Wed·Jun 17, 2015Wednesday·June 17, 2015

1. 01*

   Calibration of Time Of Flight Detectors Using Laser-driven Neutron Source

   S.R. Mirfayzi🇬🇧 · S. Kar🇬🇧 · H. Ahmed🇬🇧 · A.G. Krygier🇺🇸 · A. Green🇬🇧 · A. Alejo🇬🇧 · R. Clarke🇬🇧 · R.R. Freeman🇺🇸 · J. Fuchs🇫🇷 · D. Jung🇬🇧 · A. Kleinschmidt🇩🇪 · J.T. Morrison🇺🇸 and 8 other authors

   Calibration of three scintillators (EJ232Q, BC422Q and EJ410) in a time-of-flight (TOF) arrangement using a laser drive-neutron source is presented. The three plastic scintillator detectors were calibrated with gamma insensitive bubble detector spectrometers, which were absolutely calibrated over a wide range of neutron energies ranging from sub MeV to 20 MeV. A typical set of data obtained simultaneously by the detectors are shown, measuring the neutron spectrum emitted from a petawatt laser irradiated thin foil.

   ↳ physics.ins-detnucl-exRev.Sci.Instrum.(2015)·13 citations
2. 02*

   Systematics of strength function sum rules

   Calvin W. Johnson🇺🇸

   Sum rules provide useful insights into transition strength functions and are often expressed as expectation values of an operator. In this letter I demonstrate that non-energy-weighted transition sum rules have strong secular dependences on the energy of the initial state. Such non-trivial systematics have consequences: the simplification suggested by the generalized Brink-Axel hypothesis, for example, does not hold for most cases, though it weakly holds in at least some cases for electric dipole transitions. Furthermore, I show the systematics can be understood through spectral distribution theory, calculated via traces of operators and of products of operators. Seen through this lens, violation of the generalized Brink-Axel hypothesis is unsurprising: one \textit{expects} sum rules to evolve with excitation energy. Furthermore, to lowest order the slope of the secular evolution can be traced to a component of the Hamiltonian being positive (repulsive) or negative (attractive).

   ↳ nucl-thastro-ph.SRnucl-exPLB(2015)·37 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.