| |
Torres-Sanchez, P., Babiano-Suarez, V., Correa, J. B., Gameiro, B., Lerendegui-Marco, J., Ladarescu, I., et al. (2026). First experimental demonstration of Compton imaging of 10B at clinical concentrations for real-time dosimetry in BNCT. Phys. Med. Biol., 71(16), 165030–17pp.
Abstract: Objective. Boron neutron capture therapy (BNCT) requires accurate knowledge of the boron distribution during treatment to enable reliable dosimetry and treatment verification. Compton imaging of the 478 keV prompt gamma rays emitted following neutron capture by 10B has been proposed as a promising technique for real-time boron monitoring. This work aims to experimentally evaluate the feasibility of Compton imaging under clinically relevant boron concentrations and realistic neutron-induced background conditions. Approach. A dedicated experimental campaign was performed at the Institut Laue-Langevin (ILL, Grenoble, France) using the i-TED Compton camera array. Three experimental configurations with progressively increasing neutron-induced background were investigated, including a water phantom containing 65 ppm 10B, representative of typical tumor concentrations during BNCT. Experimental measurements were complemented by detailed Geant4 Monte Carlo simulations to interpret detector performance, identify current limitations, and assess potential detector improvements. Main results. The experiments demonstrate, for the first time, Compton imaging of 10B at a clinically relevant concentration of 65 ppm under neutron irradiation. The reconstructed 478 keV gamma-ray emission was correctly localized with a spatial resolution of 22 mm (FWHM) and a signal-to-background ratio of 6.4. The study also identifies the principal limitations affecting detector performance, namely high count-rate effects and contamination from back-scattered Compton events. Dedicated analyses and simulations show that optimized event filtering substantially mitigates image degradation, while future detector developments based on pixelated scintillator arrays and improved timing capabilities are expected to significantly enhance performance under BNCT operating conditions. Significance. These results constitute the first experimental validation of Compton imaging for boron monitoring at clinically relevant concentrations and demonstrate the potential of the technique for real-time BNCT dosimetry. The identified detector improvements provide a technically grounded pathway towards clinical implementation of gamma-ray imaging-based dose monitoring in BNCT.
|
|
Barenboim, G., Ireland, A., & Stebbins, A. (2026). Constraints on Large-Scale White Noise in the Cosmic Density Field. Phys. Rev. Lett., 137(8), 081003–6pp.
Abstract: We present observational constraints on large-scale white noise (LSWN) in the cosmic density field, a phenomenon predicted to arise from nonlinear mode coupling during cosmological evolution. Building on the theoretical framework of our companion paper, where we demonstrated that nonlinearities inevitably redistribute power from small to large scales through mode mixing, we confront these predictions with current cosmological data. We modify the CLASS Boltzmann code to incorporate a white noise component kBH/k in the primordial power spectrum and perform parameter estimation using current cosmological data. The nondetection of excess power on the largest observable scales places stringent upper bounds: kBH <= 1.80 & times; 10-13 Mpc-1 at 99% confidence. These constraints imply the primordial power spectrum must deviate from a power law on small scales, perhaps with a sharp cutoff at kcut 0.03 pc-1 or through running of the spectral index with alpha s-0.019. Our results demonstrate that LSWN provides a powerful probe of the primordial spectrum at scales orders of magnitude smaller than those directly observable, offering unique constraints on early-universe physics.
|
|
n_TOF Collaboration(Balibrea-Correa, J. et al), Lerendegui-Marco, J., Domingo-Pardo, C., Babiano-Suarez, V., & Ladarescu, I. (2026). First 94Nb(n; γ) Measurement: Constraining the Nucleosynthetic Origin of 94Mo in Presolar Grains. Phys. Rev. Lett., 137(8), 082701–8pp.
Abstract: Isotopic measurements of presolar silicon carbide grains from dying stars have revealed a puzzling overabundance of 94Mo that stellar nucleosynthesis models have failed to reproduce for two decades. This discrepancy challenged our understanding of the slow neutron-capture process (s-process) that forges approximately half of the elements heavier than iron. The key uncertainty lies at 94Nb, a radioactive branching point where competition between neutron capture and beta decay governs the 94Mo production, yet the neutron-capture cross section had never been measured. Here, we report the first experimental determination of the 94Nb(n; gamma)95Nb cross section important for Mo isotopic abundances. The measurement was enabled by a coordinated effort involving high-purity target preparation at Institute of Solid State and Materials Research Dresden, radioactive sample production at the Institut Laue-Langevin Grenoble, radiochemical characterization at Paul Scherrer Institut Villigen, and the time-of-flight CERN n_TOF facility using for the first time segmented total-energy detectors. Incorporation of the resulting Maxwellianaveraged cross section into fully coupled nucleosynthesis models of low-mass asymptotic giant-branch stars brings them into agreement with the presolar grain data. These results remove a major nuclear-physics input uncertainty at the 94Nb branching point and provide a firmer foundation for understanding the origin of 94Mo in the Solar System.
|
|
ATLAS Collaboration(Aad, G. et al), Ahuja, S., Aikot, A., Cabrera Urban, S., Cantero, J., Carrion Martinez, C., et al. (2026). Combined effective field theory interpretation of measurements sensitive to quartic gauge boson couplings in pp collisions at √s=13 TeV with the ATLAS detector. Phys. Lett. B, 879, 140683–19pp.
Abstract: A combination of measurements sensitive to anomalous quartic electroweak gauge boson couplings is presented using proton-proton collision data collected by the ATLAS detector at root s = 13 TeV at the LHC. Contributing analyses include measurements of vector-boson scattering in numerous final states as well as a tri-boson measurement. The combined measurement is used to constrain anomalous electroweak boson quartic self-couplings that result from dimension-8 operators in the Eboli model using an effective field theory. Results are presented as 68% and 95% confidence level intervals parameterised by one or two Wilson coefficients, both with and without unitarity constraints applied. Theoretical bounds from unitarity and positivity are overlaid where relevant. Confidence intervals obtained from simultaneous profiled fits to all Wilson coefficients are also presented.
|
|
ATLAS Collaboration(Aad, G. et al), Ahuja, S., Aikot, A., Amos, K. R., Bouchhar, N., Cabrera Urban, S., et al. (2026). Search for emerging jets in pp collisions at √s=13 TeV with the ATLAS experiment. Eur. Phys. J. C, 86(7), 808–32pp.
Abstract: A search is presented for emerging jets using 140 fb(-1) of proton-proton collision data at root s = 13 TeV, collected by the ATLAS experiment between 2015 and 2018. The search looks for the existence of a dark sector with symmetries similar to those in quantum chromodynamics. This dark sector is populated with dark quarks, which undergo showering similar to quarks in the Standard Model, leading to a high multiplicity of long-lived dark hadrons within a dark jet. These dark hadrons subsequently decay to Standard Model particles via a new heavy scalar mediating particle phi. This results in jets which containmultiple displaced vertices, known as emerging jets. This analysis targets four-jet topologies, with two emerging jets and two Standard Model jets, resulting from the decay of pair-produced scalar mediators. No significant excess above the StandardModel background is observed. For dark pion proper decay lengths of 20 mm, mediator masses are excluded between 1 and 2 TeV assuming a dark pion mass of 20 GeV.
|
|
|
