[en] Data acquisition systems for nuclear spectroscopy have traditionally been based on hybrid systems with analog shaping amplifiers followed by analog-to-digital converters. Recently, however, new systems based on digital signal processing concepts have been developed. For example, one specific design, the Digital Gamma Finder (DGF-4C), has been used extensively for particle- and gamma-spectroscopy of nuclei far from stability. Using the DGF-4C, a variety of data acquisition systems have been implemented and used for measurements with semiconductor and scintillator detectors at recoil separators like the RMS at ORNL, the FRS at GSI and LISE at GANIL. Some novel features and unique advantages, such as trigger-less operation and pulse shape recording, are discussed in the context of selected studies

[en] β-delayed neutron emission is dominant for most neutron-rich nuclei and all isotopes on the r-process nucleosynthesis path, regardless of the astrophysical scenario. This two-step process combines beta decay and neutron emission; most models treat these two steps using independent models. With the new-generation facilities, access to very exotic isotopes was gained, which enabled a new perspective on understanding the fundamentals of this process. I will discuss the results of our decay spectroscopy measurements in ⁷⁸Ni and ¹³²Ni regions using various neutron arrays and how these results affected our modeling of beta-delayed neutron emission. (author)

[en] Significant progress have been made over the last decade in experimental investigation of the ⁷⁸Ni and its neighbors. Nuclear Decay studies acieved life-time measurement of the doublt-ymagic ⁷⁸Ni and provided excitation enrgies of low lying levels up to ⁷⁶Ni, establishing the 'baseline' systematics of the nuclear structure knowledge for this region of nuclear chart. Perspective studies which will build on this research are presented. One major goal is determine, if ⁷⁸Ni is a good double closed-shell nucleus. The answer to this question may have profound consequences for astrophysics and also our understanding of the nuclear models describing properties of very neutron rich nuclei.

[en] Recent progress in experimental decay studies in the region of the doubly magic nucleus ⁷⁸Ni is discussed. In particular new data on low-energy excitations in nickel isotopes has been obtained in experiments employing fragmentation reactions. The experimental data are confronted with different shell-model calculations. The position of the 2⁺ energy levels and behavior of 8⁺ isomers in even-even ^70-76Ni isotopes has been interpreted

No abstract available

[en] The detection system based on Digital Signal Processing has been developed at ORNL and applied to study proton radioactivity. Novel concepts of the Digital Spectroscopy are presented. They have been applied in experiments difficult or impossible to perform with standard systems which combine shaping amplifiers with analog-to-digital converters. The DSP features, such as, trigger-less operation, pulse shape recording and pulse shape based triggering schemes, led to successful measurements of the fine structure in the proton decay of 145Tm and 141Ho and to observation of the two-proton emission in 45Fe

[en] Significant advantages can be obtained through the application of digital electronics to nuclear physics experiments by replacing the traditional timing and shaping circuits by numerical algorithms implemented in real time. One example demonstrating the power of digital techniques is the achievement of a low-energy threshold, <50 keV, for the detection of beta-decay electrons in a thick Si detector. Such a low beta detection threshold would dramatically improve the detection efficiency in standard beta decay correlation experiments.

[en] The decay of extremely neutron-deficient isotope ⁴⁵Fe has been studied by using a new type of gaseous detector in which a technique of optical imaging is used to record tracks of charged particles. The two-proton radioactivity and the beta-decay channels accompanied by proton(s) emission were clearly identified. For the first time, the angular and energy correlations between two protons emitted from the ⁴⁵Fe ground-state were measured. The obtained distributions were confronted with predictions of a three-body model. Studies of beta-decay channels of ⁴⁵Fe provided first unambiguous evidence for the beta-delayed three proton emission

[en] An island of isomers have recently been observed on both sides of the N=40 shell below the Ni isotopes. Isomeric states in the 65Fe and 67Fe allow the knowledge of the single particle structure around the g9/2 shell. Moreover, the excitation energy of the first 2+ and 4+ states in the 68Fe have been established by β-γ correlation. The evolution of the structure of the Fe isotopes going far away from the valley of stability is, for the first time, given for N>40

[en] The discovery of the new isotopes 109Xe and 105Te was enabled by the application of a new experimental method using selective pulse shape storage from silicon detectors with digital signal processing electronics. Essential data processing algorithms were developed, which are able to find unique nuclear decay signatures, such as overlapping alpha decay induced signals. An experiment using this method led to the simultaneous detection of isotopes with dramatically different half lives T1/2(109Xe)=13(2) ms and T1/2(105Te)=620(70) ns. The ground state decay energies have been measured to be E (109Xe)=4062(7) keV and E (105Te)=4703(5) keV via observation of correlated events in the decay chain 109Xe 105Te 101Sn