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Free neutron decay is the prototype for nuclear beta decay and other semileptonic weak particle decays. It provides important insights into the symmetries of the weak nuclear force. Neutron decay is important for understanding the formation and abundance of light elements in the early universe. The two main experimental approaches for measuring the neutron lifetime, the beam method and the ultracold neutron storage method, have produced results that currently differ by 9.8 ± 2.0 s. While this discrepancy probably has an experimental origin, a more exciting prospect is that it may be explained by new physics, with possible connections to dark matter. The experimental status of the neutron lifetime is briefly reviewed, with an emphasis on its implications for cosmology, astrophysics, and dark matter. [ABSTRACT FROM AUTHOR]

The author shares his experience of working with the Indian theoretical physicist, George Sudarshan. Topics discussed include information on the development of the V-A theory of weak interactions; discussions on the beta decay theory of the American-Italian physicist, Enrico Fermi; and the information on the concepts of the electromagnetism.

Specific environmental applications can benefit from dual tritium and radiocarbon measurements in a single compound. Assuming typical environmental levels, it is often the low tritium activity relative to the higher radiocarbon activity that limits the dual measurement. In this paper, we explore the parameter space for a combined tritium and radiocarbon measurement using a natural methane sample mixed with an argon fill gas in low-background proportional counters of a specific design. We present an optimized methane percentage, detector fill pressure, and analysis energy windows to maximize measurement sensitivity while minimizing count time. The final optimized method uses a 9-atm fill of P35 (35% methane, 65% argon), and a tritium analysis window from 1.5 to 10.3 keV, which stops short of the tritium beta decay endpoint energy of 18.6 keV. This method optimizes tritium-counting efficiency while minimizing radiocarbon beta-decay interference. [ABSTRACT FROM AUTHOR]

In the presence of magnetic helicity, inverse transfer from small to large scales is well known in magnetohydrodynamic (MHD) turbulence and has applications in astrophysics, cosmology, and fusion plasmas. Using high resolution direct numerical simulations of magnetically dominated self-similarly decaying MHD turbulence, we report a similar inverse transfer even in the absence of magnetic helicity. We compute for the first time spectral energy transfer rates to show that this inverse transfer is about half as strong as with helicity, but in both cases the magnetic gain at large scales results from velocity at similar scales interacting with smaller-scale magnetic fields. This suggests that both inverse transfers are a consequence of universal mechanisms for magnetically dominated turbulence. Possible explanations include inverse cascading of the mean squared vector potential associated with local near two dimensionality and the shallower k2 subinertial range spectrum of kinetic energy forcing the magnetic field with a k4 subinertial range to attain larger-scale coherence. The inertial range shows a clear k-2 spectrum and is the first example of fully isotropic magnetically dominated MHD turbulence exhibiting weak turbulence scaling. [ABSTRACT FROM AUTHOR]

We propose the first event-by-event directional antineutrino detector using inverse beta decay (IBD) interactions on hydrogen, with potential applications including monitoring for nuclear nonproliferation, spatially mapping geoneutrinos, characterizing the diffuse supernova neutrino background and searching for new physics in the neutrino sector. The detector consists of adjacent and separated target and capture scintillator planes. IBD events take place in the target layers, which are thin enough to allow the neutrons to escape without scattering elastically. The neutrons are detected in the thicker boron-loaded capture layers. The location of the IBD event and the momentum of the positron are determined by tracking the positron's trajectory through the detector. Our design is a straightforward modification of existing antineutrino detectors; a prototype could be built with existing technology. [ABSTRACT FROM AUTHOR]

The article discusses a research involving the Monte Carlo Hauser-Feshbach simulations applied for selected quantities that characterizes the prompt γ rays produced in neutron-induced and spontaneous fission reactions. Topics discussed include the initial spin distribution in the fission fragments, the influence of the selected model parameters on the prompt neutron and γ ray spectra, and beta decays and the weak decays of the fission fragments.

TRIUMF’s neutral atom trap for β decay (TRINAT) has been used to measure the most accurate β- ν correlation. Plans include improving that measurement, and also carrying out a full program of spin-polarized β decay correlation measurements complementary to the decay of the neutron [ABSTRACT FROM AUTHOR]

The history of weak interactions starting with Fermi's creation of the beta decay theory and culminating in its modern avatar in the form of the electroweak gauge theory is described. Discoveries of parity violation, matter-antimatter asymmetry, W and Z bosons and neutrino mass are highlighted. [ABSTRACT FROM AUTHOR]

An experiment to observe the bound beta-decay (BOB) of the free neutron into a hydrogen atom and an electron anti-neutrino is described. The hyperfine spin state population of the monoenergetic hydrogen atom yields the neutrino left-handedness or possible right-handed admixture as well as possible small scalar and tensor contributions to the weak force. The BOB H(2s) hyperfine states can be separated with a Lamb-Shift Spin Filter. These monoenergetic H(2s) atoms are ionised into H by charge exchanging within an argon cell. These ions are then separated using an adaptation of a MAC-E Filter. A first experiment is proposed at the FRMII high thermal-neutron flux beam reactor SR6 through-going beam tube, where we will seek to observe this rare neutron decay-mode for the first time and determine the branching ratio. After successful completion, the hyperfine spin state population will be determined, possibly at the ILL high-flux beam reactor through-going beam tube H6-H7, where the thermal neutron flux is a factor of four larger. [ABSTRACT FROM AUTHOR]

Abstract: During the last several years the WITCH (Weak Interaction Trap for CHarged particles) experimental setup at ISOLDE has undergone various upgrades aiming at improvement of general performance. An essential innovation, a compact Radio Frequency Quadrupole (RFQ) ion cooler and buncher device, was designed and successfully commissioned as a part of the off-line tuning system of WITCH. The RFQ is coupled to the existing surface ionization ion source providing high intensity ion bunches (up to 107 ions per bunch) towards the pulsed drift tube and the Penning traps of WITCH. This achievement allows for loading and tuning of the Penning traps in the domain of space charge limits and grants off-line operation independently of the REX-ISOLDE ion source. The current upgrade allows for a more thorough and frequent testing with bunched stable ion beams of high intensities, which will be used for studying various systematic effects involved in experiments with radioactive ions. [Copyright &y& Elsevier]

The article offers the author's insights on the modality and parity of weak interactions. The author states that the beta decay is one of the manifestations of the weak interactions, which is one of the four fundamental forces in nature. He relates that the weak interactions is unique in breaking the symmetry of mirror reflection. He mentions that a mirror world that does not owe its reality to ignorance either logical or physical, which indicates that the explanations preserve symmetries.

No abstract received. [ABSTRACT FROM AUTHOR]

Abstract: We present a case study on a new type of beam station for the measurement of angular correlations in the β-decay of free neutrons. This beam station, called proton and electron radiation channel (PERC), is a cold-neutron guide that delivers at its open end, instead of neutrons, a beam of electrons and protons from neutron decays that take place far inside the guide. These charged neutron-decay products are magnetically guided to the end of the neutron guide, where they are separated from the cold-neutron beam. In this way, a general-purpose source of neutron decay products is obtained which can be operated as a user facility for a variety of different experiments in neutron decay correlation spectroscopy that may be installed at this beam station. The angular distribution of the emitted charged particles depends on the magnetic field configuration and can be chosen freely, according to the need of the experiment being carried out. A gain in phase space density of several orders of magnitude can be achieved with PERC, as compared to existing neutron decay spectrometers. Detailed calculations show that the spectra and angular distributions of the emerging electrons and protons will be distortion- and background-free on the level of 10−4, more than 10 times better than that achieved today. [Copyright &y& Elsevier]

Neutrinos have recently provided us with the first tangible evidence of phenomena beyond the reach of our theory of the laws of particle physics, the remarkably predictive “Standard Model”. The positive observation of oscillations in atmospheric and in solar neutrinos gives new motivations for more sensitive searches. Unfortunately, the oscillation experiments can only provide data on the squared mass differences of the neutrino mass eigenstates, while the absolute scale can only be obtained from direct mass measurements, 3H end point measurements for example or, in the case of Majorana neutrinos, more sensitively by neutrinoless double beta decay. In fact, recently published constraints on the mixing angles of the neutrino mixing matrix make a strong case that if neutrinos are Majorana particles, there are many scenarios in which next-generation double beta decay experiments should be able to observe the phenomenon, trying to disentangle the mass scale of the neutrinos. The interest for next-generation double beta decay experiments is growing, for if the mass scale is below ∼ 0.2eV, double beta decay may be the only hope for measuring it. [ABSTRACT FROM AUTHOR]

We analyze the B → ππ, π K modes in the light of the most recent B-factory data, and obtain the following new results: (i) the $B^0_d\to\pi^ + \pi^-,\pi^- K^ + $ modes prefer γ = (74±6)°, which - together with |V ub / V cb | - allows us to determine the "true" unitarity triangle and to search for CP-violating new-physics contributions to B 0 d - $\bar B^0_d$ mixing; (ii) the B → π K puzzle reflected in particular by the low experimental value of the ratio R n of the neutral B → π K rates persists and still favors new physics in the electroweak penguin sector with a new CP-violating phase ϕ ~ –90°, although now also ϕ ~ +90° can bring us rather close to the data; (iii) the mixing-induced $B^0_d\to\pi^0 K_{\mathrm {S}}$ CP asymmetry is a sensitive probe of the sign of this phase, and would currently favor ϕ ~ +90°, as well as the direct CP asymmetry of $B^\pm\to\pi^0K^\pm$ , which suffers, however, from large hadronic uncertainties; (iv) we investigate the sensitivity of our B → π K analysis to large non-factorizable SU(3)-breaking effects and find that their impact is surprisingly small so that it is indeed exciting to speculate on new physics; (v) assuming that new physics enters through Z 0 penguins, we study the interplay between B → π K and rare B, K decays and point out that the most recent B-factory constraints for the latter have interesting implications, bringing us to a few scenarios for the future evolution of the data, where also the mixing-induced CP violation in $B^0_d\to\pi^0 K_{\mathrm {S}}$ plays a prominent rôle. [ABSTRACT FROM AUTHOR]

Abstract: I provide a personal overview of the 2008, International Workshop on Particle Physics with Slow Neutrons. [Copyright &y& Elsevier]

Abstract: We present the new large neutron decay spectrometer Perkeo III designed to study neutron -decay in-beam. It offers largely improved statistics over its predecessor Perkeo II. When used with a pulsed neutron beam, leading sources of systematic errors in other experiments are strongly suppressed or eliminated. The instrument was commissioned in a first run at the high flux reactor of the Institut Laue-Langevin, Grenoble. With a continuous polarized neutron beam, a neutron decay rate of was obtained. [Copyright &y& Elsevier]

We summarise the most recent results of the Belle experiment about flavour changing neutral current (FCNC) radiative and (semi-) leptonic B decays. In particular, we report about the first observation of the decays B → K*ℓ+ℓ-, B → ØØKγ, the inclusive B → Xsℓ+ℓ-. We also report about searches for B → ℓ+ℓ- decay and for CP asymmetries in B → K*γ. [ABSTRACT FROM AUTHOR]

The author shares his memories of working with the Indian theoretical physicist E. C. George Sudarshan. Topics discussed include information on the theory of weak interactions; discussions on the relative weakness of strangeness-changing beta decays; and the information on the contribution of Sudarshan to physics such as quantum optics, primordial nucleosynthesis and formal field theory.