Hadronic showers transfer a relevant amount of their energy to electromagnetic subshowers. We show that the generation of "secondary" dark photons in these subshowers is significant and typically ...dominates the production at low dark photon masses. The resulting dark photons are however substantially less energetic than the ones originating from mesons decay. We illustrate this point both semianalytically and through Monte Carlo simulations. Existing limits on vector-mediator scenarios for light dark matter are updated with the inclusion of the new production processes.
Medium-energy electron beam-dump experiments provide an intense source of secondary muons. These particles can be used to search for muon-coupling light dark scalars that may explain the (g − 2)μ ...anomaly. We applied this idea to the SLAC E137 experiment deriving new exclusion limits and evaluated the expected sensitivity for the planned Jefferson Lab BDX experiment (in case of a null result report). The calculation is based on numerical simulations that include a realistic description of secondary muons generation in the dump, dark scalar production, propagation, and decay, and, finally, the decay product (electrons, positrons, or photons) interaction with the detector. For both experiments, exclusion limits were extended to cover a broader area in the scalar-to-muon coupling vs scalar mass parameter space. This study demonstrates that electron beam-dump experiments have an enhanced sensitivity to new physics in processes that are usually studied using proton beams.
A novel mechanism to produce and detect light dark matter in experiments making use of GeV electrons (and positrons) impinging on a thick target (beam dump) is proposed. The positron-rich environment ...produced by the electromagnetic shower allows us to produce an A^{'} via nonresonant (e^{+}+e^{-}→γ+A^{'}) and resonant (e^{+}+e^{-}→A^{'}) annihilation on atomic electrons. The latter mechanism, for some selected kinematics, results in a larger sensitivity with respect to limits derived by the commonly used A^{'}-strahlung. This idea, applied to beam-dump experiments and active beam-dump experiments, pushes down the current limits by an order of magnitude.
High-energy positron annihilation is a viable mechanism to produce dark photons (A′). This reaction plays a significant role in beam-dump experiments using multi-GeV electron beams on thick targets ...by enhancing the sensitivity to A′ production. The positrons produced by the electromagnetic shower can produce an A′ via nonresonant (e++e−→γ+A′) and resonant (e++e−→A′) annihilation on atomic electrons. For visible decays, the contribution of resonant annihilation results in a larger sensitivity with respect to limits derived by the commonly used A′-strahlung in certain kinematic regions. When included in the evaluation of the E137 beam-dump experiment reach, positron annihilation pushes the current limit on ϵ downwards by a factor of 2 in the range 33 MeV/c2<mA′<120 MeV/c2.
This paper describes the design and performance of a compact detector, BDX-MINI, that incorporates all features of a concept that optimized the detection of light dark matter in the MeV-GeV mass ...range produced by electrons in a beam dump. It represents a reduced version of the future BDX experiment expected to run at JLAB. BDX-MINI was exposed to penetrating particles produced by a 2.176 GeV electron beam incident on the beam dump of Hall A at Jefferson Lab. The detector consists of 30.5 kg of PbWO
4
crystals with sufficient material following the beam dump to eliminate all known particles except neutrinos. The crystals are read out using silicon photomultipliers. Completely surrounding the detector are a passive layer of tungsten and two active scintillator veto systems, which are also read out using silicon photomultipliers. The design was validated and the performance of the robust detector was shown to be stable during a six month period during which the detector was operated with minimal access.
Light dark matter searches with positrons Battaglieri, M.; Bianconi, A.; Bisio, P. ...
European physical journal. A, Hadrons and nuclei,
08/2021, Volume:
57, Issue:
8
Journal Article
Peer reviewed
Open access
We discuss two complementary strategies to search for light dark matter (LDM) exploiting the positron beam possibly available in the future at Jefferson Laboratory. LDM is a new compelling hypothesis ...that identifies dark matter with new sub-GeV “hidden sector” states, neutral under standard model interactions and interacting with our world through a new force. Accelerator-based searches at the intensity frontier are uniquely suited to explore it. Thanks to the high intensity and the high energy of the Continuous Electron Beam Accelerator Facility (CEBAF) beam, and relying on a novel LDM production mechanism via positron annihilation on target atomic electrons, the proposed strategies will allow us to explore new regions in the LDM parameters space, thoroughly probing the LDM hypothesis as well as more general hidden sector scenarios.
GEOCONTEXT AND CHCONTEXT GEOGRAPHIC INFORMATION IN CULTURAL HERITAGE
The international archives of the photogrammetry, remote sensing and spatial information sciences/International archives of the photogrammetry, remote sensing and spatial information sciences,
07/2018
Journal Article
Kohli P, Siver PA, Marsicano LJ, Hamer JS, Coffin AM. 2017. Assessment of long-term trends for management of Candlewood Lake, Connecticut, USA. Lake Reserve Manage. 00:00-00.
Candlewood Lake, the ...largest lake in Connecticut, is a pumped-storage reservoir formed in the 1920s for hydropower generation. Since its inception, the lake has experienced shifts in water quality coupled with watershed development and, in the 1980s, the introduction and spread of the invasive macrophyte, Myriophyllum spicatum. In response, a monitoring program to track water quality and a winter drawdown program to mitigate growth of M. spicatum were initiated in 1985. Recently it was suggested that the drawdown program exacerbated eutrophication of the lake. To test this hypothesis, statistical analyses of the long-term (1985 to 2012) database was conducted with a focus on trophic-related variables. We examined the database using principal component analysis (PCA) and multivariate singular spectrum analysis (MSSA). MSSA is an extension of PCA for multivariate time series data that accounts for both temporal and cross-sectional dependencies. We found no evidence that the trophic condition declined, or that the drawdowns have deteriorated the water quality. Instead, we found that lower TS, TSI
Chl
, and TS
SD
values corresponding with improved trophic conditions occurred in summers following deep drawdowns, while significantly higher values correlated with shallow and less effective drawdowns. Overall, there has been a modest improvement in the trophic condition over time, attributed to a combination of the winter drawdowns and management efforts. In contrast, a steady and significant increase in dissolved salts, likely due to enhanced use of road deicing treatments, was documented.
The POKERINO prototype Antonov, A.; Bisio, P.; Bondì, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
September 2024, 2024-09-00, Volume:
1066
Journal Article
Peer reviewed
Open access
The POKER (POsitron resonant annihilation into dark mattER) project aims to perform a missing-energy measurement employing a ∼ 100 GeV positron beam impinging on an active thick target. The beam ...interaction with this detector could produce feebly interacting massive particles, exiting from it undetected and carrying away a significant fraction of the primary positron energy. The crucial element of the POKER project is a high-resolution PbWO4 electromagnetic calorimeter employed as the active target. A prototype of this calorimeter, POKERINO, consists of a 3 × 3 matrix of PbWO4 crystals with a SiPM-based readout system. In the summer of 2023, the POKERINO’s response to high-energy particles was measured for the first time at the H8 beamline of the Super Proton Synchrotron (SPS) at CERN. This manuscript summarises the most important results obtained during the test beam of POKERINO at CERN, highlighting how this study influenced the perspectives of the POKER experimental effort.
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