J. H. Kelley
North Carolina State University
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Featured researches published by J. H. Kelley.
Nuclear Physics | 1998
D. R. Tilley; C.M. Cheves; J. H. Kelley; S. Raman; H. R. Weller
Abstract Compilation of energy levels of A = 20 nuclei, with emphasis on the review of material leading to information about the structure of the A = 20 systems.
Journal of Applied Physics | 2009
C. A. Hagmann; J.M. Hall; Micah Johnson; D.P. McNabb; J. H. Kelley; C. Huibregtse; E. Kwan; G. Rusev; A. P. Tonchev
We provide a detailed experimental validation of the concept of transmission-based isotope detection. The dominant background processes in this class of systems were measured by studying the detection of U238 with a quasimonochromatic (ΔE∕E∼3%) photon beam. A notch develops in the spectrum transmitted through our test objects due to the preferential attenuation of photons with an energy that resonantly excites a bound nuclear state in U238 near 2 MeV. The notch was measured downstream of our test objects by means of resonant photon scattering from a secondary U238 target. The dominant backgrounds measured in the notch detector due to radioactive decay and elastic scattering of the transmitted beam are presented. Processes that refill the notch with off-resonance photons will obscure the signal and result in a higher probability of false negatives. A measurement of the refill process produced a null result, and we report an upper limit on the magnitude of the notch fill factor.
Physical Review C | 2001
D.J. Mercer; Sam M. Austin; J. A. Brown; S. Danczyk; S. E. Hirzebruch; J. H. Kelley; T. Suomijärvi; D. A. Roberts; T. P. Walker
Cross sections for production of 6He, 6Li, 7Li, and 7Be in the alpha+alpha reaction were measured at bombarding energies of 159.3, 279.6, and 619.8 MeV, and are found to decrease rapidly with increasing energy. These cross sections are essential for the calculation of the rate of nucleosynthesis of the lithium isotopes in the cosmic rays and thereby play a key role in our understanding of the synthesis of Li, Be, and B. The results for 6Li differ significantly from the tabulated values commonly used in cosmic-ray production calculations and lead to lower production of 6Li.
Physical Review Letters | 2014
R. Massarczyk; R. Schwengner; F. Dönau; S. Frauendorf; M. Anders; D. Bemmerer; R. Beyer; C. Bhatia; E. Birgersson; Maik Butterling; Z. Elekes; A. Ferrari; M. E. Gooden; R. Hannaske; A. R. Junghans; M. Kempe; J. H. Kelley; T. Kögler; A. Matic; M. Menzel; S. Müller; T. P. Reinhardt; M. Röder; G. Rusev; K. D. Schilling; Konrad Schmidt; G. Schramm; A. P. Tonchev; W. Tornow; A. Wagner
The electromagnetic dipole strength below the neutron-separation energy has been studied for the xenon isotopes with mass numbers A=124, 128, 132, and 134 in nuclear resonance fluorescence experiments using the γELBE bremsstrahlung facility at Helmholtz-Zentrum Dresden-Rossendorf and the HIγS facility at Triangle Universities Nuclear Laboratory Durham. The systematic study gained new information about the influence of the neutron excess as well as of nuclear deformation on the strength in the region of the pygmy dipole resonance. The results are compared with those obtained for the chain of molybdenum isotopes and with predictions of a random-phase approximation in a deformed basis. It turned out that the effect of nuclear deformation plays a minor role compared with the one caused by neutron excess. A global parametrization of the strength in terms of neutron and proton numbers allowed us to derive a formula capable of predicting the summed E1 strengths in the pygmy region for a wide mass range of nuclides.
Physical Review C | 2011
A. S. Adekola; C. T. Angell; S. L. Hammond; A. Hill; C.R. Howell; H. J. Karwowski; J. H. Kelley; E. Kwan
Properties of low-energy dipole states in {sup 232}Th have been investigated with the nuclear resonance fluorescence technique. The present work used monoenergetic {gamma}-ray beams at energies of 2-4 MeV from the high-intensity {gamma}-ray source at Triangle Universities Nuclear Laboratory. Over 40 transitions corresponding to deexcitation to the ground state and first excited state were observed for the first time. Excitation energies, integrated cross sections, decay widths, branching ratios, and transition strengths for those states in {sup 232}Th were determined and compared with quasiparticle random-phase-approximation calculations. A large number of E1 transitions were observed for the first time in actinide nuclei with summed strength of 3.28(69)x10{sup -3} e{sup 2} fm{sup 2}. The observed summed M1 strength of 4.26(63){mu}{sub N}{sup 2} is in good agreement with the other actinides and with the systematics of the scissors mode in deformed rare-earth nuclei.
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment | 2013
B. Löher; V. Derya; T. Aumann; J. Beller; N. Cooper; M. Duchêne; J. Endres; E. Fiori; J. Isaak; J. H. Kelley; M. Knörzer; N. Pietralla; C. Romig; D. Savran; M. Scheck; H. Scheit; J. Silva; A. P. Tonchev; W. Tornow; H. R. Weller; V. Werner; A. Zilges
The existing Nuclear Resonance Fluorescence (NRF) setup at the HI{\gamma}S facility at the Triangle Universities Nuclear Laboratory at Duke University has been extended in order to perform {\gamma}-{\gamma} coincidence experiments. The new setup combines large volume LaBr3:Ce detectors and high resolution HPGe detectors in a very close geometry to offer high efficiency, high energy resolution as well as high count rate capabilities at the same time. The combination of a highly efficient {\gamma}-ray spectroscopy setup with the mono-energetic high-intensity photon beam of HI{\gamma}S provides a worldwide unique experimental facility to investigate the {\gamma}-decay pattern of dipole excitations in atomic nuclei. The performance of the new setup has been assessed by studying the nucleus \sulfur at 8.125 MeV beam energy. The {\gamma}-decay branching ratio from the
Physics Letters B | 2017
A. P. Tonchev; N. Tsoneva; C. Bhatia; C.W. Arnold; Stéphane Goriely; S. L. Hammond; J. H. Kelley; E. Kwan; H. Lenske; J. Piekarewicz; R. Raut; G. Rusev; Toshiyuki Shizuma; W. Tornow
1^+
Physics Letters B | 1993
B. Young; D. Bazin; W. Benenson; J. H. Kelley; D. J. Morrissey; N. A. Orr; R. M. Ronningen; B. M. Sherrill; M. Steiner; M. Thoennessen; J. A. Winger; S. J. Yennello; Isao Tanihata; X.X. Bai; N. Inabe; T. Kubo; C.-B. Moon; S. Shimoura; T. Suzuki; Richard N. Boyd; K. Subotic
level at 8125.4 keV to the first excited
Physical Review C | 2003
A. P. Tonchev; S. O. Nelson; K. Sabourov; B. T. Crowley; K Joshi; H. R. Weller; J. H. Kelley; R. M. Prior; M. Spraker; N. Kalantar-Nayestanaki
2^+
Physical Review C | 2003
A. P. Tonchev; S. O. Nelson; K. Sabourov; M. Spraker; R. M. Prior; K. Joshi; H. R. Weller; N. Kalantar-Nayestanaki; J. H. Kelley; B. T. Crowley
state was determined to 15.7(3)%.