Wed·Oct 12, 2011Wednesday·October 12, 2011

1. 01*

   Project 8: Using Radio Frequencies to Measure the Neutrino Mass

   N. S. Oblath🇺🇸

   It is well known that the neutrino masses affect the shape of the energy spectrum of tritium beta-decay electrons. However, experiments have yet to measure that distortion. The Project 8 experiment proposes to measure the spectral distortion in a novel way: using radio-frequency techniques to detect and measure the energies of the beta-decay electrons. We plan on measuring the radiation created from the cyclotron motion of the electrons in a strong magnetic field. I will report on the status of a prototype that is designed to demonstrate single-electron detection at energies near the tritium endpoint, 18.6 keV. I will also discuss the possibilities for scaling up to a neutrino-mass experiment.

   nucl-exhep-ex1 citation
2. 02*

   Recent Results of Fluctuation and Correlation Studies from the QCD Critical Point Search at RHIC

   Terence J Tarnowsky🇺🇸

   Enhanced fluctuations and correlations have been observed in the phase transitions of many systems. Their appearance at the predicted QCD phase transition (especially near the expected critical point) may provide insight into the nature of the phase transition. Recent results from the QCD Critical Point Search at RHIC will be presented, with a focus on particle ratio ($K/\pi$, $p/\pi$, and $K/p$) fluctuations and their comparison to previous measurements and theoretical predictions.

   nucl-exhep-ph3 citations
3. 03*

   Electromagnetic emission from hot medium measured by the PHENIX experiment at RHIC

   Takao Sakaguchi (for the PHENIX Collaboration)🇺🇸

   Electromagnetic radiation has been of interest in heavy ion collisions because they shed light on early stages of the collisions where hadronic probes do not provide direct information since hadronization and hadronic interactions occur later. The latest results on photon measurement from the PHENIX experiment at RHIC reflect thermodynamic properties of the matter produced in the heavy ion collisions. An unexpectedly large positive elliptic flow measured for direct photons can not be explained by any of the current models.

   nucl-exhep-exnucl-thJ.Phys.Conf.Ser.(2012)·0 citations
4. 04*

   A direct probe of the in-medium pn scattering cross section

   Gao-Chan Yong🇨🇳 · Wei Zuo🇨🇳 · Xun-Chao Zhang🇨🇳

   Hard photon production from neutron-proton bremsstrahlung in intermediate energy heavy-ion reactions is examined as a probe of the in-medium pn scattering cross section within a transport model. Uncertainty of photon production probability pn-pngamma is cancelled out by using the ratio of hard photon spectra R_{12C+12C/p+n}(gamma) from two reactions. The in medium pn scattering cross section is constrained by using the ratio of hard photon production cross sections of proton-induced reactions p+12C and p+2H. A reduction factor sigma_pn^medium/sigma_pn^free of about 0.5 ~ 0.7 around saturation density is obtained by comparing with the existing experimental data.

   ↳ nucl-thnucl-exPLB(2011)·19 citations
5. 05*

   Ionization cross sections for low energy electron transport

   Hee Seo🇰🇷 · Maria Grazia Pia🇮🇹 · Paolo Saracco🇮🇹 · Chan Hyeong Kim🇰🇷

   Two models for the calculation of ionization cross sections by electron impact on atoms, the Binary-Encouter-Bethe and the Deutsch-Maerk models, have been implemented; they are intended to extend and improve Geant4 simulation capabilities in the energy range below 1 keV. The physics features of the implementation of the models are described, and their differences with respect to the original formulations are discussed. Results of the verification with respect to the original theoretical sources and of extensive validation with respect to experimental data are reported. The validation process also concerns the ionization cross sections included in the Evaluated Electron Data Library used by Geant4 for low energy electron transport. Among the three cross section options, the Deutsch-Maerk model is identified as the most accurate at reproducing experimental data over the energy range subject to test.

   ↳ physics.comp-phnucl-exIEEE Trans.Nucl.Sci.(2011)·9 citations
6. 06*

   Validation of proton ionization cross section generators for Monte Carlo particle transport

   Matej Batic🇮🇹 · Maria Grazia Pia🇮🇹 · Paolo Saracco🇮🇹

   Three software systems, ERCS08, ISICS 2011 and Šmit's code, that implement theoretical calculations of inner shell ionization cross sections by proton impact, are validated with respect to experimental data. The accuracy of the cross sections they generate is quantitatively estimated and inter-compared through statistical methods. Updates and extensions of a cross section data library relevant to PIXE simulation with Geant4 are discussed.

   ↳ physics.comp-phnucl-exIEEE Trans.Nucl.Sci.(2011)·4 citations
7. 07*

   Constraints on the large-x d/u ratio from electron-nucleus scattering at x>1

   O. Hen🇮🇱 · A. Accardi🇺🇸 · W. Melnitchouk🇺🇸 · E. Piasetzky🇮🇱

   Recently the ratio of neutron to proton structure functions F_2n/F_2p was extracted from a phenomenological correlation between the strength of the nuclear EMC effect and inclusive electron-nucleus cross section ratios at x>1. Within conventional models of nuclear smearing, this "in-medium correction" (IMC) extraction constrains the size of nuclear effects in the deuteron structure functions, from which the neutron structure function F_2n is usually extracted. The IMC data determine the resulting proton d/u quark distribution ratio, extrapolated to x=1, to be 0.23 +- 0.09 with a 90% confidence level. This is well below the SU(6) symmetry limit of 1/2 and significantly above the scalar diquark dominance limit of 0.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2011)·30 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.