Fission studies in inverse kinematics and associated development of new time-of-flight

This work focuses on the proton- and deuteron-induced fission of 181Ta and 208Pb measured in experiments performed at GSI (Helmholtzzentrum für Schwerionenforschung - Darmstadt Alemania) using the inverse kinematics technique. According to this scope, a dedicated experimental setup with high acceptance and efficiency for fission measurements is used. The obtained results allow to improve the knowledge about fission cross sections of relevance for the construction of spallation neutron sources useful in many technology areas. In addition, reaction codes based on models describing the fission process at high excitation energies are also investigated and benchmarked by comparison to our experimental data. The experimental part is completed with the R and D of Resistive Plate Chambers (RPC) for the construction of a time-of-flight detector for the R3B experiment in the forthcoming FAIR facility (Darmstadt)

The Urban Deployment Model: A Toolset for the Simulation and Performance Characterization of Radiation Detector Deployments in Urban Environments

Static and mobile radiation detectors can be deployed in urban environments for a range of nuclear security applications, including radiological source search-and-tracking scenarios. Modeling detector performance for such applications is challenging, as it does not depend solely on the detector capabilities themselves. Many factors must be taken into consideration, including specific source and background signatures, the topology and constraints of the deployment environment, the presence of nuisance sources, and whether detectors are mobile or static. When considering the simultaneous deployment of multiple, heterogeneous detectors, assessment of the system-wide performance requires the simulation of the individual detectors, and a system-level analysis of the detection performance. In radiological source search-and-tracking scenarios, performance is mostly dominated by the probability of encounter, which depends on the specifics of a given deployment, e.g., static vs. mobile detectors or a combination of both modalities, the number of detectors deployed, the dynamic vs. static setting of false alarm rates, and individual vs. networked operation. The Urban Deployment Model (UDM) toolset was specifically developed to cover the gap in the available generic frameworks for the simulation of radiation detector deployments at city scales. UDM provides a unified and modular framework to support the simulation and performance characterization of heterogeneous detector deployments in urban environments. This paper presents the key components along the UDM workflow

Neutron skin and signature of the N = 14 shell gap found from measured proton radii of 17−22N

A thick neutron skin emerges from the first determination of root mean square radii of the proton distributions for 17−22N from charge changing cross section measurements around 900A MeV at GSI. Neutron halo effects are signalled for 22N from an increase in the proton and matter radii. The radii suggest an unconventional shell gap at N = 14 arising from the attractive proton–neutron tensor interaction, in good agreement with shell model calculations. Ab initio, in-medium similarity re-normalization group, calculations with a state-of-the-art chiral nucleon–nucleon and three-nucleon interaction reproduce well the data approaching the neutron drip-line isotopes but are challenged in explaining the complete isotopic trend of the radii.The authors are thankful for the support of the GSI accelerator staff and the FRS technical staff for an efficient running of the experiment. The support from NSERC, Canada for this work is gratefully acknowledged. The support of the PR China government and Beihang University under the Thousand Talent program is gratefully acknowledged. The experiment work is partly supported by the grant-in-aid program of the Japanese government under the contract number 23224008. This work is partly supported by Grants-in-Aid for Scientific Research (JP15K05090) of the JSPS of Japan. It is supported by the Office of Nuclear Physics, U.S. Department of Energy (Oak Ridge National Laboratory), DE-SC0008499 (NUCLEI SciDAC collaboration), NERRSC Grant No. 491045-2011, and the Field Work Proposal ERKBP57 at Oak Ridge National Laboratory. Computer time was provided by the Innovative and Novel Computational Impact on Theory and Experiment (INCITE) program. TRIUMF receives funding via a contribution through the National Research Council Canada. This research used resources of the Oak Ridge Leadership Computing Facility located in the Oak Ridge National Laboratory, which is supported by the Office of Science of the Department of Energy under Contract No. DE-AC05-00OR22725, and used computational resources of the National Center for Computational Sciences and the National Institute for Computational Sciences. The authors thank B. Davids for a careful reading of the manuscript.S

Kinematics reconstruction in solenoidal spectrometers operated in active target mode

We discuss the reconstruction of low-energy nuclear reaction kinematics from charged-particle tracks in solenoidal spectrometers working in Active Target Time Projection Chamber mode. In this operation mode, reaction products are tracked within the active gas medium of the Active Target with a three dimensional space point cloud. We have inferred the reaction kinematics from the point cloud using an algorithm based on a linear quadratic estimator (Kalman filter). The performance of this algorithm has been evaluated using experimental data from nuclear reactions measured with the Active Target Time Projection Chamber (AT-TPC) detector

Active target MAIKo to investigate cluster structures in unstable nuclei

Study on clustering of nucleons in nuclei is recently focusing on unstable nuclei where new kinds of structures, namely molecular structures with excess nucleons, are predicted. The Coulomb shift of energy in the mirror system is suggested to reflect the size of these structures. Although the missing mass spectroscopy is expected to give access to these structures even beyond particle decay thresholds without any biases in excitation energy spectra but the detection of very low energy particles is challenging. To satisfy the requirement, a new active target system MAIKo has been developed at RCNP. The detector was commissioned using a 13C beam under the same kinematical condition as that of RI beam experiments