Abstract book: Parallel­3

Parallel-3

A-3116A12A96A124A170A

B-2217B66B73B60B177B

C1-3130C144C134C40C111C186C

C2-399C75C95C101C24C44C

D-353D33D127D37D137D32D

E-3255H58E84E140E47E179E

JK-1173J203H196J43J

Quasifission and fusion probabilities in tip collisions with deformed actinide nuclei D.J. Hinde, M. Dasgupta, D.Y. Jeung, C. Simenel, E.C. Simpson, E. Prasad, E. Williams, K. Banerjee,

T. Banerjee, L. Bezzina, I.P. Carter, K.J. Cook, R. Jain, C. Sengupta, B.M.A. Swinton-Bland

Department of Nuclear Physics, RSPE, ANU, Canberra, Australia

The formation of superheavy elements (SHE) by fusion of two nuclei is reduced by (i) suppression of fusion by faster non-equilibrium processes such as quasifission and (ii) by fission following fusion. Low excitation energies favour SHE survival against fission, so in “cold” fusion with spherical target nuclei near 208Pb, SHE yields are largest at beam energies significantly below the average capture barrier. However this is not true in “hot” fusion with statically deformed actinide nuclei. Here the elongated deformation-aligned configurations in sub-barrier capture reactions (sketched in Fig.1(c), red projectile) suppress fusion, resulting in re-separation by quasifission. Could SHE still be formed in sub-barrier reactions? Can the fusion inhibition be quantified?

The Australian National University Heavy Ion Accelerator Facility and CUBE fission spectrometer have been used to measure fission and quasifission mass and angle distributions (MAD) for reactions with projectiles from C to S, bombarding Th and U target nuclei, to address this question (as recently published in Ref.[1]).

Mass-asymmetric fast quasifission (FQF), highlighted by the pink box in Fig.1(a), is associated with collisions with the tips of the prolate actinide nuclei. Its deduced probability [1] shows a rapid increase with increasing projectile charge, the transition being centred around projectile atomic number ZP=14 (Fig.1(d)). For mass-symmetric fission (green box in Fig.1(a)), deviations of angular anisotropies from expectations for fusion-fission (Fig.1(e)), indicate a component of slower (mass-symmetric) quasifission (SQF). The inferred slow quasifission fraction FSQF shows a transition around ZP=8, indicated in Fig.1(d) by the green symbols and line.

From this and associated work [2], collisions with the tips of statically deformed prolate actinide nuclei show two distinct quasifission processes, with different time scales. The probabilities of both increase rapidly with projectile charge. The probability of fusion at sub-barrier energies can be severely suppressed by these two quasifission processes, since the heavy element yield should be determined by the product of the probabilities of surviving each quasifission process. Fig.1(d) shows this probability should be small for heavy projectiles.

Fig.1. Quasifission in sub-barrier actinide collisions. For 34S+232Th measured at 0.95 of the capture barrier energy VB, the mass-angle distribution is shown in (a) and the mass-ratio (MR) projection in (b). Highlighted in pink is mass-asymmetric fast quasifission (FQF), which is associated with collisions with the tips of the deformed 232Th (see sketch c). The beam energy dependence of the asymmetric to symmetric cross sections gives information on the fast quasifission probability PFQF as shown vs. projectile atomic number ZP in (d). Angular distributions of the mass-symmetric fission (highlighted in green in (a) and (b)) give anisotropies (e) higher than those calculated for fusion-fission (curves in (e)). The fractions of slow quasifission (FSQF) at 0.96VB for each reaction shown in (e) are then inferred for tip collisions, as presented in (d) by green symbols.

1) D.J. Hinde et al., Phys. Rev. C97 (2018) 0246162) E. Prasad et al., Phys. Rev. C93 (2016) 024605

0116

CDCC calculations of total fusion of projectiles 6Li and 7Li with targets28Si, 59Co, 96Zr, 144Sm and 209Bi: Effect of resonance states

A. Gomez Camacho1

Abstract—CDCC calculations [1]-[3] of total fusion crosssections for reactions induced by the weakly bound nuclei[4] 6,7Li with targets 28Si, 59Co, 96Zr, 144Sm and 209Bi atenergies around the Coulomb barrier are presented. In thecluster structure frame of 6Li→ α + d and 7Li→ α + t , short-range absorption potentials are considered for the interactionsbetween the α-, d- and t-fragments with the targets. Theeffect of resonance states of 6Li (l = 2,Jπ = 3+,2+,1+) and7Li (l = 3,Jπ = 7/2−,5/2−) on fusion is studied by using twoapproaches: (1) by omitting the resonance states from the fulldiscretized CDCC breakup space and 2) by considering only theresonance sub-space [5]-[8]. A systematic analysis of the effecton fusion from resonance breakup couplings is carried out fromlight to heavy mass targets. Among other things, it is found thatresonance breakup states produce strong repulsive polarizationpotentials that lead to fusion suppression while couplings fromnonresonance states give place to weak repulsive potentials athigh energies, however these become attractive for the heaviertargets at low energies. As a matter of fact, the particular effectsof a given resonance on fusion are also studied as Fig.1 shows.An interpretation of these effects shall be given in terms of themean-half lives of the resonances.

Fig. 1. The solid-line corresponds to total fusion calculated with thefull discretized space. The long-dashed line to the resonance sub-space.The short-dashed line to the case when the 3 +-resonance is extracted fromthe resonance sub-space. The dotted-line when the 1 + is extracted and thedashed-dotted-line when the 2 + is not included.

1A. Gomez Camacho is a Nuclear Physics Researcher at the Depar-tamento del Acelerador, Instituto Nacional de Investigaciones Nucleares,Apartado Postal 18-1027, C.P. 11801 Mexico, Distrito Federal, Mexicoarturo.gomez@inin.gob.mx

REFERENCES

[1] Y. Sakuragi, M. Yahiro, M. Kamimura, Prog. Theor. Phys. Suppl., 89,1 (1986)

[2] Y. Sakuragi, M. Yahiro, M. Kamimura, Prog. Theor. Phys. 70, 1047(1983)

[3] N. Austern, Y. Iseri, M. Kamimura, et al., Phys. Rep., 154, 125 (1987)[4] L.F. Canto, P.R.S. Gomes, R. Donangelo, M.S. Hussein, Phys. Rep.

424, 1 (2004)[5] A. Gomez Camacho, A. Diaz-Torres, P.R.S. Gomes, J. Lubian, Phys.

Rev. C, 91, 014607 (2015)[6] A. G. Camacho, A. Diaz-Torres, P.R.S. Gomes, J. Lubian, Phys. Rev.

C, 93, 024604 (2016)[7] A. Gomez Camacho, J. Lubian, H.Q. Zhang, et al., Chinese Phys. C,

41, 124103 (2017)[8] Alexis Diaz-Torres and Daanish Quraishi, Phy. Rev. C 97, 024611

(2018)

0012

Resonant breakup of 7Li in 112Sn(7Li,7Li*→α+t) reaction

D. Chattopadhyay1,2*, S. Santra1,2, A. Pal1,2, A. Kundu1,2, K. Ramachandran1,R. Tripathi2,3,

B.J.Roy1,2, T.N. Nag2,Y.Sawant1, B.K.Nayak1,2, A.Saxena1,2 and S. Kailas1

1Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai - 400085, INDIA, 2Homi

Bhabha National Institute, Anushakti Nagar, Mumbai 400094, India , 3Radiochemistry Division,

Mumbai 400085, India

Study of projectile breakup in the field of

target nucleus is a burning topic, particularly

due to recent advent in the availability of

weakly bound exotic beams. Measurement of

breakup of 7Li into α + t via its first resonance

state (7/2-, 4.63 MeV) is available in literature

for a few systems. However, there is no

measurement available for its breakup via

second resonance state i.e., 5/2- (6.67 MeV).

The importance of this state is however

remarkable as various studies on elastic

scattering show a very significant effect of

coupling of this resonance state of 7Li [1, 2].

Therefore, exclusive measurements have

been carried out at beam energy of 30 MeV

using the experimental set-up similar to

Ref.[3]. From the efficiency corrected relative

energy distribution of α + t breakup as shown

in Fig. 1, it is observed that apart from the

direct breakup at low energy there are two

dominant peaks at 2.23 MeV and 4.28 MeV

which correspond to first and second resonance

states at 7/2− (4.63 MeV) and 5/2− (6.67 MeV).

The comparison of the peak positions and

widths of resonance states with the literature

values actually confirms the observation of 7Li

breakup into α + t via its 5/2− resonance state

for the first time along with 7/2− resonance

and direct breakup. Differential cross-sections

for 7Li→α + t breakup via its two resonance

states 7/2−, 5/2− were also measured and

compared with the Coupled Channel

calculations as shown in Fig.2.

Fig.1: Efficiency corrected relative energy distribution

References:

1. K. Rusek et al., PRC 67, 014608 (2003).

2. W. Ott et al., NPA 489, 329 (1988).

3. D. Chattopadhyay et al., Phys. Rev. C 94, 061602 (R), (2016).

Fig.2: Angular distributions of direct and sequential

breakup cross sections for 7Li→α+t. The solid (blue),

dashed (green) and dashed-dot (pink) lines represent the

CDCC calculations corresponding to 7/2- resonance state,

5/2- resonance state and direct breakup of 7Li

respectively.

Erel (MeV)

0 2 4 6 8C

ou

nts

0

2000

4000

6000

8000

7Li(7/2-,4.63MeV)

direct

7Li(5/2-,6.67 MeV)

c.m.

(degree)40 60 80 100 120

d

br.

/d

(m

b/s

r)

0.0

0.1

0.2

0.3

0.4

0.5

0.67Li(7/2-)-->+t (res.)7Li(5/2-)-->+t (res.)

7Li-->+t (direct)

0096

Role of octupole deformed shell effects on the fission of nuclei in the mercuryregion

Guillaume Scamps∗

Center for Computational Sciences, University of Tsukuba, Tsukuba 305-8571, Japan

Cedric Simenel†

Department of Theoretical Physics and Department of Nuclear Physics, Research School of Physics and EngineeringAustralian National University, Canberra, Australian Capital Territory 2601, Australia

The common interpretation of the origin of massasymmetric fission in actinides involves sphericalshell effects expected to favour the formation of aheavy fragment in the 132Sn region. The discoverythat 180Hg fission is mass asymmetric instead of be-ing symmetric with two semi-magic 90Zr fragmentsthen came as a surprise [1]. Many theoretical andexperimental investigations have been dedicated toinvestigate this phenomenon.

However, recent fully microscopic dynamical cal-culations based on the Time-Dependent BCS (TD-BCS) approach [2] have demonstrated the impor-tance of octupole deformation in the fission frag-ments [3]. These calculations show that fission frag-ments with strong octupole correlations are favouredand that such correlations in the 144Ba region [4] maywell be at the origin of mass asymmetric fission inactinides.

178Hg

182Hg

184Hg

186Hg

188Hg

188HgSym.

Z=44N=57

Z=44N=56

Z=45N=59

Z=45N=56

Z=46N=62

Z=40N=54

Z=35N=42

Z=36N=46

Z=36N=47

Z=35N=47

Z=34N=46

FIG. 1. Isodensity surfaces and neutron localisationfunctions in mercury isotopes at scission.

In the present contribution, we investigate withthe TDBCS approach the effect of quadrupole andoctupole deformations on the fission asymmetry ofelements around 180Hg. Figure 1 shows isodensitiy

FIG. 2. TDBCS prediction of the fission fragments (redcircles) of mercury isotopes (blue crosses).

surfaces of the fissioning mercury isotopes in theirmass asymmetric valley just before scission. Theprojection below the 3D surface shows the neutronlocalisation function from which quantum shell sig-natures can be investigated. The resulting massasymmetry in the fragments is clearly correlatedwith Z = 34 in the light fragment and in some caseswith N = 56 in the heavy fragment (see Fig. 2).Both numbers are associated with deformed shellgaps with a combination of octupole and quadrupole(prolate) deformations. This shows that mass asym-metric fission in the mercury region is due to oc-tupole (and quadrupole) correlations in a similar wayas in the actinide region.

∗ scamps@nucl.ph.tsukuba.ac.jp† cedric.simenel@anu.edu.au

[1] A. N. Andreyev, Phys. Rev. Lett. 105, 252502 (2010).[2] G. Scamps, C. Simenel, and D. Lacroix, Phys. Rev.

C 92, 011602(R) (2015).[3] G. Scamps and C. Simenel, arXiv preprint

arXiv:1804.03337 (2018).[4] B. Bucher, Phys. Rev. Lett. 116, 112503 (2016).

0124

IMFs production in the reactions78,86Kr+40,48Ca at 10 AMeV

B.Gnoffo1,2, S. Pirrone1, G. Politi1,2, E. De Filippo1, P.

Russotto3, M. Trimarchi1,4, L. Auditore1,4, C. Beck5, G.

Cardella1, F. Favela1, G. Lanzalone3,6, N.S. Martorana2,3, A.

Pagano1, E.V. Pagano3, M. Papa1, E. Piasecki7, L.

Quattrocchi1,2, F. Rizzo2,3, A. Trifirò1,4.

1)INFN, Sezione di Catania, Catania, Italy

2)Dipartimento di Fisica e Astronomia,Università di Catania, Catania, Italy

3)INFN, Laboratori Nazionali del Sud, Catania, Italy

4)Dipartimento di Scienze Matematiche e Informatiche,Scienze Fisiche e

Scienze della Terra, Università di Messina, Messina, Italy

5)Institute Pluridisciplinaire Hubert Curien, Universite de Strasbourg,

CNRS-IN2P3, Strasbourg, France

6)Università degli Studi di Enna,“Kore”, Enna, Italy

7)Heavy Ion Laboratory, University of Warsaw, Warsaw, Poland

The reactions 78Kr+40Ca and 86Kr+48Ca have been realized at

10 AMeV at Laboratori Nazionali del Sud in Catania with the

4π multidetector CHIMERA.

The reaction mechanisms involved in these collisions populate

a wide range of the mass region from light charge particles up

to fission fragments and evaporation residues; between these

two extremes a strong production of Intermediate Mass

Fragments (Z>=3) have been observed.

Fusion-fission like processes and the break-up of the Projectile-

Like (PLF) into two fragments following more violent deep-

inelastic collision, are the two principal processes through

which the IMFs are produced.

A selection method has been developed, in order to

discriminate among the different reaction mechanisms that

populate the same region of the phase-space.

The isospin degree of freedom plays a crucial role, in particular

in fission-like processes, in which the production cross sections

of each single Z are systematically higher for the system 78Kr+40Ca respect to 86Kr+48Ca one.

Besides the PLf break-up mechanism shows a most probable

PLF aligned break-up, along the direction of the PLF-TLF

separation axis, with the light fragment emitted in the backward

part, suggesting dynamical-non equilibrium effects.

0170

MRTOF Mass Spectrographs at RIKEN RIBF ---toward comprehensive mass measurements of >1000 nuclides including super

heavy nuclides---

Michiharu Wada for the SHE-Mass Collaboration, Wako Nuclear Science Center, Institute of Particle and Nuclear Studies, KEK

Abstract: The exotic isotopes 249-253Md [1] as well as many other rare isotopes of heavy- [2,3] and intermediate-mass nuclei [4] – 80 isotopes in total – have successfully been measured with a multi-reflection time-of-flight mass spectrograph (MRTOF-MS) at the GARIS-II facility of RIKEN RIBF in 2016-2017. In the series of experiments, we showed that the mass spectrograph can precisely and accurately measure atomic masses with high efficiency even for very short-lived isotopes having a half-life of 10 ms. After successful completion of the first campaign, we are expanding to have mass spectrographs at multiple facilities of RIBF such as the new GARIS-II, KISS, and BigRIPS+SLOWRI, to perform comprehensive mass measurements of all available nuclides at RIBF. The flagship experiment will be for hot-fusion superheavy nuclides, in particular 288Mc and 284Nh. In this talk, we review the present status and discuss the ongoing projects and future prospects.

[1] Y. Ito et al., Phys. Rev. Lett. 120, 102501 (2018) [2] M. Rosenbusch et al., Phys. Rev. C 97, 064306 (2018) [3] P. Schury et al., Phys Rev. C 95, 011305R (2017) [4] S. Kimura et al., Int. J. Mass Spectom. 430, 134-142 (2018)

Schematic view of the MRTOF Mass Spectrograph at GARIS-II facility of RIKEN RIBF

0217

Barrier distribution for fusion to synthesize superheavyelements: role of static deformation of a target nucleus

K. Hagino1 and T. Tanaka2, 3

1Department of Physics, Tohoku University, Sendai 980-8578, Japan2RIKEN Nishina Center for Accelerator-Based Science, Wako 351-0198, Japan

3Department of Physics, Kyushu University, Fukuoka 819-0395, Japan

In heavy-ion fusion reactions at energies around the Coulomb barrier, excitations of low-lying collective motions play an important role [1, 2]. Such excitations lead to a distribution offusion barriers, which has a responsibility to enhance fusion cross sections below the Coulombbarrier as compared to a prediction of a simple potential model [1, 3]. The fusion barrier distri-bution can actually be extracted from measured fusion cross sections, taking the second energyderivative of the product of the incident energy and fusion cross sections, which has been per-formed experimentally for many systems [3]. The extracted fusion barrier distributions haverevealed that the barrier distribution is sensitive to the channel couplings, thus providing a fin-ger print of the underlying dynamics of fusion reactions.

Recently, this technique has been applied to a system relevant to superheavy nuclei, that is,the 48Ca+248Cm system [4]. The coupled-channels analysis for the measured barrier distribu-tion, which takes into account the deformation of the target nucleus 248Cm, has clearly shownthat the maximum of the evaporation residue cross sections for this system appears at an energyslightly above the barrier height for the side collision, in good agreement with the notion ofcompactness for a compound nucleus formation [5].

In this contribution, we will discuss the significance of barrier distributions for syntheses ofsuperheavy elements, by presenting the coupled-channels analysis for the 48Ca+248Cm system.We will particularly discuss the role of deformation and orientation of the target nucleus usingthe extended version [6] of fusion-by-diffusion model of Swiatecki et al.. A systematic analysiswith this model for several hot fusion reactions will also be presented.

[1] K. Hagino and N. Takigawa, Prog. Theo. Phys. 128, 1061 (2012).[2] K. Hagino, N. Rowley, and A.T. Kruppa, Comput. Phys. Comm. 123, 143 (1999).[3] M. Dasgupta, D.J. Hinde, N. Rowley, and A.M. Stefanini, Annu. Rev. Nucl. Part. Sci. 48, 401 (1998).[4] T. Tanaka et al., J. Phys. Soc. Jpn. 87, 014201 (2018); contribution to this conference.[5] D.J. Hinde et al., Phys. Rev. Lett. 74, 1295 (1995).[6] K. Hagino, Phys. Rev. C, in press; arXiv:1803.02036.

0066

Fusion Dynamics for Hot Fusion Reactions revealed inQuasielastic Fusion Barrier Distributions

T. Tanaka1,2, K. Morita1,2, K. Morimoto1, D. Kaji1, H. Haba1, R. A. Boll3, N. T. Brewer3, S. Van Cleve3,D. J. Dean3, S. Ishizawa1,4, Y. Ito1, Y. Komori1, K. Nishio5, T. Niwase1,2, B. C. Rasco3, J. B. Roberto3,

K. P. Rykaczewski3, H. Sakai1, D. W. Stracener3, and K. Hagino6,7

Studying the barrier distributions of heavy-ion reactionsystems provides important information on the nucleus-nucleus potential near the Coulomb barrier[1]. In heavy-ion reaction systems, the barrier is strongly modified bycouplings of the relative motion between colliding nuclei toseveral nuclear excitations[1], as well as to nucleon trans-fer channels[2]. These couplings replace a single Coulombbarrier with a multitude of barriers. Such dynamical prop-erties of heavy-ion reactions can be studied by experimen-tally extracting so-called barrier distributions from excitationfunctions. The barrier distribution is obtained from eitherfusion reactions[3] or quasielastic (QE) scattering[4], whichis defined as the sum of all reaction processes other thanfusion (i.e, elastic scattering, inelastic scattering, and directtransfer channels). In this work, we used the method ofderiving the barrier distribution from QE scattering events.

In the quest for undiscovered nuclei, information on theincident energy that gives the maximum evaporation residuecross section is essential. In the Ref. [5], the barrier distribu-tion for the reaction 48Ca+248Cm has been measured, whichhas clarified that the evaporation residue (E.R.) cross sectionsfor 48Ca+248Cm are enhanced at energies corresponding toa compact collision geometry with the projectile impactingthe side of the deformed target nucleus.

To clarify the fusion dynamics for hot fusion reactions, wefurther measured the excitation functions of QE scatteringcross sections σQE relative to the Rutherford cross sectionsσR for 22Ne+248Cm, 26Mg+248Cm, and 48Ca+238U systems.In contrast to previous QE barrier distribution studies[6], [7]which measured the recoiled projectile nuclei at back side(θ ∼ 170◦), this work could measured the QE scatteringcross section for l = 0 by measurement of the target nucleiwhich recoiled at completely forward side with using thegas-filled-type recoil ion separator GARIS. The quasielasticscattering events were clearly separated from deep-inelastic

1RIKEN Nishina Center for Accelerator-Based Science, Saitama 351-0198, Japan

2Department of Physics, Kyushu University, Fukuoka 819-0395, Japan3Oak Ridge National Laboratory, Tennessee 37831, United States4Graduate School of Science and Engineering, Yamagata University,

Yamagata 990-8560, Japan5Advanced Science Research Center, Japan Atomic Energy Agency,

Tokai, Ibaraki 319-1195, Japan6Department of Physics, Tohoku University, Sendai 980-8578, Japan7Research Center for Electron Photon Science, Tohoku University, Sendai

982-0826, Japan

events by using GARIS and its focal plan detectors. Thequasielastic barrier distributions were successfully extracted.

The comparison of the experimental barrier distributionswith results of coupled-channels calculations[8], clearlyshows that the barrier distributions were strongly affectedby the deformation of the target nucleus. In addition, thebarrier distributions were influenced by vibrational and ro-tational excitations of the colliding nuclei. Comparing thepeak of the E.R. cross sections σE.R. with the experimentalaverage Coulomb barrier height B0, we found that the peaksappear well above the B0 in the barrier distributions. Thisindicates that the E.R. cross sections are largely determinedby using the advantage of the compact collision. In thecompound nucleus (CN) formation process, the probabilityof CN formation increases for side collision because ofthe shorter distance of the center of nuclei in the touchingconfiguration. Moreover, increasing the fusion hindrance,such as 48Ca+248Cm (Z1Z2 = 1920), the peak of the σE.R.

is close to the Coulomb barrier of side collision Bside.A few experimental groups will attempt (have attempted)

to syntheses new elements Z > 118 by using the com-binations of the 50Ti, 54Cr projectiles with 248Cm, 249Bk,249−251Cf targets, in hot fusion reaction[9], [10], [11]. Inthat case, our study strongly implies that the incident energyof maximum σE.R. will appear at the energy of Bside.

The experiments of this study were performed at the RIBeam Factory operated by RIKEN Nishina Center and CNS,University of Tokyo. We would like to thank the acceleratorstaff for their excellent operation and assistance during theexperiments. In particular, we are grateful to Dr. M. Kiderafor providing stable beams and RILAC accelerator operatorsfor managing several fast energy changes during the nightand day. 248Cm material was provided by the U.S. DOEIsotope Program.

REFERENCES

[1] M. Dasgupta, et. al., Ann. Rev. Nucl. Sci. 48, 401(1998).[2] A. B. Balantekin, et. al., Rev. Mod. Phys. 70, 77 (1998).[3] N. Rowley, et. al., Phys. Lett. B 254, 25 (1991).[4] H. Timmers, et. al., Nucl. Phys. A 584, 190 (1995).[5] T. Tanaka, et. al., J. Phys. Soc. Jpn. 87, 014201 (2018).[6] S. Mitsuoka, et. al., Phys. Rev. Lett. 99, 182701 (2007).[7] S. S. Ntshangase, et. al., Phys. Lett. B 651, 27 (2007).[8] K. Hagino, et. al., Comput. Phys. Commun. 143, 123 (1999).[9] S. Dmitriev, et. al., EPJ Web of Conf. 131, 08001 (2016).

[10] C. E. Dullmann, EPJ Web of Conf. 131, 08004 (2016).[11] S. Hofmann, et. al., Eur. Phys. J. A 52, 180 (2016).

0073

The study of the population of neutron-rich heavy nuclei located along the neutron closed shell N=126 (in the mass region A~200) is crucial for understanding the shell evolution far from the stability and testing theoretical models that provide predictions for the synthesis of heaviest nuclei through the r-process path. The multinucleon transfer (MNT) process in heavy-ion collisions around the Coulomb barrier has been indicated as a promising mechanism for the population of neutron-rich heavy nuclei [1][2], complementary to the projectile fragmentation in inverse kinematics reactions at relativistic energies [3]. The difficulties concerning the identification of the heavy partner in MNT with the present experimental techniques did not allow precise measurements of its production yields and a complete understanding of the reaction mechanism. Moreover, secondary processes, such as particle evaporation and fission, may affect in a non-negligible way the final yields when heavy nuclei are involved. In some recent experiments the study of the mechanism and the probability for the production of neutron-rich heavy nuclei with MNT reactions was attempted by employing either γ-particle coincidence [4], high-efficiency but low-resolution particle-particle coincidences [5] or radiochemical methods [6].

In this context, a benchmark experiment was carried out at LNL, aiming to measure the yields of light and heavy fragments populated in the inverse kinematics reaction 197Au+130Te at Elab=1.07 GeV via MNT processes, by using the kinematic coincidence technique [7]. The inverse kinematics method allowed to get a high detection efficiency and good mass and nuclear charge resolutions (for the Te-like fragments). In particular, in this experiment we exploi-ted the performance of the large acceptance spectrometer

PRISMA to identify, with high resolution isotopes, in the tellurium region, while the coincident Au-like partners were detected with a dedicated set-up [8] specially built for PRISMA. Mass and charge of the light reaction partner were obtained through an event-by-event trajectory reconstruction in PRISMA. The extracted cross sections for neutron transfer channels were compared with the ones calculated with the GRAZING code. Assuming a binary character of the reaction, the kinematic coincidence allowed to determine the mass of the heavy partner. In particular, for each Te isotope identified in PRISMA the coincident mass distribution of the heavy partners was obtained through a mass-mass correlation matrix. Comparing these mass distributions with those obtained with Monte Carlo simulations of the scattering process and the subsequent de-excitation, we could quantitatively infer about the behavior of the heavy partner and the contribution of evaporation effects on the population of neutron-rich heavy nuclei.

The talk will focus on the main results as well as the developments carried out around the target area of PRISMA, with emphasis on the importance for future investigations in heavy mass regions also with radioactive ion beams.

REFERENCES [1] L. Corradi, G. Pollarolo, and S. Szilner, J. Phys. G: Nucl. Part. Phys. 36,

113101 (2009). [2] V. Zagrebaev and W. Greiner, Phys. Rev. Lett. 101, 122701 (2008). [3] T.Kurtukian-Nieto et al., Phys. Rev. C89, 024616 (2014). [4] Y. X. Watanabe et al., Phys. Rev. Lett. 115, 172503 (2015). [5] E. M. Kozulin et al., Phys. Rev. C. 86, 044611 (2012). [6] J. V. Kratz et al., Phys. Rev. C 88, 054615 (2013). [7] F. Galtarossa et al., Phys. Rev. C 97, 054606 (2018). [8] E. Fioretto et al., Nucl. Instr. Meth. Phys. Res. A 899, 73 (2018).

Study of the multinucleon transfer channels in the 197Au+130Te reaction through a high-resolution kinematic coincidence

E. Fioretto, L. Corradi, F. Galtarossa, A.M. Stefanini and J.J. Valiente-Dobón Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali di Legnaro, Legnaro, Italy

G. Colucci, A. Goasduff, D. Mengoni, G. Montagnoli, D. Montanari, F. Scarlassara and E. Strano Università di Padova, and Istituto Nazionale di Fisica Nucleare, Padova, Italy

S. Szilner, T. Mijatović, P. Colović, D. Jelavić Malenica, M. Milin, N. Skukan and N. Soić Ruđer Bošković Institute Zagreb, Croatia

Y.X. Watanabe and S. C. Jeong Institute of Particle and Nuclear Studies, KEK, Tsukuba, Ibaraki, Japan

G. Pollarolo Università di Torino, and Istituto Nazionale di Fisica Nucleare, Torino, Italy

S. Courtin, G. Fruet and F. Haas IPHC, CNRS-IN2P3, Université de Strasbourg, Strasbourg, France

D. Ackermann GANIL, CEA/DSM-CNRS/IN2P3, Caen, France

J. Grebosz The Henryk Niewodniczanski Institute of Nuclear Physics, Krakow, Poland

0060

Barrier distribution measurement for a system with actinide target

Gurpreet Kaur1,2, B. R. Behera1, A. Jhingan2, N. Saneesh2 , Mohit Kumar2, Meenu Thakur1, AbhishekYadav2, Ruchi Mahajan1, Kavita1, Shruti1 and P. Sugathan2

1Department of Physics, Panjab University, Chandigarh 160014, India 2Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067, India

In hot fusion reactions, the maximum cross-sections are obtained at beam energies which are high

enough so that projectile (like 48Ca) and prolate target nuclei can come into contact at minimal distance

(equatorial collisions) and thus form a most compact configuration on the way to the compound

nucleus [1]. The cross-sections decrease rapidly with drop in energy to values where the interaction is

limited to polar collisions and the probability for re-separation of the reaction partners is high.

However, the results are different in the case of projectiles significantly lighter than 48Ca. For example,

in the reaction 16 O + 238U, the experimental data show a large enhancement of evaporation residue (ER)

cross-sections at sub-barrier energies [2], indicating fusion independent of the orientation of the target

nucleus. Hence one may expect a transition from the orientation-independent fusion using light

projectiles to the case of equatorial fusion using 48Ca projectiles. In order to study the anticipated

transition we have studied the reaction 28Si + 232Th with a projectile right in the middle between 16O and48Ca; the chosen target 232Th has similar collective states as 238U. To study the effect of target

orientation, we measured the barrier distribution (BD) for the 28Si+232Th system forming superheavy

element 260Rf104. To extract the BD, the technique of quasi-elastic (QE) scattering at large backward

angles is utilized. The experiment was performed using the 15 UD Pelletron + LINAC accelerator

facility at IUAC, New Delhi. To measure the QE events, the HYTAR facility [3]: an array of hybrid

telescope detectors comprising of ΔE and E detectors is employed. The details about the analysis and

the results will be discussed during the conference.

References

[1] Yu. Ts. Oganessian, J. Phys. G 34, R165 (2007).

[2] K. Nishio et al., Phys. Rev. Lett. 93, 162701 (2004).

[3] Akhil Jhingan et al., Accepted in Nucl. Inst. and Methods in Physics Research A.

0177

Experimental study of neutron rich oxygen isotopes

beyond the drip line

Y. Kondo (Tokyo Institute of Technology) for SAMURAI21 collaboration

Abstract

The sudden change of the neutron dripline from 24O (N=16) to 31F (N=22), called

oxygen anomaly, is one of the exotic phenomena. Recent theoretical studies suggest

importance of three nucleon forces on the binding energies of the oxygen isotopes,

especially for N>16, while available experimental data are limited because the

measurement requires production of extremely neutron rich nuclei.

The region of the oxygen anomaly is also interesting in terms of the shell evolution. It

is well known that the shell closure of the N=20 nuclei disappears in the island of

inversion. Recent in-beam gamma-ray spectroscopy suggests that the N=20 shell gap is

quenched at 29F. The experimental study of 28O is strongly desired to clarify the shell

evolution along the N=20 isotonic chain down to Z=8.

We studied 27O and 28O with SAMURAI spectrometer at RIKEN-RIBF. These unbound

nuclei are produced by two- and one-proton removal reactions on a liquid hydrogen

target from 29Ne and 29F, respectively. Decay products, 24O and neutrons, are detected in

coincidence to reconstruct the invariant mass of the 27O and 28O. The experimental

results will be discussed in the presentation.

0130

Observation of new boron and nitrogen isotopes

Q. Deshayes1, S. Leblond1, F.M. Marques1

for the SAMURAI DayOne collaboration

1LPC Caen, ENSICAEN, Universite de Caen, CNRS/IN2P3, F-14050, Caen, France

The well-established shell structure of the nucleus, that translates into an enhanced stabilityfor systems with a magic number of protons and/or neutrons (2, 8, 20...), is distorted whennuclei approach the landscape limits or driplines, specially the more distant one, the neutrondripline. The most spectacular effect is found at neutron number N =16, in what is known asthe oxygen anomaly: while oxygen can hold at most 16 neutrons, the next element, fluorine, canhold up to 22. In this respect, the neutron-rich tail of the boron and nitrogen isotopic chainsare of particular importance. 21B is the first isotope beyond the dripline at N =16, and 24,25Nrepresent one step further from the known cases 25,26O.

The experiments were performed at the Radioactive Isotope Beam Factory (RIBF) of theRIKEN Nishina Center, as part of an experimental campaign investigating the structure of lightneutron-rich nuclei beyond the dripline (see for example [1, 2]). The most neutron-rich boronand nitrogen isotopes to date, 20,21B and 24,25N, have been observed for the first time usinginvariant-mass spectroscopy following one- or two-proton removal reactions from, respectively,22N, 22C and 26,27F at energies around 230 MeV/nucleon. Their unbound nature lead to thedecay into 19B or 23N plus one or two neutrons.

In this contribution we will describe the results obtained for the mass excess of these isotopes,that are found to be in clear disagreement with the present extrapolated values from massevaluations [3]. The comparison of the resonance energies and widths obtained with predictionsfrom different shell-model calculations will be discussed in terms of the prevalence of the N=16shell gap at Z=5, 7.

[1] Y. Kondo et al., Phys. Rev. Lett. 116, 102503 (2016).

[2] Y. Togano et al., Phys. Lett. B 761, 412 (2016).

[3] M. Wang et al., Chinese Phys. C 36, 1603 (2012).

0144

Mechanism of two-proton emission from the IAS of 22

Mg

Deqing Fang

Shanghai Institute of Applied Physics, Chinese Academy of Sciences

The decay of proton-rich nuclei, especially the two-proton (2p) radioactivity, is an

interesting process that may be observed in nuclei beyond or close to the proton dripline [1].

Two-proton emissions from the excited states of 23

Al and 22

Mg have been measured

experimentally by the nuclear reaction method at RIPS in RIKEN [2,3]. From the spectrum

of relative momentum and open angle between the two protons, we observed strong

component of 2He-like cluster emission from the highly excited states of

22Mg. While for

23Al, sequential proton decay is dominated. In another experiment, the beta-delayed two-

proton emission from 22

Al was investigated through the implantation-decay method at

RIBLL in Lanzhou [4]. The excited states of 22

Mg were populated through the beta-decay

of 22

Al. Two-proton emissions from the IAS of 22

Mg were identified based on the

coincidence of the charged particle and gamma-ray signals. The momentum and emission

angle of the two protons were measured by silicon detector arrays, from which the relative

momentum and opening angle distributions between the two emitted protons could be

obtained. A strong peak in the relative momentum around 20 MeV/c, as well as a peak at

small opening angle between the two emitted protons was observed clearly. It is determined

by fitting the experimental data with the Monte Carlo simulations that the probability of 2He emission from the IAS of

22Mg to the first excited state in

20Ne was around 30%.

Reference:

1. B. Blank and M. Ploszajczak, Rep. Prog. Phys. 71, 046301 (2008).

2. Y. G. Ma, D. Q. Fang et al., Phys.Lett. B 743, 306 (2015).

3. D. Q. Fang et al., Phys. Rev. C 94, 044621 (2016).

4. Y. T. Wang, D. Q. Fang et al., Eur. Phys. J A 54, 107 (2018).

0134

Evidenceforresonancesinthe7αdisassemblyofhighlyexcited28Siand thequestionoftoroidalhigh-spinisomers

X.G.Cao,1,2E.J.Kim,2,3K.Schmidt,2,4K.Hagel,2M.Barbui,2J.Gauthier,2S.Wuenschel,2

G.Giuliani,2,5M.R.D.Rodriguez,2,6S.Kowalski,4H.Zheng,2,5M.Huang,2,7A.Bonasera,2,5

R.Wada,2G.Q.Zhang,1,2C.Y.Wong,8A.Staszczak,9Z.X.Ren,10Y.K.Wang,10S.Q.

Zhang,10J.Meng,10,11andJ.B.Natowitz2

1ShanghaiInstituteofAppliedPhysics,ChineseAcademyofSciences,Shanghai201800,

China;2CyclotronInstitute,TexasA&M University,CollegeStation,Texas77843;3DivisionofScienceEducation,ChonbukNationalUniversity,567Baekje-daeroDeokjin-

gu,Jeonju561-756,Korea;4InstituteofPhysics,SilesiaUniversity,Katowice,Poland;5LaboratoriNazionalidelSud,INFN,viaSantaSofia,62,95123Catania,Italy;6InstitutodeFísica,UniversidadedeSāoPaulo,CaixaPostal66318,CEP05389-970,SāoPaulo,

SP,Brazil;7CollegeofPhysicsandElectronicsInformation,InnerMongoliaUniversityfor

Nationalities,Tongliao,028000,China;8PhysicsDivision,OakRidgeNationalLaboratory,

OakRidge,USA;9InstituteofPhysics,MariaCurie-SklodowskaUniversity,Lublin,

Poland;10StateKeyLaboratoryofNuclearPhysicsandTechnology,SchoolofPhysics,

PekingUniversity,Beijing100871,China;11YukawaInstituteforTheoreticalPhysics,KyotoUniversity,Kyoto606-8502,Japan

Populationof28Sitoveryhighexcitationenergyandit’sde-excitationmeasurementarecarriedoutwithTexasK500superconductingcyclotronbeam onC,SiandTatargetequippedwithNIMROD-ISiS4Piarray.Itisfoundtheαconjugateincidentchanneleffectplaysanimportantroleinfragmentation.Asignificantproportionofeventsconstitutedofnα+Aαisobserved.The7αexitchanneloccupiesanoticeableproportioninthetotalcrosssection.Theexcitationfunctionof7αchannelrevealsresonancestructuresatveryhighexcitationenergy,whichisthefirstobservationofresonancearoundsuchhighexcitationenergyregion.

The7αchanneliscarefullyexploredbytwonuclearstructuremethods:toroidalshellmodel(TSM)andcovariantdensityfunctionaltheory(CDFT),aswellastwohybridtransportmodels:antisymmetrizedmoleculardynamics(AMD)+GEMINImodel,heavy-ion phase-space exploration (HIPSE)+GEMINImodel,where GEMINIisused asafterburnertosimulatethestatisticaldecayfortheprimaryfragment.Thecrosssectionofthepeaksin7αexcitationfunctioncanbewelldescribedbyasemi-empiricalcrosssectionformulacontainingalltoroidalhigh-spinisomer(THSI)statesupto4p-4hexcitations,aswellasthesepeakscentroidsofTHSIobtainedbyTSMandCDFTarewithintheexperimentalerrors.

ThepossibleindicationoftheseresonancepeaksandtheirlinkwithTHSI,whichwassuggested byJ.A.Wheelerin 1950sand quantitativelycalculated byseveralsophisticatedmodelsrecently,arediscussed.

0040

Three-body description of 2n−halo and unbound 2n−systems: 22C and26O

Jagjit Singh1, L. Fortunato3, W. Horiuchi2, and A. Vitturi31Nuclear Reaction Data Centre, Faculty of Science,Hokkaido University, Sapporo 060-0810, Japan

2Department of Physics, Hokkaido University, Sapporo, 060-0810 Japan and3Dipartimento di Fisica e Astronomia “G.Galilei”, and

INFN-Sezione di Padova, via Marzolo 8, I-35131 Padova, Italy

Due to advancements in the radioactive ion beam facility around the various parts of the globe,there has been rapidly increasing interest in the study of the Borromean nuclei sitting right on thetop of neutron driplines and two-neutron decays of unbound systems beyond the neutron dripline.These systems demands a three-body description with proper treatment of continuum, the con-ventional shell-model assumptions being insufficient. Very recently a high precision measurementof interaction cross-section for 22C was made on a carbon target at 235 MeV/nucleon [1] and alsothe unbound nucleus 26O has been investigated, using invariant-mass spectroscopy [2] at RIKENRadioactive Isotope Beam Factory. These high precision measurements and sensitivity of core+npotential with structure of 3- body (core+n + n) system, are the motivation for selecting thesesystems for the present study. We have studied the pairing collectivity in the ground state ofBorromean nuclei 22C and in the 2n- unbound system 26O. For this study we have used our re-cently implemented 3 - body (core+n+n) structure model for ground and continuum states of theBorromean nuclei [3, 4].

We will present the ground state properties of 22C and 26O systems and transitions to thecontinuum that might be of help in disentangling the still poorly known low-energy resonancesand prediciting new resonances of these nuclei. We compare our findings with the more recentexperimental works and the scarce theoretical work that has been done in the recent past on thesesystems.

The neutron single-particle unbound spdf- continuum states of the 21C and 25O system arecalculated in a simple shell model picture for different continuum energy cut-off’s. The sensitivityof the (core+n) potential has been explored for the emergence of different dominant configurationsin the ground state of 22C and 26O. These (core+n) continuum wave functions are used to constructthe two-particle 22C and 26O states by proper angular momentum couplings and taking contributionfrom different configurations. We have explored the role of different pairing interactions such asdensity independent (DI) contact-delta pairing interaction and density dependent (DD) contact-delta pairing interaction in the structure of these systems. Our results shows how the groundstate displays a collective nature, taking contribution from many different oscillating continuumstates that coherently sum up to give an exponentially decaying bound wavefunction in 22C andan oscillating unbound wave function in case of 26O.

[1] Y. Togano et al., Phys. Lett. B761, 412-418 (2016).[2] Y. Kondo et al., Phys. Rev. Lett. 116, 102503 (2016).[3] L.Fortunato, R.Chatterjee, Jagjit Singh and A.Vitturi, Phys. Rev. 90, 064301 (2014).[4] Jagjit Singh, L.Fortunato, A.Vitturi and R.Chatterjee, Eur. Phys. J. A 52 209 (2016).

0111

Matter radius of two-neutron halo nucleus 22C

Y. Togano1 for SAMURAI Dayone collaboration

1 Department of Physics, Rikkyo University, Tokyo 171-8501, Japan

The most neutron-rich carbon isotope 22C has drawn attention due toits possible enhanced halo structure, as suggested by the huge interactioncross section (1.338 ± 0.27 b) on a proton target at 40 MeV/nucleon [1].The estimated root-mean-squared matter radius of 5.4 ± 0.9 fm is muchlarger than known halo nuclei such as 11Li. Due to the large uncertainties inboth of the interaction cross section and the estimated matter radius of theprevious measurement, it has been difficult to draw definite picture of the22C structure through comparison with theoretical predictions. Therefore,more precise data of the 22C matter radius was desired.

With this motivation, the interaction cross sections of the neutron-richcarbon isotopes 22C on a carbon target at 235 MeV/nucleon have been mea-sured by using the SAMURAI spectrometer at RIBF [2]. The root-meansquared matter radius of 22C was deduced by analyzing the obtained in-teraction cross section with a four-body (three-body projectile plus target)Glauber reaction model. The extracted value is about 2σ smaller than theprevious estimate (5.4± 0.9 fm), while it has 7 times smaller uncertainty.

In this contribution we will discuss the extracted root-mean-squared mat-ter radius of 22C along with those measured for 19C and 20C.

[1] K. Tanaka et al., Phys. Rev. Lett. 104, 062701 (2010).[2] Y. Togano et al., Phys. Lett. B 761, 412 (2016).

0186

Low-lying quadrupole and octupole collective excitations in 112,116,118,120,122,124

Sn isotopes

A. Kundu1,2

, S. Santra1,2

, A. Pal1,2

, D. Chattopadhyay1,2

, R. Tripathi2,3

, B. J. Roy1,2

, T.

N. Nag3, B. K. Nayak

1,2, A. Saxena

1,2 and S. Kailas

1

1Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai - 400085, India

2Homi Bhabha National Institute, Anushakti Nagar, Mumbai - 400094, India

3Radiochemistry Division, Bhabha Atomic Research Centre, Mumbai - 400085, India

Inelastic transitions in a nucleus are caused by

electromagnetic (EM) and/or nuclear

interactions with a second nucleus. At large

distances between incoming beam particle and

target, Coulomb scattering to forward angles in

centre-of-mass frame gives reliable structural

information. As smaller distances are

approached, the nuclear amplitude increases

rapidly, causing scattering to backward angles,

making it possible to determine both charge and

mass deformation lengths (δch

and δm) by

measuring the distribution of scattered particles

over a large angular range.

In the present study, differential cross sections

for elastic and inelastic scattering have been

measured for the 7Li +

112,116,118,120,122,124Sn at 28

MeV beam energy, and a simultaneous

description of these channels has been attempted

by means of coupled reaction channels (CRC)

calculations in the (DWBA) limit, with a

consistent set of potential parameters as well as

coupling parameters. The angular distributions

were measured at BARC-TIFR Pelletron

Mumbai, using self-supporting enriched Sn

targets. Six telescopes (ΔE-E) of Si-surface

barrier detectors, placed 10o apart at a distance

of ~21cm from the centre of the scattering

chamber were used to detect the projectile-like

fragments.

The B(E2) or δ2ch

values extracted by

normalizing to the data in the forward region

were found to be consistent with existing

measurements. However, existing B(E3) values

fail to reproduce the data throughout the

angular range. In addition to δch

, a different

multipole parameter (δm) is required to account

for the effect of the nuclear field and is

exclusively extracted by normalizing to the data

beyond the valley of Coulomb-nuclear

interference region. For the λ=2 transition in

each isotope, δ2m is different from δ2

ch by a

maximum of 2-3%. For obtaining the best fit

for λ=3 excitation across the interference

region, it required δ3m << δ3

ch.

The results reflected a strong correlation

between δ2m and δ2

ch, whereas δ3

m was nearly

independent of δ3ch

.

0.0

0.4

0.8

1.2

1.6

c.m (degree)

d/d

(m

b/sr

)

30 60 90 120 15030 60 90 120 150

0.0

0.4

0.8

1.2

Ex = 2.33

MeV

Ex = 2.40

MeV

Ex = 2.49

MeV

Ex = 2.61

MeV

3

m =

0.570 fm

3

m =

0.556 fm

3

m =

0.477 fm

3

m =

0.459 fm

(c) 118

Sn (d) 120Sn

(e)122

Sn (f) 124

Sn

0.0

0.4

0.8

1.2

1.6 Ex = 2.35

MeV

Ex = 2.27

MeV

3

m =

0.548 fm

(a) 112

Sn (b) 116

Sn

(c) 118

Sn (d) 120

Sn

c.m (degree)

3

m =

0.581 fm

28 MeV data

3

ch (p,p')

3

ch (e,e')

3

ch (CoulEx)

DFM calc.

Fig. 1: Present work showing the expt. cross

sections and CRC calculations (solid, dashed

and dash-dot lines for Woods-Saxon potential

& dash-dot-dot lines for Double Folding Model

potential) for λ=3 inelastic scattering.

0099

Blurring boundary between the seniority regime and collective motion

Chong Qi

KTH Royal Institute of Technology, SE-10691 Stockholm

The E2 transition strengths, B(E2) values, give particularly precise information

on the competition between the collective and single-particle degree of freedom.

An important observable to study the development of collectivity is the B(E2; 4+ → 2 + /B E2; 2+ → 0 + ratio B4/2 . The B4/2 ratio is usually greater than unity.

These values are 1.4 and 2.0 for an ideal rotor and a vibrator, respectively.

Whereas the seniority scheme usually leads to different behaviors.

In this contribution I will show examples that contrast with our standard

understanding. The yrast spectra of Te isotopes show a vibrational-like equally-

spaced pattern but the few known E2 transitions show anomalous rotational-like

behavior, which cannot be reproduced by collective models. Large-scale shell

model calculations reproduce well the equally-spaced spectra of those isotopes

as well as the constant behavior of the B(E2) values in 114Te[1]. For nuclei

involving protons or neutrons in j=9/2 orbitals, the partial conservation of

seniority can lead to dramatic changes to the E2 decay pattern that have never

been seen before [2]. The B4/2 ratios in quantum phase transitional nuclei

around N=90 also show a similar exotic behavior [3].

[1]C Qi, Physical Review C 94 (3), 034310 (2016)

[2]C Qi, Physics Letters B 773, 616-619 (2017)

[3]B. Cederwall et al, Phys. Rev. Lett, in press

0075

VALENCE PARTICLE/HOLE-CORE COUPLINGS IN NEUTRON-RICH, EXOTIC NUCLEI

S. Bottoni1,2, S. Leoni1,2, B. Fornal3, G. Colò1,2, P. F. Bortignon1,2, G. Benzoni2, A. Bracco1,2, N. Cieplicka-Oryńczak3, F. C. L. Crespi1,2, M. Jentschel4, U. Köster4, Ł. Iskra3, C. Michelagnoli4,

B. Million2, P. Mutti4, Y. Niu5 T. Soldner4, C. A. Ur5, W. Urban6

and the EXILL-FATIMA collaboration

1Dipartimento di Fisica, Università degli Studi di Milano, Milano, Italy2INFN Sezione di Milano, Milano, Italy

3Institute of Nuclear Physics, Kraków, Poland4Institut Laue-Langevin, Grenoble, France5ELI-NP, Magurele-Bucharest, Romania

6Faculty of Physics, University of Warsaw, Warsaw, Poland

In the atomic nucleus, couplings between single-particles/holes and collective (phonons) and non-collective excitations are of primary importance, as they are responsible for many phenomena, from the damping of giant resonances, to the quenching of spectroscopic factors and the anharmonicity of vibrational spectra. In general, the coexistence between fermionic and bosonic degrees of freedom is a well-known process which occurs, for instance, in condensed matter, where electrons and plasmons are the counterpart or protons/neutrons and phonons. Consequently, the study of such properties in atomic nuclei will have a broader impact on different fields of physics, in terms of a comprehensive description of interacting many-body quantum systems. While in the past particle-vibration coupling has been studied in a limited number of nuclei, it is still under discussion whether neutron rich systems display similar characteristics and how couplings with core excitations are influenced by the proton-to-neutron ratio and shell evolution. To explore this aspect, we present recent experimental results in the medium-heavy mass regions around the doubly-magic, neutron-rich 48Ca and 132Sn isotopes. In particular, we discuss new spectroscopic information on the 47Ca, 49Ca, 133Sb and 131Sn isotopes, obtained in different experimental campaigns, at ILL (Grenoble) [1-2] and LNL (Italy) [3], by using large state-of-the-art g-ray setups based on high-resolution, high-efficiency HpGe Detectors. Experimental results are interpreted by a new microscopic theoretical model, the Hybrid Configuration Mixing Model [4,5], specifically designed by the Milano group to describe the structure of nuclear systems with one valence particle/hole outside a doubly-closed core. The model includes couplings between valence nucleons and core excitations, by means of Hartree-Fock (HF) and Random Phase Approximation (RPA) calculations, using the Skyrme effective interaction, and accounts for both phonons and non-collective p-h configurations. This cutting-edge, beyond-mean-field approach is aimed at providing a consistent interpretation of hybridization phenomena, as due to the residual interaction of the nuclear Hamiltonian. The agreement between experimental and theoretical energies, electromagnetic transition probabilities and spectroscopic factors will be outlined, showing the relevance of the new approach, as compared to traditional shell model calculations with a frozen core. Recent improvements of the model and possible future experimental developments with radioactive beams will be also discussed.

[1] G. Bocchi et al., Phys. Lett. B 760, 273 (2016). [2] S. Bottoni et al., in preparation. [3] D. Montanari et al., Phys. Lett. B 697, 288 (2011). [4] G. Colò et al., Phys. Rev. C 95, 034303 (2017). [5] S. Bottoni et al., in preparation.

0095

- spectroscopy of 195Os at KISS

M. Ahmed A, B, Y.X. Watanabe B, Y. Hirayama B, M. Mukai A, B, C, J.H. Park D,

P. Schury B, Y. Kakiguchi B, S. Kimura B, C, A. Ozawa A, M. Oyaizu B, M. Wada B, C and

H. Miyatake B

A University of Tsukuba, Tsukuba, Ibaraki 305-0006, Japan.

B Wako Nuclear Science Center, Institute of Particle and Nuclear Studies, High Energy

Accelerator Research Organization (KEK), Wako, Saitama 351-0198, Japan.

C Nishina Center for Accelerator-Based Science, RIKEN, Wako, Saitama 351-0198,

Japan.

D Institute for Basic Science, Daejeon, 151-742, Korea.

Abstract:

Nuclei in the vicinity of the doubly magic nucleus 208Pb (Z = 82, N = 126) show various

aspects of nuclear structure due to a complex interplay between the single-particle and

collective degrees of freedom, such as long-lived isomers, shape transitions and competition

between allowed Gamow-Teller and first-forbidden -decay transitions. This competition

makes it difficult to predict the nuclear properties like lifetimes and masses without

experimental information. KEK isotope separation system (KISS) [1] has been developed to

study them for the neutron-rich nuclei around N =126 [2].

The neutron-rich radioactive isotope of 195Os was produced in its ground and isomeric

states by the multi-nucleon transfer reaction of 136Xe + 198Pt at KISS for - spectroscopy. The

-rays and -rays were detected by the Multi-Segmented Proportional Gas Counter (MSPGC)

[3] and Super Clover High-Purity Germanium detectors, respectively. The -decay half-life of 195Os ground state was evaluated to be 6.5(4) minutes which was consistent with literature

value (6.5(11) min.) [4]. Twenty-four -rays were observed in coincidence with the MSPGC.

The energies of eighteen -rays were consistent with the literature values of Ref. [5] and six -

rays (111, 149, 169, 279, 305 and 776 keV) were newly found. The -rays of 305 and 776 keV

were identified as -delayed ones. Four -rays of 111, 149, 169 and 279 keV were associated

with a long-lived isomeric state with shorter half-life of 47(6) s. Cascade transitions among

those -rays and Osmium K X-rays were found in all gated spectra, indicating that these

transitions belong to internal decay from a new isomeric state of 195Os. The absolute -

transition strength from the ground state of 195Os to the excited states and ground state of 195Ir

have been deduced. A possible level scheme from newly observed isomeric transitions and the

-delayed -ray spectroscopy of the ground state will be discussed.

References

[1] Y. Hirayama et al., Nucl. Instr. Meth. B 412, 11 (2017).

[2] Y.X. Watanabe et al., Phys. Rev. Lett. 115, 172503 (2015).

[3] M. Mukai et al., Nucl. Instr. Meth. A 884, 1 (2018).

[4] M. Birch et al., Phys. Rev. C 88, 067301 (2013).

[5] G. G. Colvin et al., Nucl. Phys. A 465, 240 (1987).

0101

Reaction Mechanisms of Exotic Nuclear Systems at Low Energies

Chengjian Lin China Institute of Atomic Energy, P.O. Box 275(10), Beijing 102413

With the development of radioactive ion beams (RIBs) and detection systems, reaction mechanisms of exotic nuclear systems at low energies become a hot topic of current interest in nuclear physics. In the talk, I would like to present some new results obtained by the nuclear reaction group of the CIAE, mainly including the following two topics.

1) Optical model potentials (OMPs) of exotic nuclear systems. Due to thelimitations of intensity and quality of RIBs, it is rather difficult to extract the OMPs of exotic nuclear systems by the elastic scattering. For this reason, a transfer reaction method was proposed and applied to extract the OMPs of 6He+12C, 64Zn, 209Bi systems via 11B, 63Cu, 208Pb(7Li,6He) reactions [1]. The complete picture of threshold anomaly behavior has been obtained in the 6He+209Bi system for the first time [2]. Results show that the dispersion relation is not applicable for the exotic nuclear systems. Possible reasons are discussed but further study is strongly required to discover the underlying physics.

2) Reaction mechanism of weakly-bound nuclear systems. An important task isto understand the breakup effects as well as its mechanism. To this end, a complete-kinematics measurement method was developed and applied in the 17F+58Ni, 89Y [3], 208Pb and 7Be+208Pb experiments. The processes of elastic scattering, breakup/transfer, and fusion evaporation have been identified successfully. Preliminary results of 17F+58Ni show that the fusion is suppressed at above-barrier energies due to the loss of incident flux while enhanced below-barrier due to couplings to the continuum states. Detailed theoretical analyses are still in progress.

[1] L. Yang, C. J. Lin, H. M. Jia et al., Phys. Rev. C 96, 044615 (2017); Phys. Rev. C 95, 034616 (2017); Phys. Rev. C 89, 044615 (2014); Phys. Rev. C 87, 047601 (2013).

[2] L. Yang, C. J. Lin, H. M. Jia et al, Phys. Rev. Lett. 119, 042503 (2017). [3] G. L. Zhang, G. X. Zhang, C. J. Lin et al., Phys. Rev. C 97, 044618 (2018).

0024

Swati Modi, M. Patial, and P. Arumugam

Department of Physics, Indian Institute of Technology, Roorkee 247667, India

We study the structural properties of triaxially deformed nuclei with themicroscopic non-adiabatic quasiparticle approach [1], where the core energiesare coupled with the quasiparticle states to obtain the matrix elements of theparticle-core system [2, 3]. This approach for calculating the wave functionsof the odd-A nuclei is numerically intensive and reduces to the conventionalparticle-rotor model under the assumption of a constant moment of inertia[4]. The configuration of 129Xe has investigated in this work and revealedthat the triaxial shape is important for this nucleus. The deformation pa-rameters β2 ∼ 0.15 and γ ∼ 25◦ obtained from our approach correspond tothe best agreement with the data [5]. In Ref. [5], two signature componentsare identified making two band structures based on 3/2+ and 5/2+ states,respectively, whereas 1/2+ is the ground state of 129Xe. We are able to un-ambiguously assign the configurations of 1/2+, 3/2+, and 5/2+ states witha major contribution of 46% from νd3/2. Contribution from s1/2, g7/2, d5/2are 23%, 18% and 12%, respectively. The remaining contribution is fromg9/2 and other higher orbitals. Since

129Xe is triaxial, there is a configura-tion mixing from different orbitals around Fermi level. All the three states1/2+, 3/2+, and 5/2+ are exhibiting similar configuration, thus we infer thatall these states are forming a band based on 1/2+. From the configurationcalculation, it can be unequivocally identified that the two signature partnerbands are based on 1/2+ and 3/2+ states.

[1] P. Arumugam, L. S. Ferreira, and E. Maglione, Phys. Rev. C 78, 041305(R)(2008); Phys. Lett. B 680, 443 (2009).

[2] Swati Modi, M. Patial, P. Arumugam, E. Maglione, and L.S. Ferreira, Phys.Rev. C 95, 024326 (2017); 95, 054323 (2017).

[3] Swati Modi, M. Patial, P. Arumugam, L.S. Ferreira and E. Maglione, Phys.Rev. C 96, 064308 (2017).

[4] K. T. Hecht and G. R. Satchler, Nucl. Phys. 32, 286 (1962).

[5] Y. Huang et al., Phys. Rev. C 93, 064315 (2016); Z. Zhao et al., Z. Phys. A331, 113 (1988).

1

0044

Nonadiabatic quasiparticle approach to study configurationmixing in triaxially deformed 129Xe

Studies on nuclear astrophysics and nuclear clustering with low-energyRI beams at CRIB

H.Yamaguchi1, S. Hayakawa1, L. Yang1,2, H. Shimizu1, D. Kahl3 and CRIB collaboration

Abstract— Studies on nuclear astrophysics, nuclear structure,and other interests have been performed using the radioactive-isotope (RI) beams at the low-energy RI beam separator CRIB,operated by Center for Nuclear Study (CNS), the University ofTokyo. Recent improvements on the beam development at CRIBand experimental studies are discussed.

The elastic resonant scattering is a striking tool to studyastophysical reactions and nuclear clusters. In particular, whenit is coupled with a thick target and inverse kinematics, themeasurement can be very efficient and even feasible with RIbeams. Recent successful applications of the α resonant elasticscattering with the thick-target method at CRIB are for the7Be+α [1], 10Be+α [2], 30S+α [3], and 15O+α systems.

By measuring the resonance parameters, we can evaluatethe resonant reaction rates of astrophysically relevant reac-tions. With our 7Be+α and 30S+α measurements, 7Be(α,γ)and 30S(α,p) reactions in explosive stellar environments werestudied. The α-particle clustering in the compound nucleiis another interesting topic which can be studied with theresonant elastic scattering. In the 10Be+α [2] measurement,three resonances which perfectly correspond to the prediction ofa linear-chain structure by Suhara-En’yo [4], [5] were observed,giving a strong evidence of the existence of such an exoticstructure.

In 2017, an 26Al beam as a mixture of the ground (5+) andisomeric (0+) states was produced at CRIB, and applied for aproton resonant scattering measurement. The measurement isrelevant for the identification of the astrophysical sites of thegalactic γ-ray.

There have also been measurements based on the indirecttechnique of the reaction measurement. The first Trojan horsemethod (THM) measurement using an RI beam was performedat CRIB, to study the 18F(p, α)15O reaction at astrophysicalenergies via the three body reaction 2H(18F, α15O)n. The 18F(p,α)15O reaction rate is crucial to understand the 511-keV γ-rayproduction in nova explosion phenomena, and we successfullyevaluated the reaction cross section at novae temperature andbelow experimentally for the first time [6]. The second THMexperiment at CRIB was performed for the cosmological 7Liabundance problem. The 7Be(n, p) and (n, α) are possibledestruction reactions to explain the discrepancy in 7Li betweenthe Big-bang nucleosynthesis model and the observed 7Liabundance. We performed a THM measurement with 7Be beamat CRIB as one of the first applications of THM for neutroninduced reactions [7].

REFERENCES

[1] H. Yamaguchi, D. Kahl, Y. Wakabayashi, S. Kubono, T. Hashimoto,S. Hayakawa, T. Kawabata, N. Iwasa, T. Teranishi, Y. Kwon, D. N.Binh, L. Khiem, and N. Duy, “Alpha-resonance structure in 11C studied

1 Center for Nuclear Study (CNS), University of Tokyo, 2-1 Hirosawa,Wako, Saitama 351-0198, Japan

2 China Institute of Atomic Energy, P.O. Box 275(10), Beijing 102413,China.

3 School of Physics and Astronomy, the University of Edinburgh, PeterGuthrie Tait Road, Edinburgh EH9 3BF, UK.

via resonant scattering of 7Be+α and 7Be(α, p) reaction,” Phys. Rev.C, vol. 87, p. 034303, Mar 2013.

[2] H. Yamaguchi, D. Kahl, S. Hayakawa, Y. Sakaguchi, K. Abe, T. Nakao,T. Suhara, N. Iwasa, A. Kim, D. Kim, S. Cha, M. Kwag, J. Lee,E. Lee, K. Chae, Y. Wakabayashi, N. Imai, N. Kitamura, P. Lee,J. Moon, K. Lee, C. Akers, H. Jung, N. Duy, L. Khiem, and C. Lee,“Experimental investigation of a linear-chain structure in the nucleus14C,” Phys. Lett. B, vol. 766, pp. 11–16, 2017. [Online]. Available:http://www.sciencedirect.com/science/article/pii/S0370269316307961

[3] D. Kahl, H. Yamaguchi, S. Kubono, A. A. Chen, A. Parikh,D. N. Binh, J. Chen, S. Cherubini, N. N. Duy, T. Hashimoto,S. Hayakawa, N. Iwasa, H. S. Jung, S. Kato, Y. K. Kwon,S. Nishimura, S. Ota, K. Setoodehnia, T. Teranishi, H. Tokieda,T. Yamada, C. C. Yun, and L. Y. Zhang, “First measurement of30S + α resonant elastic scattering for the 30S(α, p) reaction rate,”Phys. Rev. C, vol. 97, p. 015802, Jan 2018. [Online]. Available:https://link.aps.org/doi/10.1103/PhysRevC.97.015802

[4] T. Suhara and Y. Kanada-En’yo, “Quadrupole deformation β and γconstraint in a framework of antisymmetrized molecular dynamics,”Progress of Theoretical Physics, vol. 123, no. 2, pp. 303–325, 2010.

[5] T. Suhara and Y. K. En’yo, “Be-α correlations in the linear-chainstructure of C isotopes,” Phys. Rev. C, vol. 84, p. 024328, Aug 2011.

[6] S. Cherubini, M. Gulino, C. Spitaleri, G. G. Rapisarda,M. La Cognata, L. Lamia, R. G. Pizzone, S. Romano, S. Kubono,H. Yamaguchi, S. Hayakawa, Y. Wakabayashi, N. Iwasa, S. Kato,T. Komatsubara, T. Teranishi, A. Coc, N. de Sereville, F. Hammache,G. Kiss, S. Bishop, and D. N. Binh, “First application ofthe trojan horse method with a radioactive ion beam: Studyof the 18F(p, α)15O reaction at astrophysical energies,” Phys.Rev. C, vol. 92, p. 015805, Jul 2015. [Online]. Available:http://link.aps.org/doi/10.1103/PhysRevC.92.015805

[7] Hayakawa, S., “Trials for the cosmological 7Li problem with 7Bebeams at crib and collaborating studies,” Il Nuovo Cimento, vol. 39C,p. 370, 2016.

0053

N. Rijal, I. Wiedenhoever, L.T. Baby, P. Hoeflich (Florida State University, Department of Physics, Tallahassee, FL 32306, USA)J. Blackmon (Louisiana State University, Department of Physics & Astronomy, Baton Rouge, LA 70803, USA)

The cross sections of nuclear reaction 7Be+d, which is a possible path of destruction of mass-7 nuclides in Big-Bang nucleosynthesis, were measured at center-of-mass energies between 0.2 MeV and 1.5 MeV. The experiment was performed with the ANASEN active-target detector system at the RESOLUT facility of Florida State University. We measured cross sections consistent with prior measurements at higher energies but significantly higher at lower energy, especially in the Gamow window. The implications of these cross-sections in the primordial lithium abundance will be discussed.

0033

The 7Be(n,α)4He reaction studied via THM for the cosmo-logical Li-problem

L. Lamiaa,b, C. Spitaleria,b, C.A. Bertulanic, S. Hayakawah, S.Q. Houc,d, M. La Cognatab, M.Mazzoccof,g, R.G. Pizzoneb, D. Pierroutsakoui, S. Romanoa,b, M.L. Sergib, A. Tuminob,e

aDipartimento di Fisica e Astronomia-Universita’ di Catania (Catania, Italy),bLaboratori Nazionali del Sud, INFN-LNS (Catania, Italy),c Department of Physics and Astronomy, Texas A&M University-Commerce (TX),dInstitute of modern Physics, Chinese Academy of Science (Lanzhou, China),eFacolta’ di Ingegneria e Architettura, Universit degli Studi di Enna “Kore” (Enna, Italy),f Dipartimento di Fisica, Universit di Padova, Padova (Italy),gINFN-LNL, Legnaro (Italy),hCNS, University of Tokyo (Japan),iINFN-Sezione NapoliLithium puzzle is one the most intriguing unsolved problem at our days. Its predictedabundance by CMB evaluations is generally accepted to be a factor ∼3 higher than theone deduced by halo stars (see [2] for a general review). However, recent observationsin Pop.II objects tend to predict an higher value of primordial lithium [1] thus possiblyalleviating the Li-problem. In this charming scenario, reaction rate determination forboth the producing and the destruction channels involving lithium are really necessaryin order to reduce the corresponding uncertainties. In particular, the role of the unsta-ble 7Be during the early epoch of the Big Bang Nucleosynthesis is currently matter ofstudy in view of the long-standing 7Li cosmological problem [2]. Recently, the TrojanHorse Method (THM) [3] have been applied for measuring the cross section of the (n,α)reaction channel on 7Be by means of charge-symmetry hypothesis applied to the pre-vious 7Li(p,α)4He THM data corrected for Coulomb effects. The deduced 7Be(n,α)4Hedata overlap with the Big Bang nucleosynthesis energies and the deduced reactionrate allows us to evaluate the corresponding cosmological implications [4]. In addition,a devoted THM experiment has been also performed at INFN-LNL by using deuteron asTHM nucleus in the 7Be+2H quasi-free reaction ignited at a beam energy of 22 MeV. Thepreliminary results will be shown in connection with the further experiment performedat CRIB [5]

References[1] Nordlander T. et al., The Astrophys. Journ 753, 48 (2012)[2] C. Bertulani & T. Kajino, Progress in Particle and Nuclear Physics 89, 56 (2016)[3] R.E. Tribble et al., Report on Progress Physics 77, 106901 (2014)[4] L. Lamia et al., The Astrophysical Journal 850, 175 (2017)[5] S. Hayakawa et al., AIP 1947, 020011 (2018)

1

0127

The SE1 factor of radiative α capture on 12C ineffective field theory

Shung-Ichi Ando1,

School of Mechanical and ICT convergence engineering, SunmoonUniversity, Asan, Chungnam 31460, Republic of Korea

The SE1-factor of radiative α-capture on 12C is studied in effective field theory up to

next-to-leading order. We discuss a modification of the counting rules for the radiative

capture amplitudes and find two unfixed parameters remained in the amplitudes. Those

two parameters are fitted to the experimental SE1 data, and an SE1 factor is calculated

at the Gamow-peak energy as SE1 = 86 ± 4 keV·b. We find that our result is in good

agreement with the other estimates reported recently. We also discuss the uncertainty of

the estimate of the present approach.

1mailto:sando@sunmoon.ac.kr

1

0037

Insights on the carbon burning at astrophysicalenergies by fast-timing gamma-particle coincident

measurements

Sandrine Courtina for the STELLA collaboration

a IPHC and University of Strasbourg, France

Fusion reactions play an essential role in understanding the energy production, thenucleosynthesis of chemical elements and the evolution of massive stars. Thus, the directmeasurement of key fusion reactions at thermonuclear energies is of very high interest. Thecarbon burning in stars is essentially driven by the 12C+12C fusion reaction. This reactionis known to show prominent resonances at energies ranging from a few MeV/nucleon downto the sub-Coulomb regime, possibly due to molecular 12C-12C configurations in 24Mg [1].The persistence of such resonances down to the Gamow energy window is an interestingquestion. This reaction could also be subject to the fusion hindrance phenomenon which hasbeen evidenced for medium mass nuclei and measured in numerous systems [2].

This contribution will discuss recent measurements performed in the 12C+12C systemat deep sub-barrier energies using the newly developed STELLA apparatus associated withthe UK FATIMA detectors for the exploration of fusion cross-sections of astrophysicalinterest [3]. Gamma-rays have been detected in an array of LaBr3 detectors and protonsand alpha particles were identified in double-sided silicon-strip detectors. A novel rotatingtarget system has been developed able to sustain high intensity carbon beams deliveredby the Andromede faciity of the University Paris-Saclay and IPN-Orsay (France). Theγ-particle coincidence technique as well as nanosecond timing conditions have been usedin the analysis in order to minimize background. This has allowed to obtain astrophysical Sfactors down to the Gamow window which will be presented and discussed in the frame ofprevious measurements. 1

[1] D. Jenkins and S. Courtin J. Phys. G: Nucl. Part. Phys. 42 034010 (2015).[2] C.L. Jiang et al., Phys.Rev. Lett. 89 052701(2002).[3] M. Heine et al., Nucl. Inst. Methods A (2018), under press,https://www.sciencedirect.com/science/article/pii/S0168900218307678

1This work was supported by the French ’Investissements d’Avenir ’program, the University of Strasbourg ’IdExAttractivity’ program and the USIAS, Strasbourg, France.

0137

Characterizing the astrophysical S-factor for 12C + 12Cwithwave-packet dynamics

Alexis Diaz-Torresa and Michael Wiescherb

aDepartment of Physics, University of Surrey, Guildford GU2 7XH, UKbJINA and University of Notre Dame, Indiana 46656, USA

A quantitative study of the astrophysically important sub-barrier fusion of 12C + 12C willbe presented [1]. Low-energy collisions are described in the body-fixed reference frameusing wave-packet dynamics within a nuclear molecular picture. A collective Hamilto-nian drives the time propagation of the wave-packet through the collective potential-energy landscape. The fusion imaginary potential for specific dinuclear configurationsis crucial for understanding the appearance of resonances in the fusion cross section.In contrast to other commonly used methods, such as the potential model and theconventional coupled-channels approach, these new calculations reveal three resonantstructures in the S-factor, as shown in Fig. 1. The structures correlate with similar struc-tures in the data. The structures in the data that are not explained are possibly due tocluster effects in the nuclear molecule, which need to be included in the new approach.

1015

1016

1017

1018

2 3 4 5 6

S-f

acto

r (M

eV

b)

Ec.m. (MeV)

Jiang et al.

Spillane et al.

Aguilera et al.

Becker et al.

High and Cujec

Mazarakis and Stephens

Patterson et al.

1015

1016

1017

1018

2 3 4 5 6

S-f

acto

r (M

eV

b)

Ec.m. (MeV)

NORM=1.0

NORM=0.98

curv. pot. pockets

Figure 1: The astrophysical S-factor excitation function for 12C + 12C. Measurements(symbols) are compared to model calculations (lines), indicating that molecular struc-ture and fusion are interconnected. The model calculations are shown for (i) two globalfactors that multiply the collective potential-energy landscape (thin solid and dashedlines), and (ii) a reduction by 15% of the curvature of the potential pockets (thick solidline). The latter greatly improves the location of the predicted resonant structures.

References[1] A. Diaz-Torres and M. Wiescher, Physical Review C 97 (2018) 055802-1-8.

13th International Conference on Nucleus-Nucleus Collisions

0032

At the future heavy-ion project at J-PARC (J-PARC-HI), we will study extremely dense

matter 7 times as high as the normal nuclear density that was created in heavy-ion

collisions at 1-19 AGeV/c. We will search for phase structures such as the first-order

phase boundary and the critical point in the QCD phase diagram. We also aim at

studying the properties of dense matter, such as the equation of state (EOS), leading to

studies of neutron stars and neutron star mergers.

In this talk, we will show the heavy-ion acceleration scheme at J-PARC, where we

expect to produce the world's highest-rate heavy-ion beams of 1011 with the ion species

up to U. We will measure various observables in extremely high statistics, such as

event-by-event fluctuations, dileptons, and multi-strangeness systems. We will show the

design of the spectrometers to measure hadrons, dileptons, and hypernuclei, and

evaluate their key performance.

0255

Tale of coherent photon products: from UPC to HHIC

Wangmei Zha11Department of modern physics, University of Science and Technology of China

The coherent photon-nucleus and photon-photon interactions has been studied in detail to probethe gluon distribution in nucleus and to test QED via relativistic heavy-ion collisions. These kindof interactions are traditionally thought to be only exist in ultra-peripheral collisions (UPC), wherethere is no hadronic interactions. Recently, significant excess of J/ψ yield and dielectron pairproduction at very low transverse momentum (pT < 0.3 GeV/c) were observed by the ALICE andSTAR collaborations in peripheral A+A collisions, which points to evidence of coherent photonproducts in hadronic heavy-ion collisions (HHIC). The possible survival of photoproduced J/ψ andelectron pair merits theoretical investigations, which are currently rare on the market.

In this talk, we report on calculations of J/ψ yield from coherent photon-nucleus interactions anddilepton production from photon-photon interactions in HHIC at RHIC and LHC energies. Themodel used to calculate the cross section is discussed and the expected yield are compared withexperimental results from RHIC and LHC. We predict the coherent production contribution of J/ψand dielectron from isobaric collisions (Ru+Ru, Zr+Zr) for the further experimental test at RHIC.

This talk is based on: 1) Wangmei Zha etal., Phys. Lett. B781 (2018) 182; 2) Wangmei Zha etal.,Phys. Rev. C97 (2018) 044910; 3) paper in preparation.

0058

Collision energy and centrality dependence oflight nuclei (triton) production at STAR

Dingwei Zhang for the STAR Collaboration

Central China Normal University

In high-energy nuclear collisions, light nuclei provide a unique tool to explore1

the QCD phase structure. The production of light nuclei is sensitive to the2

temperature and phase-space density of the system at freeze-out. In addi-3

tion, phase transition will lead to large baryon density fluctuations, which4

will be reflected in the light nuclei production. For example, the ratio of5

proton (N(p)) and triton (N(t)) to deuteron (N(d)) yields, which is defined6

as N(t)·N(p)/N2(d), may be used as a sensitive observable to search for the7

QCD critical point [1].8

In this talk, we will report the first results of the collision energy and cen-9

trality dependence of triton production in Au+Au collisions at√sNN = 7.7,10

11.5, 14.5, 19.6, 27, 39, 62.4, and 200 GeV measured by the STAR experiment11

at RHIC. We will present the beam energy dependence for the coalescence12

parameter B3(t) and the yield ratio of N(t)·N(p)/N2(d). Their physics im-13

plications will be discussed.14

[1] K. J. Sun, L. W. Chen, C. M. Ko and Z. B. Xu, Phys. Lett. B774, 103(2017).

1

0084

Extracting High-Density QCD properties from Heavy Ion-Collisionsat J-PARC energy regions

V. Bornyakov 1,2, D. Boyda 1, V. A. Goy 1, H. Iida 1, A. Molochkov 1, A. Nakamura 1,3,4,M. Wakayama 1,4 and V. Zakharov 1,2 1,2,3

In Refs.[1] and [2], the temperature T and the chemicalpotential µ are extracted for created systems in high energyheavy ion collisions for several insident energies. See Fig.1

40

60

80

100

120

140

160

0 100 200 300 400 500 600 700 800

T (

MeV

)

μB (MeV)

This work

Cleymans et al., PRC (2006)

J-PARC?

Fig. 1. Figure taken from [2], in which we add a estimated T −µ region.

In Ref.[3], we pointed out that a canonical approach isa powerful tool to analyse the heavy ion collisions: In thisformula, the grand partition function, Z(µ, T ) is expandedin terms of the canonical partition functions, zn(T ) as

Z =∑

n

znξn. (1)

The canonical partition functions, zn can be obtained fromthe experimental data and by the lattice numerical simula-tions.

0

2

4

6

8

10

12

14

0 50 100 150 200

This methodCleymans 2006Alba 2014

√

sNN GeV

ξ

Fig. 2. Figure taken from [3]. Here ξ = exp(µ/T ).

1School of Biomedicine, Far Eastern Federal University, Vladivostok690950, Russia

2 ITEP, Russia3 Nishina Center, RIKEN, Wako 351-0198, Japan4 RCNP, Osaka University, Osaka, 567-0047, Japan

Fig.2 tells us that this approach is consistent with theprevious analyses, and that indeed J-PARC energy regionsµ/T increases rapidly. Once we obtain zn, we can calculatehigher moments such as Kurtosis.

0 2 4 6 8

10 12 14 16 18

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5

λ 2/λ

1

µB/T

s11.5s19.6

s27

s39s62.4s200

T1.35TcT0.93Tc

0.3 0.6 0.9 1.2 1.5

0.6 0.8 1 1.2 1.4 1.6 1.8

Fig. 3. Figure taken from [4], where we show λ2/λ1 for experimentaldata at several energies and two lattice results above and below the phasetransition.

REFERENCES

[1] J. Cleymans, H. Oeschler, K. Redlich and S. Wheaton, PhysicalReview C73, (2006) 034905,

[2] P. Alba et al., Phys. Lett. B738, (2014), 305.[3] A. Nakamura and K. Nagata, Prog. Theor. Exp. Phys. 2016, 033D01,

arXiv:1305.0760v2 [hep-ph][4] D. Boyda et al., arXiv:1704.03980v3

0140

Title: Combined Constraints on the Equation of State of Dense Neutron-rich Matter from Terrestrial Nuclear Experiments and Observations of Neutron Stars

Author: Naibo Zhang1,2, Bao-An Li1, Jun Xu3

Affiliation: 1. Department of Physics and Astronomy, Texas A&M University-Commerce,Commerce, TX 75429, USA; Bao-An.Li@Tamuc.edu 2. Shandong Provincial Key Laboratory of Optical Astronomy and Solar-TerrestrialEnvironment, Institute of Space Sciences, Shandong University, Weihai, 264209, Peopleʼs Republic of China 3. Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai201800, Peopleʼs Republic of China

Abstract: Within the parameter space of the equation of state (EOS) of dense neutron-rich matter limited by existing constraints mainly from terrestrial nuclear experiments, we investigate how the neutron star maximum mass Mmax>2.01±0.04Msun, radius 10.62 km<R1.4<12.83 km and tidal deformability Λ1.4<800 of canonical neutron stars together constrain the EOS of dense neutron-rich nucleonic matter. While the 3D parameter space of Ksym (curvature of nuclear symmetry energy), Jsym, and J0 (skewness of the symmetry energy and EOS of symmetric nuclear matter, respectively) is narrowed down significantly by the observational constraints, more data are needed to pin down the individual values of Ksym, Jsym, and J0. The J0 largely controls the maximum mass of neutron stars. While the EOS with J0=0 is sufficiently stiff to support neutron stars as massive as 2.37Msun, supporting the hypothetical ones as massive as 2.74Msun (composite mass of GW170817) requires J0 to be larger than its currently known maximum value of about 400 MeV and beyond the causality limit. The upper limit on the tidal deformability of Λ1.4=800 from the recent observation of GW170817 is found to provide upper limits on some EOS parameters consistent with but far less restrictive than the existing constraints of other observables studied.

0047

Hyperons in dense matter: what do the constraints tell us for equationof state?

Constanca Providencia 1

The recently accurate measurement of the mass of twopulsars close to or above 2 M� has raised the questionwhether such large pulsar masses allow for the existenceof exotic degrees of freedom, such as hyperons, insideneutron stars. For core-collapse and neutron star mergersimulations it is important to have at hand adequate equationsof state, describing the underlying dense and hot matter asrealistically as possible, and, in particular, one may ask whatis the role of hyperon degrees of freedom.

We first demonstrate the importance of a unified micro-scopic description for the different baryonic densities ofthe star [1]. We will discuss how the existing hypernucleiproperties may constrain the neutron star equation of stateand confront the neutron star maximum masses obtainedwith equations of state calibrated to hypernuclei propertieswith the astrophysical 2 M� constraint [2]. The study isperformed using a relativistic mean field approach to describeboth the hypernuclei and the neutron star equations of state.Unified equations of state a re obtained. Some of thesemodels also satisfy other well established laboratory ortheoretical constraints.

We will show that the currently available hypernucleiexperimental data and the lack of constraints on the asym-metric equation of state of nuclear matter at high densitiesdo not allow to further constrain the neutron star matterequation of state using the recent 2 M� observations. Wewill discuss how tidal deformability may put tight boundson several EoS parameters, in particular, on the slope of theincompressibility and the curvature of the symmetry energy[3].

We next discuss the prediction from three equation ofstate (EoS) including the entire baryon octet for warm stellarmatter. The EoS are compatible with the main constraintsfrom nuclear physics, both experimental and theoretical. Twoof the EoS are equally describing maximum mass 2M� forcold-equilibrated neutron stars of in agreement with recentobservations. We show that the density dependence of thesymmetry energy has a direct influence on the amount ofstrangeness inside hot and dense matter and consequentlyon thermodynamic quantities, e.g. the temperature for givenentropy per baryon [4]. We expect these differences to affectthe evolution of a protoneutron star or binary neutron starmergers. The presence of hyperons on the non-homogeneouswarm EoS will also be discussed [?].

* (FCT) Portugal1 CFisUC, Department of Physics, University of Coimbra, 3004-516

Coimbra, Portugal.

REFERENCES

[1] M. Fortin, C. Providencia, A. R. Raduta, F. Gulminelli, J. L Zdunik,P. Haensel, M. Bejger, Phys. Rev. C 94, 035804 (2016)

[2] M. Fortin, S. S. Avancini, C. Providłncia, I. Vidana, Phys. Rev. C 95,065803 (2017)

[3] Tuhin Malik, N. Alam, M. Fortin, C. Providłncia, B. K. Agrawal, T.K. Jha, Bharat Kumar, S. K. Patra, arXiv:1805.11963 [nucl-th]

[4] M. Fortin, M. Oertel, C. Providencia, arXiv:1711.09427 [astro-ph.HE][5] Dbora P. Menezes, Constana Providłncia, Phys. Rev. C 96, 045803

(2017)

0179

Development of the gaseous Xe scintillation detector for the particle

identification of high intensity and heavy RI beams

T.HaradaA,B, J.ZenihiroB, S.TerashimaB,C, Y.MatsudaB,D, H.SakaguchiE,

S.OtaF, M.DozonoF, K.KawataF, K.KasamatsuB,D, S.IshidaB,D

Toho Univ.A, RIKEN Nishina CenterB, Beihang Univ.C,

CYRIC, Tohoku Univ.DRCNP, Osaka Univ.E, CNS, Univ. of TokyoF,

abstract

For the experiments of unstable nuclei, the cocktail RI beams produced

by the fragmentation of HI beams are often used. It is necessary to

identify the RI beam event by event. RIBF can provide the high intense

RI beam, but we cannot fully utilize it due to the radiation damages of

the existing detectors for the particle identification. To get enough

data efficiently in a limited time, we need new detectors which have a

good radiation hardness, a fast timing response, and a good energy and

timing resolution.

For this purpose, we have developed a new detector employing the

scintillation of the gaseous Xe. Since Xe gas is known to have a small

work function, a high energy resolution is expected. However, the

scintillation properties of the gaseous Xe from high-energy and –

intensity HI particles not fully understood so far.

In order to evaluate the performance of the gaseous Xe scintillation

detector, we tested it with a primary beam of 136Xe 200Mev/u and a

secondary beam of A/Z ~2.28 at 300MeV/u produced by 132Xe 400MeV/u at

Heavy Ion Medical Accelerator in Chiba from Nov. 2017 to Feb. 2018. I

will report the result of this experiment in this conference.

0173

Status of Large-Acceptance Multipurpose Spectrometer at

RAON

Byungsik Hong

Department of Physics, Korea University, Seoul 02841, Republic of Korea

for the LAMPS Collaboration

A new radioactive ion beam accelerator RAON is being constructed at the

Institute for Basic Science (IBS) in Korea [1]. Among various experimental

devices, the large-acceptance multipurpose spectrometer (LAMPS) will be

available in the high-energy experimental hall of RAON. The main goal of the

LAMPS detector system is to investigate the nuclear equation of state and

symmetry energy at supra-saturation densities, which are essential to understand

the effective nuclear interactions and several astrophysical objects like neutron

stars [2].

In this presentation, various promising observables at RAON that are sensitive

to the nuclear symmetry energy are going to be discussed. Then, the status of the

development and construction of the detector elements, in particular the time-

projection chamber (TPC) and the forward neutron detector array, for the LAMPS

setup will be discussed.

[1] RISP homepage, http://www.risp.re.kr

[2] B. Hong et al., Eur. Phys. J. A 50, 49 (2014), DOI 10.1140/epja/i2014-14049-2.

0203

Plastic scintillator (PPO) with efficient neutron/gamma pulse shape discrimination.

Recently a new generation plastic scintillator (polyvinyltoluene PPO) has been developed and has shown an efficient pulse shape discrimination (PSD) neutron/gamma rays. These techniques used to distinguish between the pulses from neutrons and the pulses from gamma rays on the differences in the pulse shapes produced. The goal of this research effort was to test the ability of a PPO research sample to produce recordable, distinguishable signals in response to gamma rays and neutrons. A digital charge integration PSD algorithm has been studied. The results have been performed by using an Am-Be source and have been compared with different scintillators. Pulse shape analysis allowed the definition of a new Factor of Merit (FoM) as an indicative parameter for the neutron/gamma discrimination. The results of such separation are shown for EJ301 and EJ299.

0196

NN 2018 abstract

The NArCos Project

Emanuele V. Pagano for NewChim Collaboration

With the advent of the new facility for radioactive ion beams, in particular for the

neutron rich ones to the respect of the stable beams, it is necessary to develop

neutron detection systems integrated with the charged particle ones. The

integration of neutron signal, using neutron rich beams, became an important tool

in order to study the property of the nuclear matter in extreme conditions. For this

reason new detectors using new materials have to be build. In this contribution, it

will be presented the NArCoS (Neutron Array for Correlation Studies) project

having the purpose to construct a new detector to detect with high energy and

angular resolution both neutrons and charged particles in the same detection cell.

In the presentation, the first tests, efficiency, resolution and detection capabilities

will be presented.

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