54. International Winter Meeting on Nuclear Physics

25 Jan 2016, 07:30 → 29 Jan 2016, 20:00 Europe/Berlin

Bormio, Italy

Concettina Sfienti (Johannes Gutenberg-Universität Mainz), Laura Fabbietti (excellence cluster 'universe'), Wolfgang Kuehn (JLU Giessen)

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.

Monday 25 January

07:30 → 09:00 Pre-Conference School

The pre-conference school took place on sunday from 9:00 to 18:00.

07:30 Basic Topic in Hadron Physics

Speaker: Prof. Concettina Sfienti (Johannes Gutenberg-Universität Mainz)

Slides HadronPhysics-Bormio2016.pdf

07:50 Lecture Heavy Ion Preschool

Speaker: Prof. Laura Fabbietti (TUM)

Slides Intro_Laura.pdf

08:10 Basic Topic in Nuclear Structure and Astrophysics

Speaker: Dr Pierre Capel (Université Libre de Bruxelles (ULB))

Slides CapelAstroBormio16.pdf CapelNuclearPhysicsBormio16.pdf

08:30 Basic topics in Flavour Physics

Speaker: Prof. Wolfgang Kuehn (JLU Giessen)

Slides FlavourPhysics.pdf

09:00 → 13:00 Monday Morning

09:00 Beyond the Higgs Boson

No abstract delivered

Speaker: Prof. Matthias Neubert (JGU-Mainz)

Slides Neubert_Bormio.pdf

09:45 Replacing hydrodynamic simulations with transport theory

Hydrodynamic simulations have been pillars of nuclear theory for several decades. Here we will show that we can construct transport theories that capture all of the hydro features in the limit of very short mean free path, but also are applicable for large mean free path scenarios, in which hydro fails. We will solve a series of standard hydrodynamics test cases and also who that we can simulate instabilities of the Rayleigh-Taylor and Kelvin-Helmholtz types.

Speaker: Prof. Wolfgang Bauer (MSU)

Slides 2016_Bormio.pdf

10:30 Coffee Break

11:00 The Fukushima-Daiichi Nuclear Power Plant Accident

No abstract delivered

Speaker: Prof. Ryugo Hayano (Tokyo University)

Slides 2016.01.25_Bormio-hayano.pdf

11:45 Highlights on BESIII results

With the huge amount of data collected with BESIII detector at different center of mass energies, recently significant progresses on the study of XYZ states, light hadron spectroscopy and charm decays were achieved. In this talk, the most recent results from BESIII will be presented.

Speaker: Prof. Wolfgang Gradl (Mainz University)

Slides besiii-highlights.pdf

17:00 → 20:27 Monday Afternoon

17:00 Measurement of the proton form factor at very low Q^2

The proton is a basic constituent of matter, but its fundamental properties like the radius are, in spite of all effort, still not understood properly. The measurements of the radius via interaction with electrons or muons yield significantly different results, leading to the so called proton radius puzzle. To bring new insight into the observed discrepancy a new electron scattering experiment at Mainz Microtron has been performed using a measuring technique based on initial state radiation. The aim was to determine the charge form factor of the proton with percent precision at Q^2 as low as 3*10^(-4)(GeV/c)^2 , and obtaining a new value of the proton charge radius. The poster will offer a brief introduction to the radius problem as well as the underlying theory and overview of the experiment. The present status of the analysis and preliminary results will also be shown.

Speaker: Mr Adrian Weber (Institut für Kernphysik, Johannes-Gutenberg-Universität Mainz)

Slides Presentation.pdf

17:03 Extension of the ratio method to low energy

The ratio method is a recent observable that has been proposed for the study of halo nuclei [1]. It consists of the ratio of breakup angular distribution and the summed angu- lar distribution (which includes elastic, inelastic and breakup) and removes the reaction model dependence. Originally, this method was developed for high and intermediate ener- gies and studies of the reactions of 11 Be halo nucleus on 12 C and 208 Pb targets at 70 MeV/u have shown this observable to provide precise information about the halo structure [2]. Given the potential interest in applying this method at lower energy, we explore its validity at beam energies of 20MeV/u in this work. We use the Continuum Discretized Coupled Channel method and the Coulomb-corrected Dynamical Eikonal Approximation for the study of the reactions of 11 Be on 12 C, 40 Ca and 208 Pb at 20MeV/u. We compare the various theoretical descriptions and explore the dependence of our results on the core-target interaction. Our study demonstrates that the ratio method is still valid at these lower beam energies [3]. This could open up the way to its experimental testing in ISOL-type laboratories. [1] P. Capel, R. C. Johnson, and F. M. Nunes, Phys. Lett. B705, 112 (2011). [2] P. Capel, R. C. Johnson, and F. M. Nunes, Phys. Rev. C 88, 044602 (2013). [3] F. Colomer, P. Capel, and F. M. Nunes, in preparation.

Speaker: Mr Frederic Colomer (ULB (Université Libre de Bruxelles))

Slides 2-Colomer.pdf

17:06 Study of Improved $K_S^0$ Detection for the Belle~II Detector

In the near future, the Belle~II experiment at the SuperKEKB accelerator at KEK in Tsukuba, Japan, will start operation at a luminosity a factor $40$ higher than its predecessor experiment, Belle. The physics program includes the search for physics beyond the Standard Model of particle physics by the investigation of $CP$ violating processes and rare $B$ meson decays. Many important decay channels involve $K_S^0$ mesons. The detector features two layers of silicon pixel cells closest to the interaction point surrounded by four layers of double sided silicon strip detectors. Due to the high backgoround level, the expected occupancy of the Pixel Detector reaches up to $3\,\%$ requiring an online data reduction system: Using the four layers of strip detectors and the surrounding detectors, the online reconstructed tracks of charged particles are extrapolated to the pixelated layers, where Regions of Interest (ROIs) are defined around the intercepts. Only the pixel data inside these ROIs are stored. Thus, particles creating an insufficient number of hits in the outer detectors are not reconstructed and subsequntly no regions of interest are created, resulting in the loss of the related hits in the Pixel Detector. The particles creating a sufficient number of hits in all six layers, but not in the outer four, are lost as well. In this contribution, an online tracking algorithm is presented focusing on the reconstruction of charged pions from displaced vertices, the characteristic decay topology of $K_S^0$ mesons. All six layers are used, in order to prevent the pixel data of the above mentioned particles to be lost. The algorithm is based on the fast Hough transform applied to the hits mapped onto the conformal plane. The amount of background is reduced by a two stage neural network filtering system.

Speaker: Mr Leonard Koch (JLU Giessen)

Slides 3-koch.pdf

17:09 Progresses on Light hadron spectroscopy

The BESIII experiment at the electron positron collider BEPCII in Beijing is successfully operating since 2008 and has collected large data samples in the tau-mass region, including the world’s largest data samples at the J/psi and psi’ resonances. In particular decays of these two resonances provide a rich and clean environment to study hadrons consisting out of light quarks and search for exotics. The collaboration has recently started a campaign to understand the nature of the X(1835) and Y(2175) resonances, which are debated to be exotic matter. Important observations have also been archived in baryon spectroscopy, where the analyses benefit from the well defined initial state in e+e- collisions. Further, decays of eta’ mesons are studied to deepen our knowledge of their structure and possible symmetry breaking effects in their decays. In this presentation recent results of the light hadron physics program will be highlighted.

Speaker: Mr Giulio Mezzadri (INFN Ferrara)

Slides 4-Mezzadri.pdf

17:12 Analysis of He-4 Inclusive Electron-Scattering-Experiments

Electron-Scattering-Experiments offer a deep insight into nuclear structure. While elastic Electron-Scattering is a technique used to determine the charge-radius of nuclei, the study of resonances or excited states can be used to test effective-field theories in a perturbative frame. Especially in the last years further progress was made in this field by performance of ab-initio calculations with respect to 3- and/or 4-body terms included. First results of the analysis of a former electron-scattering experiments from 2009 at MAMI of the A1 collaboration will be presented in this session.

Speaker: Mr Simon Kegel (Institut fuer Kernphysik Uni Mainz)

Slides 5-Kegel.pdf

17:15 Modelling Early Stages of Relativistic Heavy Ion Collisions: Coupling Relativistic Transport Theory to Decaying Color-Electric Flux Tubes

In this study we model early times dynamics of relativistic heavy ion collisions by an initial color electric field which then decays to a plasma by the Schwinger mechanism, coupling the dynamical evolution of the initial color field to the dynamics of the many particles system produced by the decay. The latter is described by relativistic kinetic theory in which we fix the ratio $eta/s$ rather than insisting on specific microscopic processes, and the backreaction on the color field is taken into account by solving self-consistently the kinetic and the field equations. Within a single self-consistent calculation scheme we address the problems of isotropization and thermalization of the quark-gluon plasma produced by the field decay, as well as the quark-gluon plasma formation time and its chemical equilibration, both for 1+1D and 3+1D expanding geometry. We find that regardless of the viscosity of the produced plasma, longitudinal pressure becomes positive within 0.2 fm/c. The initial color electric field decays within 1 fm/c; however in the case $eta/s$ is large plasma oscillations appear and affect the entire time evolution of the system. In case of small $eta/s$ ($eta/s$<0.3) we find that the isotropization time is approx. 0.8 fm/c and the thermalization time is approx. 1 fm/c. Moreover quark-gluon plasma production occurs in less than 1 fm/c, and almost perfect chemical equilibration takes place within 1 fm/c. Hence our work supports the common assumptions of hydrodynamics about thermalization, isotropization and equilibration of quark-gluon plasma.

Speaker: Mrs Lucia Oliva (INFN-Laboratori Nazionali del Sud, University of Catania)

Slides OLIVA_-_Modelling_early_times_dynamics_of_rhics.pdf

17:18 Forward production of neutrons in fragmentation of high energy heavy nuclei

The picosecond pulse of quasi-monoenergetic high-energy neutrons is produced in each interaction of relativistic heavy nuclei in light target. The energy and angular distributions of the neutrons for Pb + 1H and Pb + C collisions are estimated using Lorentz transformation of a Moving Source Model fit to the neutron data for reactions p + Pb and C + Pb at GeV energies. The analysis of neutron characteristics and energy resolution as a function of beam energy is given. This phenomenon may be used for generation of neutron beam at SPS energies at CERN and also it leads to formation of parasitic neutron beam in interactions of heavy ions with beam line materials. The last effect must be taken into account in a design of accelerator beam lines and shielding, experimental setups and forward detectors.

Speaker: Prof. Vladimir Yurevich (Joint Institute for Nuclear Research)

Slides 7-Yurevich.pdf

17:21 Computing for the LHC: operations during Run2 and getting ready for Run 3

The computing infrastructure for the LHC data handling (Worldwide LHC Computing Grid - WLCG) was well prepared for Run2 and delivered a steady data processing since the first collisions. Over the past years including the Run1 period of the LHC the WLCG developed a unique expertise in building and operating a very large scale infrastructure for unprecedented amounts of LHC-produced data. Together with other research projects the WLCG entered the era of Data Intensive Science. The cost of computing infrastructures and services reached the level needed for building the LHC detectors. In this contribution, we will present ongoing and planned developments to evolve the computing models towards the needs for the High Luminosity (HL) LHC, including the disappearance of the distinction between “online” and “offline”, analyses of the physics performance and corresponding computing costs, and inter-operation between commercial cloud services and publicly funded e-infrastructures.

Speaker: Dr Dagmar Adamova (Nuclear Physics Institute AS CR)

Poster ADAMOVA.POSTER.2016.9-tmp-2.x.pdf

Slides ADAMOVA.COMPUTING.SLIDES.2016.2-tmp-3.ppt

17:24 Performance of the ALICE secondary vertex b-tagging algorithm

Hard partons produced in the early stage of high-energy heavy-ion collisions suffer energy loss in the Quark-Gluon Plasma (QGP) via gluon radiation and elastic collisions while propagating through this medium. Jet reconstruction provides access to the kinematics of these partons. Reconstructed jets are therefore powerful tools to study the properties of the QGP. Theoretical models predict a dependence of the parton energy loss in the QGP on the color charge and the mass of the parton. Thus, the study of properties of beauty jets in comparison with that of light-flavour jets can reveal important information about the matter formed. Beauty-tagging algorithms rely on the properties of B hadrons, i.e. their long lifetime, large mass and large multiplicity of decay products. In this poster the b-tagging algorithm based on displaced secondary vertex topologies in p-Pb collisions with ALICE is described. We present Monte Carlo performance studies of the algorithm for reconstructed charged jets. The tagging efficiency, rejection rate and the correction of the smearing effects for the detector response are presented. Finally, the performance expected in LHC Run 3 is briefly discussed.

Speaker: Mr Lukas Kramarik (Czech Technical University in Prague)

Slides lukas_prez_bormio_v1.pdf

17:27 K- multi-nucleon absorption processes in hadronic interaction studies by AMADEUS

The recent hyperon-nucleon/nuclei correlation studies performed by the AMADEUS collaboration might reveal unprecedent informations on the K- low-energy interaction with light nuclei thanks to the unique kaon beam provided by the DAFNE collider and the excellent features of the KLOE detector. The Lp and the S0p final states, produced in the K- absorption processes on 12C and 4He, were analyzed. The excellent acceptance and resolution (for both charged particles and photons) enabled to provide informations for a wide range of the allowed kinematic regions, and to disentangle single from multi-nucleon K- absorption processes. A yield of K-pp/K-stop = (0.044 ± 0.009 stat +0.004-0.005 syst) 10-2 was extracted for a ppK- bound state, decaying in S0p, characterized by a binding energy and a width of 45 and 30 MeV/c2 respectively. A statistical analysis was performed revealing that the bound state is only significant at the level of 1s.

Speaker: Raffaele Del Grande (INFN-LNF)

Slides 10-Del_Grande.pdf

17:30 XYZ studies at BESIII

The BESIII Experiment collected large data samples for electron-positron collisions with center-of-mass above 4 GeV during 2013 and 2014. The analysis of these samples has resulted in a number of surprising discoveries, such as the discoveries of the electrically charged 'Zc' structures, which, if resonant, cannot be accomodated in the traditional charm quark and anti-charm quark picture of charmonium. In this talk, we will review the current status of the analyses of the Zc structures, as well as a number of other interesting features in the new BESIII data samples.

Speaker: Mr Gianfranco Morello (LNF)

Slides 11-Morello.pdf

17:33 The RUN-2 ATLAS Trigger System

The ATLAS trigger has been successfully collecting collision data during the first run of the LHC between 2009-2013 at a centre-of-mass energy between 900 GeV and 8 TeV. The trigger system consists of a hardware Level-1 (L1) and a software based high-level trigger (HLT) that reduces the event rate from the design bunch-crossing rate of 40 MHz to an average recording rate of a few hundred Hz. In Run-2, the LHC will operate at centre-of-mass energies of 13 and 14 TeV resulting in roughly five times higher trigger rates. We will briefly review the ATLAS trigger system upgrades that were implemented during the shutdown, allowing us to cope with the increased trigger rates while maintaining or even improving our efficiency to select relevant physics processes. This includes changes to the L1 calorimeter and muon trigger systems, the introduction of a new L1 topological trigger module and the merging of the previously two-level HLT system into a single event filter farm. At hand of a few examples, we will show the impressive performance improvements in the HLT trigger algorithms used to identify leptons, hadrons and global event quantities like missing transverse energy. Finally, we will present the commissioning of the trigger system and its performance from the 2015 run.

Speaker: Mrs Savanna Marie Shaw (CERN)

Slides 12-sshaw.pdf

17:36 PANDA Forward Spectrometer Calorimeter

PANDA Forward Spectrometer Calorimeter The PANDA experiment is one of the challenging projects being constructed on new FAIR facility near Darmstadt. It will use the antiproton beam from the High Energy Storage Ring colliding with an internal proton target and a general purpose spectrometer to carry out a rich and diversified hadrons physics program. One of the main PANDA detectors is a calorimeter complex consisting of a central PWO crystal based calorimeter and a forward shashlyk-type sampling calorimeter. The design of the PANDA Forward Spectrometer Calorimeter (FSC) is completed and validated by several test-beam measurements. The FSC prototype performance based on test-beam measurements at Protvino and Mainz will be presented in the report. The construction of the PANDA detector has been started and planned to be completed before 2019. FSC Technical Design Report recently was submitted to FAIR experts committee and construction of the detector is expected to be started in the next year. The detector production-ready status including mass-production techniques developed at IHEP, Protvino is also presented in the report.

Speaker: Dr Pavel Semenov (IHEP Protvino)

Slides bormio2016_short.ppt bormio2016_short_1.pdf

17:39 Study of the 2H(p,γ)3He reaction in the BBN energy range at LUNA

The Big Bang Nucleosynthesis (BBN) describes the production of light nuclides in the first minutes of cosmic time. It started with deuterium accumulation when the Universe was cold enough to allow 2H nuclei to be survived to photo-disintegration. A primordial deuterium abundance evaluation D/H=(2.65±0.07)×10^(-5) [1] is obtained by merging BBN calculations and CMB analysis obtained by the Planck collaboration. This value is in tension with the astronomical observations on metal-poor damped Lyman alpha systems, according to which D/H=(2.53±0.04)×10^(-5) [2]. The main source of uncertainty on standard BBN prediction of deuterium abundance is actually due to the radiative capture process 2H(p,γ)3He converting deuterium into helium, because of the poor knowledge of its S-factor at BBN energies. A measurement of this reaction cross section is thus desirable with a 3% accuracy in the energy range 10keV<Ecm<300keV [1]. Furthermore a precise measurement of the p+d reaction cross section is crucial for testing ab-initio calculations in theoretical nuclear physics. Thanks to the low background of the underground Gran Sasso Laboratories (LNGS) and to the experience accumulated in more than twenty years of scientific activity, LUNA (Laboratory for Underground Nuclear Astrophysics) [3][4] has planned to measure the 2H(p,γ)3He fusion cross section in the energy range of interest in 2016. The experimental procedure for studying this reaction consists of two main phases characterized by two different set up. The former provides for a windowless gas target filled with deuterium at 0.3mbar pressure together with a 4π BGO detector. This high efficiency detector will be used for investigating the energy range between 30keV and 260keV, trying to find a continuation of the previous results obtained by the LUNA collaboration in [5], where the 2H(p,γ)3He cross section was studied in the Solar Gamow peak (2.5keV<Ecm<22keV). The latter phase, instead, will cover the medium-high energies (70keV<Ecm<260keV) using a High Purity Germanium detector (HPGe). The HPGe high resolution allows the differential cross section of the reaction to be evaluated by using the peak shape analysis. The aim of the present work is to describe the two experimental set up that will be used in the measurement campaign. Possible cosmological and theoretical nuclear physics outcomes from the future LUNA data will be also discussed. REFERENCES: [1] E. Di Valentino et al., Phys. Rev. D 90 (2014) 023543 [2] R. Cooke at al., Astrophys. J. 781 (2014) 31 [3] H. Costatini et al., Rep. Prog. Phys. 72 (2009) 086301 [4] C. Broggini et al., Ann. Rev. Nucl. Part. Sci. 60 (2010) 53 [5] C. Casella et al., Nucl. Phys.,A 706 (2002) 203

Speaker: Dr Viviana Mossa (INFN sez. di Bari - Università degli studi di Bari)

Slides 14-Mossa.pdf

17:42 Electron Identification and Hadron Contamination Studies in Proton-Proton Collisions with ALICE

The continuum of electron-positron pairs, produced in heavy ion collisions, provides an excellent probe of the quark-gluon plasma. To extract possible signatures, it is important to work with an electron sample of high purity. Dielectrons are also studied in proton-proton collisions to provide a crucial reference. This poster presents an analysis performed on a data set of pp collisions at √s = 7 TeV measured with the ALICE detector at the Large Hadron Collider. The aim of the work is to optimize the electron identification and to reduce the hadron contamination. For that, invariant mass spectra of electronpositron pairs based on three different PID sets are compared and the hadron contamination of the dielectron sample is estimated as a function of invariant mass. The analysis shows that one can achieve good electron identification efficiencies and a single electron purity higher than 90% by combining the signals of the ITS, TPC and TOF detectors in ALICE

Speaker: Mrs Anisa Dashi (TUM)

Slides 15-ADashi.pdf

17:44 study of the eta meson production with polarised proton beam

The eta meson production process can be studied via measurements of the analyzing power, Ay, which may be understood as a measure of the relative deviation between the dierential cross section with and without polarized beam. Spin-dependent observables such as cross sections and analyzing powers have been determined only for a small number of excess energies and with very high statistical uncertainty. Therefore, measurements of the reaction ~pp ! pp was performed at the WASA-at-COSY detector in a xed-target experiment with beam momenta of 2026 MeV/c and 2188 MeV/c. These correspond to excess energies of 15 MeV and 72 MeV, respectively. The meson was identied by the techniques of missing mass and invariant mass. The invariant mass technique was mainly used to reduce background events, while the missing mass technique provided accurate kinematics of the meson. The experimental angular distribution of the analyzing power will be compared to the theoretical predictions and they will be interpreted in view of the contribution of higher partial waves. 1

Speaker: Mrs Iryna Schätti-Ozerianska (Jagiellonian Univ)

Slides 16-Schaetti.pdf

18:30 Posters Discussion

Tuesday 26 January

09:00 → 13:15 Tuesday Morning

09:00 Recent results of the ALICE experiment

no abstract delivered

Speaker: Dr Marco van Leeuwen (Utrecht University)

Slides 20160122_Bormio_ALICE_mvanleeuwen.pptx

09:45 Results from ATLAS and CMS: Strong Interactions and New Physics

No Abstract delivered

Speaker: Prof. Siegfried Bethke (Max Planck Institut fuer Physik)

Slides Bethke-Bormio2016.pdf

10:30 Coffee Break

11:00 Recent results on hyperons and the EOS.

No abstract delivered

Speaker: Dr Stefano Gandolfi (LANL)

Slides bormio2016_gandolfi.pdf

11:30 News from RHIC

No abstract delivered

Speaker: Dr Alexander Schmah (LBL)

Slides aschmah_Bormio_2016_V1.pdf

12:00 Recent results from the HADES experiment

no abstract delivered

Speaker: Dr Romain Holzmann (GSI)

Slides Bormio2016_v5_holzmann.pdf

17:00 → 19:30 Tuesday Afternoon

17:00 Experimental Tests of Charge Symmetry Breaking in Hypernuclei

Charge symmetry of the strong interaction predicts that the Λp and Λn interaction and consequently their contribution to the binding energies of mirror hypernuclei are identical. In the system of A=4 hypernuclei, however, emulsion measurements found an exceptionally large difference of 0.35 ± 0.05 MeV for the ground state binding energies. Very recently gamma-ray measurements in Λ-He4 at J-PARC indicate that the breaking of the symmetry is large in the 0+ ground state but is nearly vanishing in the 1+ excited state, demonstrating that the symmetry breaking part in the ΛN interaction has a strong spin dependence. The effect resists a consistent reproduction by theory until today and makes a confirmation of all binding energies in the A=4 system with independent experimental techniques desirable, especially since there is no exact knowledge about the systematic uncertainty for the emulsion data. The first observation of Λ-H4 by means of decay-pion spectroscopy with a high resolution magnetic spectrometer was performed 2012 at the Mainz Microtron MAMI. Demonstrating an almost one order of magnitude higher precision, it showed to be consistent with the emulsion result, while being limited by systematic uncertainties. In 2014, an extended measurement campaign was performed with improved control over systematic effects, increasing the yield of observed hypernuclei and confirming the measurement with two spectrometers at the same time. All values for the Λ-H4 binding energy measured at MAMI are consistent with a large charge symmetry breaking effect that leads to a 0.24 MeV binding energy difference in the A = 4 system when combined with emulsion data.

Speaker: Dr Patrick Achenbach (Mainz University)

Slides Achenbach-Bormio-2016.pptx

17:20 No Low-Lying Nuclear Vibrations: Configuration Dependent Pairing and Axial Asymmetry

Classical macroscopic considerations indicate that the nuclear surface energy is too strong to allow shape vibrations of the nucleus low enough in energy to be found within the pairing gap. The experimental evidence for the need for configuration dependent pairing to explain low-lying ex-“β vibration” 0+ states in deformed nuclei will be reiterated. The low-lying Kπ=2+ ex-“γ vibration” states observed in most deformed nuclei are evidence for the breaking of axial symmetry. The success of recent very sophisticated relativistic mean field and triaxial projected shell model calculations will be discussed.

Speaker: Prof. John F. sharpey-Schafer (University of the Western Cape, South Africa)

Slides Bormio2016_talk_JFSS.pptx

17:40 SMASH - A new hadron transport approach for heavy ion collissions

SMASH is a new hadronic transport model designed to describe the non-equilibrium evolution of heavy-ion collisions. After a brief introduction to the model, it will be shown that SMASH correctly reproduces the cross sections and maintains detailed balance. First comparisons to pion rapidity spectra measured by FOPI and HADES will be presented, followed by predictions for strangeness production in pion-nucleus collisions as recently measured by HADES.

Speaker: Vinzent Steinberg (FIAS)

Movie CuCu.mov

Slides talk.pdf

18:00 Recent results on soft QCD topics from ATLAS

Measurements of the properties of charged particle production are presented from proton-proton collisions at different centre-of-mass energies with focus on the latest results from obtained in 13 TeV collisions in summer 2015. The results are compared to various Monte Carlo event generator models, which describe the data to different extend. Furthermore particle distributions sensitive to the underlying event in proton-proton collisions have been measured and are compared to theoretical models. A preview of the underlying event in 13 TeV collisions is included, which is generally well described by models tuned to lower energies. The effects of space-time geometry in the hadronization phase has been studied in the context of Bose-Einstein correlations. Correlation parameters between charged particles are investigated in p-p collisions at 900 GeV and 7 TeV, up to very high charged-particle multiplicities. The ATLAS Collaboration has also performed a first measurement of the inelastic pp cross-section at 13 TeV using minimum bias scintillators. Precision measurements of the t-differential elastic pp cross section in a dedicated run at 7 TeV centre-of-mass energy with the ALFA Roman Pot detector were used to measure the total cross section as well as the inelastic cross section. A study of diffractive dijet production is presented, where dijet events are studied together with the requirement of a large region of pseudorapidity devoid of hadronic activity. The data are compared with Monte Carlo models and are found to be better described by models including diffraction. The rapidity gap survival probability has also been estimated. The measurement of the exclusive gamma+gamma -> ll production cross-section in proton-proton collisions at a centre-of-mass energy of 7 TeV has been carried out in the electron and muon channels. Results are found to be consistent
 with theory calculations only when taking into account proton absorptive 
effects due to finite proton size.

Speaker: Roman Lysak (Prague AS)

Slides 4-Lysak.pdf

18:20 Ab initio valence-space theory for exotic nuclei

Recent advances in ab initio nuclear structure theory have led to groundbreaking predictions in the exotic medium-mass region, from the location of the neutron dripline to the emergence of new magic numbers far from stability. Playing a key role in this progress has been the development of sophisticated many-body techniques and chiral effective field theory, which provides a systematic basis for consistent many-nucleon forces and electroweak currents. Within the context of valence-space Hamiltonians derived from the nonperturbative in-medium similarity renormalization group (IM-SRG) approach, I will discuss the importance of 3N forces in understanding and making new discoveries in the exotic sd-shell region. Beginning in oxygen, we find that the effects of 3N forces are decisive in explaining why 24O is the last bound oxygen isotope, validating first predictions of this phenomenon from several years ago. Furthermore, 3N forces play a key role in reproducing spectroscopy in neighboring isotopic chains and physics beyond the driplines. Finally, I will discuss first applications of the IM-SRG to effective valence-space operators, such as radii and E0 transitions, as well as extensions to general operators crucial for our future understanding of electroweak processes, such as neutrinoless double-beta decay.

Speaker: Dr Jason Holt (TRIUMF)

Slides Holt_2016_01_Bormio.pdf

18:40 Beyond the thermal model

The statistical hadronization (or thermal) model was initially developed by Hagedorn for hadron collisions above 10 GeV/c primary laboratory momentum [1]. In relativistic heavy-ion physics, many authors have developed it further and compared to a large amount of data in particular for hadron production rates, e.g. [2,3,4], where it yields excellent results. To decide whether the system is indeed in thermal equilibrium, the distribution functions rather than production yields are decisive: In the transverse momentum distributions of produced particles, deviations from thermal behaviour plus collective expansion occur beyond about 8 GeV/c. Not only the rapidity distributions of net baryons, but also the pseudorapidity distributions of produced mesons deviate from pure thermal behaviour: the thermal model does not generate a plateau in dN/dy, or a dip in dN/deta. Such non-equilibrium effects can to a certain extent be accounted for in a relativistic diffusion model [5,6] with three sources - two fragmentation sources, and a mid-rapidity source arising from gluon-gluon collisions - that merges with the thermal model for time to infinity. Given the short interaction times of AuAu at RHIC or PbPb at LHC, the fragmentation sources still contribute substantially, providing good results when compared [6,7] to data from PHOBOS and ALICE, and also for asymmetric systems such as dAu at RHIC and pPb at LHC. [1] R. Hagedorn, Nuovo Cim. Suppl. 3, 147 (1965) [2] P. Braun-Munzinger, J. Stachel, J. Wessels, N. Xu, Phys. Lett. B 344, 43 (1995) [3] A. Andronic, P. Braun-Munzinger, J. Stachel, Nucl. Phys. A 772, 167 (2006) [4] J. Manninen, F. Becattini, Phys. Rev. C 78, 054901 (2008) [5] G. Wolschin, Eur. Phys. J. A 5, 85 (1999) [6] G. Wolschin, J. Phys. G 40, 45104 (2013); Phys. Rev. C 91, 014905 (2015) [7] P. Schulz, G. Wolschin, Eur. Phys. J. A 51, 18 (2015)

Speaker: Prof. Georg Wolschin (U Heidelberg)

Slides Bormio2016_wolschin.pdf

Wednesday 27 January

09:00 → 13:25 Wednesday Morning

09:00 Facility for Rare Isotope Beams – Science and Status

not given

Speaker: Dr Georg Bollen (NSCL-MSU)

Slides _Bollen_FRIB_Bormio.pdf

09:45 Results from CMS and ATLAS: Electro-weak Symmetry Breaking and Beyond

no abstract delivered

Speaker: Dr Paolo Azzurri (INFN Pisa)

Slides AzzurriBormio.pdf

10:30 Coffee Break

11:00 Current topics in nuclear structure theory

no abstract delivered

Speaker: Dr Gaute Hagen (ORNL)

Slides Bormio_2016_GH.pdf

11:45 Heavy Ion Results from LHCb

No abstract delivered

Speaker: Dr Michael Schmelling (Max Planck Institute)

Slides Bormio_Michael_Schmelling.pdf

17:00 → 19:30 Wednesday Afternoon

17:00 Internal Target Experiments at the MESA accelerator

The Mainz Energy recovery Superconducting Accelerator (MESA) is currently under construction. The accelerator principle of an energy recovery linac will provide a high polarized electron beam with a beam current of up to 10mA with high polarization and an excellent beam quality at the same time, however at a modest end-point energy of around 100 MeV. The high internal current allows to use a low density gas target for high precision experiments. In this talk, the current design of the experimental setup for these experiments will be presented and possible experiments will be discussed.

Speaker: Dr Harald Merkel (Institut für Kernphysik, Johannes Gutenberg-Universität Mainz)

Slides MerkelBormio2016.pdf

17:25 Precision mass measurements of neutron-rich cadmium for r-process studies

The rapid neutron capture process (r-process) is believed to be responsible for the creation of a big portion of the elements heavier than iron. The path of the r-process proceeds in a region of the chart of nuclides where no or little experimental information is available. While astrophysical scenarios are available, they are all require significant experimental input from nuclear physics. Relevant experimental quantities constraining r-process calculations include binding energies, half-lives, neutron capture cross section, most of which are only provided through theoretical extrapolations. It is thus a long-standing experimental goal to identify and measure the properties of nuclides which are thought to contribute the most to the observed r-process abundances. An important region of interest is the A $\approx$ 130 abundance peak, associated to the classical waiting-point nucleus $^{130}$Cd. The Penning-trap mass spectrometer ISOLTRAP, situated at ISOLDE/CERN, is primarily dedicated to precision mass measurements of radioactive isotopes, from which their binding energies can be determined. In a recent experiment, ISOLTRAP measured the masses of the neutron-rich $^{129-131}$Cd isotopes. In this contribution the current ISOLTRAP setup will be presented as well as the techniques employed for mass measurements of cadmium isotopes. Furthermore we will discuss the impact of the measured masses on nuclear astrophysics.

Speaker: Dinko Atanasov (Max-Planck Institute for Nuclear Physics)

Slides DA_129-131Cd-Bormio.pptx

17:45 Beyond the isobar model

From new precise data of the modern experiments, it becomes clear that the pure isobar model works only qualitatively and not able to describe the data in presence of many inelastic channels. The final state interactions modify the shape of isobars and produce additional structures on the Dalitz plot as well as on the 3 particles mass distribution. The first order correction to the isobar model is the triangle diagram. We discuss the effects of the rescattering on the several examples: $3\pi$ final state, $J/\Psi\,p\,K$ final state and $J/\Psi\,\pi\,\pi$ final state. Modern technique for data analysis with the unitarity constraint is presented.

Speaker: Mr Mikhail Mikhasenko (HISKP, Uni Bonn)

Slides Mikhasenko-Beyond_the_IM.v1.pdf

18:05 Measurement of the ridge and bose-enstein correlations in pp and pPb collisions with the ATLAS detector at the LHC

ATLAS measurement of azimuthal correlations between particle pairs at large pseudorapidity separation in pp and pPb collisions are presented. The data were collected using a combination of the minimum-bias and high track-multiplicity triggers. A detailed study of the dependence of two-particle correlations on the charged particle multiplicity, transverse momentum of the pair constituents and the pseudorapidity separation between particles forming a pair is shown. Measurements of multi-particle cumulants in the azimuthal angles of produced particles in wide pseudorapidity (|η|<2.5) and multiplicity ranges, with the aim to extract a single particle anisotropy coefficient, v1-v5, are also presented. These measurements can help to understand the origin of the long-range correlations seen in high-multiplicity pp and p+Pb collisions. In addition, one and three-dimensional HBT radii in p+Pb collisions are presented as a function of event centrality. An estimation of dE/dx in the pixel detector is used to identify charged pions. These particles are selected from |η| < 2.5 and the measurement is performed in several pair-average momentum (kT) bins from 0.1 GeV to 1.0 GeV. The measured source sizes are observed to increase with collision centrality. The contribution to the correlation function from hard processes is studied and a novel method for tuning the amplitude of this background in the data is introduced.

Speaker: Dr Michael Ryan Clark (CERN)

Slides clark_hbt_slides.pdf

18:25 Measurement of the beam normal single-spin asymmetry of Carbon-12

Beam-normal single-spin asymmetry in the elastic scattering of electrons is a direct probe for the two photon exchange. At the Mainz Mictrotron, this asymmetry has been measured for Carbon-12 at a Q² of 0.04 GeV². A 570 MeV continuous wave electrons beam was scattered on a carbon target and detected by two magnetic spectrometers. Quartz glass cherenkov detectors located at the elastic line in the spectrometer's focal plane were used to measure the amount of scattered electrons. The PMTs of which were read out with integrating current ADCs allowing for particle rates too high for counting. The resulting asymmetry shows a surprising deviation from theoretical predictions.

Speaker: Dr Anselm Esser (Inst. f. Kernphysik / Uni Mainz)

Slides AEsser.pdf

18:45 Charm Physics at BESIII

The BESIII Experiment at the Beijing Electron Positron Collider (BEPCII) has accumulated the world's largest e+e- collision samples at psi(3770) peak, around the psi(4040) nominal mass, and at the Lambda_c-pair mass threshold which allow us to study decays of charmed mesons and baryons in a uniquely clean background. In this talk, we will review our recent results including: (1) the extractions of the D(s)+ decay constants, the form factors of D semi-leptonic decays, and the CKM matrix elements |Vcs(d)|; (2) the measurements of the strong phase and D0D0-bar mixing parameters using quantum coherence; (3) the determinations of the absolute branching fractions of the hadronic and semi-leptonic decays of Lambdac+.

Speaker: Dr Li Lei (ihep)

Slides charm_physics_at_BESIII_LiLei.pdf

Thursday 28 January

09:00 → 13:25 Thursday Morning

09:00 Signatures of the early Yang Mills phase in a novel high multiplicity event class in pBar-p ‎and pA colliders FAIR*, NICA, RHIC and LHC

The nearly quarkless early stage of high multiplicity collider events allows to study dense , hot and cold cosmic matter, its changing phase structure and its transport and nonequilibrium properties in the laboratory. Experimental ‎observables which allow for detection of such novel forms of matter are discussed.

Speaker: Prof. Horst Stoecker (GSI and J.W. Goethe Universitaet)

Slides BASIC_New_Horizons_-_from_Lattice_QCD_via_Hadron_Yields_to_Pure_Yang_Mills_Matter_HSt_2015.pptx

09:45 Charm Physics: Where Color meets Flavor

The charm quark as an intermediate case between the light and the heavy quarks is on then hand an interesting laboratory to test QCD, e.g. by the spectroscopy of its hadronic states, on the other hand it provides an important source for the flavor physics of an up-type quark. In this talk I plan to give a short overview of these two interlinked aspects of charm physics.

Speaker: Prof. Thomas Mannel (University of Siegen)

Slides Mannel-Charm.pdf

10:30 Coffee Break

11:00 Novel developments in imaging and dosimetry for Hadrontherapy.

No abstract delivered

Speaker: Prof. Vincenzo Patera (INFN-LNF)

Slides Patera_Bormio_280116.pdf

11:30 Flavour results from LHCb

No abstract delivered

Speaker: Prof. Marcel Merck (Nikhef)

Slides LHCbMerk.pdf

17:00 → 19:40 Thursday Afternoon

17:00 From Coulomb breakup of halo nuclei to neutron radiative capture

Coulomb breakup has been proposed as an indirect method to deduce the cross section of radiative captures of astrophysical interest [1]. In Coulomb breakup, the projectile dissociates into lighter fragments through its interaction with a heavy (high Z) target. Assuming the dissociation to be due to the sole Coulomb interaction, the reaction can be described as an exchange of virtual photons between the projectile and the target. It can thus be seen as the time-reversed reaction of the radiative capture of the fragments, which should enable us to deduce easily the radiative-capture cross section from breakup measurements [1]. Using accurate reaction models, various studies have shown that higher-order effects and other reaction artefacts play a significant role in Coulomb breakup, which hinder the simple extraction of radiative-capture cross sections from breakup measurements [2,3]. Nevertheless, recent analyses show that accurate calculations of the breakup of 15C on Pb at 70AMeV can be used to deduce the Asymptotic Normalisation Coefficient (ANC) of the 15C bound state from experimental data [4,5]. These analyses suggest that this ANC can then be used to compute a cross section for the 14C(n,g) radiative capture in agreement with direct measurements. In the present work the influence of the description of the 15C continuum upon breakup calculations is analysed. Interestingly, it is shown to be nearly as significant as that of the ANC. Fortunately, it can be accounted for by fitting the theoretical predictions to the breakup data in the low 14C-n energy range. These results revive the original idea of inferring radiative-capture cross sections from Coulomb breakup measurements. In addition to its application in nuclear astrophysics, this work also indicates which information of the structure of the projectile actually matters in reaction modelling. This shows how the simple description of nuclei used in accurate reaction codes could be improved from state-of-the-art nuclear-structure models. [1] G. Baur, C. A. Bertulani, and H. Rebel, Nucl. Phys. A458, 188 (1986). [2] H. Esbensen, G. F. Bertsch, and K. A. Snover, Phys. Rev. Lett. 94, 042502 (2005). [3] P. Capel and D. Baye, Phys. Rev. C 71, 044609 (2005). [4] N. C. Summers and F. M. Nunes, Phys. Rev. C 70, 011602 (2004). [4] H. Esbensen, Phys. Rev. C 80, 024608 (2009).

Speaker: Prof. Pierre Capel (Univ. Bruxelles)

Slides capelBormio16.pdf

17:25 Proton-proton and Lambda-proton correlations measured in p+Nb collisions at 3.5 GeV with HADES

In the last years, the hyperon-nucleon interaction became the focus of attention by an astrophysical measurement of a quite heavy neutron star of two solar masses. Model calculations, which try to describe such a heavy star usually fail, because of the appearance of hyperons in the model predictions which lead to a too strong softening of the equation of state. Because the models need input from the experimental side this motivates to study the interaction of hyperons with ordinary matter because the experimental data on this topic is quite scarce. With the High Acceptance Di-Electron Spectrometer (HADES) located at GSI in Darmstadt (Germany) the reaction p+Nb with a kinetic beam energy of 3.5 GeV was measured. We explore the two-particle correlation function of protons to explore the system size, where these di-hadron pairs were emitted from. This information is useful to pin down the source size of another pair namely of Lambda-Proton. This opens the possibility to focus only on the investigation of the final state interaction of the Lambda-Proton pair. We will present this strategy and results of a comparison of different model predictions with the experimental data.

Speaker: Mr Oliver Arnold (Technische Universitaet Muenchen)

Slides oarnold_bormio2016.pdf

17:45 From hypernuclei to neutron stars: looking for the pieces of the puzzle

The onset of hyperons in the core of neutron stars and the consequent softening of the equation of state have been questioned for a long time. We tackle the problem within a quantum Monte Carlo computational scheme. We first show that a repulsive three-body hyperon-nucleon force is needed to correctly describe the systematics of Λ-hypernuclei [1,2,3]. Then, we employ the same potential to determine the equation of state and the mass-radius relation of an infinite system of neutrons and Λ particles [4]. We find dramatic effects on the predicted maximum mass depending on the details of the three-body hyperon-nucleon force. Our results suggest that stronger constraints on the hyperon-neutron force are necessary in order to properly assess the role of hyperons in neutron stars. This work is supported by the U.S. Department of Energy, Office of Nuclear Physics, under the NUCLEI SciDAC grant. Computer time was made available by the National Energy Research Scientific Computing Center (NERSC), which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. [1] D. Lonardoni, S. Gandolfi, F. Pederiva, Phys. Rev. C 87, 041303(R) (2013) [2] D. Lonardoni, F. Pederiva, S. Gandolfi, Phys. Rev. C 89, 014314 (2014) [3] F. Pederiva, F. Catalano, D. Lonardoni, A. Lovato, S. Gandolfi, arXiv:1506.04042 (2015) [4] D. Lonardoni, A. Lovato, S. Gandolfi, F. Pederiva, Phys. Rev. Lett. 114, 092301 (2015)

Speaker: Dr Diego Lonardoni (MSU)

Slides Lonardoni.pdf

18:05 DEPFET for BELLEII

The Belle II experiment is a B-factory which is being built at the asymmetric electron-positron collider SuperKEKB in Japan. The experiment aims at measuring the differences between matter and anti-matter in the B and D meson decays. The 2-layer active pixel detector based on the novel DEPFET technology is an innermost detector in the experiment and a part of the vertex detector. The pixel detector provides excellent spacial resolution of around 10 um and low material budget of 0.19% X0/layer. Furthermore, the energy loss in the detector will be used for the characterization of the incident particles. The working principle of the detector as well as the current development status will be presented in the talk.

Speaker: Dima Levit (tum)

Slides Levit_belle2_pxd.pdf

18:25 Measurements of heavy flavours with the ALICE experiment at the LHC

Fluctuations of various observables in heavy-ion collisions at ultra-relativistic energies have been extensively studied as they provide important signals regarding the formation of Quark Gluon Plasma. Because of the large number of produced particles in each event, a detailed study of event-by-event multiplicity fluctuations has been proposed as one of the signatures of the phase transition. In addition, the understanding of multiplicity fluctuations is essential for other event-by-event measurements. In the present work, we have measured the scaled variance ($\omega=\sigma^2 / \mu$) of the charged particle multiplicity distributions as a function of centrality in Pb-Pb collisions at LHC energies. Here, $\mu$ and $\sigma$ denote the mean and the width of the multiplicity distributions, respectively. We will show how these quantities evolve with centrality, and discuss the influence of volume fluctuations on these measurements. Our results provide vital input to theoretical model calculations.

Speaker: Mrs Denise Godoy (ss)

Slides DeniseGodoy.pdf

18:45 Exotic quarkonium states in CMS

Using large data samples of di-muon events, CMS has performed detailed measurements and searches for new states in the field of exotic quarkonium. We present our results on the production of prompt and non-prompt X(3872), detected in the J/ψ ππ decay channel, which extend to higher pT values than in any previous measurement. The cross-section ratio with respect to the ψ(2S) is given differentially in pT (as well as pT integrated). For the first time at the LHC, the fraction of X(3872) coming from B hadron decays has been measured. The analysis includes a measurement of the di-pion mass spectrum, establishing that the decay takes the form J/ψ ρ. After these studies of the charmonium X, we present a new search for its bottomonium counterpart, denoted as Xb, based on a data sample of pp collisions at 8 TeV collected by CMS in 2012. In analogy to the X(3872) studies, the analysis uses the Xb to Υ(1S) ππ exclusive decay channel, with the Υ(1S) decaying to μμ pairs. We will also report from the two structures found in the J/ψ φ decay channel, accessed through the exclusive B+ → J/ψ φ K+ decay. One of the structures confirms a previous observation by the CDF experiment, while the second structure has been observed by CMS for the first time. These contribute to the "systematic" studies of new structures in the search for new exotic quarkonium states, which provides an effective method to test QCD predictions. There have been several proposals explaining these states as hybrid (𝑞𝑞𝑔) or four-quark (𝑞𝑞 𝑞𝑞) exotic mesons. These two results clearly demonstrate CMS' capability to perform detailed studies on exotic quarkonium production. CMS is currently extending these studies to other exotic quarkonium states and new results are very likely to be ready in view of the present conference

Speaker: Mr Leonardo Cristella (CERN)

Slides Cristella_Bormio.pdf

Friday 29 January

09:00 → 12:45 Friday Morning

09:00 The Belle2 Experiment

No abstract delivered

Speaker: Prof. Peter Krizan (Ljubljana University and J. Stefan Institute)

Slides bormio2016-krizan.pdf

09:45 Lattice QCD in 2016: recent results and what to expect

no abstract delivered

Speaker: Prof. Ryan Sinead (Trinity College, Dublin)

Slides SRyan.pdf

10:30 Coffee Break

11:00 Recent and future studies of exotic nuclei.

no abstract delivered

Speaker: Dr Alexandre Obertelli (CEA)

Slides ExoticNuclei_Bormio2016_web.pdf

11:45 Hadron Spectroscopy at LHCb

The LHCb experiment is designed to study the decays and properties of heavy flavoured hadrons produced in the forward region from pp collisions at the CERN Large Hadron Collider. During Run1, it has recorded the world’s largest data sample of beauty and charm hadrons, enabling precise studies into the spectroscopy of such particles, including discoveries of new states in the meson as well as the baryon sector and measurements of their properties such as masses, widths and quantum numbers. The latest results in this area are reviewed.

Speaker: Dr Sebastian Neubert (Heidelberg University)

Slides bormio16_sneubert.pdf

12:15 Correlations in nuclei.

no abstract delivered

Speaker: Dr Or Hen (MIT)

Slides Hen_Bormio_Jan2016.pdf

17:00 → 19:30 Friday Afternoon

17:00 Symmetry unrestricted Skyrme mean-field study of heavy nuclei

In the light of recent experimental developments, increasing attention is devoted to nuclear phenomena related to rotational excitations of more exotic intrinsic nuclear configurations that often lack certain symmetries often present in the majority of nuclei. Examples include configurations with a non-vanishing octupole moment. In order to describe this kind of states, we have developed a new method for self-consistent mean-field calculations, using effective Skyrme interactions in a coordinate-space representation. The code is based on the same principles as the EV8 code [1], but all symmetry assumptions assumed in EV8 (e.g. parity) can be individually relaxed. Another important generalisation is the replacement of the HF+BCS by the full machinery of Hartree-Fock-Bogoliubov transformations. Another important aspect is that the code is fully equipped to deal with a large number of effective Skyrme interactions, which have been fitted in a multitude of different ways over the years [1]. To the best of our knowledge, there is at present only one other code that offers the same flexibility for self-consistent mean-field calculations [5], and which differs from ours by expanding the single-particle wave functions on an oscillator basis. The first applications of this method are presently under investigation. The first one concerns the tilted axis cranking in the rare earth region which necessitates the breaking of both time-reversal and at least one spatial symmetry. A second application concerns the octupole deformed nuclei in the A=220 region. We will address low-lying non-collective states in even and odd Ra isotopes, for which data are available and also odd-A Fr isotopes for which detailed experiments are planned in the near future. References [1] P. Bonche, H. Flocard, P.-H. Heenen, Comp. Phys. Comm. 171 (2005) 49; W. Ryssens, V. Hellemans, M. Bender, P.-H. Heenen, Comp. Phys. Comm. 187 (2015) 175. [2] P. Bonche, P.-H. Heenen, H. Flocard, D. Vautherin, Phys. Lett. B 175 (1986), 387. [3] P. Bonche, H. Flocard, P.-H. Heenen, Nucl. Phys. A 467 (1987) 115. [4] B. Gall, P. Bonche, J. Dobaczewski, H. Flocard, P.-H. Heenen, Z. Phys. A 348 (1994) 183. [5] J. Dobaczewski et al, Comp. Phys. Comm. 180 (2009) 2361.

Speaker: Mr Wouter Ryssens (ULB)

Slides Bormio2016.pdf

17:20 Measurement of neutral mesons in pp and Pb-Pb collisions at midrapidity with the ALICE experiment at the LHC

Neutral mesons, such as $\pi^{0}$ and $\eta$, are probes for the study of the energy loss of partons traversing the hot and dense medium, the Quark-Gluon Plasma, that is formed in heavy-ions collisions. Moreover, they represent the largest background for the direct photon measurement and an accurate estimate is therefore necessary to determine the decay photon contribution. The ALICE experiment measures $\pi^{0}$ and $\eta$ mesons via the two-gamma decay channel. The photon detection can either be direct, using the electromagnetic calorimeters EMCal and PHOS, or by reconstructing the electron-positron pairs from photon conversions in the detector material (photon conversion method, PCM). With the PCM, photons are reconstructed using the ALICE Inner Tracking System (ITS) and the Time Projection Chamber (TPC). This method has full azimuthal coverage, which compensates for the small conversion probability. It provides a precise measurement at low transverse momentum. The calorimeters have reduced acceptance but trigger capabilities and provide the high $p_{\mbox{\tiny{T}}}$ measurement, where they also have good energy resolution. The errors from these measurements are independent thus their comparison is a good cross check and their combination gives a more precise result. In this presentation, we will show the $\pi^{0}$ and $\eta$ spectra in Pb--Pb collisions at $\sqrt{s_{\mbox{\tiny NN}}}$ = 2.76~TeV and pp collisions at different center of mass energy obtained over a wide transverse momentum range.

Speaker: Ms Lucia Leardini (Physikalisches Institut (PI) Heidelberg)

Slides BormioWM2016_Leardini.pdf

17:40 Quasi-free one-nucleon Knockout Reactions on neutron-rich Oxygen Isotopes

According to the Independent Particle Model (IPM) the single particle states are fully occupied with a spectroscopic factor one. However in electron-induced proton knockout reactions a reduction of single-particle strengths has been observed to about 60-70% for stable nuclei in comparison to the IPM. This finding has confirmed by nuclear knockout reactions using stable and exotic beams however with a strong dependency on the proton-neutron asymmetry. To understand this dependency quantitatively a complementary approach, quasi-free reactions, is introduced. Quasi-free knockout reactions in inverse kinematics at relativistic energies allow us to investigate single-particle structure of stable and exotic nuclei in a most direct way. We have performed a systematic study of spectroscopic strength of Oxygen isotopes using quasi-free (p,2p) and (p,pn) knockout reactions. The Oxygen isotopes offer a large variation of separation energies which allow us to obtain a quantitative understanding of spectroscopic factors in a large variation of isospin asymmetry. For this we performed an experiment at the R3B/LAND setup (at GSI in Darmstadt, Germany) with secondary beams containing 14−24O. The 16−18O and 21−23O isotopes have been analyzed so far and the preliminary results will be presented. The results include cross sections, momentum distributions and gamma-coincidence measurements. By comparison with the eikonal reaction theory the spectroscopic and reduction factors have been extracted and will be compared to existing data. The work is supported by HIC for FAIR, GSI-TU Darmstadt cooperation, and BMBF project 05P12RDFN8.

Speaker: Leyla Atar (TU Darmstadt)

Slides LAtar_Bormio_2016.pdf

18:00 Measurements of 12C ion fragmentation on thin Au target from the FIRST collaboration at GSI

The study of the nuclear fragmentation processes occuring in the interaction of highly energetic ions in matter is of great interest both in basic research (e.g. to improve the understanding of hadronic showers development in the atmosphere) and in applied physics, in particular in cancer therapy and space radiation protection fields. Accurate measurements of fragmentation cross sections of light ions interacting with elemental and composite targets are crucials to benchmark and improve the nuclear interaction models implemented in Monte Carlo (MC) simulation codes. In order to provide the necessary experimental input to MC simulations, a small set of measurements can be used: the interpolation of cross sections for different energies and target materials composition allows, starting from a selected number of target/energy combinations, to build a model covering all the application needs. The current agreement between predictions of nuclear interaction models implemented in MC codes and experimental data is encouraging but there is still room for improvement, mainly due to the lack of available data and to their limited precision. So far, only yields or total and partial charge-changing fragmentation cross sections have been measured with high precision and in a variety of target and beam energy configurations. However the most valuable results, the double differential cross section measurements, that would allow a stringent test of the nuclear model predictions, are still missing. In particular, while the fluences and the total cross sections are currently well described, the production of light fragments and their angular distribution is affected by large uncertainties and different algorithms are predicting yields that can differ up to an order of magnitude. The NASA recently completed a survey of a large data base [1] of measured nuclear fragmentation cross sections including approximately 50000 datasets, and concluded that several experimental data are missing, including double differential cross sections for carbon ions at energies below 400 MeV/nucleon. The FIRST (Fragmentation of Ions Relevant for Space and Therapy) experiment at the Helmholtz Center for Heavy Ion research (GSI) was designed and built by an international collaboration from France, Germany and Italy in order to perform precise measurements of the fragmentation cross sections of a 12C ion beam with different thin targets. The experiment main purpose was to measure the fragmentation double differential cross sections at different angles and energies between 100 and 1000 MeV/nucleon, of interest for applications in particle therapy and radio-protection in space. In this contribution we present the analysis of data collected with the FIRST apparatus using a 12C beam of 400 MeV/nucleon impinging on a 0.5 mm Au target. The experimental setup was optimized to study two distinct angular regions: the small angle region (subject of this contribution), where fragments are produced with a polar angle (theta) with respect to the impinging beam direction (z axis) smaller than 5◦ and a large angle region with theta between 5◦ and 40◦. The analysis techniques used for the fragments reconstruction in the forward angular region and the results of the elemental and isotopic single differental cross sections with respect to fragment angle and energy will be discussed. The obtained results will be compared with the available experimental results. The comparison with a detailed FLUKA MC simulation will be reported as well. [1] J. W. Norbury, J. Miller et al., Review f Nuclear Physics Experiments for Space Radiation, NASA/TP2011- 217179, (2011).

Speaker: Dr Marco Toppi (infn)

Slides MarcoToppi_Bormio.pdf

18:20 Symmetry energy and density

The nuclear equation-of-state is a topic of highest current interest in nuclear structure and reactions as well as in astrophysics. In particular, the equation-of-state of asymmetric matter and the symmetry energy representing the difference between the energy densities of neutron matter and of symmetric nuclear matter are not sufficiently well constrained at present. The density dependence of the symmetry energy is conventionally expressed in the form of the slope parameter L describing the derivative with respect to density of the symmetry energy at saturation. Results deduced from nuclear structure and heavy-ion reaction data scatter around a mean value L=60 MeV. Recent studies have more thoroughly investigated the density range that a particular observable is predominantly sensitive to. Two thirds of the saturation density is a value typical for the information contained in nuclear-structure data. Higher values exceeding saturation have been shown to be probed with meson production and collective flows at incident energies in the range of up to about 1 GeV per nucleon. From the measurement of the elliptic-flow ratio of neutrons with respect to light charged particles in recent experiments at the GSI laboratory, a new more stringent constraint for the symmetry energy at supra-Saturation density has been deduced. It confirms, with a considerably smaller uncertainty, the moderately soft to linear density dependence of the symmetry energy previously deduced from the FOPI-LAND data. Future opportunities offered by FAIR will be discussed.

Speaker: Prof. Wolfgang Trautmann (GSI Helmholtzzentrum Darmstadt)

Slides Bormio_2016_Trautmann.pptx