Determination of fission barrier height of Fr 210 and Ra 210 via neutron measurement

Fission barrier heights of short-lived nuclei away from line of β stability are not known reliably. Low-energy fission of Fr210 and Ra210, produced by (d,p) and (d,n) transfer reaction on the re-accelerated unstable beam Fr209 was investigated at HIE-ISOLDE. Four Timepix3 pixel detectors were installed on the body of the ACTAR TPC demonstrator chamber. Polyethylene converters were used for the detection of fast neutrons. Since no significant background was observed, it was possible to measure the spatial distribution of emitted neutrons reflecting the fission excitation function. Subsequent simulations employing the results of the talys code and available data on fission fragment distributions allowed to estimate directly the value of the fission barrier height for the neutron-deficient nucleus Fr210. This first direct measurement confirmed the reduction of the fission barrier compared to available theoretical calculations by 15-30%

Scaling slowly rotating asteroids with stellar occultations

Context. As evidenced by recent survey results, the majority of asteroids are slow rotators (spin periods longer than 12 h), but lack spin and shape models because of selection bias. This bias is skewing our overall understanding of the spins, shapes, and sizes of asteroids, as well as of their other properties. Also, diameter determinations for large (>60 km) and medium-sized asteroids (between 30 and 60 km) often vary by over 30% for multiple reasons. Aims. Our long-term project is focused on a few tens of slow rotators with periods of up to 60 h. We aim to obtain their full light curves and reconstruct their spins and shapes. We also precisely scale the models, typically with an accuracy of a few percent. Methods. We used wide sets of dense light curves for spin and shape reconstructions via light-curve inversion. Precisely scaling them with thermal data was not possible here because of poor infrared datasets: large bodies tend to saturate in WISE mission detectors. Therefore, we recently also launched a special campaign among stellar occultation observers, both in order to scale these models and to verify the shape solutions, often allowing us to break the mirror pole ambiguity. Results. The presented scheme resulted in shape models for 16 slow rotators, most of them for the first time. Fitting them to chords from stellar occultation timings resolved previous inconsistencies in size determinations. For around half of the targets, this fitting also allowed us to identify a clearly preferred pole solution from the pair of two mirror pole solutions, thus removing the ambiguity inherent to light-curve inversion. We also address the influence of the uncertainty of the shape models on the derived diameters. Conclusions. Overall, our project has already provided reliable models for around 50 slow rotators. Such well-determined and scaled asteroid shapes will, for example, constitute a solid basis for precise density determinations when coupled with mass information. Spin and shape models in general continue to fill the gaps caused by various biases

The Remark about an Analogy between Magnetocaloric Behaviour of Type II Superconductors and Ferromagnetic Materials

The analogy between magnetocaloric behaviour of type II superconductors and anisotropic ferromagnetic materials is discussed. Special attention is devoted to the influence of anisotropy on the negative magnetocaloric effect near phase transitions

Herculid meteor shower in the night of 30/31 May 2022 and the meteoroid properties

Context. A τ Herculid meteor outburst or even storm was predicted to occur by several models around 5 UT on 31 May 2022 as a consequence of the break-up of comet 73P/Schwassmann-Wachmann 3 in 1995. The multi-instrument and multi-station experiment was carried out within the Czech Republic to cover possible earlier activity of the shower between 21 and 1 UT on 30/31 May. Aims. We report meteor shower activity that occurred before the main peak and provide a comparison with the dynamical simulations of the stream evolution. The physical properties of the meteoroids are also studied. Methods. Multi-station observations using video and photographic cameras were used to calculate the atmospheric trajectories and heliocentric orbits of the meteors. Their arrival times were used to determine the shower activity profile. The physical properties of the meteoroids were evaluated using various criteria based on meteor heights. The evolution of the spectra of three meteors were studied as well. Results. This annual but poor meteor shower was active for the whole night many hours before the predicted peak. A comparison with dynamical models shows that a mix of older material ejected after 1900 and fresh particles originating from the 1995 comet fragmentation event was observed. The radiant positions of both groups of meteors were identified and were found to agree well with the simulated radiants. Meteoroids with masses between 10 mg and 10 kg were recorded. The mass distribution index was slightly higher than 2. The study of the physical properties shows that the τ Herculid meteoroids belong to the most fragile particles observed ever, especially among higher masses of meteoroids. The exceptionally bright bolide observed during the dawn represents a challenge for the dynamical simulations as it is necessary to explain how a half-metre body was transferred to the vicinity of the Earth at the same time as millimetre-sized particles

Particle tracking and radiation field characterization with Timepix3 in ATLAS

Four hybrid pixel detectors of Timepix3 technology, installed in the ATLAS experiment, were continuously taking data from April 2018 until the end of the Run-2 data taking period (December 2019). These detectors are synchronized with each other and the LHC orbit clock. They are capable of resolving the bunch structure of the LHC beams due to their time resolution of ∼2ns. Thus, they allow the characterization of the radiation field inside and outside bunch-crossing periods. This is shown for Timepix3 detectors at the extended barrel (x=-3.58 m, y=0.97 m, z=2.83 m). We apply pattern recognition methods to decompose the radiation field and determine the directionality of the minimum ionizing particles (MIP) component of the radiation field

Low-latency NuMI trigger for the CHIPS-5 neutrino detector

The CHIPS R&D Project aims to develop affordable large-scale water Cherenkov neutrino detectors for underwater deployment. In 2019, a 5kt prototype detector CHIPS-5 was deployed in northern Minnesota to potentially study neutrinos generated by the NuMI beam. This paper presents the dedicated low-latency triggering system for CHIPS-5 that delivers notifications of neutrino spills from the Fermilab accelerator complex to the detector with sub-nanosecond precision. Building on existing NOνA infrastructure, the time distribution system achieves this using only open-source software and conventional computing and network elements. In a time-of-flight study, the system reliably provided advance notifications 610±330ms prior to neutrino spills at 96% efficiency. This permits advanced analysis in real-time as well as hardware-assisted triggering that saves data bandwidth and reduces DAQ computing load outside time windows of interest

A two-layer Timepix3 stack for improved charged particle tracking and radiation field decomposition

We characterize a novel instrument designed for radiation field decomposition and particletrajectory reconstruction for application in harsh radiation environments. The device consists oftwo Timepix3 assemblies with 500 µm thick silicon sensors in a face-to-face geometry. Thesedetectors are interleaved with a set of neutron converters: $^{6}$LiF for thermal neutrons,polyethylene (PE) for fast neutrons above 1 MeV, and PE with an additional aluminum recoil protonfilter for neutrons above ∼4 MeV. Application of the coincidence and anticoincidencetechnique together with pattern recognition allows improved separation of charged and neutralparticles, their discrimination against γ-rays and assessment of the overall directionalityof the fast neutron field. The instrument's charged particle tracking and separation capabilitieswere studied at the Danish Center for Particle Therapy (DCPT), the Proton Synchrotron, and SuperProton Synchrotron with protons (50–240 MeV), pions (1–10 GeV/c and 180 GeV/c). After developingtemporal and spatial coincidence assignment methodology, we determine the relative amount ofcoincident detections as a function of the impact angle, present the device's impact angleresolving power (both in coincidence and anticoicidence channels). The detector response toneutrons was studied at the Czech Metrology Institute (CMI), at n_ToF and the Los Alamos NeutronScience Center (LANSCE), covering the entire spectrum from thermal up to 600 MeV. The measuredtracks were assigned to their corresponding neutron energy by application of the time of flighttechnique. We present the achieved neutron detection efficiency as a function of neutron kineticenergy and demonstrate how the ratio of events found below the different converters can be used toassess the hardness of the neutron spectrum. As an application, we determine the neutron contentwithin a PMMA phantom just behind the Bragg-peak during clinical irradiation condition withprotons of 160 MeV

The Design and Construction of the Chips Water Cherenkov Neutrino Detector

International audienceCHIPS (CHerenkov detectors In mine PitS) was a prototype large-scale water Cherenkov detector located in northern Minnesota. The main aim of the R&D project was to demonstrate that construction costs of neutrino oscillation detectors could be reduced by at least an order of magnitude compared to other equivalent experiments. This article presents design features of the CHIPS detector along with details of the implementation and deployment of the prototype. While issues during and after the deployment of the detector prevented data taking, a number of key concepts and designs were successfully demonstrated

The Design and Construction of the Chips Water Cherenkov Neutrino Detector

International audienceCHIPS (CHerenkov detectors In mine PitS) was a prototype large-scale water Cherenkov detector located in northern Minnesota. The main aim of the R&D project was to demonstrate that construction costs of neutrino oscillation detectors could be reduced by at least an order of magnitude compared to other equivalent experiments. This article presents design features of the CHIPS detector along with details of the implementation and deployment of the prototype. While issues during and after the deployment of the detector prevented data taking, a number of key concepts and designs were successfully demonstrated