skip to main content

Title: The development of the NNBAR experiment
Abstract The NNBAR experiment for the European Spallation Source will search for free neutrons converting to antineutrons with a sensitivity improvement of three orders of magnitude compared to the last such search. This paper describes progress towards a conceptual design report for NNBAR. The design of a moderator, neutron reflector, beamline, shielding and annihilation detector is reported. The simulations used form part of a model which will be used for optimisation of the experiment design and quantification of its sensitivity.  more » « less
Award ID(s):
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more » ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; « less
Date Published:
Journal Name:
Journal of Instrumentation
Page Range / eLocation ID:
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. Abstract The nEXO neutrinoless double beta (0 νββ ) decay experiment is designed to use a time projection chamber and 5000 kg of isotopically enriched liquid xenon to search for the decay in 136 Xe. Progress in the detector design, paired with higher fidelity in its simulation and an advanced data analysis, based on the one used for the final results of EXO-200, produce a sensitivity prediction that exceeds the half-life of 10 28 years. Specifically, improvements have been made in the understanding of production of scintillation photons and charge as well as of their transport and reconstruction in the detector. The more detailed knowledge of the detector construction has been paired with more assays for trace radioactivity in different materials. In particular, the use of custom electroformed copper is now incorporated in the design, leading to a substantial reduction in backgrounds from the intrinsic radioactivity of detector materials. Furthermore, a number of assumptions from previous sensitivity projections have gained further support from interim work validating the nEXO experiment concept. Together these improvements and updates suggest that the nEXO experiment will reach a half-life sensitivity of 1.35 × 10 28 yr at 90% confidence level in 10 years of data taking, covering the parameter space associated with the inverted neutrino mass ordering, along with a significant portion of the parameter space for the normal ordering scenario, for almost all nuclear matrix elements. The effects of backgrounds deviating from the nominal values used for the projections are also illustrated, concluding that the nEXO design is robust against a number of imperfections of the model. 
    more » « less
  2. Long-lived particles (LLPs) show up in many extensions of the Standard Model, but they are challenging to search for with current detectors, due to their very displaced vertices. This study evaluated the ability of the trigger algorithms used in the Large Hadron Collider beauty (LHCb) experiment to detect long-lived particles and attempted to adapt them to enhance the sensitivity of this experiment to undiscovered long-lived particles. A model with a Higgs portal to a dark sector is tested, and the sensitivity reach is discussed. In the LHCb tracking system, the farthest tracking station from the collision point is the scintillating fiber tracker, the SciFi detector. One of the challenges in the track reconstruction is to deal with the large amount of and combinatorics of hits in the LHCb detector. A dedicated algorithm has been developed to cope with the large data output. When fully implemented, this algorithm would greatly increase the available statistics for any long-lived particle search in the forward region and would additionally improve the sensitivity of analyses dealing with Standard Model particles of large lifetime, such as K S 0 or Λ 0 hadrons. 
    more » « less
  3. The Beamforming Elevated Array for COsmic Neutrinos (BEACON) is a concept for a neutrino telescope designed to detect radio emission from upgoing air showers induced by tau leptons that are generated by ultra-high energy tau neutrino interactions in the Earth. This detection mechanism provides a pure measurement of the tau flavor of cosmogenic and astrophysical neutrinos, which could be used to set limits on the observed flavor ratios in a manner complimentary to the all-flavor neutrino flux measurements made by other experiments. A BEACON prototype has been installed at high elevation at Barcroft Field Station for several years and consists of 4 crossed-dipole antennas operating in the 30-80 MHz band and connected to a custom DAQ. The BEACON prototype is at high elevation to maximize effective volume and uses a directional beamforming trigger to reduce man-made background signals at the trigger level. This prototype system is expected to be capable of detecting downgoing cosmic ray air showers, a signal like the upgoing tau lepton air shower, but distinguishable chiefly by arrival direction. Here we give an overview of the BEACON experiment and present an ongoing cosmic ray search with data from the BEACON prototype. Cosmic ray candidates that are identified by this search will be used to experimentally determine the sensitivity of the BEACON concept to the known cosmic ray flux, which can then be used to predict the sensitivity of a full-scale BEACON array to the cosmogenic and astrophysical neutrino fluxes. 
    more » « less
  4. null (Ed.)
    A bstract The two kaon factories, KOTO and NA62, are at the cutting edge of the intensity frontier, with an unprecedented numbers of long lived and charged Kaons, ∼ 10 13 , being measured and analyzed. These experiments have currently a unique opportunity to search for dark sectors. In this paper, we demonstrate that searches done at KOTO and NA62 are complementary, both probing uncharted territories. We consider two qualitatively different physics cases. In the first, we analyze models of axion-like-particles (ALP) which couple to gluons or electroweak gauge bosons. In the second, we introduce a model based on an approximate strange flavor symmetry that leads to a strong violation of the Grossman-Nir bound. For the first scenario, we design a new search strategy for the KOTO experiment, K L → π 0 a → 4 γ . Its expected sensitivity on the branching ratio is at the level of 10 − 9 . This demonstrates the great potential of KOTO as a discovery machine. In addition, we revisit other bounds on ALPs from Kaon factories, highlighting the main sources of theoretical uncertainty, and collider experiments, and show new projections. For the second scenario, we show that the model may be compatible with the preliminary analysis of the KOTO-data that shows a hint for New Physics. 
    more » « less
  5. Abstract The TAROGE-M radio observatory is a self-triggered antenna array on top of the ∼2700 m high Mt. Melbourne in Antarctica, designed to detect impulsive geomagnetic emission from extensive air showers induced by ultra-high energy (UHE) particles beyond 10 17 eV, including cosmic rays, Earth-skimming tau neutrinos, and particularly, the “ANITA anomalous events” (AAE) from near and below the horizon. The six AAE discovered by the ANITA experiment have signal features similar to tau neutrinos but that hypothesis is in tension either with the interaction length predicted by Standard Model or with the flux limits set by other experiments. Their origin remains uncertain, requiring more experimental inputs for clarification. The detection concept of TAROGE-M takes advantage of a high altitude with synoptic view toward the horizon as an efficient signal collector, and the radio quietness as well as strong and near vertical geomagnetic field in Antarctica, enhancing the relative radio signal strength. This approach has a low energy threshold, high duty cycle, and is easy to extend for quickly enlarging statistics. Here we report experimental results from the first TAROGE-M station deployed in January 2020, corresponding to approximately one month of livetime. The station consists of six receiving antennas operating at 180–450 MHz, and can reconstruct source directions of impulsive events with an angular resolution of ∼0.3°, calibrated in situ with a drone-borne pulser system. To demonstrate TAROGE-M's ability to detect UHE air showers, a search for cosmic ray signals in 25.3-days of data together with the detection simulation were conducted, resulting in seven identified candidates. The detected events have a mean reconstructed energy of 0.95 -0.31 +0.46 EeV and zenith angles ranging from 25° to 82°, with both distributions agreeing with the simulations, indicating an energy threshold at about 0.3 EeV. The estimated cosmic ray flux at that energy is 1.2 -0.9 +0.7 × 10 -16 eV -1 km -2 yr -1 sr -1 , also consistent with results of other experiments. The TAROGE-M sensitivity to AAEs is approximated by the tau neutrino exposure with simulations, which suggests comparable sensitivity as ANITA's at around 1 EeV energy with a few station-years of operation. These first results verified the station design and performance in a polar and high-altitude environment, and are promising for further discovery of tau neutrinos and AAEs after an extension in the near future. 
    more » « less