Compton-like dark photon production in electron-nucleus collisions

The Compton-like production of massive dark photons is investigated in ultrarelativistic electron-ion collisions considering the kinetic mixing between the dark photon and the Standard Model photon. The quasi-real photons in the heavy ion are described by the EPA approximation and the model is employed to calculate the integrated cross section and event rates as a function of the dark photon mass, mγ′, and mixing parameter, ε. Predictions are shown for electron-ion colliders (EICs) in the mass range 100 ≤ mγ′ ≤ 500 MeV. Numerical results are provided within the kinematic coverage of the planned machines Electron-ion collider in China (EicC), A Polarized Electron-Ion Collider at Jefferson Lab (JLEIC), Electron Ion Collider/USA (EIC), Large Hadron Electron Collider (LHeC) and Future Circular Collider (FCC-eA). It complements existing search strategies for dark photons in the considered mass interval.

Optical Transitions and Excited State Absorption Cross Sections of SrLaGaO4 Doped with Ho3+ Ions

The spectroscopic properties of SrLaGaO4 (SLO) crystal doped with Ho3+ ions were studied in this work. Absorption, emission spectra and decay dynamics of excited states have been measured and discussed using the Judd–Ofelt model. Photoluminescence emissions were attributed to transitions from the excited 3D3, 5S2, 5F5, 5I6 and 5I7 multiplet manifolds. The experimental lifetimes for five excited states have been compared to the theoretical values, calculated using Judd–Ofelt theory, allowing for the determination of the multiphonon relaxation rates (WnR) of the respective states. The experimental data were approximately on a line expressed by WnR = W0 exp(−αΔE) with W0 = 0.5 × 107 s−1 and α = 2.6 × 10−3 cm. To discuss the excited state absorption (ESA) pathways, that originated from several excited levels, we used the Judd–Ofelt formalism allowing determination of the integrated cross section for ESA transitions.

Integrated cross-section interface engineering and surface encapsulating strategy: a high-response, waterproof, and low-cost paper-based bending strain sensor

In recent years, the paper-based bending strain (PBS) sensor for bending deformation and angle detections has attracted much attention in flexible electronics. However, the PBS sensor based on the surface...

Installation of NEOPTOLEMOS, the new sum spectrometer for cross section measurements of capture reactions at the ΤANDEM Accelerator Laboratory of NCSR “Demokritos”

Cross-section measurements of capture reactions are of key importance in understanding the contribution of the uncertainties of nuclear properties, such as the nucleon-nucleus potential and the nuclear level densities, entering in astrophysics abundance calculations. During the recent years, the Nuclear Astrophysics group of NCSR “Demokritos” has been conducting angle-integrated cross-section measurements using a large-volume NaI(Tl) detector installed at the Dynamitron Tandem Laboratory of the University of Bochum in Germany. Thanks to LIBRA funds a brand new cylindrically shaped NaI(Tl) detector, coined NEOPTOLEMOS, was acquired that is axially segmented in two, covering a solid angle of almost 4π for γ rays emitted at its center.

Test of Time-Reversal Symmetry in the Proton-Deuteron Scattering

The integrated cross section [Formula: see text] for a special type of double polarized proton-deuteron scattering constitutes a null test for time-invariance violating but P-parity conserving effects. Using Glauber theory for the [Formula: see text] elastic scattering and different types of phenomenological T-odd P-even NN-interactions we show that the contribution of the lowest mass meson exchange, i.e. the [Formula: see text]-meson, to the null-test signal [Formula: see text] vanishes. Variation of the cross section [Formula: see text] due to strong hadronic and Coulomb interaction is studied and its energy dependence is calculated in the GeV region.

EXPERIMENTAL TESTS ON THE LIFETIME ASYMMETRY

The experimental test problem of the left–right polarization-dependent lifetime asymmetry is discussed. It shows that the existing experiments cannot demonstrate the lifetime asymmetry to be right or wrong after analyzing the measurements on the neutron, the muon and the tau lifetime, as well as the g-2 experiment. However, it is pointed out emphatically that the SLD and the E158 experiments, the measurements of the left–right integrated cross section asymmetry in Z boson production by e+e- collisions and by electron–electron Møller scattering, can indirectly demonstrate the lifetime asymmetry. In order to directly demonstrate the lifetime asymmetry, we propose some possible experiments on the decays of polarized muons. The precise measurement of the lifetime asymmetry could have important significance for building a muon collider, also in cosmology and astrophysics. It would provide a sensitive test of the standard model in particle physics and allow for exploration of the possible V+A interactions.