Fri·Jun 14, 2019Friday·June 14, 2019

1. 01*

   Nuclear Mass Measurements With Radioactive Ion Beams

   Michael A. Famiano🇺🇸

   Nuclear masses are the most fundamental of all nuclear properties, yet they can provide a wealth of knowledge, including information on astrophysical sites, constraints on existing theory, and fundamental symmetries. In nearly all applications, it is necessary to measure nuclear masses with very high precision. As mass measurements push to more short-lived and more massive nuclei, the practical constraints on mass measurement techniques become more exacting. Various techniques used to measure nuclear masses, including their advantages and disadvantages are described. Descriptions of some of the world facilities at which the nuclear mass measurements are performed are given, and brief summaries of planned facilities are presented. Future directions are mentioned, and conclusions are presented which provide a possible outlook and emphasis on upcoming plans for nuclear mass measurements at existing facilities, those under construction, and those being planned.

   nucl-exastro-ph.IMIJMPE(2019)·6 citations
2. 02*

   Nucleon Resonances with Hidden Charm in $\gamma p$ reactions

   Jia-Jun Wu🇨🇳 · T.-S. H. Lee🇺🇸 · Bing-Song Zou🇨🇳

   The excitations of nucleon resonances with hidden charm, $N_{c\bar{c}}^{\ast }$, in the $\gamma p$ reactions are investigated by using the predictions from the available meson-baryons (MB) coupled-channel models. For the $\gamma p\to J/\psi p$ process, we first calculate the Pomeron-exchange amplitudes with the parameters determined from fitting the available total cross section data up to invariant mass $W=300$ GeV. We then add the resonant amplitudes to examine the effects of $N_{c\bar{c}}^{\ast }$ excitations on the cross sections of $\gamma p\to J/\psi p$ in the near threshold energy region. The $N_{c\bar{c}}^{\ast }\to MB$ transition matrix elements are determined from the partial decay widths predicted by the meson-baryons coupled-channel models. The $\gamma p\to N_{c\bar{c}}^{\ast }$ transition amplitudes are calculated from the Vector Meson Dominance (VMD) model. The total $\gamma p\to J/\psi p$ amplitudes then depend on an off-shell form factor, parameterized as $F_V(q^2)={\Lambda }^4/({\Lambda }^4+(q^2-m_V^2{)}^2)$ with $\Lambda =550$ MeV. We then demonstrate that the $N_{c\bar{c}}^{\ast }$ can be most easily identified in the differential cross sections at large angles of outgoing $J/\psi$ where the contribution from Pomeron-exchange becomes negligible. With the same VMD model and the same coupled-channel models of $N_{c\bar{c}}^{\ast }$, we also calculate the resonant amplitudes for the $\gamma p\to Vp\to N_{c\bar{c}}^{\ast }\to {\bar{D}}^0{\Lambda }_c^{+}({\bar{D}}^{\ast 0}{\Lambda }_c^{+})$ processes. By adding the non-resonant amplitudes due to the exchange of ${\bar{D}}^{\ast 0}$ (${\bar{D}}^0)$, we then predict the cross sections of $\gamma p\to {\bar{D}}^0{\Lambda }_c^{+}({\bar{D}}^{\ast 0}{\Lambda }_c^{+})$ for additional experimental tests of the available meson-baryon coupled-channel models of $N_{c\bar{c}}^{\ast }$.

   ↳ nucl-thnucl-exPRC(2019)·61 citations
3. 03*

   Prompt Neutron Multiplicity Distributions Inferred from $\gamma$-ray and Fission Fragment Energy Measurements

   A.E. Lovell🇺🇸 · I. Stetcu🇺🇸 · P. Talou🇺🇸 · G. Rusev🇺🇸 · M. Jandel

   We propose a novel method to extract the prompt neutron multiplicity distribution, $P(\nu )$, in fission reactions based on correlations between prompt neutrons, $\gamma$ rays, and fragment kinetic energy arising from energy conservation. In this approach, only event-by-event measurements of the total $\gamma$-ray energy released as a function of the total kinetic energy (TKE) of the fission fragments are performed, and no neutron detection is required. Using the $\text{CGMF}$ fission event generator, we illustrate the method and explore the accuracy of extracting the neutron multiplicity distribution when taking into account the energy resolution and calibration of the energy measurements. We find that a TKE resolution of under 2 MeV produces reasonably accurate results, independent of typical $\gamma$-ray energy measurement resolution.

   ↳ nucl-thnucl-exPRC(2019)·0 citations
4. 04*

   Measuring the Gain of a Micro-Channel Plate/Phosphor Assembly Using a Convolutional Neural Network

   Michael Jones · Matthew Harvey · William Bertsche · Andrew James Murray · Robert B. Appleby🇬🇧

   This paper presents a technique to measure the gain of a single-plate micro-channel plate (MCP)/phosphor assembly by using a convolutional neural network to analyse images of the phosphor screen, recorded by a charge coupled device. The neural network reduces the background noise in the images sufficiently that individual electron events can be identified. From the denoised images, an algorithm determines the average intensity recorded on the phosphor associated with a single electron hitting the MCP. From this average single-particle-intensity, along with measurements of the charge of bunches after amplification by the MCP, we were able to deduce the gain curve of the MCP.

   ↳ physics.ins-detnucl-exphysics.acc-phphysics.data-anIEEE Trans.Nucl.Sci.(2019)·1 citation
5. 05*

   Production of electrons from heavy-flavour hadron decays in different collision systems with ALICE at LHC

   Sudhir Pandurang Rode (for the ALICE Collaboration)🇮🇳

   Heavy-flavour quarks, due to their large masses, are produced in the early stages of the relativistic heavy-ion collisions via initial hard scatterings. Therefore, as they experience the full system evolution, heavy quarks are effective probes of the hot and dense medium created in such collisions. In pp collisions, the measurement of heavy-flavour hadron production cross sections can be used to test our understanding of the Quantum ChromoDynamics (QCD) in the perturbative regime. Also, pp collisions provide a crucial reference for the corresponding measurements in larger systems. In Pb--Pb (Xe--Xe) collisions, the measurement of the nuclear modification factor of heavy-flavour hadrons provides information on the modification of the invariant yield with respect to pp collisions due to the produced cold and hot QCD matter. The possible mass dependence of the parton energy loss can be studied by comparing the $R_{\mathrm{AA}}$ of pions, charm and beauty hadrons. In this contribution, recent results from ALICE at the LHC are reported with focus on the different measurements of the heavy-flavour electrons in pp collisions at 2.76, 5.02, 7 and 13 TeV and in Pb--Pb (Xe--Xe) collisions at 5.02 (5.44) TeV. The results include the differential production cross sections and nuclear modification factors of heavy-flavour electrons at mid-rapidity. The comparison of experimental data with model predictions is discussed.

   ↳ hep-exnucl-exSpringer Proc.Phys.(2021)·2 citations
6. 06*

   Precision measurement of atomic isotope shifts using a two-isotope entangled state

   Tom Manovitz🇮🇱 · Ravid Shaniv🇮🇱 · Yotam Shapira🇮🇱 · Roee Ozeri🇮🇱 · Nitzan Akerman🇮🇱

   Atomic isotope shifts (ISs) are the isotope-dependent energy differences in the atomic electron energy levels. These shifts serve an important role in atomic and nuclear physics, and particularly in the latter as signatures of nuclear structure. Recently ISs have been suggested as unique probes of beyond Standard Model (SM) physics, under the condition that they be determined significantly more precisely than current state of the art. In this work we present a simple and robust method for measuring ISs with ions in a Paul trap, by taking advantage of Hilbert subspaces that are insensitive to common-mode noise yet sensitive to the IS. Using this method we evaluate the IS of the $5S_{1/2}\leftrightarrow 4D_{5/2}$ transition in ${}^{86}{\text{Sr}}^{+}$ and ${}^{88}{\text{Sr}}^{+}$ with a $1.6\times 10^{-11}$ relative uncertainty to be 570,264,063.435(9) Hz. Furthermore, we detect a relative difference of $3.46(23)\times 10^{-8}$ between the orbital g-factors of the electrons in the $4D_{5/2}$ level of the two isotopes. Our method is relatively easy to implement and is indifferent to element or isotope, paving the way for future tabletop searches for new physics and posing interesting prospects for testing quantum many-body calculations and for the study of nuclear structure.

   ↳ physics.atom-phhep-exnucl-exquant-phPRL(2019)·61 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.