The observation of gravitational waves from an asymmetric binary opens the possibility for heavy neutron stars, but these pose challenges to models of the neutron star equation of state. We construct ...heavy neutron stars by introducing nontrivial structure in the speed of sound sourced by deconfined QCD matter, which cannot be well recovered by spectral representations. Their moment of inertia, Love number, and quadrupole moment are very small, so a tenfold increase in sensitivity may be needed to test this possibility with gravitational waves, which is feasible with third generation detectors.
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Mirror sectors have been proposed to address the problems of dark matter, baryogenesis, and the neutron lifetime anomaly. In this work we study a new, powerful probe of mirror neutrons: neutron star ...temperatures. When neutrons in the neutron star core convert to mirror neutrons during collisions, the vacancies left behind in the nucleon Fermi seas are refilled by more energetic nucleons, releasing immense amounts of heat in the process. We derive a new constraint on the allowed strength of neutron-mirror-neutron mixing from observations of the coldest (sub-40 000 Kelvin) neutron star, PSR 2144 − 3933 . Our limits compete with laboratory searches for neutron-mirror-neutron transitions but apply to a range of mass splittings between the neutron and mirror neutron that is 19 orders of magnitude larger. This heating mechanism, also pertinent to other neutron disappearance channels such as exotic neutron decay, provides a compelling physics target for upcoming ultraviolet, optical, and infrared telescopes to study thermal emissions of cold neutron stars.
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Innovations in small‐angle X‐ray and neutron scattering (SAXS and SANS) at major X‐ray and neutron facilities offer new characterization tools for researching materials phenomena relevant to advanced ...applications. For SAXS, the new generation of diffraction‐limited storage rings, incorporating multi‐bend achromat concepts, dramatically decrease electron beam emittance and significantly increase X‐ray brilliance over previous third‐generation sources. This results in intense X‐ray incident beams that are more compact in the horizontal plane, allowing significantly improved spatial resolution, better time resolution, and a new era for coherent‐beam SAXS methods such as X‐ray photon correlation spectroscopy. Elsewhere, X‐ray free‐electron laser sources provide extremely bright, fully coherent, X‐ray pulses of <100 fs and can support SAXS studies of material processes where entire SAXS data sets are collected in a single pulse train. Meanwhile, SANS at both steady‐state reactor and pulsed spallation neutron sources has significantly evolved. Developments in neutron optics and multiple detector carriages now enable data collection in a few minutes for materials characterization over nanometre‐to‐micrometre scale ranges, opening up real‐time studies of multi‐scale materials phenomena. SANS at pulsed neutron sources is becoming more integrated with neutron diffraction methods for simultaneous structure characterization of complex materials. In this paper, selected developments are highlighted and some recent state‐of‐the‐art studies discussed, relevant to hard matter applications in advanced manufacturing, energy and climate change.
Selected recent advances in small‐angle X‐ray and neutron scattering are highlighted, together with some of the hard material applications they serve in the areas of manufacturing, energy and climate change. This paper is associated with work presented at the 18th International Conference on Small‐Angle Scattering, Campinas, Brazil, September 2022 (SAS 2022).
Boron neutron capture therapy (BNCT), advanced cancer treatment utilizing nuclear fission of
B atom in cancer cells, is attracting increasing attention. As
B delivery agent, sodium borocaptate (
BSH,
...B
H
SH ⋅ 2Na), has been used in clinical studies along with L-boronophenylalanine. Recently, this boron cluster has been conjugated with lipids, polymers or nanoparticles to increase selectivity to and retentivity in tumor. In this work, anticancer nanoformulations for BNCT are designed, consisting of poly(glycerol) functionalized detonation nanodiamonds (DND-PG) as a hydrophilic nanocarrier, the boron cluster moiety (
B
H
) as a dense boron-10 source, and phenylboronic acid or RGD peptide as an active targeting moiety. Some hydroxy groups in PG were oxidized to carboxy groups (DND-PG-COOH) to conjugate the active targeting moiety. Some hydroxy groups in DND-PG-COOH were then transformed to azide to conjugate
B
H
through click chemistry. The nanodrugs were evaluated in vitro using B16 murine melanoma cells in terms of cell viability, BNCT efficacy and cellular uptake. As a result, the
B
H
moiety is found to facilitate cellular uptake probably due to its negative charge. Upon thermal neutron irradiation, the nanodrugs with
B
H
moiety exhibited good anticancer efficacies with slight differences with and without targeting moiety.
A new nuclear research reactor, the Jordan Research and Training Reactor (JRTR), has completed its hot commissioning testing and is awaiting the issuance of its operation license. The JRTR is the ...first nuclear reactor to be constructed in Jordan. The JRTR reached its first criticality on April 25th, 2016 and is currently undergoing initial operational testing up to its full rated power. The JRTR is an open-tank-in-pool multi-purpose research reactor with a maximum rated power of 5 MWt, upgradable to 10 MWt, and thermal neutron fluxes of order of 1014 n/cm2. sec in the core region and 1013 n/cm2. sec in the reflector region. The JRTR will provide the following multi-purpose services, both domestically and internationally: education and training, neutron activation analysis, radioisotope production, material irradiation including neutron transmutation doping and various neutron beam research such as in terms of neutron imaging and neutron scattering. In this paper, the general characteristics of the JRTR and its utilization aspects are introduced. Perspectives on the instrumentation plan of the neutron beam tubes of the JRTR are proposed. Having the JRTR to be the first regional scientific research center of excellence in the Middle-East for education, training, and research in nuclear technology applications is highlighted.
•The UUTR neutron radiography capability is computationally examined regarding the design of tri-layered neutron beamstop prototype intended to be utilized for both imaging and shielding ...purposes.•Augmentations are used to increase computational efficiency in MCNP6 simulations for deeply-penetrating shielding problems by employing adjoint-SN computed weight windows following the CADIS method.•Neutron responses in tally regions of importance within the beamstop design between CADIS-MCNP6 and PENTRAN are in good agreement and differ by less than 8%.
A new neutron radiography facility for the University of Utah TRIGA Reactor (UUTR) is computationally designed to support a multi-purpose irradiation and imaging chamber with a terminal beamstop. Previous efforts from a 3-D MCNP6 UUTR neutron beamport simulation reveals an available neutron flux of 2.5 × 107 ± 1.4 × 105n/cm2/s with an associated dose rate of 5.0 × 105 ± 2.8 × 103 mrem/hr at the end of the beamline system. The shielding required to attenuate the neutron beam and other secondary radiation from reaching the surrounding environment during radiography experiments has been assessed and implemented into MCNP6 Monte Carlo and PENTRAN SN transport code models to assess shield performance and directly compare response solutions between the two methods. In addition, the neutron importance function obtained from adjoint-SN transport is utilized to optimize calculation efficiency in a weight window accelerated PENTRAN-CADIS-MCNP6 model of the irradiation chamber beamstop. Good agreement between adjoint-SN and PENTRAN-CADIS-MCNP6 dose rate calculations is achieved, yielding predicted detector responses within an 8% difference in tally regions of importance. The total neutron dose rate is estimated throughout the entirety of the beamstop prototype, where recommended dimensions and material compositions of the shielding apparatus are provided with supporting analysis.
Following the discovery of the gravitational-wave source GW170817 by three Laser Interferometer Gravitational-wave Observatory (LIGO)/Virgo antennae (Abbott et al., 2017a), the MASTER Global Robotic ...Net telescopes obtained the first image of the NGC 4993 host galaxy. An optical transient, MASTER OTJ130948.10-232253.3/SSS17a was later found, which appears to be a kilonova resulting from the merger of two neutron stars (NSs). Here we describe this independent detection and photometry of the kilonova made in white light, and in B, V, and R filters. We note that the luminosity of this kilonova in NGC 4993 is very close to those measured for other kilonovae possibly associated with gamma-ray burst (GRB) 130603 and GRB 080503.
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