The properties of the 2(1)(+) and 2(2)(+) excited states in C-14 were studied in an experiment conducted at the Argonne National Laboratory. A Be-9(Li-6, p gamma) fusion-evaporation reaction and the GRETINA-ORRUBA setup were employed to populate states of C-14 and detect gamma-particle coincidence events. The precise determination of the 2(1)(+) level energy, complemented by the estimation of the gamma-ray branch of the 2(2)(+) near-threshold state, will serve as a benchmark to test the Shell Model Embedded in the Continuum calculations.

The availability of high-intensity, heavy-ion beams coupled to sensitive, large solid-angleacceptance spectrometers has enabled a detailed examination of the fission fragments produced in induced-fission reactions. The abrasion-fission process involves the formation of projectile-like prefragments in violent nuclear collisions at relative energies in excess of 100 MeV/u. At intermediate energies below this threshold, experiments suggest a change in the prefragment kinematic qualities. Information regarding the influence of this transitional phase upon the evolution of nuclei approaching the point of scission is scarce. In this article, data are presented for over 200 nuclei from nickel to palladium produced in abrasion-fission reactions of a 80 MeV/u 238U beam. Cross sections were obtained following yield measurements performed for the principal charge states of the identified fission fragments and a detailed analysis of the ion transmission. A full kinematic analysis of the fission fragments has been performed using the LISE++ software package, where the trajectory of an ion passing through a spectrometer can be reconstructed based upon measurements at the focal plane. The results obtained at the S800 spectrograph are compared with predictions obtained with a three-fission progenitor (3EER) model. Systematic studies of fission-fragment properties continue to provide a valuable experimental benchmark for theoretical efforts directed toward describing this complex decay channel, that is important in the context of planning experiments to explore the neutron-rich region of the nuclear chart at rare-isotope beam facilities.

The observation of γ rays from the decay of 44Ti in the remnants of core-collapse supernovae (CCSNe) provides crucial information regarding the nucleosynthesis occurring in these events, as 44Ti production is sensitive to CCSNe conditions. The final abundance of 44Ti is also sensitive to specific nuclear input parameters, one of which is the 57Ni(p,γ)58Cu reaction rate. A precise rate for 57Ni(p,γ)58Cu is thus critical if 44Ti production is to be an effective probe into CCSNe. To experimentally constrain the 57Ni(p,γ)58Cu rate, the structure properties of 58Cu were measured via the 58Ni(3He,t)58Cu*(γ) reaction using GODDESS (GRETINA ORRUBA Dual Detectors for Experimental Structure Studies) at Argonne National Laboratory’s ATLAS facility. Details of the experiment, ongoing analysis, and plans are presented.

We report on the Facility for Rare Isotope Beams (FRIB) Theory Alliance topical program "Nuclear Isomers in the Era of FRIB". We outline the many ways isomers influence and contribute to nuclear science and technology, especially in the four FRIB pillars: properties of rare isotopes, nuclear astrophysics, fundamental symmetries, and applications for the nation and society. We conclude with a resolution stating our recommendation that the nuclear physics community actively pursue isomer research. A white paper is forthcoming.

Background: The anomalous Ne-22 abundance measured in certain presolar graphite grains is thought to arise from the decay of Na-22 that was synthesized at high temperatures in core-collapse supernovas. To better interpret this abundance anomaly, the primary destruction mechanism of Na-22, the Na-22(p, gamma)Mg-23 reaction, must be better understood. Purpose: Determine proton branching ratios of several Mg-23 excited states that play a role in the hightemperature Na-22(p, gamma)Mg-23 reaction rate. Methods: Particle decays of Mg-23 excited states populated with the previously reported Mg-24(p, d)Mg-23 transfer reaction measurement [Kwag et al., Fur. Phys. J. A 56. 108 (2020)] were analyzed to extract proton branching ratios. The reaction was studied using a 31-MeV proton beam from the Holifield Radioactive Ion Beam Facility of Oak Ridge National Laboratory and Mg-24 solid targets. Results: Proton branching ratios of several Mg-23 excited states in the energy range E-x = 8.044-9.642 MeV were experimentally determined for the first time for the p0 and p1' (p1 + p2 + p3) decay channels. Conclusions: These new branching ratios for Mg-23 levels can provide an experimental foundation for an improved high-temperature rate of the Na-22(p, gamma)Mg-23 reaction needed to understand production of anomalously high Ne-22 abundance in core-collapse supernovas.

To determine the safety of using argon as a deuteron beam stopping material, the  40Ar(d,p)41Ar cross section was measured at average deuteron energies of 3.6 MeV, 5.5 MeV, and 7.0 MeV using an activation method. A 16-MeV deuteron beam produced by Lawrence Berkeley National Laboratory's 88-Inch Cyclotron was degraded to each energy by nickel foils and the front wall of an aluminum gas chamber. The reduced-energy deuterons were used to activate a sample of natAr gas. After each irradiation, the gas chamber's  41Ar activation was measured with a high-purity germanium detector. The cross sections measured were larger than a previous measurement by ∼40%.

K.L. Jones, ∗ A. Bey, 2 S. Burcher, J.M. Allmond, 3 A. Galindo-Uribarri, 1 D.C. Radford, S. Ahn, 2 A. Ayres, D.W. Bardayan, 4 J. A. Cizewski, R.F. Garcia Ruiz, 3, 6, † M.E. Howard, R.L. Kozub, J.F. Liang, B. Manning, M. Matos, C.D. Nesaraja, P.D. O’Malley, 5 E. Padilla-Rodal, S.D. Pain, S.T. Pittman, 8 A. Ratkiewicz, K.T. Schmitt, M.S. Smith, D.W. Stracener, and R.L. Varner Department of Physics and Astronomy, 401 Nielsen Physics Building, 1408 Circle Drive, University of Tennessee, Knoxville, TN 37996, USA Joint Institute for Nuclear Physics and Applications, Oak Ridge National Laboratory, Oak Ridge TN 37831, USA Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA Department of Physics, University of Notre Dame, Notre Dame, IN 46556, USA Department of Physics and Astronomy, Rutgers University, New Brunswick, NJ 08903, USA Instituut voor Kernen Stralingsfysica, KU Leuven, B-3001, Leuven, Belgium Department of Physics, Tennessee Technological University, Cookeville, TN 38505, USA Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803, USA Instituto do Ciencias Nucleares, UNAM, AP 70-543, 04510, Mexico (Dated: January 25, 2022)

The beta decay of Ag-125m,Ag-125 into levels in Cd-125 was investigated at the Holifield Radioactive Ion Beam Facility (HRIBF). Uranium-238 targets were bombarded with 50-MeV protons with an intensity of 15 mu A, and the induced fission products were mass separated and deposited on a moving tape in the center of the VANDLE array consisting of gamma detectors and plastic scintillators. A partial decay scheme has been assigned for both beta decay of the (9/2(+)) ground state of Ag-125 and its low-lying (1/2(-)) isomer, with the energy of the low-lying (11/2-) isomeric state in Cd-125 assigned as 188.5 keV. In addition, beta-delayed neutron emission probabilities were also determined to be 1.2(2)% for the (9/2(+)) Ag-125 ground state and 4.6(10)% for the (1/2(-)) isomer, which are substantially lower than the previously reported value.

Decay protons from excited states in $^{21}\mathrm{Na}$ populated through a previously reported $^{24}\mathrm{Mg}(p,\ensuremath{\alpha})^{21}\mathrm{Na}$ transfer reaction [Cha et al., Phys. Rev. C 96, 025810 (2017)] were analyzed to extract the proton branching ratios of the energy levels. By utilizing 31-MeV proton beams from the Holifield Radioactive Ion Beam Facility of Oak Ridge National Laboratory and isotopically enriched $^{24}\mathrm{Mg}$ solid targets, the decay protons were detected in coincidence with $\ensuremath{\alpha}$ particles from the $(p,\ensuremath{\alpha})$ reaction using a silicon strip detector array. Proton decay branching ratios of several $^{21}\mathrm{Na}$ levels were deduced for the $p0$ and $p1$ decay channels to the ground and first excited states in $^{20}\mathrm{Ne}$, respectively.

Neutron capture reactions are responsible for the synthesis of almost all of the elements heavier than iron through s-process and r-process nucleosynthesis. Uncertainties in (n,γ) rates on neutron-rich nuclei can have significant impact on the predictions of observed r-process abundances for different astrophysical scenarios. The (d,pγ) reaction has recently been demonstrated to be a valid surrogate for (n,γ). This reaction has been measured in inverse kinematics with Gammasphere ORRUBA: Dual Detectors for Experimental Structure Studies (GODDESS) where the Gammasphere array of Compton-suppressed HPGe detectors is coupled to the Oak Ridge Rutgers University Barrel Array (ORRUBA) of position-sensitive silicon-strip detectors. Preliminary results from the (d,pγ) measurement with 134Xe beams are reported.

The $\ensuremath{\beta}$ decay of $^{125m,125}\mathrm{Ag}$ into levels in $^{125}\mathrm{Cd}$ was investigated at the Holifield Radioactive Ion Beam Facility (HRIBF). Uranium-238 targets were bombarded with 50-MeV protons with an intensity of $15\phantom{\rule{4pt}{0ex}}\ensuremath{\mu}$A, and the induced fission products were mass separated and deposited on a moving tape in the center of the VANDLE array consisting of $\ensuremath{\gamma}$ detectors and plastic scintillators. A partial decay scheme has been assigned for both $\ensuremath{\beta}$ decay of the (9/${2}^{+}$) ground state of $^{125}\mathrm{Ag}$ and its low-lying (1/${2}^{\ensuremath{-}}$) isomer, with the energy of the low-lying (11/${2}^{\ensuremath{-}}$) isomeric state in $^{125}\mathrm{Cd}$ assigned as 188.5 keV. In addition, $\ensuremath{\beta}$-delayed neutron emission probabilities were also determined to be 1.2(2)% for the (9/${2}^{+}$) $^{125}\mathrm{Ag}$ ground state and 4.6(10)% for the (1/${2}^{\ensuremath{-}}$) isomer, which are substantially lower than the previously reported value.

The 24Mg(p,α)21 Na 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.

Lawrence Livermore National Laboratory (LLNL) is near-completion of a quasi-monoenergetic neutron source for fastneutron imaging and computed tomography (CT). The source is expected to produce 10-MeV neutrons with an on-axis flux of ~1011 per second per steradian through a collimated aperture with a ~7-degree opening angle. The application for this source is imaging and CT of low-Z materials heavily shielded by high-Z materials. Fast-neutron imaging and CT is a non-destructive technique for very thick objects. We have radiographed a variety of objects using various sources of fast neutrons. We will discuss our CT reconstruction methods and results from these measurements. We will also discuss our results as they relate to our expectations of the near-complete neutron source at LLNL.

The $$^{22}\hbox {Na}(p,\gamma )^{23}\hbox {Mg}$$ reaction is responsible for destruction of the long-lived radionuclide $$^{22}\hbox {Na}$$ produced during nova explosions. Since the reaction proceeds through resonances from levels in $$^{23}\hbox {Mg}$$ above the proton threshold at 7.581 MeV, the properties of these levels such as excitation energies, spins, and parities are crucial ingredients to determine the $$^{22}\hbox {Na}(p,\gamma )^{23}\hbox {Mg}$$ reaction rate. Despite recent studies of these levels, their spins are not well constrained in many cases. We have measured the $$^{24}\mathrm{Mg}(p,d)^{23}\hbox {Mg}$$ transfer reaction to determine spectroscopic properties of these levels at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. The spin of the $$E_{x}$$ = 7.788 MeV level in $$^{23}\hbox {Mg}$$ is constrained to be $$J^{\pi }$$ = (3/2$$^+$$, 5/2$$^+$$) through the present work. The astrophysical $$^{22}\hbox {Na}(p,\gamma )^{23}\hbox {Mg}$$ reaction rate at nova temperatures is updated accordingly. Nova nucleosynthesis model calculations using the newly updated $$^{22}\hbox {Na}(p,\gamma )^{23}\hbox {Mg}$$ reaction rate shows that the final weighted abundance of the radionuclide $$^{22}\hbox {Na}$$ is increased by 42% compared to that obtained by using the previous $$^{22}\hbox {Na}(p,\gamma )^{23}\hbox {Mg}$$ reaction rate of Sallaska et al. for a 1.35 $$M_{\odot }$$ ONeMg white dwarf.

Background: Nova explosions synthesize elements up to A similar or equal to 40, and discrepancies exist between calculated and observed abundances of Ar and Ca created in the explosion. The K-38(p, gamma) Ca-39 reaction rate has been shown to be influential on these isotopic abundances at the endpoint of nova nucleosynthesis. The energies of the three most important resonances, corresponding to J(pi) = 5/2(+) excited states in the Ca-39 nucleus above the proton separation threshold, are uncertain and one has been measured with conflicting values [E-r = 679(2) versus E-r = 701(2) keV] in previous experiments. Purpose: Reducing the uncertainties on the resonance energies would allow for a better understanding of the reaction rate. To improve these uncertainties, we searched for gamma rays from the depopulation of the corresponding excited states in Ca-39. Methods: We report a new measurement of these resonance energies via the observation of previously unobserved gamma-ray transitions. These transitions were observed by studying the Ca-40(He-3, alpha gamma) Ca-39 reaction with Gammasphere ORRUBA Dual Detectors for Experimental Structure Studies (GODDESS). The updated resonance energies were then used to calculate the K-38(p, gamma)Ca-39 reaction rate and assess its uncertainties. Results: In total, 23 new transitions were found, including three gamma -ray transitions corresponding to the three J(pi)= 5/2(+) states of astrophysical interest at energies of 6156.2(16), 6268.8(22), and 6470.8(19) keV. These correspond to resonance energies in the K-38(p, gamma)Ca-39 reaction of 386(2), 498(2), and 701(2) keV. Conclusions: Updated K-38(p, gamma) Ca-39 reaction rate calculations show a reduced upper limit at nova temperatures. However, the lower-than-previously-measured energy of the 498-keV resonance and uncertainty in its resonance strength increases the upper limit of the rate close to previous estimates at 0.4 GK.

The $$^{22}\hbox {Na}(p,\gamma )^{23}\hbox {Mg}$$ reaction is responsible for destruction of the long-lived radionuclide $$^{22}\hbox {Na}$$ produced during nova explosions. Since the reaction proceeds through resonances from levels in $$^{23}\hbox {Mg}$$ above the proton threshold at 7.581 MeV, the properties of these levels such as excitation energies, spins, and parities are crucial ingredients to determine the $$^{22}\hbox {Na}(p,\gamma )^{23}\hbox {Mg}$$ reaction rate. Despite recent studies of these levels, their spins are not well constrained in many cases. We have measured the $$^{24}\mathrm{Mg}(p,d)^{23}\hbox {Mg}$$ transfer reaction to determine spectroscopic properties of these levels at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. The spin of the $$E_{x}$$ = 7.788 MeV level in $$^{23}\hbox {Mg}$$ is constrained to be $$J^{\pi }$$ = (3/2$$^+$$, 5/2$$^+$$) through the present work. The astrophysical $$^{22}\hbox {Na}(p,\gamma )^{23}\hbox {Mg}$$ reaction rate at nova temperatures is updated accordingly. Nova nucleosynthesis model calculations using the newly updated $$^{22}\hbox {Na}(p,\gamma )^{23}\hbox {Mg}$$ reaction rate shows that the final weighted abundance of the radionuclide $$^{22}\hbox {Na}$$ is increased by 42% compared to that obtained by using the previous $$^{22}\hbox {Na}(p,\gamma )^{23}\hbox {Mg}$$ reaction rate of Sallaska et al. for a 1.35 $$M_{\odot }$$ ONeMg white dwarf.