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At least 37 records · Page 2

ProtoDUNE-VD for Beyond the Standard Model Searches: Initial Studies and Future Prospects

The Deep Underground Neutrino Experiment (DUNE) is a next-generation long-baseline neutrino program designed to address fundamental questions in neutrino and astroparticle physics. ProtoDUNE, operating at the CERN Neutrino Platform, serves as a full-scale prototype for the DUNE Far Detector. In particular, the ProtoDUNE Vertical Drift (ProtoDUNE-VD) detector provides a powerful testbed for validating reconstruction and event selection techniques for future DUNE operations. In addition to detector R&D, ProtoDUNE enables a novel parasitic beam-dump search for beyond-the-Standard-Model (BSM) particles. However, it faces several challenges. Most notably, the ProtoDUNE-VD modules operate on the surface and are consequently exposed to an intense flux of cosmic rays, which requires a dedicated trigger. In addition, standard neutrinos are also produced in the T2 target area from the decay of unstable mesons, constituting a relevant background, which needs to be well understood and characterized a priori. We present the first studies based on 2025 data taken with a trigger designed to identify neutrino candidates at ProtoDUNE-VD. ProtoDUNE-VD’s high-resolution LArTPC imaging allows detailed reconstruction of decay and scattering signatures. This work demonstrates the complementarity of traditional tools such as Pandora and modern machine-learning approaches, providing key input for atmospheric neutrino and rare-event searches in the DUNE Vertical Drift program.

Bagdu, Halit [U. Iowa, Iowa City]↗

A Beamdump facility at Jefferson Lab

The potential of the intense secondary muon, neutrino, and (hypothetical) light dark matter beams at the Thomas Jefferson National Accelerator Facility (Jefferson Lab) is explored. These are produced in the high-power dumps with high-current electron beams. Light dark matter searches with the approved Beam Dump eXperiment (BDX) are driving the realization of a new underground vault behind Hall A that could be extended to a Beamdump Facility with little additional installations. High-energy muons created via the Bethe–Heitler process uniquely do not proceed through the more common pion production and decay channels. Several possible muon physics applications are highlighted. Neutrino detector technologies and experiments suitable for a beamdump facility are outlined.

Accelerator Physics↗

A survey of ultraviolet variability in blazars

This is the first comprehensive, consistent survey of the ultraviolet variability properties of a large sample of blazars. All of the 14 blazars with five or more observations in a single IUE camera showed significant variability. The strength of the ultraviolet variability is positively correlated with both the apparent ultraviolet luminosity and the degree of optical polarization of the source. This is the first clear indication that the ultraviolet continua of blazars are beamed. A search for rapid variability yielded nine 'events' with doubling time scales of 0.5-7 days. These rapid flux variations and correlations argue for the standard synchrotron self-Compton model, and against the accretion disk model, which would predict slower variations and the opposite sense of correlation.

Edelson, Rick↗

A US coordination Facility for the Spectrum-X-Gamma Observatory

We have completed our efforts in support of the Spectrum X Gamma mission under a NASA grant. These activities have included direct support to the mission, developing unifying tools applicable to SXG and other X-ray astronomy missions, and X-ray astronomy research to maintain our understanding of the importance and relevance of SXG to the field. SXG provides: 1) Simultaneous Multiwavelength Capability; 2) Large Field of View High Resolution Imaging Spectroscopy; 3) Sensitive Polarimetry with SXRP (Stellar X-Ray Polarimeter). These capabilities will ensure the fulfillment of the following objectives: understanding the accretion dynamics and the importance of reprocessing, upscattering, and disk viscosity around black holes; studying cluster mergers; spatially resolving cluster cooling flows to detect cooling gas; detecting cool gas in cluster outskirts in absorption; mapping gas in filaments around clusters; finding the 'missing' baryons in the Universe; determining the activity history of the black hole in the Galactic Center of our own central black hole; determining pulsar beam geometry; searching for the Lense-Thirring effect in black hole sources; constraining emission mechanisms and accretion geometry in AGN.

Forman, W.↗

Localization of Binary Black Hole Mergers with Known Inclination

The localization of stellar-mass binary black hole mergers using gravitational waves is critical in understanding the properties of the binaries' host galaxies, observing possible electromagnetic emission from the mergers, or using them as a cosmological distance ladder. The precision of this localization can be substantially increased with prior astrophysical information about the binary system. In particular, constraining the inclination of the binary can reduce the distance uncertainty of the source. Here we present the first realistic set of localizations for binary black hole mergers, including different prior constraints on the binaries' inclinations. We find that prior information on the inclination can reduce the localization volume by a factor of 3. We discuss two astrophysical scenarios of interest: (i) follow-up searches for beamed electromagnetic/neutrino counterparts and (ii) mergers in the accretion disks of active galactic nuclei.

Corley, K. Rainer↗

Developing New Beam Constraints to Improve Sterile Neutrino Searches at NOvA

NOvA is a long-baseline neutrino oscillation experiment utilizing two functionally identical liquid scintillator detectors located 14 mrad off-axis from the NuMI beam at Fermilab. The position of the Near Detector (ND), 1 km from the neutrino production target, means it sees a range of off-axis angles (12.6-17.2 mrad), resulting in a noticeable energy gradient across the detector face. In addition, the neutrino production points vary widely along the decay pipe, which leads to a distribution of true neutrino baselines (L), and limits the sensitivity of our current sterile neutrino searches. This work presents a new "baseline reconstruction" technique designed to exploit our off-axis position to triangulate the precise origin of neutrinos within the NuMI beamline. By projecting the total momentum vector of Charged Current (CC) and Neutral Current (NC) interactions back to the central beam axis, we estimate the individual baseline for each event. We describe the technique, evaluate its performance, and demonstrate how this can improve the sensitivity of future searches for sterile neutrinos through reduced flux systematic uncertainties and improved L/E resolution.

Burns, Jessica [Cincinnati U.]↗

First evaluation of meson and τ lepton spectra and search for heavy neutral leptons at ILC beam dump

A beam dump experiment can be seamlessly added to the proposed Inter- national Linear Collider (ILC) program because the high energy electron beam should be dumped after the collision point. The ILC beam dump experiment will provide an excellent opportunity to search for new long-lived particles. Since many of them can be produced by a rare decay of standard model particles, we evaluate spectra of the mesons and τ lepton at the decay based on the PHITS and PYTHIA8 simulations. As a motivated physics case, we study the projected sensitivity of heavy neutral leptons at the ILC beam dump experiment. The heavy neutral leptons can also be produced via deep inelastic scattering and Z boson decay at the ILC main detector, which we include in the projection. With the multi-track signal, the reach would be greatly extended in mass and coupling, even compared with the other proposed searches.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Attenuation of Weather Radar Signals Due to Wetting of the Radome by Rainwater or Incomplete Filling of the Beam Volume

A search of scientific literature, both printed and electronic, was undertaken to provide quantitative estimates of attenuation effects of rainfall on weather radar radomes. The emphasis was on C-band (5 cm) and S-Band (10 cm) wavelengths. An empirical model was developed to estimate two-way wet radome losses as a function of frequency and rainfall rate for both standard and hydrophobic radomes. The model fits most of the published data within +/- 1 dB at both target wavelengths for rain rates from less than ten to more than 200 mm/hr. Rainfall attenuation effects remain under 1 dB at both frequencies regardless of radome type for rainfall rates up to 10 mm/hr. S-Band losses with a hydrophobic radome such as that on the WSR-88D remain under 1 dB up to 100 mm/hr. C-Band losses on standard radomes such as that on the Patrick AFB (Air Force Base) WSR-74C can reach as much as 5 dB at 50 mm/hr. In addition, calculations were performed to determine the reduction in effective reflectivity, Z, when a radar target is smaller than the sampling volume of the radar. Results are presented for both the Patrick Air Force Base WSR-74C and the WSR-88D as a function of target size and range.

Merceret, Francis J.↗

Constraining Cross Section and Beam Systematics for Future NOvA Sterile Neutrino Search

he NOvA (NuMI Off-axis $\nu_e$ Appearance) experiment measures neutrino oscillations in a nearly pure muon (anti)neutrino beam over a 810 km baseline. We search for sterile neutrino driven oscillations in both neutral current (NC) and charged current (CC) muon neutrino samples. A deficit of NC interactions at the Far Detector could occur since sterile neutrinos do not couple to the Z boson. A modulation of the muon neutrino disappearance probability is possible due to a new mass splitting. The NuMI beam line is capable of running in forward or reverse horn current modes, which creates a neutrino or antineutrino beam, respectively. Samples collected in forward horn current (FHC) or reverse horn current (RHC) modes are subject to beam optics uncertainties, in addition to cross section and hadron production uncertainties. We explore the ategories. To tackle reduction of cross section uncertainties, we study how splitting the neutral current (NC) samples can impact the systematic reduction and its implications on oscillation parameters, leveraging results from Monte Carlo simulations. Additionally, we look at the possibility of using a $\nu$-on-e scattering sample. The $\nu$-on-e scattering process has minimal cross section uncertainties compared to that of neutrino-nucleus interactions, which can help constrain the overall flux normalizations. Using both the ZHC sample, NC split sample, and $\nu$-on-e scattering sample jointly with FHC samples would reduce the focusing uncertainties and the hadron production uncertainties in the future sterile analysis.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

First search for sterile neutrino oscillation leading to $ν_μ$ disappearance in the Booster Neutrino Beam at ICARUS

We present a search for muon neutrino disappearance in the Booster Neutrino Beam (BNB) at Fermilab using the ICARUS detector. Neutrino interactions identified as muon neutrinos interacting with argon nuclei via the charged current interaction and having only a muon and at least one proton in the final state (1$μ$Np) have been selected from data collected in 2022-2023 (ICARUS Run 2) and compared with a simulation-based expectation. In the context of a fit to a two-neutrino approximation of the sterile 3+1 model, including the impact of systematic uncertainty from the flux, neutrino interaction, and detector models, we find no statistically significant muon neutrino disappearance at the ICARUS baseline of 600 meters from the BNB target. Corresponding 90% C.L. exclusion contours in $Δm^2_{41}$ - sin$^22θ_{μμ}$ space are presented. This is the first oscillation analysis produced by ICARUS exposed to the BNB. We note that the analysis is systematics limited due to large unconstrained uncertainties from the flux and interaction models. In future joint analyses, data from ICARUS and the SBND detector, exposed to the BNB at 110 meters from target, will be combined to provide significant constraint of these uncertainties, enabling a robust, world-leading two-detector analysis.

Alrahman, F. Abd [Houston U.]↗

Understanding the enhancement of scintillation light in xenon-doped liquid argon

Measuring the scintillation light in noble gases is an important detection technique in particle physics. Numerous rare event searches like neutrino beam experiments, neutrino-less double beta-decay, and dark matter searches use argon-based detectors. In liquid argon, the light yield can be enhanced by the addition of a small quantity of xenon, where ~10–1000 ppm are added. The general enhancement mechanism and its pathway via an energy transfer between argon and xenon excimers is well known, however the importance of absorption of argon excimer emission by atomic xenon has not been fully appreciated. This absorption significantly reduces the light yield in commercially available argon (extracted from air) which contains trace amounts (~0.1 ppm) of xenon. The addition of a small xenon dopant of ~10 ppm recovers this lost light resulting in an increased light yield over un-doped argon of about a factor of two. Here, in this paper, we introduce a model for the light production in xenon doped argon, including absorption and re-emission, and compare it to the measured time dependence of light emission in xenon-doped argon.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Search for a Long-Lived $\mu\mu$ Resonance in the NuMI Beam at ICARUS

The ICARUS detector in the Short-Baseline Neutrino program at Fermilab is sensitive to “long-lived” new physics particles that would be produced in the Neutrinos at the Main Injector (NuMI) beam and decay inside the ICARUS liquid argon time projection chamber (LArTPC). We show results from a new analysis in ICARUS which searched for di-muon decays from a long-lived particle produced in kaon decay in the NuMI beam. The search is sensitive to new areas of parameter space for the Higgs portal scalar and an axion-like particle model. The sensitivity is also presented in a model-independent way applicable to any new physics model predicting the process $K \to \pi+S(\to\mu\mu)$, for a long-lived particle S. This is the first search for new physics performed with the ICARUS detector at Fermilab. It paves the way for the future program of long-lived particle searches at ICARUS.

43 PARTICLE ACCELERATORS↗

First displaced vertex search for electroproduced dark-sector strongly interacting massive particles by the HPS experiment

The Heavy Photon Search experiment (HPS) is a fixed-target, electron beam experiment designed to search for 𝑒 + ⁢𝑒 − mass resonances and displaced decays using a forward acceptance spectrometer. This paper details the search for naturally long-lived “dark” vector mesons (𝑉 𝐷 ) arising from a dark sector of beyond-Standard-Model strongly interacting massive particles, characterized by a QCD-like 𝑆⁢𝑈⁢(3) 𝐷 symmetry and coupled to the Standard Model photon via a new 𝑈⁢(1) 𝐷 gauge interaction mediated by the “heavy photon,” or 𝐴′. The results are based on an integrated luminosity of 10 608 nb −1 collected during the 2016 HPS engineering run. The displaced vertex search for 𝑉 𝐷 → 𝑒 +⁢ 𝑒 − in the 𝑒 +⁢ 𝑒 − invariant mass range 39–179 MeV showed no statistically significant evidence for signal above the QED background.

extensions of gauge sector↗

Search for the chiral magnetic effect through beam energy dependence of charge separation using event shape selection

High-energy, heavy-ion collisions can create local domains of chirality-imbalanced quarks, reflecting the topological features of quantum chromodynamics. The chiral magnetic effect (CME) predicts an electric charge separation of quarks in such topological domains along the magnetic field ($\vec{B}$) generated by the passing of two high-Z nuclei. Here, we use a correlation observable Δ⁢𝛾$^{112}$ between charged meson pairs to detect the CME-induced charge separation and a novel event shape selection (ESS) method to mitigate the background effects related to elliptic flow (𝑣 2 ). The ESS method classifies events based on the emission pattern of final-state particles and determines Δ⁢𝛾$^{112}_{ESS}$ from the zero-flow limit. We reconstruct the $\vec{B}$ field direction from the spectator nucleons, which minimizes backgrounds unrelated to the collective motion of the system. In this work, we report the measurements of Δ⁢𝛾$^{112}$ and a background indicator Δ⁢𝛾$^{132}$ in Au+Au collisions from the Brookhaven National Laboratory Relativistic Heavy Ion Collider (RHIC) Beam Energy Scan phase II and at the top RHIC energy. After background suppression, Δ⁢𝛾$^{132}_{ESS}$ aligns with zero, and Δ⁢𝛾$^{112}_{ESS}$ is reduced to no more than 20% of Δ⁢𝛾$^{112}$. We observe a finite residual charge separation with 2.5⁢𝜎, 3⁢𝜎, and 3.2⁢𝜎 significance in the 20–50% centrality range of Au + Au collisions at 11.5, 14.6, and 19.6 GeV. The results at 17.3 and 27 GeV also show positive values but with a lower significance of 1.3⁢𝜎 and 1.1⁢𝜎, respectively. The corresponding Δ⁢𝛾$^{112}_{ESS}$ values at 7.7, 9.2, and 200 GeV are consistent with zero within uncertainties.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

Design and implementation of the new scintillation light detection system of ICARUS T600

ICARUS T600 is the far detector of the Short Baseline Neutrino program at Fermilab (U.S.A.), which foresees three Liquid Argon Time Projection Chambers along the Booster Neutrino Beam line to search for LSND-like sterile neutrino signal. The T600 detector underwent a significant overhauling process at CERN, introducing new technological developments while maintaining the already achieved performances. The realization of a new liquid argon scintillation light detection system is a primary task of the detector overhaul. As the detector will be subject to a huge flux of cosmic rays, the light detection system should allow the 3D reconstruction of events contributing to the identification of neutrino interactions in the beam spill gate. The design and implementation of the new scintillation light detection system of ICARUS T600 is described.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Investigation of low-energy particle remnants in high-energy collisions at the LHC with a skipper-CCD detector

We deployed the Mobile Skipper Testing Apparatus ∼33 m away from the Compact Muon Solenoid collision point, the first skipper-CCD detector probing low-energy particles produced in high-energy collisions at the Large Hadron Collider. In this work, we search for beam-related events using data collected in 2024 during beam-on and beam-off periods. The dataset corresponds to integrated luminosities of 113.3 fb −1 and 1.54 nb −1 for the proton-proton and Pb-Pb collision periods, respectively. We report observed event rates in a model-independent framework across two ionization regions: ≤ 20⁢𝑒 − and > 20⁢𝑒 − . For the low-energy region, we perform a likelihood analysis to test the null hypothesis of no beam-correlated signal. We found no significant correlation during proton-proton and Pb-Pb collisions. For the high-energy region, we present the energy spectra for both collision periods and compare event rates for images with and without luminosity. We observe a slight increase in the event rate following the Pb-Pb collisions, coinciding with a rise in the single-electron rate, which will be investigated in future work. Using the low-energy proton-proton results, we place 95% confidence level constraints on the mass-millicharge parameter space of millicharged particles. Overall, the results in this work demonstrate the viability of skipper-CCD technology to explore new physics at high-energy colliders and motivate future searches with more massive detectors.

Cervantes-Vergara, Brenda A. [Fermi National Accel↗