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Abstract Lifetimes of excited states in$$^{162}$$ $_{}^{162}$ Dy were measured using the (n,n’$$\gamma $$ $\gamma$ ) reaction with the Doppler-Shift Attenuation Method (DSAM) at the University of Kentucky’s Accelerator Laboratory. A total of eighteen level lifetimes were obtained, including eleven negative-parity states, seven of which are new. These measurements significantly expand the experimental database of transition probabilities for negative-parity bands in the well-deformed rare earth region of nuclei. The extracted B(E1) and B(E2) values reveal enhanced interband E1 ($$10^{-3}$$ ${10}^{-3}$ or$$10^{-4}$$ ${10}^{-4}$ ) W.u. and E2 strengths (several W.u.) between negative- and positive parity bands, particularly for the KEquation missing<#comment/>bands decaying to the the K$$^{\pi }=2^+_{\gamma }$$ $_{}^{\pi }=2_{\gamma }^{+}$ band, consistent with signatures of octupole-quadrupole coupling. In contrast, the K$$^{\pi }=0^-_1$$ $_{}^{\pi }=0_1^{-}$ and K$$^{\pi }=1^-_3$$ $_{}^{\pi }=1_3^{-}$ bands, which exhibit strong E1 transitions to the ground state band, are indicative of octupole-vibrational excitations built on the deformed ground state. Comparison of transition rates with Alaga rules supports this interpretation and distinguishes collective excitations from likely quasi-particle states. These new results establish$$^{162}$$ $_{}^{162}$ Dy as the most extensively characterized rare-earth nucleus for negative parity lifetimes and provide critical experimental benchmarks for theoretical models. 

Abstract The low-lying structure of the well-deformed nucleus$$^{158}$$ $_{}^{158}$ Gd has been revisited to elucidate the nature of the low-lying states in$$^{158}$$ $_{}^{158}$ Gd. Earlier (p, t) studies identified numerous 0$$^+$$ $_{}^{+}$ states below 4.3 MeV, prompting questions about whether these states correspond to collective vibrations or shape coexistence. New and previously reported ($$n,n^\prime \gamma $$ $n,n^{\prime }\gamma$ ) measurements are combined, including$$\gamma $$ $\gamma$ -$$\gamma $$ $\gamma$ coincidences, excitation functions, and angular distributions, to extract lifetimes and transition probabilities for 44 excited states up to 2.7 MeV, including 32 previously unmeasured levels. Our results confirm or revise$$\gamma $$ $\gamma$ -ray placements and provide detailed transition strengths, revealing both weakly collective and strongly enhanced B(E2) and B(E1) transition probabilities. In particular, a tentative 0$$^+$$ $_{}^{+}$ state at 2437.8 keV exhibits a strong interband B(E2) transition, which may be a candidate for a possible two-phonon ($$\beta \beta $$ $\beta \beta$ ) excitation. Systematic comparisons with neighboring Gd isotopes, Hartree–Fock–Bogoliubov, and interacting-boson model predictions suggest that the first excited 0$$^+$$ $_{}^{+}$ state in$$^{158}$$ $_{}^{158}$ Gd is predicted to be a$$\beta $$ $\beta$ -vibration, although it is weakly collective. We also present results for lifetimes and transition probabilities for a number of negative parity states, including$$\hbox {K}^{\pi }=0^-,1^-,2^-$$ ${\text{K}}^{\pi }=0^{-},1^{-},2^{-}$ sequences, perhaps providing insight into octupole collectivity and the interplay between quadrupole and octupole vibrations in deformed nuclei. The systematic presence of low-lying negative-parity bands and their interband transition strengths suggest that$$^{158}$$ $_{}^{158}$ Gd’s potential energy surface may support both quadrupole and octupole vibrational modes, in agreement with microscopic calculations [1–3]. 

Abstract Neutron-induced reactions play an important role in fundamental nuclear physics, nuclear astrophysics, and applications. In the case of reactions on rare isotopes, there are limited options for direct experimental measurements. The Neutron Target Demonstrator project at Los Alamos National Laboratory seeks to test the feasibility of moderating spallation neutrons within a 1 m$$^3$$ $_{}^3$ graphite cube to create a standing neutron target for neutron-induced reaction measurements in inverse kinematics. This paper presents the results of experimental neutron flux distribution tests using neutron sources (ranging from 1 keV to 50 MeV) created by accelerators at the University of Notre Dame and Texas A&M University. Measurements were made with both the full graphite cube as well as a ”half cube” setup in which half of the graphite cube was removed. The measured distributions agree with simulated distributions in the case of the full cube moderator, although there remain discrepancies in certain cases for the half cube moderator. The results shown here will provide useful information for an upcoming experimental campaign to test the neutron target proof-of-principle. 

Abstract A new type of radio frequency (RF) timing technique is presented. It is based on a helical deflector, which performs circular or elliptical sweeps of photo- or secondary electrons, accelerated to keV energies, by means of RF fields in the 500–1000 MHz range. By converting a time distribution of the electrons to a hit position distribution on a circle or ellipse, this device achieves extremely precise timing, similar to streak cameras. Detection of the scanned electrons, using a position sensitive detector based on microchannel plates and a delay line anode, resulted in a timing resolution of 10 ps, which can be potentially improved to 1 ps. RF-Timer-based single photon and heavy ion detectors have potential applications in different fields of science and industry, which include high energy nuclear physics and imaging technologies. This technique could play a crucial role in developing of sub 10 ps Time-of-Flight Positron Emission Tomography.