Jutta Escher

Bio: Jutta Escher is an academic researcher from Lawrence Livermore National Laboratory. The author has contributed to research in topics: Neutron capture & Nuclear reaction. The author has an hindex of 20, co-authored 124 publications receiving 1369 citations. Previous affiliations of Jutta Escher include TRIUMF & Louisiana State University.

Compound-nuclear reaction cross sections from surrogate measurements

Abstract: Nuclear reaction cross sections are important for a variety of applications in the areas of astrophysics, nuclear energy, and national security. When these cross sections cannot be measured directly or predicted reliably, it becomes necessary to develop indirect methods for determining the relevant reaction rates. The surrogate nuclear reactions approach is such an indirect method. First used in the 1970s for estimating ðn; fÞ cross sections, the method has recently been recognized as a potentially powerful tool for a wide range of applications that involve compound-nuclear reactions. The method is expected to become an important focus of inverse-kinematics experiments at rareisotope facilities. The present paper reviews the current status of the surrogate approach. Experimental techniques employed and theoretical descriptions of the reaction mechanisms involved are presented and representative cross section measurements are discussed.

Determining (n,f) cross sections for actinide nuclei indirectly: Examination of the surrogate ratio method

Abstract: The validity of the Surrogate Ratio method for determining (n,f) cross sections for actinide nuclei is examined. This method relates the ratio of two compound-nucleus reaction cross sections to a ratio of coincidence events from two measurements in which the same compound nuclei are formed via a direct reaction. With certain assumptions, the method allows one of the cross sections to be inferred if the other is known. We develop a nuclear reaction-model simulation to investigate whether the assumptions underlying the Ratio approach are valid and employ these simulations to assess whether the cross sections obtained indirectly by applying a Ratio analysis agree with the expected results. In particular, we simulate Surrogate experiments that allow us to determine fission cross sections for selected actinide nuclei. The nuclei studied, {sup 233}U and {sup 235}U, are very similar to those considered in recent Surrogate experiments. We find that in favorable cases the Ratio method provides useful estimates of the desired cross sections, and we discuss some of the limitations of the approach.

Toward a complete theory for predicting inclusive deuteron breakup away from stability

Abstract: We present an account of the current status of the theoretical treatment of inclusive (d, p) reactions in the breakup-fusion formalism, pointing to some applications and making the connection with current experimental capabilities Three independent implementations of the reaction formalism have been recently developed, making use of different numerical strategies The codes also originally relied on two different but equivalent representations, namely the prior (Udagawa-Tamura, UT) and the post (Ichimura-Austern-Vincent, IAV) representations The different implementations have been benchmarked for the first time, and then applied to the Ca isotopic chain The neutron-Ca propagator is described in the Dispersive Optical Model (DOM) framework, and the interplay between elastic breakup (EB) and non-elastic breakup (NEB) is studied for three Ca isotopes at two different bombarding energies The accuracy of the description of different reaction observables is assessed by comparing with experimental data of (d, p) on 40,48Ca We discuss the predictions of the model for the extreme case of an isotope (60Ca) currently unavailable experimentally, though possibly available in future facilities (nominally within production reach at FRIB) We explore the use of (d, p) reactions as surrogates for $(n,\gamma )$ processes, by using the formalism to describe the compound nucleus formation in a $(d,p\gamma )$ reaction as a function of excitation energy, spin, and parity The subsequent decay is then computed within a Hauser-Feshbach formalism Comparisons between the $(d,p\gamma )$ and $(n,\gamma )$ induced gamma decay spectra are discussed to inform efforts to infer neutron captures from $(d,p\gamma )$ reactions Finally, we identify areas of opportunity for future developments, and discuss a possible path toward a predictive reaction theory

Deducing the 237U(n,f) cross-section using the Surrogate Ratio Method

Abstract: We have deduced the cross section for $^{237}\mathrm{U}$($n,f$) over an equivalent neutron energy range from 0 to 20 MeV using the surrogate ratio method. A 55 MeV $^{4}\mathrm{He}$ beam from the 88 inch cyclotron at Lawrence Berkeley National Laboratory was used to induce fission in the following reactions: $^{238}\mathrm{U}$$(\ensuremath{\alpha},{\ensuremath{\alpha}}^{\ensuremath{'}}f)$ and $^{236}\mathrm{U}$$(\ensuremath{\alpha},{\ensuremath{\alpha}}^{\ensuremath{'}}f)$. The $^{238}\mathrm{U}$ reaction was a surrogate for $^{237}\mathrm{U}$$(n,f)$, and the $^{236}\mathrm{U}$ reaction was used as a surrogate for $^{235}\mathrm{U}$$(n,f)$. Scattered \ensuremath{\alpha} particles were detected in a fully depleted segmented silicon telescope array over an angle range of ${35}^{\ifmmode^\circ\else\textdegree\fi{}}$ to ${60}^{\ifmmode^\circ\else\textdegree\fi{}}$ with respect to the beam axis. The fission fragments were detected in a third independent silicon detector located at backward angles between ${106}^{\ifmmode^\circ\else\textdegree\fi{}}$ and ${131}^{\ifmmode^\circ\else\textdegree\fi{}}$.

Fermion realization of the nuclear Sp(6,R) model

Abstract: A fermion realization of the nuclear Sp(6,R) model, which complements the traditional bosonic representation, is developed. A recursive process is presented in which symplectic matrix elements of arbitrary one-body fermion operators between states of excitation Nℏω and N′ℏω in the same or in different symplectic bands are related back to valence shell matrix elements, which can be evaluated by standard shell model techniques. Matrix elements so determined may be used to calculate observables such as electron scattering form factors which carry detailed structural information on nuclear wave functions.

Multi-messenger Observations of a Binary Neutron Star

Abstract: This program was supported by the the Kavli Foundation, Danish National Research Foundation, the Niels Bohr International Academy, and the DARK Cosmology Centre. The UCSC group is supported in part by NSF grant AST-1518052, the Gordon & Betty Moore Foundation, the Heising-Simons Foundation, generous donations from many individuals through a UCSC Giving Day grant, and from fellowships from the Alfred P. Sloan Foundation (R.J.F.), the David and Lucile Packard Foundation (R.J.F. and E.R.) and the Niels Bohr Professorship from the DNRF (E.R.). AMB acknowledges support from a UCMEXUS-CONACYT Doctoral Fellowship. Support for this work was provided by NASA through Hubble Fellowship grants HST-HF-51348.001 (B.J.S.) and HST-HF-51373.001 (M.R.D.) awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555. This paper includes data gathered with the 1 meter Swope and 6.5 meter Magellan Telescopes located at Las Campanas Observatory, Chile.r (AGILE) The AGILE Team thanks the ASI management, the technical staff at the ASI Malindi ground station, the technical support team at the ASI Space Science Data Center, and the Fucino AGILE Mission Operation Center. AGILE is an ASI space mission developed with programmatic support by INAF and INFN. We acknowledge partial support through the ASI grant No. I/028/12/2. We also thank INAF, Italian Institute of Astrophysics, and ASI, Italian Space Agency.r (ANTARES) The ANTARES Collaboration acknowledges the financial support of: Centre National de la Recherche Scientifique (CNRS), Commissariat a l'energie atomique et aux energies alternatives (CEA), Commission Europeenne (FEDER fund and Marie Curie Program), Institut Universitaire de France (IUF), IdEx program and UnivEarthS Labex program at Sorbonne Paris Cite (ANR-10-LABX-0023 and ANR-11-IDEX-0005-02), Labex OCEVU (ANR-11-LABX-0060) and the A*MIDEX project (ANR-11-IDEX-0001-02), Region Ile-de-France (DIM-ACAV), Region Alsace (contrat CPER), Region Provence-Alpes-Cite d'Azur, Departement du Var and Ville de La Seyne-sur-Mer, France; Bundesministerium fur Bildung und Forschung (BMBF), Germany; Istituto Nazionale di Fisica Nucleare (INFN), Italy; Nederlandse organisatie voor Wetenschappelijk Onderzoek (NWO), the Netherlands; Council of the President of the Russian Federation for young scientists and leading scientific schools supporting grants, Russia; National Authority for Scientific Research (ANCS), Romania;...

Reviews of Modern Physics

Abstract: Associate DIETRICH BELITZ, University of Oregon Editors: Condensed Matter Physics (Theoretical) J. IGNACIO CIRAC, Max-Planck-Institut für Quantenoptik Quantum Information RAYMOND E. GOLDSTEIN, University of Cambridge Biological Physics ARTHUR F. HEBARD, University of Florida Condensed Matter Physics (Experimental) RANDALL D. KAMIEN, University of Pennsylvania Soft Condensed Matter DANIEL KLEPPNER, Massachusetts Institute of Technology Atomic, Molecular, and Optical Physics (Experimental) PAUL G. LANGACKER, Institute for Advanced Study, Princeton University Particle Physics (Theoretical) VERA LÜTH, Stanford University Particle Physics (Experimental) DAVID D. MEYERHOFER, University of Rochester Physics of Plasmas and Matter at High-Energy Density WITOLD NAZAREWICZ, University of Tennessee, Oak Ridge National Laboratory Nuclear Physics JOHN H. SCHWARZ, California Institute of Technology Mathematical Physics FRIEDRICH-KARL THIELEMANN, Universität Basel Astrophysics Senior Assistant Editor: DEBBIE BRODBAR, APS Editorial Office American Physical Society

Annual Review of Nuclear and Particle Science

Abstract: The contents of this review reflect some of the shifts of emphasis that are occurring among the fields of astrophysics, nuclear physics, and elementary particle physics. Particle physics has made great advances in the unification of the fundamental forces of nature. Discussions and planning for a next big step in accelerator-colliders are presented. The technology of superconducting magnet systems as well as the fundamental physical principles of particle accelerators are discussed. Also presented are: high-resolution electronic particle detectors; nuclear physics changes such as pion interactions within nuclei; discussion of future relativistic heavy-ion colliders; the role of rotational degrees of freedom in heavy-ion collisions at low and moderate energies; hyperon beta decays; and the analysis of materials via nuclear reaction techniques. Neutrinos, their interactions and possible masses, have an important bearing on cosmology and the matter density of the universe in addition to their inherent interest in the microscopic world and this is also examined.