Background Considerations for the 2H(7Be,3H)6Be Experimental Data II: Three-body Continuum

채경육,V. Guimar˜aes 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.67 No.9

The present article reports second background considerations for the experimentally obtained 2H(7Be,3H)6Be differential cross sections. The one-neutron transfer reaction was measured in inverse kinematics by using radioactive 7Be (t1/2 = 53.2 days) beams at the Holifield Radioactive Ion Beam Facility of the Oak Ridge National Laboratory in 2004 in order to search for the resonances in the unbound 6Be nucleus. Resonances in this nucleus would affect the 3He(3He,2p)4He reaction rate of the proton-proton chain occurring in stars such as our sun. The result shows, however, that the direct transfer to 6Be resonances is not particularly strong compared to other reaction channels that can produce tritons in the exit channels. The goals of the present work is to better understand the cross section data from transfer reaction measurements by adopting background considerations using the three-body continuum.

양성자 빔과 $^{24}$Mg 표적을 이용한 방사성 핵종 $^{23}$Mg의 핵구조 연구

채경육,곽민식,이은지,곽규진 한국물리학회 2016 새물리 Vol.66 No.12

The energy levels of the $^{23}$Mg radionuclide are very important for astrophysical reactions such as the $^{22}$Na($p$,$\gamma$)$^{23}$Mg and the $^{19}$Ne($\alpha$,$\gamma$)$^{23}$Mg reactions, depending on their excitation energies. In the present manuscript, two independent $^{24}$Mg($p$,$d$)$^{23}$Mg transfer reaction measurements, which were performed by using 31- and 41-MeV proton beams from the Holifield Radioactive Ion Beam Facility of the Oak Ridge National Laboratory in the United States and $^{24}$Mg solid targets, are summarized. Recoiling deuterons from the ($p$,$d$) reactions were detected by using a silicon strip detector array. By comparing the experimental angular distributions with the results of calculations using theoretical distorted-wave Born approximation, we were able, for the first time, to constrain the spins and the parities of seven energy levels in $^{23}$Mg. 방사성 핵종 $^{23}$Mg의 에너지 레벨은 그 위치에 따라 $^{22}$Na($p$,$\gamma$)$^{23}$Mg 및 $^{19}$Ne($\alpha$,$\gamma$)$^{23}$Mg와 같은 천체물리학적으로 의미있는 핵반응의 이해에 매우 중요한 역할을 한다. 본 논문에서는 미국 Oak Ridge National Laboratory의 Holifield Radioactive Ion Beam Facility에서 생성 및 가속한 31과 41 MeV의 양성자 빔 및 $^{24}$Mg 고체 표적을 이용하여 수행한 두 건의 $^{24}$Mg($p$,$d$)$^{23}$Mg 핵자 전달반응 측정 결과를 소개한다. ($p$,$d$) 핵반응의 결과로 생성된 중양자를 실리콘 검출 시스템으로 관찰하였다. 실험적으로 얻은 중양자의 각분포와 찌그러진 파동 보른 근사법 (distorted wave Born approximation, DWBA) 계산 결과를 비교하여 총 7개의 $^{23}$Mg 에너지 레벨에 대한 스핀과 패러티를 최초로 규명하였다.

Searching for Resonances in the Unbound 6Be Nucleus by Using a Radioactive 7Be Beam

채경육,D. W. Bardayan,J. C. Blackmon,M. S. Smith,A. E. Champagne,J. J. Das,R. P. Fitzgerald,D. W. Visser,V. Guimaraes,K. L. Jones,S. D. Pain,J. S. Thomas,M. S. Johnson,R. L. Kozub,R. J. Livesay,Z. Ma,C. 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.61 No.11

Knowledge of the ³He(³He,²<i>p</i>)⁴He reaction is important for understanding stellar burning and solar neutrino production. Previous measurements have found a surprisingly large rise in the cross section at low energies that could be due to a low-energy resonance in the ³He + ³He (⁶Be) system or electron screening. In the ⁶Be nucleus, however, no excited states have been observed above the first 2⁺ state at <i>E_x</i> = 1.67 MeV up to 23 MeV, even though several are expected. The ²H(⁷Be,³H)⁶Be reaction has been studied for the first time to search for resonances in the ⁶Be nucleus that may affect our understanding of the ³He(³He,²<i>p,</i>)⁴He reaction. A 100-MeV radioactive ⁷Be beam from the Holifield Radioactive Ion Beam Facility (HRIBF) was used to bombard CD₂ targets, and tritons were detected by using the silicon detector array (SIDAR). A combination of reaction mechanisms appears to be necessary to explain the observed triton energy spectrum.

Development of a Portable Gas-filled Ionization Chamber

채경육,차수미,M. S. Gwak 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.64 No.4

A new portable gas-filled ionization chamber has been designed and constructed at the PhysicsDepartment of Sung Kyun Kwan University. To overcome the maximum count rate of 105particles per second of a conventional ionization chamber, which utilizes a Frisch grid, and toenhance the portability of a detector, we adopted the design of multiple electrodes and modifiedit from the original designs by Kimura et al. and Chae et al. The new design utilizes a stack ofmultiple electrodes installed perpendicular to the optical beam axis. This configuration providesa fast response time for the detector, which is essential for high-rate counting. The device hasbeen tested with a 241Am (t1/2 = 432.2 years) radioactive source, which mainly emits 5.486-MeV(branching ratio of 85%) and 5.443-MeV (branching ratio of 13%) particles. An energy resolutionof 6.3% was achieved.

희귀동위원소 핵반응에 따른 엑스선폭발 광도곡선 변화

박병찬,곽규진,채경육,김아람 한국물리학회 2016 새물리 Vol.66 No.12

엑스선폭발 (X-ray Bursts)은 중성자별 표면에서 발생하는 열핵반응폭주에 의해 발생하는 것으로 알려져 있다. 이러한 열핵반응폭주는 중성자별 표면으로 유입되는 물질의 유입율 및 금속함량과 열핵반응폭주에 참여하는 원자핵의 핵반응에 따라 달라진다. 이번 연구에서는 세가지 특정한 반응인 삼중알파, $^{18}\mbox{Ne}(\alpha,p)^{21}\mbox{Na}$, $^{15}\mbox{O}(\alpha,\gamma)^{19}\mbox{Ne}$ 핵반응율에 따라 엑스선폭발의 광도 곡선 모양이 어떻게 변화하는지를 조사하였다. 연구의 결과로 광도 곡선의 형태가 같은 반응의 서로 다른 반응율에 따라 변화하는 것을 확인하였지만 54개 동위원소를 포함한 반응망을 가지고 계산한 광도 곡선 모양은 반응율에 따른 변화를 고려하더라도 여전히 실제 관측된 광도 곡선과 큰 차이를 보였다. 이전 연구에서처럼 광도 곡선의 모양은 열핵반응폭주에 참여하는 원자핵의 갯수에 더 큰 영향을 받는다는 것을 확인하였다. X-ray bursts (XRBs) have been thought to occur via thermonuclear runaway reactions on the surface of a neutron star. The runaway reactions are affected by both the properties of the accreted material, such as the accretion rate and the composition, and the reaction rates of participating nuclei. We investigate how the shape of the XRB light curve changes with specific reaction rates. As a case study, we choose three reaction rates, triple alpha, $^{18}\mbox{Ne}(\alpha,p)^{21}\mbox{Na}$, and $^{15}\mbox{O}(\alpha,\gamma)^{19}\mbox{Ne}$. We find that the shape of the light curve does change with different reaction rates for the same reaction, but the predicted light curves with 54 isotopes do not match the observed ones even when the variations within the different reaction rates are considered. We confirm that the shape of the light curve is more sensitive to the number of isotopes that participate in the runaway reactions.

Construction and Commissioning of a Position-Sensitive Ionization Chamber

M. S. Kwag,채경육,차수미,김아람,M. J. Kim,E. J. Lee,J. H. Lee 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.68 No.10

A position-sensitive ionization chamber has been constructed and commissioned at the Physics Department of Sungkyunkwan University to extract position information on incident charged particles for future nuclear reaction measurements. By utilizing the newly-designed position-sensitive anodes and the previously-commissioned portable gas-filled ionization chamber by Chae et al., position information on incident particles could be obtained. The device was tested with an 241Am -emitting source, and the standard deviation of the fitted Gaussian distribution was measured to be 1.76 mm when a collimator with a 2 mm hole was used.

Development and Performance Test of the Analysis Software for the CRIB Active Target

이필수,이춘식,문준영,채경육,차수미,Hidetoshi Yamaguchi,Taro Nakao,David M. Kahl,Shigeru Kubono,Silvio Cherubini,Seiya Hayakawa,Cosimo Signorini 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.66 No.3

Software for genuinely event-by-event analysis and event reconstruction of data obtained by usingan active target has been developed in the graphical user interface under the CERN ROOT framework. The primary motivation for developing the software was to provide physicists who performexperiments using an active target a more user-friendly environment for the purpose of investigatingthe performance of detection systems and obtaining ideas about physics from a large amount ofexperimental data. To test the performance of the software, we analyzed experimental data froma 16N radioactive ion beam experiment for α-decay measurements. As a result of the analysis, weobserved the Bragg curve and measured the range of the 16N RI beam in the detector. Data werecalibrated against the calculation after comparing the Bragg curve to the one obtained from anenergy loss calculation in P-10 gas. We present a detailed description of the analysis software andits test results.

Measuring one Nucleon Transfer Reaction 24Mg(p; d)23Mg for Astrophysical Reaction Rates

E. J. Lee,채경육 한국물리학회 2017 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.71 No.11

The level structure of a radionuclide 23Mg has been studied by using the 24Mg(p; d)23Mg one nucleon transfer reaction measurement for the astrophysical 19Ne(®; °)23Mg reaction rate. A 41 MeV proton beam was produced and accelerated at the 25 MV tandem accelerator of the Holi¯eld Radioactive Ion Beam Facility of the Oak Ridge National Laboratory in the United States. The beam particles impinged on an isotopically-enriched 24Mg solid target. Angular distributions of recoiling deuterons were extracted by using a large area silicon strip detector array. By comparing the experimentally-obtained angular distributions with zero range distorted wave Born approxima- tion calculations, spins and parities of three energy levels of 23Mg could be constrained for the ¯rst time, which is very important information needed to understand the 19Ne(®; °)23Mg reaction rate.

Multi-Electrode Ionization Chamber Energy Loss Calculator (MICE)

M. J. Kim,채경육 한국물리학회 2017 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.70 No.10

A gas-filled ionization chamber is well suited for low energy nuclear physics applications such as measuring beam intensities and detecting heavy recoils from nuclear reactions. Recently developed multi-electrode ionization chamber shows great performance in terms of the energy resolution and the maximum counting rate. It requires, however, iterative energy loss calculations for certain applications mainly due to its complex geometry. For easier energy loss calculations, a stopping power calculation code called the Multi-electrode Ionization Chamber Energy Loss Calculator (MICE) has been developed by utilizing the Java programming language. The development procedure, usage, and application of the MICE are reported.

MRTOF-S: a toolkit for pre-estimating precise mass measurements using MRTOF spectrometer

Duy Nguyen Ngoc,Uyen Nguyen Kim,채경육 한국물리학회 2022 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.80 No.9

An accurate estimation of the masses of exotic nuclei is important for obtaining a better understanding of the nuclear structure and for astrophysical calculations. Because most nuclear masses of unstable isotopes far from beta stability are highly uncertain, precise mass measurements are necessary. Among recent advanced techniques, the multiple-reflection time-of-flight (MRTOF) has emerged as a good device for measuring the precise masses of short-lived isotopes with high mass-resolving power. Before conducting mass measurements in laboratories, it is necessary to pre-estimate the beam production rate, separability of ions, mass resolving power, etc. Hence, a computer code named MRTOF simulator (MRTOF-S) was developed. In this study, we report the development procedure, usage, and application of the MRTOF-S toolkit.