Tue·Nov 3, 2020Tuesday·November 3, 2020

1. 01*

   Ruling out color transparency in quasi-elastic ${}^{12}$C(e,e'p) up to $Q^2$ of 14.2 (GeV/c)${}^2$

   D. Bhetuwal🇺🇸 · J. Matter🇺🇸 · H. Szumila-Vance🇺🇸 · M. L. Kabir🇺🇸 · D. Dutta🇺🇸 · R. Ent🇺🇸 · D. Abrams🇺🇸 · Z. Ahmed🇨🇦 · B. Aljawrneh🇺🇸 · S. Alsalmi🇺🇸 · R. Ambrose🇨🇦 · D. Androic🇭🇷 and 78 other authors

   Quasielastic ${}^{12}$C$(e,e^{\prime }p)$ scattering was measured at space-like 4-momentum transfer squared $Q^2$~=~8, 9.4, 11.4, and 14.2 (GeV/c)${}^2$, the highest ever achieved to date. Nuclear transparency for this reaction was extracted by comparing the measured yield to that expected from a plane-wave impulse approximation calculation without any final state interactions. The measured transparency was consistent with no $Q^2$ dependence, up to proton momenta of 8.5~GeV/c, ruling out the quantum chromodynamics effect of color transparency at the measured $Q^2$ scales in exclusive $(e,e^{\prime }p)$ reactions. These results impose strict constraints on models of color transparency for protons.

   nucl-exhep-exnucl-thPRL(2021)·50 citations
2. 02*

   A novel approach for extracting model-independent nuclear level densities far from stability

   D. Mücher🇨🇦 · A. Spyrou · M. Wiedeking🇿🇦 · M. Guttormsen🇳🇴 · A.C. Larsen🇳🇴 · F. Zeiser🇳🇴 · C. Harris · A.L. Richard🇺🇸 · M.K. Smith · A. Görgen🇳🇴 · S. N. Liddick🇺🇸 · S. Siem🇳🇴 and 13 other authors

   The level density of quantum states in statistical mesoscopic systems is a critical input for various fields of physics, including nuclear physics, nuclear astrophysics, atomic physics and their applications. In atomic nuclei, the level density is a fundamental measure of their complex structure at relatively high energies. Here we present the first model-independent measurement of the absolute partial nuclear level density for a short-lived unstable nucleus. For this purpose, we introduce the ``Shape method'' to extract the shape of the $\gamma$-ray strength function. Combining the Shape method with the existing $\beta$-Oslo technique allows the extraction of the nuclear level density without the need for theoretical input. We benchmark the Shape method using results for the stable ${}^{76}$Ge nucleus, finding an excellent agreement to previous experimental results. We apply the Shape method to new experimental data on the short-lived ${}^{88}$Kr nucleus. Our method opens the door for measurements of the nuclear level density and $\gamma$-ray strength function far away from stability, a pivotal input required to understand the role of exotic nuclei in forming the cosmos.

   nucl-ex3 citations
3. 03*

   Constraints on elastic neutrino nucleus scattering in the fully coherent regime from the CONUS experiment

   H.Bonet🇩🇪 · A.Bonhomme🇩🇪 · C.Buck🇩🇪 · K.Fülber🇩🇪 · J.Hakenmüller🇩🇪 · G.Heusser🇩🇪 · T.Hugle🇩🇪 · M.Lindner🇩🇪 · W.Maneschg🇩🇪 · T.Rink🇩🇪 · H.Strecker🇩🇪 · R.Wink🇩🇪

   We report the best limit on coherent elastic scattering of electron antineutrinos emitted from a nuclear reactor off germanium nuclei. The measurement was performed with the CONUS detectors positioned at 17.1m from the 3.9GWth reactor core of the nuclear power plant in Brokdorf, Germany. The antineutrino energies of less than 10 MeV assure interactions in the fully coherent regime. The analyzed dataset includes 248.7 kgd with the reactor turned on and background data of 58.8 kgd with the reactor off. With a quenching parameter of k = 0.18 for germanium, we determined an upper limit on the number of neutrino events of 85 in the region of interest at 90% confidence level. This new CONUS dataset disfavors quenching parameters above k = 0.27, under the assumption of standard-model-like coherent scattering of the reactor antineutrinos.

   ↳ hep-exnucl-exPRL(2021)·146 citations
4. 04*

   Search for sterile neutrino oscillation using RENO and NEOS data

   (The RENO and NEOS Collaborations) Z. Atif · J. H. Choi · B. Y. Han · C. H. Jang · H. I. Jang · J. S. Jang · E. J. Jeon · S. H. Jeon · K. K. Joo · K. Ju · D. E. Jung · H. J. Kim and 35 other authors

   We present a reactor model independent search for sterile neutrino oscillation using 2\,509\,days of RENO near detector data and 180 days of NEOS data. The reactor related systematic uncertainties are significantly suppressed as both detectors are located at the same reactor complex of Hanbit Nuclear Power Plant. The search is performed by electron antineutrino\,(${\overline{\nu }}_e$) disappearance between six reactors and two detectors with baselines of 294\,m\,(RENO) and 24\,m\,(NEOS). A spectral comparison of the NEOS prompt-energy spectrum with a no-oscillation prediction from the RENO measurement can explore reactor ${\overline{\nu }}_e$ oscillations to sterile neutrino. Based on the comparison, we obtain a 95\% C.L. excluded region of $0.1<|\Delta m_{41}^2|<7$\,eV${}^2$. We also obtain a 68\% C.L. allowed region with the best fit of $|\Delta m_{41}^2|=2.41\pm 0.03$\,eV${}^2$ and ${\sin }^{2}2{\theta }_{14}$=0.08$\pm$0.03 with a p-value of 8.2\%. Comparisons of obtained reactor antineutrino spectra at reactor sources are made among RENO, NEOS, and Daya Bay to find a possible spectral variation.

   ↳ hep-exnucl-exPRD(2022)·75 citations
5. 05*

   An effective field theory approach to fermionic rotational bands in nuclei

   I. K. Alnamlah · E. A. Coello Pérez🇺🇸 · D. R. Phillips🇺🇸

   We extend an effective field theory developed to describe rotational bands in even-even nuclei to the odd-mass case. This organizes Bohr and Mottelson's treatment of a particle coupled to a rotor as a model-independent expansion in powers of the angular velocity of the overall system. We carry out this expansion up to fourth order in the angular velocity and present results for ${}^{99}$Tc, ${}^{159}$Dy, ${}^{167,169}$Er, ${}^{167,169}$Tm, ${}^{183}$W, ${}^{235}$U and ${}^{239}$Pu. In each case, the accuracy and breakdown scale of the effective field theory can be understood based on the single-particle and vibrational energy scales in that nucleus.

   ↳ nucl-thnucl-exPRC(2021)·11 citations
6. 06*

   Decipher the $R_{{\Psi }_m}$ correlator in search for the chiral magnetic effect in relativistic heavy ion collisions

   Yicheng Feng🇺🇸 · Jie Zhao🇺🇸 · Hao-jie Xu🇨🇳 · Fuqiang Wang🇺🇸

   Background: The chiral magnetic effect (CME) is extensively studied in heavy-ion collisions at RHIC and the LHC. An azimuthal correlator called $R_{{\Psi }_m}$ was proposed to measure the CME. By observing the same $R_{{\Psi }_2}$ and $R_{{\Psi }_3}$ (convex) distributions from A Multi-Phase Transport (AMPT) model, by contrasting data and model as well as large and small systems and by event shape engineering (ESE), a recent preprint (arXiv:2006.04251v1) from STAR suggests that the $R_{{\Psi }_m}$ observable is sensitive to the CME signal and relatively insensitive to backgrounds, and their Au+Au data are inconsistent with known background contributions. Purpose: We examine those claims by studying the robustness of the $R_{{\Psi }_m}$ observable using AMPT as well as toy model simulations. We compare $R_{{\Psi }_m}$ to the more widely used $\Delta \gamma$ azimuthal correlator to identify their commonalities and differences. Methods: We use AMPT to simulate Au+Au, p+Au, and d+Au collisions at $\sqrt{s_{NN}}=200\text{ GeV}$, and study the responses of $R_{{\Psi }_m}$ to anisotropic flow backgrounds in the model. We also use a toy model to simulate resonance flow background and input CME signal to investigate their effects in $R_{{\Psi }_2}$. Additionally we use the toy model to perform an ESE analysis to compare to STAR data as well as predict the degree of sensitivity of $R_{{\Psi }_2}$ to isobar collisions with the event statistics taken at RHIC. ...

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

   Beyond the acceptance limit of DRAGON: the case of the ${}^6\mathrm{Li}(\alpha ,\gamma {)}^{10}\mathrm{B}$ reaction

   A. Psaltis · A.A. Chen · D.S. Connolly · B. Davids · G. Gilardy · R. Giri · U Greife · W. Huang · D.A. Hutcheon · J. Karpesky · A. Lennarz · J. Liang and 4 other authors

   Radiative capture reactions play a pivotal role for our understanding of the origin of the elements in the cosmos. Recoil separators provide an effective way to study these reactions, in inverse kinematics, and take advantage of the use of radioactive ion beams. However, a limiting factor in the study of radiative capture reactions in inverse kinematics is the momentum spread of the product nuclei, which can result in an angular spread larger than the geometric acceptance of the separator. The DRAGON facility at TRIUMF is a versatile recoil separator, designed to study radiative capture reactions relevant to astrophysics in the $\mathrm{A}\sim 10-30$ region. In this work we present the first attempt to study with DRAGON a reaction, ${}^6\mathrm{Li}(\alpha ,\gamma {)}^{10}\mathrm{B}$ , for which the recoil angular spread exceeds DRAGON's acceptance. Our result is in good agreement with the literature value, showing that DRAGON can measure resonance strengths of astrophysically important reactions even when not all the recoils enter the separator.

   ↳ physics.ins-detnucl-exNucl.Instrum.Meth.A(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.