147 research outputs found
TriSol: a major upgrade of the TwinSol RNB facility
We report here on the recent upgrade of the TwinSol radioactive nuclear beam
(RNB) facility at the University of Notre Dame. The new TriSol system includes
a magnetic dipole to provide a second beamline and a third solenoid which acts
to reduce the size of the radioactive beam on target.Comment: submitted to Nuclear Instruments and Methods
Unbound states of 32Cl and the 31S(p,\gamma)32Cl reaction rate
The 31S(p,\gamma)32Cl reaction is expected to provide the dominant break-out
path from the SiP cycle in novae and is important for understanding enrichments
of sulfur observed in some nova ejecta. We studied the 32S(3He,t)32Cl
charge-exchange reaction to determine properties of proton-unbound levels in
32Cl that have previously contributed significant uncertainties to the
31S(p,\gamma)32Cl reaction rate. Measured triton magnetic rigidities were used
to determine excitation energies in 32Cl. Proton-branching ratios were obtained
by detecting decay protons from unbound 32Cl states in coincidence with
tritons. An improved 31S(p,\gamma)32Cl reaction rate was calculated including
robust statistical and systematic uncertainties
Mg(, )Na reaction study for spectroscopy of Na
The Mg(, )Na reaction was measured at the Holifield
Radioactive Ion Beam Facility at Oak Ridge National Laboratory in order to
better constrain spins and parities of energy levels in Na for the
astrophysically important F()Ne reaction rate
calculation. 31 MeV proton beams from the 25-MV tandem accelerator and enriched
Mg solid targets were used. Recoiling He particles from the
Mg(, )Na reaction were detected by a highly segmented
silicon detector array which measured the yields of He 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 Na and Distorted Wave Born Approximation (DWBA) calculations were
compared to verify and extract angular momentum transfer.Comment: 11 pages, 6 figures, proceedings of the 18th International Conference
on Accelerators and Beam Utilization (ICABU2014
Experimental study of the nature of the 1− and 2− excited state
The nature of the 1− and 2− excited states in 10Be is studied using the 11Be(p, d) transfer reaction in
inverse kinematics at 10A MeV at TRIUMF ISAC-II, in particular to assess whether either of them can be
considered as an excited halo state. The angular distributions for both states are extracted using deuteron-γ
coincidences and analyzed using a transfer model taking into account one-step and two-step processes. A good
fit of the angular distributions is obtained considering only the one-step process, whereby an inner p3/2 neutron
of 11Be is removed, leaving the halo neutron intact. Higher-order processes however cannot be rejected. The
small spectroscopic factors extracted suggest that the structure of both states is not uniquely halo-like, but
rather display a more complex configuration mixing cluster and halo structures. Further insights are limited, as
this experiment specifically probed the halo-like (but not cluster-like) 11Be(1/2+) ⊗ (ν p3/2 )
−1 configuration in
both states.U.S. Department of Energy (DOE): DE-FG03-93ER40789 (Colorado School of Mines), DE-FG02-96ER40978 (Louisiana State), DE-SC0021422 (Michigan State), DE-AC05-00OR22725 (Oak Ridge National Laboratory)The National Nuclear Security Administration a través de los acuerdos de cooperación del DOE de EE. UU.(NNSA) DE-FG52-08NA28552The National Science Foundation PHY-1811815 (Michigan State)Ministerio español de Ciencia e Innovación y fondos FEDER. RTI2018-098117-B-C21 y PGC2018-096994-BC21Agencia Española de Investigación (AEI). PID2019-104714GB-C2
A New 17F(p,gamma)18Ne Reaction Rate and Its Implications for Nova Nucleosynthesis
Proton capture by 17F plays an important role in the synthesis of nuclei in
nova explosions. A revised rate for this reaction, based on a measurement of
the 1H(17F,p)17F excitation function using a radioactive 17F beam at ORNL's
Holifield Radioactive Ion Beam Facility, is used to calculate the
nucleosynthesis in nova outbursts on the surfaces of 1.25 and 1.35 solar mass
ONeMg white dwarfs and a 1.00 solar mass CO white dwarf. We find that the new
17F(p,gamma)18Ne reaction rate changes the abundances of some nuclides (e.g.,
17O) synthesized in the hottest zones of an explosion on a 1.35 solar mass
white dwarf by more than a factor of 10,000 compared to calculations using some
previous estimates for this reaction rate, and by more than a factor of 3 when
the entire exploding envelope is considered. In a 1.25 solar mass white dwarf
nova explosion, this new rate changes the abundances of some nuclides
synthesized in the hottest zones by more than a factor of 600, and by more than
a factor of 2 when the entire exploding envelope is considered. Calculations
for the 1.00 solar mass white dwarf nova show that this new rate changes the
abundance of 18Ne by 21%, but has negligible effect on all other nuclides.
Comparison of model predictions with observations is also discussed.Comment: 20 pages, 6 figures, accepted for publication in Ap
New Features in the Computational Infrastructure for Nuclear Astrophysics
A Computational Infrastructure for Nuclear Astrophysics has been developed to streamline the inclusion of the latest nuclear physics data in astrophysics simulations. The infrastructure consists of a platform-independent suite of computer codes that are freely available online at http://nucastrodata.org. The newest features of, and future plans for, this software suite are given. © Copyright owned by the author(s)
Obtaining high resolution excitation functions with an active thick-target approach and validating them with mirror nuclei
Measurement of fusion excitation functions for stable nuclei has largely been
restricted to nuclei with significant natural abundance. Typically, to
investigate neighboring nuclei with low natural abundance has required
obtaining isotopically enriched material. This restriction often limits the
ability to perform such measurements. We report the measurement of a high
quality fusion excitation function for a O beam produced from unenriched
material with 0.038\% natural abundance. The measurement is enabled by using an
active thick-target approach and the accuracy of the result is validated using
its mirror nucleus F and resonances. The result provides important
information about the average fusion cross-section for the oxygen isotopic
chain as a function of neutron excess.Comment: 4 pages, 4 figure
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