Fri·Mar 24, 2017Friday·March 24, 2017

1. 01*

   Experimentally Study the Deep Dirac Levels with High-Intensity Lasers

   Xiaopeng Zhang · Changbo Fu🇨🇳 · Dechang Dai

   Various theories have predicted the deep Dirac levels (DDLs) in atoms for many years. However, the existence of the DDL is still under debating, and need to be confirmed experimentally. With the development of high intensive lasers, nowadays, electrons can been accelerated to relativistic energy by high intensive lasers, electron-positron pairs can be created, and nuclear reactions can been ignited, which provide a new tool to explore the DDL related fields. In this paper, we propose a new experimental method to study the DDL levels by monitoring nuclei's orbital electron capture life time in plasma induced by high intensive lasers. If a DDL exists, a nuclear electron capture rate could be enhanced by factor of over $10^7$, which makes it practically detectable in nowadays high intensive laser environments.

   nucl-exnucl-th0 citations
2. 02*

   $\Delta$(1232) Dalitz decay in proton-proton collisions at T=1.25 GeV measured with HADES

   J. Adamczewski-Musch (4) · O. Arnold (9 and 10) · E. T. Atomssa (15) · C. Behnke (8) · A. Belounnas (15) · A. Belyaev (7) · J. C. Berger-Chen (9 and 10) · J. Biernat (3) · A. Blanco (2) · C. Blume (8) · M. Böhmer (10) · P. Bordalo (2) and 105 other authors

   We report on the investigation of $\Delta$(1232) production and decay in proton-proton collisions at a kinetic energy of 1.25 GeV measured with HADES. Exclusive dilepton decay channels $pp{e}^{+}{e}^{-}$ and $pp{e}^{+}{e}^{-}\gamma$ have been studied and compared with the partial wave analysis of the hadronic $pp{\pi }^0$ channel. They allow to access both ${\Delta }^{+}\to p{\pi }^0(e^{+}{e}^{-}\gamma )$ and ${\Delta }^{+}\to p{e}^{+}{e}^{-}$ Dalitz decay channels. The perfect reconstruction of the well known ${\pi }^0$ Dalitz decay serves as a proof of the consistency of the analysis. The $\Delta$ Dalitz decay is identified for the first time and the sensitivity to N-$\Delta$ transition form factors is tested. The $\Delta$(1232) Dalitz decay branching ratio is also determined for the first time; our result is (4.19 $\pm$ 0.62 syst. $\pm$ 0.34 stat.) $\times$ 10${}^{-5}$, albeit with some model dependence.

   nucl-exPRC(2017)·56 citations
3. 03*

   Design and construction of a high-energy photon polarimeter

   M. Dugger🇺🇸 · B. G. Ritchie🇺🇸 · N. Sparks🇺🇸 · K. Moriya🇺🇸 · R. J. Tucker · R. J. Lee · B. N. Thorpe · T. Hodges · F. J. Barbosa · N. Sandoval🇺🇸 · R. T. Jones🇺🇸

   We report on the design and construction of a high-energy photon polarimeter for measuring the degree of polarization of a linearly-polarized photon beam. The photon polarimeter uses the process of pair production on an atomic electron (triplet production). The azimuthal distribution of scattered atomic electrons following triplet production yields information regarding the degree of linear polarization of the incident photon beam. The polarimeter, operated in conjunction with a pair spectrometer, uses a silicon strip detector to measure the recoil electron distribution resulting from triplet photoproduction in a beryllium target foil. The analyzing power ${\Sigma }_A$ for the device using a 75 $\mu \mathrm{m}$ beryllium converter foil is about 0.2, with a relative systematic uncertainty in ${\Sigma }_A$ of 1.5%.

   ↳ physics.ins-detnucl-exNucl.Instrum.Meth.A(2017)·37 citations
4. 04*

   Dynamical evolution of critical fluctuations and its observation in heavy ion collisions

   Miki Sakaida🇯🇵 · Masayuki Asakawa🇯🇵 · Hirotsugu Fujii🇯🇵 · Masakiyo Kitazawa🇯🇵

   We study time evolution of critical fluctuations of conserved charges near the QCD critical point in the context of relativistic heavy ion collisions. A stochastic diffusion equation is employed in order to describe the diffusion property of the critical fluctuation arising from the coupling of the order parameter field to conserved charges. We show that the diffusion property gives rise to a possibility of probing the early time fluctuations through the rapidity window dependence of the second-order cumulant and correlation function of conserved charges. It is pointed out that their non-monotonic behaviors as functions of the rapidity interval are robust experimental signals for the existence of the critical enhancement around the QCD critical point.

   ↳ nucl-thhep-phnucl-exPRC(2017)·44 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.