arXiv subjects

Joakim Cederkäll

Publications and source records attributed to Joakim Cederkäll.

5 recordsLinked to original sources

arXiv2026

Glimpses of the X17 from coherent elastic neutrino nucleus scattering

We show that the process of Coherent Elastic neutrino (ν) Nucleus Scattering (CEνNS) at nuclear reactor experiments has significant sensitivity to the so-called X17 particle, which has been invoked to explain the ATOMKI anomaly, wherein electron-positron pairs emerging from a nuclear transition of excited Be-8, He-4 and C-12 nuclei are studied. Such a new state has potentially been identified as a spin-1 object, with axial-vector couplings and a mass around 16.7 MeV, hence, in the kinematic range accessible by the aforementioned experimental settings. Specifically, we fit CONUS+ and Dresden-II data and show that a robust statistical analysis renders these more compatible with the X17 hypothesis, in turn interfering with the Standard Model (SM), than with that of the latter alone. The same stays true when also adding COHERENT data from π+ decays at rest, singling out two regions of preferred couplings of the X17 to electron and muon neutrinos as well as nuclei.

hep-ph↗

arXiv2026

The X17 Existence Hinted at by Nuclear Reactor Neutrinos

We show that by exploiting the process of Coherent Elastic neutrino (v) Nucleus Scattering (CEvNS), neutrino measurements by nuclear reactor experiments appear to corroborate the evidence of the so-called X17 particle, which has been invoked to explain the ATOMKI anomaly. We base our analysis primarily on CONUS+ and Dresden-II data, which, when combined with CEvNS data from COHERENT and neutrino oscillation data from IceCube, single out a unique region of couplings to neutrinos and nuclei.

hep-ph↗

arXiv2025

Hunting the elusive $X17$ in CE$ν$NS at the ESS

The so-called $X17$ particle has been proposed in order to explain a very significant resonant behaviour (in both the angular separation and invariant mass) of $e^+e^-$ pairs produced during a nuclear transition of excited $^8$Be, $^4$He and $^{12}$C nuclei. Fits to the corresponding data point, as most probable explanation, to a spin-1 object, which is protophobic and has a mass of approximately 16.7 MeV, which then makes the $X17$ potentially observable in Coherent Elastic neutrino ($ν$) Nucleus Scattering (CE$ν$NS) at the European Spallation Source (ESS). By adopting as theoretical framework a minimal extension of the Standard Model (SM) with a generic $U(1)'$ gauge group mixing with the hypercharge one of the latter, which can naturally accommodate the $X17$ state compliant with all available measurements from a variety of experiments, we predict that CE$ν$NS at the ESS will constitute an effective means to probe this hypothesis, even after allowing for the inevitable systematics associated to the performance of the planned detectors therein.

hep-ph↗

arXiv2021

The ESS neutrino super-beam near detector

The ESS Neutrino Super-Beam (ESSnuSB) is a proposed long-baseline neutrino oscillation experiment, performed with a high-intensity neutrino beam, to be developed as an extension to the European Spallation Source proton linac currently under construction in Lund, Sweden. The neutrinos would be detected with the near and far detectors of the experiment, the former within several hundred meters of the neutrino production point and the latter within several hundred kilometers. The far detector will consist of a megaton-scale water-Cherenkov detector, and the near detector will consist of a kiloton-scale water-Cherenkov detector in combination with a fine-grained tracking detector and an emulsion detector. The purpose of the near detector is to constrain the flux of the neutrino beam as well as to extract the electron-neutrino interaction cross-section in water, which requires high-performance energy reconstruction and particle flavor identification techniques. These measurements are crucial for the neutrino oscillation measurements that will be conducted using the far detector. Year 2021 sees the finalization of the conceptual design of the near detector after a thorough evaluation of the performance of a number of different design options, and a characterization of the neutrino reconstruction and flavor identification performances. In this talk we report on thesestudies.

hep-ex↗

arXiv2017

Towards an Experimental Determination of the Transition Strength Between the Ground States of $^{20}$F and $^{20}$Ne

Electron capture on $^{20}$Ne is thought to play a crucial role in the final evolution of electron-degenerate ONe stellar cores. Recent calculations suggest that the capture process is dominated by the second-forbidden transition between the ground states of $^{20}$Ne and $^{20}$F, making an experimental determination of this transition strength highly desirable. To accomplish this task we are refurbishing an intermediate-image magnetic spectrometer capable of focusing 7 MeV electrons, and designing a scintillator detector surrounded by an active cosmic-ray veto shield, which will serve as an energy-dispersive device at the focal plane.

physics.ins-det↗