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The studies on the development of fusion–fission hybrid reactors (FFHR) have gained consensus in recent years as an intermediate step before fusion energy. This work proposes a possible approach to FFHRs based on the coupling of a Reversed Field Pinch fusion machine and a Molten Salt Subcritical fission test bed. The proposed test bed is characterized by the coexistence of a fast-neutron fission core and a dedicated thermal-neutron zone, allowing the performing of tritium breeding and actinides transmutation studies. The neutronic design solutions and the results obtained by the irradiation of FLiBe salt (inside the thermal-neutron zone) and of an actinide target (inside the core) are shown. The outcomes of the analysis reveal the potential of FFHR systems as breeding/burner systems. In particular, the results regarding tritium breeding are very encouraging as the system is demonstrated to be able to reach a very high Tritium Breeding Ratio. [ABSTRACT FROM AUTHOR]

The decommissioning of nuclear installations, as well as the possible necessary accident remediations, requires the physical presence of human operators in potentially radiologically hostile environments. The number of active nuclear reactors worldwide is greater than 400, and most of them are 40 to 50 years old, thus implying that soon they will have to be dismantled. In the framework of the H2020 CLEANDEM project, a small robotic vehicle is being developed that is equipped with a series of different sensors for areas that are significantly contaminated by radiation. In this work, we describe the MiniRadMeter system, a compact low-cost sensor capable of being used to perform quick gamma and neutron radiation field mapping of environments prior to the possible start of human operations. The miniature gamma sensor is a 1 cm3 scintillator counter with moderate spectroscopic features read out by means of a 6 × 6 mm2 SiPM, whereas neutrons are detected by means of a silicon diode coupled to a layer of 6LiF and placed inside a 6 × 6 × 6 cm3 polyethylene box. The front-end and data acquisition electronics were developed based on a Raspberry Pi4 microcomputer. In this paper, the system performance and the preliminary test results are described. [ABSTRACT FROM AUTHOR]

Precise knowledge of the energy and lifetime of 229mTh isomeric state has notable importance as a basis for a nuclear clock. Such a clock would be capable to extend precision on the oscillator frequency by up to four orders of magnitude compared to the presently best atomic clocks. However, the technique proposed for the clock requires that the isomeric state energy is accessible with existing laser systems. Previous measurement placed this state at ∼8 eV (150 nm), in the Vacuum Ultra Violet (VUV) range of the electromagnetic spectrum. A precise direct measurement of the energy of this state is necessary to determine whether the nuclear clock can be made using existing laser technology. We are developing a cryogenic microcalorimeter to measure the energy and lifetime of the 229mTh isomeric state directly. The experiment will use a 233U source whose alpha-decay will populate the 229mTh isomeric state with 2% probability. The subsequent decay of 229mTh will be measured by a Transition Edge Sensor (TES) with <1 eV resolution. Such a technique will allow to observe all possible types of decays of 229mTh in the range of energy from 3 to 50 eV and lifetimes >5 microseconds. The single-photon TES has sufficient resolving power combined with high efficiency in the whole energy band for this experiment. Here we present a prototype of TES based on a 200 nm thick iridium-gold (Ir/Au) film which was tested with a pulsed laser source and demonstrated ∼0.8 eV energy resolution and 5.8 ± 2.1 μs signal recovery time. [ABSTRACT FROM AUTHOR]

Diamonds are very promising candidates for the neutron diagnostics in harsh environments such as fusion reactors because of their proven radiation hardness. In comparison to the standard neutron diagnostics currently used (i.e., fission chambers, silicon based detectors, scintillators) CVD diamonds are less sensitive to $\gamma $ rays, which represents a huge background in fusion devices. Furthermore, their low leakage current provides a high energy resolution. A CVD diamond based detector has been proposed for the measurement of the 14 MeV neutrons from DT fusion reaction. The prototype was arranged in a proton recoil telescope configuration, featuring a plastic converter in front of the sensitive volume, in order to induce the (n, n) reactions which generate the recoil protons. The segmentation of the sensitive volume, achieved using two crystals with two dedicated electronic readouts, allowed to perform measurements in coincidence, which suppressed the neutron-carbon elastic scattering background. A preliminary prototype was assembled and tested at FNG (Frascati Neutron Generator), showing promising results regarding efficiency and energy resolution. [ABSTRACT FROM PUBLISHER]

The section offers news briefs related to nuclear physics in Europe. The European Collaboration on Stable ion beams (ECOS) town-meeting was held in Paris, France on October 5-6, 2006. The Italian Istituto Nazionale di Fisica Nucleare (INFN) and Ansaldo Nucleare agreed to collaborate on nuclear energy research for energy production. Enzo De Sanctis has been appointed as the new Editor-in- Chief of the "European Physical Journal A (EPJA)."

The cross section for the reaction ep → e'pπ+π- was measured in the resonance region for 1.4 < W < 2.1 GeV and 0.5 < Q² <1.5 GeV²/c² using the CIJAS detector at Jefferson Laboratory. The data show resonant. structures not. visible in previous experiments. The comparison of our data to a phenomenological prediction using available information on N* and Δ states shows an evident discrepancy. A better description of the data is obtained either by a sizeable change of the properties of the P13(1720) resonance or by introducing a new baryon state, not reported in published analyses. [ABSTRACT FROM AUTHOR]

We conducted measurements on the photo- and radio-luminescence of thin ThF 4 films in both the UV and visible ranges. In the UV range, we found that both luminescences are at a similar level as the internal dark counting noise of the photo-multiplier-tube (PMT). Our results suggest that thin ThF 4 crystals could be used as a target for the search for 229 m Th and as a medium for the future nuclear clock. The measurements indicate that using a small and thin ThF 4 film can reduce background noise while maintaining the signal at the same level, achieved by increasing the 229Th enrichment. Our developed apparatus is now ready for direct measurements of 229 m Th excitation and decay in ThF 4. [ABSTRACT FROM AUTHOR]

Large Area Picosecond PhotoDetectors (LAPPDs) are photosensors based on microchannel plate technology with about 400 cm 2 sensitive area. The external readout plane of a capacitively coupled LAPPD can be segmented into pads providing a spatial resolution down to 1 mm scale. The LAPPD signals have about 0.5 ns rise time followed by a slightly longer fall time and their amplitude reaches a few dozens of mV per single photoelectron. In this article, we report on the measurement of the time resolution of an LAPPD prototype in a test beam exercise at CERN PS. Most of the previous measurements of LAPPD time resolution had been performed with laser sources. In this article we report time resolution measurements obtained through the detection of Cherenkov radiation emitted by high energy hadrons. Our approach has been demonstrated capable of measuring time resolutions as fine as 25-30 ps. The available prototype had performance limitations, which prevented us from applying the optimal high voltage setting. The measured time resolution for single photoelectrons is about 80 ps r.m.s. [ABSTRACT FROM AUTHOR]