Research Article
The Neutron Lifetime Puzzle and a Tube Test for
Velocity-dependent and Geometry-dependent Contributions
Alexandar Balevsky*
,
Krasimira Ivanova
Issue:
Volume 15, Issue 3, June 2026
Pages:
71-76
Received:
9 April 2026
Accepted:
21 April 2026
Published:
29 April 2026
DOI:
10.11648/j.ajmp.20261503.11
Downloads:
Views:
Abstract: This article presents a conservative phenomenological framework for discussing the free-neutron lifetime discrepancy in terms of possible geometry-dependent transport and storage contributions superposed on a common intrinsic time scale. The purpose is not to replace the standard weak-decay description, but to formulate an experimentally testable discriminator capable of separating predominantly velocity-dependent from configuration-dependent effects in the extraction of the neutron lifetime. As a starting point, a compact intrinsic-scale layer is used to introduce a working reference value τ₀ ≈ 877.77s. On top of this baseline, two effective correction channels are added. The first is a weak transport or alignment term for a straight tube geometry, suppressed in first approximation approximately as 1/v2. The second is a configuration-mixing term associated with storage or bottle setups, isotropization, and wall-induced scrambling. This leads to a direct and testable expectation: in one and the same straight decay-tube geometry, measurements across a broad speed interval should show either near constancy or only a weak residual speed dependence, whereas larger deviations would point more naturally to storage-specific mixing effects. The formulation is intentionally moderate. It is not presented as derived from QED, nor as a replacement for the standard theory of beta decay. Instead, it is proposed as an effective test framework written in notation-compatible form with respect to the standard operator language and directed toward a concrete straight-tube experiment.
Abstract: This article presents a conservative phenomenological framework for discussing the free-neutron lifetime discrepancy in terms of possible geometry-dependent transport and storage contributions superposed on a common intrinsic time scale. The purpose is not to replace the standard weak-decay description, but to formulate an experimentally testable d...
Show More
Research Article
Numerical Simulation of Time Domain Thermoacoustic Wave Equation Using the FDTD Method with Comparison to the k-Space Pseudospectral Approach
Ujjal Mandal*
Issue:
Volume 15, Issue 3, June 2026
Pages:
77-85
Received:
26 March 2026
Accepted:
8 April 2026
Published:
7 May 2026
DOI:
10.11648/j.ajmp.20261503.12
Downloads:
Views:
Abstract: This study presents a comprehensive numerical investigation of thermoacoustics (TA) wave propagation in the time domain using the Finite Difference Time Domain (FDTD) method, with a comparative analysis against the k-space pseudospectral approach. The TA wave equation is modeled under the assumptions of homogeneous, lossless, and isotropic medium, incorporating a physically realistic source term. A Gaussian initial pressure distribution is employed as the primary excitation, and the resulting acoustic signals are recorded using point and multi-sensor configurations. The study systematically the influence of spatial grid resolution and the Courant-Friedrichs-Lewy (CFL) number on numerical stability and accuracy. It is observed that maintaining a constant CFL number ensures consistent wave propagation behavior across different grid resolutions, whereas variations in CFL lead to significant discrepancies in amplitude and phase of the propagated signals. In addition to Gausian sources, various realistic source geometries, including circular disk, Chebyshev polynomial-based, and asymmetric (rock-like) distributions, are investigated to analyze their impact on wavefield characteristics. The numerical results demonstrate strong agreement between the FDTD and k-space method in both time and frequency domains under stable conditions. However, deviations are observed at higher frequencies due to numerical dispersion effects, particularly in the FDTD scheme. Furthermore, it is shown that sharp discontinuities in binary image based sources introduce non-physical high-frequency components, resulting in spurious oscillations. This study highlights the importance of numerical parameter selection, particularly the CFL condition, and provides a detailed comparision of two widely used computational methods for TA wave simulation. The findings offer valuable insights into the role of source geometry and numerical schemes in accurately modeling acoustic wave propagation.
Abstract: This study presents a comprehensive numerical investigation of thermoacoustics (TA) wave propagation in the time domain using the Finite Difference Time Domain (FDTD) method, with a comparative analysis against the k-space pseudospectral approach. The TA wave equation is modeled under the assumptions of homogeneous, lossless, and isotropic medium, ...
Show More
