A3F-CNS Summer School 2021

16 Aug 2021, 09:00 → 20 Aug 2021, 17:50 Asia/Tokyo

Dear Colleagues,

The 20th CNS International Summer School (CNSSS21), co-hosted by Center for Nuclear Study, the University of Tokyo and by JSPS A3 Foresight program, will be held for Aug.16 - Aug.20, 2020. The school is supported by RNC, Super Heavy Research Center of Kyushu Univ. and cooperated by ANPhA. 

The lecturers of the CNSSS21 include,

• Dr. Stefan Typel (GSI Germany) "From nuclei to stars with a relativistic density functional"

• Prof. Hidetoshi Yamaguchi (CNS, U. of Tokyo, Japan) "How to study nuclear clusters experimentally?"

• Prof. Peter Mueller (ANL, USA) "Atom Traps of Rare Isotopes at the Precision and Sensitivity Frontier in Nuclear Physics"

• Prof. Akira Ejiri (U. of Tokyo) " R&D for nuclear fusion reactors, High temperature plasma as a complex system"

• Dr. Zaihong Yang (RCNP, Osaka University, Japan) "Probing nuclear clustering with knockout reactions"

• Dr. Sarah Naimi (RIKEN Nishina Center, Japan) "Overview of RIBF"

• Prof. Susumu Shimoura (CNS, U. of Tokyo, Japan) "Direct reactions as quantum probes of sub-atomic system"

The registration opens now.

As the past CNSSS, we will have young scientist sessions where the Ph.D students and Post-docs contribute to oral presentation.  From 2018 we select a few persons from the poster and oral presentations as the winners of “CNSSS Young Scientist Awards”. The certificate will be given to the winners. For the best presentation, AAPPS-DNP/ANPhA award for young physisit is also presented.

 

We’re looking forward to seeing you at the school.

 

With best regards

A3F-CNSSS21  Organizing Committee

Monday, 16 August

1 opening

Speaker: Prof. Susumu Shimoura (CNS)

2 Atom Traps of Rare Isotopes at the Precision and Sensitivity Frontier in Nuclear Physics 1

Speaker: Prof. Peter Mueller (ANL)

10:50 break

3 Direct reactions as quantum probes of sub-atomic system 1

Speaker: Prof. Susumu Shimoura (CNS)

11:50 Lunch break

4 How to study nuclear clusters experimentally?

Speaker: Hidetoshi Yamaguchi (Center for Nuclear Study, the University of Tokyo)

14:20 break

5 From nuclei to stars with a relativistic density functional 1

Speaker: Dr Stefan Typel (GSI)

15:20 break

Young Scientist Session 1

6 Equation of States of Nuclear Matter and Tidal deformation of Neutron Star

The equation of states of (EoS) of the spin polarized, asymmetric nuclear matter (NM) is studied within the nonrelativistic Hartree-Fock (HF) formalism using realistic choices for the in-medium (density dependent) nucleon-nucleon (NN) interaction, dubbed as CDM3Y4, CDM3Y5, CDM3Y6 and CDM3Y8. Two scenarios for the density dependence of the spin polarization $\Delta$ of baryons in NM are considered, and the obtained HF results are compared with the empirical constraints for the nuclear symmetry energy given by the nuclear structure studies and the astrophysical observations of the binary NS merger (GW170817 and GW190425). A partial spin polarization of baryons ($\Delta < 1.0$) at low baryon densities seems more reasonable, with the HF results for the symmetry energy and incompressibility of NM being quite close to the empirical values. The mean-field based EoS of asymmetric NM is used further to construct the $\beta$-stable neutron star (NS) matter of strongly interacting baryons (protons and neutrons), electrons, and muons.

The EoS of NS matter over a wide range of baryon densities is used as input for the calculation of the macroscopic configuration of NS within the framework of General Relativity (GR), like the gravitational mass $M$, radius $R$, gravito-electric and gravito-magnetic tidal deformability. Given the empirical constrains inferred from the gravitational-wave signals of GW170817 and the mass limit of the heaviest pulsars observed, we conclude that the EoS of NS matter given by the CDM3Y6 and CDM3Y8 versions of the in-medium NN interaction is the most appropriate for the study of NS. The Love numbers of the tidal deformation of NS in a binary system are calculated up to the 4th order and a correlation of the tidal deformability of NS with its gravitational mass is shown.

Keywords: Neutron star, Magnetar, Spin polarization, Equation of state, Nuclear matter, Tidal deformability, Love number, Gravitational wave.

Speaker: Khoa Nguyen Hoang Dang (University of Science and Technology of Hanoi)

7 Extension of Migdal-Watson formula and its application to binary breakup reaction

Resonance phenomena appearing in low-energy nuclear reactions are very important in studies of nucleosynthesis in cosmos because reaction rates in the synthesis are strongly affected by the resonance parameters: resonance energy and decay width. In particular, the inelastic scattering to the continuum energy states above the particle decay threshold, which is often called breakup reaction, is very useful to explore the resonance parameters.
In order to derive the resonance parameters from the observed strength of the breakup reactions, the evaluation of the non-resonant background strength is indispensable because the resonant enhancement, which has the strong energy dependence, are embedded in the non-resonant background contribution with a broad structure. Since the background strength is structure-less and must have the weak energy dependence, the shape of the non-resonant background strength is often assumed by the simple analytic function or evaluated from the simple reaction mechanism, such as the direct breakup without the final state interaction between the decaying fragments. Unfortunately, there is no theoretical prescription to describe the non-resonant background strength on the basis of the simple analytic formula.
In this report, we propose an analytic formula to evaluate the non-resonant background strength by extending the Midgal-Watson (MW) theory [1], which was originally considered for the s-wave breakup reaction in the charge neutral systems [2-4]. In the evaluation of the background strength for the binary breakup, we employ the complex scaling method (CSM), which is a powerful tool to describe the few-body continuum states [5].
We have calculated the non-resonant breakup strength of $^{20}$Ne into $\alpha$ + $^{16}$O and $^{12}$Be into $\alpha$ + $^8$He by CSM, and the CSM strength is fitted by the analytic function, which is obtained by the extended MW formula. We will demonstrate that our analytic formula can nicely reproduce the non-resonant strength in these binary breakup reactions. Moreover, we will report the physical meaning of new parameters, which are introduced in extending the original MW formula, in connection to the spatial size of the initial wave function in the breakup reactions.

[1] R. Nakamoto, M. Ito, A, Saito and S. Shimoura, Phys. Rev. C, in press (2021).
[2] K. Watson, Phys. Rev. C88, 1163 (1952).
[3] A. Migdal, Sov. Phys. JETP 1, 2 (1955).
[4] S. Shimoura, Phys. Jour. Plus 133, 463 (2018).
[5] T.Myo et al. Prog, theor, phys,Vol.99, 5 (1998).

Speaker: Riu Nakamoto

8 Thermal blocking effect and pairing reentrance in excited odd nuclei

It has been well-known that the pairing correlations decrease with increasing temperature T. However, recent studies have reported a possible increase of pairing correlation in excited (hot) odd nuclei at low temperature (T < 0.5 – 1 MeV), which is associated to the pairing reentrance phenomenon [1, 2]. The latter has been explained due to the blocking effect of odd nucleon in odd nuclei at finite temperature. This blocking effect possibly depends on few single-particle levels above and below the Fermi surface where the odd nucleon can redistribute at nonzero temperature. In this study, we perform a systematic investigation of such a pairing reentrance in odd nuclei based on the exact solution of pairing problem at finite temperature. Our investigation starts with a simple doubly-folded multilevel pairing model by varying the energies of some single-particle levels above and below the Fermi surface. Calculations will be then extended to some calcium isotopes using a realistic axially deformed Woods-Saxon potential.

References
[1] N. Quang Hung, N. Dinh Dang, and L. T. Quynh Huong, Phys. Rev. C 94, 024341 (2016).
[2] Balaram Dey, Srijit Bhattacharya, Deepak Pandit, N. Dinh Dang, N. Ngoc Anh, L. Tan Phuc, and N. Quang Hung, Phys. Lett. B 819, 136445 (2021).

Speaker: Vu Dong Tran (VNUHCM - University of Science)

9 Theoretical analysis of mass and angle in the superheavy element region ~the possibility of the Z=120 element for fusion explored from the sticking time~

The next new superheavy element(SHE) locates the 8th period, is the notable element that provides the view on the existence of the predicted "island of stability (114-protons, 184-neutrons)" in the superheavy element region. In addition, neutron-rich nucleus far from the valley of stability in the nuclear chart are thought to have been produced by the r-process caused by supernova explosions and neutron mergers. The n-rich nucleus is important for understanding the origin of elements existing in the universe and the chemical evolution of the universe. For future SHE and n-rich nucleus synthesis, it is indispensable to propose a new method such as using the nucleon transfer reaction in addition to the conventional heavy ion fusion reaction, and to elucidate the reaction mechanism and the mechanism in the formation process. In this study, we focused on the nucleon transfer reactions. In the nucleon transfer reactions, the projectile nucleus receives nucleons from the target nucleus while rubbing around the target nucleus, increases the mass number, and the projectile-like fragment finally apart from the target-like fragment in the certain angle. At that time, there is a correlation between the number of transfer nucleons and the emission angle, and the characteristic differs depending on the projectile and target nucleus. The correlation between mass and angle of the fission fragment mass can understand the mechanism of fission and fusion process.
In this study, we calculated the mass angle distribution(MAD) using the dynamical model and investigated the correlation between mass and angle. As the result, it was possible to show that the correlation between mass and angle in the superheavy element region is different in the superheavy element region. In addition, we investigated the relationship between the fusion possibility for Z=120 and the sticking time from contact to scission.

Speaker: Shota Amano (Kindai University)

10 Time-Dependent Generator Coordinate Method for many-particle tunneling

Many-body tunneling is an important phenomenon in many fields of physics and chemistry.
In nuclear physics, tunneling effects appear, e.g., in low-energy fusion reactions, spontanious fission and so on.
The microscopic description of such tunneling effects is one of the major goals of nuclear reaction theory.

The time-dependent Hartree-Fock (TDHF) method, or the time-dependent density functional theory (TDDFT),
is one of the most widely used microscopic frameworks for nuclear reactions.
It has been demonstrated that the TDHF successfully describes average behaviors of nuclear reactions
such as the energy-angle correlation in heavy-ion deep inelastic collisions[1].
Because it is based on the nucleonic degrees of freedom,
ideally, the TDHF does not contain any empirical parameter for reactions, once static nuclear properties are well investigated.
This feature will be particularly important in applying the framework to unknown regions where experimental studies are difficult,
e.g., reactions of neutron-rich nuclei.

However, it has been known that the TDHF fails to describe tunneling effect. To overcome this problem, we will discuss the
Time-Dependent Generator Coordinate Method (TDGCM)[2-5] approach in this presentation.

In the TDGCM, one assumes that a many-body wave function is given as a superposition of many Slater determinants,
\begin{align}
\Psi(t)=\sum_af_a(t)\Phi_a(t)
\end{align}
where $f_a$ is a weight function and $\Phi_a$ is a Slater determinant. %with single-particle wave functions $\{\phi_{ai}\}$.
The index $a$ distinguishes each Slater determinant to one another, and is referred to as a generator coordinate.
The time evolution of the weight functions $f_a(t)$ and the Slater determinants $\Phi_a(t)$
are determined by the time-dependent variational principle.
We have applied this method to collision of an $\alpha$ particle on an external Gaussian barrier in one dimension.
In our calculation, the initial values of the center of mass position and momentum of the $\alpha$ particle
is taken as the generator coordinates.
We obtained the energy dependence of transmission probability.

\noindent [1]
A.K. Dhar, B.S. Nilsson, K.T.R. Davies, and S.E. Koonin, Nucl. Phys. {\bf A364}, 105 (1981). \
\noindent [2]
N. Hasegawa, K. Hagino and Y. Tanimura, Phys. Lett. {\bfseries B 808}, 135693 (2020).\
\noindent [3]
P.-G. Reinhard, R. Y. Cusson, and K. Goeke, Nuclear Physics A {\bf 398}, 141 (1983).\
\noindent [4]
E. Orestes, K. Capelle, A.B. da Silva, and C.A. Ullrich, J. Chem. Phys. {\bf 127}, 124101 (2007). \
\noindent [5]
J. Richert, D.M. Brink, and H.W. Weidenm\"uller, Phys. Lett. {\bf 87B}, 6 (1979).\

Speaker: Naoto Hasegawa (Tohoku univ.)

After Class Session 1: Introduction of Laboratories

11 OEDO/SHARAQ activitiy, CNS, Univ. of Tokyo

Speaker: Mr Jiatai Li (CNS)

12 Duy Tan University

Speaker: Dr Tan Phuc Le

13 Nuclear Experimental Group, Osaka University

Speaker: Mr Gen Takayama (Osaka univ.)

14 Nuclear Experimental group lab, Peking University

Speaker: Mr Lisheng Yang (Peking University)

15 Fundamental physics group, CNS Univ. of Tokyo

Speaker: Naoya Ozawa (Center for Nuclear Study, The University of Tokyo)

16 Nuclear Physics Lab.The University of Hong Kong

Speaker: Mr Yap Jinn Ming

17 Nuclear Theory group, Tokyo Institute of Tech

Speaker: Prof. Sekizawa Kazuyuki

Tuesday, 17 August

18 Atom Traps of Rare Isotopes at the Precision and Sensitivity Frontier in Nuclear Physics 2

Speaker: Prof. Peter Mueller (ANL)

10:50 break

19 How to study nuclear clusters experimentally? 2

Speaker: Hidetoshi Yamaguchi (Center for Nuclear Study, the University of Tokyo)

11:50 Lunch break

20 Direct reactions as quantum probes of sub-atomic system 2

Speaker: Prof. Susumu Shimoura (CNS)

14:20 break

21 From nuclei to stars with a relativistic density functional 2

Speaker: Dr Stefan Typel (GSI)

15:20 break

Young Scientist Session 2

22 Study of octupole correlations in neutron deficient nuclei having A<120 by means of lifetime measurement.

The nuclei having A ~120 (50 ≤ Z ≤ 56) are of considerable interest because of the competing shape driving tendencies of their orbitals occupied by the neutrons and the protons. Due to presence of both quadrupole and the octupole collectivity in the neutron deficient Ba, Cs and Xe nuclei with mass A ~ 120 have attracted much attention in recent years. For nuclei with A < 120, due to their closeness to the proton drip line and therefore difficulty to populate via fusion evaporation reactions, octupole collectivity has been reported in very few cases like $^{114, 116, 117}$Xe & $^{110}$Te [1,2]. In these reported cases also, there have been several ambiguities observed in the nature of octupole correlations. Like in $^{110}$Te, the measured B(E1) strengths (the most prominent experimental evidence considered for octupole correlations) are found to be in agreement when compared to those in the neutron-rich barium nuclei. However, when compared to $^{114, 116}$Xe, the B(E1) values in $^{110}$Te are found to be about an order of magnitude larger, thereby making the T$_{z}$ scaling of the dipole moment suggested in [1] questionable. Also, in case of $^{114}$Xe, the B(E1) value of the 5$^{-}$ $\rightarrow$ 6$^{+}$ transition is two orders of magnitude larger than that of 5$^{-}$ $\rightarrow$ 4$^{+}$ transition, thus contradicting a simple interpretation based on fixed intrinsic octupole deformation. Also, decoupling negative-parity bands observed in $^{118}$Xe are suggested to have octupole character at low spins but there is a need to be confirmed using lifetime measurements [3]. So, more experiments are needed to systematically investigate whether the octupole phenomenon is common in the A ~120 region. With this motivation, recently experiment was carried out to explore the high spin states in neutron deficient $^{118}$Xe nuclei via lifetime measurement using Doppler shift attenuation method (DSAM) technique at the Inter University Accelerator Centre (IUAC), Delhi. High spin states in $^{118}$Xe were populated using the $^{93}$Nb ($^{28}$Si, p2n) $^{118}$Xe fusion evaporation reaction at a beam energy of 115 MeV. The target consisted of nicely rolled 93Nb foil of thickness ~ 1.0 mg/cm$^{2}$ on 10 mg/cm$^{2}$ thick Pb backing. The de-exciting gamma rays were detected with the Indian National Gamma Array (INGA) setup [4], consisting of 16 Compton suppressed Clover detectors arranged in five rings at angles 32$^{◦}$, 57$^{◦}$, 90$^{◦}$, 123$^{◦}$, and 148$^{◦}$ with respect to the beam direction. Data was collected in γ - γ coincidences mode for the 9 shifts resulting in total number of counts acquired in γ-γ coincidence were 6*10$^{8}$. To optimize yield of $^{118}$Xe, excitation function was taken at 112, 115, 116 and 120 MeV of beam energy. A number of symmetric and asymmetric matrices were constructed by sorting gain matched list mode data. Lineshape analysis were carried out for some of the prominent transitions observed in yrast band, negative-parity band and interlinking transitions of E1 character. E1 character of these interlinking transitions are confirmed using angular correlation and linear polarization asymmetry ratio (∆$_{asym}$) measurements. These lineshape results would be further discussed in the seminar.
References:
[1] S. L. Rugari et al., Phys. Rev. C 48, 2078 (1993).
[2] E. S. Paul et al., Phys. Rev. C 50, R534 (1994).
[3] S. Tormanen, et al., Nuclear Physics A 572 417 – 458 (1994).
[4] S. Muralithar et al., Nucl. Instr. Meth. Phys. Res. A 622, 281 -287 (2010).

Speaker: Anand Pandey (University of Delhi)

Anand_A3f_CNSSS21_submission.pdf

23 12C + 12C fusion at low energies

Nuclear fusion reactions have very important significance in the area of nuclear astrophysics because they determine the nucleosynthesis of the elements in early stages of the universe and control the energy generation and evolution of stars. The precise knowledge of cross-sections and reaction rates of these nuclear fusion reactions are very important to describe the evolution of universe. There are various reactions which have strong significance in astrophysical aspects but our plan is to perform to experimentally study the 12C+12C fusion reaction at very low energies. This reaction is referred as carbon burning in stellar evolution process. Carbon burning plays a very important role in star which has mass greater than the eight solar mass (M > 8Mʘ). If mass is nearly 8Mʘ, then may end up as white dwarf and if mass is sufficiently larger than the 8Mʘ then it may show core-collapse supernovae.

Direct measurements of 12C+12C fusion cross sections have been performed over a wide range of energies by several researchers, but still the energy of interest for astrophysical purposes (Ecm <2MeV) has so far not been reached by direct measurement. Since the Gamow window for 12C+12C reaction (1-2 MeV) is much lower than its coulomb barrier (Ecm = 6.1 MeV), the direct measurement for this reaction is very challenging because of extremely small cross-sections. This becomes even more complicated owing to the high beam-induced background originating from impurities in target, especially, 1H and 2H. Lots of effort have been devoted to direct measurement of fusion cross section for this reaction, but so far could only go down to Ecm=2.1 MeV. Besides, the resonance which was found at  Ecm=2.1 MeV [1] remains questionable.

The indirect Trojan Horse Method was applied [2] to measure the astrophysical S-factor for 12C+12C fusion. A strong rise in astrophysical S-factor was reported at low energies, and also the S-factor at 2.1 MeV does not match with that of Ref. [1].  Subsequently, in Ref. [3], it has been claimed that for 12C+12C, astrophysical S-factor decreases at low energies, in contrast to Ref. [2].

In the light of the above scenario, it has become very important to measure the fusion cross sections of 12C+12C directly at low energies and also reduce the uncertainties of the existing measurements, as much as possible. With the upcoming unique FRENA facility at SINP, we plan to study the 12C+12C reaction at low energies. The off-line works that are needed before going for the actual measurement have been done. The present status of this reaction and the off-line works that we have done so far will be presented.

[1] T. Spillane et al., Phys. Rev. Letts, 98, 122501 (2007)

[2] A. Tumino et al., Nature 557, 687 (2018)

[3] A.M. Mukhamedzhanov et al, 99, 064618 (2019)

Speaker: Mr Ashish Gupta (SRF)

12C+12C fusion CNS school.pdf

24 Measurement of long-range two-particle correlations with ALICE

Measurements of long-range two-particle correlations have long provided critical insights into the properties of the matter created in heavy-ion collisions.
I will present results on long-range two-particle correlations for different charged particles multiplicities in pp at $\sqrt{s} = 13~\rm{TeV}$ and in p-Pb collisions at $\sqrt{s_{\rm NN}} = 5.02~\rm{TeV}$.
These measurements utilize the Forward Multiplicity Detector (FMD), which allows for unprecedented $\Delta\eta$ ranges to be explored (up to $\Delta\eta ~\sim 8$).
We will compare such measurements to predictions from the relativistic hydro model calculation that supposes the QGP and Monte Carlo generators, which helps us to understand the contribution from non-QGP-like processes in an unexplored kinematic regime.

Speaker: Yuko Sekiguchi (CNS)

25 Charge changing cross section and proton distribution radii of Be isotopes

In this research, we tested a new idea to measure proton-distribution radii ($r_{\rm{p}}$) by heavy-ion secondary beam experiments. It is important for understanding the structures of nuclei to know the proton- and the neutron-distribution radii independently. From this point of view, we tried to develop a new method to deduce proton-distribution radii ($r_{\rm{p}}$) very efficiently using nuclear collisions .

Now, $r_{\rm{p}}$ can be measured by electron scattering and isotope shift measurements. They have high accuracy and precision, but applicable unstable nuclei are rather limited. On the other hand, the present new method could have the same degrees of accuracy and could measure a wide range of unstable nuclei.

The experiment was carried out at HIMAC, Heavy Ion Medical Accelerator in Chiba, in Japan. We measured charge changing cross sections ($\sigma_{\rm{cc}}$) for $^{7-12}$Be isotopes on proton, Be, C, and Al targets. Charge changing cross section ($\sigma_{\rm{cc}}$) is the cross section of changing the number of protons in the collision with the target nucleus. We can deduce charge changing cross sections ($\sigma_{\rm{cc}}$) from the number of incident particles $N_1$ and charge changed particles $N_2$:

\begin{equation}
\sigma_{\rm{cc}}=-\frac{1}{t}\rm{ln}\Bigl(1-\it{\frac{N_2}{N_1}}\Bigr)
\end{equation}

In the zeroth-order approximation, charge changing reaction can be attributed to the abrasion of protons in the incident nucleus by nucleons in the target nucleus. A schematic drawing of this process is shown in figure 1. Thus it is approximated by equation (2).

\begin{equation}
\sigma_{\rm{cc}}=\pi(r_{\rm{T}}+r_{\rm{p}})^2
\end{equation}

![charge changing][1]

From eq (2), we can derive proton radii if target’s nucleon radius $r_{\rm{T}}$ and $\sigma_{\rm{cc}}$ are known. In practice, we need to use Glauber calculation with more realistic proton and neutron distributions both in the projectile and the target nuclei.

Thus, when trying to link the charge change cross-section and the proton distribution radius, the consideration of the proton evaporation process shown in fig. 2 is considered to be very important.
In this process, neutrons are firstly abraded, which excites prefragment and results in the evaporation of protons. If this process could be extracted independently, it would be very useful in deriving the proton-distribution radii from the charge change cross sections.

![proton evaporation][2]

In the experiment, we used proton, Be, C, and Al targets. Proton target is particularly sensitive to neutrons in the projectile reflecting the isospin asymmetry of the nucleon-nucleon total cross sections, which amplifies neutron abrasion. In short, the proton-evaporation effect has large portion of the charge changing cross section on proton target $\sigma^{\rm{p}}_{cc}$.

So, we assumed that $\sigma^{\rm{p}}_{cc}$ multiplied by some value x: $x\sigma^{\rm{p}}_{cc}$ is the cross section of proton evaporation for Be, C, and Al targets. Therefore, adding $x\sigma^{\rm{p}}_{cc}$ to eq (2) would reproduce the experimental results of charge changing cross sections.

In practice, we introduced x for each target and a constant parameter Y as the first and second approximation terms:

\begin{equation}
\sigma_{cc} = \sigma_{\rm{Glauber}} +
x\Bigl(\sigma^{\rm{p}}{\rm{cc}}-[\sigma^{\rm{p}}{\rm{Glauber}}+Y]\Bigr)
\end{equation}

As a result, we figured out that only 4 parameters, x(for 3 targets) and Y could reproduce 15 data of charge changing cross section for Be isotopes very well. It suggests a possibility of this new method for the deduction of proton-distribution radii with high accuracy and efficiency applicable to a wide range of unstable nuclei.

![proton distribution radii][3]

Speaker: Mr Gen Takayama (Osaka univ.)

26 In-beam γ-ray Spectroscopy of 97Cd

$^{100}$Sn (N=Z=50) and its neighboring nuclei have drawn great attention due to its possible doubly-magic nature and location around the proton drip-line. Being predicted as the end point of rp-process path, the properties of these nuclei also directly affect the synthesis of heavier elements. We therefore performed in-beam $\gamma$-ray spectroscopy of $^{100}$Sn and the neighboring nuclei using DALI2+ gamma-ray detection array at RIBF RIKEN. In this talk, we will present the measurement of $^{97}$Cd (N=49, Z=48). Preliminary level scheme of 97Cd and comparison of shell model calculations will be discussed.

Speaker: Mr Ting GAO (The University of Hong Kong)

97Cd_Ting_GAO_CNSSS21.pdf

27 The search for double Gamow-Teller giant resonance using double charge exchange reaction at RIBF

Understanding the nature of two sequential occurrences of the Gamow-Teller transition is important not only for the nuclear structure but also for the particle physics. However, there is little experimental information about the double Gamow-Teller transition at present. Especially, although the existence of a giant resonance state in double Gamow-Teller transition (Double Gamow-Teller Giant Resonance, DGTGR) has been theoretically predicted since 1989, it remains unobserved experimentally. The experimental data of DGTGR is suggested to restrict a value of a nuclear matrix element for the neutrinoless double beta decay, which is essential for the determination of the neutrino mass from the lifetime of the neutrino-less double beta decay.
A possible means to observe DGTGR is a heavy-ion double charge exchange reaction. We performed an experiment at RIBF using the ($^{12}$C, $^{12}$Be(0$^{+}_{2}$)) reaction. In this experiment, primary beam of $^{12}$C impinged reaction targets placed at F0 of BigRIPS separator. We used BigRIPS as a high precision spectrometer by measuring tracks of ejected particles at dispersive focal plane, F5.
We will see an overview of the experiment in the talk.

Speaker: Akane Sakaue (CNS)

Wednesday, 18 August

28 Atom Traps of Rare Isotopes at the Precision and Sensitivity Frontier in Nuclear Physics 3

Speaker: Prof. Peter Mueller (ANL)

10:50 break

29 How to study nuclear clusters experimentally? 3

Speaker: Hidetoshi Yamaguchi (Center for Nuclear Study, the University of Tokyo)

11:50 Lunch break

30 Probing nuclear clustering with knockout reactions

Speaker: Dr Zaihong Yang

14:20 break

31 From nuclei to stars with a relativistic density functional 3

Speaker: Dr Stefan Typel (GSI)

15:20 break

Young Scientist Session 3

32 Excitation of isobaric analog states from (p,n) and (3He,t) charge-exchange reactions within the G-matrix folding method

Differential cross sections of (p,n) and (3He,t) charge-exchange reactions leading to the excitation of the isobaric analog state (IAS) of the target nucleus are calculated with the distorted wave Born approximation. The G-matrix double-folding method is employed to determine the nucleus-nucleus optical potential within the framework of the Lane model. G matrices are obtained from a Brueckner-Hartree-Fock calculation using the Argonne Av18 nucleon-nucleon potential. Target densities have been taken from Skyrme-Hartree-Fock calculations which predict values for the neutron skin thickness of heavy nuclei compatible with current existing data. Calculations are compared with experimental data of the reactions (p,n)IAS on 14C at Elab = 135 MeV and 48Ca at Elab = 134 MeV and Elab = 160 MeV, and (3He,t)IAS on 58Ni, 90Zr, and 208Pb at Elab = 420 MeV. Experimental results are well described without the necessity of any rescaling of the strength of the optical potential. A clear improvement in the description of the differential cross sections for the (3He,t)IAS reactions on 58Ni and 90Zr targets is found when the neutron excess density is used to determine the transition densities. Our results show that the density and isospin dependences of the G matrices play a non-negligible role in the description of the experimental data.

Speaker: Nhut Huan Phan (Institute of Fundamental and Applied Sciences, Duy Tan University)

33 EFFECT OF LEVEL DENSITY PARAMETER IN THE DECAY DYNAMICS OF $^{12,13}C+^{12}C$ REACTIONS

The decay for number of compound nuclei formed in low energy heavy ion reactions have been successfully studied using dynamical cluster decay model (DCM) [R. K. Gupta, W. Scheid, C. Beck et al., Phys. Rev. C {68} (2003) 014610]. In a previous study the decay of $^{24,25}$${Mg}^*$ compound nuclei (CN) for the experimentally observed intermediate mass fragments (IMFs) that are $^{6,7}$Li and $^{7,8,9}$Be have been explored [Rupinder Kaur, Sarbjeet Kaur et al., Phys. Rev. C {101} (2020) 034614.] within DCM. The role of the $\alpha$-cluster structure of the complementary fragments was explored, which results in the enhanced preformation probability ($\Sigma P_{0}$) with respect to other fragments. These enhanced $\Sigma P_{0}$ values accordingly affect the yields of the respective IMF. In the present approach of DCM, we have extended this work to study the effect of level density parameter on the clustering effects of compound systems $^{24,25}$${Mg}^*$ formed via respective entrance channels namely $^{12}C+^{12}C$ and $^{13}C+^{12}C$, within the collective clusterization approach of Quantum Mechanical Fragmentation Theory (QMFT). The fragmentation and preformation profiles with the inclusion of level density parameter have been compared with the previous work at critical l value and for both the spherical and deformed configurations. The investigations show that by including modified level density parameter fragmentation profile, preformation profile and penetrability (P) are modified with small changes. But there is no major change in there cross section ratios. There is decrease in $\Sigma P_{0}$ but the enhancement in P accordingly affects the yields of the respective fragment. The calculated ratios of $\Sigma P_{0}$ of the IMFs show the trend of ratio of experimental cross sections and are in fair agreement with the experimental data [S. Manna, T. K. Rana, C. Bhattacharya et al., Phys. Rev. C {94} (2016) 051601(R)].

Speaker: Ms Sarbjeet Kaur (Sri Guru Granth Sahib world University)

34 Evolution of shell structure in neutron rich Cu and Ni nuclei

The evolution of shell structure with neutron and proton excess is a compelling interest in nuclear physics over the decade. The existence of the single-proton (single-neutron) shifts is well known experimentally in a series of isotopes (isotones) [1]. Although shell gaps, defined within a given theoretical framework as differences of effective single particle energies (ESPE), are not observables, they are useful quantities to assess the underlying structure of nuclei [2]. The nucleon-nucleon (NN) interaction is originally due to meson exchange processes as predicted by Yukawa, and its tensor-force part is one of the most distinct manifestations of this meson exchange origin [3]. The introduction of tensor force improved the systematic agreement between model predictions and experimental data in the shell evolution of exotic nuclei, and also the spin-orbit splitting [4]. A region of experimental interest nowadays is around the magic numbers Z=28 and N =50, where measurements of the decay properties in Co, Ni, Cu and Zn reveal the magic character of the nucleus 78Ni. The experimental results in Cu isotopes suggest that the crossing between the 2p3/2 and 1f5/2 proton levels take place in the nucleus 75Cu, which implies that the ground-state of 79Cu has spin-parity 5/2- [2]. It has been examined using different mean-field interactions such as Skyrme, Gogny and SEI-interactions that the tensor interaction may not always be necessary to reproduce the crossing between the 2p3/2 and 1f5/2 single-particle proton levels in neutron-rich Cu and Ni isotopes.
References
[1] N. A. Smirnova, et al Physical review C 69, 044306 (2004).
[2] L. Olivier et al, Phys. Rev. Lett. 119, 192501 (2017).
[3] T. Otsuka et al, Phys. Rev. Lett. 95, 232502 (2005).
[4] L. Guo et al, Physics Letters B 782 (2018) 401405.

Speaker: Ms Parveen Bano (School of Physics, Sambalpur University)

35 Visualization of nuclear cluster correlation with microscopic wave function

In general, the quantum many-body wave function obtained by theoretical calculation contains an enormous amount of information about many-body correlation. However, theoretical analyses in nuclear physics are mainly performed for quantities such as one- and two-body densities, which are obtained after integrating out most of the information in a many-body wave function.

On the other hand, in the field of quantum chemistry, methods have been developed to visualize the information on the correlation of all electrons and applied to the structure study of molecular systems[1]. We are now attempting to apply such a method to nuclear systems. As the first step, we start with finding the most probable arrangement of nucleon coordinates, i.e., calculating the set of position and spin coordinates that maximizes the square of the many-body wave function.

In this talk, we apply this method to Hartree-Fock and Hartree-Fock+BCS wave functions of p-shell and sd-shell nuclei. We found some alpha-cluster-like correlations out of the wave functions obtained without any assumption of cluster structure. We also discuss the effects of pairing correlation on the cluster structure by comparing the results between HF and HF+BCS.

[1] Yu Liu, Terry J. Frankcombe, and Timothy W. Schmidt, Phys. Chem. Chem. Phys. 18, 13385 (2016).

Speaker: Moemi Matsumoto (Tohoku University)

16:30 break

After Class session 2: Introduction of Laboratories

36 Super Heavy Element Group, Kyushu Univ.

Speaker: Mr Nagata Yuto (Kyushu University)

37 Nuclear Astrophysics group, Sungkyunkwan Univ.

Speaker: Minju Kim

38 Nuclear Astropysics Group CNS, Univ. of Tokyo

Speaker: Mr Hideki Shimizu (CNS, Univ. of Tokyo)

39 Nuclear Theory group, Univ. of Tokyo

Speaker: Mr Tomoya Naito (Department of Physics, The University of Tokyo/RIKEN Nishina Center)

40 Introduction of Beijing Normal University

Speaker: Ms Xinyue Li (Beijing Normal University)

41 Nuclear and Hadronic Physics Lab. Kyoto Univ.

Speakers: Mr Kanta Yahiro, Mr Kengo Ebata, Mr Ryosuke Yoshida

42 Universiti Teknologi Malysis

Speaker: Ms Mastura Syamimi

43 Can Tho University

Speaker: Mr Khoa Le Dang (Can Tho University)

44 Nuclear physics group, University of Delhi

Speaker: Mr Anand Pandey

Thursday, 19 August

45 Atom Traps of Rare Isotopes at the Precision and Sensitivity Frontier in Nuclear Physics 4

Speaker: Prof. Peter Mueller (ANL)

10:50 break

46 RIBF overview

Speaker: Dr Sarah Naimi (RIKEN Nishina Center)

11:50 Lunch break

47 Direct reactions as quantum probes of sub-atomic system 3

Speaker: Prof. Susumu Shimoura (CNS)

14:20 break

48 From nuclei to stars with a relativistic density functional 4

Speaker: Dr Stefan Typel (GSI)

15:20 break

Young Scientist Session 4

49 Nuclide identification algorithm for polyvinyl toluene scintillation detector based on artificial neural network

Radiation Portal Monitors (RPMs) are highly sensitive fixed installation systems designed to detect illicit radioactive material trafficking. RPMs are typically installed with detectors that have a high detection efficiency, such as plastic detectors. However, due to these detectors' limited energy resolution, radioisotope identification from their spectra is often not of interest. This research describes a radioisotope identification technique based on an artificial neural network that was applied to the gamma spectrum received from the large-size EJ-200 plastic detector. The simulated gamma spectra using MCNP-5 are used to generate the training data set. With an Exact Match Ratio of 98.8 percent, this method can precisely detect a single or mixture of radioisotopes in the gamma spectrum. In addition, the model can analyses gamma spectrum with up to 10% gain shift, up to 40° incident angle, and sealed source with good precision. This study also presents the model's sensitivity to each isotope in order to attain a True Positive rate of 95%. For radioisotopes detection, this model is usable on RPMs employing a large-size EJ-200 plastic scintillation detector.

Speaker: Mr Cao Van Hiep (Vietnam Military Institute of Chemical and Environmetal Engineering)

50 Performance of the CAT-TPC based on two-dimensional readout strips

A gas detector with a size of 140×140×140 mm$^3$, named the Compact Active Target Time Projection Chamber (CAT-TPC), has been developed aiming to measure resonant scattering associated with cluster structures in unstable nuclei. The CAT-TPC consists of an electronic field cage, double thick gas-electron-multiplier foils, a general purpose digital data acquisition system, and especially a newly developed two-dimensional strip-readout structure. The CAT-TPC was operated with $^4$He (96%) + CO$_2$ (4%) gas mixture at 400 mbar. The working gas also serves as an active target for tracking of charged particles. The overall performances of this CAT-TPC were evaluated by using a collimated alpha-particle source. A time resolution of less than 20 ns and a position resolution of less than 0.2 mm was observed along the electron drift direction. The three-dimensional images of incident trajectories and scattering events can be clearly reconstructed with an angular resolution of about 0.45 degree.

Speaker: Lisheng Yang (Peking University)

51 Compton reconstruction of the Crab under the atmospheric background for GRAMS balloon experiment

The GRAMS (Gamma-Ray and AntiMatter Survey) project that aims to observe MeV gamma rays and to search for dark matter at the same time started in 2021 on full scale. The MeV gamma-ray region is important for understanding phenomena in the universe such as nucleosynthesis and high-energy particle acceleration. The detector for the project is a large LArTPC (Liquid Argon Time Projection Chamber) with a size of 140 $\times$ 140 $\times$ 20 cm${}^3$, which works as a Compton camera. A balloon experiment using this detector is planned in the middle of the 2020s. There are a lot of background gamma rays in the atmosphere, so in the present work, the effect of the background in reconstruction of the Crab was evaluated. A Monte Carlo simulation to reproduce the detector response in the atmosphere was performed with ComptonSoft. Because of the computational limitations, the actual observation time corresponding to this simulation is only 100 seconds, but a clear reconstructed image of the Crab was obtained. The results demonstrated the feasibility to reconstruct MeV gamma ray images under atmospheric background and built the foundation for future data analysis.

Speaker: Kodai Okawa (CNS, the university of Tokyo)

52 ISGMR measurement in Xe isotope with CAT-M

The nuclear matter compressibility ($K_{\tau}$) is an important physical quantity that can directly determine a part of the equation of state of nuclear matter. In order to determine $K_{\tau}$ with high accuracy, it is indispensable to determine the compressibility of many nuclei ($K_{\mathrm{A}}$). We have been developing an active target CAT-M for the purpose of systematic measurement of an isoscalar giant monopole resonance (ISGMR).
In this study, we performed a ISGMR measurement using the $^{136}$Xe (d, d') reaction as the first measurement of systematic measurements with the Xe isotope. A dipole magnet was newly introduced into CAT-M for eliminate the delta rays by high intensity heavy ion beam in the experiment. Moreover a Mini TPC that has 10$\times$30$\times$30mm$^3$ active volume , was introduced for measure the beam angle. We will report the outline of the experiment.

Speaker: Fumitaka Endo (Tohoku Univ)

53 Search for permanent EDM using Fr atoms

The existence of the permanent Electric Dipole Moment (EDM) implies the time reversal symmetry violation. This violation directly means CP violation by the CPT theorem, and it would be expected to explain the observed matter-antimatter asymmetry.
The T-violation predicted by the Standard Model (SM) of particle physics for the electron EDM is too small to be measured with current experimental technique and the larger EDM would indicate a new physics beyond SM. This tiny effect of EDM can be enhanced by the relativistic effects in the heavy atoms such as francium (Fr).
In this talk, we will see the overview of the experimental setup of the search for EDM using laser cooled 221-Fr atoms, produced from the alpha decay of 225-Ac, which can be used as the generator for 221-Fr, and has a long lifetime ~ 10 days.
The 221-Fr nucleus has a large octupole deformation effect and can become the candidate to search for the nuclear EDM. The new experimental apparatus to produce the high intensity 225-Ac source, and laser cooling for 221-Fr is now developing. The present status will be discussed.

Speaker: Motoki Sato (University of Tokyo)

Friday, 20 August

54 How to study nuclear clusters experimentally? 4

Speaker: Hidetoshi Yamaguchi (Center for Nuclear Study, the University of Tokyo)

10:50 break

55 R&D for nuclear fusion reactors, High temperature plasma as a complex system 1

Speaker: Prof. Akira Ejiri

11:50 Lunch break

56 R&D for nuclear fusion reactors, High temperature plasma as a complex system 2

Speaker: Prof. Akira Ejiri

14:20 break

57 Direct reactions as quantum probes of sub-atomic system 4

Speaker: Prof. Susumu Shimoura (CNS)

58 Award ceremony

59 Closing