Bulletin of the American Physical Society
2005 2nd Joint Meeting of the Nuclear Physics Divisions of the APS and The Physical Society of Japan
Sunday–Thursday, September 18–22, 2005; Maui, Hawaii
Session KL: Light Ion and EM Reactions |
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Sponsoring Units: DNP JPS Chair: Harutaka Sakaguchi, Kyoto University Room: Ritz-Carlton Hotel Oahu |
Thursday, September 22, 2005 2:00PM - 2:15PM |
KL.00001: $d$-$p$ Elastic Scattering Measurement at Internal Target Station of Nuclotron Tomohiro Uesaka, Vladimir P. Ladygin, Kenji Suda, Yukie Maeda, L.S. Azhgirey, Yu.V. Gurchin, A.Yu. Isupov, Keisuke Itoh, Marian Janek, J.-T. Karachuk, Takahiro Kawabata, A.N. Khrenov, A.S. Kiselev, V. Kizka, J. Kliman, Vladimir A. Krasnov, A.N. Livanov, Alexandre I. Malakhov, S.G. Reznikov, Satoshi Sakaguchi, Hideyuki Sakai, Yoshiko Sasamoto, Kimiko Sekiguchi, Taras A Vasiliev, S. Nedev Measurement of analyzing powers for the $d$-$p$ elastic scattering at energies of 300--2000~MeV will be carried out in June 2005, by use of a polarized deuteron beam from Nuclotron at Dubna. Aim of the measurement is twofold: 1) to investigate energy dependences of the observables for the purpose to clarify spin-dependences of 3N forces. 2) to establish the $d$- $p$ elastic scattering as a deuteron polarimetry in the energy region considered. Results of the measurement together with details of the experimental setup will be reported. [Preview Abstract] |
Thursday, September 22, 2005 2:15PM - 2:30PM |
KL.00002: Bjorken scaling for hadron-nucleus scattering R.J. Peterson Electron scattering to the continuum for several nuclear samples at energy losses less than those for scattering on free nucleons (x$_{Bj} >$1) has been shown to sense high nucleon momenta arising from hard collisions or correlations within nuclei, using ratios of cross sections.\footnote{K. Sh. Egiyan et al., Phys. Rev. C 68, 014313 (2003).} A similar analysis has been carried out for continuum hadron scattering at lower momentum transfers but including a very wide range of nuclei and several reactions, including proton scattering up to 19.2 GeV/c, proton charge exchange, and pion scattering. These data show the same trends as noted with electrons, but heavier nuclei show systematically enhanced contributions from high nucleon momenta. A wide range of data will be compared to the electron results. [Preview Abstract] |
Thursday, September 22, 2005 2:30PM - 2:45PM |
KL.00003: Photodisintegration of Deuterium and Coherent and Incoherent Photoproduction Processes off the Deuteron William Briscoe, Jessica Gohs, Evie Downie, John Annand The MAMI B photon beam with a maximum energy of 855 MeV is used with a liquid deuterium target and the Crystal Ball and TAPS to investigate photodisintegration and photoproduction processes. Among these are coherent $\pi ^{0}$ production on the deuteron itself, $\pi ^{0}$ production off the individual quasi-free nucleons, and the photodisintegration of the deuteron into a proton and a neutron. In addition to providing insight into the properties of the neutron, proton and nucleus, the photodisintegration data is also analyzed to calibrate the neutron efficiency of the Crystal Ball and TAPS detectors in their current configuration at MAMI. We will report on the preliminary physics and calibration results from measurements made with the deuterium target. [Preview Abstract] |
Thursday, September 22, 2005 2:45PM - 3:00PM |
KL.00004: Investigation of Short Range correlations in 3He(e,e$'$pp)n Hovhannes Baghdasaryan, Larry Weinstein Nucleon-Nucleon (NN) Short Range Correlations (SRC) respresent a valuable part of the nuclear wavefunction. The better knowledge of SRC will give us better understanding of nuclear matter and nuclear interactions in extreme conditions. A study of the effects of short-range correlations over the 3He(e,e$'$pp)n reaction measured at Jefferson Lab is presented. Looking at the reaction, we can extract the kinematic regions where the NN SRC is an almost non interacting spectator. We have measured the relative and total momentum distributions of spectator (pp) and (pn) pairs up to 600 MeV/c. We will compare results with various theories. [Preview Abstract] |
Thursday, September 22, 2005 3:00PM - 3:15PM |
KL.00005: Measuring the Spin Structure of $^{3}He$ and the Neutron at Low $Q^{2}$ Timothy Holmstrom The spin structure of the nucleon has been of great interest over the past few decades. Sum rules, including the Gerasimov-Drell-Hearn (GDH), and moments of the nucleon spin structure functions are powerful tools for understanding nucleon structure. The goal of Jefferson Lab experiment E97-110 is to perform a precise measurement of the $Q^{2}$ dependence of the generalized GDH integral, an extension to finite $Q^{2}$ of the GDH sum rule, and the moments of the $^{3}He$ and neutron spin structure functions between 0.02 and 0.3 $(GeV/c)^{2}$. This $Q^{2}$ range will allow us to test the dynamics of Chiral Perturbation Theory, extrapolate to the real photon point for $^{3}He$ and the neutron, and will complement a previous experiment at higher $Q^{2}$. The measurement will also contribute to the understanding of nucleon resonances. The acquisition of data has been completed. Status and prospects will be discussed. [Preview Abstract] |
Thursday, September 22, 2005 3:15PM - 3:30PM |
KL.00006: Tensor Analyzing Powers in Elastic Electron Deuteron Scattering Chi Zhang BLAST Collaboration recently completed its experimental program to measure the tensor analyzing powers in elastic electron deuteron scattering. The experiment was carried out at the South Hall Storage Ring of the MIT-Bates Linear Accelerator Facility with BLAST(Bates Large Acceptance Spectrometer Toroid) detector. An Atomic Beam source is used to inject vector and tensor polarized atomic deuterium gas into an internal target embeded in the electron storage ring. Unprecedented statistical precision is obtained across the $Q^{2}$ range of 0.1 to 0.8 $(GeV/c)^{2}$. Data in various kinematics and momentum transfer are collocted simultaneously along with other reaction channels, including vector polarized observables in e-d elastics scattering. Combined with cross section world data, the new polarized measurement will shed light on the nucleon-nucleon bound state and nucleon-nucleon interaction. Preliminary results for $T_{20}$, $T_{21}$ and the deuteron form factors will be presented. [Preview Abstract] |
Thursday, September 22, 2005 3:30PM - 3:45PM |
KL.00007: Spectroscopy of $^{19}$Na nucleus B.B. Skorodumov, G.V. Rogachev, P. Boutachkov, A. Aprahamian, J.J. Kolata, L.O. Lamm, M. Quinn, A. Woehr Studies of proton-rich nuclei can provide fundamental insights into the properties of nuclear structure and interactions that are not manifest in the valley of stability. Light exotic nuclei are the perfect proving ground for our understanding of the behavior of nuclear matter under extreme proton to neutron ratios. Availability of radioactive beams allows us to use simple reactions such as elastic scattering to populate states in exotic nuclei. I will present results on the spectroscopy of neutron difficient unbound isotope $^{19}$Na. Resonance elastic scattering of $^{18}$Ne on protons was measured using inverse geometry and the very thick target technique [1] The experiment was carried out at the TwinSol radioactive nuclear beam facility of the University of Notre Dame [2]. The beam of $^{18}$Ne was produced via the $^3$He($^{16}$O,$^{18}$Ne)n reaction. The analysis of the excitation function of elastic scattering was carried out with the R-Matrix formalism and Potential model approach. The spectrum of $^{19}$Na was measured up to excitation energy of 2.75 MeV. Results of this work will be compared with the F.de Oliveira et.al.[3] where excitation function was measured up to 6 MeV. \\ 1. K.P. Artemov et al., Sov. J. Nucl. Phys. 52, 408 (1990).\\ 2. M.Y. Lee et. al., Nucl. Instrum. Meth. A422, 536, (1995).\\ 3. F.de Oliveira et. al.,Eur. Phys. J. A 24, 237-247, (2005).\\ [Preview Abstract] |
Thursday, September 22, 2005 3:45PM - 4:00PM |
KL.00008: Coherent Pion Production Measurement from the reaction $^{12}$C(p,n$\pi ^{+})^{12}$C Kunihiro Fujita, Yasuhiro Sakemi, Kichiji Hatanaka, Atsusi Tamii, Youhei Shimizu, Yuji Tameshige, Hiroaki Matsubara, Masaharu Nomachi, Hidehito Nakamura, Tetsuo Noro, Tomotsugu Wakasa, Hidetomo Yoshida, Takashi Ishida, Shun Asaji, Yuji Nagasue The physics goal of our experiment is to measure the Coherent Pion Production (CPP) such as $^{12}$C(p,n$\pi ^{+})^{12}$C(Ground State) and investigate the short range component of the nuclear interaction, which is sensitive to the critical density of pion condensation phase. We performed the test experiment in December, 2004 and May, 2005. Trigger counter for the pion is developed and procedure of coincidence with neutron was established. To identify the CPP event under enormous background, we need tracking detector with high position resolution and radiation tolerance. It can be achieved by Gas Electron Multiplier (GEM) Detector. Then, we developed the GEM detector and its readout electronics called Space Wire readout system for the charged pion measurement. The prototype of the detector is fabricated and basic detector specification is measured. We plan to measure the CPP cross section with full setup including GEM and neutron counter to get quantitative information about the short range component. [Preview Abstract] |
Thursday, September 22, 2005 4:00PM - 4:15PM |
KL.00009: Measurements of Gamow-Teller strength distributions via (t,$^{3}$He) and ($^{3}$He,t) reactions. Remco G.T. Zegers The (t,$^{3}$He) and ($^{3}$He,t) reactions at beam energies exceeding 100 MeV/nucleon are important tools to study the spin-isospin response of nuclei. Of particular interest is the extraction of Gamow-Teller strengths (B(GT)), since these provide direct information about weak-interaction rates that serve as input for stellar evolution calculations. Accurate measurements provide a way to test shell-model codes that can then be used to make estimates for stellar conditions that cannot be achieved in the laboratory. The combined capability to perform high-resolution ($^{3}$He,t) and (t,$^{3}$He) experiments (at RCNP, Osaka and the NSCL, respectively) makes these probes especially suited to perform such studies. The linear relationship between cross section and B(GT) has to be validated experimentally. ($^{3}$He,t) and (t,$^{3}$He)$^{ }$data on a variety of targets will be presented that is used to test the method, focusing on results from $^{26}$Mg($^{3}$He,t) and $^{26}$Mg(t,$^{3}$He) for which Gamow-Teller strengths have extracted over large excitation-energy ranges. [Preview Abstract] |
Thursday, September 22, 2005 4:15PM - 4:30PM |
KL.00010: Studying the ($^{7}$Li,$^{5}$Li) reaction using STARS Lee Bernstein, J.T. Burke, J.A. Church, K. Moody, L.W. Phair, P. Fallon, S. Sinha, M.A. McMahan, M. Wiedeking, R.M. Clark, A.O. Macchiavelli, I.Y. Lee, E. Rodriguez-Vieitez, B. Lyles, S.G. Prussin, H-.C. Ai, C.W. Beausang The LLNL group has been pioneering an effort to determine (n,x) cross sections on unstable nuclei via decay probability measurements of compound nuclei formed using light-ion induced ``surrogate'' reactions. To this end an experiment was performed at the 88-Inch cyclotron at LBNL using the STARS (Silicon Telescope Array for Reaction Studies) spectrometer coupled to LiBeRACE (Livermore-Berkeley Array for Collaborative Experiments) to study using the $^{234,238}$U($^{7}$Li,$^{5}$Li x) reactions to populate neutron-rich compound nuclei. Results from this experiment will be presented and its use for determining (n,x) cross sections on neutron-rich nuclei will be discussed. This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48, Lawrence Berkeley National Laboratory under contract No. DE-AC03-76SF0098 (LBNL) and by the NNSA Stockpile Stewardship Academic Alliance program (Yale/Richmond). [Preview Abstract] |
Thursday, September 22, 2005 4:30PM - 4:45PM |
KL.00011: Deep hole state in $^{6}$He and its cluster structure Yohei Nakatsugawa, Harutaka Sakaguchi, Yuusuke Yasuda, Satoru Terashima, Satoshi Kishi, Juzo Zenihiro, Masaru Yosoi, Mamoru Fujiwara, Kohsuke Nakanishi, Keigo Kawase, Hisanobu Hashimoto, Shun Okumura, Tamio Yamagata, Hidetoshi Akimune, Maki Kinoshita, Shintaro Nakayama, Ken'ichi Fushimi, Masayoshi Tanaka, Hidenori Toyokawa, Masatoshi Itoh, Hidetomo Yoshida, Makoto Uchida The deep-hole state in $^{6}$He was investigated via the quasifree $^7$Li(\textit{p},2\textit{p})$^6$He* reaction with decay coincidence measurements. In general, it is said that light nuclei are described not only by the shell model, but also by the cluster model. In order to investigate their structure, we have measured decay particles from deep-hole states in light nuclei because the direct decay process is dominant and its decay mode gives us imformation on the structure of deep-hole states. In this experiment, Triton decay was found to be dominant for the so-called \textit{s}-hole state in $^6$He contrary to the shell model calculation. This result implies the tri-nucleon cluster structure in $^{6}$He(\textit{s}-hole), which is created by knocking out a proton from an $\alpha$ in $^{7}$Li(gnd). [Preview Abstract] |
Thursday, September 22, 2005 4:45PM - 5:00PM |
KL.00012: Chiral Symmetry Breaking in Pion Double Charge Exchange Roman Kezerashvili We study the energy behavior of the forward pion double charge exchange reaction on atomic nuclei in the framework of meson exchange currents (MEC) mechanism. Different chiral symmetry breaking Lagrangians are used to describe pion--pion vertex and vertex corresponding to a seagull diagram. To investigate the energy dependence of meson exchange currents contribution we neglected pion distortion. Our analytical calculations show that matrix elements for a forward differential cross section do not depend on the energy of the incoming pion. However, the amplitudes of the MEC diagrams considered depend on the chiral symmetry breaking parameter. The comparison of the sequential and the meson exchange current mechanisms shows that both mechanisms have a comparable contribution to the differential cross section at zero degree at the high energy region. [Preview Abstract] |
Thursday, September 22, 2005 5:00PM - 5:15PM |
KL.00013: Double-Spin Asymmetry of \textit{J/$\psi $} $\to $ \textit{$\mu $}$^{+}$\textit{$\mu $}$^{{\-}}$ in longitudinally polarized $p+p$ collisions at $\surd s$ = 200 GeV Imran Younus Polarized DIS experiments have established that the spin carried by quarks and anti-quarks in the proton does not account for the total proton spin. The gluon polarization and orbital angular momentum of the partons are other possible contributors, but remain largely inaccessible through the virtual photon probes of DIS. Heavy-quark pair production, including \textit{J/$\psi $} production in polarized $p+p$ collisions at RHIC is dominated by gluon-gluon interactions and provide direct access to the gluon polarization in the proton. The muon spectrometers at the PHENIX experiment can measure \textit{J/$\psi $} yields through the \textit{$\mu $}$^{+}$\textit{$\mu $}$^{-}$ decay mode at large rapidity (1.2 $< {\mid}{\eta}{\mid} <$ 2.2). In this talk we present the current status of the analysis of the double longitudinal spin asymmetry $A_{LL}$ in the \textit{J/$\psi $ }yields in polarized $p+p$ collisions at $\surd s$ = 200 GeV, using the data obtained in 2005. The integrated luminosity is expected to be $\sim $4 \textit{pb}$^{-1}$ with average polarization of 50{\%}. [Preview Abstract] |
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