Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userBeta decay of the very neutron-deficient $^{60}$Ge and $^{62}$Ge nuclei
87
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We report here the results of a study of the $beta$ decay of the proton-rich Ge isotopes, $^{60}$Ge and $^{62}$Ge, produced in an experiment at the RIKEN Nishina Center. We have improved our knowledge of the half-lives of $^{62}$Ge (73.5(1) ms), $^{60}$Ge (25.0(3) ms) and its daughter nucleus, $^{60}$Ga (69.4(2) ms). We measured individual $beta$-delayed proton and $gamma$ emissions and their related branching ratios. Decay schemes and absolute Fermi and Gamow-Teller transition strengths have been determined. The mass excesses of the nuclei under study have been deduced. A total $beta$-delayed proton-emission branching ratio of 67(3)% has been obtained for $^{60}$Ge. New information has been obtained on the energy levels populated in $^{60}$Ga and on the 1/2$^-$ excited state in the $beta p$ daughter $^{59}$Zn. We extracted a ground state to ground state feeding of 85.3(3)% for the decay of $^{62}$Ge. Eight new $gamma$ lines have been added to the de-excitation of levels populated in the $^{62}$Ga daughter.
rate research
Read More
The Majorana Experiment is a next-generation Ge-76 double-beta decay search. It will employ 500 kg of Ge, isotopically enriched to 86% in Ge-76, in the form of 200 detectors in a close-packed array for high granularity. Each crystal will be electronically segmented, with each region fitted with pulse-shape analysis electronics. A half-life sensitivity is predicted of 4.2e27 y or <m_nu> < 0.02-0.07 eV, depending on the nuclear matrix elements used to interpret the data.
Background: The observation of the superdeformed (SD) bands in $^{60,62}$Zn indicates a strong SD-shell effect at the particle numbers 30 and 32, where two and four neutron single-particles are considered to be promoted to the intruder $1g_{9/2}$ shell. However, the SD-yrast band in $^{62}$Zn is assigned negative parity. Purpose: I investigate various SD configurations in the rapidly rotating $^{60,62}$Zn isotopes, and attempt elucidating the different roles of the SD magic numbers 30 and 32. Method: I employ a nuclear energy-density functional (EDF) method: the configuration-constrained cranked Skyrme-Kohn-Sham approach is used to describe the rotational bands near the yrast line. Results: I find that the neutron number 32 favors stronger deformation than 30; a competing shell effect of protons and neutrons makes the SD-yrast structures of $^{62}$Zn unique. Due to the coherent shell effect, the positive-parity band emerges in $^{64}$Ge as an SD-yrast band with greater deformation than that in $^{60,62}$Zn. Furthermore, the present calculation predicts the occurrence of the hyperdeformed (HD) magic numbers 30 and 32 at a high rotational frequency $sim 2.0$ MeV$/hbar$. Conclusions: The negative-parity SD bands appear higher in energy than the positive-parity SD-yrast band in $^{60}$Zn and $^{64}$Ge, indicating that both the particle numbers 30 and 32 are SD magic numbers. The positive-parity HD states appear as the yrast band at $I sim 50hbar$ in $^{60}$Zn and $^{64}$Ge. The particle numbers 30 and 32 are magic numbers of SD and HD.
Masses of the radioactive isotopes 62Ga, 62Zn and 62Cu have been measured at the JYFLTRAP facility with a relative precision of better than 18 ppb. A Q_EC value of (9181.07 +- 0.54) keV for the superallowed decay of 62Ga is obtained from the measured cyclotron frequency ratios of 62Ga-62Zn, 62Ga-62Ni and 62Zn-62Ni ions. The resulting Ft-value supports the validity of the conserved vector current hypothesis (CVC). The mass excess values measured were (-51986.5 +-1.0) keV for 62Ga, (-61167.9 +- 0.9) keV for 62Zn and (-62787.2 +- 0.9) keV for 62Cu.
The GERDA experiment searches for the lepton number violating neutrinoless double beta decay of $^{76}$Ge ($^{76}$Ge $rightarrow$ $^{76}$Se + 2e$^-$) operating bare Ge diodes with an enriched $^{76}$Ge fraction in liquid argon. The exposure for BEGe-type detectors is increased threefold with respect to our previous data release. The BEGe detectors feature an excellent background suppression from the analysis of the time profile of the detector signals. In the analysis window a background level of $1.0_{-0.4}^{+0.6}cdot10^{-3}$ cts/(keV$cdot$kg$cdot$yr) has been achieved; if normalized to the energy resolution this is the lowest ever achieved in any 0$ ubetabeta$ experiment. No signal is observed and a new 90 % C.L. lower limit for the half-life of $8.0cdot10^{25}$ yr is placed when combining with our previous data. The median expected sensitivity assuming no signal is $5.8cdot10^{25}$ yr.
The $beta$-decay and isomeric properties of $^{54}$Sc, $^{50}$K and $^{53}$Ca are presented, and their implications with respect to the goodness of the N=32 sub-shell closure discussed.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
