Bulletin of the American Physical Society
2011 Fall Meeting of the APS Division of Nuclear Physics
Volume 56, Number 12
Wednesday–Saturday, October 26–29, 2011; East Lansing, Michigan
Session FB: Mini-Symposium on Experimental Advances in Transfer Reactions III |
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Chair: Jolie Cizewski, Rutgers University Room: Auditorium |
Thursday, October 27, 2011 4:00PM - 4:12PM |
FB.00001: The (7Be,3He) Reaction: A New Tool for Alpha Spectroscopy F.D. Becchetti, H. Amro, Hao Jiang, A.N. Villano, M. Ojaruega, J.J. Kolata, A. Roberts Recent experiments done at the UM-UND low-energy RNB facility \textit{TwinSol} have shown that the (7Be,3He) reaction selectively populates alpha-cluster states (in the case studied,16O) with relatively large cross sections [1]. As will be discussed, this reaction has a number of advantages over both (6Li,d) and (7Li,t) as an alpha-transfer reaction and in particular this reaction for various reasons is not a direct analog of (7Li,t). Thus it can be considered to be a new tool (among few available) for identifying alpha-cluster states in nuclei. Further experiments are planned both at the \textit{TwinSol} facility as well as the new ReA facility at MSU. To facilitate experiments at UND, a new large (ca.1 m dia.) chamber has been built to accommodate large area position-sensitive detectors and improved time-of-flight. Also, a new technique for making single-sided enriched oxygen targets suitable for low-energy (7Be,3He) studies has been developed and will be reported elsewhere (M. Febrraro \textit{et al.}, this conference).\\[4pt] [1] ``$^{7}$Be-induced $\alpha$-transfer reaction on $^{12}$C,'' H. Amro, \textit{et al.}, Eur. Phys. J. Special Topics \textbf{150,} 1-7 (2007). [Preview Abstract] |
Thursday, October 27, 2011 4:12PM - 4:24PM |
FB.00002: Experimental techniques to use the $(d,n)$ reaction for spectroscopy of low-lying proton-resonances Ingo Wiedenhoever, Alexander Rojas, Lagy T. Baby, Jessica Baker, Sean Kuvin, Patrick Peplowski, Daniel Santiago-Gonzalez, Georgios Perdikakis, Dennis L. Gay Studies of rp-process nucleosynthesis in stellar explosions show that establishing the lowest $l=0$ and $l=1$ resonances is the most important step to determine reaction rates in the astrophysical $rp$--process path. At the {\sc resolut} facility, we have used the $(d,n)$ reaction to populate the lowest $p$-- resonances in $^{26}$Si, and demonstrated the usefulness of this approach to populate the resonances of astrophysical interest[1]. In order to establisg the $(d,n)$ reaction as a standard technique for the spectroscopy of astrophysical resonances, we have developed a compact setup of low-energy Neutron-detectors, {\sc resoneut} and tested it with the stable beam reaction $\mathrm{^{12}C(d,n)^{13}N}$ in inverse kinematics. Performance data from this test-experiment and future plans for this setup will be presented. \\[4pt] [1] P.N. Peplowski {\it et al.} Phys.Rev.{\bf C 79}, 032801 (2009) [Preview Abstract] |
Thursday, October 27, 2011 4:24PM - 4:36PM |
FB.00003: First use of HELIOS at forward laboratory angles B.P. Kay, M. Alcorta, B.B. Back, J.A. Clark, C.R. Hoffman, K.E. Rehm, J.P. Schiffer, S. Zhu, C.M. Deibel The HELIOS spectrometer eliminates the problem of kinematic compression when performing transfer reactions in inverse kinematics, typically resulting in a factor of $\sim$3 improvement in excitation-energy resolution over conventional approaches. To date the instrument has been used primarily for ($d$,$p$) reaction studies with both stable and radioactive ion beams, where the outgoing protons are detected at backwards laboratory angles. Here we report on the first use of HELIOS with negative- Q-value reactions; the ($d$,$t$) and ($d$,$^3$He) reactions induced by a 14-MeV/u $^{28}$Si beam on a CD$_2$ target. For these reactions, outgoing tritons and $^3$He ions are detected at forward laboratory angles along with a range of unwanted reactions products. In HELIOS, particle identification by means of the cyclotron period of the outgoing ion allows unique selection of the low-energy branch of $^3$He or tritons, separating them from the dominant background of protons and alpha particles that arise from fusion-evaporation of the beam with $^{12}$C. This work was supported by the US Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357 and Grant No. DE-FG-2-04ER41320, and NSF Grant No. PHY-08022648, and the UK Science and Technology Facilities Council. [Preview Abstract] |
Thursday, October 27, 2011 4:36PM - 4:48PM |
FB.00004: Low-threshold neutron detection for proton-transfer reactions with VANDLE William Peters, R. Grzywacz, M. Madurga, S. Paulauskas, J.A. Cizewski, M.E. Howard, P.D. O'Malley, B. Manning, E. Merino, T.N. Massey, C. Brune, F. Sarazin, S. Ilyuskin, D. Walter, J. Blackmon, D.W. Bardayan, I. Spassova, C. Matei Proton-transfer studies with radioactive beams are a useful tool for constraining astrophysical proton-capture rates and probing the single-particle structure of exotic nuclei. Measurements from (d,n) reactions on radioactive beams require an efficient large- area neutron detector array. The Versatile Array of Neutron Detectors at Low Energy (VANDLE) is being developed at ORNL for both (d,n) and beta-delayed neutron spectroscopy measurements. Digital electronics and optimized materials make VANDLE sensitive to neutron--proton scattering for neutrons above 100~keV, and also to elastically scattered carbon from neutrons above 1~MeV. This carbon sensitivity supplements the detection efficiency at those energies. Measured efficiencies from an $^{27}$Al(d,n) study at Ohio University and from a $^{252}$Cf source will be presented, along with plans and simulated responses for (d,n) measurements of astrophysicaly important proton-capture reactions. [Preview Abstract] |
Thursday, October 27, 2011 4:48PM - 5:00PM |
FB.00005: Coupling the ORRUBA and Gammasphere Arrays Steven Hardy, A. Adekola, J.A. Cizewski, M.E. Howard, P.D. O'Malley, B. Manning, D.W. Bardayan, S.D. Pain, C.J. Lister, D. Seweryniak, J.C. Blackmon, M. Matos, K.A. Chipps, K.L. Jones, R.L. Kozub, W.A. Peters The coincident detection of charged particles and gamma rays with high resolution facilitates the performance of numerous nuclear physics measurements. These include the study of the fragmentation of single-particle strengths close to shell closures, surrogate measurements to inform neutron capture, heavy-ion transfer reactions and inelastic scattering measurements to probe collective states. The large internal geometry of Gammasphere is ideally suited to coupling to a large solid-angle silicon detector array, maximizing gamma ray efficiency without compromising charged particle angular resolution. The upcoming coupling of the ORRUBA and Gammasphere arrays for the coincident measurement of charged particles and gamma rays with high-efficiency and high-resolution will be discussed. [Preview Abstract] |
Thursday, October 27, 2011 5:00PM - 5:12PM |
FB.00006: Deuterated Liquid Scintillators: A New Tool for Neutrons without ToF for RNB Reaction Studies Mitaire Ojaruega, Fred Becchetti, J.J. Kolata, Amy Roberts, Ramon Torres-Isea, Michael Febbraro An array of 6 large deuterated neutron detectors ((100mm x 150mm) has been developed at the University of Michigan. These detectors will make it possible to carry out RNB measurements with neutrons as the outgoing particle. The ability of this detector to obtain neutron energy spectra from nuclear reactions without the use of time of flight (ToF) has been verified and will be utilized. Typical data collected with these detectors showing optimized pulse-shape-discrimination, some using digital pulse analysis from this detector will be presented. This work is supported by the U.S. National Science Foundation under Contracts PHY-0652591, CMMI 0936649, PHY-0969456 and PHY-0758100. [Preview Abstract] |
Thursday, October 27, 2011 5:12PM - 5:24PM |
FB.00007: Prototype AT-TPC: a new active target time projection chamber for low-energy reactions D. Suzuki, D. Bazin, W. Mittig, M. Ford, W.G. Lynch, A. Fritsch, E. Galyaev, J.J. Kolata, J. Browne, B. Bucher, X. Fang, A. Howard, A.L. Roberts, X.D. Tang, F.D. Becchetti , M. Febbraro, M. Ojaruega, D. Ben Ali An active target time projection chamber (AT-TPC) is being developed at the National Superconducting Cyclotron Laboratory. The detector will be coupled to the forthcoming ReA3 accelerator complex, providing a powerful tool for reaction studies with low-energy radioactive beams. The Prototype AT-TPC, a half scale version of the future AT-TPC, has recently been completed. The first in-beam experiment was performed at the University of Notre Dame in April. The elastic and inelastic alpha scattering on radioactive $^{6}$He beams were measured at low energy to study the neutron transfer or resonant processes. The $^{6}$He beam at 14 MeV was produced by the Twinsol device, and directed to the Prototype AT-TPC operated with He:CO$_{2}$ gas mixtures. The design and the performances of the detector, and the results from the Notre Dame experiment will be presented. [Preview Abstract] |
Thursday, October 27, 2011 5:24PM - 5:36PM |
FB.00008: A Gas Jet Target for Radioactive Ion Beam Experiments K.A. Chipps With the development of new radioactive ion beam (RIB) facilities such as FRIB, which will push further away from stability, the need for improved RIB targets is more crucial than ever. Important scattering, transfer and capture reaction measurements of rare, exotic, and unstable nuclei on hydrogen and helium require targets that are dense ($\sim1\times10^{19} nuclei/cm^{2}$), highly localized, and pure. Conventional targets suffer too many drawbacks to allow for such measurements. Targets must also accommodate the use of novel detector arrays. To this end, a collaboration led by the Colorado School of Mines (CSM) is designing, building and testing a supersonic gas jet target for use at existing and future RIB facilities. The gas jet target allows for a high density and purity of target nuclei (such as $^{3}$He) within a highly confined region, without the use of windows or backing materials, and will also enable the use of state-of-the-art detection systems. Motivation, specifications and status of the CSM gas jet target system will be discussed. [Preview Abstract] |
Thursday, October 27, 2011 5:36PM - 5:48PM |
FB.00009: The $^{12}$C($^{6}$He,$^{4}$He) transfer reaction at 5 MeV per nucleon at the ISAC-II TRIUMF facility Duane Smalley, Fred Sarazin, Ulrike Hager The $^{12}$C($^{6}$He,$^{4}$He)$^{14}$C transfer reaction was studied using the ${\bf S}$ilicon ${\bf H}$ighly-segmented ${\bf A}$rray for ${\bf R}$eactions and ${\bf C}$oulex (SHARC), a compact charged particle silicon detector array, and the ${\bf T}$RIUMF-${\bf I}$SAC ${\bf G}$amma-${\bf r}$ay ${\bf E}$scape ${\bf S}$uppressed ${\bf S}$pectrometer (TIGRESS), a high-efficiency $\gamma$-ray detector, at the TRIUMF/ISAC-II facility. The goal of the experiment is to compare the two-neutron transfer cross sections using ($^{6}$He,$^{4}$He) to the more traditional (t,p) on $^{12}$C. The study requires good angular resolution coupled with particle identification, both of which are provided by SHARC with its 10,000 Si pixels instrumented by over 800 DAQ channels including a number of $\Delta$E-E telescopes. Since the identification of the individual $^{14}$C excited states requires coincident detection of $\gamma$ events, the HPGe BGO-suppressed TGIRESS detectors contribute $\gamma$ detection over a large solid angle. The combination of the two detector arrays allows accurate reconstruction of reaction kinematics, including Doppler correction. Preliminary results of the experiment will be presented. [Preview Abstract] |
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