Dark Matter Interpretation of Neutron Multiplicity Anomalies

Subterrestrial neutron spectra show weak but consistent anomalies at multiplicities ~100 and above [1-3]. The data of the available measurements are of low statistical significance [4] but indicate an excess of events not correlated with the muon flux. The origin of the anomalies remains ambiguous but could be a signature of WIMP annihilation-like interaction with a Pb target. In this paper, we outline a model consistent with this hypothesis, the extended Standard Model (SM) approach called the Radiation Gauge Model (RGM) [5]. The RGM identifies scalar neutrino-antineutrino wave function components of WIMP Dark Matter (DM) responsible for the weak interaction leading to annihilation with ordinary matter. The model assigns neutrino-nucleon(target) charged current (CC) transitions to the observed anomalies. If the existence of the anomalies is confirmed and the model interpretation is positively verified, this will be the first terrestrial indirect detection of DM.Comment: TAUP 2023 proceeding

Centrality evolution of the charged-particle pseudorapidity density over a broad pseudorapidity range in Pb-Pb collisions at root s(NN)=2.76TeV

Peer reviewe

Patients to Peers: Barriers and Opportunities for Doctors with Disabilities

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.Comment: 4 pages, 1 figure, NIC-XI

Muon multiplicities measured using an underground cosmic-ray array

EMMA (Experiment with Multi-Muon Array) is an underground detector array designed for cosmic-ray composition studies around the knee energy (or ∼ 1 − 10 PeV). It operates at the shallow depth in the Pyh¨asalmi mine, Finland. The array consists of eleven independent detector stations ∼ 15 m2 each. Currently seven stations are connected to the DAQ and the rest will be connected within the next few months. EMMA will determine the multiplicity, the lateral density distribution and the arrival direction of high-energy muons event by event. The preliminary estimates concerning its performance together with an example of measured muon multiplicities are presented.peerReviewe

Halo-like structure in 7He nucleus

A study of the neutron structure of the ground state of 7He has been performed by means of registration and analysis of the decay channels of the residual nuclei following absorption of stopped pions. In particular, the reaction 9Be (${\pi }_{}^{-},d$)X have been investigated where X denotes any system with five neutrons and two protons – the constituencies of a 7He nucleus. It was shown that the structure of 7He is determined by correlations of two neutrons in the states 6He (0+), 6He (2+) and one neutron in the shell p3/2. The 4He+3n structure is not manifested in the ground state of 7He. The obtained results are consistent with the known data on considerable mixture of configurations "6He in its ground and first excited states plus a neutron" in the ground state of 7He. Comparison of the diffraction components of the differential cross-sections of the charge-exchange reactions (t, 3He) measured on 6Li and 7Li allowed extracting the radius of particle-unstable nucleus 7He. The latter occurred to be approximately equal to those of 6He and 8He. The obtained result indicates to existence of the halo-like structure in 7He.peerReviewe

High-multiplicity muon events observed with EMMA array

Abstract High-multiplicity data, collected with a segmented scintillator array of the cosmic-ray experiment EMMA (Experiment with Multi-Muon Array), is presented for the first time. The measurements were done at the depth of 75 meters (210 m.w.e.) in the Pyhäsalmi mine in Finland. EMMA uses two types of detectors: drift chambers and plastic scintillation detectors. The presented data were acquired over the period between December, 2015 and April, 2018 using 128-800 plastic scintillator pixels probing the fiducial area of ˜100 m². The results are being interpreted in terms of CORSIKA simulations. Several events with densities in excess of 10 muons per m² were observed. At the next stage of the analysis, the high-multiplicity events will be matched with precision tracking data extracted from the multi-layer drift chambers of EMMA. Observation of high-density muon bundles was first reported by the LEP experiments: DELPHI, L3+C, and ALEPH. More recently, the ALICE experiment at CERN has provided new cosmic-ray results together with improved interpretation benefiting from the updated cross section values extracted from LHC results. While the tracking performance of ALICE is superior to EMMA, the duration of ALICE cosmic-ray measurements is very limited. Over the period of 2010–2018 the total exposure was only 93 days while EMMA, having a similar overburden provides a larger footprint and collects data continuously

Underground cosmic-ray experiment EMMA

EMMA (Experiment with MultiMuon Array) is a new approach to study the composition of cosmic rays at the knee region (1 − 10 PeV). The array will measure the multiplicity and lateral distribution of the high-energy muon component of an air shower and its arrival direction on an event-by-event basis. The array operates in the Pyh¨asalmi Mine, Finland, at a depth of 75 metres (or 210 m.w.e) corresponding to the cut-off energy of approximately 50 GeV for vertical muons. The data recording with a partial array has started and preliminary results of the first test runs are presented.nonPeerReviewe

EAS selection in the EMMA underground array

The first measurements of the Experiment with MultiMuon Array (EMMA) have been analyzed for the selection of the Extensive Air Showers (EAS). Test data were recorded with an underground muon tracking station and a satellite station separated laterally by 10 metres. Events with tracks distributed over all of the tracking detector area and even extending over to the satellite station are identified as EAS. The recorded multiplicity spectrum of the events is in general agreement with CORSIKA EAS simulation and demonstrates the array’s capability of EAS detection.peerReviewe

Transfer cross sections at near-barrier energy for the 24Mg + 90,92Zr systems

We have tested the hypothesis that for systems 24Mg + 90,92Zr, the shape of the barrier height distribution is not influenced by transfers processes. The experiment was performed using the ICARE detector system at the Warsaw Cyclotron. Having measured the transfer cross sections of the near-barrier collisions of 24Mg + 90,92Zr, we have found them to be roughly half of the value obtained for the 20Ne + 90,92Zr systems. From that observation, we conclude that in the 24Mg + 90,92Zr case, the leading cause of washing out the barrier distribution structure is the partial dissipation of relative kinetic energy into the non-collective excitation of the system.peerReviewe