β-decay of 35Ca

1999

Abstract The β-decay of the T z =− 5 2 nucleus 35 Ca was studied at the LISE3 spectrometer at GANIL. The 35 Ca decay scheme was deduced from its β-delayed proton emission into the ground and excited states of 34 Ar and from its β-delayed two-proton emission. The 35 Ca half-life was determined to be 25.7±0.2 ms. The measured transition strength function B(GT) is compared to results obtained from large-scale sd-shell model calculations.

Study of $^{45}$Ar through (d, p) reaction at SPIRAL

2005

NESTER; International audience; The structure of the neutron-rich nucleus $^{45}$Ar has been investigated through the d($^{44}$Ar,$^{45}$Ar)p transfer reaction. Radioactive beam of $^{44}$Ar at 10 A MeV has been provided by the SPIRAL facility at GANIL. The protons corresponding to a neutron pick-up on bound or unbound states mechanism in $^{45}$Ar nuclei were detected at backward angles by the detector array MUST. The transfer-like ejectiles were detected in the SPEG spectrometer. Level scheme, spin assignments and spectroscopic factors have been deduced for $^{45}$Ar and compared to shell model predictions. These parameters will be subsequently used to infer (n, $\gamma$) cross sections i…

PIPERADE: A double Penning trap for mass separation and mass spectrometry at DESIR/SPIRAL2

2021

International audience; A double Penning trap is being commissioned at CENBG Bordeaux for the future DESIR/SPIRAL2 facility of GANIL. The setup is designed to perform both high-resolution mass separation of the ion beam for trap-assisted spectroscopy, and high-accuracy mass spectrometry of short-lived nuclides. In this paper, the technical details of the new device are described. First offline tests with the purification trap are also presented, showing a mass resolving power of about 105.

New neutron-deficient isotopes from $^{78}$Kr fragmentation

2016

In an experiment with the BigRIPS separator at the RIKEN Nishina Center, the fragmentation of a $^{78}$Kr beam allowed the observation of new neutron-deficient isotopes at the proton drip-line. Clean identification spectra could be produced and $^{63}$Se, $^{67}$Kr, and $^{68}$Kr were identified for the first time. In addition, $^{59}$Ge was also observed. Three of these isotopes, $^{59}$Ge, $^{63}$Se, and $^{67}$Kr, are potential candidates for ground-state two-proton radioactivity. In addition, the isotopes $^{58}$Ge, $^{62}$Se, and $^{66}$Kr were also sought but without success. The present experiment also allowed the determination of production cross sections for some of the most exotic…

Observation of the 2+ isomer in Co52

2016

We report the first observation of the ${2}^{+}$ isomer in $^{52}\mathrm{Co}$, produced in the $\ensuremath{\beta}$ decay of the ${0}^{+}$, $^{52}\mathrm{Ni}$ ground state. We have observed three $\ensuremath{\gamma}$ rays at 849, 1910, and 5185 keV characterizing the $\ensuremath{\beta}$ de-excitation of the isomer. We have measured a half-life of 102(6) ms for the isomeric state. The Fermi and Gamow-Teller transition strengths for the $\ensuremath{\beta}$ decay of $^{52m}\mathrm{Co}$ to $^{52}\mathrm{Fe}$ have been determined. We also add new information on the $\ensuremath{\beta}$ decay of the ${6}^{+}$, $^{52}\mathrm{Co}$ ground state, for which we have measured a half-life of 112(3) ms.

Studying the Exotic Decay $^{70}Kr$ $\rightarrow$ $^{70}Br$

2019

Acta physica Polonica / B 51(3), 587 (2020). doi:10.5506/APhysPolB.51.587

Radioactivity of neutron-rich oxygen fluorine and neon isotopes

1999

The $\ensuremath{\gamma}$ radiation and neutrons emitted following the $\ensuremath{\beta}$ decays of ${}^{24}\mathrm{O},$ ${}^{25--27}\mathrm{F},$ and ${}^{28\ensuremath{-}30}\mathrm{Ne}$ have been measured. The nuclides were produced in the quasifragmentation of a 2.8 GeV ${}^{36}\mathrm{S}$ beam, separated in-flight and identified through time-of-flight and energy-loss measurements. The ions were stopped in a silicon detector telescope, which was used to detect the $\ensuremath{\beta}$ particles emitted in their subsequent radioactive decay. The coincident $\ensuremath{\gamma}$ rays were measured using four large volume germanium detectors mounted close to the implantation point and the …

New information on β-delayed neutron emission from Be-12, Be-14

1999

17 pages, 3 tables, 5 figures, 1 appendix.-- PACS nrs.: 23.40.Hc; 27.20.+n.

Super-Allowed β Decay of23Mg Studied with a High-Precision Germanium Detector

2015

Crossing the dripline to11Nusing elastic resonance scattering

2000

The level structure of the unbound nucleus N-11 has been studied by C-10+p elastic resonance scattering in inverse geometry with the LISE3 spectrometer at GANIL, using a C-10 beam with an energy of 9.0 MeV/ nucleon. An additional measurement was done at the A1200 spectrometer at MSU. The excitation function above the C-10+p threshold has been determined up to 5 MeV. A potential-model analysis revealed three resonance states at energies 1.27(-0.05)(+0.18) MeV (Gamma = 1.44 +/- 0.2 MeV), 2.01(-0.05)(+0.15) MeV (Gamma = 0.84 +/- 0.2 MeV), and 3.75 +/- 0.05 MeV (Gamma = 0.60 +/- 0.05 MeV) with the spin-parity assignments I-pi=1/2+,1/2,-,5/2+, respectively. Hence, N-11 is shown to have a ground …

Neutron-rich isotopesTi54−57

1996

The neutron-rich isotopes $^{54\mathrm{\ensuremath{-}}57}\mathrm{Ti}$ and $^{58\mathrm{\ensuremath{-}}60}\mathrm{Cr}$ are produced by fragmentation of a 64.5 MeV/nucleon $^{65}\mathrm{Cu}^{26+}$ beam in a 90 mg/${\mathrm{cm}}^{2}$ $^{9}\mathrm{Be}$ target. Following particle identification by energy loss and time of flight, the radioactive decay was observed by \ensuremath{\beta} singles and \ensuremath{\beta}\ensuremath{\gamma}-coincidence measurements. The results obtained for $^{58\mathrm{\ensuremath{-}}60}\mathrm{Cr}$ are compared to previous results, whereas the decay of the $^{54\mathrm{\ensuremath{-}}57}\mathrm{Ti}$ isotopes is studied here. \ensuremath{\gamma}-ray intensities and en…

Nuclear weak response from the combined study of beta-decay and charge-exchange reaction

2009

Studying the weak nuclear response, especially the Gamow-Teller (GT) transitions, of stable as well as unstable pf-shell nuclei, is one of the key issues in nuclear and astro-nuclear physics. We study the decay half-lives and the GT transitions starting from Tz = ±1 and ±2 mirror nuclei, respectively, by means of β decays and complementary hadronic (3 He , t) charge-exchange reactions. Under the assumption that isospin is a good quantum number, symmetry is expected for mirror nuclei and the GT transitions starting from the mirror nuclei. The half-lives and branching ratios and the measured strength distributions of GT transitions are compared and also combined for the understanding of the …

Light exotic isotopes: recent beam developments and physics applications at ISOLDE

2002

This paper is divided in three parts: (i) the measurement of yields and decay losses of Li and Be isotopes released from a thin foil tantalum target at the CERN/ISOLDE PS-Booster; (ii) results from beta-decay experiments on Be-12 and Be-14, an improved half-life of 21.49(3) ms has been obtained for Be-12; (iii) the beta-decay of C-9. An outline of the analysis procedure to determine the branching at high excitation energies is given. The ground-state branch has been determined to 54.1(15)%.

New region of deformation in the neutron-rich 60 24Cr36 and 62 24Cr38

2003

The neutron-rich nuclei 23 60-63V have been produced at GANIL via interactions of a 61.8A·MeV 76Ge beam with a 58Ni target. Beta-decay to 24 60-63Cr has been investigated using combined β- and γ-ray spectroscopy. Half-lives of the 60-63V nuclei have been determined, and the existence of a beta-decay isomer in the 60V nucleus is strongly supported. The observation of low-energy 2+ states in 60Cr (646keV) and 62Cr (446keV) suggests that these isotopes are strongly deformed with β2 ∼ 0.3. This is confirmed by shell model calculations which show the dominant influence of the intruder g and d orbitals to obtain low 2+ energies in the neutron-rich Cr isotopes.

Beta decay of the exotic Tz = - 2, $^{56}$Zn nucleus and half-life of various proton-rich Tz = -1 nuclei

2014

Expérience GANIL/LISE3/EXOGAM; International audience; Preliminary results of an experimental study of the beta -decay of the exotic T$_z$ = - 2, $^{56}$Zn nucleus and other proton-rich T$_z$ = -1 nuclei are presented. The ions were produced at GANIL using fragmentation reactions, separated by the LISE3 spectrometer and implanted in a double-sided silicon strip detector surrounded by Ge detectors. The half-lives of $^{56}$Zn and four T$_z$ = -1 nuclei in the fp-shell have been measured. While the decay of the T$_z$ = -1 nuclei proceeds essentially by -delayed gamma emission, in the case of $^{56}$Zn -delayed proton emission is also observed. Moreover, the exotic -delayed gamma-proton decay …

First beta-decay studies of the neutron-rich isotopes 53-55Sc and 56-59V

1998

The neutron-rich isotopes Sc53-55 and V56-59 have been produced at GANIL in interactions of a 64.5 MeV/u Cu-65 beam with a Be-9 target. They were separated by the doubly achromatic spectrometer LISE3. Beta-decay half-lives and subsequent low-energy gamma-rays were observed for the first time. The present results are compared to QRPA model predictions. The quick drop of the half-life observed at N = 33 for Ca-53(20)33 is water V-56(23)33 and absent for Sc-54(21)33, indicating a vanishing of the N = 32 subshell north to Ca-52(32). In an astrophysical context, these neutron-rich isotopes represent r-process progenitors which, after beta-decay, would produce the correlated isotopic over-abundan…

Structure of theN=27isotones derived from theAr44(d,p)Ar45reaction

2008

The $^{44}\mathrm{Ar}$($d,p$)$^{45}\mathrm{Ar}$ neutron transfer reaction was performed at $10A$ MeV. Measured excitation energies, deduced angular momenta, and spectroscopic factors of the states populated in $^{45}\mathrm{Ar}$ are reported. A satisfactory description of these properties is achieved in the shell model framework using a new $\mathit{sdpf}$ interaction. The model analysis is extended to more exotic even-$Z$ nuclei down to ${}_{14}^{41}{\mathrm{Si}}_{27}$ to study how collectivity impacts the low-lying structure of $N=27$ neutron-rich nuclei.

Two-Proton Radioactivity ofKr67

2016

In an experiment with the BigRIPS separator at the RIKEN Nishina Center, we observed two-proton (2p) emission from 67Kr. At the same time, no evidence for 2p emission of 59Ge and 63Se, two other potential candidates for this exotic radioactivity, could be observed. This observation is in line with Q value predictions which pointed to 67Kr as being the best new candidate among the three for two-proton radioactivity. 67Kr is only the fourth 2p ground-state emitter to be observed with a half-life of the order of a few milliseconds. The decay energy was determined to be 1690(17) keV, the 2p emission branching ratio is 37(14)%, and the half-life of 67Kr is 7.4(30) ms.

Beta-decay of light nuclei close to the proton drip-line: 40Ti and 35Ca

1998

The s-decay of40Ti and35Ca have been studied at the LISE3 spectrometer at GANIL. The decay schemes were deduced from the observed s-delayed proton and γ emission of40Ti and35Ca into the ground and first excited states of39Ca and34Ar, respectively. The Gamow-Teller strength functionB(GT) of the40Ti s-decay extracted from the s-decay branching ratios and the precisely measured40Ti half-life, provides for the first time an experimental calibration of the neutrino detection efficiency for the ICARUS solar neutrino detector.

β decay of the very neutron-deficient Ge60 and Ge62 nuclei

2021

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…

Beta-decay half-lives at the N = 28 shell closure

2004

Abstract Measurements of the beta-decay half-lives of neutron-rich nuclei (MgAr) in the vicinity of the N =28 shell closure are reported. Some 22 half-lives have been determined, 12 of which for the first time. Particular emphasis is placed on the results for the Si isotopes, the half-lives of which have been extended from N =25 to 28. Comparison with QRPA calculations suggests that 42 Si is strongly deformed. This is discussed in the light of a possible weakening of the spin–orbit potential.

New transitions in the $\beta$-decay of $^{36}$Ca

2001

The β-decay of the Tz = - 2 nucleus 36Ca was studied at the LISE3 magnetic spectrometer at GANIL. Two new proton-emitting states have been detected and the other nine known βp and βγ transitions have been remeasured with improved resolution. A simulation with the GEANT code has been applied to this experimental setup. A comparison with shell model calculations is given.

Beta decay studies of neutron-rich $_{21}$Sc-$_{27}$Co nuclei at GANIL

2002

Abstract The neutron-rich nuclei 2157,58Sc, 2258–60Ti, 2258–60Ti, 2360–62V, 2464–66Cr, 2564–68Mn, 2667–70Fe and 2769–71Co have been produced at Ganil via interactions of a 61.8 A.MeV 76Ge beam with a 58Ni target. Beta-decay studies have been achieved, bringing new half-lives and a better nuclear structure knowledge in this region. These results could help for understanding the overabundances of the neutron-rich stable 58Fe, 64Ni in certain inclusions of meteorites.

Odd-odd neutron-rich rhodium isotopes studied with the double Penning trap JYFLTRAP

2022

Precision mass measurements of neutron-rich rhodium isotopes have been performed at the JYFLTRAP Penning trap mass spectrometer at the Ion Guide Isotope Separator On-Line (IGISOL) facility. We report results on ground- and isomeric-state masses in $^{110,112,114,116,118}$Rh and the very first mass measurement of $^{120}$Rh. The isomeric states were separated and measured for the first time using the phase-imaging ion-cyclotron-resonance (PI-ICR) technique. For $^{112}$Rh, we also report new half-lives for both the ground state and the isomer. The results are compared to theoretical predictions using the BSkG1 mass model and discussed in terms of triaxial deformation.

$\beta $-delayed $\gamma $-proton Decay in $^{56}$Zn: Analysis of the Charged-particle Spectrum

2014

A study of the $\beta$ decay of the proton-rich $T_{z}$ = -2 nucleus $^{56}$Zn has been reported in a recent publication. A rare and exotic decay mode, $\beta$-delayed $\gamma$-proton decay, has been observed there for the first time in the $fp$ shell. Here we expand on some of the details of the data analysis, focussing on the charged particle spectrum.

Simultaneous investigation of the T=1(Jπ=0+) and T=0(Jπ=9+) β decays in Br70

2017

The $\beta$ decay of the odd-odd nucleus $^{70}$Br has been investigated with the BigRIPS and EURICA setups at the Radioactive Ion Beam Factory (RIBF) of the RIKEN Nishina Center. The $T=0$ ($J^{\pi}=9^+$) and $T=1$ ($J^{\pi}=0^+$) isomers have both been produced in in-flight fragmentation of $^{78}$Kr with ratios of 41.6(8)\% and 58.4(8)\%, respectively. A half-life of $t_{1/2}=2157^{+53}_{-49}$ ms has been measured for the $J^{\pi}=9^+$ isomer from $\gamma$-ray time decay analysis. Based on this result, we provide a new value of the half-life for the $J^{\pi}=0^+$ ground state of $^{70}$Br, $t_{1/2}=78.42\pm0.51$ ms, which is slightly more precise, and in excellent agreement, with the bes…

Observation of theβ-Delayedγ-Proton Decay ofZn56and its Impact on the Gamow-Teller Strength Evaluation

2014

We report the observation of a very exotic decay mode at the proton drip line, the $\ensuremath{\beta}$-delayed $\ensuremath{\gamma}$-proton decay, clearly seen in the $\ensuremath{\beta}$ decay of the ${T}_{z}=\ensuremath{-}2$ nucleus $^{56}\mathrm{Zn}$. Three $\ensuremath{\gamma}$-proton sequences have been observed after the $\ensuremath{\beta}$ decay. Here this decay mode, already observed in the $sd$ shell, is seen for the first time in the $fp$ shell. Both $\ensuremath{\gamma}$ and proton decays have been taken into account in the estimation of the Fermi and Gamow-Teller strengths. Evidence for fragmentation of the Fermi strength due to strong isospin mixing is found.

Precise measurements of half-lives and branching ratios for the ββ mirror transitions in the decay of 23Mg and 27Si

2017

Half-lives and branching ratios for the two mirror ββ decays of 23Mg and 27Si have been measured at the University of Jyväskylä with the IGISOL facility. The results obtained, T1/2=11.303(3)T1/2=11.303(3) s and T1/2=4.112(2)T1/2=4.112(2) s for the half-lives of 23Mg and 27Si , respectively, are 7 and 8 times more precise than the averages of previous measurements. The values obtained for the super-allowed branching ratios of 23Mg and 27Si are B.R.=92.18(8)%B.R.=92.18(8)% and B.R.=99.74(2)%B.R.=99.74(2)% , respectively. The result for 23Mg is three times more precise than the average of the previous measurements, while for 27Si the precision has not been improved, the average of the previous…