Wed·Mar 3, 2021Wednesday·March 3, 2021

1. 01*

   Study of $s$- and $d$-wave intruder strengths in ${}^{13}{\mathrm{B}}_{g.s.}$ via a $p{(}^{13}\mathrm{B},d{)}^{12}\mathrm{B}$ reaction

   W. Liu · J. L. Lou🇨🇳 · Y. L. Ye🇨🇳 · Z. H. Li🇨🇳 · Q. T. Li🇨🇳 · H. Hua🇨🇳 · X. F. Yang🇨🇳 · J. Y. Xu🇨🇳 · H. J. Ong🇨🇳 · D. T. Tran · N. Aoi🇯🇵 · E. Ideguchi🇯🇵 and 15 other authors

   Experimental results of the $p{(}^{13}\mathrm{B},d{)}^{12}\mathrm{B}$ transfer reaction to the low-lying states in ${}^{12}$B are reported. The optical potential parameters for the entrance channel are extracted from the elastic scattering $p$(${}^{13}\mathrm{B}$, $p$) measured in the same experiment, while those for the exit channel are global ones. Spectroscopic factors associated with the $p$-, $s$-, and $d$-wave neutron transfer to the known ${}^{12}$B states, are extracted by comparing the deuteron angular distributions with the calculation results. The separated $s$- and $d$-wave intruder strengths in ${}^{13}{\mathrm{B}}_{g.s.}$ were determined to be $10(2)\%$ and $6(1)\%$, respectively, which follow roughly the systematics for the $N$ = 8 neutron-rich isotones. The measured total intruder strength is in good agreement with the shell model calculation, while the individual ones evolve quite differently. Particularly, the sudden change of the $d$-wave intensity between ${}^{13}$B and ${}^{12}$Be needs further theoretical interpretation.

   nucl-ex0 citations
2. 02*

   Tests of collectivity in ${}^{98}$Zr by absolute transition rates

   V. Karayonchev🇩🇪 · J. Jolie🇩🇪 · A. Blazhev🇩🇪 · A. Dewald🇩🇪 · A. Esmaylzadeh🇩🇪 · C. Fransen🇩🇪 · G. Häfner🇩🇪 · L. Knafla🇩🇪 · J. Litzinger🇩🇪 · C. Müller-Gatermann🇩🇪 · J.-M. Régis🇩🇪 · K. Schomacker🇩🇪 and 4 other authors

   Lifetimes of low-spin excited states in ${}^{98}$Zr were measured using the recoil-distance Doppler-shift technique and the Doppler-shift attenuation method. The nucleus of interest was populated in a ${}^{96}$Zr(${}^{18}$O,${}^{16}$O)${}^{98}$Zr two-neutron transfer reaction at the Cologne FN Tandem accelerator. Lifetimes of six low-spin excited states, of which four are unknown, were measured. The deduced $B(E2)$ values were compared with Monte Carlo shell model and interacting boson model with configuration mixing calculations. Both approaches reproduce well most of the data but leave challenging questions regarding the structure of some low lying states.

   nucl-exnucl-thPRC(2020)·30 citations
3. 03*

   Reevaluating reactor antineutrino spectra with new measurements of the ratio between ${}^{235}$U and ${}^{239}$Pu $\beta$ spectra

   V. Kopeikin🇷🇺 · M. Skorokhvatov🇷🇺 · O. Titov🇷🇺

   We report a reanalysis of the reactor antineutrino energy spectra based on the new relative measurements of the ratio $R={}^e{S}_5{/}^e{S}_9$ between cumulative $\beta$ spectra from ${}^{235}$U and ${}^{239}$Pu, performed at a research reactor in National Research Centre Kurchatov Institute (KI). A discrepancy with the $\beta$ spectra measured at Institut Laue-Langevin (ILL) was observed, indicating a steady excess of the ILL ratio by the factor of $1.054\pm 0.002$. We find a value of the ratio between inverse beta decay cross section per fission for ${}^{235}$U and ${}^{239}$Pu: ${(}^5{\sigma }_f{/}^9{\sigma }_f{)}_{KI}=1.45\pm 0.03$, and then we reevaluate the converted antineutrino spectra for ${}^{235}$U and ${}^{238}$U. We conclude that the new predictions are consistent with the results of Daya Bay and STEREO experiments.

   nucl-exhep-phnucl-thPRD(2021)·121 citations
4. 04*

   Form Factors and Two-Photon Exchange in High-Energy Elastic Electron-Proton Scattering

   M. E. Christy · T. Gautam · L. Ou · B. Schmookler · Y. Wang · D. Adikaram · Z. Ahmed · H. Albataineh · S. F. Ali · B. Aljawrneh · K. Allada · S.L. Allison and 158 other authors

   We present new precision measurements of the elastic electron-proton scattering cross section for momentum transfer (Q${}^2$) up to 15.75~\gevsq. Combined with existing data, these provide an improved extraction of the proton magnetic form factor at high Q${}^2$ and double the range over which a longitudinal/transverse separation of the cross section can be performed. The difference between our results and polarization data agrees with that observed at lower Q${}^2$ and attributed to hard two-photon exchange (TPE) effects, extending to 8~(GeV/c)${}^2$ the range of Q${}^2$ for which a discrepancy is established at $>$95\% confidence. We use the discrepancy to quantify the size of TPE contributions needed to explain the cross section at high Q${}^2$.

   nucl-exhep-exPRL(2022)·46 citations
5. 05*

   Main magnetic focus ion source: Device with high electron current density

   V.P. Ovsyannikov · A.V. Nefiodov · A.Yu. Boytsov · A.Yu. Ramzdorf · V.I. Stegailov · S.I. Tyutyunnikov · A.A. Levin

   We discuss recent experiments performed with an upgraded version of the main magnetic focus ion source (MaMFIS) at the Joint Institute for Nuclear Research (JINR) in Dubna. The device operates in the range of electron beam energies extended up to $40$ keV. The achieved electron current densities are of the order of $10$ kA/cm${}^2$. This assessment is consistent both with the very short ionization time and with the utmost ionization degree of the produced highly charged ions. Due to its high efficiency, the MaMFIS technology is especially promising for ionization of short-lived radionuclides and heavy elements. A new scheme for charge breeding is proposed.

   ↳ physics.atom-phnucl-exphysics.acc-phphysics.plasm-phNucl.Instrum.Meth.B(2021)·0 citations
6. 06*

   Exploring Origins for Correlations between Flow Harmonics and Transverse Momentum in Small Collision Systems (Unambiguous Ambiguity)

   S.H. Lim🇰🇷 · J.L. Nagle🇺🇸

   High statistics data sets from experiments at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC) with small and large collision species have enabled a wealth of new flow measurements, including the event-by-event correlation between observables. One exciting such observable $\rho (v_n^2,[p_T])$ gauges the correlation between the mean transverse momentum of particles in an event and the various flow coefficients ($v_n$) in the same event [1]. Recently it has been proposed that very low multiplicity events may be sensitive to initial-state glasma correlations [2] rather than flow-related dynamics. We find utilizing the IP-JAZMA framework that the color domain explanation for the glasma results are incomplete. We then explore predictions from PYTHIA-8, and the version for including nuclear collisions called PYTHIA-ANGANTYR, which have only non-flow correlations and the AMPT model which has both non-flow and flow-type correlations. We find that PYTHIA-ANGANTYR has non-flow contributions to $\rho (v_n^2,[p_T])$ in p+O, p+Pb, O+O collisions that are positive at low multiplicity and comparable to the glasma correlations. It is striking that in PYTHIA-8 in p+p collisions there is actually a sign-change from positive to negative $\rho (v_n^2,[p_T])$ as a function of multiplicity. The AMPT results match the experimental data general trends in Pb+Pb collisions at the LHC, except at low multiplicity where AMPT has the opposite sign. In p+Pb collisions, AMPT has the opposite sign from experimental data and we explore this within the context of parton geometry. Predictions for p+O, O+O, and Xe+Xe are also presented.

   ↳ nucl-thnucl-exPRC(2021)·22 citations
7. 07*

   Diffractive rho + lepton pair production at an electron-ion collider

   W. Cosyn🇺🇸 · B. Pire🇫🇷

   In high energy electron-ion colliders, a new way to probe nucleon structure becomes available through diffractive reactions, where the incident particle produces a very energetic almost forward particle. QCD describes these reactions as due to the exchange of a Pomeron which may be perturbatively described as a dressed two-gluon state, provided a hard scale allows the factorization of the amplitude in terms of two impact factors convoluted with a Pomeron propagator. We consider here a process where such a description allows to access hadronic structure in terms of the generalized parton distributions, namely the electroproduction of a forward $\rho$ meson and a timelike deeply virtual photon, separated by a large rapidity gap. We explore the dependence of the cross section on the kinematic variables and study the dependence on the non-perturbative inputs (generalized parton distributions, distribution amplitude). Our leading order studies show the cross section is mainly sensitive to the GPD model input, but the small size of the cross sections could prohibit straightforward analysis of this process at planned facilities.

   ↳ hep-phnucl-exnucl-thPRD(2021)·12 citations
8. 08*

   On the analysis of signal peaks in pulse-height spectra

   Cade Rodgers🇺🇸 · Christian Iliadis🇺🇸

   The estimation of the signal location and intensity of a peak in a pulse height spectrum is important for x-ray and $\gamma$-ray spectroscopy, charged-particle spectrometry, liquid chromatography, and many other subfields. However, both the "centroid" and "signal intensity" of a peak in a pulse-height spectrum are ill-defined quantities and different methods of analysis will yield different numerical results. Here, we apply three methods of analysis. Method A is based on simple count summation and is likely the technique most frequently applied in practice. The analysis is straightforward and fast, and does not involve any statistical modeling. We find that it provides reliable results only for high signal-to-noise data, but has severe limitations in all other cases. Method B employs a Bayesian model to extract signal counts and centroid from the measured total and background counts. The resulting values are derived from the respective posteriors and, therefore, have a rigorous statistical meaning. The method makes no assumptions about the peak shape. It yields reliable and relatively small centroid uncertainties. However, it provides relatively large signal count uncertainties. Method C makes a strong assumption regarding the peak shape by fitting a Gaussian function to the data. The fit is based again on a Bayesian model. Although Method C requires careful consideration of the Gaussian width (usually given by the detector resolution) used in the fitting, it provides reliable values and relatively small uncertainties both for the signal counts and the centroid.

   ↳ physics.data-annucl-exNucl.Instrum.Meth.A(2021)·5 citations
9. 09*

   Proton-induced activation cross sections in the energy range below 1 GeV

   I. V. Moskalenko🇺🇸 · A. A. Andrianov🇷🇺 · A. V. Bytenko🇷🇺 · T. A. Frolova🇷🇺 · R. S. Khalikov🇷🇺 · A. Yu. Konobeev🇩🇪 · Yu. A. Korovin🇷🇺 · T. V. Kulevoy🇷🇺 · I. S. Kuptsov🇷🇺 · K. V. Pavlov🇷🇺 · A. Yu. Stankovskiy🇧🇪 · E. M. Syresin🇷🇺 · Yu. E. Titarenko🇷🇺 · V. D. Vu🇷🇺

   (Abridged) Modern studies and industrial applications related to the design, radiation protection, and reliability of nuclear facilities, medical applications, as well as space research and exploration are relying on extensive simulations and modeling. Computer codes realizing semi-classical and quantum molecular dynamics (QMD) approaches are often employed to make up for the lack of accelerator data on many nuclear reactions at intermediate and high energies (>10s of MeV/n) and are in high demand. This contribution focuses on the methodology of generating reliable proton-induced cross sections in the energy range below 1 GeV. We developed a problem-oriented computer framework based on MCNPX and CASCADE/INPE codes to calculate activation cross section data at intermediate and high energies. Goodness of the fits of nucleon-nucleus interaction models to the existing data is evaluated based on elaborated algorithms. The method is based on the analysis of a large set of data and calculated cross sections for different targets and residual nuclei in a wide range of proton energies using numerous criteria. In practice, this could be done by tuning the model parameters and algorithms to fit required experimental data subset, or through achieving unification and consistency of fundamental parameters for all considered reactions. The presented framework is pursuing the latter approach. We use proton-induced reactions on Si and Fe nuclei to illustrate the application of the developed multi-criteria algorithm, where we use all data below 1 GeV available from the EXFOR data library and the IAEA CRP "Benchmark of Spallation Models." We show that the analysis of the predictive power of various intermediate and high-energy models based on the multi-criteria algorithm allows more sophisticated selection of appropriate models in a given energy range and residual nuclei domain.

   ↳ astro-ph.HEnucl-exnucl-th0 citations
10. 10*

    Estimation of Impact Parameter and Transverse Spherocity in heavy-ion collisions at the LHC energies using Machine Learning

    Neelkamal Mallick🇮🇳 · Sushanta Tripathy🇮🇹 · Aditya Nath Mishra🇭🇺 · Suman Deb🇮🇳 · Raghunath Sahoo🇮🇳

    Recently, machine learning (ML) techniques have led to a range of numerous developments in the field of nuclear and high-energy physics. In heavy-ion collisions, the impact parameter of a collision is one of the crucial observables which has a significant impact on the final state particle production. However, calculation of such a quantity is nearly impossible in experiments as the length scale ranges in the level of a few fermi. In this work, we implement the ML-based regression technique via Boosted Decision Tree (BDT) to obtain a prediction of impact parameter in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV using A Multi-Phase Transport (AMPT) model. In addition, we predict an event shape observable, transverse spherocity in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 and 5.02 TeV using AMPT and PYTHIA8 based on Angantyr model. After a successful implementation in small collision systems, the use of transverse spherocity in heavy-ion collisions has potential to reveal new results from heavy-ion collisions where the production of a QGP medium is already established. We predict the centrality dependent spherocity distributions from the training of minimum bias simulated data and it was found that the predictions from BDT based ML technique match with true simulated data. In the absence of experimental measurements, we propose to implement Machine learning based regression technique to obtain transverse spherocity from the known final state observables in heavy-ion collisions.

    ↳ hep-phhep-exnucl-exnucl-thPRD(2021)·37 citations
11. 11*

    Searching for axionlike particles with low masses in $pPb$ and $PbPb$ collisions

    V. P. Goncalves🇧🇷 · D. E. Martins🇧🇷 · M. S. Rangel🇧🇷

    The production of axionlike particles (ALPs) with small masses in ultraperipheral $Pb-p$ and $Pb-Pb$ collisions at the LHC is investigated. The cross section and kinematical distributions associated to the diphoton final state produced in the $\gamma \gamma \to a\to \gamma \gamma$ subprocesses are estimated considering a realistic set of kinematical cuts. A detailed analysis of the backgrounds is performed and the expected sensitivity to the ALP production is derived. Our results demonstrate that a future experimental analysis of the exclusive diphoton production for the forward rapidities probed by the LHCb detector can improve the existing exclusion limits on the ALP - photon coupling in the mass range 2 GeV $\le m_a\le$ 5 GeV.

    ↳ hep-phhep-exnucl-exnucl-thEPJC(2021)·23 citations
12. 12*

    Opportunities of OO and $p$O collisions at the LHC

    Jasmine Brewer🇨🇭 · Aleksas Mazeliauskas🇨🇭 · Wilke van der Schee🇨🇭

    This is the summary document of the virtual workshop "Opportunities of OO and $p$O collisions at the LHC", which took place Feb 4-10, 2021. We briefly review the presented perspectives on the physics opportunities of oxygen--oxygen and proton--oxygen collisions. The full workshop program and the recordings are available at cern.ch/OppOatLHC.

    ↳ hep-phastro-ph.HEhep-exnucl-ex+1124 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.