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Title: Study of low-lying resonant states in 16F using an 15O radioactiveion beam

Abstract

A 120 MeV {sup 15}O radioactive ion beam with an intensity on target of 4.5 x 10{sup 4} pps has been developed at the 88-inch cyclotron at the Lawrence Berkeley National Laboratory. This beam has been used to study the level structure of {sup 16}F at low energies via the p({sup 15}O,p) reaction using the thick target inverse kinematics method on a polyethylene target. The experimental excitation function was analyzed using R-matrix calculations. Significantly improved values for the level widths of the four low-lying states in 16F are reported. Good agreement with the theoretical spectroscopic factors is also obtained.

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Ernest Orlando Lawrence Berkeley NationalLaboratory, Berkeley, CA (US)
Sponsoring Org.:
USDOE Director. Office of Science. NuclearPhysics
OSTI Identifier:
928776
Report Number(s):
LBNL-62332
R&D Project: 464501; BnR: KB0401022; TRN: US0803260
DOE Contract Number:
DE-AC02-05CH11231
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review C: Nuclear Physics; Journal Volume: 76; Journal Issue: 2; Related Information: Journal Publication Date: 08/2007
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; CYCLOTRONS; EXCITATION FUNCTIONS; LEVEL WIDTHS; POLYETHYLENES; R MATRIX; RADIOACTIVE ION BEAMS; SPECTROSCOPIC FACTORS; TARGETS

Citation Formats

Lee, D.W., Perajarvi, K., Powell, J., O'Neil, J.P., Moltz, D.M., Goldberg, V.Z., and Cerny, Joseph. Study of low-lying resonant states in 16F using an 15O radioactiveion beam. United States: N. p., 2007. Web. doi:10.1103/PhysRevC.76.024314.
Lee, D.W., Perajarvi, K., Powell, J., O'Neil, J.P., Moltz, D.M., Goldberg, V.Z., & Cerny, Joseph. Study of low-lying resonant states in 16F using an 15O radioactiveion beam. United States. doi:10.1103/PhysRevC.76.024314.
Lee, D.W., Perajarvi, K., Powell, J., O'Neil, J.P., Moltz, D.M., Goldberg, V.Z., and Cerny, Joseph. Mon . "Study of low-lying resonant states in 16F using an 15O radioactiveion beam". United States. doi:10.1103/PhysRevC.76.024314. https://www.osti.gov/servlets/purl/928776.
@article{osti_928776,
title = {Study of low-lying resonant states in 16F using an 15O radioactiveion beam},
author = {Lee, D.W. and Perajarvi, K. and Powell, J. and O'Neil, J.P. and Moltz, D.M. and Goldberg, V.Z. and Cerny, Joseph},
abstractNote = {A 120 MeV {sup 15}O radioactive ion beam with an intensity on target of 4.5 x 10{sup 4} pps has been developed at the 88-inch cyclotron at the Lawrence Berkeley National Laboratory. This beam has been used to study the level structure of {sup 16}F at low energies via the p({sup 15}O,p) reaction using the thick target inverse kinematics method on a polyethylene target. The experimental excitation function was analyzed using R-matrix calculations. Significantly improved values for the level widths of the four low-lying states in 16F are reported. Good agreement with the theoretical spectroscopic factors is also obtained.},
doi = {10.1103/PhysRevC.76.024314},
journal = {Physical Review C: Nuclear Physics},
number = 2,
volume = 76,
place = {United States},
year = {Mon Jan 22 00:00:00 EST 2007},
month = {Mon Jan 22 00:00:00 EST 2007}
}
  • A 120 MeV {sup 15}O radioactive ion beam with an intensity on target of 4.5x10{sup 4} pps has been developed at the 88-Inch Cyclotron at the Lawrence Berkeley National Laboratory. This beam has been used to study the level structure of {sup 16}F at low energies via the p({sup 15}O, p) reaction using the thick target inverse kinematics method on a polyethylene target. The experimental excitation function was analyzed using R-matrix calculations. Significantly improved values for the level widths of the four low-lying states in {sup 16}F are reported. Good agreement with the theoretical spectroscopic factors is also obtained.
  • The low-lying states of Ge{sub 2} and Ge{sup {minus}}{sub 2} are probed using negative ion zero electron kinetic energy (ZEKE) spectroscopy. The ZEKE spectrum of Ge{sup {minus}}{sub 2} yields an electron affinity of 2.035{plus_minus}0.001 eV for Ge{sub 2}, as well as term energies and vibrational frequencies for the low-lying states of Ge{sup {minus}}{sub 2} and Ge{sub 2}. Specifically, we observe transitions originating from the anion {sup 2}{Pi}{sub {ital u}}(3/2) ground state and {sup 3}{Sigma}{sup +}{sub {ital g}} excited state ({ital T}{sub {ital e}}=279{plus_minus}10 cm{sup {minus}1}) to several triplet and singlet states of Ge{sub 2}. Term values and vibrational frequencies aremore » determined for the Ge{sub 2}{sup 3}{Sigma}{sup +}{sub {ital g}} ground state, the low-lying {sup 3}{Pi}{sub {ital u}} excited state ({ital T}{sub {ital e}}=337 cm{sup {minus}1} for the 2{sub {ital u}} spin--orbit component), and the somewhat higher lying {sup 1}{Delta}{sub {ital g}}, {sup 3}{Sigma}{sup +}{sub {ital g}}, and {sup 1}{Pi}{sub {ital u}} states. We also determine the zero-field splitting for the {ital X}0{sup +}{sub {ital g}} and 1{sub {ital g}} components of the {sup 3}{Sigma}{sup +}{sub {ital g}} state and the splittings between the 2{sub {ital u}}, 1{sub {ital u}}, and 0{sup {plus_minus}}{sub {ital u}} spin--orbit components of the {sup 3}{Pi}{sub {ital u}} state. Detailed comparisons are made with Si{sub 2} and Si{sup {minus}}{sub 2}.« less
  • In stars, four hydrogen nuclei are converted into a helium nucleus by two competing nuclear fusion processes: the proton - proton chain (p-p) and the carbon - nitrogen - oxygen (CNO) cycle. At temperatures higher than 2x107 K, the CNO cycle dominates the energy production. In particular, its rate is determined by the slowest reaction: 14N(p,{gamma})15O. Direct measurement in a laboratory at the surface of the Earth is hampered by the background due to the cosmic rays. Here we report on an experiment performed with the LUNA (Laboratory for Underground Nuclear Astrophysics) accelerator placed deep underground in the INFN Granmore » Sasso laboratory (Italy). Thanks to the cosmic ray suppression provided by the mountain shield, we could measure the 14N(p,{gamma})15O cross section for the first time directly at energies corresponding to stellar temperatures and with unpreceedent accuracy. In particular we used a large solid angle BGO detector with a differentially pumped windowless gas target. The lowest measured energy is 70.1 keV. Our results have important consequences for the formation of carbon stars, for an independent lower limit on the age of the universe, and for solar neutrino flux.« less