Tue·Dec 17, 2019Tuesday·December 17, 2019

1. 01*

   Compton scattering from ${}^4$He at the TUNL HI$\gamma$S facility

   X. Li🇺🇸 · M.W. Ahmed🇺🇸 · A. Banu🇺🇸 · C. Bartram🇺🇸 · B. Crowe🇺🇸 · E.J. Downie🇺🇸 · M. Emamian🇺🇸 · G. Feldman🇺🇸 · H. Gao🇺🇸 · D. Godagama🇺🇸 · H.W. Grießhammer🇺🇸 · C.R. Howell🇺🇸 and 17 other authors

   Differential cross sections for elastic Compton scattering from ${}^4$He have been measured with high statistical precision at the High Intensity $\gamma$-ray Source at laboratory scattering angles of $55^{\circ }$, $90^{\circ }$, and $125^{\circ }$ using a quasi-monoenergetic photon beam with a weighted mean energy value of $81.3$ MeV. The results are compared to previous measurements and similar fore-aft asymmetry in the angular distribution of the differential cross sections is observed. This experimental work is expected to strongly motivate the development of effective-field-theory calculations of Compton scattering from ${}^4$He to fully interpret the data.

   nucl-exhep-exhep-phnucl-thPRC(2020)·9 citations
2. 02*

   Precise measurement of $2\nu \beta \beta$ decay of ${}^{100}$Mo with the CUPID-Mo detection technology

   E. Armengaud🇫🇷 · C. Augier🇫🇷 · A. S. Barabash🇷🇺 · F. Bellini🇮🇹 · G. Benato🇺🇸 · A. Benoît🇫🇷 · M. Beretta🇮🇹 · L. Bergé🇫🇷 · J. Billard🇫🇷 · Yu. A. Borovlev🇷🇺 · Ch. Bourgeois🇫🇷 · M. Briere🇫🇷 and 78 other authors

   We report the measurement of the two-neutrino double-beta ($2\nu \beta \beta$) decay of ${}^{100}$Mo to the ground state of ${}^{100}$Ru using lithium molybdate (\crystal) scintillating bolometers. The detectors were developed for the CUPID-Mo program and operated at the EDELWEISS-III low background facility in the Modane underground laboratory. From a total exposure of $42.235$ kg$\times$d, the half-life of ${}^{100}$Mo is determined to be $T_{1/2}^{2\nu }=[7.12_{-0.14}^{+0.18}(stat.)\pm 0.10(syst.)]\times 10^{18}$ years. This is the most accurate determination of the $2\nu \beta \beta$ half-life of ${}^{100}$Mo to date. We also confirm, with the statistical significance of $>3\sigma$, that the single-state dominance model of the $2\nu \beta \beta$ decay of ${}^{100}$Mo is favored over the high-state dominance model.

   nucl-exphysics.ins-detEPJC(2020)·63 citations
3. 03*

   Generalized Lomb-Scargle analysis of ${}^{36}\mathrm{Cl}$ decay rate measurements at PTB and BNL

   Akanksha Dhaygude · Shantanu Desai🇮🇳

   Recently, Pomme et al did an analysis of ${}^{36}\mathrm{Cl}$ radioactive decay data from measurements at the Physikalisch-Technische Bundesanstalt (PTB), in order to verify the claims by Sturrock and collaborators of an influence on beta-decay rates measured at Brookehaven National Lab (BNL) due to the rotation-induced modulation of the solar neutrino flux. Their analysis excluded any sinusoidal modulations in the frequency range from 0.2-20/year. We carry out an independent analysis of the same PTB and BNL data using the generalized Lomb-Scargle periodogram, to look for any statistically significant peaks in the range from 0 to 14 per year, and by evaluating the significance of every peak using multiple methods. Our results for the PTB data are in agreement with those by Pomme et al. For BNL data, we do find peaks at some of the same frequencies as Sturrock et al, but the significance is much lower. All our analysis codes and datasets have been made publicly available.

   ↳ astro-ph.HEastro-ph.IMnucl-exEPJC(2020)·4 citations
4. 04*

   Systematic study on production of hidden-bottom pentaquark via $\gamma p$ and ${\pi }^{-}p$ scatterings

   Xiao-Yun Wang🇨🇳 · Jun He🇨🇳 · Xurong Chen🇨🇳

   The production of hidden-bottom pentaquark $P_b$ states via $\gamma p$ and ${\pi }^{-}p$ scatterings is studied within an effective Lagrangian approach and the vector-meson-dominance mechnism. For the $P_b$ production in the process $\gamma p\to {\rm Y}p$, the dipole Pomeron model is employed to calculate the background contribution, and the experimental data can be well described. For the process ${\pi }^{-}p\to {\rm Y}n$, the Reggeized $t$-channel with $\pi$ exchange is considered as the main background for the $P_b$ production. Near the threshold, two-peak structure from the states P_{b (11080) and $P_b(11125)$ can be observed if energy bin width is chosen as 0.01 GeV, and the same result is obtained in the ${\pi }^{-}p$ scattering. Moreover, by taking the branching ratio of Br$[P_b\to \pi N]\simeq 0.05\%$, the numerical result shows that the average value of cross section from the $P_b(11080)$ state produced in the $\gamma p$ or ${\pi }^{-}p$ scattering reaches at least 0.1 nb with a bin of 0.1 GeV. Even if we reduce the branching ratio of the $P_b$ state into $\pi N$ channel by one order, the theoretical average of the cross section from $P_b(11080)$ production in ${\pi }^{-}p$ scattering can reach the order of 0.01 nb with a bin of 0.1 GeV, which means that the signal can still be clearly distinguished from the background. The experimental measurements and studies on the hidden-bottom pentaquark $P_b$ state production in the $\gamma p$ or ${\pi }^{-}p$ scattering near-threshold energy region around $W\simeq 11$ GeV are strongly suggested, which are accessible at COMPASS and JPARC. Particularly, the result of the photoproduction suggests that it is very promising to observe the hidden-bottom pentaquark at proposed EicC facility in China.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2020)·21 citations
5. 05*

   Two-particle azimuthal correlations as a probe of collective behaviour in deep inelastic $\text{ep}$ scattering at HERA

   ZEUS Collaboration

   Two-particle azimuthal correlations have been measured in neutral current deep $\text{mbox}inelastic$ $\text{ep}$ scattering with virtuality $Q^2>5$ GeV${}^2$ at a centre-of-mass energy $\sqrt{s}=318$ GeV recorded with the ZEUS detector at HERA. The correlations of charged particles have been measured in the range of laboratory pseudorapidity $-1.5<\eta <2.0$ and transverse momentum $0.1<p_{\text{T}}<5.0$ GeV and event multiplicities $N_{\text{ch}}$ up to six times larger than the average $⟨N_{\text{ch}}⟩\approx 5$. The two-particle correlations have been measured in terms of the angular observables $c_n\{2\}=⟨⟨\cos n\Delta \phi ⟩⟩$, where $n$ is between 1 and 4 and $\Delta \phi$ is the relative azimuthal angle between the two particles. Comparisons with available models of deep inelastic scattering, which are tuned to reproduce inclusive particle production, suggest that the measured two-particle correlations are dominated by contributions from multijet production. The correlations observed here do not indicate the kind of collective behaviour recently observed at the highest RHIC and LHC energies in high-multiplicity hadronic collisions.

   ↳ hep-exhep-phnucl-exnucl-thJHEP(2020)·55 citations
6. 06*

   Scintillation balloon for liquid scintillator base Neutrinoless double beta decay search experiments

   S.Obara · Y.Gando · K.Ishidoshiro

   A liquid scintillator base experiment KamLAND-Zen has set a lower limit on neutrinoless double beta decay half-life, and upgrade project KamLAND-Zen 800 has started in 2019. Unfortunately, this project expects some backgrounds, and one of the main backgrounds is beta/gamma-ray from 214Bi in container of xenon loaded liquid scintillator (mini-balloon). In order to reject the background, we suggest using scintillation film for the future mini-balloon. If we can tag alpha-ray from 214Po by scintillation detection, we can eliminate 214Bi events by delayed coincidence analysis. Recently, it was reported that polyethylene naphthalate (PEN) can be used as a scintillator with blue photon emission. PEN has chemical compatibility for strong solvent, thus it has a possibility to use in liquid scintillator. In this presentation, we will mention the results for feasibility studies about transparency and emission spectra, light yield, radioactivity, strength of film etc.. We also show the test-sized scintillation balloon with an 800-mm diameter and discussions about how to use the scintillation balloon in KamLAND.

   ↳ physics.ins-detastro-ph.COnucl-exJ.Phys.Conf.Ser.(2020)·1 citation
7. 07*

   Optimizing neutron moderators for a spallation-driven ultracold-neutron source at TRIUMF

   W. Schreyer🇨🇦 · C. A. Davis🇬🇧 · S. Kawasaki🇯🇵 · T. Kikawa🇯🇵 · C. Marshall🇺🇸 · K. Mishima🇯🇵 · T. Okamura · R. Picker🇨🇦

   We report on our efforts to optimize the geometry of neutron moderators and converters for the TRIUMF UltraCold Advanced Neutron (TUCAN) source using MCNP simulations. It will use an existing spallation neutron source driven by a 19.3 kW proton beam delivered by TRIUMF's 520 MeV cyclotron. Spallation neutrons will be moderated in heavy water at room temperature and in liquid deuterium at 20 K, and then superthermally converted to ultracold neutrons in superfluid, isotopically purified ${}^4$He. The helium will be cooled by a ${}^3$He fridge through a ${}^3$He-${}^4$He heat exchanger. The optimization took into account a range of engineering and safety requirements and guided the detailed design of the source. The predicted ultracold-neutron density delivered to a typical experiment is maximized for a production volume of 27 L, achieving a production rate of $1.4\cdot 10^7$ s${}^{-1}$ to $1.6\cdot 10^7$ s${}^{-1}$ with a heat load of 8.1 W. At that heat load, the fridge can cool the superfluid helium to 1.1 K, resulting in a storage lifetime for ultracold neutrons in the source of about 30 s. The most critical performance parameters are the choice of cold moderator and the volume, thickness, and material of the vessel containing the superfluid helium. The source is scheduled to be installed in 2021 and will enable the TUCAN collaboration to measure the electric dipole moment of the neutron with a sensitivity of $10^{-27}$ e cm.

   ↳ physics.ins-detnucl-exphysics.acc-phNucl.Instrum.Meth.A(2020)·23 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.