Mon·Mar 18, 2019Monday·March 18, 2019

1. 01*

   Search for dark photon, axion-like particles, dark scalar, or light dark matter in Compton-like processes

   Sankha S. Chakrabarty🇺🇸 · Igal Jaeglé🇺🇸

   We propose a novel way to search for the dark photon ($A^{\prime }$), the axion-like pseudo-scalar ($a$), the dark scalar ($\varphi$), and the light dark matter ($\chi$) in the Compton-like processes, $\gamma +e^{-}\to A^{\prime }/a/\varphi +e^{-}$ with $A^{\prime }/a/\varphi$ decaying into leptons, photons, or $\chi$'s (when permitted) for the mass ranges of $m_{A^{\prime }/a/\varphi }\le$ 100 MeV/$c^2$ and $m_{\chi }\le$ 50 MeV/$c^2$. We examine how the past, current, and future fixed target experiments can use this under-explored production mechanism of dark particles. We show that the existing and planned tagged photon beam fixed-target experiments (GlueX, LEPS2, LEPS, and FOREST) are competitive with the electron beam fixed target experiments, particularly for searching an invisible particle. We also show that the photon flux produced in the beam dump experiments increases the dark particle flux significantly and therefore the sensitivities of these experiments. By only considering the Compton-like processes, we determine the new limits and expected sensitivities for several beam dump and active beam dump experiments (E774, E141, KEK, Orsay, E137, NA64, BDX and LDMX) on the kinetic mixing parameter ($ϵ$) between the dark photon and the Standard Model photon, the axion-like pseudo-scalar coupling to electrons ($g_{ae}$), the dark scalar coupling to electrons ($y_e$) and the dimensionless interaction strength ($y$) to light dark matter.

   ↳ hep-phhep-exnucl-ex14 citations
2. 02*

   Relating eccentricity fluctuations to density fluctuations in heavy-ion collisions

   Rajeev S. Bhalerao🇮🇳 · Giuliano Giacalone🇫🇷 · Pablo Guerrero-Rodríguez🇪🇸 · Matthew Luzum🇧🇷 · Cyrille Marquet🇫🇷 · Jean-Yves Ollitrault🇫🇷

   The magnitude of anisotropic flow in a nucleus-nucleus collision is determined by the energy density field, $\rho (x,y,z)$, created right after the collision occurs. Specifically, elliptic flow, $v_2$, and triangular flow, $v_3$, are proportional to the anisotropy coefficients ${\epsilon }_2$ and ${\epsilon }_3$, which are functionals of $\rho$. We express the mean and the variance of ${\epsilon }_2$ and ${\epsilon }_3$ as a function of the 1- and 2-point functions of $\rho$. These results generalize results obtained previously, that were valid only for central collisions, or only for identical point-like sources. We apply them to the color glass condensate effective theory, using the recently derived expression of the 2-point function.

   ↳ nucl-thhep-phnucl-exActa Phys.Polon.B(2019)·12 citations
3. 03*

   Time-dependent Hartree-Fock plus Langevin approach for hot fusion reactions to synthesize the $Z=120$ superheavy element

   K. Sekizawa🇯🇵 · K. Hagino

   We develop a novel approach to fusion reactions for syntheses of superheavy elements, which combines the time-dependent Hartree-Fock (TDHF) method with a dynamical diffusion model based on the Langevin equation. In this approach, the distance of the closest approach for the capture process is estimated within the TDHF approach, which is then plugged into the dynamical diffusion model as an initial condition. We apply this approach to hot fusion reactions leading to formation of the element $Z=120$, that is, the ${}^{48}$Ca+${}^{254,257}$Fm, ${}^{51}$V+${}^{249}$Bk, and ${}^{54}$Cr+${}^{248}$Cm reactions. Our calculations indicate that the distances of the closest approach for these systems are similar to each other and thus the difference in the probabilities of evaporation residue formation among those reaction systems originates mainly from the evaporation process, which is sensitive to the fission barrier height and the excitation energy of a compound nucleus.

   ↳ nucl-thnucl-exPRC(2019)·51 citations
4. 04*

   High-resolution spectroscopy of gaseous ${}^{83m}$Kr conversion electrons with the KATRIN experiment

   K. Altenmüller🇩🇪 · M. Arenz🇩🇪 · W.-J. Baek🇩🇪 · M. Beck🇩🇪 · A. Beglarian🇩🇪 · J. Behrens🇩🇪 · T. Bergmann🇩🇪 · A. Berlev🇷🇺 · U. Besserer🇩🇪 · K. Blaum🇩🇪 · F. Block🇩🇪 · S. Bobien🇩🇪 and 115 other authors

   In this work, we present the first spectroscopic measurements of conversion electrons originating from the decay of metastable gaseous ${}^{83m}$Kr with the Karlsruhe Tritium Neutrino (KATRIN) experiment. The results obtained in this calibration measurement represent a major commissioning milestone for the upcoming direct neutrino mass measurement with KATRIN. The successful campaign demonstrates the functionalities of the full KATRIN beamline. The KATRIN main spectrometer's excellent energy resolution of ~ 1 eV made it possible to determine the narrow K-32 and L${}_3$-32 conversion electron line widths with an unprecedented precision of ~ 1 %.

   ↳ physics.ins-detnucl-exJ.Phys.G(2020)·27 citations
5. 05*

   GADGET: A Gas Amplifier Detector with Germanium Tagging

   Moshe Friedman🇺🇸 · David Pérez-Loureiro🇺🇸 · Tamas Budner🇺🇸 · Emanuel Pollacco🇫🇷 · Chris Wrede🇺🇸 · Marco Cortesi🇺🇸 · Cathleen Fry🇺🇸 · Brent Glassman🇺🇸 · Madison Harris🇺🇸 · Joe Heideman🇺🇸 · Molly Janasik🇺🇸 · Brian T Roeder🇺🇸 and 6 other authors

   The Gas Amplifier Detector with Germanium Tagging (GADGET) is a new detection system devoted to the measurement of weak, low-energy $\beta$-delayed proton decays relevant for nuclear astrophysics studies. It is comprised of a new gaseous Proton Detector equipped with a Micromegas readout for charged particle detection, surrounded by the existing Segmented Germanium Array (SeGA) for the high-resolution detection of the prompt $\gamma$-rays. In this work we describe in detail for the first time the design, construction, and operation of the GADGET system, including performance of the Proton Detector. We present the results of a recent commissioning experiment performed with \textsuperscript{25}Si beam at the National Superconducting Cyclotron Laboratory (NSCL). GADGET provided low-background, low-energy $\beta$-delayed proton detection with efficiency above 95\%, and relatively good efficiency for proton-gamma coincidences (2.7\% at 1.37 MeV).

   ↳ physics.ins-detnucl-exNucl.Instrum.Meth.A(2019)·17 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.