2018 2nd CHEA Workshop

January 17 (Wednesday) − 18 (Thursday), 2018

Jade Hall (B2, A Bldg.,)

Daemyung Resort Geoje Marina

2nd CHEA Workshop at Geojedo

January 17 (Wed) afternoon

1:15pm opening remark (Dongsu Ryu)

1:20 – 3:20: Chair Min Sup Hur

1:20 – 1:50 Allard J. van Marle: Combining Grid-MHD with the PIC method to simulate astrophysical shocks

1:50 – 2:20 Sunjung Kim: Spontaneous Emission of Electromagnetic Fluctuations in Kappa Magnetized Plasmas

2:20 – 2:35 Ji-Hoon Ha: Cosmic ray acceleration in weak ICM shocks

2:35 – 2:50 Soonyoung Roh: Magnetic fields in merging clusters of galaxies

2:50 – 3:05 Junseong Park: Numerical study of compressible isothermal MHD turbulence

3:05 – 3:20 Jihyun Kim: A close correlation between local galaxy filaments and UHE CRs of TA experiment

coffee break: 3:20- 3:40 pm

3:40 – 6:00: Chair Chae Un Kim

3:40 – 4:10 Lupin Lin: Studies on the Geminga-like pulsar, PSR J2021+4026.

4:10 – 4:30 David Hui: Spider Invasion across the Galaxy II

4:30 – 4:45 Kwangmin Oh: High energy observation of globular cluster

4:45 – 5:00 Jongsu Lee: X-ray Census of Millisecond Pulsars in the Galactic Field

5:00 – 5:15 Jeongkwan Yoon: Generating Automatic Network Reduction Module for Chemical Hydrodynamics Simulations

5:15 – 5:30 Seonho Kim: Ratio of Ruthenium Isotopes Predicted from Stellar Evolution Using the NuGrid Project

5:30 – 5:45 Minsik Kwag: THE 22Na(p,γ)23Mg REACTION RATE IN NOVA NUCLEOSYNTHESIS

5:45 – 6:00 Soomi Cha: Spectroscopy of the 21Na for the astrophysical 17F(α, p)20Ne reaction rate

January 18 (Thu) morning

8:30 – 10:25 Chair Moses Chung

8:30 – 8:50 Jungyeon Cho: Polarized emission from magnetically aligned dust grains

8:50 – 9:10 Maurice van Putten: Deep searches for broadband extended gravitational-wave emission

9:10 – 9:25 Chae-lin Hong: An exoplanetary system N-body simulator

9:25 – 9:40 Heesun Yoon: Statistical moments of density & column density for turbulence with different driving scales

9:40 – 9:55 Hyeseung Lee: Statistical study of turbulence from polarized synchrotron emission

9:55 – 10:10 Hanbyul Jang: Wave Families for Magnetohydrodynamic Fluids

10:10 – 10:25 Teyoun Kang: A sudden expansion of a thin plasma foil being irradiated by a circularly polarized laser

coffee break: 10:25- 10:40 pm

10:40 – 12:15 Chair Hyesung Kang

10:40 – 11:00 Chang-Hwan Lee: Tidal Love number & Deformability of NS and gravitational waves

11:00 – 11:15 Young-Min Kim: Tidal deformability of NS for various EoSs and its constraint by the observation

11:15 – 11:30 Myungkuk Kim: New Transport theory of Heavy-Ion collision in Low energy (DJBUU)

11:30 – 11:45 Sandeep Kumar: Magnetic field generation in a counterstreaming plasmas with anisotropic density distribution

11:45 – 12:00 SungNam Park: A Room-Temperature Miniaturized Electron Beam Ion Trap (mini-EBIT) for X-ray Spectroscopy of Highly-Charged Ions

12:00 – 12:15 Yoolim Cheon: Beam Loss Monitoring system at RAON for the rare isotope productions and experiments in nuclear astrophysics

12:15 Closing Remark

※ CHEA provides a dinner on the 17th and a breakfast on the 18th at B2F Restaurant (Columbus kitchen).

January 17 (Wednesday) - Session I

Combining Grid-Magnetohydrodynamics with the Particle-in-Cell method to simulate astrophysical shocks

Allard Jan van Marle (UNIST)

As a plasma passes through a shock, some particles are accelerated to high velocities through interaction with the local magnetic field. This interaction also causes instabilities and magnetic field amplification. In order to simulate this interaction, we need a code that is capable of both modelling the general shock structure (large scale) as well as the motion of individual particles (small scale). We achieve this by splitting the gas into two components:  A thermal component, representing the bulk of the plasma, which can be modelled with grid magnetohydrodynamics; and a non-thermal component, which represents the high velocity particles, and which is modelled with the Particle-in-Cell method. This approach allows us to include particle physics in a shock simulation while maintaining high computational efficiency. We present preliminary results of test simulations that reproduce the results achieved with more traditional codes, validating our method.

Spontaneous Emission of Electromagnetic Fluctuations in Kappa Magnetized Plasmas

Sunjung Kim (UNIST)

The present investigation formulates the theory of spontaneously emitted electromagnetic fluctuations in magnetized plasmas containing particles with an anisotropic suparthermal (bi-Kappa) velocity distribution function. The formalism is general applying for an arbitrary wave vector orientation and wave polarization, and for any wave-frequency range. As specific applications, the high-frequency electromagnetic fluctuations emitted in the upper-hybrid and multiple harmonic electron cyclotron frequency range are evaluated, and the fluctuations for low-frequency are also applied, which include the kinetic Alfvén, fast magnetosonic/whistler, kinetic slow mode, ion Bernstein cyclotron modes, and higher-order modes. The model predictions are consistent with particle-in-cell simulations. Effects of suprathermal electrons and ions on the fluctuations are studied by varying the power index, either [eqn: kappa _{i}]or [eqn: kappa _{e}]. It is found that both suprathermal electron and ion populations have important contributions to the emission spectra.

These results suggest that spontaneous fluctuations significantly contribute to the electromagnetic fluctuations observed in space plasmas, where suprathermal Kappa-distributed particles are ubiquitous.

January 17 (Wednesday) - Session I

Cosmic ray acceleration in weak ICM shocks

Ji-Hoon Ha (UNIST),

Dongsu Ryu (UNIST and KASI), Hyesung Kang (PNU)

Cosmic ray (CR) acceleration is mainly studied via Particle in Cell (PIC) and Hybrid simulations. Electrons can be accelerated in weak ICM quasi-perpendicular shock ([eqn: theta _{B} `>`45 DEG] and [eqn: M _{s} ` SIM `3])by Shock Drift Acceleration (SDA)[1]and observation of bright radio relics can be explained. But proton is not accelerated in weak ICM quasi-perpendicular shock since proton is scattered by MHD (Alfven) waves from proton injection but in quasi-perpendicular shock, proton injection is suppressed, so self-excited waves are hard to be induced. Protons are mainly accelerated in quasi-parallel shock ([eqn: theta _{BETA } `<`45 DEG]) by Diffusive Shock Acceleration (DSA). Previous studies of proton acceleration are mainly covered acceleration by Supernova Remnant (SNR) Shock ([eqn: MU _{s} >20]), these results are consistent with gamma ray observation from the SNR[2]. But proton acceleration in weak ICM quasi-parallel shock is poorly under stood.

Here, we perform PIC simulation for studying particle acceleration in weak ICM (plasma beta [eqn: beta SIM]20−100 and temperature [eqn: k TAU ` SIM 8.6keV]) shocks ([eqn: M _{s} ` SIM 3]). We argue that protons are also accelerated in weak ICM quasi-parallel shock. Thermal leakage injection and magnetic field amplification via plasma instabilities (resonant CR streaming instability and CR current driven instability) are main topic of this work.

References

[1] Guo et al. 2014, ApJ, 794, 153

[2] Caprioli & Spitkovsky 2014, ApJ, 783, 91

Magnetic fields in merging clusters of galaxies

Soonyoung Roh (UNIST)

The intracluster medium in clusters of galaxies is magnetized and magnetic fields play a critical role in the cluster formation and evolution. The existence of magnetic fields in clusters of galaxies is demonstrated by the rotation measure of polarized radio galaxies and the synchrotron emission of cluster-wide diffuse sources (radio halos and relics) as revealed in Coma cluster. A sausage relic is one of the Mpc-size giant radio relic detected in the ourskirts of the merging cluster, and its magnetic field strength in a few µG is derived for the radio emitting regions. The amplification and maintenance of the observed magnetic fields in the intracluster medium have established via turbulent dynamo. In this study, we investigate the configuration and strength of Mpc-size magnetic field in merging clusters of galaxies in three-dimensional numerical magnetohydrodynamical (MHD) simulations. For this, we assumed that the density profile of the intracluster gas in sporadically merging cluster is stratified.

January 17 (Wednesday) - Session I

Numerical study of compressible isothermal

magnetohydrodynamic turbulence

Junseong Park (UNIST)

MHD shocks are ubiquitous in astrophysical environments, and understanding how such shock structures form and their statistics in turbulent media is of great importance in astrophysics. The compressible MHD turbulence has three different types of shocks, namely the fast, intermediate and slow shocks. These shock waves increase the pressure and therefore compress the turbulent gas and increase its temperature, so they provide an important probe of physical conditions in the interstellar medium (ISM) and intracluster medium (ICM). Here we study compressible isothermal MHD turbulence in a variety of astrophysical environments by numerical simulations with resolution up to 10243. Our study covers both a wide range of turbulent Mach number (0.5 to 8) and plasma beta (0.1 to 10). We introduce a re ned methodology for detecting fast and slow shocks in MHD simulations and measure their distribution and Mach number.

A close correlation between local galaxy filaments and ultra-high-energy cosmic rays of Telescope Array experiment

Jihyun Kim (UNIST),

Dongsu Ryu, SukKim, Soo-ChangRey, Hyesung Kang

Since a clustering of ultra-high-energy cosmic ray (UHECR) events, so-called TA (Telescope Array) hotspot, was reported in 2014, its nature and origin have become one of issues to be addressed in astrophysics of UHECRs. Plausible source candidates around the TA hotspot area are far away on the sky, so a large deflection of trajectories by intervening magnetic fields is required to explain those events. However, it is not clear whether such large deflection could be consistent with the composition of TA UHECRs and observed galactic/extragalactic magnetic fields. We here report an investigation of the hypothesis that the TA hotspot is a consequence of the structures of the local universe. Specifically, we present a correlation study between filaments of galaxies in the local universe and the TA hotspotevents.

January 17 (Wednesday) - Session II

Studies on the Geminga-like pulsar, PSR J2021+4026.

Lupin C. C. Lin (UNIST)

PSR J2021+4026 located inside the SNR G78.2+2.1 is one of the gamma-ray pulsars detected through the blind search, and it is also the first variable gamma-ray pulsar detected by Fermi observatory. Because it has both X-ray and gamma-ray pulsation and lacks any radio emission, it was also classified as a member in the group of the “Geminga-like” pulsar. The PWN of this pulsar can also be captured by the Chandra observation.

In this talk, I will introduce the speciality of this pulsar, including its high-energy emitting feature and the change of the timing behavior during different flux levels. Comparing with the glitch investigated in other pulsars, the origin of the glitch of PSR J2021+4026 is a rare case and can be served as a special example to study the mode change of the radiation before and after the glitch.

Spider Invasion across the Galaxy II

David C. Y. Hui (CNU)

In this talk, I will review the progress of studying millisecond pulsars in the recent years and talk about the prospects of this topic in the near future.

January 17 (Wednesday) - Session II

High energy observation of globular culster

Kwangmin Oh (CNU)

Firstly, I will briefly present about the properties of gamma-ray emitting globular cluster. We set the 4 properties of gamma-ray globular cluster to compare and those were positively corelated with the gamma-ray luminosity. I will also show the result and process of classifying the x-ray sources in M62 with Chandra data.

X-ray Census of Millisecond Pulsars in the Galactic Field

Jongsu Lee (CNU)

We have performed the investigation for the properties of the selected millisecond pulsars (MSPs). Currently, the number of the detected X-ray MSPs is 47. We have normalized the X-ray properties of these MSPs into a homogeneous dataset. Also we have surveyed the upper limits of X-ray emission for the other 36 MSPs. We have investigated the correlation with spin-down power (Ė) between X-ray luminosity (Lx), magnetic field strength (B) and characteristic age (τ) and performed the statistical analysis. While we did not find any correlation for Bs, the strong correlations were found for Lx and Blc. Additionally, anti-correlation between Lx and τ was found. Furthermore, we divided our data samples into four classes. The differences between Redback and Black widow were found through the statistical test. This results indicate that redbacks are brighter and harder than black widows. Also the orbital period of redbacks and black widows are similar.

January 17 (Wednesday) - Session II

Generating Automatic Network Reduction Module for Chemical Hydrodynamics Simulations

Jeongkwan Yoon (UNIST), Kyujin Kwak(UNIST)

Since molecules exist in the interstellar cloud and they affect the hydrodynamic evolution through their formation and destruction, physical states of the actual interstellar cloud are different from calculations of conventional hydrodynamics simulations. Furthermore, in the case of running star-forming simulations, conventional hydrodynamics models are not enough to explain molecular lines emitted from clouds such as those detected from the ALMA observatory. In order to simulate the chemical evolution of a hydrodynamic cloud, building an efficient chemical network that contains relevant chemical reactions is crucial for cutting down the computation cost. A key factor for generating an efficient chemical network is to avoid using an abnormally small network that contains only a few reactions because using too small a network does not simulate the effects of molecules accurately. There already exist a few chemical hydrodynamics simulation codes, which provide pre-built reduced networks. Although those pre-built networks make the simulations simple and light, they work too strictly when some situations change, such as initial chemical compositions and environmental conditions. Therefore, it is necessary to build a more flexible network according to the conditions of the model. In this study, we make an automatic network-reducing module which builds an optimized closed network corresponding to the specific simulation conditions. We test our module in the test simulations of the primordial cloud by comparing our results with those obtained with the full network.

Ratio of Ruthenium Isotopes Predicted from Stellar Evolution Using the NuGrid Project

Seonho Kim (UNIST)

Abnormal ratios of ruthenium (Ru) isotopes in pre-solar grains are related to extinct technetium in stardust grains. Depending on the condition of mass and metallicity of the stellar evolution, the isotopes of Ru have different yields through the s, p, and r-process. NuGrid project calculates the nucleosynthesis of many heavy elements for a wide range of stellar mass and metallicity based on the MESA stellar evolution code. By using the NuGrid data, we check the ratio of Ru isotopes predicted from stellar evolution.

January 17 (Wednesday) - Session II

THE 22Na(p,γ)23Mg REACTION RATE IN NOVA NUCLEOSYNTHESIS

Minsik Kwag1,

K. Y. Chae1, S.Ahn2, D.W.Bardayan3, K.A.Chipps4, J.A.Cizewski5, M.E.Howard5,

R. L. Kozub6, K.Kwak7, B.Manning5, M.Matos8, P.D.O’Malley5, S.D.Pain9, W.A.Peters10, S.T.Pittman9,

A. Ratkiewicz5, M.S.Smith9, S.Strauss5

1Department of Physics, Sungkyunkwan University, Suwon, Korea

2Department of Physics and Astronomy, University of Tennessee, Knoxville, USA

3Department of Physics, University of Notre Dame, Notre Dame, USA

4Department of Physics, Colorado School of Mines, Golden, USA

5Department of Physics and Astronomy, Rutgers University, New Brunswick, USA

6Department of Physics, Tennessee Technological University, Cookeville, USA

7School of Natural Science, Ulsan National Institute of Science and Technology (UNIST), Ulsan, Korea

8Department of Physics and Astronomy, Louisiana State University, Baton Rouge, USA

9Physics Division, Oak Ridge National Laboratory, Oak Ridge, USA

10Oak Ridge Associated Universities, Oak Ridge, USA

22Na is one of the main sources of the galactic 1.275 MeV gamma-ray. The 22Na(p,γ)23Mg reaction rate plays a crucial role in understanding the production of 22Na during nova explosion. Since the 22Na(p,γ)23Mg reaction rate is determined by the resonance parameters of energy levels in 23Mg above the proton threshold located at 7.581 MeV, understanding the thermonuclear reaction at stellar temperatures is essential for astrophysical implications. The 24Mg(p,d)23Mg transfer reaction was measured at the Holifield Radioactive Ion Beam Facility of the Oak Ridge National Laboratory to study energy levels in radionuclide 23Mg. The spins and parities are constrained first time for the excited states located at E[eqn: {}_{chi }] = 8.038-, 8.324-, 8.430, and 8.920-MeV. By adopting newly updated 22Na(p,γ)23Mg reaction rate of the present work, it is concluded that the final abundance of 22Na is increased by 48% compared to that by using the reaction rate reported by Sallaska et al. for a 1.35 M[eqn: {}_{ODOT }] ONeMg white dwarf. Details of experimental method and result will be presented.

Spectroscopy of the 21Na for the astrophysical 17F(α, p)20Ne reaction rate

Soomi Cha (SKKU), K.Y.Chae (SKKU)

S. Ahn2, D.W.Bardayan3, K.A.Chipps4, J.A.Cizewski5, M.E.Howard5,, R.L.Kozub6, K.Kwak7, B.Manning5, M.Matos8, P.D.O’Malley5, S.D.Pain9, W.A.Peters10, S.T.Pittman9, A.Ratkiewicz5, M.S.Smith9 , S.Strauss5

1Department of Physics, Sungkyunkwan University, Suwon 16419, Korea

2Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA

3Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556, USA

4Department of Physics, Colorado School of Mines, Golden, Colorado 80401, USA

5Department of Physics and Astronomy, Rutgers University, New Brunswick, New Jersey 08903, USA

6Department of Physics, Tennessee Technological University, Cookeville, Tennessee 38505, USA

7Department of Physics, School of Natural Science, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Korea

8Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, USA

9Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA

10Oak Ridge Associated Universities, Oak Ridge, Tennessee 37831, USA

The 24Mg(p, α)21Na reaction has been measured at the Holifield Radioactive Ion Beam Facility (HRIBF) of the Oak Ridge National Laboratory (ORNL). A 31-MeV proton beam from the 25-MV tandem accelerator and the isotopically enriched 24Mg solid targets were used. Recoiling 4He particles were detected by a segmented silicon detector array in order to extract the angular distribution of the 24Mg(p, α)21Na reaction over a large angular range. Spins and parities of 21Na nuclide were constrained by comparing the experimentally extracted angular distributions and the Distorted Wave Born Approximation (DWBA) calculations. With these constraints the 17F(α, p)20Ne reaction rate, which affects the abundance evolution of 44Ti nuclide, could be calculated for the first time.

January 18 (Thursday) - Session Ⅰ

Polarized emission from magnetically aligned dust grains

Jungyeon Cho (CNU)

It is widely believed that magnetic fields play crucial roles for dynamics of molecular clouds and star formation processes. One of the most informative techniques of studying magnetic fields in astrophysical objects, such as molecular clouds and protostellar disks, is based on the use of polarized emission arising from magnetically aligned dust. In this talk, I will talk about basic physics of grain alignment and numerical methods of calculating polarized emission from aligned grains. As an application, I’ll briefly talk about polarized emission from protostellar disks.

Deep searches for broadband extended gravitational-wave emission

Maurice van Putten (Sejong University)

Back holes are leading candidates powering LGRBs, SGREEs and energetic core-collapse supernovae. Presented is an outlook on ascending and descending chirps from high-density accretion disks down to the ISCO of rapidly rotating black holes. Highlighted are searches by butterfly filtering using banks of up to 8 million templates on platform of Graphics Processor Units. This approach identifies an extended broadband Kolmogorov spectrum in LGRBs from BeppoSAX and faint H1L1 correlations in loudness and pitch in LIGO S6 of unknown origin. Future applications to GW170817 type events may reveal their association with magnetars or black holes.

January 18 (Thursday) - Session Ⅰ

An exoplanetary system N-body simulator

Chae-lin Hong (Sejong University)

We present a general N-body exasolar system simulator in anticipation of upcoming searches for exoplanets by next generation telescopes such as James Webb Space Telescope. For habitable zones, traditionally defined by temperature, we here address the problem of dynamical stability of planetary orbits. Illustrative examples are presented on P-type orbits in stellar binary systems, that should be fairly common as in Kepler 16b. Specific attention is paid to reduced orbital lifetimes of exoplanets in the habitable zone by the stellar binary, well known from Dvorak (1986).

Statistical moments of density and column density for turbulence with different driving scales

Heesun Yoon (CNU)

Probability distribution functions (PDFs) of the density provide the information of star formation, stellar initial mass function and core mass function. Therefore, it is important to study the density PDFs. The statistical quantities that can characterize the shape of the density PDFs are statistical moments. We study the relation between statistical moments (mean, standard deviation, skewness, and kurtosis) and turbulence driving scale for the different rms Mach numbers.

We focus on how the driving scale affects the relation between statistical moments and different driving scales.

January 18 (Thursday) - Session Ⅰ

Statistical study of turbulence from polarized synchrotron emission

Hyeseung Lee (CNU)

When turbulent motions perturb magnetic field lines and produce magnetic fluctuations, the perturbations leave imprints of turbulence statistics on magnetic field. Observation of synchrotron radiation is one of the easiest ways to study turbulent magnetic field. Therefore, we study statistical properties of synchrotron polarization emitted from media with MHD turbulence. First, we obtain the spatial spectrum and its derivative with respect to wavelength of synchrotron polarization arising from both synchrotron radiation and Faraday rotation. Second, we study quadrupole ratio to quantitatively describe the degree of anisotropy introduced by magnetic field at multi-wavelengths. In this study, we demonstrate that the spectrum and quadrupole ratio of synchrotron polarization can be very informative tools to get detailed information about the statistical properties of MHD turbulence from radio observations of diffuse synchrotron polarization.

Wave Families for Magnetohydrodynamic Fluids

Hanbyul Jang (UNIST)

Studying the waves in magnetohydrodynamic(MHD) is important to understand its underlying physics. There are 4 different wave modes for the MHD system; fast, slow, Alfven and entropy. We will demonstrate the characteristics of the MHD fluids through these waves and show how they can be used for numerical simulations.

January 18 (Thursday) - Session Ⅰ

A sudden expansion of a thin plasma foil being irradiated by a circularly polarized laser

Teyoun Kang (UNIST),

Young-Kuk Kim (UNIST), Min Sup Hur (UNIST)

Normally, a circularly polarized (CP) laser have been recommended to make a thin plasma layer, moving at a relativistic speed with a mono-energetic spread. The CP laser can compress and accelerate the layer stably, because of its slow-varying ponderomotive potential. However, in our recent particle-in-cell (PIC) simulation, we found a sudden expansion of the layer, irradiated by the CP laser. This unstable phenomena will decrease the energy density, and consequently the quality of the plasma layer. It is fatal effect, which kills the advantages of using a CP laser. In this presentation, we modified the previous theory about relativistic CP lasers. Our theory successfully explains the cause of the novel phenomena. Further, we suggested some recommended laser settings by one-dimensional PIC, so that the instability can be prevented.

January 18 (Thursday) - Session Ⅱ

Tidal Love number & Deformability of NS and gravitational waves

Chang-Hwan Lee (PNU)

Mergers of neutron star binaries are important because they can provide information on the equation of states of neutron stars, especially, the tidal Love number and deformability of neutron stars. These quantities have been measured by the gravitational waves from a binary neutron star merger, GW170817. In this talk, I will discuss the importance of gravitational waves in the study of neutron star structure.

Tidal deformability of NS for various EoSs and its constraint by the observation

Young-Min Kim (UNIST)

Multi-messenger observation of GW170817/GRB170817A/SSS17a(AT2017gfo) provided new contents on high energy astronomy/astrophysics. Among those, the upper limits of the tidal deformability of a neutron star (NS) observed by LIGO gaves us a new constraints on possible NS equations of states (EoSs). In this talk, I will show various results of the tidal deformabilities with various EoSs  and compare them with the recent observation of GW170817.

New Transport theory of Heavy-Ion collision in Low energy (DJBUU)

Myungkuk Kim (PNU)

Transport theory is one of the important approach to understand nuclear physical properties from heavy-ion collision experiment in low energy. Also, the rare isotope collision experiment facility such as RAON is under the construction in Korea. With these needs, we have developed a new Boltzmann-Uehling-Uhlenbecl (BUU) transport code named the DJBUU (DaeJeon Boltzmann-Uehling-Uhlenbeck). In this talk, I introduce the new transport code (DJBUU) and provide some results of heavy-ion collisions.

January 18 (Thursday) - Session Ⅱ

Magnetic field generation in a counterstreaming plasmas with anisotropic density distribution

Sandeep Kumar (UNIST),

Young-Kuk Kim (UNIST), Min-Sup Hur (UNIST), Moses Chung (UNIST)

Weibel instability (WI) driven by a counterstreaming plasmas with intrinsic kinetic anisotropies is studied via 2D particle-in-cell (PIC) simulation. Two counterstreaming electron-positron (e-/e+) plasmas are considered with anisotropic density distribution. Simulations show that in homogeneous distribution case, the magnetic field rapidly decays while in an inhomogeneous counterstreaming (e-/e+) plasmas the large magnetic fields appears in the later stage as the simulation progresses. A temperature anisotropy develops due to spatially anisotropic density structure in the later stage which makes the Weibel instability unstable. Simulations are carried out for different initial inhomogeneity of plasma density and for the mildly relativistic to ultra-relativistic drift velocities of counterstreaming e-/e+ plasmas. It is found that the evolution of the magnetic energy strongly depends on the initial inhomogeneity of the plasma density distribution and on the drift velocities of the e-/e+ plasmas. This study may help to understand the magnetic field generation in astrophysical sources i.e. gamma-ray bursts (GRBs) and SNRs where density fluctuations are common.

A Room-Temperature Miniaturized Electron Beam Ion Trap (mini-EBIT) for X-ray Spectroscopy of Highly-Charged Ions

SungNam Park (UNIST), Moses Chung (UNIST)

A miniaturized Electron Beam Ion Trap (mini-EBIT) can create, trap, and probe high charge states of most elements in the periodic table using 8 keV energy-tunable electron beam. Before the invention of the EBIT, only large facilities such as high energy accelerators and Tokamak fusion reactors can produce highly charged ions (HCIs). The compact, easily portable table-top mini-EBIT, with an off-axis electron gun and a 0.86 T room-temp permanent magnet, allows us to do X-ray spectroscopy of HCIs in a cost-effective and low-maintenance way. In this work, we present the status of the design and construction activities for the mini-EBIT underway at UNIST, in collaboration with Max-Planck Institute for Nuclear Physics in Germany.

January 18 (Thursday) - Session Ⅱ

Beam Loss Monitoring system at RAON for the rare isotope productions and experiments in nuclear astrophysics

Yoolim Cheon (UNIST),

Changkyu Sung (UNIST), Moses Chung (UNIST),

Yeonsei Chung (IBS), Gidong Kim (IBS), Hyung Joo Woo (IBS)

A heavy ion accelerator facility called RAON is being constructed in Daejeon, Korea to produce stable and exotic rare isotope beams of various energies for the Rare Isotope Science Project (RISP) of the Institute for Basic Science (IBS). The RAON will be equipped with two rare isotope production systems; Isotope Separation On-Line (ISOL) and In-Flight fragmentation (IF) systems. The ISOL system uses light (70 MeV proton) beam on high Z nuclear target, and the IF system uses heavy beams on low Z target to produce RI beams. Each end of the ISOL and IF systems is connected to various experiment systems. At the end of ISOL system, there are the KOrea Broad acceptance Recoil spectrometer and Apparatus (KOBRA) and the High Precision Mass Measurement System (HPMMS) for nuclear astrophysics research. At the end of IF system, the Large Acceptance Multi-Purpose Spectrometer (LAMPS) for the study of nuclear equation of state (EoS) and other applied science facilities are currently being developed.

RAON is expected to play an important role in nuclear astrophysics. Various experiments with high-intense RI beams and high performance experimental systems from RAON will contribute to understanding astrophysically important nuclear reactions carrying the nucleosynthetic processes and many elements formation in the cosmos.

The experimental systems from RAON can use both stable heavy ion beams and rare isotope beams to nuclear physics research. The low energy stable ions or RI beams ranged from a few to 18.5 MeV/u can be accelerated by superconducting linac SCL1 or 3. Also, they will be further accelerated through main driver linac SCL2 to reach up to a few hundreds of MeV/u, which can be used in IF system.

One of the biggest challenges in operating such a high beam power facility (~400 Kw) is to monitor beam loss accurately and to execute the Machine Protection System (MPS) reasonably quickly whenever necessary. When the beam loss occurs while the beam is accelerating along the

beam pipe, the lost particles hit the surface of the beam pipe and generate neutron and gamma rays. Then, we can detect the resulting radiation level using various kinds of Beam Loss Monitors (BLMs) to determine the moment to stop the accelerator system. Before we choose and construct the right BLM systems, we perform a Monte Carlo simulation using the MCNPX code to figure out the overall radiation level that can be used to estimate the approximate responses of the detectors based on their sensitivities. For BLMs, ACCT, Halo Monitor Ring (HMR), Proportional Counter (PC), and Plastic Detector (PD) can be used.

Participants List & Accommodation (Room information)

Family room

류동수, 강혜성

정모세

조정연

David Hui

Maurice van Putten

Lupin C. C. Lin

Allard Jan van Marle

Sandeep Kumar

이철, 김진균

임선우, 천유림

이혜승, 윤희선

오광민, 이종수

홍채린

차수미

곽민식, 김두현

윤정관, 김선호

엄자윤, 진주아

Suite room

김채운

이창환

김지현, 노순영, 장한별

김선정, 하지훈, 박준성

김영민, 김명국, 최용범

강태연, 박성남

Banquet & Breakfast

Buffet restaurant “Columbus Kitchen” (B2, A Building)

1. Banquet

- Date : Jan 17, Wednesday

- Time : 6:00 pm~

2. Breakfast

- Date : Jan 18, Thursday

- Time : 7:00 am ~ 11:00 am

* The convenience store and Starbucks Coffee are located on B2.