Wed·Apr 15, 2020Wednesday·April 15, 2020

1. 01*

   Scission configuration of ${}^{239}$U from yields and kinetic information of fission fragments

   D. Ramos🇫🇷 · M. Caamano🇪🇸 · A. Lemasson🇫🇷 · M. Rejmund🇫🇷 · L. Audouin🇫🇷 · H. Alvarez-Pol🇪🇸 · J.D. Frankland🇫🇷 · B. Fernandez-Dominguez🇪🇸 · E. Galiana-Baldo🇪🇸 · J. Piot🇫🇷 · D. Ackermann🇫🇷 · S. Biswas🇫🇷 and 16 other authors

   The simultaneous measurement of the isotopic fission-fragment yields and fission-fragment velocities of ${}^{239}$U has been performed for the first time. The ${}^{239}$U fissioning system was produced in one-neutron transfer reactions between a ${}^{238}$U beam at 5.88 MeV/nucleon and a ${}^9$Be target. The combination of inverse kinematics at low energy and the use of the VAMOS++ spectrometer at the GANIL facility allows the isotopic identification of the full fission-fragment distribution and their velocity in the reference frame of the fissioning system. The proton and neutron content of the fragments at scission, their total kinetic and total excitation energy, as well as the neutron multiplicity were determined. Information from the scission point configuration is obtained from these observables and the correlation between them. The role of the octupole-deformed proton and neutron shells in the fission-fragment production is discussed.

   nucl-exnucl-thPRC(2020)·16 citations
2. 02*

   Study of $\Delta$ excitations in medium-mass nuclei with peripheral heavy ion charge-exchange reactions

   J. L. Rodriguez-Sanchez🇪🇸 · J. Benlliure🇪🇸 · I. Vidaña🇮🇹 · H. Lenske🇩🇪 · C. Scheidenberger🇩🇪 · J. Vargas🇪🇸 · H. Alvarez-Pol🇪🇸 · Y. Ayyad🇪🇸 · J. Atkinson🇩🇪 · T. Aumann🇩🇪 · S. Beceiro-Novo🇪🇸 · K. Boretzky🇩🇪 and 17 other authors

   Isobaric single charge-exchange reactions, changing nuclear charges by one unit but leaving the mass partitions unaffected, have been for the first time investigated by peripheral collisions of ${}^{112}$Sn ions accelerated up to 1\textit{A} GeV at the GSI facilities. The high-resolving power of the FRS spectrometer allows us to obtain $(p,n)$-type isobaric charge-exchange cross sections with an uncertainty of $3.5\%$ and to separate quasi-elastic and inelastic components in the missing-energy spectra of the ejectiles. The inelastic component is associated to the excitation of the $\Delta$(1232) isobar resonance and the emission of pions in s-wave both in the target and projectile nucleus, while the quasi-elastic contribution is associated to the nuclear spin-isospin response of nucleon-hole excitations. An apparent shift of the $\Delta$-resonance peak of $\sim$63 MeV is observed when comparing the missing-energy spectra obtained from the measurements with proton and carbon targets. A detailed analysis, performed with a theoretical model for the reactions, indicates that this observation can be simply interpreted as a change in the relative magnitude between the contribution of the excitation of the resonance in the target and in the projectile.

   nucl-exnucl-thPLB(2020)·18 citations
3. 03*

   HPRL -- International cooperation to identify and monitor priority nuclear data needs for nuclear applications

   E. Dupont🇫🇷 · M. Bossant🇫🇷 · R. Capote🇦🇹 · A.D. Carlson🇺🇸 · Y. Danon🇺🇸 · M. Fleming🇫🇷 · Z. Ge🇨🇳 · H. Harada🇯🇵 · O. Iwamoto🇯🇵 · N. Iwamoto🇯🇵 · A. Kimura🇯🇵 · A.J. Koning🇦🇹 and 12 other authors

   The OECD-NEA High Priority Request List (HPRL) is a point of reference to guide and stimulate the improvement of nuclear data for nuclear energy and other applications, and a tool to bridge the gap between data users and producers. The HPRL is application-driven and the requests are submitted by nuclear data users or representatives of the user's communities. A panel of international experts reviews and monitors the requests in the framework of an Expert Group mandated by the NEA Nuclear Science Committee Working Party on International Nuclear Data Evaluation Cooperation (WPEC). After approval, individual requests are classified to three categories: high priority requests, general requests, and special purpose requests (e.g., dosimetry, standards). The HPRL is hosted by the NEA in the form of a relational database publicly available on the web. This paper provides an overview of HPRL entries, status and outlook. Examples of requests successfully completed are given and new requests are described with emphasis on updated nuclear data needs in the fields of nuclear energy, neutron standards and dosimetry.

   nucl-exEPJ Web Conf.(2020)·20 citations
4. 04*

   Development of ultra-pure NaI(Tl) detectors for the COSINE-200 experiment

   B.J. Park🇰🇷 · J.J. Choe🇰🇷 · J.S. Choi🇰🇷 · O. Gileva🇰🇷 · C. Ha🇰🇷 · A. Iltis🇫🇷 · E.J. Jeon🇰🇷 · D.Y. Kim · K.W. Kim · S.K. Kim · Y.D. Kim · Y.J. Ko🇰🇷 and 8 other authors

   The annual modulation signal observed by the DAMA experiment is a long-standing question in the community of dark matter direct detection. This necessitates an independent verification of its existence using the same detection technique. The COSINE-100 experiment has been operating with 106~kg of low-background NaI(Tl) detectors providing interesting checks on the DAMA signal. However, due to higher backgrounds in the NaI(Tl) crystals used in COSINE-100 relative to those used for DAMA, it was difficult to reach final conclusions. Since the start of COSINE-100 data taking in 2016, we also have initiated a program to develop ultra-pure NaI(Tl) crystals for COSINE-200, the next phase of the experiment. The program includes efforts of raw powder purification, ultra-pure NaI(Tl) crystal growth, and detector assembly techniques. After extensive research and development of NaI(Tl) crystal growth, we have successfully grown a few small-size (0.61$-$0.78 kg) thallium-doped crystals with high radio-purity. A high light yield has been achieved by improvements of our detector assembly technique. Here we report the ultra-pure NaI(Tl) detector developments at the Institute for Basic Science, Korea. The technique developed here will be applied to the production of NaI(Tl) detectors for the COSINE-200 experiment.

   ↳ physics.ins-detastro-ph.IMhep-exnucl-exEPJC(2020)·47 citations
5. 05*

   Discrimination of electronic recoils from nuclear recoils in two-phase xenon time projection chambers

   LUX Collaboration: D. S. Akerib🇺🇸 · S. Alsum🇺🇸 · H. M. Araújo🇬🇧 · X. Bai🇺🇸 · J. Balajthy🇺🇸 · A. Baxter🇬🇧 · E. P. Bernard🇺🇸 · A. Bernstein🇺🇸 · T. P. Biesiadzinski🇺🇸 · E.M. Boulton🇺🇸 · B. Boxer🇬🇧 · P. Brás🇵🇹 and 84 other authors

   We present a comprehensive analysis of electronic recoil vs. nuclear recoil discrimination in liquid/gas xenon time projection chambers, using calibration data from the 2013 and 2014-16 runs of the Large Underground Xenon (LUX) experiment. We observe strong charge-to-light discrimination enhancement with increased event energy. For events with S1 = 120 detected photons, i.e. equivalent to a nuclear recoil energy of $\sim$100 keV, we observe an electronic recoil background acceptance of $<10^{-5}$ at a nuclear recoil signal acceptance of 50%. We also observe modest electric field dependence of the discrimination power, which peaks at a field of around 300 V/cm over the range of fields explored in this study (50-500 V/cm). In the WIMP search region of S1 = 1-80 phd, the minimum electronic recoil leakage we observe is $(7.3\pm 0.6)\times 10^{-4}$, which is obtained for a drift field of 240-290 V/cm. Pulse shape discrimination is utilized to improve our results, and we find that, at low energies and low fields, there is an additional reduction in background leakage by a factor of up to 3. We develop an empirical model for recombination fluctuations which, when used alongside the Noble Element Scintillation Technique (NEST) simulation package, correctly reproduces the skewness of the electronic recoil data. We use this updated simulation to study the width of the electronic recoil band, finding that its dominant contribution comes from electron-ion recombination fluctuations, followed in magnitude of contribution by fluctuations in the S1 signal, fluctuations in the S2 signal, and fluctuations in the total number of quanta produced for a given energy deposition.

   ↳ physics.ins-dethep-exnucl-exPRD(2020)·54 citations
6. 06*

   Neutrino Long-Baseline Experiments and Nuclear Physics

   Ulrich Mosel🇩🇪

   The extraction of neutrino properties from long-baseline experiments such as T2K, NOvA and DUNE requires a good description of the initial neutrino-nucleon interaction. Since the targets in all running or planned experiments are nuclei (C12, O16, Ar40) the extraction also requires a reliable description of nuclear structure and nuclear reactions that become essential during the final state interactions of the neutrino-nucleus reactions. This article presents a short introduction into these problems for a non-expert readership. It also stresses that a generator that implements state-of-the-art methods of nuclear structure and reactions is still needed for these state-of-the-art experiments.

   ↳ nucl-thhep-exhep-phnucl-exNucl.Phys.News(2019)·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.