A significant fraction of stars between 7 and 11 solar masses are thought to become supernovae, but the explosion mechanism is unclear. The answer depends critically on the rate of electron capture ...on Ne20 in the degenerate oxygen-neon stellar core. However, because of the unknown strength of the transition between the ground states of Ne20 and F20, it has not previously been possible to fully constrain the rate. By measuring the transition, we establish that its strength is exceptionally large and that it enhances the capture rate by several orders of magnitude. This has a decisive impact on the evolution of the core, increasing the likelihood that the star is (partially) disrupted by a thermonuclear explosion rather than collapsing to form a neutron star. Importantly, our measurement resolves the last remaining nuclear physics uncertainty in the final evolution of degenerate oxygen-neon stellar cores, allowing future studies to address the critical role of convection, which at present is poorly understood
Yields of fission products are essential for designing Radioactive Ion Beam facilities and extracting cross section data to refine reaction models. This work reports the results of irradiations of ...natural uranium targets with a continuous spectrum of fast neutrons. A rapid transport system has been used to bring the targets in front of two segmented Clover detectors operated in coincidence. Decay
γ
-ray spectroscopy of the fission products has allowed for cross sections to be obtained in 61 mass chains, either as independent or as cumulative for the chain. Interpolation versus mass number together with the assumption of a Gaussian distribution of isobars enable cross sections to be evaluated in nearly 80 mass chains. The measurement demonstrates the power of the detectors for twofold
γ
–
γ
events following
β
-decay and indicates that new fission product decay data could be obtained with a dedicated set up.
Forward Diffractive Detector control system for Run 3 in the ALICE experiment Mejía Camacho, J.M.; Rodríguez Ramírez, S.A.; Cabanillas Noris, J.C. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2023, Letnik:
1050
Journal Article
Recenzirano
The ALICE experiment went through major upgrades in preparation for Runs 3 and 4 at the CERN LHC, which foresee a significant increase in the data stream rate. To cope with it, a new Computing System ...Online–Offline (O2) was developed by ALICE and several detectors were upgraded. One of these upgrades corresponded to the ALICE Diffractive (AD) detector, which was replaced by the new Forward Diffractive Detector (FDD). A fundamental system that allows for recording of data as well as for the stable and safe operation of the experimental setup is the Detector Control System (DCS). The DCS controls, monitors, and configures detectors’ hardware and their subsystems among which are commercial hardware and specific custom equipment. In this work, we describe the implementation of the DCS of FDD, which was designed and developed using the SCADA commercial software WinCC Open Architecture (WinCC-OA®) and the Joint Controls Project (JCOP) Framework. We also describe the modeling of FDD-DCS as a finite state machine to be integrated into the ALICE Central DCS, and to be operated by DCS shifters in the run control center and, remotely, by detector experts. This new DCS was developed to comply with the new LHC operational standards that allow for processing the increased luminosity due to collisions at a higher energy, and for fulfilling the specific requirements of the ALICE experiment, in order to address the scientific challenges of its physics program.
The Fast Interaction Trigger (FIT) detector will be essential for the operation of the ALICE experiment at CERN during Run 3 and 4 of the LHC . FIT will serve as an interaction trigger, luminometer, ...the first indicator of the vertex position, and the forward multiplicity counter. It will also provide the precise collision time for the TOF-based particle identification, yield the centrality and interaction plane for flow measurements, and measure cross sections of diffractive processes. In order to cope with an increased interaction rate of up to 1 MHz in proton-proton (pp) collisions and up to 50 kHz in Pb-Pb collisions, a new readout system for the ALICE FIT detector has been designed and implemented. FIT readout system is compatible both with the triggered and continuous (triggers-less) ALICE readout modes. The GBT-FPGA based FIT readout and trigger systems allow to stream data up to 5.5 MHz event rate with 3.2 Gbps data rate. The trigger processing time is only 225 ns. With the additional 200 ns delay along the connecting signal cables, the total latency of the FIT trigger is 425 ns.
Unsegmented, large-volume liquid scintillator (LS) neutrino detectors have proven to be a key technology for low-energy neutrino physics. The efficient rejection of radionuclide background induced by ...cosmic muon interactions is of paramount importance for their success in high-precision MeV neutrino measurements. We present a novel technique to reconstruct GeV particle tracks in LS, whose main property, the resolution of topological features and changes in the differential energy loss dE/dx, allows for improved rejection strategies. Different to common track reconstruction approaches, our method does not rely on concrete track / topology hypotheses. Instead, based on a reference point in space and time, the observed distribution of photon arrival times at the photosensors and the detector's characteristics in terms of photon production, propagation and detection (optical model), it reconstructs the voxelized distribution of optical photon emissions. Techniques from three-dimensional data analysis can then be applied to extract parameters describing the topology, e.g., the direction of a track. We performed a first performance evaluation of our method using single muon events with up to 10 GeV from a Geant4 simulation of the LENA detector. The current results indicate that our approach is competitive with existing reconstruction methods— although its full potential has not yet been exploited. We also remark on other detector technologies in astroparticle physics as well as applications in medical imaging that could benefit from the fundamental ideas of our method.
Abstract
A systematic investigation of Planacon MCP-PMTs was performed using 64 XP85002/ FIT-Q photosensors. These devices are equipped with microchannel plates of reduced resistance. Results of a ...study of their gain stability over time and saturation level in terms of the average anode current are presented. This information allows one to determine the lower limit of the MCP resistance for stable Planacon operation. The spread of the electron multiplication characteristics for the entire production batch is also presented, indicating the remarkably low voltage requirements of these MCP-PMTs. Detection efficiency and noise characteristics, such as dark count rate and afterpulsing level, are also reviewed.
The main findings of the LAGUNA Design Study are briefly discussed. Construction of giant underground detectors is technically feasible at several sites. Physics factors will dominate in the site ...selection.
.
In the context of the SPIRAL2 radioactive beam facility the production rate of the neutron-rich
15
C nucleus by
18
O(n,
α
) has been investigated. In a water target of 20 cm
3
, enriched in
18
O ...and placed behind the neutron converter, a rate of a few 10
10
nuclei per second can be reached with 1mA of 40MeV deuterons. A
18
O(n,
α
) cross-section based on the activation method is proposed. It is intermediate between the highest and lowest evaluations available to date.
We have measured and compared the characteristics of ALD-coated Planacon® MCP-PMTs (XP85112/A1-Q-L) with their non-ALD counterparts (XP85012/A1-Q). While the latter show excellent performance, the ...ALD-coated sensors have surprisingly low current saturation levels (∼ two orders of magnitude lower than expected) and extremely high gain recovery time (more than 7 orders of magnitude higher than expected). We suspect that these problems might be caused by the unexpected side-effects of the ALD process. To make a definite conclusion, more samples need to be tested, preferably from different production runs. If our observation were confirmed, it would mean a serious technological setback for ALD-coated MCP-PMTs.
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