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Spectroscopic study of the radionuclide Na21 for the astrophysical F17(α,p)Ne20 reaction rate
Cha, S. M.,Chae, K. Y.,Ahn, S.,Bardayan, D. W.,Chipps, K. A.,Cizewski, J. A.,Howard, M. E.,Kozub, R. L.,Kwak, K.,Manning, B.,Matos, M.,O'Malley, P. D.,Pain, S. D.,Peters, W. A.,Pittman, S. T.,Ratkiewi American Physical Society 2017 Physical Review C Vol.96 No.2
<P>The Mg-24(p,alpha)Na-21 reaction was measured at the Holifield Radioactive Ion Beam Facility of the Oak Ridge National Laboratory to study the spectroscopy of the radionuclide Na-21. A 31-MeV proton beam from the 25 MV tandem accelerator bombarded isotopically enriched Mg-24 targets. Recoiling He-4 particles were identified by an annular silicon strip detector array. Two energy levels at E-x = 6.594 and 7.132 MeV were observed for the first time. By comparing the experimentally obtained angular distributions and distorted wave Born approximation calculations, the spins and parities of Na-21 energy levels were constrained. The astrophysicallyi-mportant F-17(alpha, p)Ne-20 reaction rate was also calculated for the first time using resonance parameters for 12 energy levels.</P>
Chae, K.Y.,Ahn, S.,Ayres, A.,Bardayan, D.W.,Bey, A.,Greife, U.,Howard, M.E.,Jones, K.L.,Kozub, R.L.,Matoš,, M.,Moazen, B.H.,Nesaraja, C.D.,O’Malley, P.D.,Peters, W.A.,Pittman, S.T.,Smith, M.S. Elsevier 2018 Nuclear Instruments & Methods in Physics Research. Vol.900 No.-
<P><B>Abstract</B></P> <P>Direct measurements of ( α , p ) reactions of astrophysical interest with radioactive beams presents serious challenges because of the difficult nature of helium targets and the typical low intensities of the beams. To address this, a new technique has been developed for measurements of low-energy ( α , p ) reactions with heavy ion beams using an extended <SUP> 4 </SUP> He gas target and a newly developed gas recirculating system. The system was used to measure the <SUP> 4 </SUP> He(<SUP>19</SUP>F, <SUP> 1 </SUP> H)<SUP>22</SUP>Ne reaction as a demonstration. Excitation functions of the <SUP>19</SUP>F( α , p )<SUP>22</SUP>Ne and <SUP>19</SUP>F( α , <SUP> p ′ </SUP> )<SUP>22</SUP>Ne <SUP> ∗ </SUP> reactions were successfully measured to show the viability of this technique. Details of the approach and future plans are given.</P>
First spin-parity constraint of the 306 keV resonance in Cl35 for nova nucleosynthesis
Chipps, K. A.,Pain, S. D.,Kozub, R. L.,Bardayan, D. W.,Cizewski, J. A.,Chae, K. Y.,Liang, J. F.,Matei, C.,Moazen, B. H.,Nesaraja, C. D.,O'Malley, P. D.,Peters, W. A.,Pittman, S. T.,Schmitt, K. T.,Smit American Physical Society 2017 Physical review. C Vol.95 No.4
<P>Of particular interest in astrophysics is the S-34(p,gamma) Cl-35 reaction, which serves as a stepping stone in thermonuclear runaway reaction chains during a nova explosion. Though the isotopes involved are all stable, the reaction rate of this significant step is not well known, due to a lack of experimental spectroscopic information on states within the Gamow window above the proton separation threshold of Cl-35. Measurements of level spins and parities provide input for the calculation of resonance strengths, which ultimately determine the astrophysical reaction rate of the S-34(p,gamma)Cl-35 proton capture reaction. By performing the Cl-37( p,t)Cl-35 reaction in normal kinematics at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory, we have conducted a study of the region of astrophysical interest in Cl-35, and have made the first-ever constraint on the spin and parity assignment for a level at 6677 +/- 15 keV (E-r = 306 keV), inside the Gamow window for novae.</P>
24Mg(p, α)21Na Reaction Study for Spectroscopy of 21Na
차수미,K. Y. Chae,김아람,E. J. Lee,S. Ahn,D. W. Bardayan,K. A. Chipps,J. A. Cizewski,M. E. Howard,B. Manning,P. D. O’Malley,A. Ratkiewicz,S. Strauss,R. L. Kozub,M. Matos,S. D. Pain,S. T. Pittman,M. S. Smith 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.67 No.8
The 24Mg(p, α)21Na reaction was measured at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory in order to better constrain the spins and parities of the energy levels in 21Na for the astrophysically important 17F(α, p)20Ne reaction rate calculation. 31-MeV proton beams from the 25-MV tandem accelerator and enriched 24Mg solid targets were used. Recoiling 4He particles from the 24Mg(p, α)21Na reaction were detected by a highly segmented silicon detector array which measured the yields of 4He particles over a range of angles simultaneously. A new level at 6661 ± 5 keV was observed in the present work. The extracted angular distributions for the first four levels of 21Na and the results from distorted wave Born approximation (DWBA) calculations were compared to verify and extract the angular momentum transfer.
Gu G. M.,Chae K. Y.,Cha S. M.,Kwag M. S.,Kim M. J.,Allen J.,O’Malley P. D.,Boeltzig A.,Clark A. M.,Frentz B.,Kolk B. V.,Blankstein D.,Bardayan D. W.,Wilkinson J.,Seymour G.,Howard K. B.,Renaud M.,Hall 한국물리학회 2024 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.85 No.3
The 24Mg(훼,p) 27Al reaction was measured using the solenoid spectrometer for nuclear astrophysics at the University of the Notre Dame to study the astrophysical 24Mg(훼,p) 27Al reaction rate. Alpha beams from the 10-MV FN tandem accelerator impinged on 24Mg solid targets which were made using the vacuum evaporation method on 12C foils. A total of 43 beam energies were used. Recoiling protons from the 24Mg(훼,p) 27Al reaction were detected using a double-sided position sensitive silicon detector array mounted on the solenoid. Energies, times of fight, and fight distances of particles were measured for particle identifcation. Protons associated with a wide range of excitation energies Ex = 12.42–14.44 MeV in 28Si were identifed.
Proton Decay of 21Na for 20Ne Energy Levels
Kim M. J.,Chae K. Y.,Cha S. M.,Ahn S. H.,Bardayan D. W.,Chipps K. A.,Cizewski J. A.,Howard M. E.,Manning B.,Ratkiewicz A.,Kozub R. L.,Kwak K.,Matos M.,O’Malley P. D.,Strauss S.,Pain S. D.,Pittman S. T 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.77 No.5
The 24Mg(p,α)21Na transfer reaction has been previously studied for a spectroscopic study of 21Na [Cha et al., Phys. Rev. C 96, 025810 (2017)]. In this follow-up analysis, the proton decays of the excited states of the radionuclide 21Na, which were measured simultaneously, are reported. By investigating the coincidence between the reaction α-particles and decay protons, we were able to identify three groups of events that are associated with the energy levels in 20Ne. The 20Ne excitation energy plot was obtained as a result. The four lowest known energy levels in 20Ne (the ground state and excited states at Ex = 1.633, 4.247 and 4.966 MeV) were clearly observed.