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Title: Time-of-flight mass measurements for nuclear processes in neutron star crusts

The location of electron capture heat sources in the crust of accreting neutron stars depends on the masses of extremely neutron-rich nuclei. We present first results from a new implementation of the time-of-flight technique to measure nuclear masses of rare isotopes at the National Supercon- ducting Cyclotron Laboratory. The masses of 16 neutron-rich nuclei in the Sc Ni element range were determined simultaneously, improving the accuracy compared to previous data in 12 cases. The masses of 61V, 63Cr, 66Mn, and 74Ni were measured for the first time with mass excesses of 30.510(890) MeV, 35.280(650) MeV, 36.900(790) MeV, and 49.210(990) MeV, respectively. With the measurement of the 66Mn mass, the location of the two dominant heat sources in the outer crust of accreting neutron stars, which exhibit so called superbursts, is now experimentally constrained. We find that the location of the 66Fe 66Mn electron capture transition occurs sig- nificantly closer to the surface than previously assumed because our new experimental Q-value is 2.1 MeV smaller than predicted by the FRDM mass model. The results also provide new insights into the structure of neutron-rich nuclei around N = 40.
Authors:
 [1] ;  [2] ;  [3] ;  [1] ;  [1] ;  [4] ;  [1] ;  [3] ;  [1] ;  [1] ;  [1] ;  [1] ;  [5] ;  [6] ;  [1] ;  [7] ;  [1] ;  [1] ;  [1] ;  [6] more »;  [8] ;  [3] ;  [7] ;  [4] « less
  1. National Superconducting Cyclotron Laboratory (NSCL)
  2. Louisiana State University
  3. Michigan State University, East Lansing
  4. University of Notre Dame, IN
  5. Indian Institute of Technology, Kanpur
  6. ORNL
  7. Los Alamos National Laboratory (LANL)
  8. Ohio State University
Publication Date:
OSTI Identifier:
1034370
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review Letters; Journal Volume: 107; Journal Issue: 17
Research Org:
Oak Ridge National Laboratory (ORNL)
Sponsoring Org:
SC USDOE - Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; ACCURACY; ELECTRON CAPTURE; HEAT SOURCES; MASS; MEV RANGE 10-100; NEUTRON STARS; NEUTRON-RICH ISOTOPES; NUCLEI; Q-VALUE; TIME-OF-FLIGHT METHOD