Fri·Jun 12, 2015Friday·June 12, 2015

1. 01*

   Ab initio alpha-alpha scattering

   Serdar Elhatisari🇩🇪 · Dean Lee🇺🇸 · Gautam Rupak🇺🇸 · Evgeny Epelbaum🇩🇪 · Hermann Krebs🇩🇪 · Timo A. Lähde🇩🇪 · Thomas Luu🇩🇪 · Ulf-G. Meißner🇩🇪

   Processes involving alpha particles and alpha-like nuclei comprise a major part of stellar nucleosynthesis and hypothesized mechanisms for thermonuclear supernovae. In an effort towards understanding alpha processes from first principles, we describe in this letter the first ab initio calculation of alpha-alpha scattering. We use lattice effective field theory to describe the low-energy interactions of nucleons and apply a technique called the adiabatic projection method to reduce the eight-body system to an effective two-cluster system. We find good agreement between lattice results and experimental phase shifts for S-wave and D-wave scattering. The computational scaling with particle number suggests that alpha processes involving heavier nuclei are also within reach in the near future.

   ↳ nucl-thcond-mat.quant-gashep-latnucl-exNature(2015)·197 citations
2. 02*

   Background Radiation Measurements at High Power Research Reactors

   J. Ashenfelter🇺🇸 · B. Balantekin🇺🇸 · C. X. Baldenegro🇺🇸 · H. R. Band🇺🇸 · G. Barclay🇺🇸 · C. D. Bass🇺🇸 · D. Berish🇺🇸 · N. S. Bowden🇺🇸 · C. D. Bryan🇺🇸 · J. J. Cherwinka🇺🇸 · R. Chu🇺🇸 · T. Classen🇺🇸 and 49 other authors

   Research reactors host a wide range of activities that make use of the intense neutron fluxes generated at these facilities. Recent interest in performing measurements with relatively low event rates, e.g. reactor antineutrino detection, at these facilities necessitates a detailed understanding of background radiation fields. Both reactor-correlated and naturally occurring background sources are potentially important, even at levels well below those of importance for typical activities. Here we describe a comprehensive series of background assessments at three high-power research reactors, including $\gamma$-ray, neutron, and muon measurements. For each facility we describe the characteristics and identify the sources of the background fields encountered. The general understanding gained of background production mechanisms and their relationship to facility features will prove valuable for the planning of any sensitive measurement conducted therein.

   ↳ physics.ins-dethep-exnucl-exNucl.Instrum.Meth.A(2016)·47 citations
3. 03*

   Research and Development of Commercially Manufactured Large GEM Foils

   M. Posik🇺🇸 · B. Surrow🇺🇸

   With future experiments proposing detectors that utilize very large-area GEM foils, there is a need for commercially available GEM foils. Double-mask etching techniques pose a clear limitation in the maximum size of GEM foils. In contrast, single-mask techniques developed at CERN would allow one to overcome those limitations. However with interest in GEM foils increasing and CERN being the only main distributor, keeping up with the demand for GEM foils will be difficult. Thus the commercialization of GEMs has been established by Tech-Etch of Plymouth, MA, USA using single-mask techniques. We report on the electrical and geometrical properties, along with the inner and outer hole diameter size uniformity of 10 $\times$ 10 cm${}^2$ and 40$\times$40 cm${}^2$ GEM foils. The Tech-Etch foils were found to have excellent electrical properties. The measured mean optical properties were found to reflect the desired parameters and are consistent with those measured in double-mask GEM foils, and show good hole diameter uniformity over the active area. These foils are well suited for future applications in nuclear and particle physics where tracking devices are needed.

   ↳ physics.ins-detnucl-exNucl.Instrum.Meth.A(2015)·10 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.