
• 18:40