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, Letnik:
57, Številka:
8
Journal Article
Recenzirano
Odprti dostop
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.
Mucosa-associated lymphoid tissue (MALT) lymphomas are known to occur in Sjögren syndrome (SS) patients, but reported cases in labial salivary glands (LSG) are rare. We report a case of 60-year-old ...female patient with SS who developed MALT lymphoma in the labial salivary glands during a 2-year time interval when she was participating in the Sjögren's International Clinical Collaborative Alliance, an ongoing longitudinal multisite observational study funded by the National Institutes of Health of the United States. At follow-up exam, LSG biopsy showed atypical diffuse infiltration by mononuclear cells of variable size and atypical nuclei affecting the whole specimen with destruction of glandular architecture, leading to a diagnosis of B-cell MALT lymphoma. Computerized tomography and bone marrow biopsy failed to show additional evidence of disease. Clinical, serologic, ocular, histologic and immunohistochemical findings are presented. A "watch and wait" policy was adopted with regular examinations.
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, Letnik:
1066
Journal Article
Recenzirano
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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.
The search for new comparably light (well below the electroweak scale) feebly interacting particles is an exciting possibility to explain some mysterious phenomena in physics, among them the origin ...of Dark Matter. The sensitivity study through detailed simulation of projected experiments is a key point in estimating their potential for discovery.
Several years ago we created the DMG4 package for the simulation of DM (Dark Matter) particles in fixed target experiments. The natural approach is to integrate this simulation into the same program that performs the full simulation of particles in the experiment setup. The Geant4 toolkit framework was chosen as the most popular and versatile solution nowadays.
The simulation of DM particles production by this package accommodates several possible scenarios, employing electron, muon or photon beams and involving various mediators, such as vector, axial vector, scalar, pseudoscalar, or spin 2 particles. The bremsstrahlung, annihilation or Primakoff processes can be simulated.
The package DMG4 contains a subpackage DarkMatter with cross section methods weakly connected to Geant4. It can be used in different frameworks.
In this paper, we present the latest developments of the package, such as extending the list of possible mediator particle types, refining formulas for the simulation and extending the mediator mass range. The user interface is also made more flexible and convenient.
In this work, we also demonstrate the usage of the package, the improvements in the simulation accuracy and some cross check validations.
Program title: DMG4
CPC Library link to program files:https://doi.org/10.17632/cmr4bcrj6j.1
Licensing provisions: GNU General Public License 3
Programming language: c++
Journal reference of previous version: Comput. Phys. Commun. 269 (2021) 108129
Does the new version supersede the previous version?: Yes
Reasons for the new version: Numerous developments, addition of new features
Summary of revisions: WW approximation cross sections for the muon beam are implemented and cross-checked, models with semivisible A′ (inelastic Dark Matter) and spin 2 mediators are added. The range of possible mediator masses is extended. Several important improvements for the annihilation processes are made, the number of possible annihilation processes is extended. User interface is improved. Several bugs are fixed.
Nature of problem: For the simulation of Dark Matter production processes in fixed target experiments a code that can be easily integrated in programs for the full simulation of experimental setup is needed.
Solution method: A fully Geant4 compatible DM simulation package DMG4 was presented in 2020. We present numerous further developments of this package.
Nineteen patients with congenital adrenal hyperplasia (CAH) aged over 16 years were given a neuropsychological evaluation; no significant differences with individually matched normal controls were ...detected. CAH subjects, however, revealed slightly higher IQs with respect to the expected distribution. No significant learning disabilities could be detected. Fifteen patients underwent nuclear magnetic resonance (NMR); 4 subjects showed small areas of increased signal intensity in the white matter, without prevalence of side; this finding did not correlate with clinical and cognitive characteristics. The results are discussed in the light of possible hormonal influences.
The search for new comparably light (well below the electroweak scale) feebly interacting particles is an exciting possibility to explain some mysterious phenomena in physics, among them the origin ...of Dark Matter. The sensitivity study through detailed simulation of projected experiments is a key point in estimating their potential for discovery. Several years ago we created the DMG4 package for the simulation of DM (Dark Matter) particles in fixed target experiments. The natural approach is to integrate this simulation into the same program that performs the full simulation of particles in the experiment setup. The Geant4 toolkit framework was chosen as the most popular and versatile solution nowadays. The simulation of DM particles production by this package accommodates several possible scenarios, employing electron, muon or photon beams and involving various mediators, such as vector, axial vector, scalar, pseudoscalar, or spin 2 particles. The bremsstrahlung, annihilation or Primakoff processes can be simulated. The package DMG4 contains a subpackage DarkMatter with cross section methods weakly connected to Geant4. It can be used in different frameworks. In this paper, we present the latest developments of the package, such as extending the list of possible mediator particle types, refining formulas for the simulation and extending the mediator mass range. The user interface is also made more flexible and convenient. In this work, we also demonstrate the usage of the package, the improvements in the simulation accuracy and some cross check validations.
We present the first results from a proof-of-concept search for dark sectors
via invisible decays of pseudoscalar $\eta$ and $\eta'$ mesons in the NA64h
experiment at the CERN SPS. Our novel ...technique uses the charge-exchange
reaction of 50 GeV $\pi^-$ on nuclei of an active target as the source of
neutral mesons. The $\eta, \eta' \to invisible$ events would exhibit themselves
via a striking signature - the complete disappearance of the incoming beam
energy in the detector. No evidence for such events has been found with
$2.9\times10^{9}$ pions on target accumulated during one day of data taking.
This allows us to set a stringent limit on the branching ratio ${\rm Br}(\eta'
\to invisible) < 2.1 \times 10^{-4}$ improving the current bound by a factor of
$\simeq3$. We also set a limit on ${\rm Br}(\eta \to invisible) < 1.1 \times
10^{-4}$ comparable with the existing one. These results demonstrate the great
potential of our approach and provide clear guidance on how to enhance and
extend the sensitivity for dark sector physics from future searches for
invisible neutral meson decays.
The inclusion of an additional $U(1)$ gauge $L_\mu-L_\tau$ symmetry would
release the tension between the measured and the predicted value of the
anomalous muon magnetic moment: this paradigm assumes ...the existence of a new,
light $Z^\prime$ vector boson, with dominant coupling to $\mu$ and $\tau$
leptons and interacting with electrons via a loop mechanism. The $L_\mu-L_\tau$
model can also explain the Dark Matter relic abundance, by assuming that the
$Z'$ boson acts as a "portal" to a new Dark Sector of particles in Nature, not
charged under known interactions. In this work we present the results of the
$Z'$ search performed by the NA64-$e$ experiment at CERN SPS, that collected
$\sim 9\times10^{11}$ 100 GeV electrons impinging on an active thick target.
Despite the suppressed $Z'$ production yield with an electron beam, NA64-$e$
provides the first accelerator-based results excluding the $g-2$ preferred band
of the $Z'$ parameter space in the 1 keV $ < m_{Z'} \lesssim 2$ MeV range, in
complementarity with the limits recently obtained by the NA64-$\mu$ experiment
with a muon beam.
We report on a search for a new $Z'$ ($L_\mu-L_\tau$) vector boson performed
at the NA64 experiment employing a high energy muon beam and a missing
energy-momentum technique. Muons from the M2 ...beamline at the CERN Super Proton
Synchrotron with a momentum of 160 GeV/c are directed to an active target. A
signal event is a single scattered muon with momentum $<$ 80 GeV/c in the final
state, accompanied by missing energy, i.e. no detectable activity in the
downstream calorimeters. For a total statistic of $(1.98\pm0.02)\times10^{10}$
muons on target, no event is observed in the expected signal region. This
allows us to set new limits on part of the remaining $(m_{Z'},\ g_{Z'})$
parameter space which could provide an explanation for the muon $(g-2)_\mu$
anomaly. Additionally, our study excludes part of the parameter space suggested
by the thermal Dark Matter relic abundance. Our results pave the way to explore
Dark Sectors and light Dark Matter with muon beams in a unique and
complementary way to other experiments.
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