Search for 2p Decay of the First Excited State of 17 Ne

Structure of nuclei located near and beyond the drip-lines plays important role in the explosive astrophysical processes. The problem of two-proton decay of the 17Ne first excited state is a good example of such situation. The two-proton radiative capture is a possible bypass of the 15O waiting point in the rp-process. The rate of this process drastically depends on the value of the weak

Deep excursion beyond the proton dripline. I. Argon and chlorine isotope chains

The proton-unbound argon and chlorine isotopes have been studied by measuring trajectories of their decay-in-flight products by using a tracking technique with microstrip detectors. The proton (1p) and two-proton (2p) emission processes have been detected in the measured angular correlations "heavy-fragment"+p and "heavy-fragment"+p+p, respectively. The ground states of the previously unknown isotopes Cl30 and Cl28 have been observed for the first time, providing the 1p-separation energies Sp of -0.48(2) and -1.60(8), MeV, respectively. The relevant systematics of 1p- and 2p-separation energies have been studied theoretically in the core+p and core+p+p cluster models. The first-time observed excited states of Ar31 allow one to infer the 2p-separation energy S2p of 6(34) keV for its ground state. The first-time observed state in Ar29 with S2p=-5.50(18) MeV can be identified as either a ground state or an excited state according to different systematics

Three-body correlations data analysis through monte carlo simulation in decay of 10He

This work concerns the program for Monte Carlo (MC) simulation of three-body decays data. Three-body events are characterized by complicated correlations hindered by induced distortions due to finite resolution of experimental setups. The MC code is developed and tested by performing the analysis of the 10He experiment which shows the unusual order of first excited states of 10He

Observation and Spectroscopy of New Proton-Unbound Isotopes Ar-30 and Cl-29: An Interplay of Prompt Two-Proton and Sequential Decay

Previously unknown isotopes Ar-30 and Cl-29 have been identified by measurement of the trajectories of their in-flight decay products S-28 + p + p and S-28 + p, respectively. The analysis of angular correlations of the fragments provided information on decay energies and the structure of the parent states. The ground states of Ar-30 and Cl-29 were found at 2.25(-0.10)(+0.15) and 1.8 +/- 0.1 MeV above the two-and one-proton thresholds, respectively. The lowest states in Ar-30 and Cl-29 point to a violation of isobaric symmetry in the structure of these unbound nuclei. The two-proton decay has been identified in a transition region between simultaneous two-proton and sequential proton emissions from the Ar-30 ground state, which is characterized by an interplay of three-body and two-body decay mechanisms. The first hint of a fine structure of the two-proton decay of Ar-30*(2(+)) has been obtained by detecting two decay branches into the ground and first-excited states of the S-28 fragment

Towards the Limits of Existence of Nuclear Structure: Observation and First Spectroscopy of the Isotope K-31 by Measuring Its Three-Proton Decay

The most remote isotope from the proton dripline (by 4 atomic mass units) has been observed: K-31. It is unbound with respect to three-proton (3p) emission, and its decays have been detected in flight by measuring the trajectories of all decay products using microstrip detectors. The 3p emission processes have been studied by the means of angular correlations of S-28 + 3p and the respective decay vertices. The energies of the previously unknown ground and excited states of K-31 have been determined. This provides its 3p separation energy value S-3p of -4.6(2) MeV. Upper half-life limits of 10 ps of the observed K-31 states have been derived from distributions of the measured decay vertices

Spectroscopy of excited states of unbound nuclei 30^{30}Ar and 29^{29}Cl

Several states of proton-unbound isotopes $^{30}$Ar and $^{29}$Cl were investigated by measuring their in-flight decay products, $^{28}$S+proton+proton and $^{28}$S+proton, respectively. A refined analysis of $^{28}$S-proton angular correlations indicates that the ground state of $^{30}$Ar is located at $2.45^{+0.05}_{-0.10}$ MeV above the two-proton emission threshold. The theoretical investigation of the $^{30}$Ar ground state decay demonstrates that its mechanism has the transition dynamics with a surprisingly strong sensitivity of the correlation patterns of the decay products to the two-proton decay energy of the $^{30}$Ar ground state and the one-proton decay energy as well as the one-proton decay width of the $^{29}$Cl ground state. The comparison of the experimental $^{28}$S-proton angular correlations with those resulting from Monte Carlo simulations of the detector response illustrates that other observed $^{30}$Ar excited states decay by sequential emission of protons via intermediate resonances in $^{29}$Cl. Based on the findings, the decay schemes of the observed states in $^{30}$Ar and $^{29}$Cl were constructed. For calibration purposes and for checking the performance of the experimental setup, decays of the previously-known states of a two-proton emitter $^{19}$Mg were remeasured. Evidences for one new excited state in $^{19}$Mg and two unknown states in $^{18}$Na were found

Deep excursion beyond the proton dripline. II. Toward the limits of existence of nuclear structure

Prospects of experimental studies of argon and chlorine isotopes located far beyond the proton dripline are studied by using systematics and cluster models. The deviations from the widespread systematics observed in $^{28,29}$Cl and $^{29,30}$Ar have been theoretically substantiated, and analogous deviations predicted for the lighter chlorine and argon isotopes. The limits of nuclear structure existence are predicted for Ar and Cl isotopic chains, with $^{26}$Ar and $^{25}$Cl found to be the lightest sufficiently long-living nuclear systems. By simultaneous measurements of protons and $\gamma$-rays following decays of such systems as well as their $\beta$-delayed emission, an interesting synergy effect may be achieved, which is demonstrated by the example of $^{30}$Cl and $^{31}$Ar ground state studies. Such synergy effect may be provided by the new EXPERT setup (EXotic Particle Emission and Radioactivity by Tracking), being operated inside the fragment separator and spectrometer facility at GSI, Darmstadt.Comment: 10 pages, 9 figures. Chapter added, language and some figures correcte