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We present a direct method to measure fission product yield distributions (FPY) and isomeric yield ratios (IYR) for spontaneous fission (SF) fragments. These physical properties are of utmost importance to the understanding of basic nuclear physics, the astrophysical rapid neutron capture process ('r process') of nucleosynthesis, neutron star composition, and nuclear reactor safety. With this method, fission fragments are produced by spontaneous fission from a source that is mounted in a cryogenic stopping cell (CSC), thermalized and stopped within it, and then extracted and transported to a multiple-reflection time-of-flight mass-spectrometer (MR-TOF-MS). We will implement the method at the FRS Ion Catcher (FRS-IC) at GSI (Germany), whose MR-TOF-MS relative mass accuracy (~ 10-7) and resolving power (~ 600,000 FWHM) are sufficient to separate all isobars and numerous isomers in the fission fragment realm. The system's essential element independence and its fast simultaneous mass measurement provide a new direct way to measure isotopic FPY distributions, which is complementary to existing methods. It will enable nuclide FPY measurements in the high fission peak, which is hardly accessible by current techniques. The extraction time of the CSC, tens of milliseconds, enables a direct measurement of independent fission yields, and a first study of the temporal dependence of FPY distributions in this duration range. The ability to resolve isomers will further enable direct extraction of numerous IYRs while performing the FPY measurements. The method has been recently demonstrated at the FRS-ICr for SF with a 37 kBq 252Cf fission source, where about 70 different fission fragments have been identified and counted. In the near future, it will be used for systematic studies of SF with a higher-activity 252Cf source and a 248Cm source. The method can be implemented also for neutron induced fission at appropriate facilities.

For the first time, a 1.5-mm thick windowless liquid lithium jet was bombarded with a 1-2 mA beam of ~1.9 MeV protons, just above the neutron production threshold in lithium (1.880 MeV), to produce an unprecedented rate of ~3-5 × 10 SP 10 sp n/sec, which irradiated a secondary target of interest (Figure 2, left). Simulated neutron energy spectrum from natGa, the main component (more than 80% of atoms) of the GaIn target, when irradiated by 40 MeV deuterons, normalized to a total yield of 2.7 × 1014 n/sec/mA. High-intensity neutron beams and large amounts of radioactive nuclei are powerful tools for exploring uncharted areas of basic and applied science. Right: Measured neutron energy spectra for 7Li(p,n)7Be from narrow and broad energy proton beams, compared to a Maxwellian distribution of kT = 28 keV. [Extracted from the article]

Excellent spectroscopy for higher energy gamma-rays is obtained with thick pixelated CdZnTe detectors, despite the large hole trapping inherent in the CdZnTe material. Our detector design was assisted by means of a theoretical Monte-Carlo code for optimizing the pixelated detector geometry for obtaining pad signals with minimum dependence on the depth of gamma interaction. We present spectra obtained for the 662-keV line of [sup.137]Cs taken with a 1 cm x 1 cm x 1 cm CdZnTe detector with the anode segmented to a 4 x 4 array of pad electrodes. For each gamma interaction, signals for all 16 pad of the electrodes and for the common cathode electrode were digitized to enable further correction for the depth of gamma interaction and for the reconstruction of Compton scatter interactions. For single pixel events, the summed pad spectrum yields an energy resolution of 1.0% FWHM. For the reconstruction of Compton events with signals in two pad electrodes, we obtain a summed peak with an energy resolution of 1.4% FWHM. Index Terms--CdZnTe detectors, gamma spectroscopy.

This review paper presents the current state of the art imaging systems using room-temperature CdTe and CdZnTe X-ray and gamma-ray detectors. Imaging systems composed of both single elements and monolithic segmented CdTe and CdZnTe arrays are used in medical diagnostics, astronomy, research and industry. This paper is divided into two sections: The first section describes different types and configurations of CdTe or CdZnTe detectors used in imaging systems, with the emphasis on single charge carrier collection detectors and front-end read-out electronics in the form of application specific integrated circuits associated with these detectors. It also discusses the advantages, disadvantages and limitations with respect to the efficiency and area of the imaging systems using CdTe and CdZnTe detectors compared to other types of X and gamma ray detectors. The second section describes several examples of imaging systems utilizing CdZnTe detectors: 1) a large area imaging telescope for the detection of gamma ray bursts using a coded aperture collimator; 2) a large area medical nuclear camera for cardiology and scintimammography using a parallel hole collimator; 3) a large field of view gamma camera based on a rotating slat collimator; and 4) a prototype of an electronically collimated Compton camera.

We present results for 1 cm x 1 cm x 1 cm pixelated CdZnTe gamma detectors with coarse segmentation. Large pixelated CdZnTe detectors are important for spectroscopic and imaging applications requiring sensitivity for higher gamma energies. For each gamma interaction, we process signals from all pixels and from the common electrode, and employ correction techniques developed at Soreq NRC for improving the energy resolution and the photopeak efficiency. For irradiation with an uncollimated [sup.133]]Ba source, we obtain a combined pad spectrum with energy resolution of ~5% full width half maximum (FWHM) for the 81-keV peak and ~1.5% FWHM for the 356-keV peak. We show spectra for two selected detectors, one with [([micro][tau]).sub.e] = 7.3 x [10.sup.-3] [cm.sup.2]/v, and one with [([micro][tau]).sub.e] = 2.9 x [10.sup.-3] [cm.sup.2]/v. We discuss the importance of detector material with high electron [([micro][tau]).sub.e] for thick pixelated detectors. The experimental results are compared to theoretical simulations. These simulations contribute to our understanding of large pixelated detectors and provide a tool for designing new pixelated detector configurations. Index Terms--CdZnTe, room temperature, solid-state gamma detectors.

Even after a century of research, major aspects of nuclear physics still remain unknown, especially away from the valley of stability, or that require precise measurement of ultra-rare phenomena. Exploring this terra-incognita may shed new light on the genesis of elements in the universe, and may provide an excellent probe to physics beyond the Standard Model of elementary particles. [ABSTRACT FROM PUBLISHER]

Edge effects in pixelated CdZnTe detectors occur due to the high dielectric constant of the CdZnTe detector material, and the tendency of the field lines emanating from the "hole" charge carriers to remain within the detector volume. As a result, spectra, for edge and corner pixels tend to exhibit a longer low energy tail at the expense of the number of events in the photo-peak. We focus on a thick pixelated CdZnTe detector, where, the detector thickness is comparable to the lateral size. We develop a theoretical Monte-Carlo simulation that well describes the experimentally observed edge effects. We show that when the same detector is embedded in an array of similar detector at the same HV, the edge effects disappear, and the spectral properties the edge and corner pixels improve markedly. [ABSTRACT FROM AUTHOR]

Excellent spectroscopy for higher energy gamma-rays is obtained with thick pixelated CdZnTe detectors, despite the large hole trapping inherent in the CdZnTe material. Our detector design was assisted by means of a theoretical Monte-Carlo code for optimizing the pixelated detector geometry for obtaining pad signals with minimum dependence on the depth of gamma interaction. We present spectra obtained for the 662-keV line of 137Cs taken with a 1 cm × 1 cm × 1 em CdZnTe detector with the anode segmented to a 4 × 4 array of pad electrodes. For each gamma interaction, signals for all 16 pad of the electrodes and for the common cathode electrode were digitized to enable further correction for the depth of gamma interaction and for the reconstruction of Compton scatter interactions. For single pixel events, the summed pad spectrum yields an energy resolution of 1.0% FWHM. For the reconstruction of Compton events with signals in two pad electrodes, we obtain a summed peak with an energy resolution of 1.4% FWHM. [ABSTRACT FROM AUTHOR]

Excellent spectroscopy for gamma rays can be obtained with pixelated CdZnTe detectors. Correction to the depth dependence of the pixel electrode signal can be made by simultaneously also measuring the common electrode signal. For high-energy gammas, thick detectors are required for increased detection efficiency. For increased efficiency, it is desirable to reconstruct Compton events, 2-pixel events that include the Compton scatter and re-interaction. The ambiguity in depth information for two pixel events in the same detector, with only one common signal, can be overcome taking advantage of sharp correlation with the relative difference of these two pixels. We present measurements made with a 1cm × 1cm × 1cm CdZnTe detector with the anode segmented to a 4 × 4 array of pad electrodes. For each gamma interaction, signals for all the 16 pad electrodes and for the common cathode electrode were digitized to enable further correction for the depth of gamma interaction, and for the reconstruction of Compton scatter interactions. We focus on the 1.115 MeV line of 65Zn source. For single pixel events, the summed corrected pad spectra yields an energy resolution of better than 1.0 % FWHM. Reconstruction of Compton events were made with signals from all combinations of 2 nearest neighbor pad electrodes, with corrections relying on the common electrode signal and also on the relative difference between the two pixel signals. A summed spectrum was for the Compton events was obtained with a energy resolution of 1.1 % FWHM for the 1.115 MeV line. [ABSTRACT FROM AUTHOR]

Due to technical constraints this article was published in volume 240:1 with erroneous article citation ID number 3 whereas this should have been 73 which is corrected as such. Springer Nature sincerely apologizes towards the author(s) for the inconvenience caused. [ABSTRACT FROM AUTHOR]

A novel method for simultaneous measurement of masses, Q-values, isomer excitation energies, half-lives and decay branching ratios of exotic nuclei has been demonstrated. The method includes first use of a stopping cell as an ion trap, combining storage of mother and daughter nuclides for variable durations in a cryogenic stopping cell (CSC), and afterwards the identification and counting of them by a multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS). We utilized our method to record the decay and growth of the 216Po and 212Pb isotopes (alpha decay) and of the 119m2Sb isomer ( t 1 / 2 = 850 ± 90 ms) and 119gSb isotope (isomer transition), obtaining half-lives consistent with literature values. The amount of non-nuclear-decay losses in the CSC up to ∼ 10 s is negligible, which exhibits its extraordinary cleanliness. For 119Sb isotopes, we present the first direct measurements of the mass of its ground state, and the excitation energy and decay branching ratios of its second isomeric state (119m2Sb). This resolves discrepancies in previous excitation energy data, and is the first direct evidence that the 119m2Sb isomer decays dominantly via γ emission. These results pave the way for the measurement of branching ratios of exotic nuclei. [ABSTRACT FROM AUTHOR]

The FRS Ion Catcher at GSI enables precision experiments with thermalized projectile and fission fragments. At the same time it serves as a test facility for the Low-Energy Branch of the Super-FRS at FAIR. The FRS Ion Catcher has been commissioned and its performance has been characterized in five experiments with 238U and 124Xe projectile and fission fragments produced at energies in the range from 300 to 1000 MeV/u. High and almost element-independent efficiencies for the thermalization of short-lived nuclides produced at relativistic energies have been obtained. High-accuracy mass measurements of more than 30 projectile and fission fragments have been performed with a multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS) at mass resolving powers of up to 410,000, with production cross sections down to the microbarn-level, and at rates down to a few ions per hour. The versatility of the MR-TOF-MS for isomer research has been demonstrated by the measurement of various isomers, determination of excitation energies and the production of a pure isomeric beam. Recently, several instrumental upgrades have been implemented at the FRS Ion Catcher. New experiments will be carried out during FAIR Phase-0 at GSI, including direct mass measurements of neutron-deficient nuclides below 100Sn and neutron-rich nuclides below 208Pb, measurement of β-delayed neutron emission probabilities and reaction studies with multi-nucleon transfer. [ABSTRACT FROM AUTHOR]