Mon·Nov 18, 2019Monday·November 18, 2019

1. 01*

   Lifetimes and moments measurements to investigate the structure of midheavy nuclei

   T.J. Mertzimekis🇬🇷 · A. Khaliel · D. Papaioannou · G. Zagoraios · A. Zyriliou

   Mid-heavy nuclei offer unique opportunities to study the collective and single-particle aspects of nuclear structure. This mass regime is a dynamic area where protons and neutrons generally occupy different orbitals, giving rise to complex structures with a wide variety of shapes, shape evolution and shape coexistence. To that end, measurements of nuclear lifetimes and electromagnetic moments ($\mu$,$Q$) can be invaluable. Recent experimental activities of the NuSTRAP group in Athens have focused on $\gamma$-spectroscopy studies employing the RoSPHERE array in Magurele, Romania. In recent studies [1,2], the neutron-rich ${}^{144-146}$Ba isotopes have exhibited octupole degrees of freedom. Similar questions exist for the lighter ${}^{140}$Ba isotope, which is located at the onset of octupole collectivity. In addition, understanding the structure of heavier, even-even hafnium isotopes requires more data regarding shape coexistence and shape evolution. Preliminary results on lifetimes in this area pave the way to understand dynamical phenomena prior to studying more exotic species in the future.

   nucl-exnucl-thBulg.J.Phys.(2019)·0 citations
2. 02*

   Role of the $\Lambda (1600)$ in the $K^{-}p\to \Lambda {\pi }^0{\pi }^0$ reaction

   He Zhou🇨🇳 · Ju-Jun Xie🇨🇳

   Role of the $\Lambda (1600)$ is studied in the $K^{-}p\to \Lambda {\pi }^0{\pi }^0$ reaction by using the effective Lagrangian approach near the threshold. We perform a calculation for the total and differential cross sections by considering the contributions from the $\Lambda (1600)$ and $\Lambda (1670)$ intermediate resonances decaying into ${\pi }^0{\Sigma }^{\ast 0}(1385)$ with ${\Sigma }^{\ast 0}(1385)$ decaying into ${\pi }^0\Lambda$. Besides, the non-resonance process from $u$-channel nucleon pole is also taken into account. With our model parameters, the current experimental data on the total cross sections of the $K^{-}p\to \Lambda {\pi }^0{\pi }^0$ reaction can be well reproduced. It is shown that we really need the contribution from the $\Lambda (1600)$ with spin-parity $J^P=1/2^{+}$, and that these measurements can be used to determine some of the properties of the $\Lambda (1600)$ resonance. Furthermore, we also plot the ${\pi }^0\Lambda$ invariant mass distributions which could be tested by the future experimental measurements.

   ↳ hep-phhep-exnucl-exnucl-thCommun.Theor.Phys.(2020)·2 citations
3. 03*

   Conceptual Design of a Polarized 3He Target for the CLAS12 Spectrometer

   James Maxwell🇺🇸 · Richard Milner🇺🇸

   We present a conceptual design for a polarized ${}^3$He target for Jefferson Lab's CLAS12 spectrometer in its standard configuration. This two-cell target will take advantage of advancements in optical pumping techniques at high magnetic field to create 60\% longitudinally polarized ${}^3$He gas in a pumping cell inside the CLAS12 5 T solenoid. By transferring this gas to a 20 cm long, 5 K target cell, a target thickness of $3\times 10^{21}$ ${}^3$He/cm${}^2$ will be produced, reaching the detector's specified maximum luminosity with a beam current of 2.5 $\mu A$.

   ↳ physics.ins-detnucl-ex2 citations
4. 04*

   Novel multi-layer plastic-scintillator-based solid active proton target for inverse-kinematics experiments

   D. T. Tran🇻🇳 · S. Terashima🇨🇳 · H. J. Ong🇯🇵 · K. Hirakawa · Y. Matsuda🇯🇵 · N. Aoi🇯🇵 · M. N. Harakeh🇳🇱 · M. Itoh🇯🇵 · T. Kawabata · A. Kohda · S. Y. Matsumoto🇯🇵 · T. Nishi🇯🇵 · J. Okamoto🇯🇵 · I. Tanihata

   We have constructed and tested a novel plastic-scintillator-based solid-state active proton target for use in nuclear spectroscopic studies with nuclear reactions induced by an ion beam in inverse kinematics. The active target system, named Stack Structure Solid organic Scintillator Active Target (S4AT), consists of five layers of plastic scintillators, each with a 1-mm thickness. To determine the reaction point in the thickness direction, we exploit the difference in the energy losses due to the beam particle and the charged reaction product(s) in the scintillator material. S4AT offers the prospect of a relatively thick target while maintaining a good energy resolution. By considering the relative energy loss between different layers, the energy loss due to unreacted beam particles can be eliminated. Such procedure, made possible by the multi-layer structure, is essential to eliminate the effect of unreacted accompanying beam particles, thus enabling its operation at a moderate beam intensity of up to a few Mcps. We evaluated the performance of S4AT by measuring the elastic proton-proton scattering using a 70-MeV proton beam at Cyclotron and Radioisotope Center (CYRIC), Tohoku University.

   ↳ physics.ins-detnucl-exphysics.acc-phNucl.Instrum.Meth.A(2020)·0 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.