Abstract book: Parallel­4

Parallel-4

A-4224A89A165A121A

C1-4266C74C190C153C

C2-4119C268C30C187C

G-2258G71G90G166G

E-4256H46E54E110E

JK-2138K97J188K

Nuclear Fission Dynamics Aurel Bulgac

Department of Physics, University of Washington, Seattle, WA 98195-1560, USA

Nuclear fission presents one of the oldest, if not the oldest challenge to theoretical many-body physics in literature, turning 80 years old next year and still awaiting a fully quantum microscopic description with a robust predictive power. Since its experimental discovery in 1939 only a few theoretical results have been firmly established in the quantum theory of fission: i) the competition between the surface tension and the Coulomb energy within the liquid drop model by Meitner and Frisch (1939); ii) the formation of the compound nucleus and its shape evolution towards the outer saddle barrier by Bohr and Wheeler (1939); iii) the role of shell effects by Meitner (1050) and the formation of the second fission barrier by Strutinski (1967); and the use of the statistical model to describe the decay of the fission products, Weisskopf (1935) and Hauser and Feshbach (1952). A number of theoretical and phenomenological models based on untested assumptions have been proposed and used: i) the generator coordinate method and the closely related adiabatic time-dependent Hartree-Fock method; ii) the classical Langevin and Fokker-Planck equations; scission point model and others somewhat similar phenomenological models.

Two major recent developments in theory and computational resources created however the favorable conditions for achieving a microscopic description of fission dynamics. The first major development was in theory, the extension of the Time-Dependent Density Functional Theory to superfluid fermion systems. The second development was in computing, the emergence of powerful enough supercomputers capable of solving the complex systems of equations describing the time evolution in three dimensions without any restrictions of hundreds of strongly interacting nucleons.

The evolution of the compound nucleus from the moment the neutron is absorbed until the saddle is reached was left basically in the dark, and most of the attention was concentrated on the evolution of the nucleus from the saddle-to-scission and fission fragment formation. The main assumption was that this process is slow and moreover adiabatic, an assumption which allowed the separation of the degrees of freedom into collective and intrinsic. Being slow does not imply adiabaticity however. The fission dynamics from saddle-to-scission is slow, or quasi-static, but the intrinsic system gains a lot of entropy, and the energy gained from the collective degrees of freedom is never relinquished. The fission dynamics from the saddle-to-scission is much slower than the adiabatic assumption would imply, the collective flow energy never exceeding 1-2 MeV and the rest of the difference between the potential energy at the saddle and at the scission point is almost entirely converted into intrinsic energy or heat, Bulgac et al., arXiv:1806.00694. This finding will require a complete retooling of most theoretical approaches used so far. The recent development of a fully quantum approach to dissipation and fluctuations in the formation of the fission fragments, Bulgac et al. arXiv:1805.08908, lent even more support to this finding. Dissipation and fluctuations, due to the strong coupling between the collective and intrinsic degrees of freedom, break all symmetries and the fission times are typically longer. Agreement with experiment is surprisingly good, in spite of the fact that no parameters have been fitted and the results are rather stable with parameter changes.

0224

Quantum surface friction modelfor fusion reactions around the Coulomb barrier

M. Tokieda1 and K. Hagino1

1Department of Physics, Tohoku University, Sendai 980-8578, Japan

For the description of heavy-ion fusion reactions at energies above the Coulomb barrier, theclassical trajectory calculation with a frictional force has been developed. The necessity of africtional force was suggested by the experimental fact that a large amount of energy loss takesplace in scattering experiments, which now is known as deep inelastic scattering. Although theclassical friction model can nicely describe above barrier fusion reactions, apparently it cannotbe applied to fusion reactions at energies below the Coulomb barrier, where fusion reactionstake place only by quantum tunneling. A difficulty arises when one tries to incorporate africtional force into the formalism of quantum mechanics. One cannot simply add a frictionalforce to the equation of motion, as is done in the classical model, because quantum mechanicsis not based on the equation of motion, but on Hamiltonian.

In order to achieve a unified description of sub- and above barrier fusion reactions, wefocus on a phenomenological quantum friction model invented by M.D. Kostin [1], in whichHamiltonian is modified so that the equation of motion with a frictional force is reproduced inthe classical limit. With that model, we carry out quantum mechanical calculation of fusionreactions with a frictional force. For the form of a frictional force, we employ the surfacefriction model, which is known to be one of successful models of classical trajectory calculation[2]. In the presentation, we shall show that fusion cross sections with the quantum friction arein between fusion cross sections without friction and that of the classical trajectory calculation,and they provide better agreement with experimental data, as shown in Fig.1.

FIG. 1: Comparison of experimental fusion cross sections for the 16O + 208Pb system (the red circles)with the quantum surface friction model (the black solid lines), the quantum no friction calculation (theblue dashed lines), and the classical surface friction model (the green dotted lines). The left panel is inthe linear scale and the right panel is in the logarithmic scale.

[1] M.D. Kostin, J. Chem. Phys. 57, 3589 (1972).[2] P. Frobich, Phys. Rep. 116, 337 (1984)

0089

Neutron multiplicity measurements for the near super-heavy nucleus 260Rf

Meenu Thakur1a, B.R. Behera1, Ruchi Mahajan1, N. Saneesh2, GurpreetKaur1, M. Kumar2, A. Yadav2, N. Kumar3, Kavita Rani1, H. Arora1, D. Kaur1, S. Narang1,

Kavita4, R. Kumar4, P. Sugathan2, A. Jhingan2, K. S. Golda2, A.Chatterjee2, S. Mandal3, A. Saxena5, and S. Kailas5, Santanu Pal6

1Department of Physics, Panjab University, Chandigarh - 160014, INDIA2Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi - 110067, INDIA

3Department of Physics and Astrophysics, University of Delhi - 110007, INDIA4Department of Physics, Kurukshetra University, Kurukshetra - 136119, INDIA

5Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai - 400085, INDIA6CS - 6/1, Golf Green, Kolkata 700095, India (Formerly with VECC, Kolkata)

* email: meenu.thakuroct@gmail.comaPresent address: Physics Department, Florida State University, Tallahassee, Florida

32306, USA

During last few decades, numerous attempts have been made to study the formation ofsuper-heavy elements [1] during last few decades. Such studies for super-heavy elementsget complicated as it receives the mixed contribution from quasi-fission (QF) and fusion-fission processes (FF) [2]. Experimental probes like fission fragment angular distribution,mass distribution (MD), mass-energy distribution (MED) and mass-gated neutron multi-plicity could be employed to disentangle these processes. Neutron emission probe is usedfor the systems where MD and MED fail to distinguish QF and FF [3] processes in the re-action dynamics of heavy elements. This probe makes use of the different time-scales ofthese processes to separate out their contributions. In this paper, we will report the studiesperformed by utilizing the neutron multiplicity measurements for the 28Si + 232Th systempopulating the near super-heavy compound nucleus (CN) 260Rf (Z=104) at an excitationenergy of 57.4 MeV, to study the fission dynamics of the 260Rf nucleus. The data havebeen collected during an experiment performed using the National Array of Neutron De-tectors (NAND) facility [4] with a pulsed beam of 28Si from the 15UD Pelletron +LINAC accelerator at Inter University Accelerator Centre (IUAC), New Delhi. In our re-cent published work, we have observed a significant contribution from the QF processesin the 48Ti + 208Pb system populating the compound nucleus 256Rf [5]. These results will becompared with the results for the 28Si + 232Th system to study the role of entrance chan-nels and shell effects on QF processes. The experimental results are also compared withthe predictions from the statistical model calculations.

References:

[1] J.H. Hamilton, S. Hofmann and Y.T. Oganessian, Annu. Rev. Nucl. Part. Sci. 63, 383(2013).[2] M.G. Itkis et al., Nucl. Phys. A 734, 136 (2004).[3] P.K. Sahu et al., Phys. Rev. C 72, 034604 (2005).[4] P. Sugathan et al., Pramana 83, 807 (2014).[5] Meenu Thakur et al., accepted in Phys. Rev. C.

0165

Origins of above-barrier fusion hindrance of light, weakly-bound nuclides

E. C. Simpson1, K. J. Cook1, Sunil Kalkal2, M. Dasgupta1, D. J. Hinde1, K. Banerjee1,

L. Bezzina1, and C. Sengupta1

1Department of Nuclear Physics, Research School of Physics and Engineering, The Australian National

University, Canberra, ACT 2601 Australia 2School of Physics and Material Sciences, Thapar University, Patiala-147004, India

Near-barrier collisions involving light, weakly-bound nuclei exhibit a diverse range of

reaction phenomenon, including direct breakup, nucleon transfer, and complete fusion. The

interplay of these different mechanisms is of great interest, since fusion reactions of 6,7,8Li, 9Be and 10,11B have been found to be significantly suppressed, by up to 35% [see 1 and refs.

therein]. Though a strong correlation between the lowest energy cluster breakup threshold

and the degree of fusion suppression has been found, the root cause of this suppression is not

well understood.

One possible cause of fusion suppression is projectile breakup. Direct reaction processes can

cause disintegration of the projectile into clusters, and if only part of the projectile is then

captured (often termed incomplete fusion), complete fusion will be reduced. Both direct

excitation and transfer reactions have been found to trigger breakup in 6,7Li and 9Be [2,3].

However, since the formation of a compound nucleus takes just 10-21 seconds, if breakup is to

suppress fusion, it must occur promptly: narrow resonance states, such as the 8Be 0+ ground

state, will not decay fast enough [3].

Stochastic classical dynamical models (SCDMs) allow simultaneous treatment of both direct

and transfer-triggered breakup, whilst also allowing predictions for complete and incomplete

fusion [4,5]. SCDMs treat the trajectories of the projectile and target classically, with

breakup treated stochastically given some assumed reaction probability function PBU(R) [6,7].

The properties of intermediate resonances are incorporated by allowing the reaction product

to propagate for some duration, determined from the known widths of the state, prior to

breakup. The resulting breakup fragments are then produced and propagated in the field of

the target-like nucleus until they fuse or escape. By constraining PBU(R) using sub-barrier

breakup or above-barrier no-capture breakup, cross sections for complete and incomplete

fusion may be predicted.

Recent work using SCDMs has highlighted the crucial role broad resonant states, such as the 8Be 2+, play in determining sub-barrier breakup outcomes [5], but also suggested that they

will not contribute to fusion suppression [6]. Here we discuss this key topic in near-barrier

reactions using the example of 7Li, where both direct and transfer-induced are strong, and

consider whether breakup followed by partial capture can explain the observed fusion

suppression.

[1] Wang et al., Phys. Rev. C 90, 034612 (2014).

[2] Shrivastava et al., Phys. Letts. B, 633, 463 (2006).

[3] Luong et al., Phys. Letts. B 695, 105 (2013)

[4] Diaz Torres et al., Phys. Rev. Letts. 98, 152701 (2007)

[5] Simpson et al., Phys. Rev. C 93, 024695 (2016)

[6] Cook et al., Phys. Rev. C 93, 064604 (2016)

[7] Kalkal et al., Phys. Rev. C 93, 044605 (2016)

0121

New Perspectives for Hadron and Nuclear Physics from Light Front Holography and Su-perconformal Algebra

Stanley J. BrodskySLAC National Accelerator Center, Stanford UniversityStanford, Californiasjbth@slac.stanford.eduAbstractA fundamental question in hadron and nuclear physics is how the mass scale for protons and other

hadrons emerges from QCD, even in the limit of zero quark mass. I will discuss a new approach to the originof the QCD mass scale and color confinement based on “light-front holography”, a formalism which relatesthe bound-state amplitudes in the fifth dimension of AdS space to the boost-invariant light-front wavefunc-tions describing the structure of hadrons in physical space-time. The result is a set of Poincar-invariantbound-state wave equations which incorporate quark confinement and predict many observed spectroscopicand dynamical features of hadron physics, such as linear Regge trajectories with identical slope in boththe radial quantum number and the internal orbital angular momentum. Generalizing this procedure usingsuperconformal algebra leads to a unified Regge spectroscopy of meson, baryon, and tetraquarks, includingremarkable supersymmetric relations between the masses of mesons and baryons. The pion bound-state,although composite, is massless for zero quark mass.One also can predict nonperturbative hadronic observ-ables such as structure functions, transverse momentum distributions, heavy quark distributions and thedistribution amplitudes defined from the hadronic light-front wavefunctions. The analytic behavior of theQCD coupling controlling quark and gluon interactions at large and small distances is also determined. Theresult is an effective coupling defined at all momenta with a transition mass scale which sets the interfacebetween perturbative and nonperturbative hadron dynamics. One also obtains a relation between the per-turbative QCD mass scale and hadron masses. I will also discuss the novel implications for nuclear collisions,including hidden color phenomena, and ridge production.

1

0258

Intrinsic charm search at the J-PARC high momentum beamlineYuhei Morino1

The existence of |uudcc⟩ Fock components in a proton, which is called ”intrinsic charm”, was suggestedin the early 1980’s[1]. The intrinsic charm tends to have a large momentum fraction (x), unlikely ”extrinsiccharm” which is generated by gluon splitting perturbatively. In addition, parton distribution function (PDF) ofthe intrinsic charm can be different from the PDF of intrinsic anti-charm. These features of the intrinsic charmhave been applied for possible solutions of various unexpected phenomena related to heavy quarks. However,the existence of the intrinsic charm remains still inconclusive, despite a number of experimental and theoreticalstudies to evaluate a probability of the intrinsic charm. Additional experimental results are necessary to confirmthe existence of the intrinsic charm. An identification of a clean and characteristic phenomenon of the intrinsiccharm will be a smoking gun.

The anomalous J/ψ suppression of the yield per nucleon at large xF in high energy hadron-nucleus collisionsis one of the most striking phenomena related with the intrinsic charm[2]. An introduction of ”soft” productionof J/ψ due to the intrinsic charm can account for the anomalous J/ψ suppression intuitively[3]. On the otherhand, the energy loss model, which assumes the color singlet model for J/ψ production and the large energyloss for the color-octet cc pair in the nuclear matter, can also explain the anomalous suppression[4]. Since itis difficult to reject the energy loss model from the experimental results to date, the present J/ψ suppressioncannot be regarded as an evidence of the intrinsic charm.

The energy loss effect of the cc color-octet will become negligible in the case of backward production in lowenergy collisions, since the produced color-octet is slowly moving and then the path length of the octet becomessignificantly short. On the other hand, the intrinsic charm scenario predicts J/ψ suppression at backward regionsas well as the forward J/ψ suppression. Therefore, backward J/ψ suppression in low energy collisions is thecharacteristic phenomenon of the intrinsic charm. The measurement of backward J/ψ production in low energyhadron-nucleus collisions will provide a crucial information for the intrinsic charm.

The measurement of backward J/ψ production in low energy hadron-nucleus collisions can be performed byby using a 30 GeV proton beam at the J-PARC high momentum beamline and the J-PARC E16 spectrometer[5].The J-PARC E16 spectrometer, which has been developed for the study of the mass modification of ϕ mesonin the nuclear matter, can measure backward production of J/ψ. The energy of the proton beam at the highmomentum beam line is significantly lower than previous measurements of J/ψ suppression, which are severalhundred GeV. The cross section of J/ψ via the hard processes gets considerably small in the case of low energycollisions. It leads that the fraction of the contribution from the intrinsic charm increases and backward J/ψproduction gets to be more sensitive to the intrinsic charm. By the above reasons, the measurement of backwardJ/ψ production at J-PARC is suitable for the study of the intrinsic charm.

A model calculation was performed to evaluate the effect of the intrinsic charm on J/ψ production. AGEANT4-based Monte-Carlo simulation was also performed to evaluate the capability of the J-PARC E16spectrometer to measure J/ψ. In this talk, the feasibility of the measurement of backward J/ψ to search theintrinsic charm will be discussed based on the model calculation, the Monte-Carlo simulation and the expectedstatistics.

REFERENCES

[1] S. J. Brodsky, P. Hoyer, C. Peterson, and N. Skai, Phys. Lett. B 93 451 (1980).[2] M. J. Leitch et al., Phys. Rev. Lett 84 3256 (2000).[3] R. Vogt, Phys. Rev. C 61 035203 (2000).[4] F. Arleo and S. Peigne, Phys. Rev. Lett 109 122301 (2012).[5] S. Yokkaichi, Lect. Notes. Phys.C781 161 (2009).[6] Y. Morino et al., J-PARC LOI, http://j-parc.jp/researcher/Hadron/en/pac 1801/pdf/LoI 2018 6.pdf

1Yuhei Morino is with Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization (KEK), Tsukuba,Ibaraki 305-0801, Japan ymorino@post.kek.jp

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0090

Transverse single spin asymmetry for very forward π0

production in polarized p + p collisions at√s = 510 GeV.

Minho Kim∗ for the RHICf collaboration

June 29, 2018

Transverse single spin asymmetry, AN , of very forward (η < 6) π0 production from510 GeV p+ p collisions was measured an newly installed electro-magnetic calorimeter atSTAR experiment in June, 2017. Usually non-zero AN of forward π0 (3 < η < 4) hasbeen measured and described by the partonic structure of the proton in perturbative QCDframework. However, recent data indicates a potential contribution from the diffractiveinteraction rather than partonic one. Here, AN of very forward π0 production will providea new insight on the origin of AN . In this presentation, we’ll report our measurement ofthe very forward π0 and its AN preliminary result over the transverse momentum range of0.0 < pT < 1.0 GeV/c and momentum fraction to proton range of 0.2 < xF < 1.0.

1

0166

Self-organization of atomic nuclei and

prospect for stable superheavy nuclei

Takaharu Otsuka

RIKEN Nishina Accelerator Science Center University of Tokyo

I shall discuss how the interplay between the single-particle states and the collective (shape) modes occurs in atomic nuclei as consequences of certain characteristic features of nuclear forces such as the central and tensor forces. The quadrupole deformation of nuclear shape is determined by the balance between effects of the quadrupole interaction, as the collective-mode driving force, and some resistance power. The resistance power includes not only the pairing force, as traditionally known, but also originates in another source. This is the Effective Single-Particle Energy (ESPE). The ESPEs are nothing but effects of the monopole interaction, and are varied according to occupation numbers. The ESPEs have been shown recently to be optimized for each collective band by choosing most optimum configurations, for instance by taking particular particle-hole excitations. For this mechanism, orbital dependences of the monopole matrix elements are crucial, and the resistance power can be reduced substantially. We shall discuss the 1st order quantum phase transition for Zr isotopes, and multiple 1st order quantum phase transitions in the odd-even staggering in Hg isotopes. Advanced Monte Carlo Shell Model calculation is used then. The underlying mechanism for these phenomena is the quantum self-organization, which can produce distinct consequences with (i) two quantum fluids (protons and neutrons), and (ii) two kinds of forces (the mode-driving force (e.g. quadrupole interaction) and the resistance-control force (e.g. monopole interaction)). I shall further present prospect of the structure of the stable superheavy nuclei, where this mechanism may play decisive roles. Indeed, this mechanism may allocate the stable superheavy nuclei in a deformed region.

0266

1

Radii and binding energies in He and oxygen isotopes: a puzzle for nuclear forces

V. Lapoux * and V. Somà CEA-Saclay, IRFU, DPhN Department of Nuclear Physics, Gif-sur-Yvette F-91191 France

*Corresponding author: V. Lapoux valerie.lapoux@cea.fr

Linking a universal description of atomic nuclei to elementary interactions among their constituents, protons and neutrons has long been and remains one of the fundamental challenges of nuclear physics. If accomplished, such a link would be beneficial for a deep understanding of known nuclei (both stable, naturally existing on earth and unstable, created in laboratories worldwide) and to predict on reliable bases the features of the thousands of yet unobserved ones. Many of the latter will not be, in a foreseeable future, experimentally at reach; yet they are crucial to understand the nucleosynthesis of heavy elements. Moreover, to reach quantitative microscopic reaction approaches, since amplitudes and nucleon nucleus interactions evolve as a function of the size, a simultaneous reproduction of binding energies and radii in stable and neutron-rich nuclei is mandatory, as shown for the Helium isotopes, 4,6,8He [Lap15]. The first steps, to examine the validity of the general theoretical framework built upon ab initio calculations, is to consider the way of expanding the reliability of the calculations in terms of extended isotopic chains, and for various nuclear observables, starting with the ground state properties like masses and radii. The recent success of ab initio calculations has been the understanding of the limits of existence at N=16, for 24O, in the chain of Oxygen isotopes; this was achieved including the contribution of three-nucleon forces [Ots10]. Having masses correctly reproduced, it remains an open question as to how nuclear radii can be reproduced simultaneously. For this purpose, we can test the results proposed by theorists, using various techniques of state-of-the art ab initio calculations, for instance Gorkov- self-consistent Green's Function (GGF) [Som11] and multi-reference in-medium similarity renormalisation group (IM-SRG) [Her13].

The talk will present this systematic study [Lap16] of both nuclear radii and binding energies in (even) oxygen isotopes from the valley of stability to the neutron drip line, with a thorough analysis of the available experimental information of charge and matter radii compared to state-of-the-art ab initio calculations. We show that the combined comparison of measured radii and binding energies with ab initio calculations offers unique insight on input nuclear forces, and the need to use newly developed interaction to improve the description of the radii. We underline the key role played by both specific observables – masses AND radii – to crucially progress in the development of nuclear interactions, and the need to collect systematically the (p,p) scattering data induced by exotic beams, to deduce their matter rms radii via reaction models using nucleon-nucleus microscopic potential approaches.

References.

[Ots10] T. Otsuka, T. Suzuki, J. D. Holt, A. Schwenk, and Y. Akaishi, Phys. Rev. Lett. 105, 032501 (2010). [Lap15] V. Lapoux and N. Alamanos, Eur. Phys. J. A (2015) 51: 91. [Som11] V. Somà, T. Duguet and C. Barbieri, Phys. Rev. C 84, 064317 (2011). [Her13] H. Hergert, S. Binder, A. Calci, J. Langhammer, and R. Roth, Phys. Rev. Lett. 110, 242501 (2013). [Lap16] V. Lapoux, V. Somà, C. Barbieri, H. Hergert, J.D. Holt and S.R. Stroberg, Phys. Rev. Lett. 117, 052501 (2016).

0074

Probing the evolution of nuclear structure and the nuclear force using

reaction spectroscopy with re-accelerated beams of rare isotopes

R. Kanungo1,2 and the IRIS Collaboration

1Saint Mary’s University, Halifax, Canada 2TRIUMF, Vancouver, Canada

The isotopes at the limits of binding in the nuclear landscape offer a wealth of new

information on how nature organizes protons and neutrons in such neutron-proton

asymmetric systems. Exotic forms of nuclei appear whose sub-systems become unbound

with a nucleon removal. These unique quantum systems offer sensitive grounds to

investigate the nuclear force.

This presentation will describe the reaction spectroscopy measurements performed using

the IRIS facility with solid H2/D2 targets at TRIUMF in Canada. The results will illustrate

with examples of 20Mg, 8He and 11Li, how new features of rare isotopes at the drip-lines

appear through their excited states from inelastic scattering and two-neutron transfer

reactions. The rare isotopes also provide sensitive grounds to probe the nuclear force. It

will be shown how the scattering of the drip-line nucleus 10C, exhibits effects of the

nuclear force from a comparison of ab inito calculations with forces from the chiral

effective field theory.

Acknowledgements

The work is supported by NSERC, CFI, Nova Scotia Research and Innovation Trust,

RCNP and the grant-in-aid program of the Japanese government. TRIUMF receives

funding via a contribution through the National Research Council Canada. Computing

support came from the LLNL institutional Computing Grand Challenge Program, Oak

Ridge Leadership Computing Facility at ORNL, the JURECA Supercomputing center,

and from Calcul Quebec and Compute Canada. The work is based in part upon work

supported by the U.S. Department of Energy, Office of Science, Office of Nuclear

Physics.

0190

Gamow-Teller Giant Resonance in 132Sn

M. Sasano on behalf of SAMURAI17 collaboration

RIKEN Nishina Center

Gamow-Teller (GT) transition is one of the basic excitation modes in nuclei.

This transition on unstable nuclei is still not well studied. It is important to

investigate how neutron asymmetry (N-Z)/A is influencing the collectivity of

the GT giant resonance (GTGR) through the study of neutron rich unstable

nuclei. In this talk, we present the results of the measurement of the GTGR in

132Sn. In this work, a new experimental technique was employed to measure

the (p,n) reaction at intermediate energies with an RI beam in inverse

kinematics. A thick target was used to obtain a high luminosity even for RI

beams. Through the missing mass spectroscopy, we extracted the GT transition

strengths up to a high excitation energy including the GTGR. The so-called

Landau Migdal parameter g’ was deduced from the measured GTGR energy in

a similar quality as done in stable nuclei for the first time.

0153

Charge-changing cross section measurements at around300 MeV/nucleon at HIRFL-CSR

Bao-Hua Sun1*, Liu-Chun He1, Guang-Shuai Li1, Wen-Jian Lin1, Chuan-Ye Liu1, Isao

Tanihata1, Satoru Terashima1, Yi Tian1, Jian-Wei Zhao1, Li-Hua Zhu1, Feng Wang1,

Meng Wang1, Xiao-Dong Xu1, Zhong Liu2, Chen-Gui Lu2, Zhi-Yu Sun2, Shi-Tao

Wang2, Xue-Heng Zhang2，Dinh Trong TRAN3

1School of Physics and Nuclear Energy Engineering, Beihang University, Beijing 100191, China

2 Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China

3 Research Center for Nuclear Physics (RCNP), Osaka University.

Recently, precise charge-changing cross section (CCCS) measurements have been

developed as a new and efficient method to study charge-radius of exotic nuclei [1].

Combined with Glauber model, this method has been used to provide charge radii of

the neutron-rich 14Be [2], 12-17B [3], 15-19C [4], 30Ne, 32-33Na [5], and the neutron-deficient25-27Si [6].

Since 2014 we proposed the CCCS program based on the Second Radioactive Ion

Beam Line in Lanzhou (RIBLL2) [7], one of the key components in the Heavy Ion

Research Facility in Lanzhou (HIRFL-CSR) at IMP, China. RIBLL2 was developed

to deliver both the primary and secondary beams at around 300 MeV/nucleon. The

results at this energy region showed some inconsistent with those at other energies.

Several experiments aiming at C-O and Na-S isotopes were performed successfully.

In this contribution, we will present the experimental setup (RIBLL2 beam line and

the newly developed detector system), data analysis, the CCCS results of C, N, Mg

and Al isotopes on C target, and the relevant charge radii.

Corresponding author: bhsun@buaa.edu.cn

Reference:

[1] T. Yamaguchi et al., Phys. Rev. C 82(2010)014609.

[2] S. Terashima et al., Prog. Theor. Exp. Phys. 101D02 (2014).

[3] A. Estradé et al., Phys. Rev. Lett. 113, 132501 (2014).

[4] T. Yamaguchi et al., Phys. Rev. Lett.107,032502 (2011); Kanungo et al., Phys. Rev.

Lett. 117, 102501 (2016).

[5] A. Ozawa et al., Phys. Rev. C 89, 044602(2014).

[6] A. Ozawa et al., Nucl. Phys. A 961, 412(2017).

[7] B. Sun et al., Science Bulletin 63(2018)78.

0119

Measurements of 7Be(n,a)4He and 7Be(n,p)7Li reaction cross sections for Big Bang Nucleosynthesis at CERN/n_TOF A Mengoni†, on behalf of the n_TOF Collaboration‡ † ENEA and INFN Bologna, Italy ‡ www.cern.ch/ntof Neutron induced reactions on 7Be, built up during the early phase of evolution of the Universe, could potentially provide a solution for the 7Li overproduction in the Big Bang nucleosynthesis (BBN), a problem known as the Cosmological Lithium Problem. The cross sections of the (n,a) and (n,p) reactions in a wide neutron energy range have been recently measured at the neutron time-of-flight facility, n_TOF, at CERN [1,2]. New reaction rates have been derived from the experimental data and BBN network calculations have been performed. Results on the 7Li yields during standard BBN calculations will be presented. [1] M Barbagallo et al. (The n_TOF Collaboration), Phys. Rev. Lett. 117, 152701 (2016) [2] LA Damone et al. (The n_TOF Collaboration), Phys. Rev. Lett. 121, 042701 (2018)

Isospin dependence from the entrance channel in projectile-like fission at Fermi energies

E. De Filippo1, P. Russotto2, E.V. Pagano2,3, L. Acosta2,4, L. Auditore1,5, T. Cap6, G. Cardella1, B. Gnoffo1,3, G. Lanzalone2,7, C. Maiolino2, N.S. Martorana2,3,

A. Pagano1, M. Papa1, E. Piasecki8, S. Pirrone1, G. Politi1,3, L. Quattrocchi1,5, F. Rizzo2,3, K. Siwek-Wilczynska9, A. Trifirò1,5 and M. Trimarchi1,5

1) INFN, Sezione di Catania, Catania, Italy2) INFN, Laboratori Nazionali del Sud, Catania, Italy

3) Dipartimento di Fisica e Astronomia, Università di Catania, Italy4) Instituto de Fisica, Universidad National Autonoma de Mexico, Mexico

5) Dipartimento di Scienze MITF, Univ. di Messina, Italy6) National Centre for Nuclear Research, Otwork-Swierk, Poland

7) Università Kore, Enna, Italy8) Heavy Ion Laboratory, University of Warsaw, Poland

9) Faculty of Physics, University of Warsaw, Poland

The reactions 124Xe + 64Zn and 64Ni at 35 A.MeV beam incident energy (InKiIsSy, Inverse Kinematic Isobaric System, experiment) were studied at INFN-LNS with the 4π CHIMERA detector and compared to results of previous studied reactions 124,112Sn + 64,58Ni [1]. We study the IMF production probability and emission mechanism in the projectile-like fission by using, as main observable, the angle between the center of mass velocity of the kinematical recon-structed PLF* respect to the relative velocity of the PLF* break-up fragments. We show that prompt-dynamical emission is enhanced by increasing the projectile and target Isospin content in the entrance channel. It is found that the dynamical emission increases, separately, at the increasing of the projectile and target isospin respectively. Experimental results are compared with the Constrained Molecular Dynamic code CoMD. A new experiment [2] has been ap-proved in order to expand our investigation at lower energies of 20 A.MeV by using CHIMERA coupled with 10 telescopes of the new FARCOS correlator.

REFERENCES

[1] P. Russotto et al., Phys. Rev. C92, 014610 (2015). [2] E.V. Pagano, E. De Filippo, P. Russotto and NewChim collaboration, CHIFAR LNS-PAC proposal.

0030

Nuclear matter radii of Ca isotopes across the neutron magic number N = 28 via interaction cross section measurements

M. TanakaA,B, M. TakechiC, M. FukudaB, A. HommaC, T. SuzukiD, Y. TanakaB, D. NishimuraE, T. MoriguchiF, D.S. AhnG, A.S. AimaganbetovH,I, M. AmanoF, H. ArakawaD, S. BagchiJ, K.-H. BehrK, N.

BurtebayevH, K. ChikaatoC, H. DuB, S. EbataK, T. FujiiD, N. FukudaG, H. GeisselJ, T. HoriB, W. HoriuchiK, S. HoshinoC, R. IgosawaD, A. IkedaC, N. InabeG, K. InomataD, K. ItahashiG, T. IzumikawaL, D. KamiokaF, N. KandaC,

I. KatoD, I. KenzhinaM, Z. KorkuluG, Ye. KukH,I, K. KusakaG, K. MatsutaB, M. MiharaB, E. MiyataC, D. NagaeG, S. NakamuraB, M. NassurllaH, K. NishimuroD, K. NishizukaC, S. OmikaD, K. OhnishiB, M. OhtakeG, T. OhtsuboC, H.J. OngN, A. OzawaF, A. ProchazkaJ, H. SakuraiG, C. ScheidenbergerJ,

Y. ShimizuG, T. SugiharaB, T. SumikamaG, S. SuzukiF, H. SuzukiG, H. TakedaG, Y.K. TanakaJ, T. WadaC, K. WakayamaD, S. YagiB, T. YamaguchiD, R. YanagiharaB, Y. YanagisawaG, K. YoshidaG,

and T.K. ZholdybayevH

AKyushu Univ., BOsaka Univ., CNiigata Univ., DSaitama Univ., ETokyo City Univ., FTsukuba Univ., GRIKEN, HAl-Farabi Kazakh National Univ., IL.N.Gumilyov Eurasian National Univ., JGSI,

KHokkaido Univ., LRI Center Niigata Univ., MINP Kazakhstan, NRCNP

The neutron-rich Ca isotopes have attracted attention from both experimental and theoretical aspects because there are two new doubly magic nuclei 52,54Ca [1,2] as well as well-known traditional ones 40,48Ca. Very recently, nuclear charge radii of 39-52Ca were measured by the optical isotope-shift methods [3]. The measured charge radii increase unexpectedly beyond neutron number N = 28. This growth of charge radii from 48Ca to 52Ca cannot be explained quantitatively with several theoretical calculations [3]. Thus, nuclear radii of Ca isotopes in the vicinity of N = 28 also have received a great deal of attention. On the other hand, nuclear matter radii of Ca isotopes were deduced only for stable nuclei 40,42,44,48Ca by the hadron elastic scattering. In order to understand the evolution of nuclear matter radii in the Ca isotopic chain around N = 28, we measured interaction cross sections σI for 42-51Ca on a carbon target at around 270 MeV/nucleon. The experiment was performed at the RIBF, RIKEN by using the BigRIPS fragment separator. The present data are the first σI data systematically measured along the isotopic chain in the Ca mass region. Based on the Glauber-type calculation with the modified optical limit approximation [4], the root-mean-square matter radii <r2>m

1/2 were deduced. Moreover, the neutron-skin thicknesses from the deduced <r2>m1/2

incorporating the previously measured charge radii were also obtained systematically for the first time. The present results show the significant enhancement of <r2>m

1/2 in the region beyond N = 28. Furthermore, this enhancement of matter radii beyond N = 28 is much larger than that of previously measured charge radii. This enhancement cannot be understood by the loosely bound effect such as a halo structure or the nuclear deformation effect. Within the simple single particle model, the significant core enlargement is required to explain the systematics of present experimental <r2>m

1/2 for 49-51Ca. On the other hand, the mean field calculations qualitatively indicate that the enhancement is due to the rapid increase of surface diffuseness.

[1] F. Wienholtz et al., Nature 498, 346-349 (2013). [2] D. Steppenbeck et al., Nature 502, 207-210 (2013). [3] R. F. Garcia Ruiz et al., Nature Phys. 12, 594-599 (2016). [4] M. Takechi et al., Phys. Rev. C 79, 061601(R) (2009).

0187

Heavy Ion Physics Program in China

Nu Xu Institute of Modern Physics, CAS

Abstract: In this talk, I will review Chinese heavy-ion physics activities, including both domestic and international collaborations. Future project HIAF and its impact on our heavy-ion physics program will be discussed.

0256

In-medium properties of Λ in π−-Induced Reactions at 1.7

GeV/c

Steffen Maurus† 1 2 and Laura Fabbietti 1 2 for the HADES Collaboration

The discovery of a two solar mass neutron star [1]

let to a strong constrain regarding different models of

the equation of state (EOS). While new techniques and

findings [2] further reduce the allowed phase space,

the appearance of hyperons inside neutron stars is

still a discussed topic [3]. Therefore it is essential to

have detailed knowledge on the interaction between

hyperons and (normal) nuclear matter. Of special

interest is thus the lightest hyperon, the Λ baryon,

where only few in-vacuum data exist, while no data

for in-medium is available.

In 2014 a dedicated secondary π− + A ( A = C, W)

campaign was performed with the HADES spectrome-

ter at GSI (Darmstadt) at an incident pion momentum

of 1.7 GeV/c. As pion reactions are believed to happen

very close to the surface of the target nucleus [4], also

the Λ is created close by, traversing the whole nucleus

and therefore form an ideal system to study the Λ in-

medium properties.

Our approaches selects the exclusive channel of π− +

p → Λ + K0 with the associate decay products

(Λ → pπ−, K0 → π+π−) to study their behaviour

in two different nuclear environments.

With the help of the GiBUU transport code, we are

testing different scenarios, in detail the different cou-

*This work was supported by SFB 12581Physik Department, TUM, Garching, Germany2Excellence Cluster ”Universe”, Garching, Germany†steffen.maurus@tum.de

plings of the Λ and K0 to normal nuclear environment.

We will report on the analysis of the collected data and

the comparison to simulations testing the sensitivity on

the in-medium modifications.

REFERENCES

[1] P.B. Demorest, Nature 467, 1081 (2010)G.

[2] B.P. Abbott et al., Phys. Rev. Lett. 119, 161101 (2017)

[3] Tolos L. et al, Astrophys.J. 834, 3 (2017) Tolos L. et al,

Publications of the Astronomical Society of Australia 34, The

Equation of State for the Nucleonic and Hyperonic Core of

Neutron Stars (2017)

[4] Benabderrahmane et al. Phys. Rev. Lett. Bd. 102, 182501

(2009)

0046

Energy and system size dependent charged-particle production mea-sured with ALICE

Patrick Huhn on behalf of the ALICE Collaborationphuhn@ikf.uni-frankfurt.deInstitut für Kernphysik Goethe-Universität Frankfurt, Max-von-Laue Straße 1,60438 Frankfurt am Main, Germany

The ALICE experiment at the LHC is designed to investigate the properties of theso-called Quark-Gluon Plasma (QGP) by studying high-energy pp, p-Pb, Pb–Pband recently for the first time Xe–Xe collisions. Such a hot and dense deconfinedQCD medium (the QGP) is created in collisions of Pb- or Xe-ions at high center-of-mass energies. High energetic quarks and gluons created in the early phase ofthe collision traveling through the plasma loose energy (parton energy loss). Suchmedium effects can be examined by comparing the production of charged particlesin heavy-ion collisions with the production in pp collisions where no medium is cre-ated. This comparison is usually expressed by means of the nuclear modificationfactor RAA, the ratio of the yield in A–A collisions and the yield in pp collisionsscaled by the number of binary collisions.In this talk, we present the analysis of transverse-momentum distributions forprimary charged particles as well as the nuclear modification factors in Pb-Pb col-lisions at √

sNN = 2.76 TeV and 5.02 TeV and in Xe-Xe collisions at √sNN = 5.44

TeV measured with ALICE. In particular, we focus on a comparison of the nuclearmodification factors in Pb-Pb and Xe-Xe collisions to investigate a possible systemsize and energy dependence of RAA.

https://alice-publications.web.cern.ch/node/4190https://alice-publications.web.cern.ch/node/4289

1

0054

Dileptons and direct virtual photons inheavy-ion collisions at STAR

Chi Yang for the STAR Collaboration

A primary goal of relativistic heavy-ion physics is to study the fundamental prop-erties of the created hot and dense medium. This medium is expected to emit ther-mal radiation in the form of dileptons and direct photons. Once produced, dilep-tons and direct photons traverse the medium with minimum interactions. Thismakes them ideal electromagnetic probes of the medium evolution by selectingdifferent kinematics.

In this talk, we will present the recent dilepton and direct virtual photon resultsat STAR. The e+e− pair mass distributions compared to hadronic cocktails andthe direct virtual photon pT spectra compared to model predictions will be shown.These results are derived from the STAR beam energy scan phase I program.In addition, the low-pT e+e− pair production in Au+Au collisions at

√sNN =

200 GeV and U+U collisions at√sNN = 193 GeV will be presented. Physics

implications will be discussed.

1

0110

Nuclear reaction study for long-lived fission products in high-level

radioactive waste: Cross section measurements for proton- and deuteron-

induced spallation reactions of long-lived fission products

H. Wang for ImPACT-RIBF collaboration

RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan

Management of high-level radioactive waste from the spent fuel is one of the major issues for the use

of a nuclear power plant. As a promising solution, research and development has been devoted to the

partitioning and transmutation technology where long-lived nuclides are converted to stable or short-

lived ones. In particular, the transmutation on the long-lived fission products (LLFPs) has received

much attention because the LLFP nuclei have large radiotoxicities and they can be produced

continuously in the accelerator driven systems and next-generation nuclear reactors. However,

experimental reaction data for LLFP nuclei are very limited. Nuclear physics plays an essential role

in addressing the treatment on LLFP, because the reliable reaction data and models are necessary for

LLFP reactions.

Aiming at bringing a new invention to the nuclear transmutation on LLFP, we have systematically

studied on the proton- and deuteron-induced spallation for the long-lived fission products 137Cs, 90Sr

and 107Pd at different reaction energies using the inverse kinematics technique. Our study on 137Cs and

90Sr is the first attempt in the history of nuclear physics to solve the problem of the LLFP transmutation

and has triggered the reaction studies for other long-lived fission products.

The experiments were performed at the RIKEN Radioactive Isotope Beam Factory. Cross

sections on proton/deuteron were successfully obtained for these three nuclei. By comparing the

results on proton and deuteron at different energy, the newly obtained data revealed valuable

information on the reaction mechanism. In addition, the cross sections were compared with the

reaction model including both intra-nuclear cascade and evaporation processes. In the presentation,

the cross-section results for LLFP nuclei 137Cs, 90Sr and 107Pd as well as the potential of spallation

reaction on the LLFP transmutation will be discussed.

This work was supported and funded by the ImPACT program of Council for Science,

Technology and Innovation (Cabinet Office, Government of Japan).

0138

Using the Trojan Horse Method to discern α0 andα1 channels for the 10B(n,α)7Li reaction

R. Sparta 1, C. Spitaleri 1,2, G.G. Rapisarda1, A. Cvetinovic1, L. Lamia2, S. Cherubini 1,2, G.L. Guardo 1, M. Gulino 1,3, M. La Cognata1, R.G.

Pizzone1, S. Romano 2, M.L. Sergi 1, A. Tumino1,3

1 INFN Laboratori Nazionali del Sud, Catania, Italy2 Dipartimento di Fisica e Astronomia - Universita di Catania,

Catania, Italy3 Universita’ degli Studi di Enna Kore, Enna, Italy

The Trojan Horse Method has been applied to obtain informations onthe 10B(n,α)7Li excitation function, that is among the most importantneutron induced reaction, mainly because of its use in the medical field.It is also a reference reaction among the neutron induced ones, that iswhy its cross section must be known in very precise way [1]. This reactionhave already been approached via the Trojan Horse Method [2] [3], usingthe deuteron as a virtual source of neutrons, continuing the experimentalTrojan Horse campaign for neutron involving reactions [3] [4] [5].

A new Trojan Horse measurement of the 10B(n,α)7Li reaction hasbeen performed, where for the first time the α1 contribution (comingfrom the first 7Li excited level at 478 keV) to the cross section has beendiscerned from the ground state avoiding the use of gamma ray detection,in the energy region from 0 to 1.2 MeV, the most relevant for all theapplications.

[1] F.J. Hambsch et al., Journal of Physics: Conference Series 205 (2010)012049[2] R.E. Tribble et al., Rep. Prog. Phys. 77 (2014)[3] L. Lamia et al., Nuovo Cimento C31, 423 (2008)[4] M. Gulino et al., J. Phys. G37, 125105 (2010)[5] M. Gulino et al. Phys Rev C87 (2013) 012801(R)

1

0097

Analysis of the 16O(p,pn)15O reaction using the CDCC method

D. Ichinkhorloo 1, M. Aikawa 2, S. Chiba 3,4, Y.Hirabayashi 5, and K. Katō 1

1Nuclear Reaction Data Centre, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan 2Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan

3Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, Tokyo 152-8550, Japan 4National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588, Japan 5Information Initiative Center, Hokkaido University, Sapporo 060-0811, Japan

The study of 16O(p,pn)15O reaction is applicable to on-line PET (positron emission therapy) and

nuclear reaction data fields. However, the experimental data show a discrepancy and a reliable

theoretical calculation is desired.

The continuum-discretized coupled-channel method (CDCC) method is a promising

approach for nuclear reactions involving light nuclei which have a cluster structure. In the

previous works [1-4], we have successfully studied reaction data for the 6,7Li + n elastic and

inelastic scattering angular distributions and neutron spectra applying the CDCC method [5]

with α + d + n and α + t + n models.

In this work, we extended the CDCC analysis to the different target of 16O with wide incident

proton energies up to 100 MeV. We calculate the reaction cross sections of 16O(p,pn)15O using 15N + p + p and 15O + n + p models with the CDCC method in which the model parameters are

fixed for the elastic angular distribution of 16O+p. We compare the calculated results with the

experimental data [6-9].

References

[1]. T. Matsumoto, D.Ichinkhorloo, Y.Hirabayashi, K.Katō, and S.Chiba, Phys. Rev. C 83, 064611, (2011)

[2]. D.Ichinkhorloo, T.Matsumoto, Y.Hirabayashi, K.Katō and S.Chiba, J. Nucl. Sci. Technol. Vol.48, No. 11, pp. 1357-1460 , Sep. 2011

[3]. D.Ichinkhorloo, Y.Hirabayashi, K.Katō, M. Aikawa, T.Matsumoto, and S.Chiba, Phys. Rev. C 83,064604, (2012)

[4]. D.Ichinkhorloo, M.Aikawa, S.Chiba, Y.Hirabayashi and K.Kato, Low energy scattering cross sections for n +6,7Li reactions using the continuum-discretized coupled-channels method, Phys.Rev.C 93, 064612, 2016

[5]. M.Kamimura, M.Yahiro, Y.Iseri, Y.Sakuragi, H.Kameyama and M.Kawai, Prog. Theor. Phys. Suppl. No. 89 (1986)

[6]. T.Masuda et al., Scientific Reports, 8 (2018) 2570 [7]. T.Akagi et al., Radiation Measurements 59 (2013) 262-269 [8]. M.Sajjad et al., RCA,38,57,1985 [9]. M.G.Albouy et al., PL,2, 306,1962

0188