Fri·Feb 21, 2025Friday·February 21, 2025

1. 01*

   Independent check of sporadic beta decay anomalies reported earlier by Parkhomov

   Andrei E. Egorov🇷🇺 · Aleksey A. Alekseev🇵🇱

   A. Parkhomov reported in the past the detection of strong, short, sporadic, nearly everyday decay rate increases in $\beta$-isotopes placed at the focus of a concave mirror directed at a clear sky. He interpreted this effect as neutrino-induced decay. These neutrinos were assumed to be slow and arrive from space in the form of gravitationally collimated beams. We precisely replicated this experiment for the purpose of independent verification. We recorded about 50 days of data employing Geiger-counter-based signal and control detectors, ${}^{40}$K and ${}^{90}$Sr/${}^{90}$Y isotopes as $\beta$-sources. We did not detect any significant difference between the data from signal and control detectors, both datasets obeyed the standard Poissonian process. Thus, we robustly excluded the hypothesized new effect. We suspect that A. Parkhomov was just misled by a trivial electromagnetic instability of his setup.

   nucl-exhep-phNPB(2025)·0 citations
2. 02*

   MoNA -- The first 25 years

   A. Banu🇺🇸 · T. Baumann · J. Brown · P. A. DeYoung · J. Finck · N. Frank · P. Gueye🇺🇸 · J. Hinnefeld · C. Hoffman · A. N. Kuchera🇺🇸 · B. A. Luther · B. Monteagudo-Gudoy and 4 other authors

   The Modular Neutron Array (MoNA) collaboration was initiated in 2000 at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University (MSU). Since then, the collaboration studied properties of nuclides at and beyond the neutron dripline discovering seven new isotopes between lithium to fluorine. The collaboration included liberal arts colleges, regional comprehensive universities, and major research universities with the focus of giving undergraduate students meaningful research experiences. Over the last 25 years, the combined efforts of hundreds of undergraduates, dozens of graduate students and research associates, and faculty from more than a dozen colleges and universities produced over fifty publications, won awards for research, and combined research and teaching in new and interesting ways.

   nucl-exphysics.ed-phphysics.hist-ph0 citations
3. 03*

   Temperature Dependence of Beam on Plasma Stopping Power in the Resonance Regions of Fusion Reactions

   Keh-Fei Liu🇺🇸

   A recent proposal of accelerator based fusion reactor considers a scheme where an ion beam from the accelerator hits the target plasma on the resonance of the fusion reaction so that the reactivity ($\sigma v$) can be an order of magnitude larger than that of a thermonuclear reactor. One of the important inputs is the stopping power which is needed to assess the energy loss of the beam in the plasma. In this work, we shall use the analytic formulation of Brown, Preston and Singleton~\cite{Brown:2005ji} to calculate the temperature dependence of the stopping power due to the target $t,{}^3{H}_e$, and ${}^{11}B$ plasmas in the resonance regions of their respective fusion reactions, i.e., $d+t\to n+\alpha ,d+{}^3{H}_e\to p+\alpha$, and $p+{}^{11}B\to 3\alpha$. It is found that the calculated stopping power, especially when the quantum corrections are included, does not go down with temperature as fast at $T^{-3/2}$. Instead it decreases slower, more like $T^{-x}$ with $x\le 1$ in the range of T from $\sim$ 5 to 50 keV for $d$ on $t$ and ${}^3{H}_e$ plasmas around their resonance energies.

   ↳ physics.plasm-phnucl-exnucl-thphysics.acc-phPlasma Phys.(2024)·0 citations
4. 04*

   Puzzling $B(E2;0^{+}\to 2^{+})$ strength in the proton dripline nucleus ${}^{36}$Ca

   Z. C. Xu🇨🇳 · S. M. Wang🇨🇳 · T. Beck · A. Gade🇺🇸 · W. Nazarewicz🇺🇸

   Recent measurements of the $E2$ transition rate from the ground state to the first 2${}^{+}$ excited state of the proton dripline nucleus ${}^{36}$Ca show an unusual pattern when compared to its isotopic neighbor ${}^{38}$Ca: despite having a higher $E_x(2_1^{+})$ excitation energy, the $B(E2;0_1^{+}\to 2_1^{+})$ rate in ${}^{36}$Ca is larger. The question that naturally arises is to what extent this observation can be attributed to the unbound character of the $2_1^{+}$ state. To understand the influence of the continuum space on the low-energy properties of ${}^{36}$Ca, we carried out Gamow shell model calculations that can account for the continuum coupling effects associated with the occupation of unbound $fp$ shells. We found that in the threshold $2^{+}$ state, ${}^{36}$Ca is spatially diffused, which impacts the observed $B(E2)$ trend.

   ↳ nucl-thnucl-exPRC(2025)·3 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.