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Title: Annual Continuation And Progress Report For Low-Energy Nuclear Physics Research At Lawrence Livermore National Laboratory

(I)In this project, the Beta-­decay Paul Trap, an open-­geometry RFQ ion trap that can be instrumented with sophisticated radiation detection arrays, is used for precision β-­decay studies. Measurements of β-­decay angular correlations, which are sensitive to exotic particles and other phenomena beyond the Standard Model (SM) of particle physics that may occur at the TeV-­energy scale, are being performed by taking advantage of the favorable properties of the mirror 8Li and 8B β± decays and the benefits afforded by using trapped ions. By detecting the β and two α particles emitted in these decays, the complete kinematics can be reconstructed. This allows a simultaneous measurement of the β-­n, β-­n-­α, and β-α correlations and a determination of the neutrino energy and momentum event by event. In addition, the 8B neutrino spectrum, of great interest in solar neutrino oscillation studies, can be determined in a new way. Beta-­delayed neutron spectroscopy is also being performed on neutron-­rich isotopes by studying the β-­decay recoil ions that emerge from the trap with high efficiency, good energy resolution, and practically no backgrounds. This novel technique is being used to study isotopes of mass-­number A~130 in the vicinity of the N=82 neutron magic number to help understandmore » the rapid neutron-­capture process (r-­process) that creates many of the heavy isotopes observed in the cosmos. (II)A year-long CHICO2 campaign at ANL/ATLAS together with GRETINA included a total of 10 experiments, seven with the radioactive beams from CARIBU and three with stable beams, with 82 researchers involved from 27 institutions worldwide. CHICO2 performed flawlessly during this long campaign with achieved position resolution matching to that of GRETINA, which greatly enhances the sensitivity in the study of nuclear γ-­ray spectroscopy. This can be demonstrated in our results on 144Ba and 146Ba where the octupole deformation is evident from the measured B(E3; 3-→0+) strengths that significantly greater than the theoretical predictions. We anticipate that CHICO2 will continue to be a viable charged-­particle detector for the research need of the low-­energy nuclear physics community.« less
Authors:
 [1] ;  [1]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Publication Date:
OSTI Identifier:
1239223
Report Number(s):
LLNL--TR-678634
TRN: US1600561
DOE Contract Number:
AC52-07NA27344
Resource Type:
Technical Report
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; 46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; RESEARCH PROGRAMS; BETA DECAY; BETA-DELAYED NEUTRONS; LAWRENCE LIVERMORE NATIONAL LABORATORY; BORON 8; ANGULAR CORRELATION; ALPHA PARTICLES; BETA PARTICLES; ENERGY RESOLUTION; NUCLEAR PHYSICS; BARIUM 144; BARIUM 146; INDIUM 130; LITHIUM 8; NEUTRON-RICH ISOTOPES; PROGRESS REPORT; ANL; R PROCESS; IONS; TRAPS; OCTUPOLES; NEUTRON SPECTROSCOPY; ACCURACY; NUCLEAR DEFORMATION; EFFICIENCY; MIRROR NUCLEI; RECOILS; SENSITIVITY; SPECTRA; TRAPPING; E3-TRANSITIONS; BRANCHING RATIO