Extraction of energy and time from pile-up pulses with fast sampling ADC analysis techniques

Abstract: Debates of whether Z=114 and N=184 are the next magic numbers in nuclear physics have existed since the earliest predictions made in the 1960s. Until these days they have not been firmly established. To get a better understanding of the magic numbers, it is of key importance to study the nuclei in the vicinity of established and anticipated shell closures. Above shell closures, fast alpha-decaying nuclei with half-lives down to tens of nano seconds exist. Due to their short lifetimes, it has been difficult to measure their properties as $\alpha$-decays result in pile-ups with an analogue electronics experimental set-up. Fast sampling ADCs have recently been employed in nuclear physics experiments and they have made it possible to extract energies and times of pile-ups with tailor-made algorithms. For the superheavy element 115 experiment, conducted in 2012 by the Lund University Nuclear Structure Group, the employment of fast sampling ADCs was the case. Besides element 115 (E115) decay chains, many short-lived alpha-decaying transfer reaction products were detected. In this work, the digital pulse processing and in particluar the moving window deconvolution algorithm, which is used to determine amplitudes from digitised preamplifier signals, are employed to study those short-lived alpha-decaying nuclei. A unique pile-up trace analysis routine is developed to extract the energies and times from the preamplifier traces and is applied to the experimental data. From the obtained results a connection to the tabulated alpha-decay chain of Ra-219 to Rn-215 could be firmly established. The alpha-decay energy values and coincident gamma rays agreed with the tabulated data while the obtained half-life was improved. A decay level scheme could be created on the basis of this work. With the established decay path, this thesis establishes the proof-of-concept of energy and time extractions with a digital pulse processing system with an algorithm routine to study the properties of very short-lived alpha-decaying nuclei. There is a lot of data left to be analysed and potentially new decay paths can be discovered or improve assessed branching ratios.