90 research outputs found

    Analytical models and system topologies for remote multispectral data acquisition and classification

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    Simple analytical models are presented of the radiometric and statistical processes that are involved in multispectral data acquisition and classification. Also presented are basic system topologies which combine remote sensing with data classification. These models and topologies offer a preliminary but systematic step towards the use of computer simulations to analyze remote multispectral data acquisition and classification systems

    Viewgraph preparation made easier

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    Rolls of color-reversal film permit exposure of over 200 viewgraphs on one film loading. Time is saved in film development as roll film lends itself readily to automatic processing

    Development of the (d,n) proton-transfer reaction in inverse kinematics for structure studies

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    Transfer reactions have provided exciting opportunities to study the structure of exotic nuclei and are often used to inform studies relating to nucleosynthesis and applications. In order to benefit from these reactions and their application to rare ion beams (RIBs) it is necessary to develop the tools and techniques to perform and analyze the data from reactions performed in inverse kinematics, that is with targets of light nuclei and heavier beams. We are continuing to expand the transfer reaction toolbox in preparation for the next generation of facilities, such as the Facility for Rare Ion Beams (FRIB), which is scheduled for completion in 2022. An important step in this process is to perform the (d,n) reaction in inverse kinematics, with analyses that include Q-value spectra and differential cross sections. In this way, proton-transfer reactions can be placed on the same level as the more commonly used neutron-transfer reactions, such as (d,p), (9Be,8Be), and (13C,12C). Here we present an overview of the techniques used in (d,p) and (d,n), and some recent data from (d,n) reactions in inverse kinematics using stable beams of 12C and 16O.Comment: 9 pages, 4 figures, presented at the XXXV Mazurian Lakes Conference on Physics, Piaski, Polan

    Key 19^{19}Ne states identified affecting Ī³\gamma-ray emission from 18^{18}F in novae

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    Detection of nuclear-decay Ī³\gamma rays provides a sensitive thermometer of nova nucleosynthesis. The most intense Ī³\gamma-ray flux is thought to be annihilation radiation from the Ī²+\beta^+ decay of 18^{18}F, which is destroyed prior to decay by the 18^{18}F(pp,Ī±\alpha)15^{15}O reaction. Estimates of 18^{18}F production had been uncertain, however, because key near-threshold levels in the compound nucleus, 19^{19}Ne, had yet to be identified. This Letter reports the first measurement of the 19^{19}F(3^{3}He,tĪ³t\gamma)19^{19}Ne reaction, in which the placement of two long-sought 3/2+^+ levels is suggested via triton-Ī³\gamma-Ī³\gamma coincidences. The precise determination of their resonance energies reduces the upper limit of the rate by a factor of 1.5āˆ’171.5-17 at nova temperatures and reduces the average uncertainty on the nova detection probability by a factor of 2.1.Comment: 6 pages, 4 figure

    New Ī³\gamma-ray Transitions Observed in 19^{19}Ne with Implications for the 15^{15}O(Ī±\alpha,Ī³\gamma)19^{19}Ne Reaction Rate

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    The 15^{15}O(Ī±\alpha,Ī³\gamma)19^{19}Ne reaction is responsible for breakout from the hot CNO cycle in Type I x-ray bursts. Understanding the properties of resonances between Ex=4E_x = 4 and 5 MeV in 19^{19}Ne is crucial in the calculation of this reaction rate. The spins and parities of these states are well known, with the exception of the 4.14- and 4.20-MeV states, which have adopted spin-parities of 9/2āˆ’^- and 7/2āˆ’^-, respectively. Gamma-ray transitions from these states were studied using triton-Ī³\gamma-Ī³\gamma coincidences from the 19^{19}F(3^{3}He,tĪ³t\gamma)19^{19}Ne reaction measured with GODDESS (Gammasphere ORRUBA Dual Detectors for Experimental Structure Studies) at Argonne National Laboratory. The observed transitions from the 4.14- and 4.20-MeV states provide strong evidence that the JĻ€J^\pi values are actually 7/2āˆ’^- and 9/2āˆ’^-, respectively. These assignments are consistent with the values in the 19^{19}F mirror nucleus and in contrast to previously accepted assignments

    Using \u3csup\u3e19\u3c/sup\u3eF(\u3csup\u3e3\u3c/sup\u3eHe, t)\u3csup\u3e19\u3c/sup\u3eNe\u3csup\u3eāˆ—\u3c/sup\u3e(Ī³) to study astrophysically important levels near the \u3csup\u3e18\u3c/sup\u3eF+ p threshold

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    A direct test of nova explosion models comes from the observation of Ī³ rays created in the decay of radioactive isotopes produced in the nova. One such isotope, 18F, is believed to be the main source of observable Ī³ rays at and below 511 keV. The main destruction mechanism of 18F is thought to be the 18F(p,Ī±)15O reaction, and uncertainties in the reaction rate arise from uncertainties in the energies, spins, and parities of the nuclear levels in 19Ne above the 18F+p threshold. To measure the properties of these levels, the 19F(3He,t)19Ne-(Ī³) reaction was studied at Argonne National Laboratory and the Nuclear Science Laboratory at the University of Notre Dame

    Direct Reaction Measurements Using GODDESS

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    GODDESS is a coupling of the charged-particle detection system ORRUBA to the gamma-ray detector array Gammasphere. This coupling has been developed in order to facilitate the high-resolution measurement of direct reactions in normal and inverse kinematics with stable and radioactive beams. GODDESS has been commissioned using a beam of 134Xe at 10 MeV/A, in a campaign of stable beam measurements. The measurement demonstrates the capabilities of GODDESS under radioactive beam conditions, and provides the first data on the single-neutron states in 135Xe, including previously unobserved states based on the orbitals above the N=82 shell closure

    Structure Studies of 13Be^{13}\text{Be} from the 12^{12}Be(d,p) reaction in inverse kinematics on a solid deuteron target

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    The low-lying structure of 13^{13}Be has remained an enigma for decades. Despite numerous experimental and theoretical studies, large inconsistencies remain. Being both unbound, and one neutron away from 14^{14}Be, the heaviest bound beryllium nucleus, 13^{13}Be is difficult to study through simple reactions with weak radioactive ion beams or more complex reactions with stable-ion beams. Here, we present the results of a study using the 12^{12}Be(d,p)13^{13}Be reaction in inverse kinematics using a 9.5~MeV per nucleon 12^{12}Be beam from the ISAC-II facility. The solid deuteron target of IRIS was used to achieve an increased areal thickness compared to conventional deuterated polyethylene targets. The Q-value spectrum below -4.4~MeV was analyzed using a Bayesian method with GEANT4 simulations. A three-point angular distribution with the same Q-value gate was fit with a mixture of ss- and pp-wave, ss- and dd-wave, or pure pp-wave transfer. The Q-value spectrum was also compared with GEANT simulations obtained using the energies and widths of states reported in four previous works. It was found that our results are incompatible with works that revealed a wide 5/2+5/2^+ resonance but shows better agreement with ones that reported a narrower width.Comment: 10 pages, 5 figure
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