Bulletin of the American Physical Society
2016 Fall Meeting of the APS Division of Nuclear Physics
Volume 61, Number 13
Thursday–Sunday, October 13–16, 2016; Vancouver, BC, Canada
Session FE: Nuclear Structure I (A<21) |
Hide Abstracts |
Chair: Mustafa Rajabali, Tennessee Technological University Room: Junior Ballroom D |
Friday, October 14, 2016 4:00PM - 4:12PM |
FE.00001: Precision excited-state lifetime measurements of neutron-rich Li isotopes C. Morse, C.J. Lister, G.L. Wilson, E.A. McCutchan, G. Hackman, M. Bowry, R. Caballero-Folch, L.J. Evitts, A.B. Garnsworthy, J. Henderson, A. Kurkjian, J.P. Measures, M. Moukaddam, P. Ruotsalainen, J. Smallcombe, J.K. Smith, D. Southall, M. Williams, A.J. Mitchell, C.Y. Wu Recent successes with \textit{ab initio} calculations are allowing increasingly subtle nuclear phenomena to be investigated, such as $\Delta$-isobar and meson exchange effects which are necessary to reproduce $M1$ properties of nuclei. In order to guide such explorations, precise experimental data are required to discriminate between various theoretical descriptions. The lithium isotopes, which are dominated by $M1$ spin-flip transitions, provide an ideal testing ground for such studies. We have performed lifetime measurements of the excited states of $^{7,8}$Li, as well as explored the feasibility of such an experiment on $^9$Li, to provide precise data on the $M1$ transition matrix elements in these nuclei. The experiment used the Doppler Shift Attenuation Method to measure the lifetimes at TRIUMF with TIGRESS, with the excited states populated by inverse $(d,p)$ reactions. Preliminary results from the analysis will be presented. [Preview Abstract] |
Friday, October 14, 2016 4:12PM - 4:24PM |
FE.00002: Study of $^{11}$Be on $^9$Be one neutron transfer reactions at TRIUMF ISAC-II Ryan Braid The structure of neutron-rich Beryllium isotopes displays interesting properties arising from the interplay of alpha clustering and valence neutrons, leading in some cases to halo nuclei. In this presentation, preliminary results of the $^{11}$Be on $^{9}$Be reaction at 55 MeV and 30.14 MeV leading to two interesting exit channels will be shown, the first one enabling the study of $^{12}$Be and the second the study of $^{10}$Be. This reaction has advantages over the traditional (d,p) or (d,t) methods, since the reactants are equal in mass they both scatter in a detectable angular range. Additionally, TIGRESS allows precise $\gamma$-tagging for the excited states. Some challenges in analysis include the $^{10}$Be degeneracy, a large $n$ breakup signature, and multiple particle excitation. The data and ongoing analysis will be presented. This work is partially supported by the US Department of Energy through Grant/Contract No. DE-FG03- 93ER40789 (Colorado School of Mines). [Preview Abstract] |
Friday, October 14, 2016 4:24PM - 4:36PM |
FE.00003: Studying 10BE and 11BE Halo States Through The (P,D) Single-Neutron Transfer Reaction Keri Kuhn, Fred Sarazin One-neutron transfer reactions are being used to study single-particle neutron states in nuclei. For one-neutron halo nuclei, such as $^{11}$Be, the (p,d) reaction enables the removal of the halo neutron or of one of the core neutrons. This way, it is possible to simultaneously study the halo wavefunction of the $^{11}$Be ground-state but also a possible excited halo state in $^{10}$Be. The $^{11}$Be(p, d)$^{10}$Be transfer reaction at 10 MeV/nucleon is being investigated at the TRIUMF-ISAC II facility with the Printed Circuit Board Based Charged Particle ((PCB)$^2$) array inside the TRIUMF ISAC Gamma-Ray Escape-Suppressed Spectrometer (TIGRESS). The ground state and first excited state of $^{10}$Be can be directly identified using deuteron identification and kinematics from the charged particle array, while the four excited states in$^{10}$Be around 6 MeV, including the suspected halo state ( 2$^-$ state), are identified using coincident gamma rays from TIGRESS with the identified deuterons. Angular distributions for the $^{10}$Be populated states will be shown along with their FRESCO fits. [Preview Abstract] |
Friday, October 14, 2016 4:36PM - 4:48PM |
FE.00004: Measurements of Gamma Rays from $^7Be$ Inelastic Scattering S.L. Henderson, T. Ahn, J. Allen, D.W. Bardayan, M.A. Caprio, Ch. Constantinou, P. Fasano, B. Frentz, M. Hall, L. Jensen, J.J. Kolata, X. Li, A.E. McCoy, S. Moylan, P. O'Malley, C.S. Re, J. Riggins, A. Simon, R. Torres-Isea, S. Strauss Ab-initio methods have been successful in describing the structure of light nuclei using realistic nucleon-nucleon interactions, but more experimental data is needed in the light unstable nuclei region. No-core configuration interaction calculations have made predictions for the M1 and a lower limit for the E2 electromagnetic transition strengths of the decay of the first excited state of $^7Be$ where the latter has never before been measured. To measure the E2 transition strength, a Coulomb Excitation experiment was performed using TwinSol at the University of Notre Dame. A beam of $^7Be$ ions were scattered off a gold target, and gamma rays from inelastically scattered ions were detected using clover Ge detectors. Preliminary results for the E2 transition strength and its comparison to the no-core configuration interaction approach will be shown. Extensions of this experimental method to other light unstable nuclei will be discussed. [Preview Abstract] |
Friday, October 14, 2016 4:48PM - 5:00PM |
FE.00005: Study of the structure of $^{14}$O using resonant scattering Tan Ahn Theoretical cluster models and recent experimental work have given evidence for prominent cluster structures in the light $Z \neq N$ nucleus $^{14}$C. In $^{14}$C, the presence of additional nucleons are important for the formation of unique cluster structures. In order to extend the search for cluster structures to proton-rich nuclei, we have performed an experiment using $^{10}$C + $\alpha$ resonant scattering to probe levels in $^{14}$O, the isobaric mirror of $^{14}$C. A radioactive beam of $^{10}$C produced with the TwinSol superconducting solenoids was impinged on a He gas target provided by the the Prototype Active-Target Time Projection-Chamber. Charged-particle tracks were recorded to deduce scattering cross sections. Results of the experiment and analysis in terms of $R$-matrix will be presented as well as possible future reactions that can complement our understanding of this scattering reaction. [Preview Abstract] |
Friday, October 14, 2016 5:00PM - 5:12PM |
FE.00006: Cluster Structure and 3-body decay in $^{14}$C Lisa Carpenter, D. Bazin, W. Mittig, Y. Ayyad, S. Beceiro Novo, J. Bradt, T. Ahn, J.J. Kolata, F.D. Becchetti, A. Fritsch Recent model calculations with most advanced methods for cluster states have shown the need of experimental data to probe the structure of light exotic nuclei, including those with $\alpha$-clustering, such as $^{14}$C. The Prototype Active Target Time Projection Chamber (PAT-TPC) allows us to investigate these types of structures, giving access to the full excitation function with a single beam energy. This type of experiment measures resonances in $^{14}$C that can be compared to the models. With an improved Micromegas pad plane with a circular backgammon design we are able to investigate 3-body decays in addition to 2-body scattering. The measurements were carried out by resonant alpha-scattering on $^{10}$Be beam delivered by the {\textit{TwinSol}} facility at the University of Notre Dame. [Preview Abstract] |
Friday, October 14, 2016 5:12PM - 5:24PM |
FE.00007: Probing the cluster structure in $^{10}$Be using resonant $^{6}$He + $\alpha$ scattering Sriteja Upadhyayula, Grigory Rogachev, Ethan Uberseder, Evgeniy Koshchiy, Joshua Hooker, Heshani Jayatissa, Curtis Hunt, Brian Roeder There is strong evidence that some states in $^{10}$Be exhibit molecular like $\alpha$:2n:$\alpha$ configuration. Based on theoretical studies it appears that the $6.179$ MeV 0$^{+}$ state in $^{10}$Be has a pronounced $\alpha$:2n:$\alpha$ configuration with an $\alpha$-$\alpha$ inter-distance of $3.55$ fm [Itagaki and Okabe, (2000)]. This is 1.8 times more than the corresponding value for the $^{10}$Be ground state. The 2$^{+}$ at 7.542 MeV in $^{10}$Be is believed to be the next member of this rotational band. The state at 10.2 MeV was identified as a 4$^{+}$ member in recent experiments. The algebraic model predicts that the terminating member of this band is the 6$^{+}$ state that should be found around 13 MeV. We performed an experiment to search for the 6$^{+}$ state in $^{10}$Be at around 13 MeV excitation energy in the excitation function for $^{6}$He+$\alpha$ scattering. The results of this study will be presented. [Preview Abstract] |
Friday, October 14, 2016 5:24PM - 5:36PM |
FE.00008: Knockout to Probe Proton Contributions to the B(E2) Transition Strength in the C Isotopes Heather Crawford The carbon isotopes represent one of the few cases where it is possible to obtain data from stability to the dripline, and to carry out no-core shell model calculations across the isotopic chain. Thus, data along the Z=6 isotopes can provide stringent constraints and tests of modern nuclear structure theories and the isospin dependence of the underlying nuclear force. One experimental observable along the C chain that provides a sensitive probe of nuclear interactions is the B(E2) electric quadrupole transition strength. In the case of the C isotopes, changes in the observed B(E2) from $^{14}$C to $^{20}$C are understood in terms of a changing proton contribution, rather than decoupling of the valence neutrons from the core as initially postulated. However, to draw final conclusions regarding the extent of any neutron decoupling, it is critical to know how the transition strength is partitioned between the protons and neutrons. Changes and uncertainties in proton occupation will dramatically influence the interpretation. I will report on the results of an experiment carried out at NSCL to probe the amplitude of p-shell protons in the low-lying 2$^{+}_{1}$ states along the C isotopic chain through proton knockout from the corresponding N isotopes. [Preview Abstract] |
Friday, October 14, 2016 5:36PM - 5:48PM |
FE.00009: Nuclear structure corrections for $\mu$4He+ and $\mu$3He+ spectroscopy Nir Nevo Dinur, Chen Ji, Oscar Hernandez, Sonia Bacca, Nir Barnea The proton charge radius was recently determined from muonic hydrogen spectroscopy~[1] with tenfold improved precision but $7.9\sigma$ disagreement with the accepted value, leading to the ``proton radius puzzle''. To further investigate, and to obtain precise radii, these measurements were repeated in $\mu^4$He$^+$ and $\mu^3$He$^+$~[2]. This may also shed light on the discrepancy between isotope-shift measurements of the $^4$He--$^3$He radius difference. However, the precision of radii determined from the muonic experiments is limited by the uncertainties in the nuclear structure corrections~[2]. We present first {\it ab-initio} calculations of these corrections~[3,4] that reduced the uncertainties from $\sim$20\% to the few percent goal.\\ [1] R.~Pohl {\it et al.}, Nature {\bf 466}, 213 (2010); A.~Antognini {\it et al.}, Science {\bf 339}, 417 (2013). [2] M.~Diepold {\it et al.}, arXiv:1606.05231 [physics.atom-ph]. [3] C.~Ji {\it et al.}, Phys.\ Rev.\ Lett.\ {\bf 111}, 143402 (2013). [4] N.~Nevo Dinur {\it et al.}, Phys.\ Lett.\ B {\bf 755}, 380 (2016). [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700