Tue·Jul 28, 2020Tuesday·July 28, 2020

1. 01*

   Overestimated isomer depletion due to contamination

   Song Guo🇨🇳 · Yongde Fang🇨🇳 · Xiaohong Zhou🇨🇳 · C. M. Petrache🇫🇷

   The recent paper by Chiara et al. provided the first experimental evidence of nuclear excitation by electron capture (NEEC), responding a long-standing theoretical prediction. NEEC was inferred to be the main channel to excite an isomer in Molybdenum-93 to a higher state, leading to a rapid release of full isomer energy (isomer depletion). The deduced large excitation probability $P_{exc}$=0.010(3) for this mechanism implied strong influence on the survival of nuclei in stellar environments. However, the excitation probability is much higher than the estimated NEEC probability $P_{NEEC}$ according to a following theoretical work by approximately 9 orders of magnitude. Nevertheless, the reported $P_{exc}$ is predicted to be due to other unknown mechanism causing isomer depletion, which is expected to open up a new era of the storage and release of nuclear energy. Here we report an analysis of the reported experimental results, showing that the observed isomer depletion is significantly overestimated due to the contamination.

   nucl-exNature(2021)·21 citations
2. 02*

   Experimental techniques to study the $\gamma$ process for nuclear astrophysics at the Cologne accelerator laboratory

   F. Heim · J. Mayer🇩🇪 · M. Müller🇩🇪 · P. Scholz · M. Weinert🇩🇪 · A. Zilges🇩🇪

   The nuclear astrophysics setup at the Institute for Nuclear Physics, University of Cologne, Germany is dedicated to measurements of total and partial cross sections of charged-particle induced reactions at astrophysically relevant energies. These observables are key ingredients for reaction network calculations of various stellar scenarios, and crucial for the understanding of the nucleosynthesis of elements. The experiments utilize the high-efficiency $\gamma$-ray spectrometer HORUS, and the 10 MV FN-Tandem accelerator. An updated target chamber as well as further experimental methods established in the last years will be presented which allow to measure cross sections down to the nb region. The reliability of the measured cross sections is proven by a ${}^{89}$Y(p,$\gamma$)${}^{90}$Zr commissioning experiment. Additionally, an application for nuclear astrophysics will be presented. The results of a ${}^{93}$Nb(p,$\gamma$)${}^{94}$Mo experiment will be discussed as well as their deviations compared to formerly reported results.

   nucl-exNucl.Instrum.Meth.A(2020)·12 citations
3. 03*

   Multi-step processes in heavy-ion induced single-nucleon transfer reactions

   N. Keeley · K. W. Kemper🇺🇸 · K. Rusek

   It was first noted during the 1970s that finite-range distorted wave Born approximation (FR-DWBA) calculations were unable satisfactorily to describe the shape of the angular distributions of many single-proton (and some single-neutron) transfer reactions induced by heavy ions, with calculations shifted to larger angles by up to ~ 4 degrees compared with the data. These reactions exhibited a significant mismatch, either of the reaction Q value or the grazing angular momentum of the entrance and exit channels, and it was speculated that the inclusion of multi-step transfer paths via excited state(s) of the projectile and/or ejectile could compensate for the effect of this mismatch and yield good descriptions of the data by shifting the calculated peaks to smaller angles. However, to date this has not been explicitly demonstrated for many reactions. In this work we show that inclusion of the two-step transfer path via the 4.44-MeV 2+ excited state of the 12C projectile in coupled channel Born approximation calculations enables a good description of the 208Pb(12C,11B)209Bi single-proton stripping data at four incident energies which could not be described by the FR-DWBA. We also show that inclusion of a similar reaction path for the 208Pb(12C,13C)207Pb single-neutron pickup reaction has a relatively minor influence, slightly improving the already good description obtained with the FR-DWBA.

   nucl-exnucl-thPRC(2020)·4 citations
4. 04*

   High-precision mass measurement of ${}^{168}$Yb for verification of nonlinear isotope shift

   D.A. Nesterenko🇫🇮 · R.P. de Groote🇫🇮 · T. Eronen🇫🇮 · Z. Ge🇫🇮 · M. Hukkanen🇫🇮 · A. Jokinen🇫🇮 · A. Kankainen🇫🇮

   The absolute mass value of ${}^{168}$Yb has been directly determined with the JYFLTRAP Penning trap mass spectrometer at the Ion Guide Isotope Separator On-Line (IGISOL) facility. A more precise value of the mass of ${}^{168}$Yb is needed to extract possible signatures of beyond standard model physics from high-precision isotope shift measurements of Yb atomic transition frequencies. The measured mass-excess value, ME(${}^{168}$Yb) = $-$61579.846(94) keV, is 12 times more precise and deviates from the Atomic Mass Evaluation 2016 value by 1.7$\sigma$. The impact on precision isotope shift studies of the stable Yb isotopes is discussed.

   nucl-exInt.J.Mass Spectrometry(2020)·9 citations
5. 05*

   Open heavy-flavour production from small to large collision systems with ALICE at the LHC

   Fabio Catalano (for the ALICE Collaboration)🇮🇹

   Heavy quarks are effective probes of the hot and dense nuclear matter, the quark-gluon plasma, produced in ultra-relativistic heavy-ion collisions. Due to the short time scale characterising their production, heavy quarks experience the whole evolution of the system. In particular, measurements of heavy-flavour hadron production in Pb-Pb collisions at LHC energies give insight into the mechanisms of heavy-quark transport in the deconfined matter. In small hadronic systems, pp and p-Pb collisions, heavy-flavour measurements provide the baseline for observations of hot-medium effects in heavy-ion collisions, as well as tests of perturbative quantum chromodynamic calculations and measurements of cold-nuclear-matter effects. In this contribution, recent ALICE results on open heavy-flavour hadron production in pp, p-Pb and Pb-Pb collisions at various energies are discussed. New measurements are presented both for fully-reconstructed charmed hadrons and for single electrons from heavy-flavour hadron decays, also investigating the beauty-quark production via the measurement of D mesons and electrons from beauty-hadron decays.

   nucl-exPoS(2021)·2 citations
6. 06*

   Augmented Signal Processing in Liquid Argon Time Projection Chambers with a Deep Neural Network

   Haiwang Yu🇺🇸 · Mary Bishai🇺🇸 · Wenqiang Gu🇺🇸 · Meifeng Lin🇺🇸 · Xin Qian🇺🇸 · Yihui Ren🇺🇸 · Andrea Scarpelli🇺🇸 · Brett Viren🇺🇸 · Hanyu Wei🇺🇸 · Hongzhao Yu🇨🇳 · Kwang Min Yu🇺🇸 · Chao Zhang🇺🇸

   The Liquid Argon Time Projection Chamber (LArTPC) is an advanced neutrino detector technology widely used in recent and upcoming accelerator neutrino experiments. It features a low energy threshold and high spatial resolution that allow for comprehensive reconstruction of event topologies. In current-generation LArTPCs, the recorded data consist of digitized waveforms on wires produced by induced signal on wires of drifting ionization electrons, which can also be viewed as two-dimensional (2D) (time versus wire) projection images of charged-particle trajectories. For such an imaging detector, one critical step is the signal processing that reconstructs the original charge projections from the recorded 2D images. For the first time, we introduce a deep neural network in LArTPC signal processing to improve the signal region of interest detection. By combining domain knowledge (e.g., matching information from multiple wire planes) and deep learning, this method shows significant improvements over traditional methods. This work details the method, software tools, and performance evaluated with realistic detector simulations.

   ↳ physics.ins-dethep-exnucl-exJINST(2021)·14 citations
7. 07*

   Lepton-jet Correlation in Deep Inelastic Scattering

   Xiaohui Liu🇨🇳 · Felix Ringer🇺🇸 · Werner Vogelsang🇩🇪 · Feng Yuan🇺🇸

   We study the lepton-jet correlation in deep inelastic scattering. We perform one-loop calculations for the spin averaged and transverse spin dependent differential cross sections depending on the total transverse momentum of the final state lepton and the jet. The transverse momentum dependent (TMD) factorization formalism is applied to describe the relevant observables. To show the physics reach of this process, we perform a phenomenological study for HERA kinematics and comment on an ongoing analysis of experimental data. In addition, we highlight the potential of this process to constrain small-$x$ dynamics.

   ↳ hep-phhep-exnucl-exPRD(2020)·61 citations
8. 08*

   Importance of Multiplicity Fluctuations in Entropy Scaling

   Patrick Carzon🇺🇸 · Matthew D. Sievert🇺🇸 · Jacquelyn Noronha-Hostler🇺🇸

   One of the greatest uncertainties in heavy-ion collisions is the description of the initial state. Different models predict a wide range of initial energy density distributions based on their underlying assumptions. Final flow harmonics are sensitive to these differences in the initial state due to the nearly linear mapping between eccentricities and anisotropic flow harmonics. The Trento code uses a model-agnostic approach by phenomenologically parameterizing the initial state and constraining those parameters from a Bayesian analysis. There the multiplicity fluctuations were determined by a one parameter $\Gamma$ distribution. However, initial-state models arising from the Color-Glass Condensate (CGC) framework lead to an initial energy density which is outside the functional form considered in Trento and its later Bayesian analyses because they rely on log-normal multiplicity fluctuations. We compare $T_A{T}_B$ scaling (CGC-like) to $\sqrt{T_A{T}_B}$ scaling (preferred from a Trento Bayesian analysis) and find that the $T_A{T}_B$ form together with log-normal fluctuations is a reasonable candidate to describe the multiplicity fluctuations but leads to larger eccentricities, which would affect the extraction of viscosity in small systems.

   ↳ nucl-thhep-phnucl-exPoS(2021)·5 citations
9. 09*

   Simulating hadron test beams in liquid argon

   Alexander Friedland (SLAC)🇺🇸 · Shirley Weishi Li (SLAC)🇺🇸

   Thorough modeling of the physics involved in liquid argon calorimetry is essential for accurately predicting the performance of DUNE and optimizing its design and analysis pipeline. At the fundamental level, it is essential to quantify the detector response to individual hadrons---protons, charged pions, and neutrons---at different injection energies. We report such a simulation, analyzed under different assumptions about event reconstruction, such as particle identification and neutron detection. The role of event containment is also quantified. The results of this simulation can help inform the ProtoDUNE test-beam data analysis, while also providing a framework for assessing the impact of various cross section uncertainties.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2020)·12 citations
10. 10*

    Improved calculations of beta decay backgrounds to new physics in liquid xenon detectors

    Scott Haselschwardt🇺🇸 · Joel Kostensalo🇫🇮 · Xavier Mougeot🇫🇷 · Jouni Suhonen🇫🇮

    We present high-precision theoretical predictions for the electron energy spectra for the ground-state to ground-state $\beta$ decays of ${}^{214}$Pb, ${}^{212}$Pb, and ${}^{85}$Kr most relevant to the background of liquid xenon dark matter detectors. The effects of nuclear structure on the spectral shapes are taken into account using large-scale shell model calculations. Final spectra also include atomic screening and exchange effects. The impact of nuclear structure effects on the ${}^{214}$Pb and ${}^{212}$Pb spectra below $\approx 100$ keV, pertinent for several searches for new physics, are found to be comparatively larger than those from the atomic effects alone. We find that the full calculation for ${}^{214}$Pb (${}^{212}$Pb) predicts 15.0-23.2% (12.1-19.0%) less event rate in a 1-15 keV energy region of interest compared to the spectrum calculated as an allowed transition when using values of the weak axial vector coupling in the range $g_{\mathrm{A}}=0.7-1.0$. The discrepancy highlights the importance of both a proper theoretical treatment and the need for direct measurements of these spectra for a thorough understanding of $\beta$ decay backgrounds in future experiments.

    ↳ hep-exnucl-exPRC(2020)·45 citations
11. 11*

    Discovering partonic rescattering in light nucleus collisions

    Alexander Huss🇨🇭 · Aleksi Kurkela🇨🇭 · Aleksas Mazeliauskas🇨🇭 · Risto Paatelainen🇨🇭 · Wilke van der Schee🇨🇭 · Urs Achim Wiedemann🇨🇭

    We demonstrate that oxygen-oxygen (OO) collisions at the LHC provide unprecedented sensitivity to parton energy loss in a system whose size is comparable to those created in very peripheral heavy-ion collisions. With leading and next-to-leading order calculations of nuclear modification factors, we show that the baseline in the absence of partonic rescattering is known with up to 2% theoretical accuracy in inclusive OO collisions. Surprisingly, a $Z$-boson normalized nuclear modification factor does not lead to higher theoretical accuracy within current uncertainties of nuclear parton distribution functions. We study a broad range of parton energy loss models and we find that the expected signal of partonic rescattering can be disentangled from the baseline by measuring charged hadron spectra in the range $20\text{GeV}<p_T<100\text{GeV}$

    ↳ hep-phhep-exnucl-exnucl-thPRL(2021)·75 citations
12. 12*

    Predicting parton energy loss in small collision systems

    Alexander Huss🇨🇭 · Aleksi Kurkela🇨🇭 · Aleksas Mazeliauskas🇨🇭 · Risto Paatelainen🇨🇭 · Wilke van der Schee🇨🇭 · Urs Achim Wiedemann🇨🇭

    Medium induced parton energy loss is not conclusively established neither in very peripheral heavy-ion collisions nor in proton-ion collisions. However, the standard interpretation of azimuthal momentum anisotropies in theses systems implies some partonic rescattering. The upcoming light-ion runs at the LHC provide a unique opportunity to search for parton energy loss in different systems of similar size. Here, we make predictions for the expected parton energy loss signal in the charged hadron spectra in a system size scan at LHC. We test a large set of model assumptions against the transverse momentum and centrality dependence of the charged hadron nuclear modification factor in lead-lead and xenon-xenon collisions at the LHC. We then attempt to make a model agnostic prediction for the charged hadron nuclear modification factor in oxygen-oxygen collisions.

    ↳ hep-phhep-exnucl-exnucl-thPRC(2021)·87 citations
13. 13*

    Separation of atomic and molecular ions by ion mobility with an RF carpet

    Ivan Miskun🇩🇪 · Timo Dickel🇩🇪 · Samuel Ayet San Andres🇩🇪 · Julian Bergmann🇩🇪 · Paul Constantin🇷🇴 · Jens Ebert🇩🇪 · Hans Geissel🇩🇪 · Florian Greiner🇩🇪 · Emma Haettner🇩🇪 · Christine Hornung🇩🇪 · Wayne Lippert🇩🇪 · Israel Mardor🇮🇱 and 7 other authors

    Gas-filled stopping cells are used at accelerator laboratories for the thermalization of high-energy radioactive ion beams. Common challenges of many stopping cells are a high molecular background of extracted ions and limitations of extraction efficiency due to space-charge effects. At the FRS Ion Catcher at GSI, a new technique for removal of ionized molecules prior to their extraction out of the stopping cell has been developed. This technique utilizes the RF carpet for the separation of atomic ions from molecular contaminant ions through their difference in ion mobility. Results from the successful implementation and test during an experiment with a 600~MeV/u ${}^{124}$Xe primary beam are presented. Suppression of molecular contaminants by three orders of magnitude has been demonstrated. Essentially background-free measurement conditions with less than $1\%$ of background events within a mass-to-charge range of 25 u/e have been achieved. The technique can also be used to reduce the space-charge effects at the extraction nozzle and in the downstream beamline, thus ensuring high efficiency of ion transport and highly-accurate measurements under space-charge-free conditions.

    ↳ physics.ins-detnucl-exInt.J.Mass Spectrometry(2021)·5 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.