Several instances of anomalously low values of the B(E2;41+→21+)B(E2;21+→0gs+) ratio (B4/2)<1 have previously been observed in several nuclei among the highly neutron deficient W-Os-Pt isotopes with even numbers of neutrons and protons. The relatively large number of cases suggests a striking new phenomenon that currently has no theoretical explanation. A clue to its origin might be achieved by comparing the B4/2 ratios in even-even nuclei with the corresponding ratios of transition rates in neighboring odd-mass nuclei. However, until now only one case (Os169) has been observed with an unusually low corresponding B4/2 ratio, approximately 1σ below 1. Electromagnetic transition rates between excited states in the extremely neutron deficient nuclide Os167 were measured using 15 single-crystal germanium detectors from the jurogam 3 array coupled to the RITU gas-filled separator. The excited states of interest were populated via the Mo92(Kr78,2pn) fusion-evaporation reaction and studied by selecting the rare reaction channel via recoil-α-decay tagging. The lifetimes of low-lying states were measured using the recoil distance Doppler shift method with the APPA plunger device. From the measured lifetimes in the rotational-like band structure assigned to the νi13/2 yrast intruder configuration, the B(E2;17/2+→13/2+) and B(E2;21/2+→17/2+) values were deduced, resulting in the ratio B(E2;21/2+→17/2+)B(E2;17/2+→13/2+)=0.49(10). The results were compared with previous measurements in the Os isotopic chain and theoretical mean-field calculations, implying that the odd neutron valence particle has limited, if any, influence on the B4/2 values for this particular single-particle configuration.

Earthquakes, as one of the most prominent natural disasters, pose a severe threat to societies in regions near active fault lines. Being able to forecast when, where and how strong an earthquake will be is beyond current scientific capabilities. At present, forecasting methods yield earthquake occurrence probabilities within a specific time frame spanning several years. Measurements of changes of radon concentrations in groundwater have shown pronounced changes preceding imminent earthquakes. The potential in using radon as a precursor for earthquakes has been explored by multiple groups over many years. Radon measurements in soil have shown large variations in activity, partly due to atmospheric influences. The ArtEmis project seeks to offer new insight into the correlation between imminent earthquakes and changes in radon emission from the upper crust by employing novel concepts for measurements and analysis. The paper presents system aspects of the ArtEmis project, a description of the ArtEmis sensor prototype and first results.

In late February 2024, a swarm–like seismic activity took place north of Kefalonia Island, in the area of central Ionian Islands. Following a machine-learning aided workflow, we compiled an enhanced, relocated seismic catalog of 2495 low- to moderate magnitude earthquakes during a 2–month period. Spatiotemporal analysis reveals a narrow epicentral distribution of nearly E-W alignment, approximately 5 km long, much longer than the length anticipated by common scaling laws for the aftershock area extension of the stronger earthquakes that did not exceed M4. Seismic activity decays at a rate slower than mainshock-aftershock sequences, providing evidence of swarm-like behavior. Fluid diffusion appears to be the critical driving force behind this sequence, effectively reproducing the spatiotemporal diffusion of the analyzed activity, whereas cascade triggering due to stress changes and transfer by the combined effect of the two relatively strongest earthquakes promote the triggering of most of the weaker earthquakes that follow in the sequence. Our ML-enhanced spatiotemporal analysis, along with the computation of 17 focal mechanisms of the stronger earthquakes using waveform modeling, support the presence of a population of smaller faults that strike obliquely in respect to the Kefalonia Transform Fault Zone (KTFZ) forming a strike slip duplex in the area between them.

With the recent lifetime measurements of the 2 + states in Te 116 and Te 118 , the evolution of the collectivity in the midshell region of the Te isotopic chain is starting to reveal itself. However, more information on the structure of the ground-state bands and the nature of the collectivity can be gathered from studying the odd-mass systems, in which lifetimes have not been extensively studied.

The purpose of the present work is to investigate the structure of low-lying excited states of the ν h 11 / 2 band in the odd-mass systems Te 117 and Te 119 , that correspond to the ground-state band in even-even Te.

Lifetimes of low-lying states in the ν h 11 / 2 band of Te 117 are measured for the first time and remeasured in Te 119 , using the recoil distance Doppler shift technique, and analyzed with the differential decay curve method in coincidence mode.

The lifetimes and B (E2) values of the first two transitions, 15 / 2 − → 11 / 2 − and 19 / 2 − → 15 / 2 − , in the ν h 11 / 2 band, are determined in both Te 117 and Te 119 . From the lifetimes, the B (E2) values and corresponding B 4 / 2 ratios are determined. The results are compared to systematics in both even- A and odd- A Te isotopes, as well as with theoretical results from the large-scale shell model and interacting boson model calculations.

While the energy levels of Te 117 and Te 119 , similarly to Te 118 , exhibit textbook vibrational behavior, the unexpectedly small B 4 / 2 ratios of these odd-mass nuclei point to a puzzling discrepancy and question the vibrational nature of these states.

In recent years, several cases of nuclei presenting the so-called "B-4/2 anomaly" have been observed in the neutron-deficient region close to Z = 50 and Z = 82. In the last region, the osmium isotopic chain is of particular interest, as three consecutive isotopes, 168,169,170Os, have shown the presence of this peculiar phenomenon. An experiment aimed at extending the study to Os-167 was performed at the Accelerator Laboratory of the University of Jyvaskyla, using a beam of 78Kr at 360 MeV impinging on a Mo-92 target. Lifetimes of several low-lying states were measured using the Recoil-Distance Doppler Shift method. The preliminary analysis and the study of the influence of unobserved feeders are discussed.

In the last two decades, several unique phenomena in triaxially deformed nuclei, such as chiral doublet bands and wobbling motion have been revealed. Up to now, there are still many open questions which require further experimental and theoretical studies. To explore the collective motion in 131Ba, an experiment was performed using the XTU Tandem accelerator in the Legnaro laboratory, Italy. High-spin states of 131Ba have been populated via the heavy-ion fusion-evaporation 122Sn(13C, 4n) reaction. g-rays, charged particles and neutrons emitted from the residues were detected by the GALILEO array, EUCLIDES silicon ball, and the Neutron Wall, respectively. A total of 1.2 ×109 triple- or higher-fold events were collected by the GALILEO data acquisition system. The g-g-g coincidence events were sorted into a three-dimensional histogram (cube) and the analysis was carried out with the RADWARE and GASPWARE software packages. Through analysis of the coincidences between g-rays, the most comprehensive level schemes of 131Ba to date was deduced from the present work. The extended level-scheme consists of 15 rotational bands, and newly observed transitions are marked in red. Three nearly degenerate pairs of doublet bands (Band 3–8) are identified in 131Ba. Two pairs of chiral doublets (Band 3–6) with configuration πh11/2(g7/2,d5/2)×νh11/2 are interpreted as a set of pseudospin-chiral quartet bands. The quartet bands are fed by another pair of chiral doublet bands (Band 7–8) built on a πh211/2×νh11/2 configuration via a series of enhanced E1 transitions. We extracted the energy displacement δE and the B(E1)/B(E2) branching ratios between the positive-parity band 3 and the negative-parity band 7 in 131Ba and in comparison with those in 124Ba, 224Th, 133Ce and 135Nd. The energy displacement δE and the B(E1)/B(E2) branching ratios in 131Ba are comparable with those in 124Ba but deviate appreciably from those in 224Th which has been reported to have stable octupole deformation. The results indicate the existence of octupole correlations in 131Ba without stable octupole deformation. A new rotational band (Band 10) discovered in the low-spin region exhibits a level structure similar to a wobbling band. Assuming it as a wobbling band, the wobbling frequency was extracted and compared with other reported wobbling bands in the neighboring nuclei. The wobbling frequency of this band decreases with increasing angular momentum, and even exhibits negative value at the highest spin. Considering that the wobbling phonon should contribute a positive amount to the excitation energy, this band is unlikely to be explained by this mechanism. The band may originate from other collective excitation mechanisms such as g vibration. The newly identified rotational band (Band 9) composed of M1 transitions is tentatively assigned as a magnetic rotational band through a systematic analysis of the level structure. Finally, the configurations of other 4 bands, Band 12-15, are also suggested based on previous researches and the extracted quasiparticle alignments.

Dose -mean lineal energies were measured using the variance-covariance method and commercial ionisation chambers in a therapy level 60 Co field at several different air pressures. The results confirmed the trend from previous studies and the experimental data was extended down to a simulated object diameter of 4.2 nm using a low -noise electrometer. The variance-covariance method was adapted to consecutive charge integrations from a single ionisation chamber and used to correct for signal variations due to pressure drifts in the ion chamber. Monte Carlo simulations using MCNP 6.2 were performed, and the results follow the trend of the experimental values in the nanometric region.

The manuscript provides a comprehensive review of the results that have been obtained from radon concentrations in the ground, particularly their correlation with earthquakes, over the past fifty years in Greece. Data collection methods have evolved from solid-state nuclear track detectors to more advanced continuous monitoring devices. The influence of meteorological parameters was eliminated through time series analysis, revealing correlations between radon signals and earthquakes M3.5–6.5. Anomalies persisted for days to weeks, depending on the faulting type. The review concludes with a discussion and evaluation of the results, highlighting the potential for future research on this intriguing correlation between radon and earthquakes.

Since the advent of the new generation of germanium detector arrays for low-energy nuclear physics experiments utilizing gamma-ray tracking, the challenges associated with track-reconstruction methods have been extensively studied. In the present work an approach based on recent developments in machine learning was used to address the problem. Here, a graph neural network was constructed and trained on data simulated in Geant4 in order to attempt track reconstruction of gamma rays below 1 MeV in a spherical shell geometry of pure germanium. Using a thick-shell geometry, and simulated data without energy-and position uncertainties the network achieved a reconstruction rate above 80% for complete tracks, and a combined peak-to-total value of 85% for energy spectra with four discrete peaks. For data with added noise, i.e. finite resolution in interaction-point position and energy, the corresponding peak-to-total ratio dropped to 74%. The track reconstruction was stable across multiplicities 1-10 but showed an increased error frequency in the energy range between 50 keV and 250 keV. To specifically study the complication of gamma tracks lost by out -scattering from the detector volume, a thin-shell (9 cm thickness) geometry was used together with a modified version of the GNN framework. By letting the GNN code identify and discriminate the out-scatter events, an improvement of the P/T value from 66% to 75% was found for the packed, noisy data. For the sake of comparison the new GNN model with existing gamma-ray tracking methods, a separate instance of the network was trained on slightly higher energies (up to 1.5 MeV) and multiplicities (up to 15) to evaluate 1.332 MeV photon cascade data in terms of P/T and photo-peak efficiency. The results for this GNN data set, with P/T values at 85% for single tracks and 74% for multiplicity 15, show clear promise when compared to the existing tracking methods.

The electromagnetic transition probabilities of the yrast 2 + states in the midshell Te isotopes, two protons above the closed shell at Sn, are of great importance for the understanding of nuclear collectivity in these isotopes and the role played by the neutron-proton interactions and cross-shell excitations. However, the large uncertainty of the experimental data for the midshell nucleus 118Te and the missing data for 116Te make it difficult to pin down the general trend of the evolution of transition probabilities as a function of the neutron number. In this work, the lifetime of the yrast 2 + state in 118Te was measured, with the aim of reducing the uncertainty of the previous measurement. The result is τ2 += 7.46 (19) ps. In addition, the lifetime of the 4 + state was measured to be τ4 += 4.25 (23) ps. The experimental transition rates are extracted from the measured lifetimes and compared with systematic large-scale shell-model calculations. The trend of the B(E2 ; 0 +→ 2 +) values in the midshell area is in good agreement with the calculations and the calculated B4 / 2 ratio provide evidence for 118Te as a near perfect harmonic vibrator.